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Biomedical subjects

M Weber

Publications and source records attributed to M Weber.

At least 199 records · Page 11Linked to original sources
PubMed2000

Occurrence of lectins and hydrophobicity of bacteria obtained from biofilm of hospital catheters and water pipes.

Bacteria isolated from biofilms of water distribution pipes and colonized catheters from hospitalized patients were studied for their haemagglutination ability, expression of lectins and hydrophobicity. Higher haemagglutination ability of clinical strains for human red blood cells was demonstrated, which could be an expression of their adaptation to the human ecosystem. Environmental strains had higher hydrophobicity, possibly related to adaptation to a low nutritive ecosystem. Expression of lectins was relatively low and comparable in both bacterial populations, but carbohydrate specificities were very different, possibly related to a different implication of these structures in the two ecosystems.

Biofilms↗
PubMed2000

Sulfate assimilation in higher plants characterization of a stable intermediate in the adenosine 5'-phosphosulfate reductase reaction.

The enzyme catalysing the reduction of adenosine 5'-phosphosulfate (AdoPS) to sulfite in higher plants, AdoPS reductase, is considered to be the key enzyme of assimilatory sulfate reduction. In order to address its reaction mechanism, the APR2 isoform of this enzyme from Arabidopsis thaliana was overexpressed in Escherichia coli and purified to homogeneity. Incubation of the enzyme with [35S]AdoPS at 4 degrees C resulted in radioactive labelling of the protein. Analysis of APR2 tryptic peptides revealed 35SO2-3 bound to Cys248, the only Cys conserved between AdoPS and prokaryotic phosphoadenosine 5'-phosphosulfate reductases. Consistent with this result, radioactivity could be released from the protein by incubation with thiols, inorganic sulfide and sulfite. The intermediate remained stable, however, after incubation with sulfate, oxidized glutathione or AdoPS. Because truncated APR2, missing the thioredoxin-like C-terminal part, could be labelled even at 37 degrees C, and because this intermediate was more stable than the complete protein, we conclude that the thioredoxin-like domain was required to release the bound SO2-3 from the intermediate. Taken together, these results demonstrate for the first time the binding of 35SO2-3 from [35S]AdoPS to AdoPS reductase and its subsequent release, and thus contribute to our understanding of the molecular mechanism of AdoPS reduction in plants.

Adenosine Phosphosulfate↗
PubMed2000

Evaluation of a new PCR assay with competitive internal control sequence for blood donor screening.

BACKGROUND: High-throughput nucleic acid testing for transfusion-relevant viruses by PCR requires contamination-proof methods with high sensitivity and validity. A new PCR reagent kit (TaqMan, PE BioSystems) reduces the risk of carry-over contamination by eliminating post-PCR processing. STUDY DESIGN AND METHODS: Oligonucleotide design was done with software specialized for designing the assays' (TaqMan) primers and probes. A template-derived competitive internal control sequence designed through site-directed mutagenesis was used to reveal failures in amplification. Assay sensitivity was determined for single-donor and single-patient testing and by spiking sample mini-pools. Three seroconversion panels were tested. RESULTS: Sensitivity is high, reaching 300 HBV genomes per mL of single-patient material on direct testing. A detection limit of 1000 HBV genome equivalents per mL of donor plasma is achieved for 96 pooled samples. The window period for HBV infection was reduced by 17, 10, and 63 days from that for HBsAg screening in three seroconverting donors. CONCLUSION: The assay provides sufficient sensitivity to be superior to HBsAg screening in transfusion medicine and will be useful in clinical laboratories because of its ease of handling.

Blood Donors↗
PubMed2000

Is there a need for routine testing of ICD defibrillation capacity? Results from more than 1000 studies.

AIMS: Benefits and complications of postoperative implantable cardioverter-defibrillator tests are controversial matters. This study sought to assess the necessity of defibrillation function tests after implantation. METHODS AND RESULTS: We retrospectively analysed 1007 implantable cardioverter-defibrillator tests in 587 systems and 556 patients. Nine hundred and thirty implantable cardioverter-defibrillator tests (89.4%) were routinely performed. Seventy-one tests (7%) were performed after a change in the antiarrhythmic drug regimen and six tests (0.60%) because of a suspected dysfunction of the implantable cardioverter-defibrillator. During routine tests, four systems (0.4%) failed to defibrillate the patient. However, in all but one test, abnormalities of the system had been observed before the test. After the addition of antiarrhythmic drugs, two of 71 implantable cardioverter-defibrillator systems (2.8%) failed to defibrillate the patient. One of six systems tested due to a suspected dysfunction failed to defibrillate the patient. During 16 tests (1.6%), complications occurred. CONCLUSIONS: Our experience demonstrates that postoperative tests of the defibrillation function of implantable cardioverter-defibrillators rarely reveal dysfunctions. As testing is unpleasant for the patient and not free of complications, tests might be restricted to those patients in whom a dysfunction is suspected and to those patients in whom class I or class III antiarrhythmic drugs have been added to the antiarrhythmic drug regimen.

