bluuebunny/crossref_metadata_2025 huggingface dataset:
Active Shortening Retards the Decline of the Intracellular Calcium Transient in Mammalian Heart Muscle
Authors: Housmans Philippe R. , Lee Norman K. M. , Blinks John R.
Published: October 2006

When active shortening of the cat papillary muscle was allowed at any time during a contraction, the intracellular concentration of free calcium ions, detected with the calcium-sensitive bioluminescent protein aequorin, was higher than at comparable times in isometric twitches. The difference was not attributable to the differences of length involved or to motion artifacts, and must have been related to the act of shortening or the difference in force development in the two types of contractions. This observation and the phenomenon of shortening deactivation are both consistent with the hypothesis that attachment of cross bridges increases the affinity of the myofilaments for calcium ions.
A Pheromone Influences Larval Development in the Nematode
Caenorhabditis elegans
Authors: Golden James W. , Riddle Donald L.
Published: October 2006

A
Caenorhabditis
-specific pheromone and the food supply influence both entry into and exit from a developmentally arrested juvenile stage called the dauer larva. The pheromone increases the frequency of dauer larva formation and inhibits recovery but does not affect adult behavior such as chemotaxis and egg laying. The fatty acid-like pheromone has been partially purified and characterized by a new bioassay. If similar developmental control mechanisms are used by parasitic nematodes, such mechanisms might be exploited to develop highly selective anthelmintic agents.
Circulation of H
+
and K
+
Across the Plasma Membrane Is Not Obligatory for Bacterial Growth
Authors: Harold Franklin M. , Van Brunt Jennifer
Published: October 2006

Streptococcus faecalis
grows normally in the presence of gramicidin and other ionophores under conditions such that there is no gradient of
p
H or of electrical potential across the plasma membrane and that currents of H
+
, K
+
, and Na
+
are short-circuited. Growth requires a rich medium, a slightly alkaline
p
H, and a high concentration of external K
+
. The proton circulation maintains the cytoplasmic
p
H and pools of ions and other metabolites but is not obligatory for biosynthetic functions including DNA replication, cell division, or assembly of the structural framework of the cell.
Ornithine Decarboxylase: Essential in Proliferation But Not Differentiation of Human Promyelocytic Leukemia Cells
Authors: Luk Gordon D. , Civin Curt I. , Weissman Robert M. , Baylin Stephen B.
Published: October 2006

The ornithine decarboxylase inhibitor DL-α-difluoromethyl ornithine inhibited a proliferation-associated increase in ornithine decarboxylase activity in cultured human promyelocytic leukemia cells, resulting in a marked suppression of cell proliferation and subsequent cell loss. It also inhibited increases in ornithine decarboxylase activity associated with the phorbol ester-induced conversion of promyelocytic HL-60 cells to monocyte-like cells and the retinoic acid-induced conversion to granulocyte-like cells. However, the inhibition of ornithine decarboxylase activity did not prevent cellular differentiation. These results suggest that polyamine biosynthesis has a specific role in cell proliferation rather than in inducing differentiation that is not accompanied by proliferation. The data also demonstrate that cessation of proliferation in HL-60 cells is not necessarily associated with differentiation.
Preferential Synthesis of the G1m(1) Allotype of IgG1 in the Central Nervous System of Multiple Sclerosis Patients
Authors: Salier Jean-Philippe , Goust Jean-Michel , Pandey Janardan P. , Fudenberg H. Hugh
Published: October 2006

Quantitations of the G1m(1) and G1m(3) allotypic determinants of human immunoglobulin G were performed by radioimmunoassay on cerebrospinal fluid and serum samples from patients with multiple sclerosis and from patients with other neurological disorders. In multiple sclerosis patients that were heterozygous for these determinants, G1m(1) concentration in the cerebrospinal fluid was greatly increased-reflected by an increased ratio of G1m(1) to G1m(3)-in comparison with that of patients with other neurological disorders. These results suggest that in the heterozygous multiple sclerosis patients, most of the plasma cells in the central nervous system that secrete oligoclonal immunoglobulin G preferentially synthesize G1m(1) IgG1 molecules.
Complete Amino Acid Sequence of Urotensin I, a Hypotensive and Corticotropin-Releasing Neuropeptide from
Catostomus
Authors: Lederis K. , Letter A. , McMaster D. , Moore G. , Schlesinger D.
Published: October 2006

Urotensin I, purified from extracts of the urophysis of a teleost fish (
Catostomus commersoni
), exhibits potent hypotensive activity (mammals and birds) and corticotropin-releasing activity (both fish and mammals). The primary structure of this 41-residue peptide was determined to be H-Asn-Asp-Asp-Pro-Pro-Ile-Ser-Ile-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Asn-Met-Ile-Glu-Met-Ala-Arg-Ile-Glu-Asn-Glu-Arg-Glu-Gln-Ala-Gly-Leu-Asn-Arg-Lys-Tyr-Leu-Asp-Glu-Val-NH2. Extraction with 0.1
N
HCl at 100°C cleaves the amino-terminal tripeptide, yielding a fully active analog, urotensin I(4-41). The amino acid sequence was confirmed by measuring the biological activity of synthetic urotensin I(4-41). Urotensin I exhibits a striking sequence homology with ovine corticotropin-releasing factor and with frog sauvagine. These three peptides exhibit similar activities in biological test systems.
Nonvolatile Mutagens in Drinking Water: Production by Chlorination and Destruction by Sulfite
Authors: Cheh Albert M. , Skochdopole Jill , Koski Paul , Cole Larry
Published: October 2006

