bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiac Catabolic Factors: The Degradation of Heart Valve Intercellular Matrix
Authors: Decker Robert S. , Dingle John T.
Published: October 2006

Cultures of porcine heart valves and aorta secrete a factor that stimulates the degradation of cartilage matrix in a fashion similar to that displayed by synovial catabolin. The heart valve factor also induces the release of chondroitin sulfate and hydroxyproline from isolated heart valve cultures. The present observations support the hypothesis that tissues producing catabolic factors (catabolins) may well be responsive to them and that these messengers may play a role in the cellular regulation of the degradation of intercellular macromolecules.
Formation of an Adenine-Thymine Photoadduct in the Deoxydinucleoside Monophosphate d(TpA) and in DNA
Authors: Bose Samarendra N. , Davies R. Jeremy H. , Sethi Satinder K. , McCloskey James A.
Published: October 2006

A photoadduct is formed between the adenine (A) and thymine (T) bases of the deoxydinucleoside monophosphate d(TpA) when it is irradiated at 254 nanometers in aqueous solution. Treatment of the photoadduct with acid converts it specifically into a fluorescent hydrolysis product, C
7
H
7
N
3
O, incorporating the position-8 carbon of adenine and the methyl group of thymine. Isolation of the fluorescent hydrolysis product from acid hydrolyzates of oligo- and polydeoxyribonucleotides has shown that the photoadduct is formed by ultraviolet irradiation of d(pTpA), d(TpApT), d(TpApTpA), poly(dA-dT), and both single- and double-stranded DNA.
Heinz-Body Hemolytic Anemia from the Ingestion of Crude Oil: A Primary Toxic Effect in Marine Birds
Authors: Leighton Frederick A. , Peakall David B. , Butler Ronald G.
Published: October 2006

Hemolytic anemia developed in young herring gulls and Atlantic puffins given daily oral doses of a Prudhoe Bay crude oil. Anemia developed 4 to 5 days after the initiation of oil ingestion and was accompanied by Heinz-body formation and a strong regenerative response. The data evince a toxic effect on circulating red blood cells involving an oxidative biochemical mechanism and the first clear evidence of a primary mechanism of toxicity from the ingestion of crude oil by birds.
Erectile Mechanisms in Man
Authors: Karacan Ismet , Aslan Cengiz , Hirshkowitz Max
Published: October 2006

Increases in penile circumference during sleep-related erections in human subjects closely reflected increases in penile blood flow, and bursts of activity in the bulbocavernosus and ischiocavernosus muscles were temporally related to these increases. The penile arterial system and the perineal muscles appear to have important coordinated roles in human penile erection. Monitoring sleep-related erections and penile blood flow holds promise for the study of erectile mechanisms and dysfunction and for screening of drugs.
Consequences of Spatial Sampling by a Human Photoreceptor Mosaic
Authors: Williams David R. , Collier Robert
Published: October 2006

The short wavelength color mechanism in the human visual system can distinguish gratings from uniform fields of the same average radiance at spatial frequencies that are twice as high as the highest at which it can resolve bars in the grating. This discrimination above the resolution limit is associated with a splotchy or mottled appearance of the grating similar to two-dimensional noise. The most plausible explanation for the mottled pattern is that it is a moire pattern produced by aliasing (spatial undersampling) by an irregular and sparse mosaic of short wavelength cones.
Bloom's Syndrome: Evidence for an Increased Mutation Frequency in Vivo
Authors: Vijayalaxmi  , Evans H. J. , Ray J. H. , German J.
Published: October 2006

The incidence of lymphocytes resistant to the purine analog 6-thioguanine was studied in seven patients with Bloom's syndrome. The mean frequency was 17.3 × 10
-4
. The mean incidence in age- and sex-matched controls was 2.1 × 10
-4
, so approximately eight times the normal number of 6-thioguanine-resistant lymphocytes were detected in Bloom's syndrome blood. The basis for this increase is unknown, but the inherent genomic instability demonstrated in the form of chromosomal aberrations is one possible explanation.
Nucleosome Arcs and Helices
Authors: Dubochet Jacques , Noll Markus
Published: October 2006

Crystals and other regular arrangements of nucleosome cores have been obtained and analyzed in the electron microscope. Two types of regular structures have been studied in detail, the nucleosome arcs and cylinders. The latter are composed of concentric cylindrical layers of intertwined right-handed helices of nucleosome cores. These studies lead to the following conclusions and concepts. The overall structure of the nucleosome core is a short, wedge-shaped cylinder measuring about 110 by 110 by 60 angstroms. Nucleosome cores interact primarily between top and bottom planes. Nucleosome cores exhibit large conformational variability. A pivot allowing two degrees of rotational freedom is postulated in the region of the 70th base pair to account for this property of the nucleosome.
Calcium-Dependent Prolonged Effects on Melanophores of [4-Norleucine, 7-D-Phenylalanine]-α-Melanotropin
Authors: Hadley Mac E. , Anderson Britt , Heward Christopher B. , Sawyer Tomi K. , Hruby Victor J.
Published: October 2006

