bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative microscopic changes in the mole rat testes during an annual cycle
Authors: Gottreich Ahuva , Hammel Ilan , Yogev Leah , Terkel Joseph 
Published: February 2005

AbstractBackground: The mole rat Spalax ehrenbergi is a solitary, aggressive subterranean rodent. The present study summarizes a year‐round investigation of histological changes and sperm production in the mole rat testes.Methods: The testes were processed for routine histological examination. Tissues were fixed in Bouins' solution embedded in paraffin blocks and stained by hematoxylin‐eosin. A systemic sampling approach was used to photomicrograph the tissues for histomorphometric assessment.Results: Quantitative morphometry provided parameters indicating the activity of the tubuli testes during the year. The volume fraction of testes interstitial tissue from animals kept in captivity was unimodal and demonstrated an almost 3‐fold increase (from Vv = 0.19 ± 0.02 μm3/μm3 in October to 0.55 ± 0.05 μm3/μm3 in November) (i.e., early winter). The testes tubuli Vv of these animals demonstrated a significant decrease (from 0.75 ± 0.08 μm3/μm3 in October to 0.37 ± 0.04 μm3/μm3 in November).The testes tubuli star‐volume demonstrated an annual bi‐modal distribution, during winter (November‐February, v* = 0.075 ± 0.015 μm3) and summer (July‐August, v* = 0.085 ± 0.016 μm3); the lowest star‐volume was found in April (v* = 0.017 ± 0.004 μm3 in the field group).The testes tubuli revealed the entire sperm differntiation process throughout the year, from spermatogenesis (cells at all stages) to observation of mature spermatozoa, even though the mole rat is fertile only once a year during the winter. An increase in spermatogenesis and sperm production occurs during winter (Novermber‐December) and autumn (April‐May).Conclusion: It would appear that although changes in spermatogenesis and tissue structure are found during the annual cycle, the males none the less have a fecundity potential throughout the entire year. ± 1995 Wiley‐Liss, Inc.
Reducing the levels of formaldehyde exposure in gross anatomy laboratories
Authors: Coleman Raymond 
Published: February 2005

AbstractBackground: A method is described in which formaldehyde levels are greatly reduced in our gross anatomy laboratory in order to comply with increasingly severe safety and health regulations.Methods: A novel type of dissection “bed” has been introduced which incorporates an internal motor that causes a downflow of formaldehyderich vapors, which are absorbed by a replaceable active carbon filtration system.Results: Use of the new dissection “beds” has resulted in the recirculated air being virtually formaldehyde‐free. Formaldehyde vapor levels in our gross anatomy laboratory have been greatly reduced and are typically in the range of 0.03–0.09 ppm.Conclusions: The new system allows us to comply with safety and health regulations and provide a dissection room with an excellent working environment. © 1995 Wiley‐Liss, Inc.
Lipid‐lowering efficacy of 3,4‐di(OH)‐phenylpropionic L‐leucine in high‐cholesterol fed rats
Authors: Kim Soon‐Ja , Bok Song‐Hae , Lee SangKu , Lee Mi‐Kyung , Park Yong Bok , Kim Hye‐Jin , Choi Myung‐Sook 
Published: February 2005

AbstractA preliminary study revealed that 3,4‐di(OH)‐hydrocinnamate (HC), a polyphenolic compound, lowered the plasma lipids in high‐cholesterol fed rats. Accordingly, this study was designed to test the lipid‐lowering efficacy of a synthetic derivative, 3,4‐di(OH)‐phenylpropionic (L‐leucine) amide (PPLA), in rats fed a high‐cholesterol (1%, wt/wt) diet. As such, HC or PPLA was given as supplement to a high‐cholesterol diet for 6 weeks at a dose of 0.137 mmol/100 g diet. The supplementation of HC and PPLA significantly lowered the plasma and hepatic cholesterol and triglyceride levels compared to the control group. The activities of hepatic HMG‐CoA reductase (164 ± 9.12 and 124.74 ± 17.09 pmol/min/mg protein vs. 245.41 ± 13.01 pmol/min/mg protein, p < 0.05) and ACAT (411.49 ± 11.48 and 334.35 ± 17.68 pmol/min/mg protein vs. 490.41 ± 16.69 pmol/min/mg protein, p < 0.05) were significantly lower in the HC‐ and PPLA‐supplemented groups than in the control group. However, PPLA was more effective in inhibiting the enzyme activities than HC. The excretion of neutral sterol was significantly higher in HC‐ and PPLA‐supplemented groups than in the control group. Therefore, these results indicate that PPLA, a leucine‐attached version of HC, exhibited a similar significant hypocholesterolemic effect to HC in rats fed a high‐cholesterol diet. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:25–31, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20054
Pattern of CO2 fixation during vegetative development and gametic differentiation in Chlamydomonas reinhardtii
Authors: Kates Joseph R. , Jones Raymond F. 
Published: February 2005

