bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmammary Infection of Newborn by Larval Trematodes
Authors: Shoop Wesley L. , Corkum Kenneth C.
Published: October 2006

Newborn cats and mice became infected with
Alaria marcianae
if they nursed from females that had been experimentally infected with the parasite. All lactating females showed mesocercarial stages in their mammary glands. This may be the first trematode found to undergo transmission through the mammary glands under experimental conditions. Similarities in the behavior of mesocercariae in humans and in the mouse suggest that an infected human female might infect her infant if she elected to nurse it.
Estrogen Receptor Analysis by Flow Cytometry
Authors: Van Nguyen T. , Raber Martin , Barrows George H. , Barlogie Bart
Published: October 2006

A fluorescently labeled estradiol, N′-fluoresceino-N′-(17β-estradiol hemisuccinamide) thiourea (FE) was used for measuring estrogen receptor content per cell in tumor cells. The cellular content of FE was measured quantitatively by flow cytometry. Binding of FE occurs in the nanomolar concentration range, an indication of the high affinity of the labeled estradiol. Competition of FE for binding sites is observed with estrogens, but not with progestins, androgens, or glucocorticosteroids, indicating the specificity of FE binding. In contrast to other estrogen receptor assays, this new technique requires a small sample size (about 5000 cells) and permits the assessment of heterogeneity in estrogen receptor expression among tumor cells.
Perinatal Dopamine-Related Drugs Demasculinize Rats
Authors: Hull Elaine M. , Nishita J. Ken , Bitran Daniel , Dalterio Susan
Published: October 2006

Administration of haloperidol, a common neuroleptic, to pregnant or lactating rats impaired the masculine sex behavior of their male offspring. Prenatal haloperidol did not affect testosterone concentrations in fetuses. Maternal administration of apomorphine, a dopamine agonist, and of α-methyl-
p
-tyrosine, an inhibitor of dopamine synthesis, also demasculinized male offspring. In both experiments other behaviors and developmental milestones were unaffected. Perinatal haloperidol, apomorphine, and α-methyl-
p
-tyrosine did not lower testosterone in adulthood. These drugs may act directly on neurons that control masculine behavior without lowering testosterone prenatally or in adulthood.
Sex Pheromone of the Tsetse Fly: Isolation, Identification, and Synthesis of Contact Aphrodisiacs
Authors: Carlson D. A. , Langley P. A. , Huyton P.
Published: October 2006

Sex pheromones isolated from the cuticle of the female tsetse fly,
Glossina morsitans morsitans
Westwood, release mating behavior in the male fly at ultrashort range or upon contact with baited decoys. Three active components were identified as 15,19-dimethylheptatriacontane, 17,21-dimethylheptatriacontane, and 15,19,23-trimethylheptatriacontane. Chemical and biological comparisons show that the natural and synthetic compounds are identical.
Experimental Allergic Encephalomyelitis in Lewis Rats: Chemical Synthesis of Disease-Inducing Determinant
Authors: Hashim G. A.
Published: October 2006

Two amino acid sequences from the same regions of guinea pig and bovine myelin basic protein which induce experimental allergic encephalomyelitis in Lewis rats were synthesized. The sequences of these two regions may be defined by residues 69 to 84 of the bovine basic protein. The encephalitogenic sequence from guinea pig basic protein (peptide S49), H-Gly-Ser-Leu-Pro-Gln-Lys-Ala-Gin-Arg-Pro-Gln-Asp-Glu-Asn-OH, is a much more potent encephalitogen than that of H-Gly-Ser-Leu-Pro-Gln-Lys-Ala-Gln-Gly-His-Arg-Pro-Gln-Asp-Glu-Asn-OH (peptide S8) found in the bovine protein. The primary structures of the two determinants are similar; however, a Gly-His deletion from the guinea pig sequence is noted. Study of the encephalitogenicity of peptide S49, peptide S8, and the parent proteins suggests that the difference in the encephalitogenic potency of the parent proteins in Lewis rats is due to a natural modification in the primary structure of their respective encephalitogenic determinants.
Single-Nutrient Microbial Competition: Qualitative Agreement Between Experimental and Theoretically Forecast Outcomes
Authors: Hansen Stephen R. , Hubbell Stephen P.
Published: October 2006

When microbial strains compete for the same limiting nutrient in continuous culture, resource-based competition theory predicts that only one strain will survive and all others will die out. The surviving strain expected from theory will be the one with the smallest subsistence or "break-even" concentration of the limiting resource, a concentration defined by the
J
parameter. This prediction has been confirmed in the case of auxotrophic bacterial strains competing for limiting tryptophan. Because the value of
J
can be measured on the strains grown alone, the theory can predict the qualitative outcomes of mixed-growth competition in advance of actual competition.
Male Contraception; Synergism of Gonadotropin-Releasing Hormone Analog and Testosterone in Suppressing Gonadotropin
Authors: Heber D. , Swerdloff R. S.
Published: October 2006

Long-term administration of either superactive analog's of gonadotropin-releasing hormone or of testosterone suppresses gonadotropin secretion in male animals and humans. Testosterone administered in combination with gonadotropin-releasing hormone analog further suppresses serum gonadotropin levels in male rats. This observation indicates synergistic activity and suggests that the gonadotropin-releasing hormone analog and testosterone act at independent sites within the hypothalamic-pituitary axis. The primary actions of superactive analog are probably mediated by changes at a postreceptor site in the pituitary gonadotropin-secreting cells.
Primate Memory: Retention of Serial List Items by a Rhesus Monkey
Authors: Sands Stephen F. , Wright Anthony A.
Published: October 2006