A single injection of the melanotropin analog [4-norleucine, 7-D-phenylalanine]-α-melanotropin into frogs (
Rana pipiens
) caused near maximum darkening of the skins of the frogs for at least 6 weeks. Injections of the natural hormone α-melanotropin or of the analog [Nle
4
]-α-melanotropin also caused darkening, but this effect lasted only a few days. Morphological examination of the skins of frogs injected with [Nle
4
, D-Phe
7
]-α-melanotropin revealed that both dermal and epidermal melanophores were dispersed during the entire 6-week period. In vitro [Nle
4
, D-Phe
7
]-α-melanotropin also causes prolonged darkening of the skin of the lizard
Anolis carolinensis
. In the absence of the melanotropin, skins previously darkened with the analog could be lightened by removal of calcium from the incubation medium but could then be redarkened by adding calcium. The cycle could be repeated indefinitely without addition of melanotropin. These results demonstrate the role of calcium in receptor signal transduction and the prolonged biological effects of [Nle
4
, D-Phe
7
]-α-melanotropin long after its removal from the assay medium.
The Fourth Pacific Science Congress
Authors: Vaughan T. Wayland
Published: October 2006

Java was hot and there were other discomforts, but all who were present at the congress returned to their homes appreciative of the charms and manifold subjects of scientific and other kinds of interest of what is perhaps the most fascinating of tropical islands, deeply grateful for the courtesies and hospitality extended to them and convinced that the Fourth Pacific Science Congress was the most successful of that series of congresses. Thanks are due all of those who contributed to the social enjoyment and the scientific accomplishments of the congress, but it may be permissible to emphasize the part played by the general president, Dr. Otto de Vries. He showed capacity in the organization of the congress, his handling of all matters connected with it was tactful and his genial personality endeared him to every one. We congratulated him on his success and told him that we were proud of him.
Bioactive Conformation of Luteinizing Hormone-Releasing Hormone: Evidence from a Conformationally Constrained Analog
Authors: Freidinger Roger M. , Veber Daniel F. , Perlow Debra Schwenk , Brooks Jerry R. , Saperstein Richard
Published: October 2006

An analog of luteinizing hormone-releasing hormone containing a γ-lactam as a conformational constraint has been prepared with the use of a novel cyclization of a methionine sulfonium salt. The analog is more active as a luteinizing hormone-releasing hormone agonist than the parent hormone, and provides evidence for a bioactive conformation containing a β-turn.
Male Vole Urine Changes Luteinizing Hormone-Releasing Hormone and Norepinephrine in Female Olfactory Bulb
Authors: Dluzen Dean E. , Ramirez Victor D. , Carter C. Sue , Getz Lowell L.
Published: October 2006

Female prairie voles (
Microtus ochrogaster
) exposed to a single drop of male urine on the upper lip showed changes in concentrations of luteinizing hormone-releasing hormone (LHRH) and norepinephrine in olfactory bulb tissue; no such changes occurred in dopamine concentration. The changes were measured in the posterior but not the anterior olfactory bulb tissue of females within 1 hour after they were exposed to urine. These females also showed rapid increases in serum concentrations of luteinizing hormone. Females exposed to water on the upper lip showed none of these changes. These results suggest that in this species LHRH and norepinephrine in the olfactory bulb may mediate luteinizing hormone release in response to external (pheromonal) chemical cues.
Novel Peptide Neuronal System in Rat Brain and Pituitary
Authors: Weber Eckard , Evans Christopher J. , Samuelsson Steven J. , Barchas Jack D.
Published: October 2006

Immunohistofluorescence studies of the rat central nervous system with antibodies to Phe-Met-Arg-Phe-NH
2
(molluskan cardioexcitatory peptide) revealed a widespread neuronal system in the brain, spinal cord, and posterior pituitary. Immunoreactive axons and cell bodies were mainly located in cortical, limbic, and hypothalamic areas. Immunostaining of serial sections of the brain and pituitary showed that the Phe-Met-Arg-Phe-NH2 immunoreactive neurons were different from neurons labeled by antibodies to either Met-enkephalin or the putative Met-enkephalin precursor Tyr-Gly-Gly-Phe-Met-Arg-Phe, which is structurally related to Phe-Met-Arg-Phe-NH
2
. Control staining by antiserum absorption and radioimmunoassay indicated that the antibodies that caused the specific immunofluorescence recognized peptides with an amidated Arg-Phe sequence at the carboxyl terminus.
Uninvolved Skin from Psoriatic Patients Develops Signs of Involved Psoriatic Skin After Being Grafted onto Nude Mice
Authors: Fraki Jorma E. , Briggaman Robert A. , Lazarus Gerald S.
Published: October 2006

Clinically involved psoriatic epidermis maintains its histological appearance, increased labeling index, and increased level of plasminogen activator after being grafted onto athymic nude mice. Uninvolved psoriatic epidermis develops increases in plasminogen activator activity after being grafted onto athymic nude mice; this is accompanied by an increased labeling index. Thus, psoriatic skin can develop markers of psoriasis independent of the host.
Atmospheric Reactions of Polycyclic Aromatic Hydrocarbons: Facile Formation of Mutagenic Nitro Derivatives
Authors: Pitts James N. , Van Cauwenberghe Karel A. , Grosjean Daniel , Schmid Joachim P. , Fitz Dennis R. , Belser William L. , Knudson Gregory B. , Hynds Paul M.
Published: October 2006

Directly active mutagens are formed on exposure of the promutagen benzo[
a
]pyrene to gaseous pollutants in smog. In simulated atmospheres containing 1 part per million nitrogen dioxide and traces of nitric acid, directly mutagenic nitro derivatives are readily formed from both benzo[
a
]pyrene and perylene, a nonmutagen in the Ames reversion assay. Possible formation of direct mutagens by such reactions on sample collection filters, in exhaust effluents, and in the atmosphere should be recognized.
Sedimentation Field Flow Fractionation of Liposomes
Authors: Kirkland J. J. , Yau W. W. , Szoka F. C.
Published: October 2006

