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Biomedical subjects

M A Hansen

Publications and source records attributed to M A Hansen.

At least 55 records · Page 3Linked to original sources
PubMed1992

No secular increase in the prevalence of vertebral fractures due to postmenopausal osteoporosis.

We examined whether the prevalence of vertebral fractures in otherwise healthy, 70-year-old Danish women had increased during an interval of 10 years. The population-based epidemiological study included two age-matched groups of postmenopausal women. Group 1 consisted of 70-year-old women (n = 386) living in a defined area of suburban Copenhagen recruited in 1979 for an epidemiological study. Of the 285 women who were entered, 173 were judged healthy, without secondary causes of osteoporosis. Group 2 was recruited by sending questionnaires to all women aged 68-72 years living in the same area in 1989. Of the 512 women who attended a medical screening, 387 were found to be without secondary causes of osteoporosis and had a spinal radiograph. Radiographs of the thoracolumbar spine were assessed for vertebral fracture by five radiological methods. There was no significant difference between the two groups in the prevalence of vertebral fractures and the 95% confidence intervals overlapped completely in all methods. The prevalence rates varied by method from about 35% to more than 80% but the distribution of fracture types was similar in the two groups. We conclude that the prevalence of vertebral fractures due to postmenopausal osteoporosis has not increased since 1979 in otherwise healthy women residing in suburban Copenhagen, and that comparison of prevalences between studies requires that they use the same method of radiological assessment.

Aged↗
PubMed1991

Role of peak bone mass and bone loss in postmenopausal osteoporosis: 12 year study.

OBJECTIVE: To examine the role of peak bone mass and subsequent postmenopausal bone loss in the development of osteoporosis and the reliability of identifying women at risk from one bone mass measurement and one biochemical assessment of the future bone loss. DESIGN: Population based study. SETTING: Outpatient clinic for research into osteoporosis. SUBJECTS: 178 healthy early postmenopausal women who had participated in a two year study in 1977. 154 of the women underwent follow up examination in 1989, of whom 33 were excluded because of diseases or taking drugs known to affect calcium metabolism. MAIN OUTCOME MEASURES: Bone mineral content of the forearm and values of biochemical markers of bone turnover. RESULTS: The average reduction in bone mineral content during 1977-89 was 20%, but the fast losers had lost 10.0% more than had the slow loser group (mean loss 26.6% in fast losers and 16.6% in slow losers; p less than 0.001). Prediction of future bone mineral content using baseline bone mineral content and estimated rate of loss gave results almost identical with the actual bone mineral content measured in 1989. Seven women had had a Colles' fracture and 20 a spinal compression fracture. The group with Colles' fracture had low baseline bone mineral content (34.7 (95% confidence interval 31.3 to 38.1) units v 39.4 (38.1 to 40.8) units in women with no fracture) whereas the group with spinal fracture had a normal baseline bone mineral content (38.1 (35.0 to 41.1) units) but an increased rate of loss (-2.4 (-3.5 to -1.3)%/year v -1.8 (-2.1 to -1.5)%/year in women with no fracture). CONCLUSIONS: One baseline measurement of bone mass combined with a single estimation of the rate of bone loss can reliably identify the women at menopause who are at highest risk of developing osteoporosis later in life. The rate of loss may have an independent role in likelihood of vertebral fracture.

Age Factors↗
PubMed1991

Potential risk factors for development of postmenopausal osteoporosis--examined over a 12-year period.

In a longitudinal study, we investigated the influence of risk factors on bone mass at menopause and postmenopausal bone loss in 121 healthy postmenopausal women. These women had completed a 2-year prospective study in 1979 and a follow-up examination in 1989. Measurements of the bone mineral content in the distal forearm (single photon absorptiometry) were performed 9 times during the initial study and once at the follow-up examination. Bone mass at menopause (initial measurement), rate of early postmenopausal bone loss, and the subsequent rate of bone loss over 10 years were thus determined. In addition, the bone mineral density of the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometry (DXA) in 1989. Information about risk factors was assessed by standardized questionnaires and included reproductive history and lifestyle factors (intake of calcium and vitamin D supplements, consumption of alcohol and caffeine, smoking habits, and physical activity). Lactation, oral contraceptive use, and dietary calcium intake above 1500 mg per day was associated with significantly increased bone mass at menopause. The number of pregnancies reduced the rate of early postmenopausal bone loss, whereas moderate alcohol consumption reduced the subsequent rate of bone loss. Smoking significantly reduced femoral bone mineral density. In conclusion, the present prospective study showed that some of the examined putative risk factors positively influenced bone mass at menopause, especially calcium intake, whereas the postmenopausal bone loss was virtually unaffected. Assessment of risk factors in postmenopausal women thus seems to have limited value for reducing future risk of osteoporosis.

