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Biomedical subjects

C Christiansen

Publications and source records attributed to C Christiansen.

At least 235 records · Page 13Linked to original sources
PubMed1993

Possible variation in bone resorption during the normal menstrual cycle.

In order to determine whether bone turnover varies during the normal menstrual cycle, we measured biochemical markers of bone resorption (serum pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (sICTP), fasting urinary hydroxyproline/creatinine, fasting urinary pyridinoline/creatinine and fasting urinary deoxypyridinoline/creatinine) and bone formation (plasma osteocalcin, serum carboxy-terminal propeptide of type I procollagen and serum alkaline phosphatase) in ten healthy premenopausal women every two or three days for a complete menstrual cycle. A cyclic pattern was detected in sICTP, with its nadir during the follicular phase and its peak during the luteal phase, and an overall variation of 17% during the menstrual cycle (p = 0.004). No cyclic changes were observed in the urinary parameters of bone resorption or in the biochemical markers of bone formation. We conclude that sICTP, a new biochemical marker of bone resorption, undergoes small variations during a normal menstrual cycle in premenopausal women, whereas the biochemical markers of bone formation remain constant.

Adult↗
PubMed1993

Effect of meal frequency on blood glucose, insulin, and free fatty acids in NIDDM subjects.

OBJECTIVE: We studied the effects of meal frequency on blood glucose, serum insulin, and FFAs in 12 NIDDM subjects. RESEARCH DESIGN AND METHODS: Subjects were assigned in random order to two 8-hr observation periods after an overnight fast. They received isocaloric diets with similar composition either as six small or as two large meals. At the end of each study period, an IVGTT was given. RESULTS: Two large meals induced an 84% greater maximum amplitude of glucose excursions than six small meals (6.1 +/- 0.5 vs. 3.3 +/- 0.5 mM, P < 0.005) and higher insulin responses (P < 0.03). The Kg response to an IVGTT did not differ in the two situations. The average FFA level was lowest in response to frequent meals (P < 0.02). CONCLUSIONS: A higher meal frequency acutely subdues glucose excursions and reduces insulin and FFA levels during the daytime in older NIDDM subjects.

Blood Glucose↗
PubMed1993

Continuing challenges of functional assessment in rehabilitation: recommended changes.

Many innovative developments are under way to meet the challenges related to appropriate, valid, and practical functional assessment in occupational therapy. There is increasing agreement that occupational therapy's unique contribution to function is through its emphasis on occupational performance. There is also recognition, although limited, that assessing function without regard to the patient's life tasks and roles has serious shortcomings. If we accept that decisions related to intervention and program evaluation are only as good as the information on which they are based, our only option in the face of recognized shortcomings is to dedicate our efforts to develop improved strategies.

Activities of Daily Living↗
PubMed1993

Acute effects of graded alcohol intake on glucose, insulin and free fatty acid levels in non-insulin-dependent diabetic subjects.

Alcohol-induced hypoglycaemia is a well-known phenomenon in insulin-treated diabetic subjects. Less attention has been paid to the impact of alcohol on blood glucose and insulin responses in non-insulin dependent diabetic subjects. The aim of this study was to investigate the acute metabolic effects of different alcohol contents added to a non-alcohol beer in 10 non-insulin-dependent diabetes mellitus (NIDDM) subjects. The patients received 500 ml non-alcohol beer with an alcohol percentage (v/v) of 0 (A), 2.7 (B), and 5.4 (C), implying identical contents of ingredients except for alcohol. Blood glucose (mean +/- SE) responses were similar in the three situations (395 +/- 59, 365 +/- 86 and 261 +/- 26 mmol/l x 240 min). In contrast, the incremental insulin response areas increased dose dependently to alcohol (5430 +/- 1158, 9336 +/- 2172 and 12336 +/- 2922 pmol/l x 240 min) and showed a linear correlation (r = 0.39; P < 0.03). The average suppression of serum free fatty acid was similar in the three situations (72.4 +/- 4.4%, 76.3 +/- 6.0% and 68.2 +/- 6.3%). In conclusion, intake of small amounts of alcohol does not acutely deteriorate the glycaemic control in NIDDM. The fact that alcohol results in a dose-related elevation in insulin levels with unaltered blood glucose and free fatty acid responses in NIDDM points to an aggravation of insulin resistance.

Aged↗
PubMed1993

Epidemiology, biochemistry and some results with treatment of postmenopausal osteoporosis.

