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At least 1,747 records · Page 97Linked to original sources
PubMed1980

Control of prolactin secretion in mammals.

Evidence describing the neuroendocrine regulation of prolactin secretion in mammals is reviewed, with focus on catecholamines, serotonin, and polypeptides. Dopamine may be a physiological prolactin inhibiting factor (PIF), while norepinephrine and possibly epinephrine regulate prolactin release at the level of the hypothalamus. Serotonin may participate in the regulation of prolactin secretion by stimulating the release of prolactin releasing factor (PRF). The identity of PRF is not known, but two polypeptides--thyrotropin releasing hormone and vasoactive intestinal polypeptide--can act directly on the adenohypophysis to stimulate prolactin release.

Animals↗
PubMed1980

Glucose metabolism in the cornea and lens in elasmobranchs, teleosts and mammals: response to thiol-oxidation.

Various structural and metabolic adaptations that have occurred in elasmobranchs, in salt and fresh water teleosts, and in mammals have enabled these species to adapt to varied environments. In all cases the corneas of these species remain transparent and expend metabolic energy to maintain this transparency. The studies reported in this paper describe the structural and the metabolic adaptations that have occurred in these corneas. Included are measurements of corneal oxygen consumption, Q10 and corneal hydration. Thiol-oxidation of the intracellular glutathione with diamide has been shown to produce marked stimulation of the hexose-monophosphate shunt in the component layers of the cornea and the lens of rabbit, dogfish, and sculpin. Activities of glycolytic, citric acid cycle, and pentose phosphate shunt enzymes in the corneal and muscle tissue were also studied. Species variations were found between elasmobranchs, marine teleosts, and rabbits. In each of these species, the corneal endothelium was distinguished from the epithelium by much lower enzyme activities. It can be concluded that the enzyme activities and metabolic differences represent functional adaptations that have occurred to insure transparency under these extremely varied osmotic conditions.

Adaptation, Physiological↗
PubMed1982

Laelapidae (Acarina) of some small mammals from Toro game reserve, Uganda.

Laelapid mites of some small mammals from the Toro Game Reserve in Western Uganda were studied. The following species were determined: Laelaps (Echinolaelaps) muricola Trägãrdh, L. (E.) giganteus Berlese, L. (laelaps) grenieri Taufflieb, L. (L.) kampalensis Taufflieb, L. (L.) liberiensis Hirst, Androlaelaps callosus (Berlese) and A. zulu (Berlese). A female and a male of a new species Androlaelaps verneri sp. N. and up to now unknown males of A. callosus and L. kampalensis are described. All species found are briefly discussed.

Animals↗
PubMed1980

A study on the reservoir status of Q-fever in avifauna, wild mammals and poikilotherms in Uttar Pradesh (India).

Fifteen species of free-living birds (pigeon, mynah, house-sparrow, crow, vulture, owl, swallow, parrot, heron, duck, guinea fowl, hawk, kite, dove and peacock), 11 species of small/large wild mammals (rat, bandicoot, house mouse, shrew, bat, mongoose, ant eater, Jackal wild cat, chinkara and tiger) and 5 species of poikilotherms (snakes, python, tortoise, monitor and eel) were screened for evidence of Q-fever infection by the capillary agglutination test on sera to detect antibodies and/or by attempts to demonstrate Coxiella burnetii in samples of visceral organs. Sero-reactors were observed among mynah (19/69), owlet (1/6), pigeon (1/11), swallow (6/200), parrot (13/56), rat (3/21), shrew (1/24), bat (2/14) and snake (7/23). Eleven strains of the organism comprising 3 from mynah, 2 from rats, and 1 each from parrot, crow, swallow, bandicoot, chinkara and python were isolated. This appears to be the first record of natural Q-fever infection in free-living birds in India. C. burnetii was also recovered in 1 of 12 water samples processed from ponds. Possibility of contamination of ponds with C. burnetii from infected water-fauna has been discussed.

Animals↗
PubMed1978

[Protozoa of small mammals in the Neusiedlersee region].

During the years 1975 and 1976, 169 mammals (26 species) were investigated for their parasites. It was possible to recognise 33 different species of protozoans, belonging to the following genera: Trypanosoma, Giardia, Hexamita, Entamoeba, Eimeria, Isospora, Toxoplasma Frenkelia, Hepatozoon, Babesia, Balantidium, Pneumocytis, Grahamella, Eperythrozoon.--Epidemiology and eventual pathogenic effects are briefly discussed.