Aged↗
PubMed1991

Dose-response bioactivity and bioavailability of salmon calcitonin in premenopausal and postmenopausal women.

We investigated the acute, dose-response to three intranasal doses of salmon calcitonin (sCT) (50 IU, 100 IU, and 200 IU) and one im dose (50 IU) in eight premenopausal and eight early postmenopausal women. Total serum calcium and serum beta-endorphin revealed significant changes after all four administrations (P less than 0.05). After the two highest intranasal and the im doses cAMP increased 10% and 35%, respectively (P less than 0.05). All administrations except the 50 IU intranasal dose produced significant increases in plasma sCT (P less than 0.05). The areas under the concentration-time curves, calculated for the period with the maximal changes (i.e. 120-240 min), illustrated a significant dose-related response in total serum calcium, beta-endorphin, and sCT (P less than 0.01-0.001). cAMP showed a dose-related tendency, the response to the im injection being significantly higher than that to the two lowest doses of intranasal sCT (P less than 0.05). We conclude that the doses administered produce a dose-related biological response and bioavailability. In women with normal and high bone turnover, sCT 100 IU intranasally seems as optimal as 50 IU im. The response to sCT should, furthermore, be assessed on bioactivity rather than on bioavailability.

Administration, Intranasal↗
PubMed1990

Discontinuous calcitonin treatment of established osteoporosis--effects of withdrawal of treatment.

PURPOSE: The purpose of this study was to examine the effects of discontinuous treatments with intranasal salmon calcitonin on bone and calcium metabolism in postmenopausal women and to establish the effects of withdrawing treatment. PATIENTS AND METHODS: This report presents data from 26 postmenopausal women with established osteoporosis (forearm fracture) 12 months after withdrawal of a 1-year double-blind, placebo-controlled therapy with intranasal calcitonin. The women then resumed treatment with calcitonin 200 IU plus calcium 500 mg daily in an open design for an additional 1-year period. A control group of 19 age-matched women (no forearm fracture) did not receive any treatment. RESULTS: At the end of the 3 years, the control group had lost significantly more bone in the forearm (single photon absorptiometry) and spine (dual photon absorptiometry) than had the group treated with intranasal calcitonin for 2 years, whereas the group receiving calcitonin for 1 year had intermediate values. During the year of withdrawal, the rate of bone loss was similar in the women who had received calcitonin and those who had received placebo. Calcitonin was especially effective in women with initially high bone turnover and low bone mass. The bone response in the spine could, furthermore, be estimated by the changes in bone turnover. CONCLUSION: Discontinuous treatment with intranasal calcitonin affects bone and calcium metabolism in established osteoporosis. In women with high-turnover osteoporosis, therapy results in a net gain of bone in both the peripheral and axial skeleton. Response to treatment may be monitored by changes in bone turnover.

Absorptiometry, Photon↗
PubMed1990

Bone mass measured by photon absorptiometry: comparison of forearm, heel, and spine.

