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Biomedical subjects

E Schwarz

Publications and source records attributed to E Schwarz.

At least 73 records · Page 4Linked to original sources
PubMed1996

Serum antibody reactivity to recombinant mig and whole cell antigens in Mycobacterium avium infection.

Mycobacterium avium is a significant opportunistic pathogen in immunocompromised patients. Moreover, the prevalence of infections in patients without known predisposing conditions has also been increasing in recent years. Patients would greatly benefit from early diagnosis of disseminated infection. Serodiagnostic tests have already been promising in tuberculosis and immunocompetent patients but studies in HIV-infected patients and humoral response to M. avium antigens resulted in conflicting data. We have evaluated the use of the phagocytosis-induced MIG protein of M. avium as a diagnostic antigen. Serum antibody levels of M. avium-infected, HIV-negative patients were significantly elevated for the recombinant MIG (p < 0.001) and also for M. avium whole-cell antigens (p < 0.025) as compared to controls. In contrast, HIV-infected patients with disseminated M. avium infection demonstrated also elevated levels of antibody for the whole-cell antigen (p < 0.00001) but a decreased reactivity for the MIG antigen (p < 0.007). The recombinant antigen proved to have no cross-reactivity with M. tuberculosis antigens as antibody levels were decreased in tuberculosis patients (p < 0.001). Therefore, a simultaneous serological test using recombinant MIG and the whole cell antigens might be helpful in the sometimes problematic diagnosis of M. avium infections in patients without predisposing conditions.

Antibodies, Bacterial↗
PubMed1996

Demand for and utilization of dental services among Hong Kong employees with and without dental benefit coverage.

The objectives of the present study were to investigate the effects of employer-provided dental benefits on the pattern of demand for and utilization of dental services among Hong Kong employees and to analyse whether employees' awareness about an existing dental benefit programme influenced their dental service demand and utilization. Staff from 11 selected companies with and without dental benefits responded to questionnaires concerning their personal factors, demand for dental services, and utilization of dental services and about their awareness of their dental benefit coverage. Overall response rate was 67%. The socio-demographic characteristics of those respondents who were covered and those who were not were similar. Forty per cent of the covered respondents were not aware of their dental benefit coverage, so analysis was performed with three groups of respondents, covered and aware, covered and unaware, and uncovered. A larger proportion of employees in the "aware" group had visited a dentist in the previous 12 months and had visited a dentist for asymptomatic reasons. The "aware" group reported more "low expenditure" items and less "high expenditure" items. Those who were aware of their dental benefit coverage irrespective of the type of scheme reported a significantly higher demand than those who were not aware of their coverage. Demand and utilization of the covered, but unaware, group was more similar to the uncovered group than to the "aware" group. Coverage per se had no apparent effect on the demand for dental services. Further studies will be necessary to establish that higher dental care demand and utilization induced by third party schemes also leads to improved oral health.

Adult↗
PubMed1996

Role of the mitochondrial DnaJ homolog Mdj1p as a chaperone for mitochondrially synthesized and imported proteins.

Mdj1p, a DnaJ homolog in the mitochondria of Saccharomyces cerevisiae, is involved in the folding of proteins in the mitochondrial matrix. In this capacity, Mdj1p cooperates with mitochondrial Hsp70 (mt-Hsp70). Here, we analyzed the role of Mdj1p as a chaperone for newly synthesized proteins encoded by mitochondrial DNA and for nucleus-encoded proteins as they enter the mitochondrial matrix. A series of conditional mutants of mdj1 was constructed. Mutations in the various functional domains led to a partial loss of Mdj1p function. The mutant Mdj1 proteins were defective in protecting the tester protein firefly luciferase against heat-induced aggregation in isolated mitochondria. The mitochondrially encoded var1 protein showed enhanced aggregation after synthesis in mdj1 mutant mitochondria. Mdj1p and mt-Hsp70 were found in a complex with nascent polypeptide chains on mitochondrial ribosomes. Mdj1p was not found to interact with translocation intermediates of imported proteins spanning the two membranes and exposing short segments into the matrix, in accordance with the lack of requirement of Mdj1p in the mt-Hsp70-mediated protein import into mitochondria. On the other hand, precursor proteins in transit which had further entered the matrix were found in a complex with Mdj1p. Our results suggest that Mdj1p together with mt-Hsp70 plays an important role as a chaperone for mitochondrially synthesized polypeptide chains emerging from the ribosome and for translocating proteins at a late import step.