AbstractThe rate of C14O2 incorporation into amino acids and organic acids in C. reinhardtii is a function of particular stages of development in the life cycle of the alga. Gametic differentiation in nitrogen free medium is accompanied by a reduced rate of amino acid synthesis and a higher synthesis of organic acids than that found for the cells undergoing vegetative development. The addition of ammonium to differentiating gametes results in an increased synthesis of amino acids, particularly the basic ones, and a concomitant reduction in organic acid synthesis.
Heat production during diving in the fresh water turtle, Pseudemys scripta
Authors: Jackson Donald C. , Schmidt‐Nielsen Knut 
Published: February 2005

AbstractHeat production was measured calorimetrically in the turtle, Pseudemys scripta elegans, (a) while submerged and (b) while partially submerged and breathing various gas mixtures. Submersion resulted in a profound reduction of heat production (80%). This reduction was not merely a response to the dive per se, but depended on the oxygen concentration available to the turtle prior to the onset of the dive. Heat production while breathing gas mixtures with different O2 concentrations was unchanged down to 5% O2. At 3% O2, heat production was 50% of normal, and at 100% N2, it was 20% of normal. Uptake of dissolved O2 from water was found to be 6% of the O2 uptake from air by these turtles. These results suggest that following diving, there is a profound reduction in metabolic rate, but not until the O2 stores are depleted. This low rate is primarily anaerobic and only a very low oxidative metabolism can be supported by O2 extracted from the water.
The effect of hematoporphyrin and light on human platelets. I. Morphologic, functional, and biochemical changes
Authors: Zieve Philip D. , Solomon Harvey M. , Krevans Julius R. 
Published: February 2005

AbstractThe morphologic, functional, and biochemical changes produced by hematoporphyrin and light in human platelets have been characterized. by phase microscopy the cells appeared swollen and resembled signet rings; by electron microscopy they showed considerable loss of cytoplasm and their contour was smoother than normal. irradiated platelets were not aggregable by thrombin and calcium chloride, although they contained clottable protein, and were incapable of supporting clot retraction. a linear relationship was demonstrated between the per cent depletion of serotonin from irradiated platelets and the log dose of hematoporphyrin. the depletion of serotonin from these platelets was related lineraly to the log of time of exposure to light during the initial six minutes of exposure; but thereafter continued at a constant rate. the temperature of incubation influenced directly the rate of depletion of serotonin from irradiated platelets but did not influence the movement of serotonin into these platelets. atp was diminished considerably in irradiated platelets. these changes are attributable to damage to the membrane of the platelet by hematoporphyrin and light.These studies provide additional information about the blood platelet in terms of its response to photodynamic action.
Circadian activity rhythms in cockroaches. III. The role of endocrine and neural factors
Authors: Def. Roberts Shepherd K. 
Published: February 2005

AbstractThe control of circadian activity rhythms (diurnal rhythms) in insects has been suggested to result by periodic neuroendocrine secretions. More specifically, Harker ('56) claimed that the locomotor rhythm in the cockroach, Periplaneta americana, is timed by a secretory “clock” located in the subesophageal ganglion. Later experiments by Harker indicated that this “clock” function failed unless the retrocerebral organs were left intact; allatectomy was said (no evidence given) to abolish a rhythm. The procedure for demonstrating a “clock” function in the ganglion involved transplanting it from a rhythmic donor into the hemocoel of an arrhythmic host and observing that the host subsequently became rhythmic. This result (without explicit information about the phase of the rhythm) does not warrant the conclusion that the ganglion acts as a clock. Therefore, I have attempted to confirm and extend these important results. Employing techniques essentially identical to Harker's, and using the same species of roach, I have been unable to find any evidence to support the original claim: (1) in 20 test animals, implantation of ganglia from rhythmic donors failed to re‐instate a rhythm, and (2) allatectomy (22 cases) or removal of the entire retrocerebral complex (20 cases) did not interfere with the rhythm.The results of another series of experiments show that the cockroach brain is involved in the control of the activity rhythm. When the brain is surgically bisected (mid‐sagittal) through the pars intercerebralis, arrhythmic activity patterns are immediately evoked. These continue for many weeks, but in a few cases rhythms ultimately “regenerate”.
Purine pyrophosphorylase as a selective genetic marker in a mouse lymphoma, P388, in cell culture
Authors: Ozer Harvey L. 
Published: February 2005

