bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Classical Conditioning of a Defensive Withdrawal Reflex in
Aplysia californica
Authors: Carew T. J. , Hawkins R. D. , Kandel E. R.
Published: October 2006

The defensive siphon and gill withdrawal reflex of
Aplysia
is a simple reflex mediated by a well-defined neural circuit. This reflex exhibits classical conditioning when a weak tactile stimulus to the siphon is used as a conditioned stimulus and a strong shock to the tail is used as an unconditioned stimulus. The siphon withdrawal component of this reflex can be differentially conditioned when stimuli applied to two different sites on the mantle skin (the mantle shelf and the siphon) are used as discriminative stimuli. The differential conditioning can be acquired in a single trial, is retained for more than 24 hours, and increases in strength with increased trials. Differential conditioning can also be produced within the field of innervation of a single cluster of sensory neurons (the LE cluster) since two separate sites on the siphon skin can serve as discriminative stimuli. The finding that two independent afferent inputs that activate a common set of interneurons and motor neurons can be differentially conditioned restricts the possible cellular loci involved in the associative learning.
The Malaria Parasite Monitored by Photoacoustic Spectroscopy
Authors: Balasubramanian D. , Mohan Rao Ch. , Panijpan B.
Published: October 2006

Noninvasive photoacoustic spectroscopy was used to study the malaria parasites
Plasmodium chabaudi
and
Plasmodium berghei
, their pigment, and ferriprotoporphyrin IX, which is a by-product of the hemoglobin that the parasite ingests. The results indicate that the pigment consists of ferriprotophorphyrin self-aggregates and a noncovalent complex of ferriprotoporphyrin and protein. Spectra of chloroquine-treated parasites reveal in situ interaction between the drug and ferriprotoporphyrin. Chloroquine-resistant parasites, readily distinguishable by this method, appear to degrade hemoglobin only partially.
Cerebellum: Essential Involvement in the Classically Conditioned Eyelid Response
Authors: McCormick David A. , Thompson Richard F.
Published: October 2006

Classical conditioning of the eyelid response in the rabbit was used to investigate the neuronal structures mediating basic associative learning of discrete, adaptive responses. Lesions of the ipsilateral dentate-interpositus nuclei, but not of the cerebellar cortex, abolished the learned eyeblink response. Recordings from these nuclei have revealed neuronal responses related to the learning of the response. Stimulating these recording sites produced the eyelid response. The dentate-interpositus nuclei were concluded to be critically involved in the learning and production of classically conditioned responses.
Mass Discrimination During Prolonged Weightlessness
Authors: Ross H. , Brodie E. , Benson A.
Published: October 2006

Thresholds for mass discrimination under zero gravity in flight were found to be higher by a factor of about 1.8 than those for weight discrimination before flight. This suggests that humans are not as sensitive to inertial mass as they are to weight, and that adaptation can only partially compensate for loss of gravity. Weight discrimination thresholds were raised for 2 or 3 days after flight, suggesting an aftereffect of adaptation to weightlessness.
Comparative Neuroscience Holds Promise for Quiet Revolutions
Authors: Bullock Theodore H.
Published: October 2006

The brain has diversified and advanced in evolution more than any other organ; the variety of nervous systems and behaviors among animal species is thus available for our exploitation. Comparative neuroscience is likely to reach insights so novel as to constitute revolutions in understanding the structure, functions, ontogeny, and evolution of nervous systems. This promise requires pursuit on a wide front, in respect to disciplines and in respect to the species, stages, and states compared. It also requires deliberate concentration on the differences among animals, in addition to the prevailing concern for the basic and common. Neglect of these challenges would be costly. Without due consideration of the neural and behavioral correlates of differences between higher taxa and between closely related families, species, sexes, and stages, we cannot expect to understand our nervous systems or ourselves.
Interaction Between Perceived Self-Motion and Object-Motion Impairs Vehicle Guidance
Authors: Probst Thomas , Krafczyk Siegbert , Brandt Thomas , Wist Eugene R.
Published: October 2006

When one is riding in a vehicle, perceptual thresholds for motion of objects are significantly elevated above those determined under corresponding but simulated conditions in the laboratory without concurrent self-motion perception. Authorities on road traffic accidents should thus consider an additional perceptual time of at least 300 milliseconds for detecting critical changes in headway beyond the usual reaction time. Detection times thus corrected consequently lead to an alteration of our conception of safe intervehicle distances in a convoy. This elevation of thresholds for object-motion during self-motion, with its consequences for visual control of vehicle guidance, can be seen as a disadvantageous side effect of an otherwise beneficial space-constancy mechanism, which provides us with a stable world during locomotion.
Independent Developmental Programs for Two Estrogen-Regulated Genes
Authors: Elbrecht Alex , Lazier Catherine B. , Protter Andrew A. , Williams David L.
Published: October 2006

Measurement of hepatic apolipoprotein II and vitellogenin II messenger RNA during chicken embryogenesis showed that these genes acquire estrogen responsiveness at different stages of development. Sensitive solution hybridization assays with excess complementary DNA showed that apolipoprotein II transcripts were induced to 500 molecules per cell at day 9, whereas induction of vitellogenin II messenger RNA was not found until day 11. Thus, two estrogen regulated genes of common function and coordinately regulated in the adult may be on independent developmental programs.
Human Auditory Frequency-Following Responses to a Missing Fundamental
Authors: Smith James C. , Marsh James T. , Greenberg Steven , Brown Warren S.
Published: October 2006

