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Biomedical subjects

M Felder

Publications and source records attributed to M Felder.

At least 19 recordsLinked to original sources
PubMed2005

The genome of the social amoeba Dictyostelium discoideum.

The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.

ATP-Binding Cassette Transporters↗
PubMed2004

A randomized trial of prolonged high dose of interferon plus ribavirin for hepatitis C patients nonresponders to interferon alone.

Retreatment of chronic hepatitis C patients nonresponders to interferon (IFN) alone with the standard dose of IFN [3 million units (MU) thrice weekly (TIW)] plus ribavirin for 24 weeks has yielded low sustained virological response (SVR), averaging 8%. The aim of the present, open-labelled, randomized study was to evaluate the efficacy of IFN induction therapy followed by prolonged high dose of IFN plus ribavirin in nonresponders. One hundred and fifty-one patients were randomized to receive 5 MU daily of IFN alfa-2b (group 1, n = 73) or 5 MU TIW of IFN alfa 2b (group 2, n = 78) for 4 weeks followed by IFN (5 MU TIW) plus ribavirin (1000/1200 mg/daily) for 48 weeks in both groups. In an intention-to-treat analysis, the sustained virological response (SVR) at 24-week follow-up was 33 and 23% for group 1 and 2, respectively (P = 0.17). The overall SVR was 52 and 18% in patients with genotype 2/3 and 1/4, respectively. Among genotype 1/4 patients the SVR was 29 and 11% for age younger or older than 40 years. Compared with genotype 2/3 patients, the risk (95% confidence interval) of nonresponse to retreatment was 3.0-fold (1.17-8.0) in younger genotype 1/4 patients and 8.4-fold (3.0-23.29) in older genotype 1/4 patients. In conclusion these results suggest that retreatment with a reinforced regimen should be focused in nonresponder genotype 2/3 patients and younger genotype 1/4 patients, who are most likely to benefit. Induction therapy does not improve SVR.

Adult↗
PubMed2003

Efficacy of prolonged 5 million units of interferon in combination with ribavirin for relapser patients with chronic hepatitis C.

summary. Retreatment of relapser patients with chronic hepatitis C with the standard dose of interferon (IFN) of 3 million units (MU) thrice weekly (tiw) plus ribavirin for 24 weeks achieves a sustained response in 30 and 73% of patients with genotype 1 and 2 or 3, respectively. The aim of this study was to evaluate the efficacy and safety of IFN alpha-2b induction therapy, followed by prolonged treatment with a high dose of IFN alpha-2b plus ribavirin in relapser patients. A total of 119 patients were randomized to receive IFN alpha-2b 5 MU daily (Group A: 59 patients) or IFN alpha-2b 5 MU tiw (Group B: 60 patients) for 4 weeks followed by IFN (5 MU tiw) and ribavirin (1000-1200 mg/day) for 48 weeks in both groups. The primary end point was hepatitis C virus (HCV)-RNA clearance at week 24 after the end of treatment. A sustained virological response (SVR) was achieved in 68 and 60% of Group A and B patients, respectively (P = 0.37). Logistic regression analysis identified genotype 2 or 3 as the only independent factor associated with response, whereas induction regimen and baseline viraemia levels did not affect the response. The overall SVR was 53 and 72% in patients with genotype 1 or 4 and 2 or 3, respectively. In conclusion, induction IFN therapy does not enhance the SVR to a 48-week combination therapy. Our study suggests that relapsed patients with genotype 1 or 4 may achieve significant response rates of approximately 50%, if retreated with 5 MU tiw IFN plus ribavirin for 48 weeks.

Adult↗
PubMed2002

Tamoxifen in the treatment of hepatocellular carcinoma: 5-year results of the CLIP-1 multicentre randomised controlled trial.

