Search PubMed⌕ Search

Biomedical subjects

K Weber

Publications and source records attributed to K Weber.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Quality of life after acetabulum and pelvic ring fractures. Correlation of long-term results with the "Injury Severity Score" (ISS)].

Patients with acetabular (AF) and pelvic ring fractures (BrF) make heavy demands on hospital resources and face difficulties in rehabilitation. From the patients' point of view, milestones in recovery are quality of life and return to productivity. We studied 42 patients with acetabular and 64 patients with pelvic ring fractures over a period of 10 years. The average follow-up took place 4 years after discharge. The injury severity score (ISS) did not correlate to long-term disability and quality of life (QoL) based on the Rosser index, data on return to productivity, or to radiological and clinical outcome. This study emphasizes the need for new injury scoring systems that better predict the recovery and ability to return to work of trauma patients after surviving pelvic fractures. Proper follow-up evaluations should analyze the patients' quality of life and working activity beside traditional items such as radiological and clinical findings.

Acetabulum↗
PubMed2002

Incidence of limb fracture across Europe: results from the European Prospective Osteoporosis Study (EPOS).

The aim of this population-based prospective study was to determine the incidence of limb fracture by site and gender in different regions of Europe. Men and women aged 50-79 years were recruited from population registers in 31 European centers. Subjects were invited to attend for an interviewer-administered questionnaire and lateral spinal radiographs. Subjects were subsequently followed up using an annual postal questionnaire which included questions concerning the occurrence of new fractures. Self-reported fractures were confirmed where possible by radiograph, attending physician or subject interview. There were 6451 men and 6936 women followed for a median of 3.0 years. During this time there were 140 incident limb fractures in men and 391 in women. The age-adjusted incidence of any limb fracture was 7.3/1000 person-years [pyrs] in men and 19 per 1000 pyrs in women, equivalent to a 2.5 times excess in women. Among women, the incidence of hip, humerus and distal forearm fracture, though not 'other' limb fracture, increased with age, while in men only the incidence of hip and humerus fracture increased with age. Among women, there was evidence of significant variation in the occurrence of hip, distal forearm and humerus fractures across Europe, with incidence rates higher in Scandinavia than in other European regions, though for distal forearm fracture the incidence in east Europe was similar to that observed in Scandinavia. Among men, there was no evidence of significant geographic variation in the occurrence of these fractures. This is the first large population-based study to characterize the incidence of limb fracture in men and women over 50 years of age across Europe. There are substantial differences in the descriptive epidemiology of limb fracture by region and gender.

Age Distribution↗
PubMed2002

Is the predictive power of previous fractures for new spine and non-spine fractures associated with biochemical evidence of altered bone remodelling? The EPOS study. European Prospective Osteoporosis Study.

BACKGROUND: In the European Prospective Osteoporosis Study (EPOS), a past spine fracture increased risk of an incident fracture 3.6 - 12-fold even after adjusting for BMD. We examined the possibility that biochemical marker levels were associated with this unexplained BMD-independent element of fracture risk. METHODS: Each of 182 cases in EPOS of spine or non-spine fracture that occurred in 3.8 years of follow-up was matched by age, sex and study centre with two randomly assigned never-fractured controls and one case of past fracture. Analytes measured blind were: osteocalcin, bone-specific alkaline phosphatase, total alkaline phosphatase, serum creatinine, calcium, phosphate and albumin, together with the collagen cross-links degradation products serum CTS and urine CTX. Most subjects also had bone density measured by DXA. RESULTS: Cases who had recent fractures did not differ in marker levels from cases who had their last fracture more than 3 years previously. No statistically significant effect of recent fracture was found for any marker except osteocalcin, which was 17.6% lower in recent peripheral cases compared to unfractured controls (p<0.05) and this was independent of BMD. CONCLUSION: Past fracture as a risk indicator for future fracture is not strongly mediated through increased bone turnover.

Aged↗
PubMed2002

Falls explain between-center differences in the incidence of limb fracture across Europe.

