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Biomedical subjects

M Weber

Publications and source records attributed to M Weber.

At least 145 records · Page 8Linked to original sources
PubMed2001

Multiple founder effects in spinal and bulbar muscular atrophy (SBMA, Kennedy disease) around the world.

SBMA (spinal and bulbar muscular atrophy), also called Kennedy disease, is an X-chromosomal recessive adult-onset neurodegenerative disorder caused by death of the spinal and bulbar motor neurones and dorsal root ganglia. Patients may also show signs of partial androgen insensitivity. SBMA is caused by a CAG repeat expansion in the first exon of the androgen receptor (AR) gene on the X-chromosome. Our previous study suggested that all the Nordic patients with SBMA originated from an ancient Nordic founder mutation, but the new intragenic SNP marker ARd12 revealed that the Danish patients derive their disease chromosome from another ancestor. In search of relationships between patients from different countries, we haplotyped altogether 123 SBMA families from different parts of the world for two intragenic markers and 16 microsatellites spanning 25 cM around the AR gene. The fact that different SBMA founder haplotypes were found in patients from around the world implies that the CAG repeat expansion mutation has not been a unique event. No expansion-prone haplotype could be detected. Trinucleotide diseases often show correlation between the repeat length and the severity and earlier onset of the disease. The longer the repeat, the more severe the symptoms are and the onset of the disease is earlier. A negative correlation between the CAG repeat length and the age of onset was found in the 95 SBMA patients with defined ages at onset.

Exons↗
PubMed2001

Gastrointestinal transit of solid radiopaque markers in large and giant breed growing dogs.

Observations on food tolerance in dogs have shown that some breeds, especially the giant breeds, have a greater digestive sensitivity. One of the consequences common in these breeds is a higher faecal water content and a poor faecal quality. This could be explained, at least in part, by limited digestive capacity and function in giant breed dogs. In this report, the gastric emptying that represents one parameter of the digestive function was studied in large and giant breed dogs during their growth. Six Great Danes (GD) and six Giant Schnauzers (GS) were fed small radiopaque markers mixed with a test diet at 12, 22 and 36 weeks of age. Abdominal radiographs were made every 30 min for a period of 4 h and then hourly until 12 h. At 12 weeks of age, the gastric emptying pattern was similar in both breeds. However, from 22 weeks of age, the gastric emptying of the GD was significantly more rapid than that of GS. The gastric emptying of small markers tended to slow down in growing dogs, especially in GS. A significant positive correlation between the gastric emptying time of 50% of markers and the body weight was found. These results show that GD have a lower gastric retention time of foods, which could lead to a poor digestion and an altered absorption of nutrients. These could explained why digestive function and sensitivity could be different in dogs from different sizes and breeds.

Age Factors↗
PubMed2001

Fatal gastrointestinal infection with 'Flexispira rappini'-like organisms in a cat.

A 4-month-old male British Blue cat with catarrhal to haemorrhagic enteritis showed massive colonization of the stomach, small intestine and caecum with spiral-shaped bacilli. In the stomach, organisms were located in foveolae and gland lumina and within unaltered and degenerate epithelial cells. Inflammatory infiltration was moderate and T cell dominated. In the intestine, bacilli were found in the gut lumen, berween villi, in crypt lumina and within epithelial cells. Degeneration of crypt epithelial cells as well as crypt dilation and moderate to massive macrophage-dominated infiltration of the mucosa and submucosa were observed. Immunohistochemically, bacilli were positive with an antibody against Helicobacter. Ultrastructurally, the organisms strongly resembled 'Flexispira rappini', a spiral-shaped Helicobacter species known as a normal intestinal colonizer in dogs and mice.

Animals↗
PubMed2001

Antitachycardia pacing for rapid VT during ICD charging: a method to prevent ICD shocks.