In concentrates of water produced in a laboratory simulation of a drinking water treatment process, direct-acting, nonvolatile mutagens were readily detected by means of the Ames
Salmonella
test. The mutagens were shown to be produced by the chlorination process. Treatment of the water with chloramine resulted in less mutagenic activity than treatment with free chlorine. Dechlorination of drinking water with sulfite sharply reduced the mutagenic activity. Treatment with sulfur dioxide is proposed as an effective, inexpensive method of reducing the direct-acting mutagenic activity of drinking water and of aqueous industrial effluents.
Teratogenic Effects of Alcohol in Humans and Laboratory Animals
Authors: Streissguth Ann Pytkowicz , Landesman-Dwyer Sharon , Martin Joan C. , Smith David W.
Published: October 2006

The teratogenicity of alcohol has been demonstrated in humans through clinical studies, behavioral studies, and epidemiologic studies, and in animals through controlled laboratory experiments. In humans exposed to alcohol during gestation the effects can range from fetal alcohol syndrome in some offspring of chronic alcoholic women to reduced average birth weight in offspring of women reporting an average consumption of two to three drinks or more per day. The behavioral effects of such exposure may range from mental retardation in children with fetal alcohol syndrome to milder developmental and behavioral effects in infants born to social drinkers. In animals, exposure to alcohol in utero may result in death, malformation, and growth deficiency as well as behavioral and developmental abnormalities. The mechanisms of impairment and related risk factors are yet to be elucidated.
Autoantibodies Against Axonal Neurofilaments in Patients with Kuru and Creutzfeldt-Jakob Disease
Authors: Sotelo J. , Gibbs C. J. , Gajdusek D. C.
Published: October 2006

The serums of some patients with subacute spongiform encephalopathies contain an autoantibody in high titer against a normal fibrillar protein within the axon of mature central neurons in culture. The morphological features of this neurofilament, as demonstrated by immunofluorescence and immunoperoxidase staining, and the partial characterization of the antibody are described. The detection of this hetero-specific autoantibody is the first evidence of an immune reaction in the spongiform encephalopathies.
Hormonal Requirements for Growth of Arterial Smooth Muscle Cells in vitro: An Endocrine Approach to Atherosclerosis
Authors: Weinstein Robert , Stemerman Michael B. , Maciag Thomas
Published: October 2006

In this study the hormonal requirements for the growth of arterial smooth muscle cells in vitro were determined. A serum-free, biochemically defined medium, supplemented with the relevant hormones, permitted proliferation and propagation of normal diploid mammalian arterial smooth muscle cells. Serum-free, hormone-supplemented cultures spontaneously formed atherosclerotic plaque-like nodules. Thus atherosclerosis may be mediated by a complex endocrine system.
Cloning of Naturally Occurring Mixed Infections of Malaria Parasites
Authors: Rosario Virgilio
Published: October 2006

Clones have been established from a cultured isolate of
Plasmodium falciparum
characterized by two electrophoretic forms of glucose phosphate isomerase. Cultures initiated from diluted samples containing an estimated 1.0 or 0.5 parasite showed microscopically visible parasites after 21 days. Most of these cultures were characterized by only single enzyme forms.
Science: the Struggle for Survival, 1880 to 1994
Authors: Kohlstedt Sally Gregory
Published: October 2006

The first issue ofSciencewas published on 3 July 1880 as a result of collaboration between journalist John Michels and inventor Thomas A. Edison. Although Edison withdrew his support after 18 months, Michels published three more issues and continued to seek support elsewhere. Earlier, Alexander Graham Bell expressed interest in the journal, but did not complete negotiations with Michels until after publication ofSciencehad ceased in 1882. In February 1883 the first issue of another series ofScienceappeared, this time supported by Bell and his father-in-law, Gardiner G. Hubbard. Publication then continued, under the editorship of Samuel H. Scudder and, subsequently, N. D. C. Hodges, until 1894, when, after an interval of several months,Sciencebecame the property of James McKeen Cattell.
Lethal Disruption of the Yeast Actin Gene by Integrative DNA Transformation
Authors: Shortle David , Haber James E. , Botstein David
Published: October 2006

A mutant allele of the chromosomal locus corresponding to the cloned actin gene of the yeast
Saccharomyces cerevisiae
has been constructed by DNA transformation with a hybrid plasmid which integrates into, and thereby disrupts, the protein-encoding sequences of the gene. In a diploid strain of yeast, disruption of the actin gene on one chromosome results in a mutation that segregates as a recessive lethal tightly linked to a selectable genetic marker on the integrated plasmid. The actin gene, therefore, must encode an essential function for yeast cell growth.
Diving Depths and Energy Requirements of King Penguins
Authors: Kooyman G. L. , Davis R. W. , Croxall J. P. , Costa D. P.
Published: October 2006

During 4- to 8-day periods at sea, half of 2595 dives of three king penguins were more than 50 meters and two dives exceeded 240 meters. The at-sea metabolic rate, estimated from the turnover of tritiated water, was 2.8 times the standard metabolic rate and requires about 2.5 kilograms of squid per day. Ten percent or less of the dives may result in prey capture.
Light-Induced Modification of
Drosophila
Retinal Polypeptides in Vivo
Authors: Matsumoto Hiroyuki , O'Tousa Joseph E. , Pak William L.
Published: October 2006