Both a complex tone perceived as a 365-hertz "missing fundamental" and a 365-hertz pure tone evoked 365-hertz far-field frequency-following responses. Narrow-band masking noise centered at 365 hertz attenuated the responses to the pure tone but not to the complex tone. Results support the concept that perception of the missing fundamental is based on periodic neural activity.
Symbolic Communication Between Two Chimpanzees (
Pan troglodytes
)
Authors: Savage-Rumbaugh E. Sue , Rumbaugh Duane M. , Boysen Sally
Published: October 2006

Through use of learned symbols, two chimpanzees accurately specified 11 foods by name to one another when the food item's identity was known by only one. They could not do this when denied use of the symbols. The chimpanzees then spontaneously requested specific foods of one another by name. Requests resulted in cooperative and reciprocal symbolically mediated food exchange.
Esterase 6 and Reproduction in
Drosophila melanogaster
Authors: Richmond Rollin C. , Gilbert Donald G. , Sheehan Kathy B. , Gromko Mark H. , Butterworth Frank M.
Published: October 2006

A nonspecific carboxylesterase (esterase 6) of
Drosophila melanogaster
shows greater activity in adult males than in females and is highly concentrated in the anterior ejaculatory duct of the reproductive tract of the male. Esterase 6 is depleted in males by copulation and is transferred to females early during copulation as a component of the seminal fluid. That esterase 6 may be involved in a system controlling the timing of remating is suggested by differences in the activity of this enzyme in a strain of
Drosophila
selected for a decrease in time to remating and by differences in the timing of remating in females initially inseminated by males lacking or having active esterase 6.
Mitochondrial DNA Is a Major Cellular Target for a Dihydrodiol-Epoxide Derivative of Benzo[
a
]pyrene
Authors: Backer J. M. , Weinstein I. B.
Published: October 2006

When mammalian cell cultures are exposed for 2 hours to (±)-7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[
a
]pyrene, a mutagenic and carcinogenic derivative of benzo[
a
]pyrene, the extent of covalent modification of mitochondrial DNA is 40 to 90 times greater than that of nuclear DNA. Evidence is presented that this reflects the lipophilic character of the derivative and the very high ratio of lipid to DNA in mitochondria. These results suggest that mitochondrial DNA may be an important cellular target of chemical carcinogens.
The Phylogeny of Prokaryotes
Authors: Fox G. E. , Stackebrandt E. , Hespell R. B. , Gibson J. , Maniloff J. , Dyer T. A. , Wolfe R. S. , Balch W. E. , Tanner R. S. , Magrum L. J. , Zablen L. B. , Blakemore R. , Gupta R. , Bonen L. , Lewis B. J. , Stahl D. A. , Luehrsen K. R. , Chen K. N. , Woese C. R.
Published: October 2006

For the first time a single experimental approach, 16
S
ribosomal RNA sequence characterization, has been used to develop an overview of phylogenetic relationships in the bacterial world. The technique permits the tracing of relationships back to the common ancestor of all extant life. This first glimpse of bacterial phylogeny reveals a world whose roots appear to span more than 3 billion years. A deep phylogenetic split exists among the bacteria, which necessitates their division into two major lines of descent, the archaebacteria and the true bacteria (or eubacteria). It is a general finding that the most ancient bacterial phenotypes are anaerobic, and that aerobic phenotypes have arisen a number of times. Photosynthetic phenotypes are also extremely ancient. Many nonphotosynthetic groups appear to have arisen from photosynthetic ancestry, which is reason to question the generally held belief that the first bacteria were anaerobic heterotrophs. The two ultimate lines of bacterial descent are no more closely related to one another than either is to the cytoplasmic aspect of the eukaryotic cell. However, in that the eukaryotic cell is a phylogenetic chimera, it itself cannot be seen as a line of descent comparable to the two bacterial lines—although some of its individual parts can be so viewed. In this way, the chloroplast and perhaps the mitochondrion are each eubacterial, and at least one ribosomal protein is archaebacterial. A third line of descent that is neither eubacterial nor archaebacterial is represented in the 18
S
ribosomal RNA.
Ornithine Decarboxylase Is Important in Intestinal Mucosal Maturation and Recovery from Injury in Rats
Authors: Lux Gordon D. , Marton Laurence J. , Baylin Stephen B.
Published: October 2006

A transient increase in ornithine decarboxylase activity and polyamine biosynthesis occurs in the intestinal mucosa of the newborn rat in the third week after birth. During this period, there is a rapid conversion of the mucosa from a fetal to a mature adult status. A similar increase in ornithine decarboxylase activity also accompanies the rapid recovery of the mucosa 1 week after an injury is induced by chemotherapy in adult rats. In vivo, α-difluoromethyl ornithine, a highly selective, enzyme-activated, irreversible inhibitor, suppresses these increases in mucosal ornithine decarboxylase and delays both intestinal mucosal maturation and recovery from injury. Thus increased ornithine decarboxylase activity, with the resultant increase in polyamine content, may play an essential role in intestinal mucosal maturation and regeneration in the rat.
Microencapsulated Islets as Bioartificial Endocrine Pancreas
Authors: Lim Franklin , Sun Anthony M.
Published: October 2006

Single implantation of microencapsulated islets into rats with streptozotocin-induced diabetes corrected the diabetic state for 2 to 3 weeks. The microencapsulated islets remained morphologically and functionally intact throughout long-term culture studies lasting over 15 weeks.
Oxidation of Elemental Selenium to Selenite by
Bacillus megaterium
Authors: Sarathchandra S. U. , Watkinson J. H.
Published: October 2006

