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Biomedical subjects

R Lindsay

Publications and source records attributed to R Lindsay.

At least 199 records · Page 11Linked to original sources
PubMed1986

Organon OD 14 (tibolone) and menopausal dynamic hormone profiles.

Hormonal profiles were studied in 15 post-menopausal women, 7 of whom had been treated with Organon OD 14 (Tibolone) and 8 with placebo tablets for 3 yr. In the Tibolone-treated group, the sex hormone binding globulin (SHBG) levels were significantly lower, while the estimated free testosterone levels, the testosterone/SHBG ratio and the thyroid-stimulating hormone (TSH) response to thyrotrophin-releasing hormone (TRH) were significantly higher than in the placebo group. Prolactin and triiodothyronine (T3) concentrations were lower in the actively treated group, although the differences were not statistically significant. No significant differences were observed with respect to thyroxine (T4), TSH, basal cortisol or cortisol response to synacthen.

Anabolic Agents↗
PubMed1986

Serum vitamin D2 and vitamin D3 metabolite concentrations and absorption of vitamin D2 in elderly subjects.

The serum vitamin D2 and vitamin D3 metabolite concentrations and intestinal absorption of vitamin D2 were determined in healthy ambulatory and chronically institutionalized elderly subjects with normal renal function. The 25-hydroxyvitamin D (25OHD) concentrations were normal in all subjects (range, 8-43 ng/ml), although institutionalized subjects had a significantly lower mean value [19.2 +/- 2 (+/- SEM) ng/ml; P less than 0.01] compared with ambulatory subjects (25.3 +/- 2 ng/ml). All but one ambulatory subject had 25OHD3 as the major circulating form, whereas 25OHD2 was the major circulating metabolite in one third of the institutionalized subjects. The mean 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentration in both groups was normal, but nine subjects had levels at or below the lower limit of normal despite normal 25OHD concentrations. Separate assay of 1,25-(OH)2D2 and 1,25(OH)2D3 revealed proportional distributions similar to those for 25OHD2 and 25OHD3. To study the effect of age on the intestinal absorption of vitamin D, we compared serum vitamin D2 concentrations after oral administration of 50,000 IU vitamin D2 in both healthy vitamin D-sufficient elderly subjects and young adults. We found no evidence of malabsorption of vitamin D in the elderly subjects. In summary, elderly subjects in New York, whether institutionalized or not, have normal serum 25OHD concentrations. However, while most elderly subjects have normal serum 1,25-(OH)2D levels, a significant proportion fail to produce normal concentrations of 1,25-(OH)2D, possibly due to age-related disturbances in renal synthesis of the hormone.

25-Hydroxyvitamin D 2↗
PubMed1986

Is reactive gliosis a property of a distinct subpopulation of astrocytes?

We have shown previously that the A2B5 monoclonal antibody distinguishes two types of glial fibrillary acidic protein-containing astrocytes in semithin frozen sections of adult rat optic nerve: A2B5- (type-1) astrocytes are found mainly at the periphery of the nerve, where they form the glial limiting membrane, while A2B5+ (type-2) astrocytes are found mainly in the interior of the nerve and constitute more than 65% of the astrocytes in the adult optic nerve. In the present study we show that although most astrocytes in semithin frozen sections of adult rat corpus callosum and optic nerve are A2B5+, the great majority of reactive astrocytes in similar sections of corpus callosum examined 20 weeks after a stab lesion, and in optic nerve examined 20 weeks after adult transection, are A2B5-. Although both A2B5+ and A2B5- astrocytes are stimulated to synthesize DNA in the first week after transection, adult optic nerves examined 20 weeks after transection contain only half as many astrocytes as do normal optic nerves: While A2B5+ astrocytes are reduced almost 10-fold, A2B5- astrocytes are increased by about 25%. We consider the simplest interpretation of these findings to be that type-1 astrocytes are largely responsible for forming glial scars in adult white matter following either a stab lesion or Wallerian degeneration and that in transected optic nerves, most type-2 astrocytes eventually die, possibly because they depend on axons for their long-term survival.

Animals↗
PubMed1985

Effect of long term hormone replacement on plasma prolactin concentrations in women after oophorectomy.