A rhesus monkey correctly recognized 86 and 81 percent of 10- and 20-item lists, respectively. Its serial position curve was similar in form to a human's curve, revealing prominent primacy and recency effects. The key to these findings was in minimizing proactive interference through the use of a large pool of 211 color photographs.
Mapping of Heavy Chain Genes for Mouse Immunoglobulins M and D
Authors: Liu Chih-Ping , Tucker Philip W. , Mushinski J. Frederic , Blattner Frederick R.
Published: October 2006

A single DNA fragment containing both μ and δ immunoglobulin heavy chain genes has been cloned from normal BALB/c mouse liver DNA with a new λ phage vector Charon 28. The physical distance between the membrane terminal exon of μ and the first domain of δ is 2466 base pairs, with δ on the 3′ side of μ. A single transcript could contain a variable region and both μ and δ constant regions. The dual expression of immunoglobulins M and D on spleen B cells may be due to alternate splicing of this transcript.
Rapid Forgetting of a Spatial Habit in Rats with Hippocampal Lesions
Authors: Thompson Robert
Published: October 2006

Rats with lesions of the hippocampus or mammillary bodies were impaired in learning reversal problems in a T-maze. Test trials given after learning each reversal disclosed little forgetting in the mammillary body group but rapid forgetting in the hippocampal group. These findings resemble those recently reported in patients with amnestic syndromes.
A 7-Hydroxymethyl Sulfate Ester as an Active Metabolite of 7,12-Dimethylbenz[
a
]anthracene
Authors: Watabe Tadashi , Ishizuka Tsuneo , Isobe Masakazu , Ozawa Naoki
Published: October 2006

7-Hydroxymethyl-12-methylbenz[
a
]anthracene (7-HMBA), a carcinogenic major metabolite of 7,12-dimethylbenz[
a
]anthracene (DMBA) in liver, was transformed by liver cytosolic sulfotransferase to reactive 7-HMBA sulfate, which is mutagenic toward
Salmonella typhimurium
strain TA98. The mutagenicity of 7-HMBA in the presence of hepatic sulfotransferase was much higher than that of DMBA or 7-HMBA in the presence of hepatic monooxygenase.
Myoglobin Diffusion in Bovine Heart Muscle
Authors: Livingston David J. , La Mar Gerd N. , Brown W. Duane
Published: October 2006

The rotational mobility of myoglobin in situ was determined by proton nuclear magnetic resonance line width measurements of a characteristic myoglobin resonance observed in bovine heart muscle spectra. The protein diffuses intracellularly at nearly half the rate observed in dilute solution. This high mobility allows the oxygenated form of myoglobin to contribute significantly to the overall diffusive flux of oxygen in respiring heart muscle.
Plasticity of Motor Behavior in Monkeys with Crossed Forelimb Nerves
Authors: Brinkman Cobie , Porter R. , Norman Julie
Published: October 2006

Monkeys in which nerves innervating the flexor muscles of the forearm and hand (the ulnar or the median nerve) had been surgically cross-united with the nerve innervating the extensor muscles (the radial nerve), and vice versa, showed excellent (ulnar-radial crosses) to moderate (median-radial crosses) control of movement performance after regeneration. Antagonistic movement responses were seen occasionally, but these were corrected almost immediately. Stimulation of the crossed nerves showed that they had innervated the antagonistic muscle groups. The results reveal the capacity of the primate central nervous system to adapt to gross disturbances imposed on the execution of movements by changes in peripheral innervation.
Brief Deprivation of Vision After Unilateral Lesions of the Frontal Eye Field Prevents Contralateral Inattention
Authors: Crowne Douglas P. , Richardson Claudette M. , Ward Glenn
Published: October 2006

Brief deprivation of vision after unilateral lesions of the frontal eye field prevents the appearance of contralateral inattention to visual, auditory, and somatosensory stimuli. The forced circling that accompanies inattention, however, is not affected. An equivalent preoperative period in the dark only partly reduces inattention symptoms. Visual deprivation does not reduce or prevent inattention resulting from lesions of the superior colliculus.
Single Visual Neurons Code Opposing Motion Independent of Direction
Authors: Frost B. J. , Nakayama K.
Published: October 2006

Cells in intermediate and deeper layers of the pigeon optic tectum respond best when a textured background pattern is moved in the opposite direction to a moving test spot. Complete inhibition occurs when the background moves in the same direction as the test stimulus. Most noteworthy is the invariance of this relationship over a wide range of test spot directions. These cells represent a higher level of abstraction in a motion-detecting system and may play a role in figure-ground segregation or the discrimination of the motion of an object from self-induced optical motion.
Human Platelet-Derived Growth Factor (PDGF): Amino-Terminal Amino Acid Sequence
Authors: Antoniades Harry N. , Hunkapiller Michael W.
Published: October 2006

Human platelet-derived growth factor (PDGF) obtained from outdated human platelets was subjected to amino-terminal amino acid sequence analysis by automated Edman degradation. Despite the apparent presence of limited proteolytic degradation of the protein derived from this method, the sequence analysis reveals two primary peptide sequences and suggests that active PDGF is composed of two, possibly homologous, peptides linked by a disulfide bond or bonds.
Quaternary and Quinternary Structures of Native Chromatin DNA in Liver Nuclei: Differential Scanning Calorimetry
Authors: Nicolini C. , Trefiletti V. , Cavazza B. , Cuniberti C. , Patrone E. , Carlo P. , Brambilla G.
Published: October 2006

