PubMed Health⌕ Search

Biomedical subjects

M B Anderson

Publications and source records attributed to M B Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Multiple sites of action of the vitamin D endocrine system: FSH stimulation of testis 1,25-dihydroxyvitamin D3 receptors.

1,25-Dihydroxyvitamin D [1,25(OH)2D] receptors exist in numerous unexpected tissues. These include, for example, rat lung, heart, testis, and uterus, but not prostate and bladder. The issues of 1,25(OH)2D effects on and receptor location in the testis were addressed by (a) physiological and pharmacological manipulations of tubule cell types and (b) histological examination of testes of vitamin D-deficient rats. FSH treatment in hypophysectomized adult rats increased 1,25(OH)2D receptor levels by 135% (P less than 0.01). Busulfan treatment reduced testis receptor levels by 35% (P less than 0.05) after 35 days (maximum effect), and the effect was reversed after recovery (85 d). Cryptorchidism for 5 or 50 days resulted in modest (33%, P less than 0.05) or substantial (79%, P less than 0.001) reductions in receptor levels. Only the FSH treatment and 50 days cryptorchidism reduced receptor levels in the residual tissue. The testes of vit. D-deficient rats showed incomplete spermatogenesis and degenerative changes. Although interpretation is complicated by the intricate communication among testis cell types, these data suggest that the Sertoli cell is a primary site of action of 1,25(OH)2D in the testis. Moreover, these data indicate that 1,25(OH)2D receptor function in the testis relates to germ cell division/maturation, although this may be an indirect effect via the Sertoli cells.

Animals↗
PubMed1988

Effects of acute and chronic exposure to cobalt on male reproduction in mice.

Chronic exposure of male mice to cobaltous chloride dramatically affected their reproductive potential, while acute administration had minimal effects. Acute exposure, followed by evaluation weekly over a 7-week period, revealed no significant changes in epididymal sperm concentration or testicular weight. However, small but significant decreases in fertility at weeks 2 and 3 of the study were observed. Sperm motility was depressed only during the first week of the study. In chronic studies, cobalt affected fertility in a time- and dose-dependent manner. There was a decrease in testicular weight, epididymal sperm concentration, and fertility. Sperm motility was also depressed. Serum testosterone levels were dramatically increased in cobalt treated animals, while FSH and LH serum levels were normal. It appears that cobalt is directly or indirectly interfering with spermatogenesis and with local regulatory mechanisms in testosterone synthesis.

Animals↗
PubMed1988

The source of relaxin in pregnant Syrian hamsters.

Serum immunoreactive relaxin (IR) was measured on days 8, 10, and 14 of gestation in intact and ovariectomized (day 8 of pregnancy) hamsters. In intact hamsters, IR increased from 3-4 ng/ml on day 8 to 20 ng/ml by day 14 of pregnancy. After ovariectomy on day 8, pregnancy failed, and IR decreased rapidly to 0.29 ng/ml on day 14. However, when pregnancy was maintained in ovariectomized hamsters by daily injections of 0.1 microgram 17 beta-estradiol and 4 mg progesterone, serum IR rose to levels similar to those in intact hamsters on days 10 and 14 of pregnancy (i.e. 15 and 20 ng/ml, respectively). Placentas were obtained from other groups of hamsters on days 11, 14, and 15 of pregnancy and homogenized for bioassay by the classical guinea pig pubic symphysis palpation bioassay. Homogenates of placentas obtained on days 14 and 15 contained, respectively, 4 and 10 micrograms eq porcine relaxin/serum relaxin/g fresh tissue. The placenta, rather than the ovary, appears to be the source of during pregnancy in the hamster.

Animals↗
PubMed1986

Absence of relaxin immunostaining in the male reproductive tracts of the rat and mouse.

By use of the biotin-avidin immunohistochemical method and a homologous antiserum as the primary antiserum, relaxin immunostaining was absent in the testes, prostate, seminal vesicles, and epididymides of the rat. Relaxin immunostaining was also lacking when anti-porcine relaxin serum was employed as the primary antiserum. Furthermore, immunohistochemical studies for relaxin localization in the reproductive tract of the male mouse using both anti-rat and anti-porcine relaxin sera also revealed an absence of the hormone in the reproductive system of this species. Although this study suggests that immunoreactive relaxin is absent in the male reproductive tracts of both the rat and mouse, it raises some questions concerning the reports in the literature of the presence of relaxin-like substances in the male reproductive tracts of other species. These reports are discussed in relation to our current results.