The effect of light on the polypeptide map profile of the
Drosophila
eye preparation was examined by two-dimensional polyacrylamide gel electrophoresis. The results show (i) that illuminating the living fly reversibly changes the isoelectric points of three classes of polypeptides specific for the photoreceptor layer and (ii) that the
norpA
mutation, which prevents the generation of the receptor potential, blocks the modifications.
Lizards Infected with Malaria: Physiological and Behavioral Consequences
Authors: Schall Jos. , Bennett Albert F. , Putnam Robert W.
Published: October 2006

In northern California, western fence lizards,
Sceloporus occidentalis
, are frequently parasitized by
Plasmodium mexicanum
, which causes malaria. Animals with this naturally occurring malarial infection are anemic: immature erythrocytes in peripheral blood become abundant (1 to 30 percent), and blood hemoglobin concentration decreases 25 percent. Maximal oxygen consumption decreases 15 percent and aerobic scope drops 29 percent in infected lizards; both correlate with blood hemoglobin concentration. Running stamina, but not burst running speed, is reduced in malarious lizards. There is a hierarchical relation between infection with malaria and effects on hematology, physiological function, and behavioral capacity. The results suggest that malarial infection may have significant effects on the ecology of lizard hosts.
Evidence of High Natural Radiation Doses in Certain Mid-Water Oceanic Organisms
Authors: Cherry R. D. , Heyraud M.
Published: October 2006

Concentrations of the naturally occurring radioactive nuclide polonium-210 were determined in mid-water crustaceans and fish from depths to 1500 meters. Unusually high levels were found in certain categories of organisms, indicating that these organisms were exposed to a particularly high natural radiation dose. The results have implications in terms of possible radiation effects, as a baseline against which artificial radioactive nuclides can be compared, and as a potential technique for studying the feeding behavior of mid-water organisms.
Discrimination and Imitation of Facial Expression by Neonates
Authors: Field Tiffany M. , Woodson Robert , Greenberg Reena , Cohen Debra
Published: October 2006

Human neonates (average age, 36 hours) discriminated three facial expressions (happy, sad, and surprised) posed by a live model as evidenced by diminished visual fixation on each face over trials and renewed fixations to the presentation of a different face. The expressions posed by the model, unseen by the observer, were guessed at greater than chance accuracy simply by observing the face of the neonate, whose facial movements in the brow, eyes, and mouth regions provided evidence for imitation of the facial expressions.
Echolocation in Bats: The External Ear and Perception of the Vertical Positions of Targets
Authors: Lawrence B. D. , Simmons J. A.
Published: October 2006

Echolocating bats (
Eptesicus fuscus
) can perceive changes of as little as 3° of arc in the vertical angles separating pairs of horizontal rods. This acuity depends upon modification of sounds entering the external ear canal by the structures of the external ear. Deflection of the tragus degrades the acuity of vertical-angle perception from 3° to about 12° to 14°. The pinna-tragus structure produces a strong secondary echo of sounds entering the external ear canal, and the delay of this echo after the time when the sound directly enters the ear canal apparently encodes the vertical direction of a sound source.
Topological Structure in Visual Perception
Authors: Chen L.
Published: October 2006

Three experiments on tachistoscopic perception of visual stimuli demonstrate that the visual system is sensitive to global topological properties. The results indicate that extraction of global topological properties is a basic factor in perceptual organization.
Human Fetal Movement: Spontaneous Oscillations Near One Cycle per Minute
Authors: Robertson Steven S. , Dierker LeRoy J. , Sorokin Yoram , Rosen Mortimer G.
Published: October 2006

Spectral analysis of spontaneous fluctuations in human fetal movement revealed strong oscillations at frequencies between 0.24 and 0.90 cycle per minute, which are much higher than those of the cyclic alternation of quiet and active states in the fetus and neonate. Oscillations at frequencies up to 2.88 cycles per minute were also detected, but they were usually much weaker. The prominent peaks in the fetal movement spectra are in the frequency range of recently reported neonatal motor rhythms, and indicate the existence of a cyclic process controlling spontaneous motor output that oscillates near one cycle per minute and begins to function in utero.
Survival and Differentiation of Identified Embryonic Neurons in the Absence of Their Target Muscles
Authors: Whitington Paul M. , Bate Michael , Seifert Eveline , Ridge Kimberley , Goodman Corey S.
Published: October 2006

Although prevented from contacting their target muscles, identified limb-innervating neurons in grasshopper embryos survive and differentiate to maturity.
Somatomedin C: Restoration in Vivo of Cycle Traverse in G
0
/G
1
Blocked Cells of Hypophysectomized Animals
Authors: Rothstein Howard , Van Wyk Judson J. , Hayden John H. , Gordon Sheldon R. , Weinsieder Allan
Published: October 2006

DNA synthesis and mitosis in frog lens epithelium are abolished by hypophysectomy and restored by somatomedin C. Both growth hormone and triiodothyronine also restore lens cell proliferation in vivo but not in vitro. Somatomedin-like activity in frog serum is diminished by hypophysectomy and is restored by growth hormone and triiodothyronine.
Mouse Oocytes Transcribe Injected
Xenopus
5
S
RNA Gene
Authors: Brinster Ralph L. , Chen Howard Y. , Trumbauer Myrna E.
Published: October 2006