Differential scanning calorimetry of chromatin isolated from rat liver cells revealed three discrete thermal transitions whose temperatures and melting enthalpies depend on ionic strength in the range 0 to 600 millimolar NaCl. Intact nuclei showed a fourth thermal transition at a lower temperature and different melting enthalpies for the other three transitions still present at temperatures similar to those obtained in isolated chromatin. The data are discussed in terms of the tertiary, quaternary, and quinternary structures of chromatin DNA.
Membrane Isolation Alters the Gel to Liquid Crystal Transition of
Acholeplasma laidlawii
B
Authors: Cameron David G. , Martin Adèle , Mantsch Henry H.
Published: October 2006

The gel to liquid crystal phase transition of membrane lipids of live
Acholeplasma laidlawii B
was monitored by infrared spectroscopy. It was found that, while isolated membranes are predominantly in the gel phase at the growth temperature, the live cell membranes contain a large liquid crystal phase component.
Insulin Receptor: Evidence That It Is a Protein Kinase
Authors: Roth Richard A. , Cassell Delanie J.
Published: October 2006

Highly purified preparations of insulin receptor catalyzed the phosphorylation of the 95,000-dalton subunit of the insulin receptor. This subunit of the insulin receptor was also labeled with [α-
32
P]8-azidoadenosine 5′-triphosphate, a photoaffinity label for adenosine triphosphate binding sites. The identity of the 95,000-dalton band was confirmed in both cases by precipitation with a monoclonal antibody to the insulin receptor. These results suggest that the insulin receptor is itself a protein kinase.
Nigral Transplants Reinnervating the Dopamine-Depleted Neostriatum Can Sustain Intracranial Self-Stimulation
Authors: Fray Paul J. , Dunnett Stephen B. , Iversen Susan D. , Björklund Anders , Stenevi Ulf
Published: October 2006

Transplants of embryonic substantia nigra reinnervated the striatum and were able to sustain intracranial self-stimulation in rats with brain lesions induced by 6-hydroxydopamine. Dopaminergic drugs and alterations in current intensity produced typical changes in response rates. Animals with electrodes implanted into cortical grafts or into the denervated striatum failed to exhibit self-stimulation. These findings suggest that transplanted dopamine neurons convey specific, temporally organized information axonally to the striatum.
In Vivo One-Dimensional Imaging of Phosphorus Metabolites by Phosphorus-31 Nuclear Magnetic Resonance
Authors: Haselgrove J. C. , Subramanian V. Harihara , Leigh J. S. , Gyulai L. , Chance B.
Published: October 2006

A phosphorus-31 nuclear magnetic resonance imaging technique has been used to obtain information on phosphorus metabolites from different spatial regions of tissues in vivo. The technique for selection of planes through the tissue is based on phase-encoding of spin echoes and was used to obtain one-dimensional discrimination of phosphorus-31 spectra from different parts of the tissue simultaneously. Specimens were resolved into 16 distinct slices and a signal-to-noise ratio of about 20 to 1 was obtained in ½ hour. Results are presented for phantoms, rat legs, and gerbil heads.
Somatic Mutations of Immunoglobulin Variable Genes Are Restricted to the Rearranged V Gene
Authors: Gorski Jack , Rollini Pierre , Mach Bernard
Published: October 2006

An important question concerning the mechanism of somatic mutation of immunoglobulin variable (V) genes is whether it involves all of the numerous V genes in a differentiated B cell, independent of location, or if it is restricted to a particular chromosomal site. Comparison of the sequence of two alleles of a given V gene shows that the mutations are limited to the rearranged V gene, while the same V gene on the other chromosome has not undergone mutation. This indicates that a V gene sequence alone is not sufficient for somatic mutation to take place. The mutation is therefore restricted to the rearranged V gene and consequently does not occur before rearrangement.
Pulsing Electromagnetic Fields Induce Cellular Transcription
Authors: Goodman Reba , Bassett C. Andrew L. , Henderson Ann S.
Published: October 2006

Weak, pulsing electromagnetic fields can modify biological processes. The hypothesis that responses to such induced currents depend on pulse characteristics was evaluated by using transcription as the target process. Two pulses in clinical use, the repetitive single pulse and the repetitive pulse train, were tested. These pulses produced different results from each other and from controls when transcription in dipteran salivary gland cells was monitored with tritiated uridine in transcription autoradiography, cytological nick translation, and analysis of isolated RNA fractions. The single pulse increased the specific activity of messenger RNA after 15 and 45 minutes of exposure. The pulse train increased specific activity only after 45 minutes of exposure.
Inhibitory Conductance Changes at Synapses in the Lamprey Brainstem
Authors: Gold Michael R. , Martin A. R.
Published: October 2006

Although the conductance and kinetic behavior of inhibitory synaptic channels have been studied in a number of nerve and muscle cells, there has been little if any detailed study of such channels at synapses in the vertebrate central nervous system or of the relation of such channels to natural synaptic events. In the experiments reported here, current noise measurements were used to obtain such information at synapses on Muller cells in the lamprey brainstem. Application of glycine to the cells activated synaptic channels with large conductances and relaxation time constants (70 picosiemens and 33 milliseconds, respectively, at 3° to 10°C). Spontaneous inhibitory synaptic currents had a mean conductance of 107 nanosiemens and decayed with the same time constant. In addition, the glycine responses and the spontaneous currents had the same reversal potential and both were abolished by strychnine. These results support the idea that glycine is the natural inhibitory transmitter at these synapses and suggest that one quantum of transmitter activates about 1500 elementary conductance channels.
Nuclear Magnetic Resonance Blood Flow Measurements in the Human Brain
Authors: Singer J. R. , Crooks L, E.
Published: October 2006