In patients with ICDs, rapid VTs are usually treated with shocks. It is unknown, if antitachycardia pacing (ATP) delivered once for rapid VT during capacitor charging can avoid painful shocks without increasing the risk of syncope. In patients in whom rapid monomorphic VT (cycle length 300-220 ms) could be reproducibly induced during predischarge ICD testing, the success of cardioversion (defibrillation threshold plus 10 J) and a single ATP attempt (burst with 8 or 16 stimuli) was compared using a randomized crossover study design. Consciousness of the patients was checked by the signal from a button constantly pushed by the patient. In 20 patients (ejection fraction 0.50 +/- 0.19) rapid VTs (253 +/- 26 ms) were reproducibly induced. A single burst successfully terminated 11 (55%) of 20 rapid VTs, 6 episodes could not be terminated with a single burst pacing and 3 VTs accelerated. Rapid VTs not terminated by ATP were significantly faster than those that could be terminated (246 vs 258 ms, P = 0.026). Cardioversion (19 +/- 3 J) terminated the VTs in all cases. No patient suffered syncope during rapid VTs. A single ATP may terminate rapid VT with cycle lengths < 300 ms in 55% of patients without increasing the risk of syncope. Therefore, in rapid VTs one attempt of ATP may be suitable as an additional therapy option during ICD capacitor charging to avoid painful shocks without compromise of safety. Thus, future ICDs should implement the option of ATP during charging of capacitors.

Adult↗
PubMed2001

6-Hydroxykynurenic acid and kynurenic acid differently antagonise AMPA and NMDA receptors in hippocampal neurones.

6-Hydroxykynurenic acid (6-HKA), a derivative of kynurenic acid (KYNA) extracted from Ginkgo biloba leaves, was tested for its putative glutamate receptor (GluR) antagonism in comparison to the scaffold substance. The patch-clamp method together with fast-application techniques were used to estimate inhibition by 6-HKA and KYNA of agonist binding at NMDA and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (NMDARs and AMPARs) of CA1 pyramidal neurones. 6-Hydroxykynurenic acid proved to be a low-affinity antagonist. When comparing with KYNA, 6-HKA was less potent at NMDARs (IC(50) = 136 versus 59 microM), but showed a higher affinity to AMPARs (K(B) = 22 versus 172 microM). The replacement of 6-HKA and KYNA by glutamate was investigated on outside-out patches. Both antagonists competitively inhibited AMPAR responses and displayed fast unbinding kinetics, but the derivative was significantly slower displaced than KYNA (tau = 1.63 versus 1.22 ms). Our findings demonstrate that 6-hydroxylation considerably changes the pharmacological profile of KYNA. Among the 6-derivatives of KYNA, 6-HKA shows the highest affinity to AMPARS: Despite its relatively low lipophily, these properties might be of clinical relevance under conditions that compromise the integrity of the blood-brain barrier. Furthermore, 6-HKA should be a useful tool to analyse glutamate-mediated synaptic responses.

Animals↗
PubMed2001

Comparison of sludge and clinical isolates of Listeria monocytogenes.

AIMS: Listeria monocytogenes strains isolated in the same geographical area from sewage sludge and from patients presenting with listeriosis were compared. METHODS AND RESULTS: All isolates were typed by serotyping, phage typing and SmaI/ApaI pulsed-field gel electrophoresis (PFGE). Among the sludge isolates (n=32), 22 subtypes could be distinguished by the combination of all typing methods. The human isolates (n=11) were distributed into 10 subtypes which clearly differed from those observed among sludge isolates, except for one cluster formed by two related human isolates which showed high similarity in PFGE patterns (SmaI: 92%; ApaI: 89.5%) with one sludge isolate. CONCLUSION: These results suggest the existence of an epidemiological link between sludge and human isolates, but they may also be reflecting the distribution of L. monocytogenes types within the environment. SIGNIFICANCE AND IMPACT OF THE STUDY: Sludge and human L. monocytogenes may be related but further epidemiological studies are necessary to elucidate this point.

Bacterial Typing Techniques↗
PubMed2001

INI1 mutations in meningiomas at a potential hotspot in exon 9.