Quantitative analyses of the particle size distributions of liposomes were performed in 30 to 60 minutes by exponential-field sedimentation field flow fractionation. This gentle new separation method exhibits great potential for the high-resolution fractionation and the size or molecular weight analysis of a wide variety of biological macromolecules and colloidal suspensions.
DNA Sequence of a Gene Encoding a BALB/c Mouse L
d
Transplantation Antigen
Authors: Moore Kevin W. , Sher Beverly Taylor , Sun Y. Henry , Eakle Kurt Andrew , Hood Leroy
Published: October 2006

The sequence of a gene, denoted 27.5, encoding a transplantation antigen for the BALB/c mouse has been determined. Gene transfer studies and comparison of the translated sequence with the partial amino acid sequence of the L
d
transplantation antigen establish that gene 27.5 encodes an L
d
polypeptide. A comparison of the gene 27.5 sequence with several complementary DNA sequences suggests that the BALB/c mouse may contain a number of closely related L-like genes. Gene 27.5 has eight exons that correlate with the structural domains of the transplantation antigen.
Splitting of the Circadian Rhythm of Activity Is Abolished by Unilateral Lesions of the Suprachiasmatic Nuclei
Authors: Pickard Gary E. , Turek Fred W.
Published: October 2006

The circadian rhythm of activity in vertebrates often splits into two components after continuous exposure to constant light. This observation suggests that at least two circadian pacemakers underlie the activity rhythm. After unilateral ablation of the hypothalamic suprachiasmatic nuclei in hamsters, the splitting phenomenon was eliminated and a single rhythm of activity was established. The period of the new circadian activity rhythm differed from the periods of the split rhythm and that preceding the split. These results suggest an interaction between the bilaterally paired suprachiasmatic nuclei in the generation of the circadian rhythm of activity.
Developmental Changes in the Biliary Excretion of Methylmercury and Glutathione
Authors: Ballatori Nazzareno , Clarkson Thomas W.
Published: October 2006

The long half-time for methylmercury in the neonatal rat is explained by the neonatal liver's inability to secrete the toxin into bile, which in adults is the main route of elimination. The ability to secrete mercury into bile develops between 2 and 4 weeks of age and is correlated with the increasing ability of the developing liver to secrete glutathione into bile.
Oxytocin Induces Maternal Behavior in Virgin Female Rats
Authors: Pedersen Cort A. , Ascher John A. , Monroe Yvonne L. , Prange Arthur J.
Published: October 2006

Intracerebroventricular administration of oxytocin to virgin female rats that had been ovariectomized and primed with estrogen 48 hours previously induced a rapid onset of full maternal behavior. The maternal behavior persisted and its incidence was dose-related. Tocinoic acid, the ring structure of oxytocin, also rapidly induced the onset of persistent, full maternal behavior. Arginine vasopressin induced persistent maternal behavior, but this behavior had a later onset. Prostaglandin F
2α
induced strong partial maternal behavior, which showed early onset but did not persist. Many other peptides, ovarian steroids, and prostaglandin E
2
were no more effective than saline. These findings suggest that the release of oxytocin and prostaglandin F
2α
during labor may promote maternal behavior in rats.
Modulation of Striatal Dopaminergic Function by Local Injection of 5′-
N
-Ethylcarboxamide Adenosine
Authors: Green Richard D. , Proudfit Herbert K. , Yeung Siu-Mei H.
Published: October 2006

Rats rotated to the left when 5′-
N
-ethylcarboxamide adenosine (NECA) was injected into the left caudate nucleus and apomorphine was administered subcutaneously. The combination of NECA and apomorphine was more potent than L-(phenylisopropyl)adenosine and apomorphine in eliciting rotation, suggesting the involvement of adenosine receptors of the R
a
type. The response was reduced when 2′,5′-dideoxyadenosine was injected along with NECA into the caudate nucleus or when theophylline was given intraperitoneally. Higher doses of apomorphine elicited a self-mutilatory response after the injection of NECA into the caudate nucleus. These results suggest that adenosine may be involved in the modulation of dopaminergic function in the striatum.
Double Minute Chromosomes and the Homogeneously Staining Regions in Chromosomes of a Human Neuroblastoma Cell Line
Authors: Balaban-Malenbaum Gloria , Gilbert Fred
Published: October 2006

Four human neuroblastoma cell lines were studied by chromosome banding techniques. All of the lines contained a marker chromosome with a long nonbanding homogeneously staining region (HSR). The HSR-containing chromosome differed in each line. One line contained two classes of cells: one with an HSR marker chromosome and the other with double minute chromosomes. Each cell had one of these abnormalities; no cell had both. The presence of two additional chromosomal markers in all cells of this line indicates a common origin. These observations suggest that the double minute chromosomes are derived from the HSR.
Tumor Shedding and Coagulation
Authors: Dvorak H. F. , Quay S. C. , Orenstein N. S. , Dvorak A. M. , Hahn P. , Bitzer A. M. , Carvalho A. C.
Published: October 2006

Three syngeneic carcinomas from two species shed plasma membrane vesicles when cultured in vitro or grown in the ascites tumor form in vivo. Shed vesicles carry procoagulant activity that can account for the activation of the clotting system and the fibrin deposition associated with these and many other types of malignancy in animals and man.
Organic Fluorine in Human Serum: Natural Versus Industrial Sources
Authors: Belisle Jon
Published: October 2006

