Biomedical subjects

H M Müller

Publications and source records attributed to H M Müller.

At least 37 records · Page 2Linked to original sources

PubMed2000

Noninvasive measurement of pulmonary vascular resistances by assessment of cardiac output and pulmonary transit time.

RATIONALE AND OBJECTIVES: Pulmonary vascular resistance is of special interest in many diseases. Usually it is determined invasively by catheterization, but cardiac output and pulmonary transit time can be ascertained by several noninvasive methods. METHODS: Fourteen heart recipients (age 34-71 years) were examined by electron-beam CT of the heart. Cine and flow studies were performed using a total of 60 mL of contrast and a breath-hold of 20 seconds. RESULTS: A mathematical model for calculating pulmonary vascular resistances from noninvasively measured cardiac outputs and pulmonary transit times was developed. Right-sided heart catheterization served as the reference method. CONCLUSIONS: The formula created seems to allow a clinically valid estimate of pulmonary vascular resistance from noninvasively acquired data.

Algorithms↗

PubMed1999

Genomic structure and ecdysone regulation of the prophenoloxidase 1 gene in the malaria vector Anopheles gambiae.

Prophenoloxidase, a melanin-synthesizing enzyme, is considered to be an important arthropod immune protein. In mosquitoes, prophenoloxidase has been shown to be involved in refractory mechanisms against malaria parasites. In our study we used Anopheles gambiae, the most important human malaria vector, to characterize the first arthropod prophenoloxidase gene at the genomic level. The complete nucleotide sequence, including the immediate 5' flanking sequence (-855 bp) of the prophenoloxidase 1 gene, was determined. The gene spans 10 kb and is composed of five exons and four introns coding for a 2.5-kb mRNA. In the 5' flanking sequence, we found several putative regulatory motifs, two of which were identified as ecdysteroid regulatory elements. Electrophoretic mobility gel-shift assays and supershift assays demonstrated that the Aedes aegypti ecdysone receptor/Ultraspiracle nuclear receptor complex, and, seemingly, the endogenous Anopheles gambiae nuclear receptor complex, was able to bind one of the ecdysteroid response elements. Furthermore, 20-hydroxyecdysone stimulation was shown to up-regulate the transcription of the prophenoloxidase 1 gene in an A. gambiae cell line.

Animals↗

PubMed1999

A hemocyte-like cell line established from the malaria vector Anopheles gambiae expresses six prophenoloxidase genes.

Cell lines from the malaria vector Anopheles gambiae have been established as a tool for the study of the mosquito innate immune system in vitro. Here, we describe the first continuous insect cell line that produces prophenoloxidase (PPO). This cell line (4a-3B) expresses constitutively six PPO genes, three of which are novel (PPO4, PPO5, and PPO6). The PPO genes show distinct temporal expression profiles in the intact mosquito, spanning stages from the embryo to the adult in an overlapping manner. Transient induction of larva-specific PPO genes in blood-fed adult females suggests that the developmental hormone 20-hydroxyecdysone may be involved in PPO gene regulation. Indeed, exposure of 4a-3B cells to 20-hydroxyecdysone in culture results in induction of those PPO genes that are mainly expressed in early developmental stages, and repression of PPO5, which is preferentially expressed at the adult stage. The cell line shows bacteria-induced immune transcripts that encode defensin and Gram-negative bacteria-binding protein, but no induction of PPO transcripts. This cell line most likely derives from a hemocyte lineage, and represents an appropriate in vitro model for the study of the humoral and cellular immune defenses of A. gambiae.

Amino Acid Sequence↗

PubMed1999

[Indications and contraindications of lacrimal duct balloon dilatation].

PURPOSE: The aim of the study was to determine the indications and contraindications for balloon dacryocystoplasty. MATERIAL AND METHODS: So far 85 patients with severe epiphora because of relative stenosis (n = 47) or occlusion (n = 38) of the nasolacrimal duct have undergone dilation. The success rates were evaluated during the acute phase and the follow-up period of 6-12 months. Treatment failures and recurrence of stenosis were analyzed and compared to the clinical and dacryocystographic indications prior to treatment. RESULTS: A recanalization success rate of 79% was achieved in patients with isolated postsaccal stenoses or short-distance occlusions of the nasolacrimal duct. Patients with additional presaccal and saccal stenoses, filling defects in the duct lumen, or long-distance occlusions had lower initial recanalization rates (66%). Main predictors for recurrent obstructions were active inflammation, filling defects due to calculi, extensive occlusion and post-traumatic lesions. In the absence of these factors 12-month patency rates of 80% were proved. CONCLUSION: Dacryocystoplasty procedures should preferably be performed in patients with circumscribed functional postsaccal stenosis. In these cases a success rate of about 80% is possible. Otherwise the value of the intervention is limited by high failure and recurrence rates.