A strain of
Bacillus megaterium
isolated from soil has been found to oxidize elemental selenium in laboratory cultures to selenite and a trace of selenate (< 1 percent of the selenite). This observation represents an important but hitherto unreported oxidative step in the biological selenium cycle.
Detection of a Milk Factor That Facilitates Folate Uptake by Intestinal Cells
Authors: Colman Neville , Hettiarachchy Navagnana , Herbert Victor
Published: October 2006

Folate binding proteins in milk were tested for their effect on folate absorption. The uptake of bound folate by isolated mucosal cells from the rat small intestine was twice that of free folate and differed from it in being more effective with progression down the small intestine, in not being affected by glucose or Dilantin, in having a higher
p
H optimum, and in being affected by calcium concentration. This milk factor may enhance folate absorption in infants, whose risk of folate deficiency is high.
Corticosterone Increases the Amount of Protein 1, A Neuron-Specific Phosphoprotein, in Rat Hippocampus
Authors: Nestler Eric J. , Rainbow Thomas C. , McEwen Bruce S. , Greengard Paul
Published: October 2006

Corticosterone increased the amount of the neuron-specific phosphoprotein protein 1 in the hippocampus, a brain region rich in corticosterone receptors, but not in several brain regions that contain relatively few corticosterone receptors.
Thyrotropin-Releasing Hormone Improves Cardiovascular Function in Experimental Endotoxic and Hemorrhagic Shock
Authors: Holaday John W. , D'Amato Robert J. , Faden Alan I.
Published: October 2006

Thyrotropin-releasing hormone significantly improved cardiovascular function when it was injected intravenously into conscious rats subjected to experimental endotoxic or hemorrhagic shock. Because thyrotropin-releasing hormone appears to be a "physiologic" opiate antagonist without effects on pain responsiveness, it may provide therapeutic benefits in the treatment of shock or acute hypotension.
Stimulation of Colonic Secretion by Lipoxygenase Metabolites of Arachidonic Acid
Authors: Musch Mark W. , Miller Richard J. , Field Michael , Siegel Marvin I.
Published: October 2006

Both 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and 5-hydroxyeicosatetraenoic acid (5-HETE) increased the short-circuit current (I
sc
) in rabbit colonic mucosa mounted in vitro in Ussing chambers. Measurements of chlorine-36 fluxes indicated that the I
sc
response to 5-HPETE is due to stimulation of active chlorine secretion. 9-, 11-, and 12-HPETE's and leukotrienes C
4
and B
4
produced either very small increases in I
sc
or no increase. In contrast to results in rabbit colon, no HPETE, HETE, or leukotriene was effective in rabbit ileal mucosa. The effects of 5-HPETE in the rabbit colon were unaffected by mepacrine, but could be partially blocked by indomethacin. These results suggest that drugs which block both cyclooxygenase and lipoxygenase may be effective antidiarrheals in patients with colitis.
Resistance to a Malignant Lymphoma in Chickens Is Mapped to Subregion of Major Histocompatibility (
B
) Complex
Authors: Briles W. Elwood , Briles Ruth W. , Taffs Rolf E. , Stone Howard A.
Published: October 2006

A genetic recombinant within the major histocompatibility (
B
) complex of the chicken has revealed the chromosomal subregion effecting resistance to Marek's disease—a malignant lymphoma induced by a herpesvirus. The recombinant,
B
F21-G19
, occurred spontaneously among the progeny of a male heterozygous for resistant
B
F21-G21
and susceptible
B
F19-G19
haplotypes. Exposure to Marek's disease of families segregating for the recombinant showed that this new
F
-
G
arrangement conferred a level of resistance equivalent to that of the resistant parental haplotype. Thus, a gene, or genes, within or closely linked to the
B
-
F
region of the
B
complex appears to be responsible for the observed resistance to Marek's disease.
Shadows of Thought: Shifting Lateralization of Human Brain Electrical Patterns During Brief Visuomotor Task
Authors: Gevins Alan S. , Schaffer Robert E. , Doyle Joseph C. , Cutillo Brian A. , Tannehill Robert S. , Bressler Steven L.
Published: October 2006

Dynamic spatial patterns of correlation of electrical potentials recorded from the human brain were shown in diagrams generated by mathematical pattern recognition. The patterns for "move" and "no-move" variants of a brief visuospatial task were compared. In the interval spanning the P300 peak of the evoked potential, higher correlations of the right parietal electrode with occipital and central electrodes distinguished the no-move task from the move task. In the next interval, spanning the readiness potential in the move task, higher correlations of the left central electrode with occipital and frontal electrodes characterized the move task. These results conform to neuropsychological expectations of localized processing and their temporal sequence. The rapid change in the side and site of localized processes may account for conflicting reports of lateralization in studies which lacked adequate spatial and temporal resolution.
Synaptic Activity Mediates Death of Hypoxic Neurons
Authors: Rothman Steven M.
Published: October 2006

Cultured hippocampal neurons, when exposed to cyanide or an anoxic atmosphere in the early stages of differentiation, were not visibly affected. However, neurons in mature cultures died when exposed to cyanide or anoxia. Cell death could be prevented by treatment with magnesium, which eliminates synaptic activity. These observations suggest that damage in hypoxic neurons is mediated by synaptic activity.
Monocyte Chemotaxis: Stimulation by Specific Exosite Region in Thrombin
Authors: Bar-Shavit Rachel , Kahn Arnold , Wilner George D. , Fenton John W.
Published: October 2006

