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Biomedical subjects

R Muller

Publications and source records attributed to R Muller.

At least 37 records · Page 2Linked to original sources
PubMed1997

Mapping of the mutations present in the genome of the Rift Valley fever virus attenuated MP12 strain and their putative role in attenuation.

The MP12 attenuated strain of Rift Valley fever virus was obtained by 12 serial passages of a virulent isolate ZH548 in the presence of 5-fluorouracil (Caplen et al., 1985. Mutagen-directed attenuation of Rift Valley fever virus as a method for vaccine development. J. Gen. Virol., 66, 2271-2277). The comparison of the M segment of the two strains has already been reported by Takehara et al. (Takehara et al., 1989. Identification of mutations in the M RNA of a candidate vaccine strain of Rift Valley fever virus. Virology 169, 452-457). We have completed the comparison and found that altogether a total of nine, 12 and four nucleotides were changed in the L, M and S segments of the two strains, respectively. Three mutations induced amino acid changes in the L protein but none of them was located in the recognized motifs conserved among RNA dependent polymerases. In the S segment, a single change modified an amino acid in the NSs protein and in the M segment, seven of the mutations resulted in amino acid changes in each of the four encoded G1, G2, 14 kDa and 78 kDa proteins. Characterization of the MP12 virus indicated that determinants for attenuation were present in each segment and that they were introduced progressively during the 12 passages in the presence of the mutagen (Saluzzo and Smith, 1990. Use of reassortant viruses to map attenuating and temperature-sensitive mutations of the Rift Valley fever virus MP-12 vaccine. Vaccine 8, 369-375). Passages 4 and 7-9 were found to be essential for introduction of temperature-sensitive lesions and attenuation. In an attempt to correlate some of the mutations with the attenuated or temperature-sensitive phenotypes, we determined by sequencing the passage level at which the different mutations appeared. This work should help to address the question of the role of the viral gene products in Rift Valley fever pathogenesis.

Animals↗
PubMed1997

Plasma lignocaine concentration following nebulization for awake intubation.

Nebulization of lignocaine is a common technique for preparing the airway prior to awake intubation. The aim of the study was to assay the serum levels of lignocaine. Ten ASA I volunteers had 6 mg/kg of 10% lignocaine solution nebulized via facemask. Blood assays for peak levels were performed. Mean peak serum lignocaine level was 0.29 mg/l with a highest measurement of 0.45 mg/l. This peak occurred 30 minutes following commencing nebulization. No subject developed symptoms or signs of lignocaine toxicity. Peak plasma lignocaine levels were an order of magnitude below the accepted toxic threshold of 5 mg/l. This indicates that supplemental doses of lignocaine via the bronchoscope can be given with safety.

Adult↗
PubMed1997

Timed ELISA: an alternative approach to quantitative enzyme-linked immunosorbent assay.

As the uses for ELISA (enzyme-linked immunosorbent assay) increase, so does the need for a quantitative procedure that does not require a spectrophotometer or other expensive equipment. 'Timed ELISA' employs an 'iodine clock' as the final step such that quantitative measurements may be made using a stopwatch. Catalase, coupled to the primary antibody, reduces the concentration of H2O2 available to generate iodine in the clock reaction. Iodine stains the starch component blue, but catalase prolongs the time taken for the change in colour to be observed. After the time delay occurs the transition to full colour development is extremely rapid (< 1 s) at all analyte concentrations, allowing clear definition of the end point. The performance of Timed ELISA is similar to that obtained using a horseradish peroxidase-conjugated system employing the customary spectrophotometric determination.

Biotechnology↗
PubMed1996

Prophylactic application of thyrostatic drugs during excessive iodine exposure in euthyroid patients with thyroid autonomy: a randomized study.