Animals↗
PubMedDate not supplied

[Ectoparasites of small mammals in the eastern portion of the Baikal-Amure mainline].

11.501 ectoparasites of 45 species were collected from small mammals (rodents, shrews and double-toothed rodents) in the north-eastern part of Priamurje. The parasitecoenoses are formed in general by gamasid mites (60.4%) and lice(24.7%) but faunistically fleas (19 species or 42.2%) are dominant. Among all ectoparasites the gamasid mites, Laelaps clethrionomydis and Hirstionyssus isabellinus, and the louse Hoplopleura acanthopus account for 64.9%. The impoverishment of the arthropod fauna in the northern part of Priamurje as compared to southern ones proceeds at the expence of chigger mites and more thermophilous species of gamasids and ixodids. With cultivation of forests the content of members of parasitecoenoses becomes more homogenous and their abundance falls.

Animals↗
PubMedDate not supplied

[Ectoparasites of small mammals, their nests and of the nests of birds in the floodplain of the Kamchatka River].

The paper presents data on the specific composition and abundance of bloodsucking arthropods parasitic on small mammals and birds in the valley of the Kamchatka river. One species of ixodids, I. lividus, 9 species of gamasids, P. crassipes, E. kraepelini, G. bispinosus, V. bujakova, H. casalis, H. mandschuricus, M. decoloratus, P. bujakovae, Macroheles sp., and one species of fleas, C. riparius, were first recorded from Kamchatka. 723 rodents were bacteriologically examined for tularemia with negative results.

Animals↗
PubMed1980

Scrub typhus survey of Biak and Owi islands: ectoparasites of small mammals and rickettsial isolations.

A survey of smnall mammals and their ectoparasites was conducted on the islands of Biak and Owi, Indonesia, in August 1976. Two species of chiggers known to serve as vectors of scrub typhus were found: Leptotrombidium (Leptotrombidium) deliense from Rattus exulans, R. ruber, and R. r. septicus; L. (L.) flectcheri from R. exulans, R. leucopus and R. r. septicus. Rickettsia tsutsugamushi was isolated from the spleens of R. exulans and R. r. septicus. The favored ecotype of the chigger and rat hosts of R. tsutsugamushi appeared to be coarse, low-lying native vegetation on a porous coralline soil. These and similar nearby coral islands should be considered high risk areas for scrub typhus.

Animals↗
PubMed1980

[Pharmacokinetic model studies of sulfamerazine in domestic mammals. 4. Mebacid tablet and Mebacid 200 dosage calculation problems].

The highly variegated complex of aspects relating to dosage calculation for veterinary drugs is explained and discussed by examples of Mebacid 200 and Mebacid tablets. For domestic mammals, a dosage interval of 24 hours is desirable for reasons of economy. Therefore, due allowance must be made, by means of unilateral confidence, of the most unfavourable case of high protein fixation, low half-life for elimination, and high coefficient of distribution. The following equation, proposed by DETTLI and SPRING (1966) was used for dosage calculation: AD = c . delta' . ek2 . t or ED = c . delta' . (ek2 . t -1) The dosage will now be in a twelve-hour rhythm, because of the low half-life for elimination of sulphamerazine-Na. A pharmacokinetically founded dosage interval of 24 hours will be feasible only by oral application of Mebacid tablets. The difference between the calculated initial and maintenance doses was found to be negligible.

Animals↗
PubMed1995

[Hematopoietic dynamics in mammals under combined radiation exposures (mathematical modelling)].

The mathematical models describing the dynamics of hemopoiesis in the mammals exposed to a combination of chronic irradiation are devised and studied. The models reproduce the increased radiosensitivity of the systems of thrombocytopoiesis, erythropoiesis and lymphopoiesis in the animals resulting from prolonged radiation exposure. Succeeding acute radiation exposure causes a more severe damage of the above-mentioned systems than it occurs for the species not being previously exposed to radiation. The model of granulocytopoiesis simulates both the decrease and the increase in radiosensitivity of this system due to the effect of chronic exposure using low and somewhat higher radiation doses, respectively. The postchronic acute radiation exposure has respectively the decreased or increased damaging effect. Within the limits of the models an interpretation of these effects is suggested. The results of modelling have an important theoretical significance in studies of the mechanisms of an effect of small doses of radiation on the mammalian organism as well as point to the perspectives of simulation experiments when evaluating the real radiation risks during long-term space missions.