Adolescent↗
PubMed2000

Evaluation of the bactericidal efficiency of a 2% alkaline glutaraldehyde solution on Mycobacterium xenopi.

Mycobacterium xenopi (M. xenopi) has been implicated in hospital-acquired infections associated with colonization of hospital water systems. M. xenopi is considered to be as resistant as other atypical mycobacteria, which are known to be resistant to many disinfecting treatments. However, the efficacy of disinfectants on this organism has not yet been studied. Therefore we decided to evaluate its susceptibility to 2% alkaline glutaraldehyde solution, which is commonly used in hospitals. Tests were conducted using five strains of M. xenopi: three isolated from human samples, an environmental strain and a collection strain. We used a membrane filtration assay and counted surviving bacteria before and after several exposure times (5, 15, 30 and 60 min) with the disinfecting solution. The log10 reduction factor of organisms achieved within 60 min contact ranged from 2.5 to 7.5. This showed M. xenopi to be more resistant to disinfectants than M. tuberculosis or M. smegmatis and suggested that environmental strains may be more resistant to alkaline glutaraldehyde than those isolated from human samples.

Cross Infection↗
PubMed2000

Peristimulus time histograms (PSTHs)--a marker for upper motor neuron involvement in ALS?

Upper motor neuron involvement in ALS has been widely studied by means of transcranial magnetic stimulation and various imaging methods, such as magnetic resonance imaging, proton emission tomography, single photon emission computer tomography and magnetic resonance spectroscopy. Although almost all of these methods have detected 'abnormalities' of the motor cortex, no method has yet proven to be capable of monitoring disease progression. We and others have used peristimulus time histograms (PSTH) to evaluate corticomotoneuronal dysfunction. The primary peak (PP) in the PSTH reflects the initial rising phase of the excitatory post-synaptic potential evoked at the anterior horn cell by converging corticomotoneurons. In ALS, the PP is delayed in onset, increased in duration, and desynchronized. These abnormalities become more pronounced over time. Delayed PPs also occur more frequently in non-hereditary ALS (nHALS) with disease progression and are a hallmark of the autosomal recessively inherited D90A Cu-Zn SOD mutation. Evidence indicates that in this particular mutation, as well as in nHALS, the fast-conducting monosynaptic pathway originating from large pyramidal Betz cells is preferentially lost, whereas a slow-conducting pathway seems to be spared. This is most likely due to the enormous metabolic demand of the large pyramidal cells, which may explain the selective vulnerability of the most recent phylogenetic system to develop in the human nervous system.

Amyotrophic Lateral Sclerosis↗
PubMed2000

Neurophysiological evaluation of cortical function in the early diagnosis of ALS.

The corticomotoneuronal system is selectively vulnerable in amyotrophic lateral sclerosis (ALS). In the past it has been difficult to evaluate the upper motor neuron component of this system. Recent studies using functional imaging and neurophysiological methods are now available as potential surrogate markers in the early diagnosis of ALS. We have used peristimulus time histograms (PSTHs) to evaluate the integrity of the motor cortex in ALS and in particular the cortical colonies that synapse with single anterior horn cells. The motor cortex in ALS becomes hyperexcitable early in the course of the disease and this may persist for some time. This is reflected in the PSTH by a desynchronized, complex response. Evidence indicates that this prime abnormality in ALS is supraspinal in origin and probably due to increased repetitive firing of the corticomotoneuron. The hyperexcitability is likely to be due to a combination of increased excitation at the level of the motor cortex and decreased inhibition due to dysfunction of the cortical inhibitory interneurones that modulate the output of the corticomotoneurone.

Anterior Horn Cells↗
PubMed2000

Preserved slow conducting corticomotoneuronal projections in amyotrophic lateral sclerosis with autosomal recessive D90A CuZn-superoxide dismutase mutation.