In a prospective, randomized study we examined the influence of prophylactic short-term thyrostatic therapy on thyroid iodine metabolism in patients with euthyroid autonomy undergoing elective coronary angiography. From a total of 1177 patients, 51 fulfilled the criteria of euthyroid autonomy before coronary angiography (negative thyrotropin-releasing hormone test, 10-min uptake of at least 1.2%, 99mTc and no elevation of free thyroxine and free triiodothyronine indices) and were randomized into three groups: group 1 (N = 17) received 20mg/day of thiamazole and group 2 (N = 17) received 900 mg/day of sodium perchlorate; thyrostatic therapy was begun on the day before angiography and continued for 14 days; group 3 (N = 17) served as controls without treatment. Parameters of thyroid function-free thyroxine (FT4) index and free triiodothyronine (FT3) index, thyrotropin (TSH) and delta-TSH urine iodine excretion and 99mTc uptake were determined before and 30 days after coronary angiography. At the end of the study the mean FT4 index and FT3 index were elevated significantly in the control group compared with baseline values, but were still within the normal range. In contrast, the mean FT4 index and FT3 index remained unchanged in the treated groups. Four mild cases of hyperthyroidism were observed at the end of the study: two cases in the control group and one case in each of the treated groups. Thyrotropin suppression, urine iodine excretion and 99mTc uptake differed significantly between the treated groups and the control group. In the treated groups TSH suppression, urine iodine excretion and 99mTC uptake remained unchanged 30 days after coronary angiography compared with baseline values. In the control group the degree of TSH suppression and the level of urine iodine excretion increased (about twofold) significantly after coronary angiography, whereas 99mTc uptake decreased significantly (ca. 50%). In conclusion, short-term prophylactic thyrostatic therapy seems to have a protective effect against iodine excess in patients with euthyroid autonomy. However, mild hyperthyroidism could not be prevented in some cases. Probably a combination therapy of thiamazole and perchlorate would be more effective.

Aged↗
PubMed1995

Relationship of interleukin-1 receptor antagonist to mucosal inflammation in inflammatory bowel disease.

Previous work has suggested that the interleukin-1 (IL-1) receptor antagonist, IL-1ra, may regulate mucosal inflammation in inflammatory bowel disease. The present study assessed the relationship of mucosal IL-1ra levels to histologic severity of inflammation and the related proinflammatory cytokines IL-1 beta and IL-6 in children with inflammatory bowel disease. Colonic biopsy specimens from 29 patients with ulcerative colitis, 27 with Crohn's disease, and 24 noninflammatory control subjects were assayed for IL-1ra, IL-1 beta, and IL-6 by enzyme-linked immunosorbent assay. Histologic activity was graded as none, mild, moderate, or severe. Mucosal IL-1 beta levels, but not IL-1ra levels, were significantly elevated in moderate/severely inflamed biopsies from patients with either ulcerative colitis (p < 0.01) or Crohn's disease (p < 0.001) compared with those with none/mild inflammation. The mucosal molar ratio of IL-1ra/IL-1 beta was significantly lower for moderate/severe inflammation compared with none/mild inflammation for patients with ulcerative colitis (p < 0.05) and Crohn's disease (p < 0.01). The mucosal IL-1ra/IL-1 beta ratio was similar in controls to none/mild inflamed biopsies from subjects with either ulcerative colitis or Crohn's disease. Our observations suggest that increasing mucosal inflammation in inflammatory bowel disease in children is associated with a decrease in the "normal" effective IL-1ra/IL-1 beta ratio in which IL-1ra predominates. The importance of this abnormality to the pathogenesis of inflammatory bowel disease awaits further study.

Adolescent↗
PubMed1995

Abdominal compartment syndrome.

Abdominal compartment syndrome is still a controversial entity. We report on a patient who developed the classical hemodynamic, respiratory, and renal changes of abdominal compartment syndrome after surgical intervention for blunt abdominal trauma. A decompressive laparotomy improved the situation dramatically.

Abdominal Injuries↗
PubMed1995

The L protein of Rift Valley fever virus can rescue viral ribonucleoproteins and transcribe synthetic genome-like RNA molecules.