DNA, Fungal↗
PubMed1996

Changes in utilization and cost sharing within the Danish National Health Insurance dental program, 1975-90.

The aims of the analysis were 1) to examine the development in utilization of dental care provided for adults in Denmark under the National Health Insurance during the period 1975-90; 2) to assess the appropriateness of available dental care statistics for studies of oral health trends; and 3) to analyze the price development of dental services during 1975-90 and its impact on patient and Insurance expenses, respectively. Utilization and economic data were retrieved from available registers and analyzed. Three trends were found. First, the utilization has increased more than what could be explained by the population increase; secondly, the panorama of dental services changed from predominantly restorative/extraction services to predominantly diagnostic/preventive services. Thirdly, the price paid by Danish adults for dental care increased disproportionately to other price developments in society. On the basis of traditional health economic theory this development could be expected to affect demand for dental services negatively.

Adult↗
PubMed1996

Changes in demand for dental care among Danish adults, 1975-90.

The aims of this study were 1) to analyze changes in and determining factors for demand for dental care among Danish adults during 1975-90, and 2) to apply standard cohort analysis on sequential cross-sectional survey data, thereby enabling the separation and examination of age, period, and cohort effects. Samples of non-institutionalized Danes aged 15 years and more were interviewed in 1975 (n = 1204), 1980 (n = 1108), 1985 (n = 1123), and 1990 (n = 1003), in accordance with a standardized questionnaire. Overall demand for dental care increased from 59% in 1975 to 76% in 1990; the younger the respondents, the higher the demand. Standard cohort table analysis indicated that the main effect derived from cohort succession; that is, the higher demand of the new cohorts entering the population remained higher than that of previous cohorts. Logistic regression analysis indicated that from 1980 to 1990 the significant predictors for regular dental care shifted from being predominantly predisposing and need variables to predominantly enabling and need variables.

Adolescent↗
PubMed1996

[Multiple chemical sensitivity disorder in patients with neurotoxic illnesses].

The data of 466 subjects suffering from neurologic disorders which are suggested to be caused by neurotoxic agents in their environment retrospectively was evaluated and documented. Among these cases there were 151 subjects with symptoms of Multiple Chemical Sensitivity Disorder (MCSD). The relationship between the neurological health impairments and neurotoxic agents in the environment of these patients was characterised using five different categories (probable = A, possible = B, uncertain = C, unclarified = D, not probable = E). From the 466 patients 320 subjects (69%) could be assigned to the categories A and B, respectively. Within theses 320 cases with chronic neurotoxic health impairments 136 subjects (79 females and 57 males) showed signs of MCSD. Age and gender of cases as well as duration and character of exposure to neurotoxic substances retrospectively were assessed from the explicit files of the patients, which had been made anonymous for this purpose. Frequency of characteristic symptoms of neurotoxicity were analysed. Results are given for patients with neurotoxic health impairments with MCSD (n = 136) and without MCSD (n = 184). Neurotoxic substances which were used as indoor wood preservatives (mainly Pentachlorophenol and/or Lindane) were found to be the causative agents in 63% of the cases with neurotoxic health impairments and MCSD. Other important neurotoxic substances to which the patients were mainly exposed were organic solvents (25%), formaldehyde (15%), dental materials (15%), pyrethroides (13%), and other biocides (19%) (multiple exposures were possible). The time of exposure was calculated as being > or = 10 years for 55% of the patients with MCSD and for 50% of the group with neurotoxic health impairments but without MCSD. Out of the 184 cases with neurotoxic health impairments but without MCSD there were 22%, and out of the 136 cases with MCSD there were 39% who showed all symptoms of chronic fatigue syndrome. 53% of the cases with MCSD had an allergic disposition compared to only 20% of the cases without MCSD. This work is not a controlled epidemiological study but a retrospective documentation and evaluation of data related to environmental medicine. With the present documentation in this purely descriptive manner the proof of a causal relationship was not possible or intended. But because corresponding epidemiological studies are lacking, this documentation can give important information on characteristic features of Multiple Chemical Sensitivity Disorder and chronic neurotoxic health impairments. Such information is essential for planning and carrying out epidemiological studies urgently needed in this field.