Plasma prolactin concentrations were studied in 88 oophorectomised women who had been receiving mestranol or placebo for three to 11 years. Thirty one of them were also studied under basal conditions and by tests with thyrotrophin releasing hormone. Under basal conditions the mean prolactin concentration was higher in the oestrogen treated group but under non-rested, clinic conditions the difference was lost because of a rise in prolactin value in the placebo group only. Hence the groups showed a different prolactin response to the mild stress of clinic attendance but the same proportionate responsiveness to thyrotrophin releasing hormone. The data suggest that long term hormone replacement has no significant effect on circulating prolactin concentrations under non-rested, everyday conditions and that the prolactin stimulating effects of minor stress and oestrogen may share a similar mechanism.

Aged↗
PubMed1985

Dual-photon Gd-153 absorptiometry of bone.

Dual-photon absorptiometry with gadolinium 153 was used to measure the mineral content of lumbar vertebrae in cadavers, excised vertebrae with marrow, and dry, marrow-free vertebrae. The error introduced by the surrounding soft tissue of cadavers was 3%, and the error in determining mineral mass or density in excised vertebrae was about 5%. The correlation coefficient between the results of Gd-153 and corrected iodine 125 (single-photon) absorptiometry on 24 femoral necks was 0.99, and the predictive error was 3.7%. Dual-photon absorptiometry accurately indicates bone mass and bone density and is only slightly affected by either surrounding tissue or fat changes in bone marrow.

Bone Marrow↗
PubMed1985

Prevention of bone mineral loss in postmenopausal women by norethisterone.

The effect of norethisterone on bone mineral metabolism was examined in 43 postmenopausal women. A significant decline in serum calcium, phosphate, and alkaline phosphatase in urinary calcium/creatinine ratio and in tubular maximum reabsorption of phosphate was demonstrated. There was no alteration in urinary hydroxyproline/creatinine ratio. The bone mineral content measured over two years by single photon absorptiometry was compared in 20 patients receiving norethisterone and a matched control group receiving placebo. There was significant protection against bone loss in the norethisterone group.

Alkaline Phosphatase↗
PubMed1984

Lipoprotein levels during hormone replacement therapy by vaginal ring pessaries.

Nineteen women who had had a surgical menopause had a vaginal ring pessary containing levonorgestrel and oestradiol in situ for a period of 3 months. Fasting lipoprotein levels were measured before, and after 1 and 3 months on therapy. After 3 months total triglyceride levels were significantly lower than baseline values (P less than 0.01) as were very-low-density-lipoprotein cholesterol (P less than 0.01), low-density-lipoprotein cholesterol (P less than 0.05) and high-density-lipoprotein cholesterol (P less than 0.001) levels. These changes suggest that in this preparation the effects of the progestogen component are dominant.

Adult↗
PubMed1984

The minimum effective dose of estrogen for prevention of postmenopausal bone loss.

In a controlled single blind study to determine the minimal effective dose of estrogen for protection against bone loss, conjugated equine estrogens in doses of 0.625 and 1.25 mg per day were equally effective in reducing bone loss in postmenopausal and oophorectomized women when bone mass was estimated by single-photon absorptiometry or radiogrammetry . Daily dose levels of less than 0.625 mg were essentially ineffective. Fifty percent response level was calculated to be 0.45 mg per day. Concomitant biochemical effects, reduction in urine calcium and hydroxyproline, were compatible with the observed effects on bone mineral.

Bone Resorption↗
PubMed1983

Two types of astrocytes in cultures of developing rat white matter: differences in morphology, surface gangliosides, and growth characteristics.

Two types of glial fibrillary acidic protein-positive (GFAP+) astrocytes were found in cultures of developing rat optic nerve. Type 1 astrocytes had a fibroblast-like morphology, did not bind tetanus toxin or the monoclonal antibody A2B5 (both of which bind to specific polysialogangliosides), and were stimulated to divide by an extract of bovine pituitary and by epidermal growth factor (EGF). Type 2 astrocytes had a neuron-like morphology, bound tetanus toxin and A2B5 antibody, and were not stimulated to divide by bovine pituitary extract or by EGF. Although both types of astrocytes were present in cultures of white matter, only type 1 astrocytes were found in cultures of gray matter. Astrocytes did not convert from one type to the other in culture: while many type 1 astrocytes adopted a neuron-like morphology when exposed to dibutyryl cyclic adenosine 3':5'-monophosphate, or pituitary or brain extracts, especially in serum-free medium, such morphologically altered cells did not bind tetanus toxin or A2B5 antibody. Although small numbers of tetanus toxin-binding, A2B5+, GFAP+ cells were present in suspensions of freshly dissected, neonatal optic nerves, most of the type 2 astrocytes in cultures of such optic nerves developed from tetanus toxin-binding, A2B5+, GFAP- cells, which were induced to express GFAP by the culture conditions. Since type 2 astrocytes have a neuron-like morphology and bind tetanus toxin and A2B5 antibody, these ligands cannot be used on their own as neuron-specific markers in central nervous system cultures.