Timed sequences of nuclear magnetic resonance imaging signals in the human head were used to quantitatively measure blood flow in the internal jugular veins. The procedure can be straightforwardly applied to any vein or artery in the body.
Ventral Posterior Thalamic Neurons Differentially Responsive to Noxious Stimulation of the Awake Monkey
Authors: Casey Kenneth L. , Morrow Thomas J.
Published: October 2006

Of 76 cutaneously activated neurons recorded from the ventral posterior thalamus of awake, behaving monkeys, nine were weakly excited by innocuous skin stimulation and responded maximally only when noxious mechanical cutaneous stimuli were delivered within small, contralateral receptive fields. These results show that neurons capable of encoding the spatial and temporal features of noxious stimuli are located in the ventral posterior thalamus of the awake primate.
Human Fetal Muscle and Cultured Myotubes Derived from It Contain a Fetal-Specific Myosin Light Chain
Authors: Strohman R. C. , Micou-Eastwood J. , Glass C. A. , Matsuda R.
Published: October 2006

Human fetal muscles at ages 110, 125, and 132 days contain a fetal-specific myosin light chain. This light chain is absent in adult human muscle, copurifies with myosin, and is identified as a slow light chain because it reacts with purified antibody to chicken slow muscle light chains and does not react strongly with antibody to fast myosin light chains. This light chain is synthesized in cultures of fetal muscle along with normal myosin light chains. The presence of a fetal light chain in culture provides a marker for studies of human muscle disease in which it is important to know when or if the muscle makes a transition from embryonic or fetal expression to true adult phenotype.
Somatomedin B: Mitogenic Activity Derived from Contaminant Epidermal Growth Factor
Authors: Heldin Carl-Henrik , Wasteson Åke , Fryklund Linda , Westermark Bengt
Published: October 2006

The mitogenic effect of somatomedin B on human cultured glial cells was neutralized by the addition of antibodies to mouse epidermal growth factor. Somatomedin B contained epidermal growth factor-like activity, competing for binding to the epidermal growth factor receptor. It is concluded that contaminating epidermal growth factor may explain the entire mitogenic activity of somatomedin B.
Skeletal Muscle: Length-Dependent Effects of Potentiating Agents
Authors: Lopez J. Rafael , Wanek Laurel A. , Taylor Stuart R.
Published: October 2006

The ability of vertebrate skeletal muscle to contract more vigorously than normal in the presence of potentiating agents depends on the initial length of a muscle cell. Other factors such as the intracellular calcium ion transient, temperature, chemical nature of the potentiating agent, and the ratio of intrinsic twitch to tetanic force influence the degree of contractile potentiation but cannot account for the length dependence. At least part of a muscle cell seems normally less than fully active during contractions not only at short lengths but also at optimal sarcomere lengths.
Muscular Contraction: Kinetics of Crossbridge Attachment Studied by High-Frequency Stiffness Measurements
Authors: Cecchi Giovanni , Griffiths Peter J. , Taylor Stuart
Published: October 2006

Instantaneous stiffness of frog skeletal muscle, an indication of the proportion of attached crossbridges, was determined during the tetanus rise and after a step length change imposed during the tetanus plateau. During the onset of contraction as well as after a step, the ratio of stiffness to force differed from that determined during the tetanus plateau. The data after a step are predicted by the Huxley-Simmons model of muscular contraction, but the results during the rise suggest that a long-lived state may exist between crossbridge attachment and force generation.
Progesterone Administration in Vivo Stimulates Release of Luteinizing Hormone-Releasing Hormone in Vitro
Authors: Ramirez V. D. , Dluzen D. , Lin D.
Published: October 2006

The release of luteinizing hormone-releasing hormone (LHRH) from tissue from the mediobasal hypothalamic-anterior hypothalamic-preoptic area of prepuberal female rats was measured in a perifusion system. Measurements were also made of the concentrations of LHRH in these tissue fragments and of luteinizing hormone in serum obtained when the rats were killed. Four groups of immature rats were studied: intact, ovariectomized, ovariectomized and implanted with estradiol-containing capsules, and ovariectomized rats primed with estradiol and injected with progesterone. The release of LHRH from the tissue of ovariectomized animals was significantly less than that of intact females and was not modified when the ovariectomized rats received estradiol. However, there was a four- to fivefold increase in LHRH release from tissue of ovariectomized rats primed with estradiol when they were killed 6 hours after they received an injection of progesterone. The concentrations of LHRH in tissue and of luteinizing hormone in serum varied among groups and with the time of day that the animals were killed. The interactions among luteinizing hormone, gonadal steroids, and the photoperiod seem to set the appropriate conditions for neural processes triggering a complete and normal release of luteinizing hormone.
Medicine
Authors: Ingelfinger Franz J.
Published: October 2006

Advances in hepatitis and immunology illustrate the influence of basic research and technologic innovation in shaping the past, present, and future of medical care.
Correction of Enzyme Deficiency in Mice by Allogeneic Bone Marrow Transplantation with Total Lymphoid Irradiation
Authors: Slavin S. , Yatziv S.
Published: October 2006

Enzyme deficiency was corrected in mice after allogeneic bone marrow transplantation without occurrence of graft versus host disease. β-Glucuronidase-deficient C3H/HeJ mice were treated with total lymphoid irradiation. Normal bone marrow cells (30 × 10
6
) from BALB/c mice were infused 1 day after total lymphoid irradiation, with resulting stable BALB/c to C3H/HeJ chimeras (> 90 percent circulating donor-type cells) without graft versus host disease. β-Glucuronidase activity increased to normal levels in all chimeras as measured in the liver and in the plasma. Activity was maintained throughout an observation period of 7 months.
Changes in DNA During Meiosis in a Repair-Deficient Mutant (
rad
52) of Yeast
Authors: Resnick M. A. , Kasimos J. N. , Game J. C. , Braun R. J. , Roth R. M.
Published: October 2006