The present chapter deals with postmenopausal osteoporosis. This is an important disease because it affects millions of people throughout the world. The most serious of the osteoporotic fractures, the hip fractures, needs hospitalization, causes a high degree of mortality, and results often in dependent people. Osteoporosis is thus a significant socioeconomic burden. At the menopause bone turnover increases and bone loss accelerates. Postmenopausal bone loss and osteoporosis may be prevented by oestrogen replacement therapy, but convincing therapy for established osteoporosis does not yet exist. Anabolic steroid therapy can, however, increase the bone mineral content a few percentages a year in postmenopausal osteoporotic women.

Aged↗
PubMed1993

Biochemical characterization of air-filled albumin microspheres.

Heating and sonication of a solution of human serum albumin (HSA) yields air-filled microspheres that can be used as a contrast agent in ultrasound examinations. The microspheres are stabilized by a thin-layer of protein surrounding the air bubbles. As long as the microspheres were intact, the protein was insoluble in aqueous solutions. After disintegration of the microspheres, the protein could be solubilized in several solutions. The intermolecular interactions in the microsphere protein have been elucidated from its solubility properties. The microspheres were disintegrated by several detergents which also solubilized the protein. After pressure disintegration of the microspheres, the protein was solubilized immediately in urea and guanidinium chloride, and also in phosphate-buffered saline after incubation overnight. These results indicate that the protein was mainly stabilized by non-covalent forces. The solubilization in buffer was inhibited by a high salt concentration, suggesting that hydrophobic interactions were involved in stabilizing the microsphere structure. Analysis of the solubilized protein by gel filtration showed that the protein contained substantial amounts of soluble aggregates of HSA. Reduction of the disulphide bonds dissolved these aggregates into monomeric HSA, showing that intermolecular disulphide bonds were also involved in stabilization of the microspheres. The solubilized protein also contained less fatty acids than the soluble HSA used for the production of microspheres. These results show that the microsphere protein has the same characteristics as heat-denatured HSA.

Air↗
PubMed1993

Measurement of abdominal and intra-abdominal fat in postmenopausal women by dual energy X-ray absorptiometry and anthropometry: comparison with computerized tomography.

The aim was to develop a model for prediction of intraabdominal adipose tissue (AT) with combined dual energy X-ray absorptiometry (DXA) and anthropometry in postmenopausal women. Intra-abdominal and subcutaneous AT from the 1st to the 4th lumbar intervertebral disk was measured by computerized tomography (CT) (as a reference method) in 25 postmenopausal women (BMI 19.9-35.1 kg/m2). Fat was measured in the corresponding region by DXA. Abdominal sagittal diameters, skinfold thicknesses, and circumferences were also measured. Measurements of abdominal fat by CT and DXA were valid (r = 0.9, s.e.e.%: 7%). Measurement of abdominal fat by DXA explained about 80% of the variation in the intra-abdominal AT (by CT), whereas the waist to hip ratio was the only variable that correlated significantly with the intra-abdominal to subcutaneous AT ratio. Abdominal fat measured by DXA, the waist to hip ratio, and the sum of trunk skinfold thicknesses could in combination accurately predict the intra-abdominal AT measured by CT (r2 = 0.91, s.e.e.% = 15%). The sagittal diameter, measured either anthropometrically or by CT, was not a superior predictor of the intra-abdominal AT. We conclude that the intra-abdominal AT can be predicted in postmenopausal women by DXA combined with anthropometry.

Abdomen↗
PubMed1993

Relationships and independence of body composition, sex hormones, fat distribution and other cardiovascular risk factors in overweight postmenopausal women.

The relationships and independence of body composition, sex hormones, fat distribution and other cardiovascular risk factors were studied in 121 overweight postmenopausal women. Body composition and fat distribution were directly measured by dual energy X-ray absorptiometry (DXA); other parameters were waist-to-hip ratio (WTH), sex hormone binding globulin (SHBG), testosterone, androstenedione (A), oestradiol (E2), and lipids and lipoproteins; cigarette and alcohol consumption were recorded. SHBG was correlated with the fat distribution by DXA and WTH (r = -0.35, P < 0.01) and A with the fat mass (r = -0.3, P < 0.01). SHBG had a negative and alcohol and cigarette consumption a positive, independent relationship to a central fat distribution (by DXA and WTH, respectively) (P < 0.01). SHBG (r = 0.23, P < 0.05), fat distribution (WTH) and A (r = -0.2 to -0.3, P < 0.01) were correlated with high density lipoprotein cholesterol (HDL-C). However, only fat distribution (WTH) and A were independently related to HDL-C (P < 0.05). Fat distribution (WTH) and SHBG were independently related to triglycerides (P < 0.05), whereas fat distribution (by DXA) and E2 were independently associated with total cholesterol and low density lipoprotein cholesterol (LDL-C) (P < 0.05). Thus, in overweight postmenopausal women, androgenicity and cigarette and alcohol consumption were independently positively related to a central fat distribution. Furthermore, atherogenic levels of lipids and lipoproteins were independently related to a central fat distribution, androgenicity and low levels of oestrogens.