Human α-thrombin is a potent chemoattractant for human monocytes, with optimum activity occurring at about 10 nanomoles per liter. A variety of thrombins that were chemically modified to alter procoagulant or esterolytic functions showed a similar optimum activity, but complexes of prothrombin or α-thrombin with either antithrombin III or hirudin did not. These findings indicate that the regions in thrombin responsible for monocyte chemotaxis are proximate to those involved in certain protein recognition interactions of α-thrombin (for example, hirudin binding) but are distinct from the catalytic site and from certain exosites required for clotting.
Role for Acetylcholine in Mediating Effects of Light on Reproduction
Authors: Earnest David J. , Turek Fred W.
Published: October 2006

The length of day, or photoperiod, regulates the annual cycle of reproductive activity in the golden hamster. The inhibitory effects of a short-day photoperiod on testicular function were prevented by nighttime, but not daytime, intraventricular injections of carbachol, a cholinergic agonist. Short pulses of light during the night also block short-day induced testicular regression. The findings suggest that acetylcholine may play an important role in the mechanism through which information about the light-dark environment is transferred to the hypothalamic-pituitary-gonadal axis.
Inhibition by Alcohols of the Localization of Radioactive Nitrosonornicotine in Sites of Tumor Formation
Authors: Waddell William J. , Marlowe Carolyn
Published: October 2006

Oral administration of ethanol,
n
-butanol, or
t
-butanol to mice 20 minutes before injection of carbon-14-labeled nitrosonornicotine inhibited the localization of radioactivity in bronchial and salivary duct epithelium and in the liver. Localization of radioactivity in the nasal epithelium and esophagus was not significantly reduced. These alcohols therefore may selectively inhibit tumor formation in three of the five sites where this carcinogen typically acts.
Physiological Correlates of Prolonged Sleep Deprivation in Rats
Authors: Rechtschaffen Allan , Gilliland Marcia A. , Bergmann Bernard M. , Winter Jacqueline B.
Published: October 2006

The issue of whether sleep is physiologically necessary has been unresolved because experiments that reported deleterious effects of sleep deprivation did not control for the stimuli used to prevent sleep. In this experiment, however, experimental and control rats received the same relatively mild physical stimuli, but stimulus presentations were timed to reduce sleep severely in experimental rats but not in controls. Experimental rats suffered severe pathology and death; control rats did not.
Synthesis and Secretion of the Plasmid-Coded Heat-Labile Enterotoxin of
Escherichia coli
in
Vibrio cholerae
Authors: Neill Roger J. , Ivins Bruce E. , Holmes Randall K.
Published: October 2006

Both cholera toxin and heat-labile enterotoxin were made and secreted into culture supernatants by
Vibrio cholerae
containing the enterotoxin plasmid pCG86. Several regulatory mutations in
V. cholerae
that increased or decreased the synthesis of cholera toxin did not affect production of heat-labile enterotoxin. In contrast, a mutation in
V. cholerae
that interfered with the secretion of cholera toxin also decreased the secretion of heat-labile enterotoxin, indicating that they are processed by a common secretory pathway.
Vibrio cholerae
should be useful as a model system for analyzing the secretion of true extracellular proteins by Gram-negative bacteria.
Local Cerebral Blood Flow Increases During Auditory and Emotional Processing in the Conscious Rat
Authors: LeDoux Joseph E. , Thompson Michael E. , Iadecola Costantino , Tucker Lewis W. , Reis Donald J.
Published: October 2006

Local cerebral blood flow was measured in rats by the
14
C-labeled iodoantipyrine technique with quantitative autoradiography during the processing of environmental stimuli. Presentation of a tone increased blood flow in the auditory but not the visual pathway. When the animal had previously been conditioned to fear the tone, blood flow additionally increased in the hypothalamus and amygdala. Local cerebral blood flow can thus be used to detect patterns of cerebral excitation associated with transient (30- to 40-second) mental events in experimental animals.
Multigene Family for Sarcomeric Myosin Heavy Chain in Mouse and Human DNA: Localization on a Single Chromosome
Authors: Leinwand Leslie A. , Fournier R. E. K. , Nadal-Ginard Bernardo , Shows Thomas B.
Published: October 2006

Cloned myosin heavy chain DNA probes from rat and human were hybridized to restriction endonuclease digests of genomic DNA from somatic cell hybrids and their parental cells. The mouse myosin heavy chain genes detectable by this assay were located on chromosome 11, and three different human sarcomeric myosin heavy chain genes were mapped to the short arm of chromosome 17. A synteny between myosin heavy chain and two unrelated markers, thymidine kinase and galactokinase, was found to be preserved in the rodent and human genomes.
Decrease of Human Serum Fucosyltransferase as an Indicator of Successful Tumor Therapy
Authors: Bauer Christian H. , Reutter Werner G. , Erhart Klaus Peter , Köttgen Eckart , Gerok Wolfgang
Published: October 2006

Surgical removal of colon carcinomas leads to a decrease in the rate of incorporation of [
14
C]fucose into its endogenous acceptor in human serum; normal incorporation rates are attained within 14 days. A similar time course has been determined for α
2
- and α
3
-fucosyltransferase when either desialo- or desialodegalactofetuin are employed as exogenous acceptors. A correlation has also been seen between transferase activity and the therapeutic response of patients with breast cancer. These results indicate that the determination of fucosyltransferase activity can facilitate the diagnosis of neoplasia, and the success of surgery, chemotherapy, or radiation.
Physiologically Important Stabilization of DNA by a Prokaryotic Histone-Like Protein
Authors: Stein Diana B. , Searcy Dennis G.
Published: October 2006

