Biomedical subjects

P Ravn

Publications and source records attributed to P Ravn.

65 records · Page 4Linked to original sources

PubMed1995

Insulin-like growth factors I and II in healthy women with and without established osteoporosis.

We measured serum concentrations of insulin-like growth factors I and II (IGF-I and IGF-II) by radioimmunoassay in 107 healthy women aged 28-78 years and in 116 women with established osteoporosis. The women with established osteoporosis were randomized to a 1-year double-blind, placebo-controlled treatment with continuous estrogen/progestogen, anabolic steroids, salmon calcitonin or placebo and the IGFs were measured every 6 months. Women less than 35 years of age had 29% higher levels of IGF-I (p < 0.001) as compared to women above that age. For women more than 35 years of age, we found no correlation between IGF-I and age (r = 0.02). Correspondingly, we found no significant changes in serum IGF-I in 10 women, who were followed with serial measurements of IGFs every 3 months from 2 years before to 1 year after menopause; IGF-II revealed no correlation with age (r = 0.04). In the group of 116 women with established osteoporosis, IGF-I was 30% lower (p < 0.01) as compared to a group of 19 height-, weight- and age-matched nonfractured women (mean age 64 years). The IGF-II levels were equal in the two groups. Over the 1-year therapeutic intervention period, an increase in IGF-I of 13-15% (p < 0.05) was seen in the nandrolone decanoate-treated group. The same tendency was seen for hormone replacement therapy, although it was not significant. In conclusion, the serum level of IGF-I is high in young women, when peak bone mass is attained, and low in postmenopausal women with established osteoporosis.

Adult↗

PubMed1994

Premenopausal and postmenopausal changes in bone mineral density of the proximal femur measured by dual-energy X-ray absorptiometry.

Total and regional bone mineral density (BMD) of the proximal femur was measured by DXA in 1238 healthy white women. In the 389 premenopausal women, aged 21-54 years, no bone loss was observed before the menopause, except in the femoral neck and Ward's triangle, in which BMD decreased by 0.3%/year (SEE 0.2-0.9%/year, p < 0.001) and 0.6%/year (SEE 0.4-0.8%/year, p < 0.001), respectively. In the postmenopausal women aged 48-75 years, there was a highly significant exponential decay in BMD with age and years since menopause (YSM) in all regions (-0.58 < r < -0.48, p < 0.001). However, YSM was a better predictor of BMD than age. The decrease in BMD in the first 5 years postmenopause reached values of 9-13%. The estimated bone loss after 20 years was 17-30%, greatest in Ward's triangle and smallest in the intertrochanteric region. BMD correlated highly significantly with BMI (0.26 < r < 0.48, p < 0.001). In conclusion, the present study indicates a stable premenopausal bone mass of the proximal femur and a postmenopausal bone loss, which is influenced mainly by YSM within the first 10-15 years after menopause. BMD correlated with body mass index (BMI) in the postmenopausal years, confirming that low BMI constitutes a potential risk factor for osteoporosis.

Absorptiometry, Photon↗

PubMed1994

Total and regional body-composition changes in early postmenopausal women: age-related or menopause-related?

Total and regional body composition were measured in 373 early postmenopausal women aged 49-60 y by dual-energy x-ray absorptiometry to evaluate whether the changes in body composition in the early postmenopausal years are related to menopause itself or merely to age. Both fat mass and fat distribution correlated with age (r = 0.12-0.21, P < 0.05-P < 0.001), but not with years since menopause (YSM). Lean tissue mass, on the other hand, decreased with YSM (r = -0.17, P < 0.001) but was not related significantly to age. Total body bone mineral density decreased with both YSM (r = -0.30, P < 0.001) and age (r = -0.21, P < 0.001). Our study suggests that postmenopausal changes in body fat and fat distribution are more dependent on age than on menopause, but we cannot exclude a separate effect of the menopause. Changes in fat-free mass, including a postmenopausal decline in both soft lean tissue mass and bone mass, are, however, mainly menopause-related

Adipose Tissue↗

PubMed1994

Observations on the formation of deletions on monomeric and dimeric plasmids in Escherichia coli.