Transcripts produced after injection of the
Xenopus
5
S
RNA gene into oocyte germinal vesicles of mice migrate electrophoretically with the 5
S
RNA marker, an indication that the gene is transcribed and processed with considerable accuracy. Approximately two 5
S
RNA molecules are transcribed per gene per hour. This system may be useful in studying DNA processing and gene regulation by the mammalian ovum and might be modified to allow permanent incorporation of specific genes into mice.
Opioid-Like Analgesia in Defeated Mice
Authors: Miczek Klaus A. , Thompson Michael L. , Shuster Louis
Published: October 2006

Mice exposed to repeated attacks by other mice showed decreased nociception in response to radiant heat focused on their tails. This form of analgesia was blocked by centrally acting opiate antagonists and was not observed in morphine-tolerant mice; furthermore, mice repeatedly subjected to defeat showed much less analgesia after receiving morphine than mice that were not subjected to defeat. Mice of the CXBK strain, which respond weakly to morphine, displayed only moderate analgesia following defeat. These findings suggest that endogenous opioid-mediated analgesic mechanisms are readily activated by situations involving biologically significant forms of stress, such as defeat.
Inherited Primary Hypothyroidism in Mice
Authors: Beamer Wesley G. , Eicher Eva M. , Maltais Lois J. , Southard Janice L.
Published: October 2006

A new autosomal recessive mutation that causes hypothyroidism has been identified in mice. The gene, herein named hypothyroid (
hyt
), has been mapped on chromosome 12 approximately 30 units from the centromere. The mutants are characterized by retarded growth, infertility, mild anemia, elevated serum cholesterol, very low to undetectable serum thyroxine, and elevated serum thyroid-stimulating hormone. Thyroid glands are in the normal location but are reduced in size and hypoplastic. Mutant mice respond to thyroid hormone therapy by improved growth and fertility. These findings suggest that the
hyt
mutant gene results in primary hypothyroidism unresponsive to thyroid-stimulating hormone.
Multiple Paternity in Belding's Ground Squirrel Litters
Authors: Hanken James , Sherman Paul W.
Published: October 2006

Sexually receptive female
Spermophilus beldingi
(Rodentia: Sciuridae) usually mate with several different males. The paternity of 27 litters born in 1977 and 1978 was ascertained by combining field observations of mating with laboratory paternity exclusion analyses. Most of the litters (78 percent) were multiply sired, usually by two or three males. This may be the highest frequency of multiple paternity ever directly demonstrated in a natural population.
Long-Term Potentiation in the Hippocampal Slice: Evidence for Stimulated Secretion of Newly Synthesized Proteins
Authors: Duffy Charles , Teyler Timothy J. , Shashoua Victor E.
Published: October 2006

Long-term potentiation of the hippocampal slice preparation results in an increase in the incorporation of labeled valine into the proteins destined for secretion into the extracellular medium. Double-labeling methods established that the increased secretion of the labeled proteins was limited to the potentiated region of a slice; incorporation of labeled valine was increased in the hippocampus if potentiation was through the Schaffer collaterals and in the dentate if potentiation was through the perforant path. Controls for nonspecific stimulation showed no changes. There appears to be a link between long-term potentiation and the metabolic processes that lead to protein synthesis in the hippocampal slice system.
Phase Relationships Between Adjacent Simple Cells in the Visual Cortex
Authors: Pollen Daniel A. , Ronner Steven F.
Published: October 2006

Adjacent simple cells recorded and "isolated" simultaneously from the same microelectrode placement were usually tuned to the same orientation and spatial frequency. The responses of the members of these "spatial frequency pairs" to drifting sine-wave gratings were cross-correlated. Within the middle range of the spatial frequency selectivity curves, the responses of the paired cells differed in phase by approximately 90°. This phase relationship suggests that adjacent simple cells tuned to the same spatial frequency and orientation represent paired sine and cosine filters in terms of their processing of afferent spatial inputs and truncated sine and cosine filters in terms of the output of simple cells.
Tonic Immobility Produces Hyperalgesia and Antagonizes Morphine Analgesia
Authors: Mauk Michael D. , Olson Richard D. , LaHoste Gerald J. , Olson Gayle A.
Published: October 2006

Hyperalgesia was demonstrated during and immediately after termination of tonic immobility in the lizard
Anolis carolinensis
. Additionally, tonic immobility antagonized morphine-induced analgesia. In conjunction with other research, these data suggest that the response is accompanied by a reduced availability of serotonin, possibly at postsynaptic receptors of raphe neurons.
Discharge Patterns of Hindlimb Motoneurons During Normal Cat Locomotion
Authors: Hoffer J. A. , O'Donovan M. J. , Pratt C. A. , Loeb G. E.
Published: October 2006

Long-term recording from single lumbar motoneurons of intact cats revealed activation patterns fundamentally different from those seen in decerebrate preparations. In intact cats, motoneuron bursts showed marked rate modulation without initial doublets. Each unit's frequencygram generally resembled the envelope of the gross electromyogram simultaneously recorded from the corresponding muscle. Average and peak discharge rates increased for faster gaits. These findings suggest that, in cat locomotion, rate modulation is a more important contributor to force regulation than was previously thought.
Rapid Massive Assembly of Tight Junction Strands
Authors: Kachar Bechara , Pinto da Silva Pedro
Published: October 2006