Acute Disease↗
PubMed1978

Comparative anatomy of the caudate nucleus in different mammals.

Volumetric comparisons of the caudate nucleus of different mammals including rat, rabbit, cat, zebra, deer, antelope, bull, horse, dolphin (Stenella graffmani) and human are presented. A linear regression coefficient is obtained with its corresponding correlation coefficient. The results indicate that there is not a close correlation between the size of the caudate nucleus and the brain weight of the different animals studied when the caudate of the horse is included. When it is omitted there is a close correspondence. The caudate nucleus of the horse is extremely large in relation to its brain weight. The possible meaning of this fact is discussed. Measurement of different brain structures is of interest, both from the purely descriptive aspect and because it can suggest phylogenetic relations as well as explanation of functional differences in different animal species (1, 2).

Animals↗
PubMed1994

Arrangement of elastic fibres in the integument of domesticated mammals.

The hairy skin of important domesticated mammals (12 species) was studied with scanning electron microscopy, transmission electron microscopy, laser scanning microscopy, and several light microscopical methods, to obtain more information about three-dimensional elastic fibre arrangement. It was obvious that there is a basic construction scheme of the elastic fibre meshwork as present in the upper and mid-dermis, with special regard to the size, number, and grouping of hair follicles. In the densely-haired species, in particular, a typical elastic mat with horizontal fibres is formed. In many of the sparsely-haired animals, the upper and mid-dermis show a sponge-like elastic system. In the rather massive, collagen-rich skin of large species, the lower two thirds of the dermis without hair follicles only possess a loosely-structured elastic network, but thick elastic sheets are found at the border zone with the hypodermis. Specific features appear with regard to the type of mechanical strain exerted, different body regions, varying hair follicle density, or as connected with the anchoring of the hair follicle complex, blood vessels, and nerves.

Animals↗
PubMed1976

Metabolic consequences of submersion asphyxia in mammals and birds.

On submersion, the cardiovascular system of naturally diving animals is virtually transformed into a heart-brain-lung preparation as the result of intense and highly selective neurogenic vasoconstriction. A supply of oxygen from the circulating blood cells to the heart and the brain is thereby secured. Peripheral tissues, e.g. muscles and kidneys, have to depend on local stores of oxygen, i.e. myoglobin, or, when these are exhausted, on anaerobic metabolism. In spite of such physiological adjustments, however, arterial pO2 will inevitably decrease throughout the underwater episode. In prolonged dives values lower than 10mmHg can be observed. Moreover, the ischaemia in the peripheral tissues will, in some animals, e.g. arctic seals and whales, result in a profound decrease in the temperature of tissues such as the skin. The aim of the present report is to review some of the more important biochemical mechanisms that allow diving mammals and birds to cope with the above-mentioned combined asphyxic and temperature stresses for prolonged periods. Some of the osmotic problems arising from the rapid wash-out of acidic metabolic end products from the previously ischaemic tissues on emergence are also discussed.

Adaptation, Physiological↗
PubMedDate not supplied

[The characteristics of the effect of space flight factors on regeneration processes in mammals and Urodela].

Comparative analysis of experimental studies on regeneration of bone and muscle tissue under the influence of space flight factors (SFF) during restoration of experimental fracture in rats and epimorphic limb regeneration in adult newt is presented SFF-induced retardation of regeneration in mammals and its acceleration in tailed amphibians results from changed calcium metabolism in conditions of microgravity. Bidirectional effect of SFF on bone regeneration is due to specific control of calcium homeostasis in these taxa. Upon termination of the space flight (SF) the Wistar SPF rats proved to have increased functional activity of parathyrocytes and blocked calcitonin secretion to the blood by the C-cells of thyroid gland. Hence, inhibition of posttraumatic bone regeneration in rats is due to decreased formation rate and enhanced resorption of bony tissue. Sharp decrease of the calcitonincytes population following the initial hypertrophy of ultimobranchial gland (UBG) is observed in adult newt Pleurodeles waltlii Michah during SF. Progressing demineralization of skeletal elements including the amputated limb stump accelerates the first stages of its regeneration in conditions of SF.