Animals↗
PubMed1985

Spinal arthrodesis for spinal deformity using posterior instrumentation and sublaminar wiring. A preliminary report of 100 consecutive cases.

One hundred consecutive patients with spinal deformity due to various diagnoses were treated by posterior spinal arthrodesis with instrumentation and multiple sublaminar wires. Both the Harrington and Luque rodding systems were used. A total of 1128 wire loops were passed. No patient developed paraparesis or paraplegia, but three had transient sensory disturbance. There were no cases of broken rods or wires. Forty-five of the patients had no postoperative support. This worked well for neuromuscular scolioses, but for idiopathic scoliosis there was a disturbing loss of correction in many cases. Fusion to the sacrum was best accomplished with the "Galveston" technique, other methods having a high rate of pseudarthrosis. The main benefits appeared to be the ability to stabilize neuromuscular patients without the use of external immbolization, and the correction of thoracic lordosis.

Adolescent↗
PubMed1985

Immunocytochemical studies of relaxin in ovaries of pregnant and cycling mice.

Immunocytochemical staining for relaxin in ovarian sections of pregnant mice from day 11 through day 18 of gestation revealed that only corpora lutea (CL) of pregnancy are stained. Evaluation of serial sections of ovaries from a day 16 pregnant mouse revealed that the only luteal structures present are CL of pregnancy. The number of CL present in each ovary equaled the number of implantation sites in each related horn (7 on the right side and 8 on the left side). These large CL varied in shape, being round in some profiles to very elongate in others. All CL were immunochemically stained for relaxin using the peroxidase-antiperoxidase method of L. Sternberger (Immunocytochemistry, 2nd ed. Wiley, New York, 1979). The intensity of the strain varied from cell to cell within each CL. Small luteal structures that were observed to be immunochemically stained for relaxin were demonstrated to represent the periphery of CL of pregnancy. No luteinized follicles were observed and interstitial cells and follicles were not immunochemically stained in any of the day 16 serial ovarian sections or in any of the ovarian sections from pregnant mice on the other days of gestation studied. CL of previous cycles were not observed to be present in the ovaries at days 15, 16, or 18 of gestation. However on day 14 and before, CL of previous cycles were observed and they did not exhibit any relaxin immunostaining. Immunocytochemical studies using the biotin-avidin system revealed that no relaxin immunostaining could be demonstrated in the ovaries of cycling mice at any stage of the estrous cycle. In conclusion, this study revealed that the only ovarian structures demonstrating relaxin immunocytochemical staining in the mouse were CL of pregnancy.

Animals↗
PubMed1984

Pregnant mouse corpora lutea: immunocytochemical localization of relaxin and ultrastructure.

Relaxin was localized in corpora lutea of pregnant mouse ovaries by using the unlabeled antibody peroxidase-antiperoxidase technique and a highly specific rabbit antirat relaxin serum. Relaxin immunostaining was first observed in luteal cells located at the periphery of corpora lutea on Day 10 of gestation. The number of relaxin immunostained cells and the intensity of the stain gradually increased to reach a maximum between Days 16 and 18 of gestation. While a few luteal cells were specifically stained for relaxin on Day 1 postpartum, no luteal cells were stained on Day 2 postpartum. Ultrastructural studies of luteal cells from pregnant mouse ovaries revealed the presence of a distinct electron-dense, membrane-bound granule population, which was first observed on Day 12 of gestation. The granules increased in number to reach a maximum between Days 16 and 18 of gestation, and were absent by Day 2 postpartum. The appearance and disappearance of this granule population closely paralleled the relaxin immunostaining in the luteal cells. We suggest that the granules may be the subcellular sites of relaxin storage in the pregnant mouse ovary.

Animals↗
PubMed1984

Bioassay of porcine relaxin components by in vitro inhibition of rat uterine contractions.