BACKGROUND: In 1998, when data of a meta-analysis on tamoxifen in the treatment of hepatocellular carcinoma (HCC) had suggested a little advantage for this treatment, we published the results of a multicenter randomised controlled trial, that showed no survival benefit for tamoxifen vs. control. Here we report an updated analysis of the study results 4.5 years after the closure of enrollment. METHODS: The study had a planned sample size of 480 patients. Patients with any stage HCC were eligible, irrespective of locoregional treatment. Tamoxifen was given orally, 40 mg/die, from randomisation until death. RESULTS: 496 patients were randomised by 30 Institutions from January 1995 to January 1997. Information was available for 477 patients. As of July 2001, 374 deaths (78%) were recorded, and median survival times were 16 and 15 months (p=0.54), in the control and tamoxifen arm. Data were further analysed separately for advanced patients and for those eligible to potentially curative locoregional treatments: relative hazard of death for patients receiving tamoxifen was equal to 0.98 (95% CI 0.76-1.25) for the former group and 1.38 (95% CI 0.95-2.01) for the latter. The prognostic score recently devised by our group (CLIP score) was, as expected, strictly correlated (p<0.0001) to the locoregional treatment received and strongly correlated with prognosis. CONCLUSIONS: the update of the present study confirms that tamoxifen is not effective in prolonging survivals, both in advanced patients and in those potentially curable and that the CLIP score is able to predict prognosis.

Carcinoma, Hepatocellular↗
PubMed2001

Identification and expression of cosmids with an allelic variant of class I alcohol dehydrogenase in transgenic mice.

The mouse Adh1 gene exhibits tissue-specific regulation, is developmentally regulated, and is androgen regulated in kidney and adrenal tissue. To study this complex regulation phenotype a transgenic mouse approach has been used to investigate regulatory regions of the gene necessary for proper tissue expression and hormonal control. Transgenic mice have been produced with an Adh1 minigene as a reporter behind either 2.5- or 10 kb of 5'-flanking sequence [1]. Complete androgen regulation in kidney requires a region between -2.5 and -10 kb. A sequence extending to -10 kb does not confer liver expression in this minigene construct. B6.S mice express an electrophoretically variant protein resulting from a known nucleotide substitution resulting in a restriction endonuclease length polymorphism. Transgenic mice harboring B6.S cosmids can be studied for expression analysis at both protein and mRNA levels, identification of transgenic founders and inheritance studies are greatly facilitated by a PCR-restriction endonuclease cleavage approach, the entire mouse gene is used as a reporter, and the formation of heterodimeric enzyme molecules can be used to infer expression of the transgene in the proper cell types within a given tissue. Expression of a B6.S cosmid containing the entire Adh1 gene and 6 kb of 5'- and 21 kb of 3'-flanking region occurs in transgenic mice in a copy number dependent manner in a number of tissues, but expression in liver does not occur. The ability to analyze expression at the protein and mRNA levels has been confirmed using this system. Future directions will involve the use of large BAC clones modified by RARE cleavage to identify the liver specific elements necessary for expression.

Alcohol Dehydrogenase↗
PubMed2000

The pyrroloquinoline quinone synthesis genes of Gluconobacter oxydans.

A Tn5-induced glucose dehydrogenase (GDH) deficient mutant of Gluconobacter oxydans IFO 3293 was characterised. DNA sequencing showed that the insertion site occurred in an open reading frame with homology to the pqqE gene. It was shown that acid production could be restored by addition of the coenzyme pyrroloquinoline quinone (PQQ) to the medium. The pqq cluster of G. oxydans ATCC 9937 was cloned and sequenced. It has five genes pqqA-E. The cluster could complement the Tn5-induced mutation in IFO 3293. Pulsed-field gel electrophoresis suggested that the pqq genes are not closely linked to the ribF gene that produces the riboflavin cofactor for the gluconic acid dehydrogenase.

Bacterial Proteins↗
PubMed2000

[Value of ultrasound study and dual energy x-ray absorptiometry (DEXA) for assessment of risk of osteoporosis].

