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Biomedical subjects

H M Müller

Publications and source records attributed to H M Müller.

At least 55 records · Page 3Linked to original sources
PubMed1997

Natural occurrence of Fusarium toxins in barley harvested during five years in an area of southwest Germany.

A total of 44, 40, 47, 51, and 58 barley samples for feed use were collected randomly after the 1987, 1989, 1990, 1991, and 1992 crops, respectively, from farms located in an area of southwest Germany. The sum of precipitation from May to September was high in 1987 and markedly lower in 1989-1992. Deoxynivalenol, 3-. and 15-acetyldeoxynivalenol, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin and diacetxyscirpenol were determined by gas chromatography with mass selective detection (GC-MS), zearalenone,alpha- and beta-zearalenol by GC-MS or by HPLC. Deoxynivalenol was the major toxin with incidences at 71-98% and mean contents at 42-400 microg/kg. In contrast, incidences of zearalenone, 3-acetyldeoxynivalenol, nivalenol, HT-2 toxin, and T-2 toxin were at 7-68, 7-48, 11-41, 0-9, and 2-29%, respectively; with mean contents at 3-146 microg/kg. alpha- and beta-zearalenol and diacetoxyscirpenol were not detected in any sample. 15-acetyldeoxynivalenol and fusarenon-X were assayed in samples from 1987, 1991 and 1992. 15-acetyldeoxynivalenol was detected in 30, 0 and 2% of samples, respectively, with an average content of positive samples at 8 and 4 microg/kg, fusarenon-X was not detected. Over the years, incidences and levels of toxins remained constant, decreased or increased. The correlation between the occurrence of toxins and level of precipitation is discussed.

Journal Article↗
PubMed1997

Formation and disappearance of mycophenolic acid, patulin, penicillic acid and PR toxin in maize silage inoculated with Penicillium roqueforti.

Maize silage was inoculated with Penicillium roqueforti strains which are able to form the mycotoxins mycophenolic acid (MPA), patulin (PAT), penicillic acid (PA), or PR toxin (PRT). The silage was incubated for 160 d without agitation under aerobic conditions at 15 degrees C in the dark. The mycotoxins were quantified by HPLC and identified by HPLC combined with diode array detection and by two-dimensional thin layer chromatography. MPA, PAT, PA, and PRT above the detection limit were measured for the first time at 36, 22-27, 13, and 49 days of incubation, maximum toxin contents (mg/kg) were 3.56 MPA, 15.10 PAT, 3.06 PA, and 2.17 PRT. With increasing storage time toxin contents decreased to a low or non detectable level. The production of MPA, PAT and PRT was preceded by an increase in pH from 4 to 8-9. Along with the initial pH increase the content of ergosterol as well as of P. roqueforti and yeast propagules increased whereas the levels of total soluble sugar and of water extractable NH3 decreased. It is concluded that the probability to detect MPA, PAT, PA, and PRT in maize silage moulded by P. roqueforti under practical conditions of agriculture is low during the growth of this fungus and again after prolonged storage.

Animals↗
PubMed1997

Balloon dacryocystoplasty: indications and contraindications.

PURPOSE: To define the indications and contraindications for balloon dacryocystoplasty. MATERIALS AND METHODS: Eighty-five patients with severe epiphora due to partial (n = 47) or complete (n = 38) obstruction of the nasolacrimal duct (NLD) were treated with balloon dacryocystoplasty (DCP). Steerable micro-guide wires with flexible tips were used. Success rates of DCP were evaluated clinically and dacryocystographically during the acute phase and at 6- and 12-month follow-up. Failures and recurrences were correlated with clinical and dacryocystographic indications for treatment. RESULTS: Recanalization was successful in 35 (92%) of 38 patients with isolated focal stenoses (n = 20) or short-distance occlusions (n = 18) of the NLD. Among all 85 patients, recanalization was successful in 25 patients (66%) with complete and 37 patients (79%) with partial obstructions. In the absence of the main predictors for recurrent obstructions (ie, active inflammation, filling defects due to calculi, long-distance occlusions, and posttraumatic lesions), 12-month patency rates were 89% (17 of 19 focal stenoses) and 94% (15 of 16 focal occlusions). Otherwise, reobstruction rate was 46% (12 of 26 cases). CONCLUSION: Balloon dacryocystoplasty is successful only in select cases. To achieve results comparable to those of operative treatment, the indication should be limited to patients with circumscribed focal stenoses or occlusions of the NLD. Active dacryocystitis, dacryocystolithiasis, and posttraumatic lesions are the main contraindications.