We assessed bone mass quantification at different skeletal sites by single and dual photon absorptiometric (SPA and DPA) methods. Improved DPA measurement of spinal bone mineral density in young healthy subjects showed a short- and long-term precision of 1.2% and 1.6%. Compared to the conventional DPA method the imprecision was reduced by more than 50%. The appendicular measurements were more precise (0.5-1.2%). We present the intercorrelations and predictive errors between peripheral measurements and improved spinal and total body bone measurements in early postmenopausal women (n = 144) recruited in 1988. To compare the improved system with the conventional methods, we retrieved data on age-matched early postmenopausal women (n = 151) recruited in 1983. In the 1988 population all peripheral methods had similar predictive errors in estimation of spinal bone mineral density (SEE = 11-13%) and total body bone mineral density (SEE = 4-5%). Measurement of trabecular bone in the heel and distal forearm did not improve the validity of predicting spinal bone mass. In a cadaver study (n = 11) the predictive error in estimation of the spinal ash weight from forearm measurements was of the same magnitude (15%) as that in estimation of the spinal BMC from the forearm (16%). We conclude that the predictive error in estimation of spinal bone mass from peripheral bone measurements is more likely to be caused by intra-skeletal variation in bone mass than by precision errors. However, this does not reflect the inability of peripheral bone mass measurements to predict fracture risk.

Absorptiometry, Photon↗
PubMed1990

Dual-energy x-ray absorptiometry: a precise method of measuring bone mineral density in the lumbar spine.

We compared two methods of measuring spinal bone mineral content and density (BMC/BMD): conventional dual-photon absorptiometry (DPA) and a more recent method, dual-energy x-ray absorptiometry (DEXA). The clinical usefulness of both methods was compared in the measurement of BMC in the forearm. DEXA had a long-term in vivo precision of 1% which was significantly better than that of DPA. Changes in the distribution of fatty tissue influenced the accuracy of the two spinal methods in different ways. Forearm BMC discriminated between the bone mass of early and late postmenopausal women to the same degree as DPA and DEXA. The variability in the response to estrogen treatment and placebo was much lower with DEXA and forearm BMC than with DPA. We conclude that DEXA provides a fast and precise measurement of spinal BMC/BMD. The accuracy remains to be evaluated for in vivo studies.

Absorptiometry, Photon↗
PubMed1989

Effect of salcatonin given intranasally on early postmenopausal bone loss.

OBJECTIVE: To study the effect of salmon calcitonin (salcatonin) given intranasally on calcium and bone metabolism in early postmenopausal women. DESIGN: Double blind, placebo controlled, randomised group comparison. SETTING: Outpatient clinic for research into osteoporosis. SUBJECTS: 52 Healthy women who had had a natural menopause two and a half to five years previously. INTERVENTIONS: The 52 women were allocated randomly to two years of treatment with either salcatonin 100IU given intranasally (n = 26) or placebo (n = 26). Both groups received a calcium supplement of 500 mg daily. Seven of the women receiving salcatonin and six of those receiving placebo left the study before its end. MAIN OUTCOME MEASURES: Bone mineral content in the spine, the total skeleton, and the forearms after two years of treatment. RESULTS: Bone mineral content in the spine was significantly higher in the women who had received salcatonin than in those who had received placebo both after one year and after two years of treatment. After one year the difference was 3.8% (95% confidence interval 0.0 to 7.6%) and after two years it was 8.2% (3.8 to 12.6%). In contrast, the bone mineral content in the distal and proximal forearms and in the total skeleton declined similarly in both groups by about 2% each year, and after two years of treatment the differences between the groups were not significant. Biochemical estimates of bone turnover were not affected by salcatonin. CONCLUSION: The results suggest that salcatonin given intranasally in the dose used prevents bone loss in the spine of early post menopausal women but does not affect the peripheral skeleton.

Administration, Intranasal↗
PubMed1982

Nutrition and immunity: the influence of diet on autoimmunity and the role of zinc in the immune response.

Nutrition exerts profound influence on immunological functions effecting both cell-mediated (humoral) and T cell-mediated (cellular) immune functions. Even the interaction of the immune systems can be profoundly influenced by restrictions or excesses of dietary constituents. In experimental systems where it is possible to control precisely the influence of specific nutriments, development and expression of autoimmune diseases and the associated immunodeficiencies of aging can be delayed by restrictions of dietary protein, protein and calories, fat, zinc, or even essential fatty acids. Tumor immunities likewise can be affected and sometimes even enhanced by restriction of protein, calories, or protein and calories, an influence associated with major delay in development of the experimental cancers--e.g. breast cancer. T cell-mediated immunodeficiencies associated with clinically apparent protein or protein calorie malnutrition are often attributable not to the major nutriment deficiencies per se but to accompanying zinc deficiency, a finding reflecting the vital role of zinc in many immunological functions. Dietary zinc deficiency appears to be responsible, at least in part, for the immunodeficiency that is so regularly associated with certain human cancers, such as epidermoid cancers of the head and neck region.