Adult↗

PubMed1999

A survey of Fusarium toxins in cereal-based foods marketed in an area of southwest Germany.

A total of 237 commercially available samples of cereal-based foods including bread and related products, noodles, breakfast cereals, baby and infant foods, rice and other foods were randomly collected in southwest Germany during the first six months of 1998. The trichothecenes deoxynivalenol (DON), 3- and 15-acetyl-deoxynivalenol (3-,15-ADON), nivalenol (NIV), fusarenon-X (FUS-X), T-2 toxin (T-2) and HT-2 toxin (HT-2) were determined by gas chromatography/mass spectrometry following clean-up by a two stage solid-phase extraction. Detection limits ranged between 2 and 12 micrograms/kg. Based on all samples, the incidence of DON, HT-2, T-2, 3-ADON, 15-ADON, and NIV was at 71, 18, 4, 4, 4 and 2%, respectively; the average contents in positive samples were at 103, 16, 14, 17, 24 and 109 micrograms/kg, respectively. Fus-X was not detected in any sample. A lower (P < 0.05) DON content was found in baby and infant foods as well as in cookies and cakes compared to bread. Overall, based on the incidence and level of all six toxins, the degree of contamination was lowest in baby and infant foods. Foods produced from either white or whole grain flour did not differ (P > 0.05) with regard to the incidence and level of DON. In foods produced from cereals of organic production both the incidence and median content of DON was lower compared to conventional production. Zearalenone, alpha- and beta-zearalenol were determined by high performance liquid chromatography in 20 selected samples, mostly baby and infant foods. These toxins were not present in excess of the detection limit in any sample.

Bread↗

PubMed1999

The gastrointestinal system--an essential target organ of the athlete's health and physical performance.

An athlete's ability to reach maximum performance is a direct result of physical and muscular performance, muscular and systemic stress tolerance, control and regulation of immune function, and adaptation to physical stress. In this complex sense, the gastrointestinal (GI) tract is also part of the system that controls and regulates adaptation and regeneration of the athlete. A well-balanced GI immune system and an optimized immune competence may protect the athlete from harmful pathogens; it may also protect against dietary as well as inhaled antigens. However, under conditions of mechanical and biochemical stress, the integrity of the GI mucosal block, particularly the epithelial hood, can be damaged, leading to a pathological uptake of toxic or immunogenic substrates. This may occur in endurance athletes, since gut symptomatology, nausea, vomiting, pain, bloating, diarrhea, cramping, and bleeding can be observed in up to half of all participants in endurance events. In addition, composition of stool and fecal microflora in endurance athletes has shown that there may be a specific need for nutritional support for mucosal immunity in highly trained but chronically stressed athletes. Proper diet during training and competition is a significant factor in guarding against GI symptoms and exercise-induced gastrointestinal side effects that may compromise immune competence and physical performance. The present review presents some important suggestions on the possible role of the GI tract in human performance and stress tolerance, and offers new insights about the influence of food quality on the immune system of the gut.

Digestive System↗

PubMed1999

How does Anopheles gambiae kill malaria parasites?

The malaria parasite's lifecycle in the mosquito vector Anopheles gambiae involves several translocations within and between tissues during which large parasite losses have been documented. Interestingly, during the critical transition stages of midgut invasion and relocation of sporozoites from the oocysts to the salivary glands the mosquito innate immune system is activated. These defense reactions could, at least partially, be responsible for the parasite killing in the mosquito. This important question is now being approached by the dissection of the mosquito innate immune system as well as genetic and genomic studies.

Animals↗

PubMed1999

Telemedicine based screening of infants at risk for retinopathy of prematurity.

Retinopathy of Prematurity (ROP) is a major risk for permanent visual loss in extreme prematures. In stage 3+ (zone I and II), defined as threshold disease, the risk for retinal detachment with subsequent blindness is about 50% without treatment, compared to only a few percent with laser photoablation. Visualisation and interpretation of the critical retinal changes requires a high degree of expertise. Therefore, screening by general ophthalmologists will not identify all cases at threshold necessary to prevent blindness in as many infants as possible. The development of a new digital wide-field camera system (RetCam 120) allows documentation of nearly the entire retina within minutes. Recently, sensitivity, specificity, positive predictive power and negative predictive power have been evaluated to be high. Data collection is also possible by trained staff of the neonatal care units. Data can be transferred electronically, even though it could be transferred through physical transport. Analyzing the data in a central reading center specialized in the treatment of ROP will allow optimal timing of treatment and thus salvage vision in more infants. In addition, unnecessary referrals that are not only expensive but put also stress on the very vulnerable prematures can be avoided. At present, efforts are made to realize a pilot project in Eastern Bavaria that will test the potentials of telemedicine based screening for ROP. In addition, the potential of the system will be evaluated in other neuroophthalmological diseases.