Absorptiometry, Photon↗
PubMed1993

Role of cigarette smoking on the postmenopausal endometrium during sequential estrogen and progestogen therapy.

OBJECTIVE: To study the effect of cigarette smoking on the endometrial response to sequentially combined hormone replacement therapy. METHODS: Healthy, early postmenopausal women were randomly assigned to three treatment groups: estradiol (E2) sequentially combined with 75 micrograms of levonorgestrel (19), or 150 micrograms of desogestrel (20), or 10 mg of medroxyprogesterone acetate (18). After 2 years of therapy, the hormone effects on the endometrium were assessed by endometrial histology; effects were also analyzed on biochemical markers of secretion, specifically, secretory endometrial protein (placental protein 14) in serum, and E2 dehydrogenase and isocitrate dehydrogenase in endometrial tissue. Information on smoking habits was elicited by questionnaire. RESULTS: Smokers numbered relatively more women with an atrophic endometrium (50 versus 22%) and proportionally fewer with secretory endometrium (50 versus 78%) (P < .05). The level of serum placental protein 14 was correspondingly almost halved in the smokers (P < .001). The influence of smoking was in part caused by a reduced level of serum E2, but primarily by a non-E2-mediated effect. The E2 effect accounted for 38% of the decrease in serum placental protein 14, and the non-E2-mediated smoking effect for 62%. Endometrial E2 and isocitrate dehydrogenase tended to be lower in smokers, but not after adjustment for the reduced serum E2 level. CONCLUSION: We suggest that smokers may benefit from a hormone combination with a higher dose of E2, even higher than expected as seen from the measurement of serum E2.

Desogestrel↗
PubMed1993

Prevention and treatment of osteoporosis with hormone replacement therapy.

Osteoporosis is characterized by decreased bone mass and increased susceptibility to fractures. The clinical consequences of osteoporosis are fracture, most commonly seen at the wrist, the spine and the hip. The prevalence of osteoporotic fracture is extremely high, with almost 50 percent of 70-year-old women having had at least one osteoporotic fracture. The prevalence in men is lower but may constitute a larger problem than expected. Osteoporotic fracture is therefore a significant cause of morbidity and mortality and represents a major problem of health care. Bone is the site of substantial metabolic exchanges, with bone resorption and formation continuing throughout life. The turnover processes are carried out by osteoclasts and osteoblasts in specialized cellular units. After cessation of growth, the skeleton probably consolidates to reach the peak bone mass at the age of 35-40 years. The relatively slow subsequent age-related bone loss occurs in both men and women, but women are additionally exposed to accelerated bone losses after the menopause. Oestrogen deficiency is the dominating pathogenetic factor for osteoporosis in women and is the drug of choice for prevention and treatment. Today it is established that hormone replacement therapy (HRT), using estrogen alone or estrogen plus a progestogen, can prevent osteoporosis in postmenopausal women. The greatest benefit from HRT is obtained if instituted shortly after menopause. However, the literature contains clear evidence that HRT prevents the bone loss in all stages of the postmenopausal life. A recent study of hormone replacement therapy of women with symptomatic osteoporosis has furthermore demonstrated that the incidence of fractures was significantly reduced during therapy.

Adult↗
PubMed1992

Effect of salcatonin given intranasally on bone mass and fracture rates in established osteoporosis: a dose-response study.

OBJECTIVE: To study the dose related response of salmon calcitonin (salcatonin) given intranasally on bone mass and bone turnover and the effect of salcatonin on rates of fracture in elderly women with moderate osteoporosis. DESIGN: Double blind, placebo controlled, randomised group comparison. SETTING: Outpatient clinic for research into osteoporosis. SUBJECTS: 208 healthy women aged 68-72 years who had a bone mineral content of the distal forearm on average 30% below the mean value for healthy premenopausal women. INTERVENTIONS: The 208 women were allocated randomly in blocks of four to two years of treatment with either salcatonin 50 IU, 100 IU, or 200 IU given intranasally or placebo. All groups received a calcium supplement of 500 mg. 32 of the women left the study before its end and 164 women complied with the study criteria throughout. MAIN OUTCOME MEASURES: Bone mineral content of the distal forearm and lumbar spine and rates of vertebral and peripheral fractures after two years of treatment. RESULTS: The average changes in bone mineral content of the spine showed positive outcomes of 1% (95% confidence interval -0.1% to 1.5%) in the group treated with calcium (placebo) and 3% (1.8% to 4.2%) in the group treated with salcatonin 200 IU. There was a significant dose related response to salcatonin, manifested by an increase of 1.0%/100 IU (0.2% to 1.7%, p = 0.008). The rate of patients with new fractures was reduced significantly in the women treated with salcatonin to about one third of that in the non-salcatonin treated women (relative risk 0.23 (0.07 to 0.77)). CONCLUSION: The results suggest that, compared with calcium alone, salcatonin given intranasally reduces the rates of fracture by two thirds in elderly women with moderate osteoporosis. Furthermore, it increases spinal bone mass in a dose dependent manner.