The thermophilic mycoplasma
Thermoplasma acidophilum
has tightly bound to its DNA a protein that closely resembles the histones of eukaryotes. DNA associated with this protein is more stable than free DNA against thermal denaturation by about 40°C, as shown in both native nucleoprotein and in hybrid nucleoprotein reconstituted in vitro with calf DNA. Since only about 20 percent of the DNA in this organism is associated with the histone-like protein, we suggest that its physiological function is to prevent complete separation of the DNA strands during brief exposures of the organism to denaturing conditions, and thus to facilitate rapid renaturation when normal environmental conditions return.
Regulation of Macrophage Tumoricidal Function: A Role for Prostaglandins of the E Series
Authors: Schultz Richard M. , Pavlidis Nicholas A. , Stylos William A. , Chirigos Michael A.
Published: October 2006

Exogenously added prostaglandins E
1
and E
2
, but not F
2α
, inhibited the tumoricidal activity of interferon-activated macrophages of mice. A role for adenosine 3′,5′-monophosphate (cyclic AMP) in modulating macrophage functional activity was suggested because prostaglandins of the E series increase intracellular concentrations of cyclic AMP in macrophages and because treatment of interferon-activated macrophages with dibutyryl cyclic AMP consistently inhibits expression of cytotoxicity. Since the activated macrophage releases high concentrations of prostaglandin E
2
, it is postulated that this prostaglandin could act locally in negative feedback inhibition to limit cell activities.
X-Linked Ichthyosis: Increased Blood Cholesterol Sulfate and Electrophoretic Mobility of Low-Density Lipoprotein
Authors: Epstein Ervin H. , Krauss Ronald M. , Shackleton Cedric H. L.
Published: October 2006

Plasma cholesterol sulfate concentration is increased in patients with recessive X-linked ichthyosis, a disease in which steroid sulfatase activity is absent. In these patients, cholesterol sulfate is found primarily in the low-density lipoprotein fraction of plasma, and the electrophoretic mobility of these lipoproteins is greatly increased.
Epidermal Growth Factor Is a Major Growth-Promoting Agent in Human Milk
Authors: Carpenter Graham
Published: October 2006

Human milk stimulates DNA synthesis in cell cultures in which growth has been arrested. The mitogenic activity of milk is neutralized by the addition of antibody to human epidermal growth factor. The results identify epidermal growth factor as a major growth-promoting agent in breast milk.
An Endocrine Approach to the Control of Epidermal Growth: Serum-Free Cultivation of Human Keratinocytes
Authors: Maciag T. , Nemore R. E. , Weinstein R. , Gilchrest B. A.
Published: October 2006

Human keratinocytes, derived from the skin of newborns and of adults, were grown in the complete absence of serum, in a hormone-supplemented medium on fibronectin-coated cell culture dishes at low seed density. The cell culture medium consisted of Medium 199 containing epidermal growth factor, triiodothyronine, hydrocortisone, Cohn fraction IV, insulin, transferrin, bovine brain extract, and trace elements. Removal of the brain extract from the hormone supplement had a greater negative impact on proliferation of the keratinocyte cultures than did the removal of epidermal growth factor, hydrocortisone, and triiodothyronine or Cohn fraction IV. The growth of keratinocytes in this hormone-supplemented medium suggests that control of keratinocyte growth depends in large part on endocrine stimulation by other body organs, including the brain.
Hybridoma Produces Protective Antibodies Directed Against the Sporozoite Stage of Malaria Parasite
Authors: Yoshida Nobuko , Nussenzweig Ruth S. , Potocnjak Pedro , Nussenzweig Victor , Aikawa Masamichi
Published: October 2006

Hybrid cells secreting antibodies against sporozoites of Plasmodium berghei were obtained by fusion of plasmacytoma cells with immune murine spleen cells. The monoclonal antibodies bound to a protein with an apparent molecular weight of 44,000 (Pb44), which envelopes the surface membrane of sporozoites. Incubation of sporozoites in vitro with antibodies to Pb44 abolished their infectivity.
Synthesis of Human Plasminogen by the Liver
Authors: Raum Donald , Marcus Deborah , Alper Chester A. , Levey Raphael , Taylor Paul D. , Starzl Thomas E.
Published: October 2006

Genetic types of plasminogen were determined from a donor and a recipient before and after hepatic homotransplantation. Examination of the plasminogen types demonstrated that the liver is the principal site of synthesis of human plasminogen.
Vascular Permeation of Platelet Factor 4 After Endothelial Injury
Authors: Goldberg Itzhak D. , Stemerman Michael B. , Handin Robert I.
Published: October 2006

Antibody to platelet factor 4 was used to demonstrate permeation of this factor into the blood vessel wall after endothelial injury in rabbits. The presence of platelet factor 4 antigen in the vessel wall after removal of the endothelium was shown by immunofluorescence 10 and 30 minutes after injury but not 240 minutes afterward. This study demonstrates that factors carried by platelets can enter the vessel wall and that the movement of these platelet products into the vasculature is a short-lived, self-limiting process.
Computers, Health Care, and Medical Information Science
Authors: Lincoln Thomas L. , Korpman Ralph A.
Published: October 2006

The clinical laboratory is examined as a microcosm of the entire health care delivery system. The introduction of computers into the clinical laboratory raises issues that are difficult to resolve by the methods of information science or medical science applied in isolation. The melding of these two disciplines, together with the contributions of other disciplines, has created a new field of study called medical information science. The emergence of this new discipline and some specific problem-solving approaches used in its application in the clinical laboratory are examined.
Living Tissue Formed in Vitro and Accepted as Skin-Equivalent Tissue of Full Thickness
Authors: Bell Eugene , Ehrlich H. Paul , Buttle David J. , Nakatsuji Takako
Published: October 2006