Animals↗
PubMed1980

Extraction and thin layer chromatographic confirmation of urine residues: new plate development.

AOAC method 44.146--44.148 (12th ed.) yielded incomplete separation of compounds recovered from urine residues. Problems with decomposition of standard compounds, loss of sample during extraction/concentration, and development of excessive background color during plate spraying were encountered. Modifications were made to deal with these problems as follows: Allantoin standard is now stored in 90% acetone, 30ml beakers are used instead of conical tubes during extraction, and smaller amounts of pDMAB are used during plate spraying. A collaborative study was conducted to compare sandwich chamber spot separation to larger tank separation. The study showed that total separation of all spots among all analysts was obtained with the sandwich chamber, whereas incomplete separation of spots was obtained with the tank. Also, standard deviation of spot Rf values was smaller with the sandwich chamber. The modified method has been adopted as official first action.

Animals↗
PubMed1979

An electromyographic and roentgen cephalometric study of occlusal morphofunctional disharmony in children.

In a sample of children with dual bite and symptoms in the masticatory system, the activity of the anterior temporal and masseter muscles was studied electromyographically during clench and light tapping in the posterior occlusal contact position and centric occlusion and in protrusive bite on the incisors. The findings indicated that the optimal muscle function during maximal clench and tapping with displayed in the posterior occlusal contact position, which in the present subjects was situated, on the average, 0.5 to 1 mm. anterior to the centric jaw relation. It should therefore be recommended that, in orthodontic treatment of children with dual bite, the intercuspal position (centric occlusion) should be established in the posterior occlusal relationship. This is in accordance with the opinion of several authors who have emphasized the use of the retruded contact position (the centric jaw relation) as key reference position in orthodontic treatment and occlusal rehabilitation. These authors have further emphasized the importance of stable occlusal contacts in centric relation, centric occlusion, and the various jaw excursions in obtaining and maintaining a harmonious function between the dentition, the temporomandibular joints, and the neuromuscular system.

Adolescent↗
PubMed1976

Nutritional deficiency, immunologic function, and disease.

Several experiments conducted by our group over a period of 6 years have shown that nutritional stress, especially protein and/or calorie deprivation, leads to many, often dramatic, changes in the immune responses of mice, rats, and guinea pigs. Chronic protein deprivation (CPD) has been shown to create an enhancing effect on the cell-mediated immune responses of these animals. Humoral responses under CPD conditions were most often found to be depressed, but sometimes were unaffected, depending on the nature of the antigen employed. Chronic protein deprivation, consistent with the pattern just mentioned, improved tumor immunity by depressing production of B-cell blocking factors, and, in at least one instance, resistance to development of mammary adenocarcinoma in C3H mice was associated with evidence of increased numbers of T suppressor cells. Profound nutritional deficits (less than 5% protein per total daily food intake) depressed both cellular and humoral immunity. Early, though temporary, protein deprivation caused a long-term depression of both cellular and humoral immunity also, with the humoral component being the first to recover. Manipulation of protein and calories was found to have a profound effect on certain autoimmune conditions. Diets high in fat and low in protein favored reproduction but shortened the life of NZB mice, whereas diets high in protein and low in fat inhibited development of autoimmunity and prolonged life. Chronic moderate protein restriction permitted NZB mice to maintain their normally waning immunologic functions much longer than mice fed a normal protein intake. Further, the low-protein diet was associated with a delay in development of manifestations of autoimmunity. Decreasing dietary calories by a reduction of fats, carbohydrates, and proteins more than doubled the average life span of (NZB X NZW)F1 mice, a strain prone to early death from autoimmune disease. Histopathologic studies using immunofluorescent microscopy revealed that the development of the renal lesions caused by the deposition of antigen-antibody complexes, which is so characteristic of these mice, was markedly delayed.

Anemia, Hemolytic↗