There is important geographic variation in the occurrence of the major osteoporotic fractures across Europe. The aim of this study was to determine whether between-center variation in limb fracture rates across Europe could be explained by variation in the incidence of falls. Men and women, aged 50-79 years, were recruited from population-based registers in 30 European centers. Subjects were followed by postal questionnaire to ascertain the occurrence of incident fractures, and were also asked about the occurrence and number of recent falls. Self-reported fractures were confirmed, where possible, by review of the radiographs, medical record, or subject interview. The age- and gender-adjusted incidence of falls was calculated by center using Poisson regression. Poisson regression was also used to assess the extent to which between-center differences in the incidence of limb fractures could be explained by differences in the age- and gender-adjusted incidence of falls at those centers. In all, 6302 men (mean age 63.9 years) and 6761 women (mean age 63.1 years) completed at least one questionnaire concerning fractures and falls. During a median follow-up time of 3 years, 3647 falls were reported by men and 4783 by women. After adjusting for age and gender, there was evidence of significant between-center differences in the occurrence of falls. There was also between-center variation in the occurrence of upper limb, lower limb, and distal forearm fractures. Variation in the age- and gender-adjusted center-specific fall rates explained 24%, 14%, and 6% of the between-center variation in incidence of distal forearm and upper and lower limb fractures, respectively. Given the constraints inherent in such an analysis, in men and women aged 50-79 years, variation in fall rates could explain a significant proportion of the between-center variation in the incidence of limb fracture across Europe.

Accidental Falls↗
PubMed2002

Effect of sildenafil on oesophageal motor function in healthy subjects and patients with oesophageal motor disorders.

BACKGROUND AND AIMS: Sildenafil blocks phosphodiesterase type 5 which degrades nitric oxide (NO) stimulated 3'5'-cyclic monophosphate (cGMP), thereby relaxing smooth muscle cells in various organs. We used sildenafil as a tool to investigate the role of the NO-cGMP pathway in the oesophagus of healthy volunteers and patients with hypercontractile oesophageal motility disorders. METHODS: Six healthy male volunteers participated in a randomised double blind study on two separate days before and one hour after oral intake of either sildenafil 50 mg or placebo. Oesophageal manometry was performed to determine vector volume of the lower oesophageal sphincter (LOS) and pressure amplitudes of the oesophageal body. Four of the volunteers underwent 12 hour ambulatory oesophageal manometry on two separate days, once with sildenafil 50 mg and once with placebo. An activity index for spontaneous swallowing was calculated for every hour of the study. Eleven patients with hypercontractile oesophageal motility disorders took part in an open study of the effect of 50 mg sildenafil on manometric features of their disorder and on the clinical response to sildenafil taken as required. RESULTS: In healthy subjects, sildenafil significantly reduced LOS pressure vector volume and pressure amplitudes in the distal half of the oesophageal body. In three of four subjects the inhibitory effect of sildenafil lasted at least eight hours. In nine of 11 patients, manometric improvement after sildenafil was observed but only four had an improvement in oesophageal symptoms with sildenafil taken as required. Two of these four patients however experienced side effects and did not want to continue treatment. CONCLUSIONS: Sildenafil lowers LOS pressure and propulsive forces in the body of the oesophagus of healthy subjects as well as in patients with nutcracker oesophagus, hypertensive LOS, and achalasia. The effect of sildenafil on the oesophageal body may last for up to eight hours in healthy volunteers. A subset of patients with hypertensive LOS or nutcracker oesophagus may benefit from sildenafil but side effects are a limiting factor.

Adult↗
PubMed2002

Incidence of vertebral fracture in europe: results from the European Prospective Osteoporosis Study (EPOS).

Vertebral fracture is one of the major adverse clinical consequences of osteoporosis; however, there are few data concerning the incidence of vertebral fracture in population samples of men and women. The aim of this study was to determine the incidence of vertebral fracture in European men and women. A total of 14,011 men and women aged 50 years and over were recruited from population-based registers in 29 European centers and had an interviewer-administered questionnaire and lateral spinal radiographs performed. The response rate for participation in the study was approximately 50%. Repeat spinal radiographs were performed a mean of 3.8 years following the baseline film. All films were evaluated morphometrically. The definition of a morphometric fracture was a vertebra in which there was evidence of a 20% (+4 mm) or more reduction in anterior, middle, or posterior vertebral height between films--plus the additional requirement that a vertebra satisfy criteria for a prevalent deformity (using the McCloskey-Kanis method) in the follow-up film. There were 3174 men, mean age 63.1 years, and 3,614 women, mean age 62.2 years, with paired duplicate spinal radiographs (48% of those originally recruited to the baseline survey). The age standardized incidence of morphometric fracture was 10.7/1,000 person years (pyr) in women and 5.7/1,000 pyr in men. The age-standardized incidence of vertebral fracture as assessed qualitatively by the radiologist was broadly similar-12.1/1,000 pyr and 6.8/1,000 pyr, respectively. The incidence increased markedly with age in both men and women. There was some evidence of geographic variation in fracture occurrence; rates were higher in Sweden than elsewhere in Europe. This is the first large population-based study to ascertain the incidence of vertebral fracture in men and women over 50 years of age across Europe. The data confirm the frequent occurrence of the disorder in men as well as in women and the rise in incidence with age.