Incubation at 37°C of excised rat prostate tissue results in massive proliferative assembly of new tight junction strands along the entire length of the lateral plasma membranes of the columnar epithelial cells. The new tight junction elements are assembled within 5 minutes and have an average length six times that of those present in the apical tight junction band. Massive assembly occurs in the presence of protein synthesis inhibitors (cycloheximide) or of metabolic uncouplers (dinitrophenol). Thus, proliferative assembly of tight junction strands involves molecular reorganization from a pool of preexisting, probably membrane-associated, components. The fascia occludens and some examples of experimentally induced tight junction proliferation may reflect the massive emergence of tight junction strands when tissue is subjected to diverse stressful conditions.
The Posterior Pituitary: Regulation of Anterior Pituitary Prolactin Secretion
Authors: Peters Luanne L. , Hoefer Michael T. , Ben-Jonathan Nira
Published: October 2006

Removal of the posterior pituitary from anesthetized male rats results in a prompt and significant increase in circulating prolactin that is reversed by the injection of dopamine. Posterior pituitary extracts, which contain high concentrations of endogenous dopamine, inhibit prolactin secretion from isolated anterior pituitary cells. This inhibition is prevented by incubation of the cells with the dopamine receptor antagonist (+)-butaclamol. The data show that posterior pituitary dopamine reaches the anterior pituitary via the short hypophysial portal vessels and participates in the regulation of prolactin secretion.
Integration of Visual and Infrared Information in Bimodal Neurons in the Rattlesnake Optic Tectum
Authors: Newman Eric A. , Hartline Peter H.
Published: October 2006

Bimodal neurons in the rattlesnake tectum, which receive sensory input from the retina and from the infrared-sensing pit organ, exhibit novel, highly nonlinear cross-modality interactions. Some units respond only to simultaneous bimodal stimulation. Others respond to only one of the two modalities, but show greatly enhanced or depressed responses when stimulated simultaneously in the second modality. These cross-modality interactions may play an important role in recognizing and orienting toward biologically important objects.
Quantitation of Sprouting of Dorsal Root Axons
Authors: Hulsebosch Claire E. , Coggeshall Richard E.
Published: October 2006

The axonal sprouting that occurs after denervation resulting from a spinal hemisection can be quantified. Rats were subjected to hemisection of the spinal cord at birth, and the myelinated and unmyelinated axons in dorsal roots three segments cranial and three segments caudal to the lesion were counted 1 month after surgery. The number of unmyelinated axons in the dorsal root on the side of the hemisection increased 22 percent for the roots one segment from the lesion and 13 percent for the roots two and three segments from the lesion.
Central Norepinephrine Metabolism During Alcohol Intoxication in Addicts and Healthy Volunteers
Authors: Borg Stefan , Kvande Hans , Sedvall Göran
Published: October 2006

The concentrations of the major norepinephrine metabolite, 3-methoxy-4-hydroxyphenylethylene glycol (MOPEG), in lumbar cerebrospinal fluid of alcoholic patients were markedly elevated during intoxication and successively declined during 1 and 3 weeks of abstinence. During intoxication the MOPEG concentration in cerebrospinal fluid showed a statistically significant correlation with the blood alcohol concentration. In healthy volunteers who received 80 grams of ethanol, the MOPEG concentration in cerebrospinal fluid increased significantly. Healthy subjects sampled during intoxication had significantly higher concentrations of MOPEG in the cerebrospinal fluid than did subjects sampled after the end of intoxication. The results indicate that alcohol administration markedly stimulates norepinephrine metabolism in the central nervous system in human subjects possibly by increasing unit impulse activity of central noradrenergic neurons.
Staining of Blue-Sensitive Cones of the Macaque Retina by a Fluorescent Dye
Authors: de Monasterio F. M. , Schein S. J. , McCrane E. P.
Published: October 2006

Intravitreal injection of a fluorescent dye, Procion yellow, results in the complete and systematic staining of a cone population in the monkey retina. These cones form an approximately regular array whose separation varies with retinal eccentricity. They are absent in the very center of the fovea, and their density peaks at 1°. The distribution of stained cones resembles that reported for blue-sensitive cones of other primates and, consistent with such an identification, they are found with less incidence in species having lower concentrations of blue cones.
Role of Mediodorsal Thalamic Nucleus in Olfactory Discrimination Learning in Rats
Authors: Slotnick Burton M. , Kaneko Naohiro
Published: October 2006

Severe deficits in the acquisition of an olfactory learning-set task resulted from lesions of the central (olfactory) component of the mediodorsal thalamic nucleus but not from large lesions that destroyed olfactory projections to the amygdala. Complex olfactory learning may be mediated by the olfactory thalamocortical system and not by olfactory projections to the limbic system.
Spinal Motoneuron Recruitment in Man: Rank Deordering with Direction But Not with Speed of Voluntary Movement
Authors: Desnedt John E. , Gidaux E.
Published: October 2006

Single motor units in human interosseous muscle are recruited in order from small to large in slow or brisk voluntary abduction of the index finger. When the same muscle acts as a synergist as opposed to a prime mover, about 8 percent of the unit pairs consistently reversed their recruitment order. Motor commands appear to be patterned in terms of movements rather than muscles and to involve different connectivities to the motoneuron pool of a muscle executing movements in different directions.
The Stroop Effect: Brain Potentials Localize the Source of Interference
Authors: Duncan-Johnson Connie C. , Kopell Bert S.
Published: October 2006