Adolescent↗
PubMed1996

[Post-traumatic aneurysma spurium of the subclavian artery].

In peacetime, injuries to the subclavian artery are now very rare. Even more rare are posttraumatic aneurysms and indirect damage to the brachial plexus as a result of injury. The clinical findings, diagnosis and treatment of such a case are described and discussed. Consideration of all the clinical symptoms as a whole is of the outmost importance in the diagnostic process. The development of neurological symptoms in the course of injury with a topographic relationship to the corresponding anatomical structures gave rise to the preliminary diagnosis in this particular case. CT and DSA confirmed the diagnosis. Although surgical treatment is urgently indicated in such cases, resection of the aneurysm as an elective surgical procedure was preferred.

Aneurysm, False↗
PubMed1995

The role of the GrpE homologue, Mge1p, in mediating protein import and protein folding in mitochondria.

Mge1p, a mitochondrial GrpE homologue, has recently been identified in the yeast Saccharomyces cerevisiae and a role for this protein in precursor import has been reported. To dissect the molecular mechanism of Mge1p function, conditional mge1 mutants were constructed. Cells harbouring mutant mge1 accumulated precursor proteins at restrictive temperature. Both kinetics and efficiency of import were reduced in mitochondria isolated from strains possessing mutant mge1. Binding of mitochondrial-Hsp70 (mt-Hsp70) to incoming precursor proteins was abolished at restrictive temperature. Nucleotide-dependent dissociation of mt-Hsp70 from the import component MIM44 was reduced in mitochondria from mutant mge1 strains. Furthermore, at restrictive temperature an increase of incompletely folded, newly imported protein and enhanced protein aggregation was observed in mitochondria isolated from the mutant strains. We conclude that Mge1p exerts an essential function in import and folding of proteins by controlling the nucleotide-dependent binding of mt-Hsp70 to substrate proteins and the association of mt-Hsp70 with MIM44.

Bacterial Proteins↗
PubMed1995

Sorting of cytochrome b2 to the intermembrane space of mitochondria. Kinetic analysis of intermediates demonstrates passage through the matrix.

Precytochrome b2 is targeted to the mitochondrial intermembrane space by a dual targeting sequence comprising 80 amino acids. A kinetic analysis of intramitochondrial sorting was performed. The intermediate-size form accumulated transiently in the matrix. When import was performed in the presence of metal chelators to prevent the first processing by the matrix processing peptidase, > 40% of the imported precursor was localized in the matrix. A deletion of 13 amino acids in the intermembrane space sorting sequence caused partial inhibition of the first processing, and a transient accumulation of the precursor form in the matrix was also observed. The decrease in this matrix-localized precursor form paralleled an increase in the mature-size form in the intermembrane space. A point mutation in the mitochondrial targeting sequence (N-terminal to the sorting sequence) resulted in missorting to the matrix space. Furthermore, a chimeric protein consisting of the initial 85 residues of cytochrome b2 fused to dihydrofolate reductase was partially targeted to the matrix at 15 degrees C, but not at 25 degrees C. Together, the results presented here indicate that cytochrome b2 passes through the matrix on its sorting pathway to the intermembrane space.

Amino Acid Sequence↗
PubMed1995

Dental anxiety in Danish and Chinese adults--a cross-cultural perspective.

The aim of this study was to correlate dental anxiety as reported by two different ethnic groups with socio-demographic factors, dental status, and dental behaviour. Two randomly selected populations aged 35-44 years and 65-74 years were interviewed. The populations comprised 214 and 99 Danes and 384 and 497 Hong Kong Chinese respectively. Dental anxiety was assessed by the Corah Dental Anxiety Score (DAS). Mean DAS scores were significantly higher in Chinese than in Danes (8.7-10.3 and 6.7-8.2, respectively) and higher in the younger than in the older groups. Moderate to phobic dental anxiety was reported by 15% of the Danes and 30% of the Chinese, the latter proportion far beyond what is usually reported in Western populations. Only in the Chinese group did women report more anxiety than men. Regression analysis indicated that only a few of the variables selected to explain anxiety determinants had significant explanatory value. Among Chinese, gender was the most predominant in both age groups followed by perceived condition of teeth in the younger age group. Among Danes, perceived condition of teeth had an explanatory value for both age groups and dental visit pattern was the strongest for the younger age group. In spite of statistical significance, all explanatory values were small and indicate that variables not included in this analysis may exert a greater influence on the variation in dental anxiety. DAS, seemingly, was able to highlight variations in dental anxiety in the populations in spite of their differences and made interpretations feasible with regard to contrasting dental care behaviour and dental status.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Polyvinylidene fluoride monofilament sutures: can they be used safely for long-term anastomoses in the thoracic aorta?

