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At least 37 records · Page 2Linked to original sources
PubMed1992

Distribution of iodine into blood components of the Sprague-Dawley rat differs with the chemical form administered.

It has been reported previously that radioactivity derived from iodine distributes differently in the Sprague-Dawley rat depending on the chemical form administered (Thrall and Bull, 1990). In the present communication we report the differential distribution of radioactivity derived from iodine (I2) and iodide (I-) into blood components. Twice as much radioiodine is in the form of I- in the plasma of animals treated with 125I- compared to 125I2-treated rats. No I2 could be detected in the plasma. With an increase in dose, increasing amounts of radioactivity derived from 125I2-treated animals distribute to whole blood compared to equivalent doses of 125I-, reaching a maxima at a dose of 15.8 mumol I/kg body weight. Most of the radioactivity derived from I2 associates with serum proteins and lipids, in particular with albumin and cholesteryl iodide. These data indicate a differential distribution of radioactivity depending on whether it is administered as iodide or iodine. This is inconsistent with the commonly held view that iodine (I2) is reduced to iodide (I-) before it is absorbed systemically from the gastrointestinal tract.

Animals↗
PubMed1978

A comparison of the electrophoretic haemoglobin patterns of the vertebrates.

A comparative study of the haemoglobins of 648 animals distributed over 300 species of vertebrates and belonging to different classes has been made by horizontal starch gel electrophoresis is tris EDTA-borate pH 8.6. Multiple haemoglobins were found within the different classes. The percentage of multiple haemoglobins varies from class to class. The frequency-distribution of the mobility values of haemoglobins is rather specific for the different classes and in certain instances for the different orders.

Amphibians↗
PubMed1976

Characterization of the postnatal development of superior laryngeal nerve fibers in the postnatal kitten.

A combined electron microscopic and electrophysiological study of the superior laryngeal nerve (SLN) was undertaken in postnatal kittens ranging in age from 1-63 days. The superior laryngeal nerve is predominantly a sensory nerve innervating the upper respiratory tract, and could play a potential role in the modulation of respiration, particularly in the infant animal. Distribution of fibers in the developing SLN indicates that within the first postnatal month, 75% of the fibers are unmyelinated, and by 42 days, the myelinated fibers increase in number to approximately 50%. Of the myelinated fibers present in the one day old kitten, 3-4% of those exceeded 4 mum in total diameter, which is the minimum diameter for normal conduction velocity of action potentials. The distribution of the diameter sizes of the myelinated fibers is bell-shaped within the first 45 days after which the curve becomes skewed to the right (43-61 days; mean 2.6 mum, range 0.5-8.0 mum) to resemble the adult distribution of myelinated fibers (mean 4.2 mum, range 1.6-13.0 mum). Two variable plots of myelin width to axon diameter suggest a steeper slope for developing fibers as compared to that of the adult fibers. Electrical stimulation of the sectioned SLN indicates that evoked potentials could be recorded from the recurrent laryngeal nerve innervating the laryngeal intrinsic muscles and from the hypoglossal nerve to the tongue musculature in the youngest kittens tested (i.e., age 9 days). Stimulation at selected frequencies of 3 and 30/sec readily evoked apnea in the youngest kitten studied (i.e., age 5 days), while swallowing was more readily evoked at 28-30 days when using electrical stimulation.

Age Factors↗
PubMed2026

Genomic analysis of breed composition and population structure in Montana composite cattle.

The Montana composite was developed in Brazil from crosses between Bos indicus and Bos taurus and structured into four biological types: Zebu (N), adapted taurine (A), British taurine (B), and continental taurine (C). This study aimed to characterize the genetic diversity and population structure of the Montana composite using genomic data through principal component analysis (PCA), admixture analysis, and Wright's FST statistic. The PCA revealed a clear separation between Bos indicus and Bos taurus groups, with Montana animals distributed in an intermediate position. The first two principal components explained 69.48% and 3.45% of the total variation, respectively. Supervised admixture estimates indicated a predominance of taurine contribution, with type A accounting for 34.47%, 52.64%, and 51.71% at K&#x2009;=&#x2009;4, 9, and 11, respectively. Increasing the ancestry resolution refined the contribution of individual founder breeds without changing the overall predominance of taurine ancestry. Comparisons between breed proportions obtained from pedigree and genomic data revealed significant differences, for most biological types and ancestry models (P&#x2009;<&#x2009;0.001), indicating that realized breed composition deviates from theoretical expectations. Estimates of genetic differentiation confirmed greater divergence between Zebu and taurine groups, as well as reduced distances among populations sharing common ancestry. Specific relationships were identified between the composite and some of its founder breeds, particularly Belmont Red, Senepol, and Tuli. Overall, the results demonstrate that the Montana composite has a complex genomic structure, with genomic ancestry varying according to the resolution adopted and differing from pedigree-based expectations.

Animals↗
PubMed1977

[Resistance and biological tolerance of six "inert" parietal protheses. Experimental and critical study (author's transl)].