Catheterization↗
PubMed1997

Recurrent hepatitis C virus infection after liver transplantation--long-term follow-up with respect to the HCV genotypes/subtypes.

BACKGROUND/AIMS: Various factors may affect the postoperative course in recurrent hepatitis C virus (HCV) infection after liver transplantation (OLT). The aim of our study was to evaluate the potential role of HCV genotypes and immunosuppressive treatment. METHODS: 17 liver allograft recipients, HCV-RNA positive prior to OLT, were followed 26-102 months postoperatively. The diagnosis of HCV infection was based on clinical, serological and histological findings and detectable HCV-RNA in serum. The genotypes/subtypes were evaluated by a "reverse line probe" assay. RESULTS: After OLT hepatitis C viremia was evident in 16 of 17 allograft recipients (94%). Two patients acquired HCV infection after transplantation (incidence 0.84%). Clinically eight of 18 viremic patients remained asymptomatic. Ten of 18 had an acute hepatitis (eleven to 27 weeks after OLT), of those nine patients developed chronic hepatitis (hepatic activity indices: grade 1-3) with progression to fibrosis in two patients. One patient subsequently developed cirrhosis. Subtype 1 b was predominant (eleven of 18 patients). After transplantation subtype 1 b was not associated with a higher rate of recurrent hepatitis compared to other genotypes/subtypes (45% in type 1 b vs. 71% in type "non-1 b"; n.s.). CONCLUSION: Identical HCV genotypes/subtypes before and after OLT indicate a recurrent rather than a postoperatively acquired HCV infection of the allograft. Despite viremia most patients had no or mild to moderate hepatitis in the long-term follow-up. Different HCV genotypes were not associated with specific clinical courses of recurrent HCV infection after OLT.

Adolescent↗
PubMed1996

What's in a name? Electrophysiological differences between spoken nouns, proper names and one's own name.

To investigate the neural processing of different word categories, we recorded event-related potentials (ERPs) from 32 individuals listening to sentences, beginning either with a proper name (first name), the subject's own name, or a common noun. Names and nouns both elicited ERP waveforms with the same early componentry, but the N1 and P2 components were larger for proper names than common nouns. The ERPs to the subject's own name also had a large N1/P2 plus a prominent negativity at parieto-central site peaking around 400 ms and a late positivity between 500-800 ms over left lateral-frontal sites. These findings are consistent with differential processing of people's first names within the category of nouns.

Acoustic Stimulation↗
PubMed1996

Conserved function of anopheles gambiae midgut-specific promoters in the fruitfly.

Control of malaria by a methodology that would permit the effective blockage of the Anopheles gambiae midgut wall penetration by Plasmodium parasites requires a detailed understanding of both the physiology of the mosquito's digestion, and of the interactions between the parasite and its host. We have transformed Drosophila melanogaster with several constructs that allow the study of the promoter region of two of the major late trypsin genes of A. gambiae. Using several deletions, we have identified, for both genes, small genomic segments that are sufficient to confer tissue specificity to the promoter in a species that is far away in evolution from the mosquito. This will allow further studies that will enable both the understanding of the blood meal digestion, and may potentially be useful for the design of anti-plasmodial constructs at a later stage.

Animals↗
PubMed1996

[Imaging (resolution and quantification) of corneal findings with ultrasound biomicroscopy].

Important information on the cornea can be obtained by ultrasound biomicroscopy. Intrastromal corneal scars, internal corneal adaptation after penetrating injuries or keratoplasties, corneal dystrophies and other lesions can be demonstrated. The acoustical examination is in competition with optical methods. It has advantages in opaque optical media and in rarely visible regions as well. The cornea is characterized acoustically by three highly reflective layers (epithelial surface, Bowman's membrane, Descemet's membrane) and two zones that are either not very reflective or are only in the middle range (the thin corneal epithelium without internal differentiation and the stroma) in which pathological structures can be seen.

Cornea↗
PubMed1995

[Significance of genotypes in chronic hepatitis C virus infection and hepatitis C virus induced liver cirrhosis in Germany].