Polyvinylidene fluoride (PVDF) represents an attractive alternative to polypropylene as a monofilament vascular suture because of its satisfactory physicochemical properties, it ease of handling, and its good biocompatibility. However, the polymer's ability to remain mechanically and chemically stable when exposed to a mild hydrolytic environment over the long term has yet to be demonstrated. One in vitro study involved the comparison of the long-term relative resistance of PVDF and polypropylene sutures to hydrolysis for a period of 9 years. The PVDF suture showed major molecular rearrangements from the original ratio of three crystalline structures to the single beta crystalline phase. The observation of some surface oxidation and water inhibition did not significantly modify the tensile strength of the PVDF suture, which retained 92.5% of its original value. In contrast, the polypropylene sample did not undergo any recrystallization but was associated with more oxidation byproducts and more water molecules near the surface, which contributed to a 46.6% loss in initial tensile strength. An in vivo study confirmed that PVDF sutures are biocompatible and are able to maintain satisfactory biostability when used to anastomose thoracic aortic allografts for a period of 6 months in the dog. The cellular reaction of fresh allografts as well as the control autografts to PVDF sutures was minimal. In other allografts that had been preserved in a supplemented medium for 1 week prior to implantation, the PVDF sutures healed satisfactorily with the formation of neocollagen and few macrophages surrounding the monofilament. No evidence of instability at the allograft-host artery junction was observed, confirming that the PVDF sutures were able to ensure a secure anastomosis in the thoracic aorta. PVDF sutures have demonstrated superior long-term biostability in vitro and minimal tissue response in vivo. These are two essential requirements when evaluating the use of a suture for vascular surgery in general and thoracic aortic surgery in particular.

Anastomosis, Surgical↗
PubMed1995

Oral health and dental care in Hong Kong.

With a population of six million people and situated at the South-eastern corner of mainland China, Hong Kong is considered as the gateway between East and West, often playing a role disproportionate to its territorial or population size. The FDI World Dental Congress 1995 provides an impetus to familiarise colleagues worldwide with the oral health and dental care situation in Hong Kong. Water fluoridation was introduced in 1961, which has achieved a continuous low and stable caries prevalence in children as well as in adults. Edentulousness among adults is usually not apparent until after age 55, but at much lower rates than in comparable western industrialised populations. Periodontal conditions in adults are dominated by calculus and shallow pockets. Overall, treatment needs are mainly oral hygiene and simple restorative treatment. Dental awareness is considered low with only a minority of the population seeking dental care on a regular basis. Traditional Chinese health beliefs are common and may influence health behaviour in terms of self- or professional care. Dental care is mainly provided by around 1000 private dental practitioners but special government dental programmes are established for primary school children, who are mainly treated by dental therapists, and for civil servants and their dependents. Dental hygienists are trained in very limited numbers. Dental specialties are under development as part of a newly established Academy of Medicine. Developments are under way to introduce new preventive oriented programmes for pre-school and secondary school age groups.

Adult↗
PubMed1995

Prevalence and structure of dental benefit schemes in Hong Kong.

Before the impact of employer-provided dental benefit schemes on the dental care delivery system can be evaluated in Hong Kong, the prevalence of these schemes and their structures must be established. A mailed questionnaire survey was conducted of a representative group of companies with more than 100 employees (n = 495). Response rate to the mail survey was 38 per cent (n = 186). Non-respondents were stratified according to their nature of business and one third was randomly selected for a follow-up by telephone to which 84 per cent responded (n = 81). After adjustment, 16 per cent of companies of that size were found to be providing dental benefit schemes to their staff. The prevalence was related to the nature of business of the companies. Among companies providing dental benefits, administrators from selected companies were interviewed. It was found that dental benefit schemes could be broadly divided into two types: One characterised by cash-benefit and the other by service-benefit. Treatment items covered by the schemes were mostly simple services such as diagnostic items, simple restorations and simple extractions. The influence of these dental benefit schemes on the dental care-seeking behaviour of the beneficiaries is under investigation.

