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Biomedical subjects

A Richards

Publications and source records attributed to A Richards.

At least 163 records · Page 9Linked to original sources
PubMed1981

Effect of intraperitoneally injected fluoride on plasma calcium in suckling and adult rats.

Sodium fluoride 10, 20 or 40 mg/kg body weight was given intraperitoneally to rats (6-11 days old and 90-95 days old). Blood analyses showed an initial increase in plasma fluoride concentration. The subsequent decrease in fluoride was paralleled by a decrease in total plasma calcium. These plasma concentrations were normal at blood collection 4 days after fluoride injection. The baby rats differed from the older rats in that their initial plasma calcium was higher and that the drop in plasma calcium concentration was less pronounced than in the old rats. A diet low in calcium and phosphate enhanced the effects of fluoride on total plasma calcium. The data indicate that the effect of large doses of fluoride on lowering the plasma calcium level is modified by the calcium intake.

Aging↗
PubMed1979

A longitudinal study of very low-birthweight infants. II: Results of controlled trial of intensive care and incidence of handicaps.

Between 1966 and 1970, infants with birthweights between 1000 and 1500g entered a randomized controlled trial to determine the short-term and long-term results of neonatal intensive care. Of 158 long-term survivors, five were lost to follow-up, but the multidisciplinary research team prospectively followed 143 children up to the age of eight years. Useful data were available for the other 10 children. Of the long-term survivors 74 had received routine, and 84 had received intensive nursery care. At eight years of age there were no statistically significant differences in the frequencies of a variety of individual abnormalities; fewer of the intensively managed children had cerebral palsy, but sensorineural deafness and ocular abnormalities occurred more frequently. Individual children were graded into four carefully defined groups: (a) profound handicap (4.4 per cent of entire study group); (b) severe handicap (10.1 per cent); (c) significant handicap (37.3 per cent); and (d) trivial or no handicap (41.8 per cent). Inadequate data were available for 6.3 per cent of the children. It was apparent that the improved survival attributed to intensive neonatal care was achieved at the expense of additional severely handicapped children, and this feature is discussed.

Cerebral Palsy↗
PubMed1976

Simultaneous production of negative and positive radiographic images.

A two-film radiographic procedure which simultaneously produces "white bone" and "black bone" images is described. The white bone image (the negative image) is a conventional radiograph. The black bone image (the positive image) would be used to print radiographic images on photographic paper. This technique should be limited to the examination of inanimate objects because of the large exposure that is necessary.

Radiography, Dental↗
PubMedDate not supplied

Malignant neuroendocrine tumor presenting in the mandible.

The carotid body, jugulotympanic, vagal, and laryngeal paragangliomas are the most common paragangliomas respectively within the head and neck, although unusual examples in other sites have been described. Among these are several references in the literature to a mandibular or "alveolar body" paraganglioma, even though such an entity does not appear to have been adequately documented. This report describes a case which presented as an extensive osteoblastic tumor involving the mandible and which radiographically appeared as a typical osteosarcoma. However, the immunohistochemical and electron microscopic features were of a neuroendocrine tumor and the histologic pattern suggested a paraganglioma. The tumor was nonfunctional and an extensive search failed to reveal any further lesions. Eight months after resection of the lesion, metastatic deposits appeared within the left iliac crest and lumbar vertebra. The origin of this tumor is discussed.

Aged↗
PubMedDate not supplied

Salivary antibody detection in epidemiological surveys: a pilot study after a mass vaccination campaign against rubella in São Paulo, Brazil.

The sensitivity and specificity of salivary rubella antibody detection was investigated using samples collected from 301 children after a mass vaccination campaign in the state of São Paulo, Brazil. Saliva samples were collected by 2 different methods: directly dribbling into a container or using a commercial collecting device. Corresponding finger-prick blood samples were collected on filter paper. Rubella specific immunoglobulin G (IgG) was measured in saliva by antibody capture radioimmunoassay and in blood samples by indirect enzyme-linked immunosorbent assay. The detection of salivary rubella specific IgG showed good correlation with the detection of rubella antibody in the blood samples. For both collecting techniques the predictive value for a positive saliva test was > 99% compared with the results from the blood tests. However, the predictive value for a negative saliva test was only 58.3% for a dribbled sample, compared to 100% for saliva collected using the commercial device. Moreover, collecting saliva by dribbling from children less than 4 years old was difficult. The detection of rubella specific IgG in saliva collected using a commercial device proved to be sensitive and specific in this epidemiological study, encouraging its more widespread application as a means of surveillance after mass vaccination.

Adolescent↗
PubMedDate not supplied

Marked decrease in trabecular bone quality after five years of sodium fluoride therapy--assessed by biomechanical testing of iliac crest bone biopsies in osteoporotic patients.

Sodium fluoride has for more than 2 decades been a commonly used therapeutic agent for established osteoporosis because of a repeatedly documented anabolic effect on trabecular bone mass. Recently, however, three controlled trials have failed to demonstrate any therapeutic advantage of NaF over placebo with respect to vertebral fracture rate. Also, there have been several reports of an increased incidence of nonvertebral fractures during fluoride administration. Thus, the efficacy of fluoride therapy remains a controversial issue. The aim of this longitudinal study was to investigate the effect of sodium fluoride (40-60 mg per day), calcium (45 mmol), and vitamin D2 (18,000 IU) on trabecular bone strength, assessed before and after 1 or 5 years of treatment for osteoporosis. Iliac crest biopsies were taken before and after 1 year of treatment in 12 patients, and before and after 5 years of treatment in 14 patients. Measurements were made of biomechanical competence, ash content, and bone fluoride content, and bone strength parameters were normalized for ash content, thereby obtaining a measure of trabecular bone quality. Bone fluoride content was significantly increased after both 1 and 5 years of treatment, indicating that the administered fluoride had been ingested. After 1 year of treatment, no difference was observed in iliac crest trabecular bone ash content. A general trend for decreased bone strength and bone quality was observed, but this was insignificant. After 5 years of fluoride treatment, an insignificant decrease in iliac crest trabecular bone ash content was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMedDate not supplied

Normal age-related changes in fluoride content of vertebral trabecular bone--relation to bone quality.

In several clinical osteoporosis studies, fluoride treatment has been shown to have a positive effect on bone mass but without a concomitant decrease in vertebral fracture rate. In contrast, some studies have shown that increases in spinal BMD are also paralleled by decreased vertebral fracture incidence. We have previously demonstrated, in a pig model, that 6-month treatment with fluoride increased bone mass but decreased bone quality. The aim of the present study was to elucidate whether normal age-related fluoride accumulation in human bone per se influences bone quality. From 73 normal individuals, aged 20-91 years (36 females, 37 males) two trabecular bone cylinders were obtained from the central part of L3. Biomechanical competence, ash density, and fluoride content were assessed in one cylinder, and trabecular bone volume was determined in the other. The results showed an age-related decrease in bone mass for both men and women. Bone strength normalized for bone mass (bone quality also identical with bone material strength) also showed an age-related decrease in men and women. Bone fluoride concentration increased significantly in both sexes (range 463-4000 ppm). Multiple regression analyses disclosed that fluoride by itself had no influence on bone quality, in this study with a limited number of cases, when the influence of sex and age were taken into account. It is concluded that normal age-related accumulation of fluoride in vertebral trabecular bone does not seem to affect the quality of bone. Whether this is also the case during fluoride therapy has to be assessed.

Adult↗