The kinetic patterns of DNA synthesis in wild-type (
RAD
+
) and
rad
52 mutants of yeast, which exhibit high levels of synchrony during meiosis, are comparable. However,
RAD
52 mutants accumulate single-strand breaks in parental DNA during the DNA synthesis period. Thus, the product of the
RAD
52 gene has a role in meiotic DNA metabolism, as well as in the repair of DNA damage during mitotic growth. The observed breaks may be unresolved recombination intermediates.
Biopterin Cofactor Biosynthesis: Independent Regulation of GTP Cyclohydrolase in Adrenal Medulla and Cortex
Authors: Viveros O. Humberto , Lee Ching-Lun , Abou-Donia Martha M. , Nixon Jon C. , Nichol Charles A.
Published: October 2006

Guanosine triphosphate cyclohydrolase, the enzyme that is apparently rate-limiting in biopterin biosynthesis, is increased in adrenal cortex and medulla of rats treated with insulin or reserpine. Denervation and hypophysectomy block the increase in medullary and cortical enzyme activity, respectively, whereas cycloheximide prevents the increase in both tissues. These results provide evidence for induction and regulation of guanosine triphosphate cyclohydrolase.
Microelectronics and Computers in Medicine
Authors: Meindl James D.
Published: October 2006

Microelectronics and computers are in use in virtually every aspect of modern medicine. Computers are used widely in medical research, where an important need is for better microelectronic sensors for data acquisition. In medical practice, data collection from patients as well as subsequent storage, retrieval, and manipulation of data are enhanced by the computer. In medical decision-making computers improve accuracy, increase cost efficiency, and advance understanding of the structure of medical knowledge and of the decision-making process itself. Powerful new noninvasive diagnostic instruments including x-ray tomographic scanners and ultrasonic imaging systems are based on computers. The efficiency and scope of clinical laboratory procedures and advanced analytical instruments are greatly increased by computerization, and careful application of computers has improved the interpretation of diagnostic tests, such as the electrocardiogram, and monitoring of critically ill patients. The powerful sensory, computational, memory, and display capabilities of microcomputer systems and their compact size offer new opportunities to relieve functional deficiencies associated with loss of limbs, paralysis, speech impediments, deafness, and blindness.
Transplantation of Leukemic Bone Marrow Treated with Cytotoxic Antileukemic Antibodies and Complement
Authors: Trigg Michael E. , Poplack David G.
Published: October 2006

The ability of antiserum against murine L1210 leukemia to remove residual leukemia cells from murine bone marrow was investigated. Leukemic marrow was treated in vitro with antiserum and complement and used to hematologically reconstitute mice that had been irradiated with doses lethal to bone marrow. Following infusion of treated leukemic marrow, normal marrow returned without evidence of leukemia. More than 90 percent of the animals have survived for 11 months without untoward effects, suggesting that the technique may be of use in the treatment of acute leukemia in humans.
Coupling of Histone and DNA Synthesis in the Somatic Cell Cycle
Authors: Delegeane Angelo M. , Lee Amy S.
Published: October 2006

The coupling of histone and DNA synthesis was examined in the temperature-sensitive hamster fibroblast cell line K12. By monitoring total cellular histone synthesis at various times after quiescent cells were stimulated to proliferate at permissive and nonpermissive temperatures, a direct correlation was found between the rates of DNA and histone synthesis. Furthermore, when DNA synthesis was blocked by the K12 mutation, histone synthesis was reduced to the basal rate.
Scattered Electrons in Microscopy and Microanalysis
Authors: Ottensmeyer F. P.
Published: October 2006

The use of scattered electrons alone for direct imaging of biological specimens makes it possible to obtain structural information at atomic and near-atomic spatial resolutions of 0.3 to 0.5 nanometer. While this is not as good as the resolution possible with x-ray crystallography, such an approach provides structural information rapidly on individual macromolecules that have not been, and possibly cannot be, crystallized. Analysis of the spectrum of energies of scattered electrons and imaging of the latter with characteristic energy bands within the spectrum produces a powerful new technique of atomic microanalysis. This technique, which has a spatial resolution of about 0.5 nanometer and a minimum detection sensitivity of about 50 atoms of phosphorus, is especially useful for light atom analysis and appears to have applications in molecular biology, cell biology, histology, pathology, botany, and many other fields.
An Inhibitor of the Binding of Thyroid Hormones to Serum Proteins Is Present in Extrathyroidal Tissues
Authors: Chopra Inder J. , Solomon David H. , Chua Teco Guadalupe N. , Eisenberg Jody B.
Published: October 2006

Extrathyroidal tissues of man and the rat contain a potent inhibitor of the binding of thyroid hormones to serum proteins and to an anion-exchange resin. The inhibitor is heat-labile and nondialyzable. It acts by reducing the binding affinity of thyroid hormones to serum proteins, not by reducing the number of binding sites. The tissue inhibitor is similar in several characteristics to an inhibitor described previously in the serum of some critically ill patients, suggesting that the tissue inhibitor may leak into the circulation in severe illnesses.
Heterogeneity in Epidermal Basal Keratinocytes: Morphological and Functional Correlations
Authors: Lavker Robert M. , Sun Tung-Tien
Published: October 2006