Animals↗
PubMed1981

Assessment of synthetic steroid (Org OD 14): effect on skeletal metabolism by 24-h whole-body retention of diphosphonate.

Using a 24-h whole-body retention (WBR) of Tc99m hydroxyethylidene diphosphonate (HEDP), a sensitive measure of skeletal metabolism, 24 women receiving the synthetic steroid hormone Org OD 14 were studied. OD 14 was found to have a powerful suppressive effect on skeletal metabolism in both oophorectomized and non-oophorectomized women when compared with control subjects (P less than 0.001 and P less than 0.01, respectively). The degree of suppression was similar to that found with oestrogen therapy. While it has previously been shown that OD 14 prevents bone mineral loss (as measured by photon-absorptiometry), the present study provides further evidence as to the efficacy of this compound in suppressing skeletal metabolism.

Alkaline Phosphatase↗
PubMed1981

Oral complaints related to climacteric symptoms in oöphorectomized women.

Numerous oral complaints have been attributed to the female climacteric including altered taste, a burning sensation and xerostomia. However, the data relating these symptoms to the climacteric require elucidation as there have been no adequately controlled studies. In the present investigation, a group of 145 oöphorectomized women were followed for one year. Approximately half were treated with oestrogen replacement and the remainder with a placebo. The results indicate that the hormone had no direct effect upon the oral symptoms but that there was a general increase in somatic complaints which appeared to be related to the degree of neurosis experienced. This is turn can be attributed to vasomotor changes which are under the control of oestrogen.

Adult↗
PubMed1980

Prevention of spinal osteoporosis in oophorectomised women.

100 women who had taken part in a prospective controlled trial of oestrogen therapy for prevention of post-oophorectomy bone loss were reviewed after a median follow-up period of nine years. A significant reduction in height occurred among the placebo-treated group, but not in the group treated with mestranol (mean 23 x 3 micrograms/day). The placebo-treated group had a higher spine score, lower central vertebral height, and larger wedge-angle than the oestrogen group. Within each group none of these spinal morphometric changes correlated with changes in mineral content of metacarpal or radial bones as measured by photon absorptiometry or X-ray densitometry, although both peripheral and central measurements showed highly significant differences between groups. Oestrogen treatment, therefore, prevents against central, as well as peripheral, bone loss, and reduces the incidence of vertebral compression.

Body Height↗
PubMed1980

Skeletal uptake of diphosphonate. Method for prediction of post-menopausal osteoporosis.

24-h whole-body retention (WBR) of diphosphonate (a sensitive indicator of skeletal metabolism) was measured in 37 oophorectomised women. 14 women had been prescribed oestrogen supplements and 3 of these had defaulted from therapy. For the study group there was a significant correlation between WBR and both the rate of bone loss as measured by photonabsorptiometry (r = 0.7, p ¿ 0.001) and urinary hydroxyproline (r = 0.53, p < 0.001). The oestrogen-treated group had significantly lower values for WBR and rate of bone loss than the untreated group (p < 0.01, p < 0.01 respectively) indicating suppressed skeletal metabolism. However, the highest values were found in those who had defaulted from oestrogen therapy suggesting a rebound period of accelerated skeletal metabolism and bone loss. There was a significant negative correlation between WBR and oestrogen dosage (r = 0.75, p < 0.02) suggesting that it may be possible to adjust the dosage for optimal skeletal metabolic activity. WBR of diphosphonate provides a simple and sensitive measure of skeletal metabolism which correlates well with conventional measurements of bone loss. WBR may be useful in the screening and identification of women who have increased bone turnover just after the menopause and who may subsequently be at risk of osteoporosis developing.

Aged↗