Six different materials (3 mesh and 3 cloth) commonly used for the repair of abdominal wall hernias were evaluated in rats. 490 animals, distributed among four experimental groups, were implanted with one of the different prostheses through musculature and peritoneum. Serial macroscopic and bacteriological investigations were done. Using an original device, bursting strength of the wound was determined in all groups at intervals. Histological criteria were used to characterize the resistance of the wound and the tolerance of the host to foreign material. Statistical analysis of the results demonstrated that: 1) after the 15th post-operative day, the resistance of the wound was similar for each material tested; 2) during this early period mesh materials exhibited more resistance to bursting pressures than cloth materials; 3) the incorporation of mesh material was constant whereas encystment or extrusion was always observed after implantation of cloth material; 4) no infection occurred with mesh material but significant bacteria were found in 18 p. 100 of cloth material implantations; 5) the extent of the cellular reaction, the enumeration of giant, inflammatory cells and fibroblasts showed superiority of mesh material; 6) the ratio of fibroblasts/inflammatory cells reflected closely the mechanical resistance and tolerance of the foreign material.

Animals↗
PubMed2014

Serial founder effects and genetic differentiation during worldwide range expansion of monarch butterflies.

Range expansions can result in founder effects, increasing genetic differentiation between expanding populations and reducing genetic diversity along the expansion front. However, few studies have addressed these effects in long-distance migratory species, for which high dispersal ability might counter the effects of genetic drift. Monarchs (Danaus plexippus) are best known for undertaking a long-distance annual migration in North America, but have also dispersed around the world to form populations that do not migrate or travel only short distances. Here, we used microsatellite markers to assess genetic differentiation among 18 monarch populations and to determine worldwide colonization routes. Our results indicate that North American monarch populations connected by land show limited differentiation, probably because of the monarch's ability to migrate long distances. Conversely, we found high genetic differentiation between populations separated by large bodies of water. Moreover, we show evidence for serial founder effects across the Pacific, suggesting stepwise dispersal from a North American origin. These findings demonstrate that genetic drift played a major role in shaping allele frequencies and created genetic differentiation among newly formed populations. Thus, range expansion can give rise to genetic differentiation and declines in genetic diversity, even in highly mobile species.

Animal Distribution↗
PubMed1977

[Important factors determining human distribution and elimination of diazepam].

The pharmacokinetics of diazepam and its biologically active major metabolite desmethyldiazepam were investigated under clinically relevant situations. Both drugs were measured in the different specimens (blood, plasma, urine, bile) by a specific and sensitive gas-liquid chromatographic assay. The pharmacokinetic data were analyzed by the digital computer program SAAM-25 according to the two compartment open model. In healthy subjects the elimination half-life (T1/2(beta))is dependent on the age of the individuals, which is caused by changes in the apparent volume of distribution. The strong plasma protein binding of 95 to 98 percent determines the low hepatic clearance of diazepam. Only neglible amounts of a dose are excreted unchanged with the bile and into the urine. After multiple dosing with diazepam its T1/2(beta) is prolonged, which is caused by a lowered clearance. Thereby also desmethyldiazepam accumulates, since it is eliminated about three times slower than its parent compound. In patients with dysfunction of the liver (cirrhosis, hepatitis) diazepam and desmethyldiazepam exhibit a prolonged T1/2(beta) and a reduced clearance and the lowered plasma protein binding causes a larger volume of distribution. Animal and in vitro experiments demonstrate, besides species dependent differences, that the elimination of diazepam can be impaired by the accumulating desmethyldiazepam.

Animals↗
PubMed1975

Distribution of gold Au 198 after intraperitoneal injection in animals.

The distribution of gold Au 198 after intraperitoneal administration in dogs and rats was determined by scans and tissue radioassays obtained 24 hours after injection. Relative activity and percent of injected radioisotope contained in different organs were calculated. The radioisotope was found to be heavily concentrated in mediastinal lymph nodes and liver, with liver uptake averaging 36.5% of the injected isotope 24 hours after injection. The use of therapeutic intracavitary radiocolloids should be reevaluated in light of possible excessive irradiation of the liver.

Abdomen↗
PubMed1977

Distribution and fate of the insect repellent 14C-N, N-diethyl-m-toluamide in the animal body. II. Distribution and excretion after cutaneous application.

The tissue distribution of 14C-labelled N,N-diethyl-m-toluamide (DEET), a widely used mosquito repellent, was studied by means of whole-body autoradiography after cutaneous application to mice. The early picture was very similar to that previously observed after intravenous injection of the substance, with high concentration of radioactivity mainly in the lacrimal gland, liver, bile, intestinal contents, kidney, urine, and nasal mucosa. Urinary excretion in mice was highest early after application whereas in a human volunteer maximal excretion appeared only after several hours. In mice a low but significant excretion persisted throughout the observation time of one month, probably emanating from the considerable amount of radioactivity remaining in the smeared skin area, as observed both autoradiographically and by means of quantitative measurements.

Administration, Topical↗
PubMed2026

The distribution of fitness effects of nonsynonymous mutations varies phylogenetically across animals.