Administration, Intranasal↗
PubMed1992

Nucleotide sequence, organization and characterization of the atp genes and the encoded subunits of Mycoplasma gallisepticum ATPase.

The nucleotide sequence of a 7.8 kbp DNA fragment from the genome of Mycoplasma gallisepticum has been determined. The fragment contains a cluster of nine tightly linked genes coding for the subunits of the M. gallisepticum ATPase. The gene order is I (I-subunit), B (a-subunit), E (c-subunit), F (b-subunit), H (delta-subunit), A (alpha-subunit), G (gamma-subunit), D (beta-subunit) and C (epsilon-subunit). Two open reading frames were identified in the flanking regions; one (ORFU), preceding the I gene, encodes at least 110 amino acids and the other (ORFS), following the C gene, encodes at least 90 amino acids. The deduced amino acid sequences of the various subunits are presented and discussed with regard to the structure, function and differing sensitivity of the M. gallisepticum enzyme to dicyclohexylcarbodiimide and aurovertin. The alpha- and beta-subunits of the F1 portion are well conserved (51% and 65% identity with those of Escherichia coli), whereas the gamma-, delta- and epsilon-subunits, as well as the F0-subunits, show a low percentage identity. Nonetheless, the secondary structure of the F0-subunits show a high degree of similarity to the corresponding subunits of E. coli. Two very strong potential amphipathic alpha-helices are predicted in the delta-subunit and the N-terminus of the b-subunit contains two hydrophobic helical stretches. The possible roles of these structural properties in the close association of the F1 and F0 multisubunit complexes among mycoplasmas are discussed.

Adenosine Triphosphatases↗
PubMed1992

Is heritability a risk factor for postmenopausal osteoporosis?

We investigated heritability as a risk factor for the development of osteoporosis in two randomly selected populations of postmenopausal women and their premenopausal daughters. We determined the familial resemblance in bone mass at three sites; the distal forearm, lumbar spine, and proximal femur, premenopausally and with increasing maternal postmenopausal age. We also examined the bone mass of daughters in relation to mothers with and without osteoporotic fractures. Peak bone mass among premenopausal siblings was significantly correlated at all sites (r = 0.30-0.42, p less than 0.001). The same levels of resemblance were found between early postmenopausal mothers and premenopausal daughters. There was no significant difference in bone mass at any skeletal site between daughters of women with either peripheral or spinal fractures and daughters of women without fractures. We also examined familial resemblance with four biochemical markers of bone turnover (fasting urinary calcium and hydroxyproline, both corrected for creatinine, serum alkaline phosphatase, and plasma bone Gla protein). A generally significant resemblance were seen in premenopausal siblings (r = 0.25-0.39, hydroxyproline NS), but not between premenopausal daughters and postmenopausal mothers. We conclude that peak bone mass is hereditary in the distal forearm, lumbar spine, and proximal femur, but the mother-daughter resemblance explains only about 16% of the variability in daughters' bone mass. Furthermore, daughters of women with a moderate state of osteoporotic fractures are not substantially at an increased risk of having a low peak bone mass compared to the daughters of women without fractures.

Absorptiometry, Photon↗
PubMed1992

Diurnal variation in serum markers of type I collagen synthesis and degradation in healthy premenopausal women.

There are several indications that the functions of human osteoblasts and osteoclasts have circadian rhythms with peak activities occurring at night. It is not known, however, whether the principal function of these cells, namely synthesis and degradation of the organic matrix of bone, of which about 90% is type I collagen, also has a circadian rhythm. This was therefore investigated for both the formation of type I collagen and the degradation of type I collagen in bone using two newly developed serum markers: the serum concentration of the carboxy-terminal propeptide of type I procollagen (PICP) as a marker of formation and the serum concentration of the carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen (ICTP) as a marker of degradation. PICP and ICTP were measured by RIA in samples taken every 3 h over a 24 h period in 12 healthy premenopausal women (age 32 +/- 5 years, mean +/- SD). Both PICP (p = 0.003) and ICTP (p = 0.00003) showed a significant circadian rhythm, with about 20% higher values at night than in the afternoon. We conclude that serum markers of both the formation of new type I collagen and the degradation of old type I collagen in bone exhibit a clear circadian rhythm, with increased activity of both osteoblasts and osteoclasts at night. The etiology of this circadian rhythm is still unknown.