AbstractIt is possible to use the purine pyrophosphorylase in mammalian cell culture systems as a genetic marker in selecting small numbers of enzyme positive cells from large populations of pyrophosphorylase negative cells of the mouse lymphoma line P388 in medium containing amethopterin, hypoxanthine, glycine and thymidine. Conversely, it is readily possible to obtain pyrophosphorylase‐deficient cells by treatment with 8‐Azaguanine. We were unsuccessful in demonstrating DNA‐mediated transformation using DNA from enzyme positive cells incubated with cells which were enzyme negative.
Lysosomes in Tetrahymena pyriformis I. Some properties and lysosomal localization of acid hydrolases
Authors: Müller Miklós , Baudhuin Pierre , De Duve Christian 
Published: February 2005

AbstractIn homogenates of Tetrahymena pyriformis, five hydrolases — phosphatase, ribonuclease, deoxyribonuclease, proteinase, amylase — with acid pH optima were found. Over 75% of their activity is sedimentable with a centrifugal force of 250,000 g. min. Only 17% of the acid phosphatase and ribonuclease is active when assayed in the presence of 0.25 M sucrose at 0°. Exposure to a lowered osmotic pressure, freezing and thawing, and incubation at temperatures over 0° result in activation of the latent phosphatase and ribonuclease. After isopycnic centrifugation in a sucrose density gradient the hydrolases show a broad distribution which differs greatly from those of enzymes associated with mitochondria (succinate dehydrogenase) or with peroxisomes (catalase). The results are interpreted as evidence that the five acid hydrolases studied are localized in lysosomes which represent a distinct population of subcellular particles in Tetrahymena.
Studies on carcinogenesis by avian sarcoma viruses. V. Requirement for new DNA synthesis and for cell division
Authors: Temin Howard M. 
Published: February 2005

AbstractPartially synchronized secondary cultures of chicken embryo fibroblasts were exposed to Rous sarcoma virus (RSV) at various times in the cell cycle. The initiation of normal virus production could be inhibited by treatment with excess thymidine or with cytosine arabinoside without any effect on mitosis. This result is consistent with the hypothesis that the provirus of RSV is DNA, although the virion of RSV contains only RNA. It was, also, found that treatment which prevented or interferred with the first mitosis after exposure to virus prevented the initiation of normal virus production. Later mitoses did not appear to be necessary. A corollary of this finding is that virus production is synchronized by mitosis and that the length of the latent period depends upon when in the cell cycle a cell is exposed to virus.
A cytological study of the capacity for differentiation of normal hemopoietic colony‐forming cells
Authors: Wu A. M. , Till J. E. , Siminovitch L. , McCulloch E. A. 
Published: February 2005

AbstractA two‐stage procedure has been used to obtain hemopoietic spleen colonies derived from single precursor cells containing radiation‐induced chromosomal markers. Of a total of 46 colonies examined, 17 were found to contain cells with abnormal karyotypes. In each of the 17 marked colonies, 90% or more of the dividing cells in the colony carried the same marker. Cell suspensions prepared from each of the individual colonies were tested for their content of dividing cells possessing recognizable differentiated functions. Metaphase cells with peroxidase‐positive granules in their cytoplasm were considered to be members of the granulopoietic series, while metaphase cells which contained Fe55 were considered to be members of the erythropoietic series. Results were obtained for 12 of the marked colonies, and in nine of these, the percentage of metaphases lacking the marker was less than the percentage of metaphases which were scored as erythropoietic, and also was less than the percentage of metaphases scored as granulopoietic. This is the result which would be expected if the marker were present in both erythropoietic and granulopoietic cells. These results provide support for the view that colony forming hemopoietic stem cells are multipotent, and that differentiation along more than one pathway can occur during the formation of macroscopic splenic colonies.
Variation in fructose transport among beef erythrocytes
Authors: Laris Philip C. 
Published: February 2005