The P300 component of the event-related brain potential was used in conjunction with reaction time to identify the locus of interference on the Stroop color-word test. Whereas response time varied with the congruence between the stimulus word and the color in which it was printed, the duration of stimulus processing, as indexed by P300 latency, remained constant. The results indicate that response competition is the primary source of Stroop interference.
The World Food Situation and Global Grain Prospects
Authors: Barr Terry N.
Published: October 2006

The basic realities of the distribution of the world's population, wealth, and agricultural production base are not conducive to an automatic stabilizing process for the world's hungry. Increasing volatility in world grain production in the 1980's could create a problem of major proportions. By 1990, the developed world will account for 24 percent of the world's population, 85 percent of the world's economic activity, and around 50 percent of the world's grain production and consumption. On a per capita basis, the developed world will consume nearly three times as much grain as the developing countries which account for three-fourths of the world's population. Increased food aid, which is essential, is not the solution to the basic problem. The low-income countries need a massive infusion of capital investment, research support, and education if they are to build infrastructures that have the capacity to produce, distribute, and market food supplies. Other options serve only to prolong and aggravate the current disparities.
Nursing Frequency, Gonadal Function, and Birth Spacing Among !Kung Hunter-Gatherers
Authors: Konner Melvin , Worthman Carol
Published: October 2006

Mothers among !Kung hunter-gatherers nurse briefly and frequently, with brief intervals between nursing bouts (mean ± standard error, 13.19 ± 1.28 minutes). The low levels of 17β-estradiol and progesterone in the serum of the mother are correlated with infant's age and with interbout interval, but not with total nursing time. Maternal gonadal function is apparently suppressed by a timing-dependent, prolactin-mediated effect of breast stimulation. Interbout interval may be a key variable in lactation infertility. If so, it solves the puzzle of !Kung birth spacing.
Allele Increasing Susceptibility to Human Breast Cancer May Be Linked to the Glutamate-Pyruvate Transaminase Locus
Authors: King Mary-Claire , Go Rodney C. P. , Elston Robert C. , Lynch Henry T. , Petrakis Nicholas L.
Published: October 2006

The patterns of the occurrence of breast cancer in 11 high-risk families were evaluated by segregation and linkage analysis. These patterns were consistent with the hypothesis that increased susceptibility to breast cancer was inherited as an autosomal dominant allele with high penetrance in women. The postulated susceptibility allele in these families may be chromosomally linked to the glutamate-pyruvate transaminase (E.C. 2.6.1.2, alanine aminotransferase) locus. Confirmation of this linkage in other families would establish the existence of a gene increasing susceptibility to breast cancer. Since there is no association in the general population between a woman's glutamate-pyruvate transaminase genotype and her cancer risk, the glutamate-pyruvate transaminase linkage cannot be used as a screening test for breast cancer.
Age-Related Changes in Passive Avoidance Retention: Modulation with Dietary Choline
Authors: Bartus Raymond T. , Dean Reginald L. , Goas J. Allen , Lippa Arnold S.
Published: October 2006

Two studies were performed to evaluate the effects of dietary choline manipulation on behavior in mice. Retired breeder mice (8.5 months old) were placed on purified diets that were either deficient in free choline or choline-enriched. After 4.5 months, the mice were trained in a single-trial, passive avoidance task and tested for retention either 24 hours or 5 days later. Their performance was compared with that of mice, of various ages, that were maintained on a control diet. The two salient findings were (i) a dramatic decrease in retention of the task in senescent mice (23 months and older) and (ii) marked behavioral differences between choline-deficient and choline-enriched mice (13 months old). In fact, the choline-enriched mice performed as well as 3-month-old mice, whereas the choline-deficient mice performed as poorly as the senescent mice. In a replication, three groups of retired breeder mice were placed on the same choline-deficient diet; control and enriched groups were given choline through their drinking water. Again, retention of learning was superior in the choline-enriched mice and inferior in the choline-deficient mice. These studies demonstrate that dietary manipulation of choline can significantly alter behavior in ways that are qualitatively and quantitatively similar to those occurring across the life-span of the mouse. Thus certain behavioral changes that occur with age might be modulated through appropriate precursor control.
Specific Antibodies: A Potential Insecticide
Authors: Nogge G. , Giannetti M.
Published: October 2006

When tsetse flies are fed on human blood, the hemolymph of the flies contains human albumin. If the flies then ingest antibodies to human albumin, they die within a short time. The albumin fraction in their hemolymph disappears and osmoregulation is severely disturbed.
Estimating Cancer Risks from Low Doses of Ionizing Radiation
Authors: Land Charles E.
Published: October 2006

Disagreements about the somatic risks from low doses of ionizing radiation stem from two difficulties fundamental to the logic of inference from observational data. First, precise direct estimation of small risks requires impracticably large samples. Second, precise estimates of low-dose risks based largely on high-dose data, for which the sample size requirements are more easily satisfied, must depend heavily on assumptions about the shape of the dose-response curve, even when only a few of the parameters of the theoretical form of the curve are unknown.
Brain Events Underlying Detection and Recognition of Weak Sensory Signals
Authors: Parasuraman Raja , Beatty Jackson
Published: October 2006

Through the use of a quantitative extension of signal detection theory, the brain events associated with the detection and recognition of weak acoustic signals were examined by recording brain event-related potentials. The early N100 component of the event-related potential varied only with detection, whereas the late P300 component varied with both detection and recognition. P300 amplitude accurately predicted recognition performance on a trial-by-trial basis. The results suggest that detection and recognition are partially concurrent processes in perception and demonstrate that the electrocortical events occurring during the perception of sensory stimuli are closely associated with both detection and recognition of these stimuli by the nervous system.
Direct Measurement of Microvascular Pressures in the Isolated Perfused Dog Lung
Authors: Bhattacharya J. , Staub N. C.
Published: October 2006