We have studied the formation of spontaneous mutations on plasmids present in the monomeric and dimeric states in a recF strain of Escherichia coli. Two test systems were employed: (i) the precise excision of Tn5 from the tetA gene of the plasmid pBR322 and (ii) operator constitutive (Oc) mutations on the pBR322-derived plasmid pPY97. The rate of Oc mutations was increased by a factor of three when this plasmid was present in the dimeric state compared to the monomeric state and the Oc phenotype was caused by small deletions in the operator sequence. No apparent mutational hot-spot was found. The rate of Tn5 excision was increased on dimeric compared to monomeric plasmids. Excision from a dimeric plasmid usually resulted in two types of mutant plasmids; a dimeric plasmid, where the Tn5 had excised from one of the plasmid units, and a monomeric parental pBR322. A mechanisms to account for this is suggested. Complementation tests revealed that the increased mutation rate on dimeric plasmids is the result of dimers being mutaphilic per se, rather than the result of a general, trans-acting increase in mutation rates of the host, induced by the presence of the dimeric plasmid. Furthermore, it was found that the rate of Tn5 excision from plasmids in the monomeric state was increased when the region carrying the inserted Tn5 was duplicated.

Antiporters↗

PubMed1994

Non-major histocompatibility complex-restricted cytotoxic activity of blood mononuclear cells stimulated with secreted mycobacterial proteins and other mycobacterial antigens.

Several observations indicate that non-major histocompatibility complex (MHC)-restricted cytotoxicity, mediated for example by natural killer cells and lymphokine-activated killer cells, may serve as an important antimicrobial defense mechanism. The purpose of the present study was to investigate the influences of different mycobacterial antigens on non-MHC-restricted cytotoxicity and further to investigate the ways by which various lymphocyte subpopulations contribute to the development of this cytotoxicity. Non-MHC-restricted cytotoxicity was induced following stimulation of mononuclear cells with tuberculin purified protein derivative, Mycobacterium bovis bacillus Calmette-Guérin (BCG), short- and long-term culture filtrates of virulent Mycobacterium tuberculosis H37Rv, and 30-31-kDa secreted mycobacterial protein. These antigens also induced proliferation and production of gamma interferon. The CD4+ cells proliferated and expressed interleukin-2 receptors following stimulation with mycobacterial antigens. Depletion studies after antigen stimulation showed that the cytotoxic effector cells were CD16+ CD56+ and CD4-; the CD4+ cells alone did not mediate non-MHC-restricted cytotoxicity. To evaluate the influence of CD4+ cells on the development of non-MHC-restricted cytotoxicity, blood mononuclear cells were depleted of CD4+ cells before antigen stimulation. When mononuclear cells were incubated with purified protein derivative or short-term culture filtrate in the absence of CD4+ cells, cytotoxic activity was reduced. This reduction was abolished by interleukin-2 but not by gamma interferon. We conclude that several mycobacterial antigens are able to induce non-MHC-restricted cytotoxicity. This study indicates that non-MHC-restricted cytotoxicity following stimulation with mycobacterial antigens is induced by cytokines released by antigen-specific activated CD4+ cells.

Antigens, Bacterial↗

PubMed1994

Osteosynthesis of medial humeral epicondyle fractures in children. 8-year follow-up of 33 cases.

33 children with a mean age of 12 (7-15) years had open reduction and osteosynthesis for a displaced fracture of the medial humeral epicondyle. 8 (2-15) years after the operation a clinical and radiographic examination was performed. 22/33 had a prominent scar. No patients had symptoms from the ulnar nerve. Function and range of motion of the elbow were good in all cases, albeit with 20-25 degrees of extension in 3. There were 3 cases of asymptomatic nonunion. Surgery was found to reduce the frequency of nonunion, compared to previous reports of non-operative treatment.