Living skin-equivalent grafts consisting of fibroblasts cast in collagen lattices and seeded with epidermal cells were successfully grafted onto the donors of the cells. The grafts were vascularized, did not evoke a homograft reaction, inhibited wound contraction, filled the wound space, and persisted.
Micromolar Calcium Stimulates Proteolysis and Glutamate Binding in Rat Brain Synaptic Membranes
Authors: Baudry Michel , Bundman Marsha C. , Smith Elizabeth K. , Lynch Gary S.
Published: October 2006

Incubation of cortical synaptic membranes with low concentrations of calcium resulted in a decrease in the amount of a high-molecular-weight doublet protein and an increase in the sodium-independent binding of glutamate. Both effects were blocked by the thiol protease inhibitor leupeptin. These results suggest that calcium-induced proteolysis of membrane components regulates the number of glutamate receptors in neuronal membranes.
Natural Killer Cells: Their Roles in Defenses Against Disease
Authors: Herberman Ronald B.. , Ortaldo John R.
Published: October 2006

Natural killer cells are a recently discovered subpopulation of lymphoid cells that are present in most normal individuals of a range of mammalian and avian species. Natural killer cells have spontaneous cytolytic activity against a variety of tumor cells and some normal cells, and their reactivity can be rapidly augmented by interferon. They have characteristics distinct from other types of lymphoid cells and are closely associated with large granular lymphocytes, which comprise about 5 percent of blood or splenic leukocytes. There is increasing evidence that natural killer cells, with the ability to mediate natural resistance against tumors in vivo, certain virus and other microbial diseases, and bone marrow transplants, may play an important role in immune surveillance.
Chemical Triggering of Reproduction in
Microtus montanus
Authors: Berger Patricia J. , Negus Norman C. , Sanders Edward H. , Gardner Pete D.
Published: October 2006

In a replicated experiment, nonbreeding winter populations of
Microtus montanus
were given supplements of rolled oats coated with 6-methoxybenzoxazolinone, a naturally occurring plant derivative. After 3 weeks of this feeding regime, samples from the populations demonstrated a high incidence of pregnancy in females and testicular hypertrophy in males. Control populations receiving rolled oats coated only with the solvent showed no reproductive activity. These results demonstrate that the presence of 6-methoxybenzoxazolinone in the plant food resource acts as the ultimate cue to trigger reproductive effort in
Microtus montanus
.
Hemin Lyses Malaria Parasites
Authors: Orjih Augustine U. , Banyal H. S. , Chevli Rekha , Fitch Coy D.
Published: October 2006

Malaria parasites isolated from mouse erythrocytes are lysed by ferriprotoporphyrin IX chloride (hemin) or by a chloroquine-hemin complex in amounts that could be produced by release of less than 0.1 percent of the heme in erythrocytic hemoglobin. This effect of hemin may explain the protection against malaria provided by thalassemia and other conditions causing intracellular denaturation of hemoglobin. The toxicity of the chloroquine-hemin complex may explain the selective antimalarial action of chloroquine.
Autoimmune Encephalomyelitis: Simultaneous Identification of T and B Cells in the Target Organ
Authors: Traugott Ute , Shevach E. , Chiba J. , Stone S. H. , Raine C. S.
Published: October 2006

Monoclonal antibodies to guinea pig T cells and antibodies to guinea pig immunoglobulin G were used in immunofluorescence studies to identify T and B cells in central nervous system tissue from guinea pigs with acute autoimmune encephalomyelitis. T cells appeared before B cells and were distributed within the white matter parenchyma, while B cells remained in perivascular spaces.
Variation of Influenza A, B, and C Viruses
Authors: Palese Peter , Young James F.
Published: October 2006

Influenza is caused by highly variable RNA viruses belonging to the orthomyxovirus group. These viruses are capable of constantly changing the genes coding for their surface proteins as well as for their nonsurface proteins. The mechanisms responsible for these changes in type A influenza viruses include recombination (reassortment) of genes among strains, deletions and insertions in genes, and, frequently, point mutations. In addition, old strains may reappear in the population. Influenza viruses of types B and C appear to vary to a lesser degree. The mechanisms responsible for changes in these viruses are not well characterized.
Autoantibodies to Insulin Receptor Spontaneously Develop as Anti-Idiotypes in Mice Immunized with Insulin
Authors: Shechter Yoram , Maron Ruth , Elias Dana , Cohen Irun R.
Published: October 2006

Mice immunized with insulin developed antibodies to both insulin and the insulin receptor. The antibodies to insulin receptor displaced labeled insulin from insulin receptors and mimicked the actions of insulin in stimulating the oxidation of glucose and its incorporation into lipids, and in inhibiting lipolysis. The antibodies to insulin receptor could be blocked by or bound to the antibodies to insulin, and therefore were identified as anti-idiotypes. Thus, immunization against a hormone may activate spontaneously an idiotype-anti-idiotype network resulting in antibodies to the hormone receptor.
Is the Acetylcholine Receptor a Rabies Virus Receptor?
Authors: Lentz Thomas L. , Burrage Thomas G. , Smith Abigail L. , Crick Joan , Tignor Gregory H.
Published: October 2006