The concentration of organic fluorine in human serum has been reported to vary from 0.0 to 0.13 part per million in persons not exposed to industrial fluorochemicals. To help ascertain whether the natural environment is a source of organic fluorine in human serum, samples from a group of rural Chinese were analyzed. The samples contained low levels of organic fluorine as well as the expected inorganic fluoride.
Brain Acetylcholine Synthesis Declines with Senescence
Authors: Gibson Gary E. , Peterson Christine , Jenden Donald J.
Published: October 2006

The synthesis of whole brain acetylcholine is reduced in two strains (C57BL and BALB/c) of senescent mice. The incorporation of [U-
14
C]glucose into acetylcholine decreased in both strains by 40 ± 4 percent in 10-month-old mice and by 58 ± 9 percent in 30-month-old mice compared with mice 3 months old. The incorporation of [
2
H
4
]choline into acetylcholine declined 60 and 73 percent in 10- and 30-month-old mice, respectively. Deficits in the cholinergic system may contribute to brain dysfunctions that complicate senescence.
Brown Adipose Tissue: Thermic Response Increased by a Single Low Protein, High Carbohydrate Meal
Authors: Glick Zvi , Teague Ralph J. , Bray George A.
Published: October 2006

The weight of interscapular brown fat in the rat and its rate of respiration increased in response to a single meal. These data suggest that brown adipose tissue plays a role in the thermic effect of meals and that diet-induced thermogenesis may reflect the summation of the thermic effects of single meals during prolonged overeating.
Retrograde Amnesia: Possible Role of Mesencephalic Reticular Activation in Long-Term Memory
Authors: Goldberg Elkhonon , Antin Sanford P. , Bilder Robert M. , Gerstman Louis J. , Hughes James E. O. , Mattis Steven
Published: October 2006

A patient with cerebral trauma recovered considerably from the resulting anterograde but not retrograde amnesia. The persistence of retrograde amnesia is attributed to a lesion in the ventral tegmental region, which suggests a role for mesencephalic reticular activation in long-term retrieval.
Fermentation in the Rumen and Human Large Intestine
Authors: Wolin Meyer J.
Published: October 2006

Fermentation of food by the microbial community of the rumen is essential for the maintenance and growth of ruminants. The microbial ecosystem and its interaction with the host are described, along with recent attempts to manipulate the composition and activity of the microbial community by adding antibiotics and other chemicals to ruminant diets. A similar microbial community and fermentation occur in the large intestine or cecum of most nonruminant animals including the large intestine of humans. The microbial ecosystems of the rumen and human large intestine are compared.
Instrumental Control of Cardioacceleration Induced by Central Electrical Stimulation
Authors: Joseph J. A. , Engel B. T.
Published: October 2006

Each of four monkeys (
Macaca mulatta
) was operantly conditioned to slow and to speed heart rate through a shock-avoidance procedure. During these sessions, electrical brain stimulation that produced tachycardia and pressor responses was delivered on alternate, 64-second segments to one of several brain regions. All animals were able to attenuate the increases in heart rate produced by brain stimulation during the slowing sessions when posterior hypothalamic and striatal regions were stimulated but not when anterior hypothalamic or subthalamic areas were stimulated. During speeding or control sessions during which heart rate was monitored, brain stimulation continued to increase heart rate.
Metallized Food in the Regeneration of Hemoglobin in Rat and Man
Authors: McGhee J. L.
Published: October 2006

(1) Metals dissolve enough in milk to supply the requirements for rapid regeneration of hemoglobin in rat and man.

(2) Copper alone is effective but less so than when accompanied by other metals, especially iron.

(2) Much less mortality occurs among rats fed on metallized milk than when salts of the metals are used in anemia tests.

(4) These metals produce no odor, color, taste or other observed change in milk with the quantities used unless they are exposed to air and milk.
Retroactive Interference in Discrimination Learning
Authors: Heinemann Eric G. , Sage-Day Julie , Brenner Neil
Published: October 2006

In stage 1 of this experiment pigeons were trained to discriminate between two levels of noise or two colors by pecking on one of two disks. In stage 2 the discriminative stimuli were not presented, but pecking on the disks was rewarded on a random schedule. The second procedure caused the pigeons to forget the discrimination they had learned.
Group-Specific Component: Evidence for two Subtypes of the Gc
1
Gene
Authors: Constans J. , Viau M.
Published: October 2006

A new method based on isofocusing electrophoresis in the study of the Gc (group-specific component) polymorphism, revealed differing electrophoretic patterns. These patterns can be explained by the existence of two codominant Gc
1
subtypes. This hypothesis is in accordance with several family studies. These subtypes are called Gc
1F
and Gc
1S
. Eight hundred samples were analyzed, including three different populations: Caucasoid (a western Pyrenean valley), African (Pygmy Bi-Aka), and Amerindian (Quechua-Aymara, from Bolivia). These two subtype phenotypes cannot be explored with the usual technique. They were present in each population sample studied.
Splanchnic Somatostatin: A Hormonal Regulator of Nutrient Homeostasis
Authors: Schusdziarra V. , Zyznar E. , Rouiller D. , Boden G. , Brown J. C. , Arimura A. , Unger R. H.
Published: October 2006

Free (∼ 1600 daltons) somatostatin-like immunoreactivity was identified in arterial plasma of dogs that had received a test meal. Neutralization of circulating somatostatin while the dogs were consuming a fatty meal increased the plasma concentrations of triglycerides, gastrin, pancreatic polypeptide, and insulin after the meal. It is concluded that, in the dog, somatostatin is a true hormone that regulates the movement of nutrients from the gut to the internal environment.
Food Dyes Impair Performance of Hyperactive Children on a Laboratory Learning Test
Authors: Swanson James M. , Kinsbourne Marcel
Published: October 2006