Rhabdoid tumours have been shown to carry somatic mutations in the INI1 (SMARCB1/hSNF5) gene. A considerable fraction of these tumours exhibit allelic losses on chromosome 22. Allelic loss on 22q also is characteristic for meningiomas, however most of these alterations are considered to be associated with mutations of the NF2 gene. We examined a series of 126 meningiomas for alterations in the INI1 gene. Four identical somatic mutations in exon 9 were detected resulting in an exchange of Arg to His in position 377 of INI1. Our observations were reproduced both by using DNA from a new round of extraction and by employing overlapping primers. This mutational hotspot therefore appears to be an important target in the formation of a fraction of meningiomas. In addition, 4 novel polymorphisms of INI1 were characterized. Our data indicate that the INI1 is a second tumour suppressor gene on chromosome 22 that may be important for the genesis of meningiomas.

Alleles↗
PubMed2001

Characteristics of 15,314 hypertensive patients at high coronary risk. The VALUE trial. The Valsartan Antihypertensive Long-term Use Evaluation.

Valsartan is an orally active, selective antagonist of the angiotensin II-1 (AT1) receptor developed for the treatment of hypertension. The Valsartan Antihypertensive Long-term Use Evaluation (VALUE) Trial of Cardiovascular Events in Hypertension is a double-blind, randomized prospective, parallel group study designed to compare the effects of valsartan with those of the calcium-antagonist amlodipine on the reduction of cardiac morbidity and mortality. Patients with essential hypertension, aged 50 years and older, and at particularly high risk of coronary events were enrolled. 18,119 patients were screened and 15,314 patients in 31 countries were randomized mainly between January 1998 and December 1999. These hypertensives had a mean blood pressure of 154.7/87.5 mmHg at the time of their randomization to blinded medication. The population comprises both genders (men 57.6%), Caucasians (89.1%), mean age 67.2 years, mean body mass index 28.6 kg/m2, coronary heart disease (45.8%), high cholesterol (33.0%), type 2 diabetes mellitus (31.7%) and smokers (24.0%). More than 92% of the randomized participants had been treated for high blood pressure for at least 6 months when screened for the study. The randomized population is now being treated (goal blood pressure < 140/90 mmHg) in adherence with the protocol until at least 1450 patients experience primary cardiac endpoint defined as clinically evident or aborted myocardial infarction, hospitalization for heart failure or death caused by coronary heart disease.

Aged↗
PubMed2001

Prevalence of HIV and hepatitis B and self-reported injection risk behavior during detention among street-recruited injection drug users in Los Angeles County, 1994-1996.

AIMS: To describe injection risk behaviors while in detention in a sample of injection drug users (IDUs) in Los Angeles County. DESIGN AND SETTING: Cross-sectional, interviewer-administered, face-to-face risk survey, and serological screening for HIV and hepatitis B conducted at four street locations in Los Angeles County between 1994 and 1996. All interviews were conducted in a non-institutionalized setting. MEASUREMENTS: Ascertainment of self-reported risk behavior during detention and screening for HIV and hepatitis B surface antigen (HBsAg) and antibody to the core (HBcAb) seromarkers. PARTICIPANTS: Six hundred and forty-two participants were street-recruited during the study period. Seventy-one per cent of the sample was male, the median age was 43 years, 61% were African-American, 27% were Latino, 8% were white and 36% considered themselves homeless. FINDINGS: Overall HIV prevalence was 3.0%; 3.1% tested positive for the hepatitis B surface antigen marker (HBsAg), and 80.3% for antibody to hepatitis B core antigen (HBcAb). After adjustment for length of injection drug use and recency of release from detention, HIV seroreactivity was significantly associated with history of detention due to possession of IDU paraphernalia (OR = 1.9). The presence of the hepatitis B HBcAb seromarker was associated with injection drug use while in detention, (OR = 1.7), and having been ever arrested for possession of IDU paraphernalia (OR = 1.8). CONCLUSIONS: IDU detainees constitute a high risk group for blood-borne infections. Comprehensive prevention and health promotion efforts in the community need to include correctional facilities.