AbstractErythrocytes from different cattle were shown to fall into two distinct groups with respect to fructose transport. The rates of entrance of fructose into the two classes of cells differed by a factor of 5 to 10. It was also found that one pathway, the slower, was susceptible to inhibition by glucose while the other was not. The characteristics of the two fructose transport systems remained constant for as long as a week (longest time studied) upon storage at 2°C. The differences observed could not be attributed to handling of the blood, to the relative glucose permeability, or to the age or sex of the animal. This work indicates that two different fructose transport systems are operating in beef erythrocytes of different individuals.
Delay in the cleavage of Tetrahymena pyriformis exposed to high hydrostatic pressure
Authors: MacDonald A. G. 
Published: February 2005

AbstractEarly cleavage stages of Tetrahymena pyriformis were exposed to 250 atms pressure for periods ranging from 20–200 minutes. Pressure halted cleavage which, in those cells exposed for only a short time, was resumed soon after decompression. Cells exposed to longer periods of pressure treatment failed to resume cleavage soon after decompression but cleaved after a delay approximating to a generation time. In the former case, the cleavage furrow remained intact; whereas in the latter case, the cleavage furrow frequently resorbed and a new furrow was formed to accomplish the delayed cleavage.The results appear consistent with the hypothesis that the hypothetical macro‐molecular entity P2 of Rasmussen and Zeuthen is pressure labile and involved in the mechanical process of cleavage.
Application of irreversible thermodynamics to a functional description of the tumor cell membrane
Authors: Hempling H. G. 
Published: February 2005

AbstractThe permeability of the membranes of several strains of Ehrlich mouse ascites tumor cells to a series of homologous glycols was analyzed with equations from irreversible thermodynamics. Experimental data were fitted to the appropriate equations of Kedem and Katchalsky by means of an analog computer and values for σ, Lp, and ωRT were calculated. These parameters would become part of a functional profile of the membrane of the tumor cell. The glycols cross the membrane with energies of activation ranging from 16 kcal/mole for ethylene glycol to 20 kcal/mole for triethylene glycol. Entropies of activation ranged from 17 to 27 entropy units. This analysis provided several additional dividends. It is one of the few examples with a mammalian cell where the kinetics of non‐electrolyte transport have been described completely by the equations of irreversible thermodynamics. It has provided the means to distinguish how much of the transport occurred through porous paths in the membrane and how much involved solution within the matrix of the membrane. Finally, several tumor cell populations have been distinguished through these functional properties of their membranes.
Cytidine aminohydrolase activity in intact cultured transformed cells
Authors: Ellem K. A. O. 
Published: February 2005

AbstractCultures of several cell lines convert cytidine, if present in their medium, to uridine. The reaction is rapid, being virtually complete within one hour. The enzymatic activity is that of cytidine aminohydrolase (EC 3.5.4.5). The activity is exhibited by the intact cell — substrate and products being found in the medium bathing the cells. The activity should be taken into account in studies involving cytidine, and other 6‐amino pyrimidine nuclecsides.Of nine transformed cell lines, and nine primary and secondary cell strains screened for the presence of cytidine aminohydrolase activity, six cultures were positive. All the positive cultures were heteroploid transformed lines. No diploid strain cultures were positive, and two near diploid mouse lymphoid neoplasms were negative. PPLO contamination was not detected in the positive cultures.Within the limited series of cell cultures screened in this study, there appears to be a correlation between heteroploidy and the ability of the intact cultures to deaminate cytidine in excess of the cell requirement for the precursor.
Production of heparin related glycosaminoglycans by an established mammalian cell line
Authors: Kraemer Paul M. 
Published: February 2005