INTRODUCTION AND OBJECTIVE: Hepatitis C virus (HCV) infection is characterized by a high chronicity rate. Several HCV genotypes have been described. As their distribution pattern in Germany had been unknown it was the aim of this study to determine it in a sizeable group of patients and to find out whether the genotypes differ in the severity of the disease caused by them. PATIENTS AND METHODS: 115 consecutive patients were studied prospectively, 62 (40 men, 22 women) with chronic HCV infection (group 1) and 53 (36 men, 17 women) with liver cirrhosis caused by HCV (group 2). The genotypes were determined by line probe assay. RESULTS: The mean age of the patients in group 1 was significantly lower than that in group 2 (40.4 +/- 13.7 vs 57.1 +/- 12.1 years; P < 0.0001). In group 1, genotype 1b was most frequent (53%; 1a: 21%, 3a: 21%, 2b: 3%, 2a: 2%). Genotype 1b also predominated in group 2 (78%; 1a: 17%, 2a: 4%, 3a: 2%). The differences in frequency between the two groups were significant regarding genotypes 1b (P = 0.01) and 3a (P = 0.005). Genotype 3a was found only in the younger patients. Mean age of patients with genotype 3a and chronic hepatitis C was significantly lower than that of the other patients in this group (34.2 +/- 4.6 vs 42.0 +/- 14.8 years; P < 0.002). CONCLUSIONS: The results show that in Germany genotype 1b predominates and seems to be associated more often with the advanced stages of liver disease. The fact that genotype 3a occurs exclusively in younger patients points to a change in genotype spectrum: infection with this genotype may take a less aggressive course since fewer cases of liver cirrhosis have been observed.

Adult↗
PubMed1995

Constitutive and blood meal-induced trypsin genes in Anopheles gambiae.

Trypsin genes in Anopheles gambiae are arranged as a tightly clustered gene family consisting of seven related coding sequences, devoid of introns. The two blood meal-inducible members of this family, Antryp1 and Antryp2, were shown to play a crucial role in the breakdown of the blood meal constituents. The role of Antryp3,4,5,6, and Antryp7 in the process of blood meal digestion remains to be elucidated. We have examined the localization and the expression patterns of these trypsins as well as the functional interactions in blood meal digestion between trypsins and other gut-specific proteases. Northern blot and RT-PCR analysis indicated that the genes Antryp3,4,5,6, and Antryp7 are all constitutively expressed in unfed female mosquitoes. Soon after blood feeding the mRNA of these trypsin genes became undetectable and appeared again at the end of the gonotrophic cycle. The blood meal-inducible trypsin Antryp1 was also constitutively expressed at low level in the gut of adult female mosquitoes. This trypsin was the only member of this gene family to be expressed in the gut of male and female pupae. By using antisera that specifically recognized recombinant Antryp4 we were able to show that the corresponding protein in Anopheles is synthesized and stored in the gut epithelium of unfed females as zymogen. Secretion and activation of this trypsin was shown to occur in the midgut lumen immediately after fluid ingestion and independently of the protein content of the meal. Recombinant trypsins expressed in Escherichia coli, with the exception of Antryp5 and Antryp6, were able to activate in vitro recombinant A. gambiae chymotrypsinogen, thus suggesting that blood meal ingestion is able to trigger a cascade of events leading to the activation of several proteases.

Amino Acid Sequence↗
PubMed1995

[Vitreous involvement in cytomegalovirus retinitis].

In our outpatient department we often see patients with vitreous inflammation. Recent reports emphasize that vitreous inflammation is very rare, so we looked for patients with cytomegalovirus (CMV) retinitis and vitreous inflammation. We investigated 359 HIV-positive patients for at least 1 year; all patients reached the stage of AIDS disease. We included patients without any retinal signs of CMV retinitis at the beginning or CMV recurrence during the study. A slit-lamp investigation, binocular funduscopy and b-picture ultrasound were done at regular intervals. The results show an increase in vitreous inflammation with the frequency of CMV retinitis recurrences. Patients very often develop retinal detachment. Vitreous inflammation is a critical factor when examining CMV retinitis. In the future a larger series of patients should be examined.

AIDS-Related Opportunistic Infections↗
PubMed1994

Characterization of antigenic determinants in the core antigen of the hepatitis C virus.

Antibodies to the hepatitis C virus (HCV) core protein are present in the majority of patients with chronic HCV infection. To characterize the corresponding determinants, synthetic peptides and various deletion clones of the core gene expressed in Escherichia coli were used to test human anti-core positive sera or rabbit anti-peptide antibodies in enzyme-linked immunosorbent assays, immunoblots, and competition assays. Two distinct linear antigenic determinants which are located within aa 1 to 20 and between aa 30 and 47 were found. Further studies using reactive serum after preabsorption of antibodies with N- and C-terminal-deleted HCV core proteins or with peptides directed to the linear epitopes revealed an additional determinant that requires for presentation the participation of the N-terminal 69 amino acids. It is postulated that the HCV core protein forms a three-dimensional structure exposing two linear epitopes and, in addition, presents a conformational determinant within the N-terminal 69 amino acids. The remaining core amino acid sequence spanning from position 69 to 191 does not seem to expose further determinants to induce additional anti-core antibodies.