Adolescent↗

PubMed1993

[Salmon calcitonin in osteoporosis. The effect of intranasal application on bone mineral content and fracture frequency in postmenopausal women with manifest osteoporotic changes].

The objective was to study the dose-related response of intranasal salmon calcitonin (Salcatonin) on bone mass and bone turnover and the effect of salcatonin on rates of fracture in elderly women with moderate osteoporosis. A total of 208 healthy women aged 68-72 years, who had a bone mineral content (BMC) of the distal forearm 30% below the mean value for healthy premenopausal women, were examined in a double-blind, placebo-controlled, randomized group comparison study. They were randomized to a two-year daily treatment of either 50 IU, 100 IU, 200 IU Salcatonin or placebo. All received 500 mg calcium daily. In the calcium-(placebo)-treated group the BMC of the spine increased 1%, whereas an increase of 3% was seen in the 200 IU Salcatonin treated group. There was a dose-related response to Salcatonin manifested by an increase in BMC of 1.0%/100 IU. The incidence of new fractures was significantly lower in the women treated with Salcatonin (about one third of that in the non-Salcatonin treated women). In conclusion the results suggest that, compared with calcium alone, Salcatonin given intranasally reduces the rate of fracture by two thirds in elderly women with moderate osteoporosis. Furthermore, it increases spinal bone mass in a dose dependent manner.

Administration, Intranasal↗

PubMed1991

Nosocomial outbreak of cryptosporidiosis in AIDS patients.

OBJECTIVE: To describe a nosocomial outbreak of cryptosporidiosis during four months after June 1989. SETTING: A department of infectious diseases in Copenhagen, seeing about half the patients with AIDS in Denmark. SUBJECTS: 73 HIV antibody negative subjects and 60 antibody positive subjects admitted as inpatients during the transmission period of the outbreak (20 June-14 August), of whom 18 (17 with AIDS, one with AIDS related complex), developed cryptosporidiosis. Two further HIV negative subjects (one departmental secretary, one visiting relative) developed cryptosporidiosis. MAIN OUTCOME MEASURES: Cryptosporidia in stool samples, clinical symptoms, CD4 cell count, HIV antigen concentration, chemotherapeutic treatment. RESULTS: The source of the outbreak was identified as ice from an ice machine in the ward, contaminated by an incontinent, psychotic patient with cryptosporidiosis picking out ice for cold drinks. The mean incubation time was at least 13 days-that is, twice that in HIV-negative patients. Of the 18 patients with AIDS who developed cryptosporidiosis, five recovered, two were symptomless carriers, three died of unrelated causes, and eight died after prolonged diarrhoea. Among the 57 exposed HIV antibody positive inpatients (excluding two patients and the index case with cryptosporidiosis diagnosed elsewhere), significantly more of those who developed symptomatic cryptosporidiosis received oral sulphonamides than those who did not (91%, 10/11 v 48%, 21/44, p less than 0.05). CONCLUSIONS: The clinical and epidemiological findings indicate that infection was the consequence of very small inocula. Increased sensitivity to cryptosporidiosis may be an unrecognised side effect of oral sulphonamide treatment in patients with AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed1988

Malaria chemoprophylaxis in travellers to east Africa: a comparative prospective study of chloroquine plus proguanil with chloroquine plus sulfadoxine-pyrimethamine.