Forty children were given a diet free of artificial food dyes and other additives for 5 days. Twenty of the children had been classified as hyperactive by scores on the Conners Rating Scale and were reported to have favorable responses to stimulant medication. A diagnosis of hyperactivity had been rejected in the other 20 children. Oral challenges with large doses (100 or 150 milligrams) of a blend of FD & C approved food dyes or placebo were administered on days 4 and 5 of the experiment. The performance of the hyperactive children on paired-associate learning tests on the day they received the dye blend was impaired relative to their performance after they received the placebo, but the performance of the nonhyperactive group was not affected by the challenge with the food dye blend.
Photoluminescent Thermometer Probes: Temperature Measurements in Microwave Fields
Authors: Samulski Thaddeus , Shrivastava Prakash N.
Published: October 2006

Based on luminescence, the photoluminescent thermometer can in principle function in electromagnetic fields without field coupling and perturbation. Several prototypal probes that have been constructed and tested demonstrate the feasibility of the concept. Temperature resolution of approximately 0.3°C has thus far been achieved. The probes are needle-shaped, sturdy and less than 1 millimeter in size. This thermometer system has excellent potential application in monitoring and controlling tissue temperatures when microwaves are used to induce hyperthermia for cancer treatment.
An "Inhibitory" Influence on Brainstem Population Responses
Authors: Stanny R. R. , Elfner L. F.
Published: October 2006

Forward masking was used to obtain measurements of physiological masking and two-tone unmasking from short-latency evoked potentials and psychophysical responses in human subjects. The physiological results are in qualitative agreement with data on inhibitory phenomena in nonhuman auditory systems. The neural and behavioral data obtained thus far agree well.
Natural Products from Microorganisms
Authors: Woodruff H. Boyd
Published: October 2006

Microorganisms are capable of producing natural products with widely divergent chemical structures. Greatest attention in the past has been paid to natural products that have antibiotic properties. Natural products accumulate in fermentation broths during secondary metabolism, a characteristic of the incomplete metabolic control operative in growth-inhibited microorganisms. With this general mechanism of biosynthesis, the natural products synthesized by microorganisms would be expected to have a broad range of pharmacological activities. The directed screening for nonantibiotic natural products has been of limited scope. The expectation that new compounds of interest would be found has been validated. The pharmacologically active natural products provide previously unrecognized structures as tools for fundamental research programs, as well as offering the possibility of direct use in medicine or in industrial processes.
Sexual Dimorphism in Extent of Axonal Sprouting in Rat Hippocampus
Authors: Loy Rebekah , Milner Teresa A.
Published: October 2006

Sympathetic axons, normally innervating the extracerebral vasculature, sprout into denervated regions of the hippocampal formation after lesions of the medial septal nucleus or fimbria in adult female rats. Similar lesions in adult males also elicit the sympathetic ingrowth; however, the number of anomalous axons is greatly reduced and their distribution is altered. In adult males the sympathetic axons do not send out collaterals within the stratum oriens of region CA3 or the molecular layer or deep hilar regions of the area dentata, as they do in adult females. Lesions in juveniles of both sexes result in more vigorous sprouting than in their adult counterparts. In the young males the anomalous axons are distributed more extensively into the dentate molecular layer; in the young females the axons merely send out more collaterals within the same regions as in the adults. This sexually dimorphic response to central nervous system damage suggests either that the sprouting is affected by the hormonal environment of the mature hippocampal system or that this brain region, like the hypothalamus, may express permanent morphological or physiological differences as a result of exposure to sex steroids during development.
Cell-Free Synthesis of Acetylcholine Receptor Polypeptides
Authors: Mendez Bernadita , Valenzuela Pablo , Martial Joseph A. , Baxter John D.
Published: October 2006

Messenger RNA coding for acetylcholine receptor peptides has been identified. This polyadenylate [poly(A)
+
] RNA from
Torpedo californica
directs, in a cell-free system, the synthesis of peptides 60,000, 51,000, 49,000 41,000, and 35,000 daltons which account for approximately 2 percent of the total synthesized proteins. The results suggest that several different messenger RNA's code for the receptor subunits. These proteins react specifically to antiserum to native acteylcholine receptor, suggesting that the primary translational product has conformational features similar to the native receptor. Further, the results support the idea that there is post-translational modification of receptor subunits as the molecular weights of the cell-free synthesized proteins differ from those of purified receptor subunits.
Sodium-Induced Elevation of Blood Pressure in the Anephric State
Authors: Hatzinikolaou Peter , Gavras Haralambos , Brunner Hans R. , Gavras Irene
Published: October 2006

Normotensive anephric rats infused with 2 milliliters of a hyperosmolar solution of either sodium chloride or mannitol showed an increase in arterial pressure that was very pronounced with the sodium chloride and that could be partly abolished by administration of an antagonist to the vasopressor action of antidiuretic hormone (ADH). Rats with congenital ADH deficiency subjected to the same treatment showed smaller increments in arterial pressure that remained unchanged after administration of the ADH antagonist. Expansion of intravascular fluid volume was similar in all four groups and bore no correlation to the change in arterial pressure. It is concluded that about half of the increase in blood pressure induced by saline was attributable to the vasopressor effect of stimulated ADH and the remainder to an additional sodium-related factor, since it was more pronounced in the saline-infused than in the mannitol-infused groups. Expansion of the intravascular volume per se could only account for a minimal part of the increment in pressure.
Electrophoretic Injection of a Fluorescent Dye into Giant Mitochondria and Mitoplasts
Authors: Bowman Charles , Tedeschi Henry
Published: October 2006