Overlapping cDNAs representing the complete L segment of Rift Valley fever virus were assembled, and the L protein was expressed via a recombinant vaccinia virus. The transcriptase activity of the L protein was assayed with two types of templates: natural ribonucleoproteins (RNPs) and artificial genome-like RNAs. RNPs purified in a CsCl gradient did not retain the RNA polymerase function, but the activity was restored when the L cDNA was expressed in mammalian cells via a recombinant vaccinia virus. Indeed, after transfection of transcriptase-depleted RNPs in cells infected with the recombinant vaccinia virus expressing the L protein, the mRNAs coding for the N and NSs proteins and to a lesser extent, those coding for the glycoproteins were synthesized as well as the corresponding proteins. The transcriptase activity of the recombinant L protein was then investigated by using synthetic templates containing the reporter chloramphenicol acetyltransferase gene in the antisense orientation flanked by the 3' and 5' noncoding region of the S genomic segment. Our results indicate that after transfection of the RNA templates, transcription was achieved in cells coexpressing both the L and N proteins. Together, the experiments demonstrate that the two proteins N and L are absolutely required and sufficient to reconstitute the transcriptase activity.

Base Sequence↗
PubMed1995

Characterization of clone 13, a naturally attenuated avirulent isolate of Rift Valley fever virus, which is altered in the small segment.

The 74HB59 strain of Rift Valley fever (RVF) virus, isolated from a human case in the Central African Republic, was shown to be composed of a heterogeneous population of viruses when plaque-purified clones were analyzed for their reactivity with monoclonal antibodies (MAbs) directed against the nucleocapsid (N) protein or the nonstructural (NSs) protein. One of these clones, C13, was of particular interest in that it proved to be avirulent in mice and hamsters, and highly immunogenic. Although C13 showed normal reactivity with a large panel of MAbs directed at the glycoproteins, it failed to react with specific MAbs or polyclonal antibodies directed at the NSs protein and with a specific MAb recognizing the N protein of the Egyptian strains. Consequently, the small RNA segment, which encodes the N and NSs proteins in an ambisense strategy, was sequenced and compared with the existing sequence of the attenuated MP-12 RVF virus strain. We found that the NSs gene contained, in addition to two conservative coding changes, a large internal deletion of 549 nucleotides that removes 69% of the open reading frame but conserves in-frame the N and C termini of the predicted translation product. In addition, the sequence revealed that the N protein of C13 contained a single amino acid change. Clone C13 replicated normally in certain cell types in vitro and in Culex pipiens mosquitoes after intrathoracic inoculation, but established abortive infections in MRC-5 human fibroblasts.

Animals↗
PubMed1994

Molecular cloning and nucleotide sequence of the coat protein gene of a Cuban isolate of potato leafroll virus and its expression in Escherichia coli.

Total RNA from infected Physalis floridana was isolated to generate complementary DNA corresponding to the coat protein (GP) gene of a Cuban isolate of potato leaf roll virus (PLRV). This cDNA was amplified by the polymerase chain reaction (PCR) and cloned into the bacterial expression vectors pEX(1-3) for fusion protein expression in E. coli. The product was detected by antibodies specific for the PLRV CP. The coding sequence of the CP gene was determined, and the predicted length of the CP was 208 amino acids (23 kD). The nucleotide sequences and deduced amino acid sequences were compared with the other PLRV isolates and found to be 97-99.5% identical at both the nucleotide and amino acid sequence level of other isolates. Comparison of the deduced amino acid sequences of the PLRVcub CP revealed considerable homology to other luteoviruses. We believe that the protocol described could be applicable to other plant viruses of low abundance or of cumbersome isolation, since this method is less time consuming than the traditional methods of cloning coat protein genes of plant viruses with known sequences.

Amino Acid Sequence↗
PubMed1993

Liver transplantation in European patients with the hepatitis B surface antigen.