Recently, a subgroup of the amyotrophic lateral sclerosis (ALS) syndrome associated with mutations in the gene encoding the free radical scavenging enzyme CuZn-superoxide dismutase (CuZn-SOD, SOD1) has been identified. Some 67 different mutations have been reported worldwide to date, comprising about one-fifth of familial ALS cases in the populations studied. The autosomal recessively inherited D90A CuZn-SOD mutation has been associated with a very slowly progressive, clinically distinct phenotype, and is neurophysiologically characterized by very slow central motor conduction. It is not known which physiological and/or biochemical mechanisms are responsible for the different clinical course. To delineate ALS associated with this particular CuZn-SOD mutation from ALS without mutations, we performed a detailed neurophysiological study of the corticomotoneuronal function using peristimulus time histograms (PSTHs) in eight ALS patients homozygous for the D90A CuZn-SOD mutation. The results were compared with those obtained in 12 non-hereditary ALS patients and 11 healthy subjects. PSTHs were constructed from three to seven different, voluntarily recruited motor units of the extensor digitorum communis muscle (EDC) in each patient. The onset latency, number of excess bins, duration and synchrony of the primary peak were analysed. All measurements differed significantly between healthy controls and the D90A patients (P < 0.0007). The mean onset latency of the primary peak in D90A patients was 35.3 ms, compared with 24.2 ms for non-hereditary ALS patients and 19.3 ms for normal subjects (P < 0.0000). Delayed primary peaks in the D90A patients were desynchronized and characteristically preceded by a marked suppression phase. This suppression phase was not seen in non-hereditary ALS patients. We conclude that the mainly slow conducting and/or polysynaptic corticomotoneuronal connections are preserved in the D90A homozygous cases, and that the cortical and possibly spinal inhibitory circuitry is preserved. These events may partially protect the motor neurons, slowing down the degenerative process.

Adult↗
PubMed2000

3-(tert-Butyloxycarbonylamino)bicyclo

In the room-temperature X-ray structure of the N-Boc-protected derivative of the novel 3-aminobicyclo[1.1.1]pentanecarboxylic acid, C(11)H(17)NO(4), the interbridgehead distance in the bicyclo[1.1. 1]pentane cage is 1.852 (2) A. The carboxyl and parts of the blocked amino group are almost in plane with one of the cage triangles. N-H. O and O-H.O hydrogen bonds generate infinite corrugated molecular chains in the crystal lattice.

Journal Article↗
PubMed2000

Predictors of syphilis seroreactivity and prevalence of HIV among street recruited injection drug users in Los Angeles County, 1994-6.

OBJECTIVES: To describe HIV prevalence and the association between syphilis incidence and sexual and drug injection risk behaviours in a cohort of street recruited injecting drug users (IDUs) in Los Angeles County, between 1994 and 1996. METHODS: During the study period, 513 street recruited African-American and Latino IDUs were screened for syphilis and antibodies to HIV. Subjects were administered a risk behaviour survey at baseline and followed up at 6 month intervals for 18 months with repeated interviews and serological screening. Rate ratios were used to examine associations between syphilis incidence and demographic characteristics and risk behaviours. A proportional hazard model was used to identify predictors of syphilis incidence independent of demographic characteristics. RESULTS: 74% of the sample were male, 70% African-American, 30% Latino; and the median age was 43 years. Overall baseline serological prevalence of HIV was 2.5% and of syphilis 5.7%. None of the participants were co-infected for HIV and syphilis at baseline or at any of the 6 month follow ups. Among 390 eligible IDUs retained for analysis of incidence data, the overall syphilis incidence was 26.0 per 1000 person years. Higher syphilis incidence was found for women compared with men (RR = 2.70; 95% CI 1.60, 4.55), and for those 44 years of age or younger compared with those 45 years of age and older (RR = 2.26; 95% CI 1.25, 4.08). African-Americans were more likely to be syphilis incident cases when compared with Latinos, although the difference did not reach statistical significance (RR = 1.27; 95% CI 0.72, 2.23). In bivariate analysis, risk behaviours significantly associated with higher syphilis incidence included injection of cocaine, "speedball" and heroin, "crack" smoking, recency of first injection event, backloading of syringes, injecting with others, exchanging drugs or money for sex, multiple sex partners, and non-heterosexual sexual preference. Variables that significantly predicted syphilis infection at follow up in the multivariate analysis included multiple sex partners (RR = 7.8; 95% CI 2.4, 25.0), exchanging money for sex (RR = 3.0; 95% CI 0.9, 9.6), and recent initiation to injection drug use (RR = 4.6; 95% CI 1.1, 18.8). CONCLUSION: Syphilis transmission among IDUs in Los Angeles County remains a serious public health concern, particularly among IDUs who engage in trading of sex for money or drugs. Although low, the prevalence of HIV observed in this study constitutes a serious concern because of the potential for expanded HIV transmission in this susceptible population of IDUs with high syphilis incidence. Enhanced case finding screening efforts and prevention of transmission of sexually transmitted infections should specifically target hard to reach IDUs and their sexual partners.

Adolescent↗
PubMed2000

The family history of patients with primary or secondary antiphospholipid syndrome (APS).