Microvascular pressures in the pulmonary circulation were measured under the pleural surface of the isolated perfused dog lung by the servo-null technique. Strong glass micropipettes with short beveled tips were used, with a suction ring to stabilize the lung's surface. Of the total vascular resistance, 45 percent was in the alveolar wall capillaries themselves. Most of the remaining resistance was in the arterioles. There was negligible pressure drop in venules with diameters larger than 20 micrometers.
Medial Nucleus of the Amygdala Mediates Chemosensory Control of Male Hamster Sexual Behavior
Authors: Lehman Michael N. , Winans Sarah S. , Powers J. Bradley
Published: October 2006

Bilateral lesions restricted to the medial nucleus of the amygdala eliminate mating behavior in the male hamster and severely diminish the male's sniffing and licking investigation of the female hamster's anogenital region. The results suggest that olfactory and vomeronasal sensory information critical to male mating behavior is processed in the medial nucleus, which is an androgen-binding brain area. Thus the medial nucleus may act as a relay through which chemosensory information influences activity in the medial preoptic-anterior hypothalamic junction and the bed nucleus of the stria terminalis, areas important in the mediation of male sexual behavior.
Thermoregulation in Doves (Columbidae): A Novel Esophageal Heat Exchanger
Authors: Gaunt Sandra L. L.
Published: October 2006

Key elements in avian thermoregulation at high temperatures are panting and gular flutter. Although these mechanisms are important, they are not sufficient to maintain body temperature below high ambient temperatures in doves. In the Columbidae, evaporative cooling from an inflated esophagus, driven by heat from a vascular plexus, is also essential.
Nerve Terminals Are as Metabolically Different as the Muscle Fibers They Innervate
Authors: Pickett Jackson B.
Published: October 2006

The rate at which glucose enters nerve terminals in muscle was estimated indirectly by measuring changes in miniature end-plate potential frequency. D-Glucose entered nerve terminals in muscles with a fast twitch more rapidly than it entered those with a slow twitch. This suggests that nerve terminals in fast- and slow-twitch muscles differ in their rate of metabolism.
Perception of Numbers by Human Infants
Authors: Starkey Prentice , Cooper Robert G.
Published: October 2006

Infants are capable of discriminating, representing, and remembering particular small numbers of items. A perceptual enumeration process called subitizing, present in 2-year-olds, probably underlies this capacity. This finding indicates that some number capacity is present before the onset of verbal counting, and it suggests that verbal counting may have precursors present during infancy.
Neurochemical and Behavioral Evidence for a Selective Presynaptic Dopamine Receptor Agonist
Authors: Goodale David B. , Rusterholz David B. , Long John P. , Flynn Jan R. , Walsh Brian , Cannon Joseph G. , Lee Teresa
Published: October 2006

A new dopamine analog, 6,7-dihydroxy-2-dimethylaminotetralin (TL-99), was compared to apomorphine in three tests of dopaminergic function in the central nervous system. The tests, performed on rats, included production of changes in locomotor activity (involving both presynaptic and postsynaptic receptors), inhibition of dopa accumulation (quantifying presynaptic receptor activity), and the rotation model (quantifying postsynaptic receptor activation). Apomorphine was efficacious at both presynaptic and postsynaptic receptors, whereas TL-99 was much more efficacious at the presynaptic receptor. This result indicates not only that differences exist between presynaptic and postsynaptic dopamine receptors, but also that these differences may be exploited in the design of selective dopamine agonists.
Type III Hyperlipoproteinemia: Defective Metabolism of an Abnormal Apolipoprotein E
Authors: Gregg Richard E. , Zech Loren A. , Schaefer Ernst J. , Brewer H. Bryan
Published: October 2006

The apolipoprotein E isolated from plasma of individuals with type III hyperlipoproteinemia (HLP) shows an abnormal pattern when it is examined by isoelectric focusing. Compared to apolipoprotein E from normal subjects, apolipoprotein E isolated from subjects with type III HLP had a decreased fractional catabolic rate in vivo in both type III HLP patients and normal individuals. The delayed catabolism of apolipoprotein E in type III HLP patients may be responsible for the lipid and lipoprotein abnormalities characteristic of these patients.
Grant Length and Budget Stability at the National Institutes of Health
Authors: Kalberer John T.
Published: October 2006

Decreasing the length of grant awards for biomedical research has been suggested as a means of ensuring greater accountability. An analysis of grant programs of the National Institutes of Health and, in particular, at the National Cancer Institute, revealed that the length recommended for grants is closely related to their perceived scientific merit. A principal conclusion is that selectively increasing the length of grants for only the most outstanding applications competing for renewal might improve research productivity while reducing research costs and easing the growing burden on the peer review process.
The Directed Mutation Controversy and Neo-Darwinism
Authors: Lenski Richard E. , Mittler John E.
Published: October 2006

According to neo-Darwinian theory, random mutation produces genetic differences among organisms whereas natural selection tends to increase the frequency of advantageous alleles. However, several recent papers claim that certain mutations in bacteria and yeast occur at much higher rates specifically when the mutant phenotypes are advantageous. Various molecular models have been proposed that might explain these directed mutations, but the models have not been confirmed. Critics contend that studies purporting to demonstrate directed mutation lack certain controls and fail to account adequately for population dynamics. Further experiments that address these criticisms do not support the existence of directed mutations.
Phosphorodithioate DNA as a Potential Therapeutic Drug
Authors: Marshall W. S. , Caruthers M. H.
Published: October 2006