AIDS Serodiagnosis↗
PubMed2001

In vitro synergy between cefepime and vancomycin against methicillin-susceptible and -resistant Staphylococcus aureus and Staphylococcus epidermidis.

The in vitro activity of cefepime combined with vancomycin was assessed by the chequerboard method against 35 clinical isolates of methicillin-susceptible (MSSA, n = 8) or -resistant (MRSA, n = 10) Staphylococcus aureus and methicillin-susceptible (MSSE, n = 9) or -resistant (MRSE, n = 8) Staphylococcus epidermidis and S. aureus ATCC 25923 (MSSA). The combination was synergic against 16 isolates and additive/indifferent against 20. For 10 of the clinical isolates (two MSSA, three MRSA, two MSSE, three MRSE) and the reference strain, the interaction of cefepime and vancomycin was also determined by the time-kill method. Except for one MRSA isolate, synergic killing was demonstrated with clinically achievable concentrations of vancomycin (0.5-1 mg/L) and cefepime (methicillin-susceptible isolates: 0.5-1 mg/L; methicillin-resistant isolates: 2-64 mg/L).

Anti-Bacterial Agents↗
PubMed2001

A novel class of amitogenic alginate microcapsules for long-term immunoisolated transplantation.

In the light of results of clinical trials with immunoisolated human parathyroid tissue Ba2+-alginate capsules were developed that meet the requirements for long-term immunoisolated transplantation of (allogeneic and xenogeneic) cells and tissue fragments. Biocompatibility of the capsules was achieved by subjecting high-M alginate extracted from freshly collected brown algae to a simple purification protocol that removes quantitatively mitogenic and cytotoxic impurities without degradation of the alginate polymers. The final ultra-high-viscosity, clinical-grade (UHV/CG) product did not evoke any (significant) foreign body reaction in BB rats or in baboons. Similarly, the very sensitive pERK assay did not reveal any mitogenic impurities. Encapsulated cells also exhibited excellent secretory properties under in vitro conditions. Despite biocompatible material, pericapsular fibrosis is also induced by imperfect capsule surfaces that can favor cell attachment and migration under the release of material traces. This material can interact with free end monomers of the alginate polymers under formation of mitogenic advanced glycation products. Smooth surfaces, and thus topographical biocompatibility of the capsules (visualized by atomic force microscopy), can be generated by appropriate crosslinking of the UHV/CG-alginate with Ba2+ and simultaneous suppression of capsule swelling by incorporation of proteins and/or perfluorocarbons (i.e., medically approved compounds with high oxygen capacity). Perfluorocarbon-loaded alginate capsules allow long-term non-invasive monitoring of the location and the oxygen supply of the transplants by using 19F-MRI. Transplantation studies in rats demonstrated that these capsules were functional over a period of more than two years.

Alginates↗
PubMed2001

Laboratory diagnosis of Clostridium difficile-associated diarrhea and colitis: usefulness of Premier Cytoclone A+B enzyme immunoassay for combined detection of stool toxins and toxigenic C. difficile strains.

Detection of Clostridium difficile toxins A and B in stools by Premier Cytoclone A+B enzyme immunoassay (EIA) was compared with detection by stool culture for C. difficile followed by detection of toxigenic isolates using the same EIA. Chart reviews were performed to evaluate the likelihood of C. difficile-associated diarrhea and colitis (CADC) for all patients with at least one positive toxin assay. While the toxins were detected in 58 of 85 consecutive CADC patients by both assays, CADC in 5 patients was detected only by stool toxin assay, and in 22 patients CADC was detected only by toxigenic culture. Our results suggest that for laboratories using a rapid toxin A+B EIA, direct toxin detection in stools should be combined with toxigenic culture in cases in which there is a negative stool toxin assay.