Adult↗
PubMed1992

Measurements of bone mineral density of the proximal femur by two commercially available dual energy X-ray absorptiometric systems.

Two dual energy X-ray absorptiometric (DXA) instruments have recently become commercially available for local bone densitometry: the QDR-1000 (Hologic Inc.) and the DPX (Lunar Radiation Corp.). We report the precision, influence of femoral rotation, correlation and agreement of bone mineral measurements of the proximal femur by these two instruments. In vitro (femur phantom) short-term precision was 1.1%-3.5%, and the long-term precision was 1.2%-3.8%. In vivo (groups of 10 premenopausal and 10 post-menopausal women) short-term precision of duplicate measurements was 1.6%-4.7%, and long-term precision was 1.9%-5.5%. Overall, the precision for Ward's triangle was over 3% and that for the femoral neck and trochanter, 2%-3%. Rotation of a femur phantom produced a statistically significant change in the bone mineral density (BMD) of the femoral neck. Within a clinically relevant range of femoral rotation (20 degrees inward rotation +/- 5 degrees) the coefficient of variation (CV%) increased by a mean factor of 1.1-1.4. Although the correlation (r less than 0.9) between BMD measurements of the proximal femur by the DPX and QDR-1000 in 30 postmenopausal women was high, there was lack of agreement between the two instruments. We found no statistically significant differences between the right and left femur in 30 postmenopausal women. A bilateral femur scan took a mean total time of about 22 min. We conclude that with the introduction of DXA instruments, the precision of bone mineral measurements of the proximal femur has improved. However, for comparability between commercially available DXA instruments, it might be advantageous if units were standardized.

Absorptiometry, Photon↗
PubMed1992

Discriminatory ability of bone mass measurements (SPA and DEXA) for fractures in elderly postmenopausal women.

We investigated the discriminatory ability of forearm bone mineral content (BMCarm) measured by single photon absorptiometry (SPA) and spinal bone mineral density (BMDspine) measured by dual-energy X-ray absorptiometry (DEXA) in 387 elderly postmenopausal women. Of these, 22 had never sustained a fracture (normal), 91 had had less than three vertebral wedge fractures (mild), 51 had experienced a peripheral fracture (moderate), and 24 had had more than three vertebral wedge or compression fractures (severe). BMCarm exceeded BMDspine slightly in the ability to discriminate the mild and moderate groups (P less than 0.01-0.001), whether calculations were performed on raw values or the Z-scores compared with premenopausal women. Receiver operating (ROC) analysis showed that at every cutoff level BMCarm had a similar ability as BMDspine to discriminate between the vertebral fracture (mild and severe) groups and healthy premenopausal and nonfractured postmenopausal women (normal), whereas BMCarm had a significantly higher discriminatory ability of peripheral fractures (P less than 0.05) (moderate) group compared with premenopausal women. We conclude that SPA and DEXA are equally capable as diagnostic procedures in women with established osteoporosis.

Absorptiometry, Photon↗
PubMed1992

Rectal salmon calcitonin for the treatment of postmenopausal osteoporosis.

In a 2-year study, we examined bone mass and calcium metabolism in 36 elderly women with moderate osteoporosis. The study period comprised 1 year of observation, during which the women received no treatment affecting calcium metabolism, and 1 year of treatment, during which all participants received daily salmon calcitonin (sCT) 100 IU rectally and calcium 500 mg. During the observational period a significant bone loss of 1.5% was seen in the forearm (P less than 0.01), whereas the spinal bone mass was virtually unchanged. After institution of treatment, the bone loss was arrested in the forearm and a significant increase of about 2% was seen in the spine (P less than 0.01). The net effect of treatment revealed a positive outcome in both bone compartments (1.9% and 2.9%, P less than 0.05-0.01). Correspondingly, the parameters of bone turnover (serum alkaline phosphatase, plasma bone Gla protein, and fasting urinary hydroxy-proline/creatinine) did not change during the observational period, but significantly declined, 10-30%, during sCT treatment (P less than 0.01-0.001). Tolerance was generally good, although in one woman, anoscopy revealed irritative changes in the rectal mucosa. We conclude that, given rectally, sCT is well absorbed and well tolerated and that it has a beneficial effect on calcium metabolism in moderately osteoporotic women.

Administration, Rectal↗