Isolation of porcine relaxin by the procedure of Sherwood and O'Byrne has resulted in three, slightly different relaxin molecules which differ in the length of their B chains. The purpose of this study was to determine if a difference in biological activity exists among the three relaxin forms as determined by the in vitro inhibition of spontaneous rat uterine contractions. Uterine segments from estrogen-primed, virgin rats were suspended in Locke's solution in a siliconized, water-jacketed organ bath at 37 C. After regular contractions were established, the minimum concentration of each relaxin component necessary to cause total inhibition was determined. Total inhibition for all three relaxin components was obtained at a chamber concentration of 0.2-0.36 U/ml. Thus, no difference in biological activity exists among the three relaxin forms as demonstrated by the rat uterine inhibition bioassay.

Animals↗
PubMed1984

Ultrastructural localization of relaxin immunoreactivity in corpora lutea of pregnant rats.

Relaxin was localized in cells of corpora lutea of pregnant rats at the ultrastructural level using a highly specific antirat relaxin serum and the unlabeled peroxidase-antiperoxidase technique. Electron-dense, membrane-bound granules (maximum diameter, 270 nm), which are present in luteal cells during the last third of gestation, were the only inclusions that were immunochemically stained. The number of granules observed in the luteal cell cytoplasm varied from cell to cell within a particular section. Furthermore, in the granule-rich luteal cells, the granules appeared in clusters. This study establishes that these electron-dense granules represent the subcellular sites of relaxin localization within luteal cells of pregnant rats.

Animals↗
PubMed1969

Differences in leucyl-transfer rna's and synthetase in soybean seedlings.

Charged leucyl-transfer RNA (leucyl-tRNA) of soybean cotyledons can be fractionated into six radioactive peaks on a Freon column. Four leucyl-tRNA peaks are observed with the homologous hypocotyl system. Hypocotyl synthetase preparations only slightly acylate the other two leucyl-tRNA's (species 5 and 6). Further, leucyl-tRNA(5 and 6) of the hypocotyl are present in small amounts in comparison to the cotyledon. Therefore, the rate-limiting quantities of synthetase and tRNA(5 and 6) obtained from the hypocotyl prevent the detection of these two species of tRNA when a homologous hypocotyl system is used. To measure the relative amounts of hypocotyl tRNA's, the cotyledon synthetase preparation is employed. Preliminary results show that 6-benzyladenine increases the acylation of leucyl-tRNA(5 and 6) and decreases acylation of tRNA(1) in the hypocotyl. Synthetase preparations from cytokinin-treated plants are not significantly affected.

Journal Article↗
PubMedDate not supplied

Gonadal cysts in spotted gar (Lepisosteus oculatus) from Bayou Trepagnier, Louisiana, USA.

Gonadal cysts of spotted gar (Lepisosteus oculatus), an air-breathing teleost commonly found in Louisiana waters, are described. Fish were collected from two sites: Bayou Trepagnier, a petroleum-contaminated site (30 males and 42 females), and Bayou Traverse, a control site (17 males and 15 females). After fish were evaluated for gross abnormalities, they were necropsied and the gonads, gonadal ducts, and gonadal cysts were evaluated histologically. Multilocular fluid-filled cysts were noted in the testes, or spermatic ducts of four spotted gars from the Bayou Trepagnier. Unilateral ovarian cystadenomas were present in one female from Bayou Trepagnier. No cysts were observed in the gonads of spotted gar from the control site.

Animals↗
PubMedDate not supplied

Cadmium accumulation and effects on progesterone release by cultured human trophoblast cells.

This study was designed to examine the characteristics of cadmium bioaccumulation by human trophoblast cells in culture and the subsequent effect of cadmium exposure on progesterone production and syncytial formation. The accumulation of cadmium suggested a time- and dose-dependent relationship, although it was not significant. The rate of metal accumulation was similar in all cadmium-treated groups. After 72 h of continuous exposure to cadmium concentrations of 5, 10, and 20 microM, progesterone release was diminished to 69, 51, and 38% of control values (P < 0.05), respectively. When cells were exposed to cadmium from 72 to 96 h (after syncytial development), progesterone release exhibited the same pattern of decline in response to increasing cadmium concentrations. Histologic evaluation of whole mounts of trophoblast cells exposed to 20 microM CdCl2 for 96 h revealed that syncytial formation seemed to be uninhibited. The pattern of cadmium-accumulation by normal cultured human trophoblast cells suggests a time- and dose-relationship with a concomitant decrease in progesterone release that occurs without apparent inhibition of syncytial development.

Cadmium↗