Health Benefit Plans, Employee↗
PubMed1994

Subcellular relocalization of a long-chain fatty acid CoA ligase by a suppressor mutation alleviates a respiration deficiency in Saccharomyces cerevisiae.

We have isolated an extragenic suppressor, FAM1-1, which is able to restore respiratory growth to a deletion of the CEM1 gene (mitochondrial beta-keto-acyl synthase). The sequence of the suppressor strongly suggests that it encodes a long-chain fatty acid CoA ligase (fatty-acyl-CoA synthetase). We have also cloned and sequenced the wild-type FAM1 gene, which is devoid of suppressor activity. The comparison of the two sequences shows that the suppressor mutation is an A-->T transversion, which creates a new initiation codon and adds 18 amino acids to the N-terminus of the protein. This extension has all the characteristics of a mitochondrial targeting sequence, whilst the N-terminus of the wild-type protein has none of these characteristics. In vitro mitochondrial import experiments show that the N-terminal half of the suppressor protein, but not of the wild-type, is transported into mitochondria. Thus, we hypothesize that the suppressor acts by changing the subcellular localization of the protein and relocating at least some of the enzyme from the cytosol to the mitochondria. These results support the hypothesis that some form of fatty acid synthesis, specific for the mitochondria, is essential for the function of the organelle.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗
PubMed1994

Mitochondrial protein import: mechanisms, components and energetics.

The transport of nuclear-encoded proteins from the cytosol into mitochondria is mediated by targeting (signal) sequences present on precursor forms. Most precursors of the mitochondrial matrix possess amino-terminal signals which characteristically contain hydroxylated and basic amino acids and lack acidic residues. With a minority of precursor proteins, internal sequence motifs can direct proteins to the mitochondria (Pfanner, N., Hoeben, P., Tropschug, M. and Neupert, W. (1987) J. Biol. Chem. 262, 14851-14854). The presence of a mitochondrial targeting sequence alone, however, is not sufficient for specific targeting to the organelle and further to the various subcompartments. There is the need for components which recognise the targeting sequences and others which keep the precursor protein in a translocation-competent form. Beyond the recognition step, components are required which mediate translocation across the mitochondrial membranes. Mitochondria posses two translocation machineries, one in the outer membrane and one in the inner membrane. The matrix space harbors a number of factors which participate in the import of proteins, in their unfolding and folding. Energy is required at several steps of these processes.

Cytosol↗
PubMed1994

XDJ1, a gene encoding a novel non-essential DnaJ homologue from Saccharomyces cerevisiae.

The gene encoding a novel DnaJ-like protein, termed Xdj1, has been identified by amplification of Saccharomyces cerevisiae genomic DNA. An open reading frame of 1380 bp was detected. Disruption of XDJ1 did not yield any detectable new phenotype. A double-deletion strain containing a disruption of both XDJ1 and YDJ1, another gene coding for a DnaJ-like protein, was still viable. Under a variety of growth conditions, no XDJ1 transcripts could be detected by Northern blot analysis and no translation product was found by immunoblotting with antibody against Xdj1 produced in Escherichia coli. Thus, XDJ1 is either expressed only under very specific conditions or represents a silent gene.

Amino Acid Sequence↗
PubMed1994

Mdj1p, a novel chaperone of the DnaJ family, is involved in mitochondrial biogenesis and protein folding.

Mdj1p, a novel member of the DnaJ family, is a heat shock protein that is associated with the inner membrane of mitochondria of Saccharomyces cerevisiae. Disruption of the MDJ1 gene resulted in a petite phenotype, loss of mitochondrial DNA, and inviability at 37 degrees C. Import of precursor proteins was not affected by a lack of Mdj1p, but folding of newly imported proteins was markedly impaired. The efficiency of refolding of a tester protein, dihydrofolate reductase, was significantly reduced in mitochondria lacking Mdj1p after incubation at elevated temperature. We conclude that Mdj1p is an important mitochondrial chaperone that participates in the folding of newly imported proteins and in the protection of proteins against heat denaturation and aggregation.

Amino Acid Sequence↗