Two structurally distinct populations of basal keratinocytes, nonserrated and serrated, were observed in cynomolgus monkey and human palm epidermis. Anatomical location, fine structural features, and kinetic properties suggest that nonserrated cells represent a stem cell population and that serrated cells help anchor the epidermis to the dermis.
Accommodative Defocus Does Not Limit Development of Acuity in Infant
Macaca nemestrina
Monkeys
Authors: Howland Howard , Boothe Ronald G. , Kiorpes Lynne
Published: October 2006

In an experiment with ten macaque monkeys (Macaca nemestrina), a combination of photorefraction and corneal reflex photography was used to measure simultaneously the plane of focus and direction of gaze while they were presented with fixation targets. The monkeys ranged in age from 2 days to 10 weeks. Some of the infants that were less than 1 month old failed to change accommodation to targets at any distance, whereas others showed limited accommodative abilities. The magnitude of the accommodative response of infants older than 4 weeks appeared to be adultlike. Infant monkey's visual acuity improves dramatically after 4 weeks. These results, which show that the improvement in spatial resolution cannot be accounted for by increased accommodative accuracy, parallel those obtained from human infants where accommodative competence is attained by about 4 months of age.
Lysergic Acid Diethylamide (LSD) and Lisuride: Differentiation of Their Neuropharmacological Actions
Authors: White Francis J. , Appel James B.
Published: October 2006

The nonhallucinogenic ergot derivative lisuride exerts many pharmacological effects that are similar to those of its hallucinogenic congener, lysergic acid diethylamide (LSD). Animals trained to discriminate between the presence of one drug and the other can be used to differentiate the actions of these compounds on a neuronal level. The discriminative stimulus effect of LSD (the LSD cue) is similar to that of the serotonin agonist quipazine, whereas the lisuride cue is similar to that of the dopamine agonist apomorphine. These data support the hypothesis that serotonin is intricately involved in the hallucinogenic effects of LSD.
Early Chronic Low-Level Methylmercury Poisoning in Monkeys Impairs Spatial Vision
Authors: Rice Deborah C. , Gilbert Steven G.
Published: October 2006

Five monkeys were treated from birth with oral doses of mercury as methylmercury (50 micrograms per kilogram of body weight per day); concentrations in the blood peaked at 1.2 to 1.4 parts per million; and declined after weaning from infant formula to a steady level of 0.6 to 0.9 part per million. There were no overt signs of toxicity. When tested between 3 and 4 years of age under conditions of both high and low luminance, treated monkeys exhibited spatial vision that was impaired compared with that of control monkeys.
Crystallization of the Tetramer of Histones H3 and H4
Authors: Lattman Eaton , Burlingame Rufus , Hatch Chris , Moudrianakis Evangelos N.
Published: October 2006

Crystals of the histone tetramer (H3-H4)
2
from calf thymus have been grown. The crystals yield x-ray diffraction patterns with Bragg spacings as small as 3.5 angstroms. Crystals grown from two types of preparations have the symmetry of the space group
P
6
1
(or
P
6
5
). The best crystals were grown from histones that had the amino terminal arms removed by mild trypsinization.
Formaldehyde: A Question of Cancer Policy?
Authors: Perera Frederica , Petito Catherine
Published: October 2006

This article describes recent events concerning the assessment and regulation of formaldehyde, and evaluates the scientific data pertaining to the carcinogenicity of this substance in the context of established cancer policies and guidelines. The conclusion is that recent decisions by several federal agencies to defer action to limit human exposure to formaldehyde may be a "test case" for a new, less protective policy concerning the regulation of carcinogenic substances in general.
The Anticancer Agent Adriamycin Can Be Actively Cytotoxic Without Entering Cells
Authors: Triton Thomas R. , Yee Gene
Published: October 2006

The antineoplastic agent adriamycin was coupled to an insoluble agarose support. This material was actively cytotoxic to L1210 cells in culture under conditions in which no free adriamycin could enter the cell. It is concluded that an agent whose principal target was previously thought to be DNA can exert its cytotoxic action solely by interaction at the cell surface.
Size Analysis of Phospholipid Vesicle Preparations
Authors: Nozaki Yasuhiko , Lasič Danilo D. , Tanford Charles , Reynolds Jacqueline A.
Published: October 2006

Gel exclusion chromatography based on the use of Sephacryl S-1000 provides a quick and convenient method for determining the average diameter of phospholipid vesicles and an approximate measure of size heterogeneity.
Cysteamine: a Potent and Specific Depletor of Pituitary Prolactin
Authors: Millard W. J. , Sagar S. M. , Landis D. M. , Martin J. B. , Badger T. M.
Published: October 2006

Cysteamine rapidly reduces the concentration of prolactin in pituitary tissue in vivo and in vitro. The effect is dose-dependent, reversible, and cannot be accounted for by prolactin release. Cysteamine does not appear to exert its effect through dopamine receptors and does not alter lactotrope morphology, as determined by electron microscopy.
Mus poschiavinus
Y Chromosome in the C57BL/6J Murine Genome Causes Sex Reversal
Authors: Eicher Eva M. , Washburn Linda L. , Whitney J. Barry , Morrow Katharine E.
Published: October 2006