Rabies virus was found on mouse diaphragms and on cultured chick myotubes in a distribution coinciding with that of the acetylcholine receptor. Treatment of the myotubes with α-bungarotoxin and
d
-tubocurarine before the addition of the virus reduced the number of myotubes that became infected with rabies virus. These findings together suggest that acetylcholine receptors may serve as receptors for rabies virus. The binding of virus to acetylcholine receptors, which are present in high density at the neuromuscular junction, would provide a mechanism whereby the virus could be locally concentrated at sites in proximity to peripheral nerves facilitating subsequent uptake and transfer to the central nervous system.
Iodine-125-Labeled Triiodothyronine in Rat Brain: Evidence for Localization in Discrete Neural Systems
Authors: Dratman Mary B. , Futaesaku Yataka , Crutchfield Floy L. , Berman Nancy , Payne Bertram , Sar Madhabananda , Stumpf Walter E.
Published: October 2006

Autoradiograms prepared from adult rat brains demonstrate that nerve cells and neuropil in different brain regions selectively concentrate and retain intravenously administered triiodothyronine, by mechanisms susceptible to saturation with excess triiodothyronine. A neuroregulatory role for thyroid hormones, strongly supported by the observations, may account for their marked effects on behavior and the activity of the autonomic nervous system.
Histone Proteins in HeLa S
3
Cells Are Synthesized in a Cell Cycle Stage Specific Manner
Authors: Marashi F. , Baumbach L. , Rickles R. , Sierra F. , Stein J. L. , Stein G. S.
Published: October 2006

The synthesis of histone proteins in G
1
and S phase HeLa S
3
cells was examined by two-dimensional electrophoretic fractionation of nuclear and total cellular proteins. Newly synthesized histones were detected only in S phase cells. Histone messenger RNA sequences, as detected by hybridization with cloned human histone genes, were present in the cytoplasm of S phase but not G
1
cells.
Perinatal Undernutrition Reduces Alpha and Beta Adrenergic Receptor Binding in Adult Rat Brain
Authors: Keller Elizabeth A. , Munaro Norma I. , Orsingher Otto A.
Published: October 2006

Specific alpha and beta receptor binding is significantly reduced in the brains of adult rats that were undernourished perinatally. From kinetic studies it may be concluded that this effect is the result of a diminished number of binding sites, not changes in receptor affinity.
Corticosterone: A Critical Factor in an Opioid Form of Stress-Induced Analgesia
Authors: MacLennan A. John , Drugan Robert C. , Hyson Richard L. , Maier Steven F. , Madden John , Barchas Jack D.
Published: October 2006

The finding that some opioid-mediated forms of stress-induced analgesia are antagonized by hypophysectomy and dexamethasone has led to the suggestion that β-endorphin, released from the pituitary, may mediate these analgesic reactions. "Long-term analgesia" (an opioid-mediated form of stress-induced analgesia), which is blocked by dexamethasone and hypophysectomy, was also blocked by adrenalectomy and reinstated with corticosterone therapy. Corticosterone is proposed to play a permissive role in long-term analgesia and to be a critical hormone mediating this phenomenon.
Cytochrome P-450-Dependent Monooxygenases in Olfactory Epithelium of Dogs: Possible Role in Tumorigenicity
Authors: Dahl Alan R. , Hadley William M. , Hahn Fletcher F. , Benson Janet M. , McClellan Roger O.
Published: October 2006

The respiratory tract epithelium of dogs, from the nose to the lungs, was examined for cytochrome P-450 and associated biotransformation activities. In the ethmoturbinates, where olfactory epithelium is located, the amount of cytochrome P-450 was comparable to that in the liver, when measured on the basis of activity per milligram of microsomal protein. The rest of the nasal region also contained large quantities of cytochrome P-450. The presence of these enzymes in the nose may be important in chemical-induced tumorigenesis. The nasal carcinogen hexamethylphosphoramide was shown to be metabolized by nasal microsomal enzymes to another nasal carcinogen, formaldehyde.
Calcium and Age in Fibroblasts from Control Subjects and Patients with Cystic Fibrosis
Authors: Shapiro Burton L. , Lam Louis F-H.
Published: October 2006

Intracellular calcium increases significantly as human fibroblasts age in culture. The calcium increase occurs 5 to 6 weeks (passages) earlier and is significantly greater in fibroblasts from subjects with cystic fibrosis in comparison with cells from control subjects. Intracellular calcium, which is thought to be a pathogenetic factor in cystic fibrosis, may also be a meaningful marker in cell aging.
Sodium Transport Inhibition by Amiloride Reduces Basolateral Membrane Potassium Conductance in Tight Epithelia
Authors: Davis C. William , Finn Arthur L.
Published: October 2006

In toad and frog urinary bladder, electrophysiological data suggest that inhibition of transepithelial sodium transport by mucosal amiloride results in a decrease in basolateral membrane conductance. These results were confirmed by showing that amiloride addition caused a decrease in basolateral membrane potassium permeability.
Tumorigenesis at a Predetermined Oral Site After One Intraperitoneal Injection of
N
-Nitroso-
N
-Methylurea
Authors: Konstantinidis Antonis , Smulow Jerome B. , Sonnenschein Carlos
Published: October 2006

Tumors in the soft tissues of the oral cavity of rats developed at predetermined sites as a result of a combination of an intraperitoneal injection of a direct-acting carcinogen.
N
-nitroso-
N
-methylurea, and a continuous irritation of the buccal mucosa by a stainless steel wire. The incidence of histologically malignant tumors was significantly higher in the irritated area than in any other area of the body. These results constitute evidence for a carcinogenic mechanism whereby the cells that develop into tumors may require the promotional effect of a nonspecific, nonmutagenic stimulus.
Tritiated Imipramine Binding Sites Are Decreased in the Frontal Cortex of Suicides
Authors: Stanley Michael , Virgilio Joanne , Gershon Samuel
Published: October 2006