Studies of the electrical properties of giant mitochondria and mitoplasts with microelectrodes have indicated that there are no significant metabolically dependent membrane potentials. The internal location of the microelectrode has been confirmed by electrophoretically microinjecting the water-soluble dye Lucifer yellow CH into giant mitochondria or mitoplasts.
Visualization of a Guinea Pig T Lymphocyte Surface Component Cross-Reactive with Immunoglobulin
Authors: Marchalonis John J. , Bucana Cora , Hoyer Larry , Warr Gregory W. , Hanna M. G. , Szenberg Alex
Published: October 2006

Thymus-derived lymphocytes (T cells) show exquisite specificity in recognition of antigens, but the nature of the cell surface receptor is controversial. Although antigen recognition mediated by immunoglobulin variable (V) regions remains the minimal hypothesis, it has been extremely difficult to definitely establish the presence of immunoglobulins on these cells. Chicken antibodies, produced against the (Fab′)
2
fragment of mouse immunoglobulin G (IgG) and purified by binding to and elution from IgG-Sepharose 4B, bind to an endogenously synthesized surface component of guinea pig T cells. The binding occurred via a cross-reaction with murine κ chain and a heavy chain determinant localized in the Fd region, and was visualized by immunofluorescence and immunoelectronmicroscopy using both transmission and scanning techniques. These data provide direct evidence for the presence of a surface component related to immunoglobulin on T lymphocytes.
Membrane Depolarization Accumulates During Acquisition of an Associative Behavioral Change
Authors: Alkon Daniel L.
Published: October 2006

Long-lasting electrical changes of identified
Hermissenda
neurons, the type B photoreceptors, can account for concomitant associative behavioral changes. Depolarization of the type B cells after paired light and rotation accumulates (as monitored with intracellular electrodes) with repetition. This accumulation was specific to stimulus pairing (versus light alone or explicitly unpaired stimuli) and to the orientation of the nervous system with respect to the center of rotation; it provides a neural step in the acquisition of associative behavioral changes for gastropod mollusks and possibly other species.
Osmolality and Potassium Ion: Their Roles in Initiation of Sperm Motility in Teleosts
Authors: Morisawa Masaaki , Suzuki Keiji
Published: October 2006

Spermatozoa that are quiescent in electrolyte and nonelectrolyte solutions isotonic to seminal plasma show motility when the semen is diluted with hypotonic solution in freshwater teleosts (four species tested) and with hypertonic solution in marine teleosts (five species tested). Decrease or increase, respectively, in osmolality of the environment may be the factor initiating sperm motility in these species. The motility of chum salmon spermatozoa in a sodium chloride solution isotonic to seminal plasma is completely suppressed by approximately 10 millimoles of potassium per kilogram; topminnow spermatozoa, however, were immotile in a nonelectrolyte solution, and motility was induced by electrolytes, especially potassium. Thus ions, rather than osmolality, may be an essential determinant of sperm motility in salmonid and viviparous teleosts.
Retinal Chromophore of Rhodopsin Photoisomerizes Within Picoseconds
Authors: Hayward Gary , Carlsen William , Siegman Anthony , Stryer Lubert
Published: October 2006

A new picosecond resonance Raman technique shows that resonance Raman lines characteristic of a distorted all-
trans
retinal appear within 30 picoseconds after photolysis of rhodopsin or isorhodopsin. This finding suggests that isomerization is nearly complete within picoseconds of the absorption of a photon.
Dye Transfer Through Gap Junctions Between Neuroendocrine Cells of Rat Hypothalamus
Authors: Andrew R. David , MacVicar Brian A. , Dudek F. Edward , Hatton Glenn I.
Published: October 2006

Most magnocellular neurosecretory cells that terminate in the posterior pituitary secrete either vasopressin, oxytocin, or enkephalin. Intracellular injection of the fluorescent dye Lucifer Yellow into single magnocellular neurons in slices of rat hypothalamus resulted in dye transfer between these cells. Freeze-fracture replicas of these cells occasionally revealed gap junctions, which presumably contain channels that mediate the dye coupling. These two independent techniques strongly suggest that some mammalian neuropeptidergic cells are electrotonically coupled, providing a possible means for recruitment and synchronization of their electrical activity.
Common Origin of Pigment Cells
Authors: Bagnara Joseph T. , Matsumoto Jiro , Ferris Wayne , Frost Sally K. , Turner William A. , Tchen T. T. , Taylor John D.
Published: October 2006

The fundamentally diverse vertebrate pigment cells, melanophores, xanthophores, and iridophores, contain pigmentary organelles known, respectively, as melanosomes, pterinosomes, and reflecting platelets. Their pigments are melanins, pteridines, and purines. Mosaic pigment cells containing more than one type of organelle have been observed and mosaic organelles containing more than one type of pigment have been discovered. It is proposed that the various pigment cells are derived from a stem cell that contains a primordial organelle of endoplasmic reticular origin. This primordial organelle can differentiate into any of the known pigmentary organelles.
Human Muscular Dystrophy: Elevation of Urinary Dimethylarginines
Authors: Lou Marjorie F.
Published: October 2006

The amounts of the dimethylarginines N
G
, N
G
-dimethylarginine (DMA) and N
G
, N′
G
-dimethylarginine (DM′A) excreted in the urine of muscular dystrophic patients were examined and compared with the amounts excreted by normal controls, patients with other types of neuromuscular diseases, and patients with disuse muscle atrophy resulting from traumatic paralysis. The patients with muscular dystrophy excreted high concentrations of DMA and this urine showed high ratios of DMA to DM'A. This finding indicates a relation between protein methylation processes and muscular dystrophy.
Multiple Output Channels in the Basal Ganglia
Authors: Hoover John E. , Strick Peter L.
Published: October 2006