UNLABELLED: Screening postmenopausal women for preventing osteoporosis at an early stage is the main topic of several studies. The present paper evaluates the place of ultrasound measurements in comparison with Dual Energy X-ray-absorptiometry (DEXA). METHODS: 247 women (41 women < or = 50 yrs, 103 women 50-60 yrs, 103 women > 60 yrs) underwent DEXA of the vertebrae and hip and concommittantly ultrasound measurements of the calcaneus. RESULTS: The DEXA values in the vertebral column vary considerably and are lowest in L1 and highest in L4. The femur on the other hand shows lowest values in the Ward triangle (T = -1.6 SD), and highest in the trochanter (T = -0.3 SD). Speed of sound (SOS) gives lower T-values (-1.2 SD) than broadband ultrasound attenuation (BUA) (-0.3 SD). Statistical analysis (Spearman, Pearson) shows no correlation between ultrasound and DEXA measurements and therefore do not permit analogies between hip and vertebral column and vice versa. CONCLUSIONS: Our data show that the fracture risk of an individual woman can be adequately ascertained only by DEXA-measurement of vertebrae and femur. Ultrasound measurement today cannot be recommended as routine screening or diagnostic method.

Absorptiometry, Photon↗
PubMed2000

Long-term results of a clinical trial of nadolol with or without isosorbide mononitrate for primary prophylaxis of variceal bleeding in cirrhosis.

It is clearly established that beta-blockers decrease the risk of a first variceal bleeding in cirrhosis. We have recently shown that the addition of isosorbide mononitrate to nadolol decreases the rate of variceal bleeding in patients with cirrhosis and varices, compared with nadolol alone, after a median follow-up of 30 months. It is not established if the long-term treatment with the combination continues to be beneficial. Therefore, we assessed the long-term effect of this combination on first variceal bleeding, complications, and death. One hundred forty-six cirrhotic patients with esophageal varices included in a previously published multicenter, randomized study comparing nadolol (40-160 mg/d) with the combination nadolol plus isosorbide mononitrate (10-20 mg 3 times per day) were followed up for up to 7 years (median follow-up, 55 months). The primary end-point was variceal bleeding of any severity. Twenty-four patients (16 in the nadolol group, and 8 in the combination group) experienced variceal bleeding (log rank test, P =.02). Cumulative risk of bleeding was 29% and 12%, respectively (95% CI for the difference, 1%-23%). Two and 4 patients, respectively, had bleeding from portal hypertensive gastropathy (log rank test, P =.20). Thirty and 25 patients, respectively, died during follow-up (log rank test, P =.13). Twelve and 10 patients, respectively, had de novo occurrence of ascites during follow-up (log rank test, P =.29). In conclusion, nadolol plus isosorbide mononitrate is significantly more effective than nadolol alone in the long-term use. Side effects are few, and no deleterious effects on ascites occurrence or on survival occur after long-term use of this combination.

Adolescent↗
PubMed1999

A mutant of gluconobacter oxydans deficient in gluconic acid dehydrogenase

Gluconobacter oxydans ATCC 9937 was subjected to transposon mutagenesis using Tn5. A non-pigmented mutant was shown to be defective in gluconic acid dehydrogenase and to produce gluconic acid from glucose, whereas the parent strain produced 2, 5-diketogluconic acid. Cloning and sequencing of the region containing the Tn5 insertion showed that the insertion point occurred in an open reading frame homologous (42% amino acid identity) to the ribF genes of Pseudomonas fluorescens and Escherichia coli. The resulting lack of a riboflavin cofactor would explain the loss of enzyme activity.

Journal Article↗
PubMed1998

[Pharmacologic pain treatment].

Pharmacotherapy of chronic pain uses the following groups of drugs: simple analgesics, NSAID's, opioids, calcitonin, antidepressants, neuroleptic drugs and myorelaxants. Diseases of the locomotor system are very often chronic or chronically recurrent. We therefore need a tailored longterm therapy. We have to consider not only the effect but also side effects of the different drugs. The aim of the therapy is an optimal quality of life for the individual patient. To this end we have to avoid polypragmasia.

Analgesics↗
PubMed1996

Extracorporeal shock wave lithotripsy (ESWL) of gallbladder stones: experience in Bolzano.