This article summarizes methods for the synthesis of phosphorodithioate-linked deoxyoligonucleotides and details an analysis of one of the distinctive properties of phosphorodithioate DNA oligomers, their ability to strongly inhibit human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT). Mechanistic studies indicate that oligomers of this type interfere with enzyme function by binding tightly to the active site for primer-template, which results in low or subnanomolar inhibitory constants. Although many of these studies have used deoxyoligocytidine analogs, a rationally designed approach has led to the discovery of a very active phosphorodithioate deoxyoligonucleotide inhibitor. This type of inhibitor, which binds strongly to the primer-template active site of HIV-1 RT, provides another type of potential therapeutic agent against HIV-1.
Structure-Specific Endonucleolytic Cleavage of Nucleic Acids by Eubacterial DNA Polymerases
Authors: Lyamichev Victor , Brow Mary Ann D , Dahlberg James E.
Published: October 2006

Previously known 5′ exonucleases of several eubacterial DNA polymerases have now been shown to be structure-specific endonucleases that cleave single-stranded DNA or RNA at the bifurcated end of a base-paired duplex. Cleavage was not coupled to synthesis, although primers accelerated the rate of cleavage considerably. The enzyme appeared to gain access to the cleavage site by moving from the free end of a 5′ extension to the bifurcation of the duplex, where cleavage took place. Single-stranded 5′ arms up to 200 nucleotides long were cleaved from such a duplex. Essentially any linear single-stranded nucleic acid can be targeted for specific cleavage by the 5′ nuclease of DNA polymerase through hybridization with an oligonucleotide that converts the desired cleavage site into a substrate.
Systemic Gene Expression After Intravenous DNA Delivery into Adult Mice
Authors: Zhu Ning , Liggitt Denny , Liu Yong , Debs Robert
Published: October 2006

Direct gene transfer into adult animals resulting in generalized or tissue-specific expression would facilitate rapid analysis of transgene effects and allow precise in vivo manipulation of biologic processes at the molecular level. A single intravenous injection of expression plasmid:cationic liposome complexes into adult mice efficiently transfected virtually all tissues. In addition to vascular endothelial cells, most of the extravascular parenchymal cells present in many tissues including the lung, spleen, lymph nodes, and bone marrow expressed the transgene without any apparent treatment-related toxicity. The transgene was still expressed in large numbers of cells in multiple tissues for at least 9 weeks after a single injection. Expression could be targeted to specific tissues and cell types, depending on the promoter element used.
Calcium-Dependent Heparin-Like Ligands For L-Selectin in Nonlymphoid Endothelial Cells
Authors: Norgard-Sumnicht Karin E. , Varki Nissi M. , Varki Ajit
Published: October 2006

L-Selectin is a calcium-dependent mammalian lectin that mediates lymphocyte trafficking by recognizing sialylated ligands on high endothelial venules in lymph nodes. Although L-selectin probably mediates neutrophil extravasation into nonlymphoid tissues, no corresponding ligand has been characterized. Staining of cultured endothelial cells with an L-selectin chimera (LS-Rg) showed an internal pool of ligands. Metabolic labeling with sulfur-35-labeled sulfate revealed heparin lyase-sensitive ligands that bound LS-Rg in a calcium-dependent, sialic acid-independent manner. A fraction of commercial heparin bound to LS-Rg and LS-Rg bound to heparin-agarose, both in a calcium-dependent manner. Thus, L-selectin recognizes endothelial heparin-like chains, which could be physiological ligands mediating leucocyte trafficking.
Human Babesiosis: Reservoir of Infection on Nantucket Island
Authors: Healy George R. , Speilman Andrew , Gleason Neva
Published: October 2006

Examination of blood films from six species of rodents and lagomorphs on Nantucket Island disclosed infections with
Babesia microti
in all of five
Microtus pennsylvanicus
(field mice) and 31 of 39
Peromyscus leucopus
(white-footed or deer mice). Six human cases of clinical babesiosis have recently been diagnosed on the island.
Cloning of B7-2: a CTLA-4 Counter-Receptor That Costimulates Human T Cell Proliferation
Authors: Freeman Gordon J. , Gribben John G. , Boussiotis Vassiliki A. , Ng Judy W. , Restivo Vincent A. , Lombard Lisa A. , Gray Gary S. , Nadler Lee M.
Published: October 2006

Although presentation of antigen to the T cell receptor is necessary for the initiation of an immune response, additional molecules expressed on antigen-presenting cells deliver essential costimulatory signals. T cell activation, in the absence of costimulation, results in T cell anergy. The B7-1 protein is a costimulator molecule that regulates interleukin-2 (IL-2) secretion by signaling through the pathway that uses CD28 and CTLA-4 (hereafter referred to as the CD28 pathway). We have cloned a counter-receptor of CD28 and CTLA-4, termed B7-2. Although only 26 percent identical to B7-1, B7-2 also costimulates IL-2 production and T cell proliferation. Unlike B7-1, B7-2 messenger RNA is constitutively expressed in unstimulated B cells. It is likely that B7-2 provides a critical early costimulatory signal determining if the T cell will contribute to an immune response or become anergic.