The distribution of fitness effects (DFE) describes the selection coefficients of newly arising mutations and fundamentally influences population genetic processes. However, the extent and mechanisms of differences in the DFE for non-synonymous mutations have not been systematically investigated across species with divergent phylogenetic histories and ecologies. Here, we inferred the DFE in natural populations of 11 animal (sub)species, including humans, mice, fin whales, vaquitas, wolves, collared flycatchers, pied flycatchers, halictid bees, Drosophila, and mosquitoes. We found that mammals have a higher proportion of strongly deleterious mutations (defined as s&#x2264;-0.01; 22% to 47% in mammals; 0.0% to 5.4% in insects and birds) and a lower proportion of weakly deleterious mutations than insects and birds. Further, the DFE co-varies with phylogeny, such that the mean mutation effects are more similar in closely related species (Pagel's &#x3bb; = 0.84, P&#x2009;=&#x2009;0.01). Next, we investigated whether various summary statistics of the DFE were related to variation in life-history traits across these organisms. We found some support for genome size, body mass, and long-term effective population size being correlated with the DFE. Overall, our findings are consistent with predictions derived independently from the Fisher's Geometric Model (FGM), which defines organismal complexity as the number of phenotypes under selection. FGM predicts that mutations are more deleterious in complex organisms, while strongly deleterious mutations occur more frequently in smaller populations. Our study demonstrates strong phylogenetic signal in the evolution of a fundamental population genetics parameter, and proposes that, through mechanisms of epistasis, long-term population size and organismal complexity could be underlying variation in the DFE across animals.

Journal Article↗
PubMed1977

Distribution of S-adenosyl-L-(methyl-14C)methionine in animals.

The distribution of i.v. injected S-adenosyl-L-(methyl-14C) methionine was studied in the whole body of mice and in the cat brain using an autoradiographic technique. The drug was concentrated, at shorter survival times, mainly in the blood stream and in highly vascularized organs. Low concentration of radioactivity was found at longer times in the central nervous system (CNS). The quantitative analysis by means of organ radioassay was carried out in rats and confirmed the autoradiographic data.

Adipose Tissue↗
PubMed1977

Lung mast cell density and distribution in chronically hypoxic animals.

Changes in the density and distribution of pulmonary mast cells were determined in six mammalian species exposed to hypobaric hypoxia (PB = 435 Torr) for 19-48 days. Control animals were studied at 1,600 m (PB = 635 Torr). Total lung mast cell hyperplasia was observed only in calves exposed to high altitude. Pigs, rats, and sheep exhibited small, but insignificant, increases in mast cell density. Perivascular mast cell proliferation adjacent to vessels of 30-500 mum in diameter was seen in both calves and pigs. Bronchial, alveolar septal, and systemic tissue (tongue) mast cell hyperplasia was not observed in any of the species. Three indices of pulmonary hypertension (right ventricular hypertrophy, medial thickness of pulmonary arteries, and pulmonary arterial pressure) correlated with perivascular mast cell density. The findings indicate that perivascular mast cell proliferation may relate more to the morphological pulmonary vascular changes and to pulmonary hypertension than to hypoxia, leading to the speculation that mast cells increase in number in response to the hypertension, rather than to mediate and maintain the hypertension.

Animals↗
PubMed1976

Radiopharmaceuticals. 16. Halogenated dopamine analogs. Synthesis and radiolabeling of 6-iododopamine and tissue distribution studies in animals.

A simple halogenated derivative of dopamine, 6-iododopamine (1), has been synthesized using two different methods. These synthetic sequences have been applied to the radiolabeling of 1 with carbon-11, iodine-131, and iodine-123. The tissue distribution of 1 in mice, dogs, and rats was determined. The ratio of radioactivity (%/g) in the adrenal medulla-kidney in dogs increases from 3.45 at 2 h postinjection to 33.3 at 24 h postinjection. Thyroid uptakes in mice, dogs, and rats show that in vivo deiodination of 1 is not significant.

Adrenal Glands↗
PubMed1978

Carbon 11 labeling of the psychoactive drug o-methyl-bufotenine and its distribution in the animal organism.

A methylated derivative of serotonin, O-methyl-bufotenine has been labeled with 11C on the two methyl groups of the amine function. In order to avoid the cyclization which occurs during the Eschweiler-Clarke synthesis, we adopted a milder methylation procedure, based on Borch's method using [11C]formaldehyde and sodium cyanoborohydride. Several tens of millicuries of injectable product could be obtained in 50 min in a perfectly pure state and having a specific radioactivity of 50 to 100 mCi/mumol. The distribution study of O-methyl-bufotenine in the mouse and rabbit showed an accumulation of significant quantities of the compound in the brain, kidneys, lungs and liver. The study of the rapid kinetics of this hallucinogenic molecule is compatible with labeling by 11C, having a period of 20 min. The use of O-methyl-[11C]bufotenine to detect serotonin receptors in vivo in mental diseases, is considered.

Animals↗