OBJECTIVE: To evaluate familial history for evidence of antiphospholipid syndrome (APS) and autoimmune disease in rheumatology department patients with primary or secondary APS. METHODS: We retrospectively studied patients with APS and systemic lupus erythematosus (SLE) managed at the Rheumatology Department of the Bichat University Hospital, Paris, between 1987 and 1996. Data were collected by chart review and by a 1997 standardized telephone interview. RESULTS: We identified 108 patients with APS managed during the ten-year study period. According to classical classification criteria, 39 patients had primary antiphospholipid syndrome (PAPS) and 69 secondary antiphospholipid syndrome (SAPS). Family history data were obtained for 29 (74%) and 55 (80%) PAPS and SAPS patients. respectively (78% of the 108 patients). Twelve PAPS (41% and 19 SAPS (35%) patients had one or more relatives with evidence of at least one clinical feature of APS such as thrombosis or recurrent fetal loss; of these patients, seven in the PAPS (24%) and 11 in the SAPS (20%) group had two or more relatives with evidence of a clinical feature of APS. Three PAPS (10%) and 14 SAPS (25%) patients had one or more family members with an autoimmune disease. CONCLUSION: A positive family history for autoimmune disease and/or antiphospholipid syndrome is common in patients with PAPS or SAPS. This finding supports a genetic contribution to APS. The percentage of a positive family history for autoimmune disease tend to be higher in patients with SAPS than in those with PAPS.

Abortion, Habitual↗
PubMed2000

Identification and treatment of Moniliformis clarki (Acanthocephala) in cotton-topped tamarins (Saguinus oedipus).

Ten cotton-topped tamarins (Saguinus oedipus) were infected with Moniliformis clarki a parasitic acanthocephalan. One animal died of intestinal perforation and peritonitis before treatment was initiated. Five of the remaining tamarins were treated successfully with oral albendazole at either 50 mg/kg b.i.d. for 16 days or 100 mg/kg b.i.d. for 3 days, then repeated biweekly for four treatments. A less-intensive treatment regime of 50 mg/kg albendazole orally s.i.d. for 3 days and monthly repeated treatments was unsuccessful. Parasites were removed via surgical enterotomy from two animals, both of which continued to shed acanthocephalan eggs postoperatively.

Albendazole↗
PubMed2000

IgG anti-beta2-glycoprotein I antibodies in adult patients with systemic lupus erythematosus: prevalence and diagnostic value for the antiphospholipid syndrome.

OBJECTIVE: To investigate the prevalence of serum anti-beta2-glycoprotein I (anti-beta2-GPI) antibodies and other antiphospholipid antibodies (aPL) in patients with systemic lupus erythematosus (SLE). To study their diagnostic value for the antiphospholipid syndrome (APS). METHODS: Anti-beta2-GPI and IgG anticardiolipin (aCL) were determined in sera from 102 consecutive patients with SLE using ELISA. Serum and plasma tests were also done for lupus anticoagulant (LAC), syphilis, and antibodies to dsDNA. Clinical and laboratory features of APS were observed. RESULTS: Prevalences were 23.5% for aCL and 18.6% for anti-beta2-GPI. Correlations between the presence of aCL and anti-beta2-GPI and between their titers were statistically significant (p<0.0001). No associations were found between anti-beta2-GPI and disease activity criteria (SLEDAI, ECLAM, dsDNA). Anti-beta2-GPI were significantly associated with LAC (p = 0.005), APS (p = 0.005), and a high aCL titer (aCL > 5 SD; p< or =0.001). LAC was the best diagnostic criterion for APS. CONCLUSION: These data suggest that determination of anti-beta2-GPI in addition to aCL and LAC is unlikely to improve the diagnosis of APS in patients with SLE.

Adolescent↗
PubMed2000

["Reperfusion collapse" phenomenon during post-ischemic reperfusion in experiment].

Postischemic changes of central and regional hemodynamic while various reperfusion regimens have been studied on animal experimental model. We had revealed that despite vasodilatation, peripheral vascular resistance in the postischemic extremity rises, as a result of reperfusion by the lowered perfusion volume. Such phenomenon has been named as "reperfusion-collapse". In spite of the microcirculation disorders progression there have been no significant rising of the peripheral vascular resistance as well as worsening of the regional hemodynamic indexes in the postischemic limb during reperfusion by either normal or increased perfusion volume.

Acute Disease↗
PubMed2000

[Isolated dissection of the basilar artery].

Two cases of isolated dissection of the basilar artery responsible for ischemic stroke are reported. This rare condition is still associated with a poor outcome. Most patients were male and the clinical presentation consisted of ischemic symptoms or subarachnoid hemorrhage in posterior circulation. Angiography and Magnetic Resonance Imaging are usefull for the diagnostic, showing parietal hematoma, or as for our first case, double lumens. Optimal therapeutic is unknown.

Adult↗