When the Y chromosome from
Mus poschiavinus
(Y
POS
) is transferred onto the C57BL/6J genome, XY individuals develop as females with two ovaries, or as hermaphrodites. No XY individual develops normal testes. Although C57BL/6J-Y
POS
XY females are rarely fertile, most hermaphrodites with normal male genitalia sire offspring. Thus, the
Mus poschiavinus
Y chromosome carries a form of the Y-linked testis-determining locus different from that present in the C57BL/6J inbred strain. This gene interacts abnormally with autosomal or X-linked testis-determining loci of the C57BL/6J genome to prevent normal testicular differentiation. Divergence of the Y-linked testis-determining gene may be involved in mammalian speciation.
Biological Diversity in Metastatic Neoplasms: Origins and Implications
Authors: Fidler Isaiah J. , Hart Ian R.
Published: October 2006

Whether neoplasms are unicellular or multicellular in their origin, the process of tumor evolution and progression can rapidly generate biological diversity. Metastases result from the survival and proliferation of specialized subpopulations of cells within the parent tumor. Metastases may have a clonal origin and different metastases may develop from different progenitor cells. However, as with the primary tumor, the origin of metastases is unimportant since the process of tumor evolution and progression can generate biological diversity within and among different metastatic foci.
Type A Behavior and Elevated Physiological and Neuroendocrine Responses to Cognitive Tasks
Authors: Williams Redford B. , Lane James D. , Kuhn Cynthia M. , Melosh William , White Alice D. , Schanberg Saul M.
Published: October 2006

Qualitatively distinct patterns of cardiovascular and neuroendocrine responses were observed in male college students during mental work and during sensory intake task performance. During mental work, Type A (coronary-prone) subjects showed greater muscle vasodilatation and more enhanced secretion of norepinephrine, epinephrine, and cortisol than Type B subjects. During sensory intake, Type A hyperresponsivity was found for testosterone and, among those subjects with a positive family history of hypertension, for cortisol. As a demonstration of combined cardiovascular, sympathetic nervous system, and neuroendocrine hyperresponsivity to specific cognitive tasks in Type A subjects, this study breaks ground in the search for mechanisms mediating the increased coronary disease risk among Type A persons.
A New Perceptual Context-Superiority Effect: Line Segments Are More Visible Against a Figure Than Against a Ground
Authors: Wong Eva , Weisstein Naomi
Published: October 2006

Context, specifically the perceived figure or ground of an ambiguous form that surrounds a diagonal line segment, can influence the discrimination of that line segment even though the physical attributes of the context remain the same during figure-ground reversals. When the line segment was flashed on a region of the form seen as figure, discrimination was twice as accurate as when the line segment was flashed in isolation, and it was at least three times as accurate as when the line segment was flashed on that same region seen as ground.
Impulse Conduction in the Mammalian Brain: Physiological Properties of Individual Axons Monitored for Several Months
Authors: Swadlow Harvey A.
Published: October 2006

Microelectrode recordings were used in conjunction with antidromic activation to monitor impulse conduction along individual mammalian cerebral axons for periods of up to 165 days. Approximately half of the axons studied showed a stable conduction velocity and stable aftereffects of impulse activity. The remaining axons showed slow and progressive increases or decreases in conduction velocity overtime. In these latter axons, changes in the magnitude of the aftereffects of impulse conduction were far less pronounced than were changes in axonal conduction velocity.
Vertical Transmission of Acquired Ulcer Susceptibility in the Rat
Authors: Skolnick Neil J. , Ackerman Sigurd H. , Hofer Myron A. , Weiner Herbert
Published: October 2006

Premature separation of rat pups from their dams greatly increases their susceptibility to restraint-induced gastric erosions. When prematurely separated female rats grow to adulthood and mate with stock males, their normally reared F
1
progeny also have increased susceptibility to restraint-induced erosions. Cross-fostering studies show that prenatal rather than postnatal factors transmit this susceptibility to the F
1
progeny.
Fetal Exposure to Narcotics: Neonatal Sleep as a Measure of Nervous System Disturbance
Authors: Dinges David F. , Davis Miryam M. , Glass Penny
Published: October 2006

Newborn infants, chronically exposed in utero to low doses of methadone with or without concomitant heroin, display more rapid eye movement sleep and less quiet sleep than control infants, while babies fetally exposed to both opiates and nonopiates have less organization of sleep states. Other perinatal factors, such as birth weight and gestational age, are related more to the amount of fetal drug exposure than to the type.
Prenatal Withdrawal from Opiates Interferes with Hatching of Otherwise Viable Chick Fetuses
Authors: Kuwahara M. D. , Sparber S. B.
Published: October 2006

Fetal chicks were made opiate-dependent by injections of
N
-desmethyl-1-α-acetylmethadol into the chorioallantois on day 3 of embryogenesis. The injections had no effect on subsequent hatchability; however, spontaneous fetal motility was significantly depressed. Injection of naloxone caused a significant increase in the motility of the opiate-exposed fetuses but had no effect on control fetuses. That naloxone's effect was an expression of opiate withdrawal and not due to antagonism of depressed motility is also supported by the observation that naloxone significantly reduced the hatchability of opiate-exposed chicks and not of control chicks. Thus the withdrawal of a developing organism from a narcotic may be more deleterious to its survival than continued exposure.
Physical and Social Environment of Newborn Infants in Special Care Units
Authors: Gottfried Allen W. , Wallace-Lande Patricia , Sherman-Brown Susan , King Jeanne , Coen Carolyn , Hodgman Joan E.
Published: October 2006

Infants in newborn intensive and convalescent care units are exposed to large amounts of sensory stimulation of various sorts. Although infants in these units do not lack visual, auditory, and tactile stimulation, they receive relatively infrequent coordinated sensory experiences. Furthermore, there is no diurnal rhythmicity in physical and social stimulation across days.
Controlled Photoperiodic Environments for Food Animals
Authors: Tucker H. Allen , Ringer Robert K.
Published: October 2006