Animals↗
PubMed1994

B-lymphocytes are predominantly involved in viral propagation of hepatitis C virus (HCV).

Recent reports have shown that HCV infection is not only restricted to hepatocytes. Like hepatitis B virus (HBV), which also was thought to be strictly hepatotropic in early molecular and cellular investigations, infection of lymphoid cells by HCV in vivo has been demonstrated. We showed that total peripheral blood leukocytes of chronically HCV-infected patients are infected by detection of plus- and minus-stranded HCV RNA using strand-specific oligonucleotide primers in the RT-PCR. These cells also represent extrahepatic sites for the viral replication, as demonstrated by incorporation of [3H]-uridine into nascent RNA after stimulation of the cells with a mitogen. Furthermore, total PBML from an uninfected person could be infected in vitro using an HCV-positive serum. It could be shown that replication of HCV RNA takes place in these cells. Examination of different subsets of PBML showed predominant infection of B-lymphocytes during HCV disease. Additionally, infection of T-lymphocytes was detected in about 50% of all chronically HCV-infected patients.

B-Lymphocytes↗
PubMed1994

Hepatitis C virus, alcoholic cirrhosis, and hepatocellular carcinoma.

We undertook a retrospective study to determine the prevalence of hepatitis C virus (HCV) and hepatitis B virus (HBV) infection in 81 Caucasian patients with confirmed hepatocellular carcinoma (HCC). Besides HBV and HCV serological markers, HCV RNA and HBV DNA were detected in serum and liver tissue by polymerase chain reaction. Overall, HCV RNA was found in 20 cases (25%), HBV DNA in 21 patients (26%), and coinfection in 3 patients (3%). HCV RNA in liver tissue was not found without virus in serum, whereas HBV DNA was found in the liver tissue of one patient without viremia. In an additional analysis, 32 patients with HCC and alcoholic cirrhosis (HCC-AC) were compared to 35 cases with AC without HCC and 35 cases with alcoholic hepatitis. The prevalence of HCV RNA in HCC-AC (19%) was significantly higher than in the other groups (AC, 3%; alcoholic hepatitis, 0%). HBV DNA was present in 19% of HCC-AC as compared to 3% of AC and 0% of alcoholic hepatitis. We conclude that the form of HCC in 50% of the patients in a Western European country is related to chronic viral hepatitis. Our data obtained from a group of patients having alcoholic liver disease with or without HCC suggest that the prevalence of HCV RNA or HBV DNA in these populations increases with the severity of hepatic injury.

Adult↗
PubMed1993

Thrombospondin related anonymous protein (TRAP) of Plasmodium falciparum binds specifically to sulfated glycoconjugates and to HepG2 hepatoma cells suggesting a role for this molecule in sporozoite invasion of hepatocytes.

Thrombospondin related anonymous protein (TRAP) of Plasmodium falciparum contains an amino acid motif based around the sequence WSPCSVTCG which is also found in region II of the circumsporozoite (CS) proteins of different species of Plasmodium. This amino acid motif confers on the CS protein the ability to bind specifically to sulfated glycoconjugates and to hepatocytes. This suggests that the interaction of CS protein with sulfated glycoconjugates on the surface of the hepatocytes may represent the first molecular event of sporozoite invasion of liver cells. Experimental evidence indicates that TRAP is localized both on the micronemes and on the surface of P. falciparum sporozoites implying that TRAP with its putative sulfated glycoconjugate binding motif may also be involved in recognition and/or entry of hepatocytes by the sporozoite. We show here that different TRAP constructs expressed in Escherichia coli bind to sulfogalactosyl-cerebrosides (sulfatides) and to the surface of HepG2 cells. These interactions are dependent on the presence of the conserved amino acid motif WSPCSVTCG within the sequences of the constructs and are completely inhibited by several sulfated glycoconjugates as well as by suramin, a polysulfonated drug with anti-protozoan activity. Moreover, sporozoite invasion of HepG2 cells is inhibited by antisera raised against these different TRAP constructs and by the presence of low concentrations of suramin. We concluded that TRAP may be one of the parasite encoded molecules in the host-parasite interaction that results in sporozoite invasion of hepatocytes.