As malaria caused by Plasmodium falciparum has become resistant to chloroquine alternative drug regimens need to be developed. The prophylactic efficacy against malaria and the side effects of chloroquine phosphate 500 mg weekly with proguanil hydrochloride 200 mg daily was compared with the efficacy of chloroquine 500 mg weekly with sulfadoxine 500 mg-pyrimethamine 25 mg weekly in a randomised study of Scandinavian travellers to Kenya and Tanzania during 1984-5. A total of 767 subjects (416 male and 351 female; 384 taking chloroquine phosphate with proguanil hydrochloride and 383 taking chloroquine with sulfadoxine-pyrimethamine) completed a diary on the breakthrough of malaria and the side effects of treatment while taking the drugs. They were also asked to make thick blood films when symptoms like those of malaria occurred, which were sent to and analysed in Denmark. Four subjects taking chloroquine with proguanil hydrochloride and three taking chloroquine with sulfadoxine-pyrimethamine developed falciparum malaria, which was verified microscopically. Side effects were reported by 36 subjects taking chloroquine phosphate with proguanil hydrochloride and 55 taking the other regimen (p = 0.043). The side effects of both regimens were generally mild, but the combination of chloroquine phosphate with proguanil hydrochloride is recommended because it results in fewer side effects. As breakthroughs of malaria occurred at the earliest after seven weeks self treatment should not be recommended for travellers staying only a short time. Thick blood films are useful for diagnosis of suspected cases of malaria, can be prepared by non-specialists in Africa, and can be analysed successfully after long delays.

Adult↗

PubMed1987

Human pharmacokinetics of proguanil and its metabolites.

The pharmacokinetics of proguanil and its metabolites cycloguanil and p-chlorophenylbiguanide were studied in five healthy volunteers taking 200 mg orally for 14 days. A highly sensitive and specific high-performance liquid chromatographic assay was applied, clearly identifying all three compounds in plasma extracts as separate peaks. In four subjects peak plasma concentrations of proguanil (500 to 600 nmol/l) were reached after two to three hours, while cycloguanil and p-chlorophenylbiguanide showed a plateau after three and six hours, respectively. In the fifth subject peak concentrations of proguanil and cycloguanil appeared after seven hours. Trough concentrations (pre-dose in the morning) of proguanil and cycloguanil were about 200 and 100 nmol/l, respectively. Mean half-life of proguanil was estimated to approximately 20 h. The active metabolite cycloguanil constituted 30% of the total plasma drug concentration. The concentration of proguanil was higher in erythrocytes than in plasma, while that of cycloguanil was lower. Relevant clinical studies correlating plasma concentrations to the suppressive activity against malaria will be possible to perform based on the applied method and presented kinetic data.

Adult↗

PubMedDate not supplied

Evidence that increased calcium intake does not prevent early postmenopausal bone loss.

Calcium's ability to prevent bone loss in early postmenopausal women is controversial. We used data on 394 women from the placebo group of the Early Postmenopausal Interventional Cohort study, a clinical trial of alendronate, to investigate the relation of calcium intake to bone loss. Calcium intake was recorded, and bone mineral density (BMD) (in the lumbar spine, total body, forearm, and hip) and biochemical markers of bone turnover (serum total alkaline phosphatase, serum osteocalcin, and urinary N-telopeptide crosslink levels) were measured at baseline and annually thereafter. Women whose baseline calcium intake was <500 mg/d were advised to increase their calcium intake. Mean (+/- SE) BMD decreased by 1.9% +/- 0.16% at the lumbar spine and 1.6% +/- 0.14% at the hip over the 24-month period. Despite wide variations in baseline calcium intake and changes in calcium intake, these measures were not significantly associated with changes in BMD or bone turnover. Even women whose total calcium intake was >1333 mg/d (the highest tertile of total calcium intake) showed a decline in BMD of almost 2%, similar to declines in the lower two tertiles of total calcium intake (<869 and 869-1333 mg/d, respectively). Increased calcium intake resulted in modest mean increases of approximately 200 mg/d. We were unable to demonstrate that increases of this magnitude or much greater (1 g/d) were protective against declines in BMD at any site, even in women who had the lowest calcium intake at baseline. In addition to adequate calcium intake, more effective therapy appears to be required when the therapeutic goal is to increase or maintain BMD.

Bone Density↗