Search PubMed⌕ Search

Biomedical subjects

M L Nelson

Publications and source records attributed to M L Nelson.

10 recordsLinked to original sources
PubMed1992

Observation of the anterior supracostal muscles.

A pair of anomalous supernumerary muscles has been found in a single cadaver which fit the classic description of the Musculus supracostalis anterior. The muscles took origin from the first rib deep to the two pectoral muscles and between the origins of the pectoralis minor and serratus anterior muscles. They were directed inferiorly to insert on the upper margin of the fourth rib. The nerve supply of one muscle of the pair was determined to be from the collateral branch of the second right intercostal nerve. This supports the theory that these rare muscles may be derived from a single external intercostal muscle which grew to span several intercostal spaces.

Aged↗
PubMed1991

Decrease in resting metabolic rate during abstinence from bulimic behavior.

Among eight normal-weight bulimic women studied during 1 week of binge eating and vomiting and 7 weeks of abstinence without weight loss, resting metabolic rate and T3 and T4 levels fell significantly during abstinence. These data suggest that a physiological consequence of binge eating and vomiting is an increase in metabolic rate, in part due to increased thyroid hormone activity.

Adult↗
PubMed1990

Effects of rapeseed silage variety and dietary level on digestion and growth performance of beef steers.

A digestion and ruminal fermentation trial involving five ruminally cannulated steers assigned to a 5 x 5 Latin square with a 2 x 2 + 1 arrangement of dietary treatments was conducted to evaluate the effects of variety of rapeseed silage (RS) containing either a high (HG) or a low (LG) glucosinolate concentration when fed at 100 or 50% of diet DM. A bromegrass hay-corn-soybean meal mixture, which was expected to be isocaloric and isonitrogenous with the RS, was used as the control (C) treatment and replaced RS in the 50% diets. In situ disappearance of substrate from both RS varieties was measured in ruminal environments created by each diet. No dietary treatment x RS substrate interactions were observed for any in situ variable. Total tract digestibility and extent of in situ disappearance of both DM and NDF were greater (P less than .01) for HG than for LG. In situ DM and NDF disappearance at 8, 16 and 24 h was greater (P less than .01) for RS than for the C diet. Similarly, total tract DM digestibility was greater (P less than .01) for RS (61.0%) vs C (56.0%) diets. Diets with 50% RS had greater (P less than .01) NDF digestibility (50.4%) than 100% RS (43.6%) diets. Variety of RS had no effect on particulate passage rate. In a 77-d growth trial with 60 beef steers, ADG was greater (P less than .01) for HG vs LG (.46 vs .36 kg), 50 vs 100% (.52 vs .31) and C vs RS (.64 vs .41) diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Ovarian histopathology of bitches immunized with porcine zonae pellucidae.

The ovarian histopathology of bitches immunized with crude (cPZP) or partially purified (pPZP) porcine zona pellucida proteins was examined in order to determine the cause of abnormal estrous cycles. The majority of immunized bitches had ovarian cytes. Those immunized with cPZP had follicular cysts lined with a thin layer of granulosa cells, while in those immunized with pPZP, the cysts were lined by a basement membrane with a clump of luteinized cells. In two bitches immunized with cPZP, oocytes were present only in primordial follicles. Similar abnormalities were not found in a bitch immunized with human serum albumin or in 12 untreated bitches. Oocytes flushed from the oviducts of mated, immunized bitches were degenerating, which may have been a primary cause of infertility in such bitches. Ovaries studied 2-6 weeks after immunization showed no loss of gap junctional communication between oocytes and granulosa cells, nor was any inflammatory reaction seen. IgG was bound to the zona as revealed by fluoresceinated protein A staining of frozen sections of those ovaries. Abnormal estrous cycles in PZP-immunized bitches appear to result from follicular dysgenesis or cyst formation, but the etiology of these conditions is unresolved.

Animals↗
PubMed1975

Effects of simulated high altitude (3800 m) on reproductive function in the pregnant rat.

Ovarian appearance, uterine contents (including numbers of fetuses, size and weight), and levels of gonadotropic hormones were studied in pregnant rats exposed to simulated altitude (3800 m). Comparisons were made at 11, 20 and 21 days of gestation between sea level controls rats bred at sea level and placed at reduced barometric pressure on confirmation of pregnancy (SHA). Although fewer fetuses were present in SHA rats on day 11 of gestation, litter size at days 20 and 21 was similar to controls. Body weight and length of SHA fetuses were significantly reduced by day 21 of gestation while placental weights remained similar to controls. The follicle-stimulating hormone (FSH) content in the pituitaries of SHA rats was significantly reduced at days 11 and 21 of pregnancy as compared with controls; luteinizing hormone (LH) content was lower at day 20 than at day 11 among SHA rats. Plasma gonadotropin levels were similar between SHA and control rats all all three stages of gestation. It is suggested that, despite lack of placental adaptation and altered endocrine functions, exposure of rats to hypoxic conditions only during gestation permits better maintenance of pregnancy than reported in rats with longer exposure to high altitude.

Adaptation, Physiological↗
PubMed1975

Pituitary hormones and growth retardation in rats raised at simulated high altitude (3800m).

Growth and the endocrine status of the pituitary and thyroid glands were studied in rats born and raised in a hypobaric chamber at a simulated high altitude of 3800 m (SHA); comparisons were drawn with similar rats at sea level. From birth until 40 days of age, SHA rats weighed significantly less than controls with the most striking growth impairment found in female SHA rats. Relative organ weights of anterior pituitary glands, ovaries and uteri from 40-day-old female SHA rats were significantly less than controls. Pituitary content of growth hormone (GH) was reduced in 40-day-old female SHA rats while the content of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly increased over sea level controls. Plasma levels of GH, LH, FSH and thyrotropin (TSH) and pituitary TSH levels did not differ from control values. However, thyroidal uptake of 131I and plasma protein-bound 131I were significantly reduced in SHA rats as compared with controls. It is suggested that (1) the continuous exposure of developing female rats to hypoxia significantly impairs pituitary function and reproductive maturation, and (2) that despite other environmental factors acting on the developing organism at high altitude, growth retardation in rats born and raised at high altitudes is primarily a consequence of hypoxia.

Altitude↗