During a period of 24 months, 115 patients with symptomatic gallbladder stones (77 females, 38 males; median age 46 years, range 22-87) were treated by extracorporeal shock wave lithotripsy with a Lithostar Plus. Concomitant bile acid dissolution therapy (ursodeoxycholic acid + chenodeoxycholic acid 7.5 mg/kg/day each or tauroursodesoxycholic acid 5-10mg/kg/day) was administered until 3 months after total fragment clearance. Complete clearance of all fragments was obtained after 6, 9, 12, 18 and 24 months in, respectively, 30, 45, 51, 62 and 72%. Life table analysis of the subgroups showed significantly better clearance results in patients with fragments < 5mm at the first extracorporeal shock wave lithotripsy session (67%) than in patients with larger fragments (39%) (p < 0.01). Patients with solitary stones < 20mm cleared their fragments better (58%) at 12 months than those with multiple stones (49%), but the differences were not statistically significant. Stone recurrence was 6% at 1 year and was lower in patients with solitary stones (3%) than in those with multiple stones (12%). Major side effects consisted in 2 cases of mild acute pancreatits and 19% of biliary colics.

Cholelithiasis↗
PubMed1996

[The medical therapy of chronic pancreatitis. Problems, progress and outlook].

The aims of medical therapy in chronic pancreatitis are mainly to relieve the recurrent pain and to correct any malabsorption secondary to digestive insufficiency resulting from deficient exocrine pancreatic function. The treatment of the pain initially involves the use of dietary measures and analgesic drugs. The results of the use of pancreatic extracts and somatostatin reported in the literature are controversial, as are those of coeliac plexus block. Of unquestionable efficacy, at least in the short to medium term, are surgical decompression interventions in patients, with pain refractory to these measures and who present significant dilation of Wirsung's duct at ERCP. Endoscopic decompression constitutes an alternative to surgical decompression. In view of the transitory results of endoscopic decompression, which, in any event, should be implemented only by endoscopists possessing the necessary experience and expertise, the use of this technique may perhaps be targeted at carefully selected patients to be submitted to surgical decompression. As far as maldigestion is concerned, which occurs only when the pancreatic functional deficit reaches 90% or more, replacement therapy with pancreatic extracts must be resorted to. Multi-Unit Dose preparations are to be preferred, consisting in gastro-protected microspheres measuring not more than 2 mm in diameter and containing high doses of lipase, since at least 30,000 I.U. of lipase are required in the post-prandial phase for reasonably satisfactory correction of the steatorrhoea. Should this fail to prove effective, it is good policy to add antisecretory drugs (H2-antagonists, proton-pump inhibitors).

Chronic Disease↗
PubMed1994

Characterisation of plasmids from diketogluconic acid producing strains of Gluconobacter oxydans.

Gluconobacter oxydans ATCC 9937, which produces 2,5-diketogluconic acid, an intermediate in vitamin C synthesis, has three plasmids of sizes 27.7 kb (pVJ1), 12.3 kb (pVJ2) and 18 kb (pVJ4). A restriction map was constructed of pVJ1. A potential glucose dehydrogenase gene was located on pVJ1 using the polymerase chain reaction with heterologous primers. Two other G. oxydans strains had no detectable plasmid DNA (IFO 12258) and a plasmid (pVJ3) of 9.4 kb (IFO 3293), respectively.

Base Sequence↗
PubMed1994

Turning of nerve growth cones induced by neurotransmitters.

Pathfinding by growing nerve processes in the developing nervous system depends on the turning response of the growing tip, the growth cone, to extracellular guidance cues. There is evidence in vivo and in cell culture that some growth cones exhibit chemotropic behaviour, but the identity of endogenous chemoattractants remains elusive. Neurotransmitters appear early in the developing embryo and may have morphogenic roles in development. In cell culture a number of neurotransmitters were found to induce growth inhibition or retraction of neurites. Here we report positive turning responses of the nerve growth cone in a defined extracellular gradient of the neurotransmitter acetylcholine (ACh). The growth cone response depends on the activation of neuronal nicotinic ACh receptors, requires the presence of extracellular Ca2+, and appears to be mediated by Ca(2+)-calmodulin-dependent protein kinase II. Fluorescence imaging of cytosolic Ca2+ concentration ([Ca2+]i) at the growth cone showed a small but significant evaluation of [Ca2+]i within minutes of the onset of ACh application and before the turning of the growth cone. These findings suggest that neurotransmitters may serve as specific chemoattractants for growth cone guidance and that cytosolic Ca2+ may act as a second messenger in the cytoplasm of the growth cone to initiate the turning response.

Acetylcholine↗