Age Distribution↗
PubMed2001

Gene structure and regulation of the murine epithelial calcium channels ECaC1 and 2.

The recently discovered epithelial calcium channels ECaC1 and ECaC2 are thought to play an important role in active calcium absorption in the intestine and kidney. Vitamin D-responsive elements (VDRE) were detected in the promoter sequence of human ECaC1 and regulation of ECaC by the steroid hormone 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) has been postulated. In this study we describe the structure of two murine ECaCs genes, each consisting of 15 exons localized on chromosome 6. Murine ECaC2 expression was found in many target tissues of 1,25-(OH)(2)D(3), including skin and osteoblastic cells, while ECaC1 expression is confined to the kidney. By screening the murine promoter sequences, we detected a putative VDRE in ECaC1 and an estrogen response element in ECaC2. However, experiments in mice with a mutant, nonfunctioning vitamin D receptor showed that expression of ECaC1 in the kidney and of ECaC2 in duodenum is regulated by calcium levels, but not by 1,25-(OH)(2)D(3). Also, estrogen-deficient ovariectomized (OVX) mice and OVX mice supplemented with estradiol showed unchanged duodenal ECaC2 expression compared with control mice. We conclude that ECaC expression in the kidney and the intestine is regulated by extracellular calcium but not by vitamin D or estrogen in vivo in mice.

Amino Acid Sequence↗
PubMed2001

Determinants of HIV-1 shedding in the genital tract of women.

BACKGROUND: Plasma HIV-1 RNA concentration has been the best predictor for risk of heterosexual and perinatal transmission. However, direct contact with HIV-1 present locally in the genital tract might be necessary for transmission. We aimed to assess the relation between HIV-1 shedding (RNA or culturable virus) in female genital secretions and other factors that might affect HIV-1 shedding. METHODS: This was a cross-sectional study within the Women's Interagency HIV Study (WIHS), a prospective longitudinal cohort study of HIV-infected women. We enrolled 311 HIV positive women from Jan 30, 1997 to July 1, 1998. We did clinical assessments, cultured HIV-1, and measured RNA in peripheral blood mononuclear cells (PBMC) and genital secretions. We compared the results with univariate and multivariate analyses. Presence of HIV-1 RNA or culturable virus in genital secretions was defined as HIV-1 shedding. FINDINGS: HIV-1 RNA was present in genital secretions of 57% (152/268) of women whereas infectious virus was detected only in 6% (17/271). Genital tract HIV-1 shedding was found in 80% (130/163) of women with detectable plasma RNA and 78% (116/148) of women with positive PBMC cultures. 33% (27/83) of women with less than 500 copies/mL plasma RNA and 39% (35/90) of those with negative PBMC cultures also had genital tract shedding. INTERPRETATION: Plasma RNA concentration, both qualitatively and quantitatively, was the most important factor in predicting genital HIV-1 shedding, even among women receiving potent antiretroviral therapy. However, HIV-1 shedding did occur in women with less than 500 copies/mL plasma HIV-1 RNA. This finding suggests that a separate reservoir of HIV-1 replication may exist in some women.

Adult↗
PubMed2001

Retention of women enrolled in a prospective study of human immunodeficiency virus infection: impact of race, unstable housing, and use of human immunodeficiency virus therapy.

Even though women and people of color represent an increasing proportion of US acquired immunodeficiency syndrome (AIDS) cases, few research studies include adequate representation of these populations. Here the authors describe recruitment and retention of a diverse group of human immunodeficiency virus (HIV)-infected and at risk HIV-uninfected women in a prospective study operating in six sites across the United States. Methods used to minimize loss to follow-up in this cohort are also described. For the first 10 study visits that occurred during a 5-year period between 1994 and 1999, the retention rate of participants was approximately 82%. In adjusted Cox analysis, factors associated with retention among all women were older age, African-American race, stable housing, HIV-infected serostatus, past experience in studies of HIV/AIDS, and site of enrollment. In an adjusted Cox analysis of HIV-infected women, African-American race, past experience in studies of HIV/AIDS, site of enrollment, and reported use of combination or highly active antiretroviral HIV therapy at the last visit were significantly associated with retention. In adjusted Cox analysis of HIV-uninfected study participants, only the site of enrollment was significantly associated with study retention. These results show that women with and at risk for HIV infection, especially African-American women, can be successfully recruited and retained in prospective studies.