Binding characteristics of tritiated imipramine were determined in the frontal cortex of suicides and well-matched controls. Maximal binding was significantly lower in brains from the suicides. This finding is consistent with reports of decreased tritiated imipramine binding in the platelets of patients diagnosed as having a major affective disorder.
Tonotopic Organization of the Human Auditory Cortex
Authors: Romani Gian Luca , Williamson Samuel J. , Kaufman Lloyd
Published: October 2006

Neuromagnetic measurements of responses to auditory stimuli consisting of pure tones amplitude-modulated at a low frequency have been used to deduce the location of cortical activity. The evoked field source systematically increased in depth beneath the scalp with increasing frequency of the tone. The tonotopic progression can be described as a logarithmic mapping.
Activity-Dependent K
+
Accumulation in the Developing Rat Optic Nerve
Authors: Connors Barry W. , Ransom Bruce R. , Kunis David M. , Gutnick Michael J.
Published: October 2006

Potassium-sensitive microelectrodes were used to study activity-dependent changes of extracellular potassium ion concentration ([K
+
]
o
) in rat optic nerves of different postnatal ages (1 day to adulthood). The maximum level to which [K
+
]
o
rose with optimal frequencies of stimulation depended on age: mean maximum evoked [K
+
]
o
was 17.2 m
M
in 1- to 3-day-old optic nerves and 9.8 m
M
in adult nerves. The ceiling [K
+
]
o
seen in immature optic nerves, which is uniquely large for a mammalian central nervous system structure, may result from a relatively enhanced rate of evoked K
+
release.
Loss of Retinal X-cells in Cats with Neonatal or Adult Visual Cortex Damage
Authors: Tong Lillian , Spear Peter D. , Kalil Ronald E. , Callahan Eileen C.
Published: October 2006

Recordings were made from single retinal ganglion cell somas in cats whose visual cortical areas 17 and 18 were damaged on the day of birth or in adulthood. Neonatal lesions produced a 78 percent loss of X-cells in the retina, while lesions made in adulthood produced a 22 percent loss. Y-cells and W-cells were unaffected. This retinal abnormality needs to be considered when interpreting studies of behavioral deficits and neural mechanisms of recovery after damage to the visual cortex.
Asian Bull Elephants: Flehmen-Like Responses to Extractable Components in Female Elephant Estrous Urine
Authors: Rasmussen Lois E. , Schmidt Michael J. , Henneous Roger , Groves Douglas , Daves G. Doyle
Published: October 2006

Flehmen-like responses (urine tests) are one of the characteristic behavioral reactions of male Asian elephants (
Elephas maximus
) to cow elephants in estrus. Components of the urine of estrous cow elephants were extracted with organic solvents and partially purified by chromatography and shown to evoke Flehmen-like responses when they were presented to adult bulls.
Agricultural Research and Third World Food Production
Authors: Plucknett Donald L. , Smith Nigel J. H.
Published: October 2006

By the close of this century the world may have to feed as many as 2 billion additional people. Most of them will be born in developing countries, especially in marginal lands ill-suited for food production. This article focuses on efforts by the International Agricultural Research Centers to increase food production in the Third World and addresses the social and ecological issues raised by the introduction of high-yielding varieties into fertile Third World lands and describe how varieties are being tailored for introduction into marginal areas.
Subperiosteal Expansion and Cortical Remodeling of the Human Femur and Tibia with Aging
Authors: Ruff Christopher B. , Hayes Wilson C.
Published: October 2006

Increases with aging in subperiosteal dimensions and second moments of area (measures of bending and torsional rigidity) in femoral and tibial cross sections are documented in an archeological sample from the American Southwest. Significant differences between cross-sectional sites and between sexes in the pattern of cortical remodeling with age are also present. These differences appear to be related to variations in the stress or strain levels in different regions of the femur and tibia which result from in vivo mechanical loadings of the lower limb.
Initiation of Endochondral Calcification Is Related to Changes in the Redox State of Hypertrophic Chondrocytes
Authors: Shapiro Irving M. , Golub Ellis E. , Kakuta Saburo , Hazelgrove John , Havery Julie , Chance Britton , Frasca Peter
Published: October 2006

The level of pyridine nucleotides (NADH and NAD
+
) in the mineralizing growth plate of the chick was ascertained by high-resolution scanning microfluorimetry and biochemical analysis. Scanning electron microscopy and light microscopy were used to relate the concentrations of NADH and NAD
+
to stages of chondrocyte maturation. A dramatic increase was found in the relative concentration of reduced pyridine nucleotides in the hypertrophic zone. On either side of this zone, in proliferating and calcifying cartilage, there was a decrease in NADH fluorescence, and the NADH/NAD
+
ratio was depressed. The finding that NADH accumulated in the tissue zone associated with the earliest deposition of bone mineral supports the hypothesis that a change in the redox state initiates tissue mineralization.
Cystine Transport Is Defective in Isolated Leukocyte Lysosomes from Patients with Cystinosis
Authors: Gahl W. A. , Bashan N. , Tietze F. , Bernardini I. , Schulman J. D.
Published: October 2006

The activity of a cystine transport system in lysosomes prepared from the leukocytes of patients with cystinosis was found to be deficient. In normal subjects, this system was resistant to
N
-ethylmaleimide and demonstrated saturation kinetics. Lysosomes from individuals heterozygous for cystinosis demonstrated a reduced maximum velocity for cystine egress from lysosomes. The rate of cystine escape from normal lysosomes was enhanced by adenosine triphosphate. The availability of normal and mutant lysosomes provides a means of investigating mechanisms of amino acid transport across lysosomal membranes.