Bacterial Proteins↗
PubMed2001

Anterior versus posterior slippage: two different types of eccentric pouch dilatation in patients with adjustable laparoscopic gastric banding.

PURPOSE: To describe two different types of band dislocation that may occur in morbidly obese patients following adjustable laparoscopic gastric banding (ALGB) with the LAP-BAND. MATERIALS AND METHODS: 170 morbidly obese patients were treated with an LAP-BAND at our institution. In the first 20 patients the band was positioned transbursally, which means that the lesser sac is penetrated during laparoscopic band implantation. In the following 150 patients the operation technique was changed to suprabursal band positioning where the lesser sac is not penetrated. Plain radiographs and single contrast studies of all patients who developed band instability in the follow-up were analyzed retrospectively and compared to the clinical and intraoperative findings and to the operation technique used. RESULTS: Over a time period of 3.5 years 'posterior slippage' occurred in all 20 patients with transbursal band placement, but it never occurred after suprabursal band placement. Never- theless 4 patients with suprabursal band placement presented with an eccentric pouch dilatation, secondary to 'anterior slippage' after the seromuscular stitches had burst on the anterior and superior surface of the band. All these patients presented with food intolerance and all of them had to be reoperated. The radiographic findings were pathognomonic for each type of band dislocation. CONCLUSION: Band dislocation is a known major complication that may occur following ALGB and it may present in two different forms. While 'posterior slippage' can be avoided if the band is placed suprabursally, 'anterior slippage' may still occur. It is important to be familiar with both types of band dislocation since they require early detection and surgical band replacement or band refixation.

Body Mass Index↗
PubMed2001

A constrained EM algorithm for independent component analysis.

We introduce a novel way of performing independent component analysis using a constrained version of the expectation-maximization (EM) algorithm. The source distributions are modeled as D one-dimensional mixtures of gaussians. The observed data are modeled as linear mixtures of the sources with additive, isotropic noise. This generative model is fit to the data using constrained EM. The simpler "soft-switching" approach is introduced, which uses only one parameter to decide on the sub- or supergaussian nature of the sources. We explain how our approach relates to independent factor analysis.

Algorithms↗
PubMed2001

Anti-oxidized low-density-lipoprotein (OxLDL) antibodies in systemic lupus erythematosus with and without antiphospholipid syndrome.

The aim of this study was to examine potential links between antiOxLDL antibodies and the clinical and biological features of secondary antiphospholipid syndrome (II APLS) associated with systemic lupus erythematosus (SLE). A cohort study was done of 98 SLE patients followed-up for 1 y, including 18 with definite II APLS and 13 patients with definite primary APLS (I APLS). IgG anticardiolipin, IgG anti beta2 GPI, lupus anticoagulant, VDRL and IgG antiOxLDL were measured in all 98 study subjects. High antiOxLDL titers were found in seven (39%) of the 18 patients with II APLS vs 10 (12.5%) of the 80 patients without APLS (P < 0.01; OR = 4.45; 95% CI = 1.4-14.1) and none of the 13 patients with I APLS (P < 0.02). The mean antiOxLDL titer was not significantly higher in the SLE patients with than without II APLS (P > 0.05). A high antiOxLDL titer was correlated with deep venous thrombosis (P < 0.01; OR = 5.77; 95% CI = 0.54-61) but not with arterial thrombosis (P > 0.05; OR = 1; 95% CI = 0.29-3.09), thrombocytopenia, central nervous system involvement, livedo reticularis, or a positive Coombs test. The antiOxLDL antibody titer was correlated with the IgG anticardiolipin antibody titer (r = 0.235; P = 0.02) and with the IgG anti-beta2 GPI antibody titer (r = 0.224; P = 0.026). AntiOxLDL elevation was found in 17% of SLE patients and was significantly associated with II APLS and venous thrombosis. We found no evidence suggesting that antiOxLDL may be associated with atherosclerosis.

Adolescent↗