Adult↗
PubMed2001

Mechanism of mammalian mitochondrial DNA replication: import of mitochondrial transcription factor A into isolated mitochondria stimulates 7S DNA synthesis.

The light strand promoter of mammalian mitochondrial DNA gives rise to a primary transcript, but also to the RNA primer necessary for initiation of replication and 7S DNA synthesis as well as 7S RNA. Here we have studied the turnover of 7S DNA in isolated rat liver mitochondria and whether import of mitochondrial transcription factor A (mtTFA), which is necessary for transcription initiation, increases its rate of synthesis. 7S DNA was present as two species, probably due to two different sites of RNA-DNA transition. Time course and pulse-chase experiments showed that the half-life of this DNA is approximately 45 min. Import of mtTFA, produced in vitro, into the mitochondrial matrix in stoichiometric amounts significantly increased the rate of 7S DNA formation. We conclude that isolated rat liver mitochondria faithfully synthesize and degrade 7S DNA and that increased matrix levels of mtTFA are sufficient to increase its rate of synthesis, strongly supporting the hypothesis that this process is transcription primed.

Animals↗
PubMed2001

Transient tyrosine phosphorylation of human ryanodine receptor upon T cell stimulation.

The ryanodine receptor of Jurkat T lymphocytes was phosphorylated on tyrosine residues upon stimulation of the cells via the T cell receptor/CD3 complex. The tyrosine phosphorylation was transient, reaching a maximum at 2 min, and rapidly declined thereafter. In co-immunoprecipitates of the ryanodine receptor, the tyrosine kinases p56(lck) and p59(fyn) were detected. However, only p59(fyn) associated with the ryanodine receptor in a stimulation-dependent fashion. Both tyrosine kinases, recombinantly expressed as glutathione S-transferase (GST) fusion proteins, phosphorylated the immunoprecipitated ryanodine receptor in vitro. In permeabilized Jurkat T cells, GST-p59(fyn), but not GST-p56(lck), GST-Grb2, or GST alone, significantly and concentration-dependently enhanced Ca(2+) release by cyclic ADP-ribose. The tyrosine kinase inhibitor PP2 specifically blocked the effect of GST-p59(fyn). This indicates that intracellular Ca(2+) release via ryanodine receptors may be modulated by tyrosine phosphorylation during T cell activation.

Calcium↗
PubMed2001

Essential roles for four cytoplasmic intermediate filament proteins in Caenorhabditis elegans development.

The structural proteins of the cytoplasmic intermediate filaments (IFs) arise in the nematode Caenorhabditis elegans from eight reported genes and an additional three genes now identified in the complete genome. With the use of double-stranded RNA interference (RNAi) for all 11 C. elegans genes encoding cytoplasmic IF proteins, we observe phenotypes for the five genes A1, A2, A3, B1, and C2. These range from embryonic lethality (B1) and embryonic/larval lethality (A3) to larval lethality (A1 and A2) and a mild dumpy phenotype of adults (C2). Phenotypes A2 and A3 involve displaced body muscles and paralysis. They probably arise by reduction of hypodermal IFs that participate in the transmission of force from the muscle cells to the cuticle. The B1 phenotype has multiple morphogenetic defects, and the A1 phenotype is arrested at the L1 stage. Thus, at least four IF genes are essential for C. elegans development. Their RNAi phenotypes are lethal defects due to silencing of single IF genes. In contrast to C. elegans, no IF genes have been identified in the complete Drosophila genome, posing the question of how Drosophila can compensate for the lack of these proteins, which are essential in mammals and C. elegans. We speculate that the lack of IF proteins in Drosophila can be viewed as cytoskeletal alteration in which, for instance, stable microtubules, often arranged as bundles, substitute for cytoplasmic IFs.

Animals↗
PubMed2001

Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells.

