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Biomedical subjects

A Webb

Publications and source records attributed to A Webb.

125 records · Page 7Linked to original sources
PubMed1985

Microcrystalline hydroxyapatite compound in prevention of bone loss in corticosteroid-treated patients with chronic active hepatitis.

To determine whether microcrystalline hydroxyapatite compound (MCHC) could reduce bone loss or its consequences in patients with chronic active hepatitis (CAH) on corticosteroid therapy, a controlled trial was conducted in 36 such patients over a period of 2 years. Both skeletal symptoms (back pain) and fractures were uncommon during the trial period but both showed non-significant differences in favour of the MCHC group and biochemical investigations were suggestive of a reduction in parathyroid over-activity. Continued reduction in bone mineral content of the radius (photon absorptiometry) was halted in those receiving MCHC and iliac crest bone biopsy showed a non-significant increase in trabecular bone volume. The fall in iliac crest cortical plate thickness was significantly less (P less than 0.025) in the MCHC group and the results overall were consistent with a beneficial effect from MCHC in corticosteroid-induced osteoporosis.

Adult↗
PubMed1983

Computed tomographic and nuclear magnetic resonance correlation of canine ceroid-lipofuscinosis with aging.

Canine ceroid lipofuscinosis is a degenerative neuronal disorder which has as a distinct pathologic counterpart, neuronal ceroid lipofuscinosis or Batten's disease in humans. The disease occurs in English setters and is associated with abnormal accumulation of autofluorescent lipopigments. As such, a study of this animal model may allow insight into the aging process as well. This investigation explores the computed tomographic features of canine ceroid-lipofuscinosis and correlates these findings (progressive atrophy, inherent changes in CT/NMR tissue characteristics) with clinical and pathologic features.

Animals↗
PubMed1982

Histomorphometric analysis of bone biopsies from the iliac crest of normal British subjects.

Bone histomorphometric parameters have been measured in a group of normal British subjects of both sexes over a wide age range. There is loss of trabecular mineralized bone volume with advancing age and an increase in osteoid volume and in the trabecular bone surface covered by osteoid seams. There was no change in the mineral appositional rate or in bone resorption surfaces.

Adolescent↗
PubMed1981

Physical and hormonal evaluation of transsexual patients during hormonal therapy.

The optimal hormonal therapy for transsexual patients is not known. The physical and hormonal characteristics of 38 noncastrate male-to-female transsexuals and 14 noncastrate female-to-male transsexuals have been measured before and/or during therapy with various forms and dosages of hormonal therapy. All patients were hormonally and physically normal prior to therapy. Ethinyl estradiol was superior to conjugated estrogen in suppression of testosterone and gonadotropins but equal in effecting breast growth. The changes in physical and hormonal characteristics were the same for 0.1 mg/d and 0.5 mg/d of ethinyl estradiol. The female-to-male transsexuals were well managed with a dose of intramuscular testosterone cypionate of 400 mg/month, usually given 200 mg every two weeks. The maximal clitoral length reached was usually 4 cm. Higher doses of testosterone did not further increase clitoral length or suppression of gonadotropins; lower doses did not suppress the gonadotropins. Based on the information found in this study, we recommend 0.1 mg/d of ethinyl estradiol for the noncastrate male-to-female transsexual and 200 mg of intramuscular testosterone cypionate every two weeks for the noncastrate female-to-male transsexual.

Adolescent↗
PubMed1981

Vitamin D status and bone histomorphometry in gross obesity.

Plasma 25-hydroxyvitamin D concentrations and bone histomorphometry were investigated in 24 grossly obese subjects. The mean plasma 25OHD concentration was significantly lower in the obese group than in age-matched, healthy controls. Subnormal values were found in four obese subjects and in a further two subjects, who were investigated at the end of the summer, plasma 25-hydroxyvitamin D levels were at the lower end of the normal winter range. Bone histology was abnormal in two patients. In one, mild osteomalacia and secondary hyperparathyroidism were present while in the other patient the appearance suggested increased bone turnover, possibly as a result of healing osteomalacia. We conclude that gross obesity is associated with an increased risk of vitamin D deficiency, probably because of reduced exposure to uv radiation. Histological evidence of metabolic bone disease may also occur. Preoperative vitamin D deficiency may contribute in some patients to the development of metabolic bone disease after intestinal bypass.

Adult↗
PubMedDate not supplied

Low bone turnover state in primary biliary cirrhosis.

To determine whether bone loss in patients with chronic cholestatic liver disease is the consequence of a high or low bone turnover state, 30 female patients with biopsy-proven primary biliary cirrhosis underwent iliac crest biopsy following double tetracycline labeling. The mean trabecular bone volume was decreased as a result of trabecular plate thinning in both the premenopausal (p less than 0.02) and postmenopausal (p less than 0.05) patients, compared to age- and sex-matched controls. Indications that osteoblastic function was impaired included a significantly lower mean wall thickness (p less than 0.01) and mean osteoid seam width (p less than 0.05), and this in association with a decreased mineral appositional rate and prolonged mineralization lag time was suggestive of a defect in matrix synthesis. Further evidence of impaired osteoblastic activity was the significantly lower bone formation rate at both tissue (p less than 0.001) and basic multicellular unit levels (p less than 0.05) in the postmenopausal patients. Total resorption surfaces and fasting urinary calcium/creatinine ratios were significantly increased (p less than 0.005 and 0.05, respectively) in the premenopausal patients and mean interstitial bone thickness reduced in both pre- and postmenopausal patients, suggesting that increased resorption may also contribute to bone loss in primary biliary cirrhosis.

Adult↗
PubMedDate not supplied

Application of reduced-encoding imaging with generalized-series reconstruction (RIGR) in dynamic MR imaging.

Dynamic MRI has proven to be an important tool in studies of transient physiologic changes in animals and humans. High sensitivity and temporal resolution in such measurements are critical for accurate estimation of dynamic information. Fast imaging, often involving expensive hardware, has evolved for use in such cases. We demonstrate herein the possibility of accelerated data acquisition schemes on conventional machines using standard pulse sequences for dynamic studies. This is achieved by combining reduced-encoded dynamic data (typically 30 to 40 phase encodings) with a priori high-resolution data via a novel constrained image reconstruction algorithm. Such an approach reduces image acquisition time significantly (by a factor of 3 to 4 in the examples described here) without loss in the accuracy of information.

Animals↗
PubMedDate not supplied

Histomorphometric analysis of dynamic parameters of trabecular bone formation in the iliac crest of normal British subjects.

Some dynamic parameters of bone formation in trabecular iliac crest bone have been measured in a group of normal British subjects of both sexes over a wide age range. There was a significant age-related decrease in mean wall thickness. When either double plus single or double only tetracycline-labeled surfaces were used to represent actively mineralizing surfaces, there was a significant age-related decrease in the bone formation rate at the basic multicellular unit level. Osteoid maturation period showed a significant age-related increase when calculated using double plus single labeled surfaces. There was no significant change with age in fractional labeled surfaces, mean osteoid seam width, bone formation rate at tissue level, or bone formation period. The mean osteoid seam width and osteoid maturation period were significantly higher in males than in females.

Adult↗