AbstractA sulfated glycosaminoglycan has been isolated from the acid‐soluble fraction of an established line of Chinese hamster fibroblasts grown in suspension culture. This material has a molecular weight between 5000 and 10,000, contains equimolar amounts of hexosamine and uronic acid (orcinol method), and about 0.6 sulfate groups per hexosamine residue. About 80% of the sulfate groups are N‐sulfates on the basis of lability of the sulfate and the formation of equivalent numbers of free amino groups upon mild acid hydrolysis. The material is completely resistant to testicular hyaluronidase but is degraded to reducing monosaccharides and small oligosaccharides upon treatment with lyophilized cells of Flavobacterium heparinum that were grown on heparin. It is thought, therefore, to be related to the known N‐sulfated glycosaminoglycans heparin and heparitin sulfate.
Differentiation of antibody forming cells in lymph nodes during the anamnestic response
Authors: Schoenberg M. D. , Moore R. D. , Stavitsky A. B. , Gusdon J. P. 
Published: February 2005

AbstractThe cellular and subcellular events in the anamnestic response were considered. Rabbits previously immunized with key hole limpet hemocyanin (KLH) were given an anamnestic challenge in the hind footpads. The popliteal lymph nodes were removed at intervals after immunization and the following correlated on a temporal basis: the changes in the number and types of cells in the lymph nodes; the formation and regression of ribosomes, polyribosomes, endoplasmic reticulum and Golgi apparatus in plasma cells; the changes in intracellular immunofluorescence for anti‐hemocyanin; and, the incorporation of 14C labeled amino acids by lymph node cells into anti‐KLH during a brief in vitro culture period.Maximum intracellular fluorescence for anti‐KLH and the largest incorporation of 14C labeled amino acids into antibody occurred between the third and fourth day after immunization. During this interval highly differentiated plasma cells were most numerous with respect to the total cellular population. These events took place in a 12 to 24 hour period.This was followed by an abrupt decline in the synthesis of antibody. Coincident with this was a reduction in the number of recognizable plasma cells in the nodes, diminished intracellular fluorescence for anti‐KLH and a simplification of the cytoplasm of the plasma cells toward a lymphocytic form.
A study of the intracellular transport of calcium in rat heart
Authors: Patriarca P. , Carafoli E. 
Published: February 2005

AbstractThe distribution of in vivo injected 45Ca++ in the subcellular fractions of rat heart has been studied. Most of the radioactivity of the cell was found to be associated with the subcellular organelles; only a small fraction was recovered in the soluble phase. Mitochondria contained the greatest part of the total radioactivity associated with the subcellular organelles. After injection of 45Ca++ the specific activity of the mitochondrial calcium pool was several times higher than that of the calcium of the sarcoplasmic reticulum. Pentachlorophenol has been administered to rats to uncouple oxidative phosphorylation in heart mitochondria in vivo and its effect on the distribution of 45Ca++ in the heart studied. Under these conditions, it has been found that mitochondria contained much less 45Ca++ than the controls; this decrease was paralleled by an increase of the radioactivity associated with the microsomes and with the final supernatant. Experiments in which 45Ca++ was added to heart homogenates at 0° indicated that 45Ca++ also became bound to mitochondria and the other subcellular structures at 0°. However, PCP had no effect on the distribution of radioactivity among the subcellular fractions under these conditions. The results suggest that (1) energy‐linked movements of Ca++ take place in mitochondria of the intact rat heart, (2) a part of the uptake of 45Ca++ by mitochondria does not depend on metabolism, and, (3) the movements of Ca++ in heart mitochondria in vivo are probably more active than those in the sarcoplasmic reticulum.
Specificity of carotenoid transfer in the larval medaka, Oryzias latipes
Authors: Takeuchi Kunisuke 
Published: February 2005

AbstractCarotenoids were introduced into the egg yolk of the medaka by either injection or feeding. Carotenoids for injection were dissolved in either olive oil, a mixture of olive oil and castor oil or Tween 80. Capsanthin, lutein and canthaxanthin were readily transferred from the yolk to the larval xanthophores, but no β‐apo‐8′‐carotenal and little β‐carotene were transferred.
The effect of DMSO on the permeation of non‐electrolytes through the barnacle cell membrane
Authors: Bunch Wilton H. 
Published: February 2005

AbstractFrequent reports have suggested that Dimethylsulfoxide (DMSO) increases the flux of other molecules through biological membranes. This paper reports experiments in the single barnacle cell which permits differentiation of trans‐membrane fluxes from those utilizing intercellular pathways. Several non‐electrolytes were injected and wash‐out rates observed. There was no change in the time course of the wash‐out of these molecules when DMSO was added to the injected fluid. The conclusion of these experiments is that DMSO in low concentration does not change the permeation of non‐electrolyte across the cell membrane.