RNA interference (RNAi) is the process of sequence-specific, post-transcriptional gene silencing in animals and plants, initiated by double-stranded RNA (dsRNA) that is homologous in sequence to the silenced gene. The mediators of sequence-specific messenger RNA degradation are 21- and 22-nucleotide small interfering RNAs (siRNAs) generated by ribonuclease III cleavage from longer dsRNAs. Here we show that 21-nucleotide siRNA duplexes specifically suppress expression of endogenous and heterologous genes in different mammalian cell lines, including human embryonic kidney (293) and HeLa cells. Therefore, 21-nucleotide siRNA duplexes provide a new tool for studying gene function in mammalian cells and may eventually be used as gene-specific therapeutics.

Animals↗
PubMed2001

Antifungal actinomycete metabolites discovered in a differential cell-based screening using a recombinant TOPO1 deletion mutant strain.

In the course of a natural product screening for inhibitors of fungal topoisomerase 1 (TOPO 1), extracts from the actinomycete strains WS 1410 and BS 1465 exhibited promising activities. Bioguided fractionation of the culture broth by preparative HPLC methods yielded the collismycins A (1) and B (2) as active principles of strain WS 1410. Out of the mycelial extracts of strain BS 1465 the bioactive new natural products, cyclo-homononactic acid (3) and cyclo-nonactic acid (5) and the structurally related but inactive homononactic acid (4), were isolated. Both collismycin isomers inhibited the recombinant yeast strains ScAL 141 and ScAL 143 (TOPO 1 deletion mutant) in a non-specific manner with an MIC in the range of 2 micrograms/ml. The novel cyclo-homononactic acid (3) and cyclo-nonactic acid (5) showed higher selectivity towards the wild type strain (MIC = 2 micrograms/ml as compared to 10 micrograms/ml for the deletion mutant). All compounds obviously address a target other than TOPO 1 since they do not exhibit activities in a concurrent TOPO 1 enzyme assay.

2,2'-Dipyridyl↗
PubMed2001

[Quality of life after surgical treatment of pelvic ring fractures. Are long-term results predictable?].

Patients with fractures of the pelvic ring and accompanying injuries special of the extremity make heavy demands on hospital resources and face difficulties in rehabilitation. From the patients point of view milestones in recovery are quality of live and return to productivity. We studied 64 patients with pelvic-ring-fractures in a period of 10 years. The follow up was taken 4 years after discharge. PTS-score and AO-classification correlate directly to long-term disability, based on Rosser-Index, and "return to productivity" figures but not always to radiological and clinical outcome. This study emphasizes the need for new injury scoring systems that better predict the recovery and ability to return to work of trauma patients after surviving unstable pelvic fractures. Proper follow-up evaluations should analyse the patient's quality of live and working activity beside traditional item like radiological and clinical findings.

Adolescent↗
PubMed2001

The effects of lifestyle, dietary dairy intake and diabetes on bone density and vertebral deformity prevalence: the EVOS study.

The risk of low and moderate energy fracture is related to bone mineral density (BMD). Yet it is uncertain whether the epidemiologic determinants of fracture risk are the same as for low bone density. The European Vertebral Osteoporosis Study was a population-based prevalence study of vertebral deformity in 36 age-stratified population samples aged 50-80 years. In nearly 4000 subjects (13 centers), BMD measurements were also made at the spine, femoral neck and femoral trochanter. To investigate whether effects of reported physical activity on spine deformity risk were mediated through BMD, we modeled these and other risk factor data with BMD as the dependent variate after adjusting for age, center, sex and body mass index (BMI). The significant determinants of vertebral deformity risk were also entered into logistic models of deformity risk that included BMD measurements as covariates. Both current and lifetime physical activity were positively associated with BMD. This effect was stronger with hip BMD than with spine BMD. Lifetime smoking exposure was associated with reduced BMD. Type 2 diabetes mellitus was associated with increased BMD. Weak positive associations were found between consumption of dairy products and BMD at the three measured sites and these were strengthened by an interaction with measures of physical activity in men. Physical activity in women had the largest beneficial effect in lean women and in women exposed to hormone replacement therapy. When fracture risk was modeled with BMD as a covariate, the lifestyle and dietary determinants became less strongly related to vertebral deformity risk, suggesting that BMD may have acted as an intermediary variable. However, heavy physical activity in men still increased spine deformity risk after adjusting for BMD. It is concluded that physical activity in both genders and milk consumption in young women might protect against vertebral deformities in later life through their effects on bone density. The adverse effect of smoking on BMD was confirmed. Heavy physical activity in men might increase spine deformity risk even when BMD is normal.

Absorptiometry, Photon↗