Amino Acid Sequence↗
PubMed1993

Members of a trypsin gene family in Anopheles gambiae are induced in the gut by blood meal.

Serine proteases are among the enzymes that play a crucial role during the digestion of the blood meal in the gut of mosquitoes. The identification of the corresponding genes would have important implications for the control of mosquitoes and mosquito-borne diseases. Analysis of the genomic organization of these genes may lead to the isolation of a gut-specific, inducible promoter for the expression of anti-parasitic agents in transgenic mosquitoes. Moreover, specific inhibitors could be designed on the basis of the structural properties of the enzymes. We report here on the identification of a trypsin gene family in Anopheles gambiae, the mosquito vector of malaria in Africa. Mosquito trypsin-related sequences were amplified by PCR using as template cDNA derived from RNA of blood fed mosquitoes. Cloning of the PCR product revealed two distinct sequences. Corresponding full-length cDNA clones were obtained and sequenced. Antryp1 and Antryp2 code for proteins of 274 and 277 amino acids respectively, showing 75% homology at the amino acid level. The deduced amino acid sequences clearly identify them as trypsins. Five additional trypsin sequences were found in overlapping genomic clones. The genes identified are tightly clustered within 11 kb and sequencing indicates that no introns are present. Northern and PCR analysis indicated that the transcription of both Antryp1 and Antryp2 is induced by blood feeding. Moreover, the Antryp1 protein was detected among the proteins of a midgut lysate of blood fed mosquitoes using antisera against recombinant Antryp1. In addition, the recombinant polypeptides derived from Antryp1 and Antryp2 expressed in Escherichia coli showed a strong proteolytic activity against different sets of blood proteins. We conclude that the products of Antryp1 and Antryp2 play an important role in the breakdown of the proteins during the digestion of the blood meal in the mosquito gut.

Amino Acid Sequence↗
PubMed1993

Genetic variability of German hepatitis C virus isolates.

Heterogeneity of hepatitis C viral (HCV) genomes of several isolates from different countries has been reported, but there is little information on HCV isolates for the Federal Republic of Germany. Therefore, the nucleotide (nt) and deduced amino acid (aa) sequences of interesting parts of the viral genome derived from different human isolates in Germany were compared with each other and with the nt and predicted aa sequences of recently published isolates. HCV sequences were obtained by reverse transcription of viral RNA extracted from serum followed by polymerase chain reaction (PCR) amplification. Within the 5' nontranslated region we found only 3 single nucleotide exchanges among 2 of our isolates, and in comparison to sequences of Japanese isolates 2 to 3 exchanges, and to U.S. isolates 1 to 5 exchanges (homologies 98% to > 99%). Determination of a 249-bp core sequence from two German isolates exhibited 3% sequence divergence. The sequence of the core region (nt 342-911) showed a homology of about 88-91% on nt level and 96-97% on aa level as compared to U.S. isolates and other German isolates, and a homology of 95-96% (nt) and 96-98% (aa), respectively, to Japanese isolates. Less homologies were noticed for the E1 and E2/NS1 genes, especially in the N-terminal E2/NS1 hypervariable domain. Our isolates HD1 and HD2 showed nt sequence homologies of about 72-81% and aa homologies of 76-88% to U.S., German, and French isolates, and 89-91% (nt) and 88-96% (aa), respectively, to Japanese isolates. These results indicate that various German isolates are more closely related to Japanese isolates and differ from other European isolates as reported so far. Because of a nucleotide sequence heterogeneity of up to 10% among the tested isolates, we conclude that more than one closely related but distinct viral genotype of HCV exists in Germany. Furthermore, heterogeneous sequences of HCV can be detected in a single patient suggesting multiple infection with different genomic variants or, alternatively, a genetic drift forced by mutational events as a consequence of host immune selection.

Amino Acid Sequence↗
PubMed1993

A method for collecting large quantities of Cryptosporidium parasites.

The intestinal mucoso may be regarded as a potential and abundant source of Cryptosporidium parvurn parasites from which all developmental stages might be collected. If intracellular stages could be recovered from the brush border, many of the limitations concerned with the use of oocysts and in vitro cultures may be overcome. Hans-Michael Muller, Lorella Ranucci, Edoordo Pozio and Andrea Crisonti discuss here how this can be done.

Journal Article↗