The neural circuits that link the basal ganglia with the cerebral cortex are critically involved in the generation and control of voluntary movement. Retrograde transneuronal transport of herpes simplex virus type 1 was used to examine the organization of connections in the cebus monkey between an output nucleus of the basal ganglia, the internal segment of the globus pallidus (GPi), and three cortical areas: the primary motor cortex, the supplementary motor area, and the ventral premotor area. Spatially separate regions of the GPi were labeled after virus injections into each cortical area. The GPi projects to multiple cortical motor areas, and this pallidal output is organized into discrete channels. This information provides a new anatomical framework for examining the function of the basal ganglia in skeletomotor control.
Microbial Competition:
Escherichia coli
Mutants That Take Over Stationary Phase Cultures
Authors: Zambrano María Mercedes , Siegele Deborah A. , Almirón Marta , Tormo Antonio , Kolter Roberto
Published: October 2006

Many microorganisms, including
Escherichia coli
, can survive extended periods of starvation. The properties of cells that survived prolonged incubation in stationary phase were studied by mixture of 10-day-old (aged) cultures with 1-day-old (young) cultures of the same strain of
Escherichia coli
. Mutants from the aged cultures that could grow eventually took over the population, which resulted in the death of the cells from the young cultures. This phenotype was conferred by mutations in
rpoS
, which encodes a putative stationary phase-specific sigma factor. These rapid population shifts have implications for the studies of microbial evolution and ecology.
Controlling Signal Transduction with Synthetic Ligands
Authors: Spencer David M. , Wandless Thomas J. , Schreiber Stuart L. , Crabtree Gerald R.
Published: October 2006

Dimerization and oligomerization are general biological control mechanisms contributing to the activation of cell membrane receptors, transcription factors, vesicle fusion proteins, and other classes of intra- and extracellular proteins. Cell permeable, synthetic ligands were devised that can be used to control the intracellular oligomerization of specific proteins. To demonstrate their utility, these ligands were used to induce intracellular oligomerization of cell surface receptors that lacked their transmembrane and extracellular regions but contained intracellular signaling domains. Addition of these ligands to cells in culture resulted in signal transmission and specific target gene activation. Monomeric forms of the ligands blocked the pathway. This method of ligand-regulated activation and termination of signaling pathways has the potential to be applied wherever precise control of a signal transduction pathway is desired.
Requirement of Tyrosine Phosphorylation for Rapid Activation of a DNA Binding Factor by IL-4
Authors: Kotanides Helen , Reich Nancy C.
Published: October 2006

Interleukin-4 (IL-4) is an immunoregulatory cytokine produced by activated T lymphocytes to promote the growth and differentiation of cells that participate in immune defense. This study demonstrates the rapid activation of a specific DNA binding factor by IL-4. The IL-4 nuclear-activated factor (IL-4 NAF) appeared within minutes of IL-4 stimulation and recognized a specific DNA sequence found in the promoters of IL-4-responsive genes. Activation of this putative transcription factor required tyrosine phosphorylation, and antibodies specific for phosphotyrosine recognize the IL-4 NAF-DNA complex. Thus, IL-4 appears to transduce a signal to the nucleus through tyrosine phosphorylation of a latent DNA binding factor.
Evaluation of Transcendental Meditation as a Method of Reducing Stress
Authors: Michaels R. R. , Huber M. J. , McCann D. S.
Published: October 2006

Transcendental meditation is said to induce in its practitioners an altered state of consciousness resulting in relief of stress, an increased sense of awareness, and a sense of well-being. Release of catecholamines has been associated widely with stress and lends itself to quantitation. Plasma epinephrine and norephinephrine, as well as lactate, were measured in 12 volunteers before, during, and after meditation. Values were compared with those obtained from controls matched for sex and age who rested instead of meditating. Essentially the same results were obtained for the two groups, which suggests that meditation does not induce a unique metabolic state but is seen biochemically as a resting state.
Botulinum Toxin: Mechanism of Presynaptic Blockade
Authors: Kao Ing , Drachman Daniel B. , Price Donald L.
Published: October 2006

The mechanism of action of botulinum toxin was analyzed by the use of calcium ionophores and black widow spider venom. Addition of calcium ionophores to nerve-muscle preparations blocked by botulinum toxin did not increase the frequency of miniature end plate potentials. However, the spider venom elicited a barrage of miniature end plate potentials after blockade by botulinum. Electron micrographs of preparations treated with botulinum toxin and then the spider venom revealed clumping of synaptic vesicles at release sites in the otherwise depleted nerve terminals. These findings indicate that the action of botulinum toxin is not due to deficient storage of acetylcholine in vesicles or blockade of calcium entry into nerve terminals. They suggest that the toxin interferes with the acetylcholine release process itself, possibly by blocking exocytosis at the release sites.
Partial Amino Acid Sequence of the Precursor of Immunoglobulin Light Chain Programmed by Messenger RNA in Vitro
Authors: Schechter I. , McKean D. J. , Guyer R. , Terry W.
Published: October 2006