Recent studies suggest that control of daily light exposure regulates reproduction, stimulates body growth, and increases the efficiency of feed utilization and egg and milk yields in several domestic species used for food. Hormones mediate photoperiod-induced changes in these traits. Photoperiod manipulation is a promising method of increasing food production from domestic animals.
Feminizing Effect of Mesonephros on Cultured Differentiating Mouse Gonads and Ducts
Authors: Byskov Anne Grete , Grinsted Jørgen
Published: October 2006

Gonads were removed from fetal mice at about the time that gonadal sex differentiation occurs. The gonads were cultured in vitro with or without their mesonephric tissue. When gonads and ducts removed from sexually undifferentiated fetuses were cultured together, the gonads of both sexes developed female characteristics, whereas gonads cultured without mesonephros developed according to the sex of the fetus from which they were removed. Gonads of sexually differentiated fetuses developed normally whether they were cultured with or without the mesonephros.
Vagotomy Abolishes Cues of Satiety Produced by Gastric Distension
Authors: Gonzalez M. F. , Deutsch J. A.
Published: October 2006

Subdiaphragmatic vagotomy in the rat abolishes responsiveness to gastric distension, one of the cues of satiety. However, vagotomized rats remain responsive to gastric nutrient content, another cue of satiety.
Myelination of Central Nervous System Axons in Tissue Culture by Transplanted Oligodendrocytes
Authors: Seil Fredrick J. , Blank Nathan K.
Published: October 2006

Unmyelinated mouse cerebellar cultures in which oligodendrocyte differentiation had been suppressed by exposure to cytosine arabinoside developed axonal myelin after superimposition of kainic acid-treated cerebellar explants devoid of myelin-receptive axons. The latter explants contained differentiated oligodendrocytes. The operation of a diffusible myelin-stimulating factor was ruled out by the failure of myelination in cytosine arabinoside-exposed explants not in direct contact with oligodendrocyte-containing transplants.
A Coeruleo-Spinal System in Culture
Authors: Marshall K. C. , Pun R. Y. K. , Hendelman W. J. , Nelson P. G.
Published: October 2006

In combined cultures of dissociated spinal neurons and explants from the region of locus coeruleus, rich catecholamine-containing fiber projections from the explant to the surrounding regions of spinal neurons were demonstrated by fluorescence histochemistry. Electrical stimulation of the explant resulted in slow depolarizing responses in many of the spinal neurons. Cells exhibiting this type of response were also usually depolarized by local application of noradrenaline, whereas other, unresponsive neurons usually were not. The depolarizing responses to electrical stimulation and to noradrenaline were both increased by depolarizing current injection and decreased by hyperpolarizing current. These and other data suggest that the depolarizing responses of the spinal neurons to explant stimulation are mediated by noradrenaline released from axons of locus coeruleus neurons.
Diameter of the Cell-to-Cell Junctional Membrane Channels as Probed with Neutral Molecules
Authors: Schwarzmann G. , Wiegandt H. , Rose B. , Zimmerman A. , Ben-Haim D. , Loewenstein W. R.
Published: October 2006

The cell-to-cell channels in the junctions of an insect salivary gland and of insect and mammalian cells in culture were probed with fluorescent molecules-neutral linear oligosaccharides, neutral branched glycopeptides, and charged linear peptides. From the molecular dimensions of the largest permeants and smallest impermeants the permeation-limiting channel diameter was obtained: 16 to 20 angstroms for the mammalian cells and 20 to 30 angstroms for the insect cells.
Intracellular Calcium: Its Release from Granules During Bursting Activity in Snail Neurons
Authors: Sugaya Eiichi , Onozuka Minoru
Published: October 2006

Pentylenetetrazole induces a bursting activity accompanied by intracellular movement of calcium toward the cell membrane in the snail neuron. The calcium appears to originate from the dense lysosome-like granules in the cytoplasm. Pentylenetetrazole markedly depletes the granules of calcium and alters them ultrastructurally from dense granules to lamella type granules.
Cloning Human Fetal γ Globin and Mouse α-Type Globin DNA: Characterization and Partial Sequencing
Authors: Smithies Oliver , Blechl Ann E. , Denniston-Thompson Katherine , Newell Nannette , Richards Julia E. , Slightom Jerry L. , Tucker Phillip W. , Blattner Frederick R.
Published: October 2006

Two globin-related clones isolated from collections of bacteriophages containing unfractionated Eco RI fragments of human and mouse DNA were characterized. Charon3AHs51.1Hbγ includes 2.7 kilobase pairs of human DNA containing a large part of a fetal γ globin chain structural gene; Charon 3AMm30.5 includes 4.7 kilobase pairs of mouse DNA related to α globin. The human fetal γ globin gene has within its coding region two intervening sequences of noncoding DNA, IVS 1 and IVS 2, of approximately 100 and 900 base pairs. Sequence IVS 1 is located at the position of one of the two intervening sequences occurring in adult globin genes; IVS 2 is located at the position of the other.
Cell Lineage Analysis by Intracellular Injection of a Tracer Enzyme
Authors: Weisblat David A. , Sawyer Roy T. , Stent Gunther S.
Published: October 2006

Cell lineages during development of leeches can be ascertained by injection of horseradish peroxidase as a tracer into identified cells at early stages of embryogenesis. The injected embryos continue their normal development, in the course of which horseradish peroxidase is passed on in catalytically active form to the descendants of the injected cell. The distribution of the tracer enzyme and hence of the progeny of the injected cell can then be observed at a later stage of development by staining the preparation for horseradish peroxidase.