Adaptation, Physiological↗
PubMed1994

[Parasitic arthropods from some species of wild mammals from middle Pomerania].

A total of 109 mammals belonging to 3 wild species: Cervus elaphus, Capreolus capreolus and Sus scrofa were examined post mortem after delivery by hunters to the warehouses of the "Jägerprodukt" company in Sławno and Osowo, and of the "Las" company in Sławsko (Middle Pomerania, Poland). Three species of ectoparasites were collected: Ixodes ricinus, Lipoptena cervi and Haematopinus apri. The highest frequency and the highest index of infestation with ectoparasites were observed in cause of C. elaphus. Lipoptena cervi was the most abundant species on C. elaphus and C. capreolus, and Haematopinus apri--on Sus scrofa.

Animals↗
PubMedDate not supplied

[Predatory terrestrial mammals--the definitive hosts of Diphyllobothrium klebanovskii].

To clarify the definitive hosts of Diphyllobothrium klebanovskii in the Far East, 2198 individuals of 18 terrestrial predatory and omnivorous mammal species were surveyed. It was established that 47.1 +/- 8.56% of brown bears, one of the two dissected black bears, 1.7 +/- 1.2% of wolves, 1.6 +/- 0.71% of dogs, 0.3 +/- 0.14% of American minks and 2.8 +/- 2.75% of pigs were invaded by a tapeworm. Obligatory hosts of the parasite were brown and black bears, and the remaining species were optional hosts of limited significance in maintaining parasite circulation.

Animals↗
PubMed1975

Interrelations between mammals and pathogens of some bacterial diseases.

Various interrelations of mammals with some bacterial pathogens are analyzed. Plaque and tularemia are the most thoroughly investigated infectious diseases in this respect. The importance of a different degree of susceptibility and sensitivity to infection for its development in mammalian reservoirs is underlined.

Animals↗
PubMed1993

Aspects of the neuroendocrine control of growth hormone secretion in ageing mammals.

In aged animals and humans the pulsatile secretion of growth hormone (GH), the mean amounts of GH released over 24 h, and the response of GH to the administration of GH-releasing hormone (GHRH) are lower than in young adults. Pituitary somatotrophic cells in old male and female rats show an impaired responsiveness to GHRH, and the reduced secretion of GH in vitro is linked with a diminished stimulation of adenylate cyclase by GHRH. Pretreatment with GHRH in vivo decreases the high basal adenylate cyclase activity in old male rats. This pretreatment does not affect the rise of adenylate cyclase concentration in these rats that is subsequently induced by GHRH administration in vitro. However, it does induce a small rise in adenylate cyclase concentration in old female rats. In young rats of either sex the same GHRH schedule does not alter adenylate cyclase activity, but it does reduce the effectiveness of subsequent acute exposure to GHRH to stimulate enzymatic activity. Short-term administration of GHRH in some aged subjects increases the response of GH to a subsequent acute challenge with GHRH. However, primary or secondary alterations in somatotrophic cells are also present in aged mammals, such as a reduction in the number of GH-immunoreactive structures or post-receptor alterations. In aged rats, major alterations in brain neurotransmitters and neuropeptides are present in hypothalamic and extrahypothalamic structures, especially in catecholaminergic and acetylcholinergic neurones. These alterations are probably due to defects in neurosecretory GHRH and somatostatin neurones. GHRH synthesis is impaired in the hypothalamus of senescent male rats, as shown by a reduction in GHRH mRNA levels and GHRH-like immunoreactivity. Although the expression of somatostatin seems to decrease with age in the rat hypothalamus, secretion and activity of this hormone is increased, resulting in an altered relationship between GHRH and somatostatin gene expression and secretion. Catecholamines induce GH release in most animal species by stimulating GHRH neurones and inhibiting somatostatin-releasing neurones. Acetylcholine stimulates GH release via muscarinic receptors, and thus inhibits the effect of somatostatin neurones. In male rats of various ages, except very young rats, systemic administration of pilocarpine, an agonist of muscarinic receptors, potentiates the GH response to GHRH during the entire lifespan.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