BACKGROUND: The role of liver transplantation in patients positive for the hepatitis B surface antigen (HBsAg) is controversial because of the high rate of recurrent hepatitis B virus (HBV) infection. It has not been determined whether this risk is greater for certain patients and whether the administration of anti-hepatitis B surface antigen (anti-HBs) immune globulin is beneficial. METHODS: We conducted a retrospective study at 17 European centers of 372 consecutive HBsAg-positive patients who underwent liver transplantation between 1977 and 1990. Recurrence of HBV infection was defined as the reappearance of HBsAg in serum. RESULTS: For all 334 patients with follow-up data, the mean (+/- SE) three-year actuarial risk of recurrence of HBV was 50 +/- 3 percent. The risk was 67 +/- 4 percent among 163 patients with HBV-related cirrhosis, 32 +/- 5 percent among 110 patients with cirrhosis related to hepatitis delta virus, 40 +/- 16 percent among 14 patients with fulminant hepatitis delta infection, and 17 +/- 7 percent among 39 patients with fulminant HBV infection (P < 0.001). Among the patients with HBV-related cirrhosis, the risk of HBV recurrence was greatest (83 +/- 6 percent) in those who were seropositive for HBV DNA at the transplantation and lowest (58 +/- 7 percent) in those with neither HBV DNA nor hepatitis B e antigen detectable in serum. With respect to the use of passive prophylaxis with anti-HBs immune globulin, the risk of HBV recurrence was 75 +/- 6 percent among the 67 patients given no immunoprophylaxis, 74 +/- 5 percent among the 83 treated for two months, and 36 +/- 4 percent among the 209 treated for six months or longer (P < 0.001). In a multivariate analysis the predictors of a lower risk of HBV recurrence were the long-term administration of the immune globulin, hepatitis delta virus superinfection, and acute liver disease. For the entire study cohort, survival was 75 percent at one year and 63 percent at three years, but for those in whom HBV infection recurred, survival was 68 percent at one year and 44 percent at three years. CONCLUSIONS: In this retrospective study of HBsAg-positive patients, liver transplantation had better results in those who had fulminant hepatitis or delta virus superinfection. An absence of viral replication at the time of transplantation and long-term immunoprophylaxis were associated with a reduced risk of recurrent HBV infection and reduced mortality.

Actuarial Analysis↗
PubMed1993

Interactions of bupranolol with the polymorphic debrisoquine/sparteine monooxygenase (CYP2D6).

The beta-adrenoceptor blocker bupranolol turned out to be a competitive inhibitor of the polymorphic cytochrome P450 CYP2D6 of which sparteine is a substrate. There was stereo-selectivity of bupranolol involved: (-)-bupranolol was the weakest inhibitor with an apparent Ki value of 1.32 microM, (+)-bupranolol was the most potent with an apparent Ki value of 0.55 microM, while the therapeutically used racemic bupranolol had an intermediate value of 0.88 microM. A 10 min pre-incubation of 5 microM bupranolol with the enzyme preparation prior to the addition of substrate, reduced the inhibition of sparteine metabolism from 52 to about 25%. This suggests that--during these inhibition studies--bupranolol was much more rapidly metabolized than was sparteine, so that the measured Ki values must represent overestimates. The enzyme catalysing bupranolol metabolism was CYP2D6: microsomes from a liver with the genetic enzyme deficiency did not metabolize bupranolol; in microsomes from livers containing the enzyme and 10 microM bupranolol, 5 microM quinidine caused a 72% inhibition of bupranolol metabolism. Although our methods were not sufficiently sensitive to measure the Km of bupranolol directly, it is undoubtedly the beta-adrenoceptor blocker with the highest-known apparent affinity for CYP2D6. High affinity and rapid metabolism are infrequent combinations in enzymology.

Binding, Competitive↗
PubMed1992

Intraductal carcinoma of major salivary gland.

The clinicopathologic features of the cases of three patients with intraductal carcinoma of major salivary gland are described. As in the breast, these lesions of salivary ducts appear to represent an in situ or preinvasive phase of the disease. On follow-up, one patient had a local recurrence, and in another patient, the tumor subsequently became invasive. This experience suggests that wide surgical excision (preferably total parotidectomy) may be curative but that resections limited to grossly visible disease will result in local recurrence and/or the development of invasive ductal adenocarcinoma.

Adenocarcinoma↗
PubMed1992

[Ambulatory phlebectomy].

Ambulatory phlebectomy has been done already in Greek and Roman times. It was since forgotten for many centuries, but it has been revived by Müller in 1956. Ambulatory phlebectomy is one of the most rewarding instances of ambulatory surgery. It consists of the comprehensive extraction of the varices through extremely small stab incisions, followed immediately by vigorous marching. It calls for team work: The surgeon performs the high ligation and stripping of the proximal third of the greater saphenous vein, and the phlebologist removes all the other varices. And it is an almost ideal treatment, as it provides efficiency as well as excellent cosmetic results at low costs and is also harmless.

Ambulatory Surgical Procedures↗