The five proteins programmed in a cell-free system by a mouse kappa light chain messenger RNA were labeled with [
3
H]leucine and subjected to amino acid sequence analyses. In all five proteins, 20 amino acid residues precede the amino terminus of the mature protein, indicating that there is one major point for the initiation of messenger RNA translation. The abundance (30 percent) of leucine residues in the extra piece (leucine at positions 6, 7, 8, 11, 12, and 13) indicates that this moiety is hydrophobic. Furthermore, it seems that the precursor may have an additional extra piece at the carboxyl terminus.
Hammondia hammondi
: A New Coccidium of Cats Producing Cysts in Muscle of Other Mammals
Authors: Frenkel J. K. , Dubey J. P.
Published: October 2006

Predominant muscle parasitism, and an obligatory two-host cycle (cat-mouse-cat), distinguishes an otherwise similar organism from
Toxoplasma
. The presence of multiplicative stages in the cat gut separate it from
Sarcocystis
. Antibody that cross reacts with
Toxoplasma
antigen is developed in mice and other experimental intermediary hosts, but not in cats, the final host. Recognition of the two-host cycle is essential for the experimental isolation and transmission of the parasite, and for prevention of the infection.
Modulation of Neuronal Migration by NMDA Receptors
Authors: Komuro Hitoshi , Rakic Pasko
Published: October 2006

The
N
-methy -D-aspartate (NMDA) subtype of the glutamate receptor is essential for neuronal differentiation and establishment or elimination of synapses in a developing brain. The activity of the NMDA receptor has now been shown to also regulate the migration of granule cells in slice preparations of the developing mouse cerebellum. First, blockade of NMDA receptors by specific antagonists resulted in the curtailment of cell migration. Second, enhancement of NMDA receptor activity by the removal of magnesium or by the application of glycine increased the rate of cell movement. Third, increase of endogenous extracellular glutamate by inhibition of its uptake accelerated the rate of cell migration. These results suggest that NMDA receptors may play an early role in the regulation of calcium-dependent cell migration before neurons reach their targets and form synaptic contacts.
Regulation of Gene Expression in Hippocampal Neurons by Distinct Calcium Signaling Pathways
Authors: Bading Hilmar , Ginty David D. , Greenberg Michael E.
Published: October 2006

Calcium ions (Ca
2+
) act as an intracellular second messenger and can enter neurons through various ion channels. Influx of Ca
2+
through distinct types of Ca
2+
channels may differentially activate biochemical processes.
N
-Methyl-D-aspartate (NMDA) receptors and L-type Ca
2+
channels, two major sites of Ca
2+
entry into hippocampal neurons, were found to transmit signals to the nucleus and regulated gene transcription through two distinct Ca
2+
signaling pathways. Activation of the multifunctional Ca
2+
-calmodulin-dependent protein kinase (CaM kinase) was evoked by stimulation of either NMDA receptors or L-type Ca
2+
channels; however, activation of CaM kinase appeared to be critical only for propagating the L-type Ca
2+
channel signal to the nucleus. Also, the NMDA receptor and L-type Ca
2+
channel pathways activated transcription by means of different cis-acting regulatory elements in the c-
fos
promoter. These results indicate that Ca
2+
, depending on its mode of entry into neurons, can activate two distinct signaling pathways. Differential signal processing may provide a mechanism by which Ca
2+
controls diverse cellular functions.
Rapid Loss of CD4
+
T Cells in Human-PBL-SCID Mice by Noncytopathic HIV Isolates
Authors: Mosier Donald E. , Gulizia Richard J. , MacIsaac Paul D. , Torbett Bruce E. , Levy Jay A.
Published: October 2006

Human immunodeficiency virus (HIV) isolates differ in cell tropism, replication, pathogenicity, and syncytial induction in vitro. CD4
+
T cells were enumerated in severe combined immunodeficient mice transplanted with human peripheral blood leukocytes (hu-PBL-SCID mice) and infected with HIV isolates with different in vitro cytopathicity. Two noncytopathic, macrophage-tropic strains, HIV-1
SF162
and HIV-2
UC1
, induced extensive CD4
+
T cell depletion, whereas HIV-1
SF33
, which is highly cytopathic for T cells in vitro, caused little CD4
+
T cell depletion at equivalent virus burden. In vitro cytopathicity assays therefore do not predict CD4 depletion in the hu-PBL-SCID model.
U2AF Homolog Required for Splicing in Vivo
Authors: Potashkin Judith , Naik Karuna , Wentz-Hunter Kelly
Published: October 2006

Several fission yeast temperature-sensitive mutants defective in pre-mRNA processing (
prp
-
mutants) at the nonpermissive temperature have been identified. Here, the
prp2
+
gene has been cloned by its ability to complement the temperature-sensitive growth defect of a
prp2
-
mutant. The gene also corrects the pre-mRNA splicing defect of
prp2
-
mutants and encodes a 59-kilodalton polypeptide (PRP2). A molecular characterization indicates that PRP2 is a previously uncharacterized yeast splicing factor with extensive similarity to the mammalian splicing factor U2AF
65
. Thus, this study provides evidence that a U2AF homolog participates in RNA processing in vivo.
Dense Nonsymmetrical DNA Methylation Resulting from Repeat-Induced Point Mutation in
Neurospora
Authors: Selker Eric U. , Fritz Deborah Y. , Singer Michael J.
Published: October 2006

Cytosine methylation has been implicated in epigenetic control of gene expression in animals, plants, and fungi. It has been assumed that all methylation in eukaryotes is at symmetrical sequences such as CpG/GpC, because this can explain perpetuation of methylation states. Here the bisulfite genomic sequencing method was used to examine methylation in DNA from a
Neurospora
gene exposed to repeat-induced point mutation. 5-Methylcytosine was not limited to symmetrical sites and individual molecules showed different patterns and amounts of modification. The methylation extended beyond the mutated region and even beyond the edge of the duplicated segment.