Germany↗

PubMed1998

Determination of eight trichothecenes by gas chromatography-mass spectrometry after sample clean-up by a two-stage solid-phase extraction.

A method is described for the determination of eight trichothecenes of type A and B in a variety of complex matrices including heavily moulded and pigmented cereals, whole cereal ears, cereal-based foods, mixed feeds and faeces from swine. Trichothecenes were determined as their trifluoroacetyl derivatives by gas chromatography with ion-trap mass spectrometry detection operating in chemical ionization mode. Isobutane was chosen as reactant gas and optimum parameters of measurement were determined. For sample preparation a clean-up procedure was developed using a combination of Florisil and cation-exchange cartridges for solid-phase extraction. Limits of detection and quantification as well as recoveries are described.

Animals↗

PubMed1998

Kinetic profiles of ochratoxin A and ochratoxin alpha during in vitro incubation in buffered forestomach and abomasal contents from cows.

Pure ochratoxin A (OA) was added to buffered rumen fluid collected from fistulated cows and incubated under anaerobic conditions. The kinetic pattern of the disappearance of OA and the appearance of ochratoxin alpha (Oalpha) was principally the same with four diets fed to donor animals and with three donor animals. The concentration of OA declined to a very low or non-detectable level with half-lives at 0.17-1.84 h; its rate of disappearance was first order throughout. The concentration of Oalpha increased to a constant level under all conditions examined. The average amounts of Oalpha formed relative to the disappearance of OA were not different (p > 0.05) and ranged between 94 +/- 8 and 98 +/- 8 %. The rate of disappearance of OA differed (p < 0.001) between diets and animals. It was accelerated by increasing the content of concentrate in the diet. Ochratoxin alpha was not metabolized when added in pure form to buffered rumen fluid and incubated under the same conditions as OA. Pure OA was also added to buffered fluids from the forestomach and abomasum of a slaughtered cow. It disappeared exponentially in a mixture of fluids from the rumen and reticulum and in fluid from the omasum, with the average amounts of Oalpha formed relative to OA disappearance being 107 and 109 %, respectively. Ochratoxin A also was not metabolized in fluid from the abomasum. These studies demonstrate that OA is hydrolysed in the rumen via first order kinetics, diet and animal affect the rate of hydrolysis, OA is quantitatively converted to Oalpha and Oalpha is not degraded.

Abomasum↗

PubMed1998

Mild chronic anemia following heart transplantation: a syndrome with prognostic relevance?

The clinical relevance of mild chronic anemia in patients after heart transplantation (HTX) has not yet been demonstrated. Forty-five outpatients who had undergone HTX 2-99 months prior to investigation and who had not received blood transfusions or erythropoietin (EPO) before data acquisition were observed over a period of 37 months. Anemia was found in 36 of the 45 patients and was normocytic, normochromic, and slightly anisocytotic (coefficient of variation = 16 +/- 2, normal 11.5-14.5). Anemic patients showed elevated EPO levels, whereas in nonanemic patients EPO levels were normal. Survival after HTX differed significantly in anemic and nonanemic patients (P < 0.02), with 100% survival in the nonanemic and 85% in the anemic group. Chronic anemia in patients after HTX shows a typical pattern. Even when mild, anemia in patients after HTX seems to be of prognostic value and thus might be an indicator of chronic disorders.

Adolescent↗

PubMed1998

[Correction of myopic astigmatism with the VISX 20/20 excimer laser. An overview of treatment outcome].

UNLABELLED: The advent of the excimer laser has brought about the potential for improved vision in many individuals with myopia and astigmatism. However, photoastigmatic refractive keratectomy (PARK) remains a matter of controversy. The purpose of our study was to determine the predictability of VISX 20/20 excimer laser photorefractive keratectomy in the treatment of myopic astigmatism. PATIENTS AND METHODS: Our study comprised 31 eyes of 22 patients with myopic astigmatism. All patients underwent treatment with a VISX 20/20 excimer laser and were followed up for 6 months. Complete 12-month follow-up data were available from 18 eyes. Park was performed in eyes with myopia between -1.5 and -10.0 D and with astigmatism between -0.5 and -5.5 D. Thus, the corresponding spherical equivalent ranged from -1.75 to -10.5 D. RESULTS: Six months postoperatively, 21/31 (62%) eyes were within +/- 1.0 D of the target refraction and 13/31 (42%) within +/- 0.5 D of the target refraction. In 13 of 15 eyes (87%) with myopia less than -6.0 D, an uncorrected visual acuity of at least 0.8 was noted. In eyes with myopia greater than -6.0 D, 9/16 (56%) showed an uncorrected visual acuity of at least 0.5. Six months after PARK, an increase of one line on the Snellen Visual Acuity Chart was observed in 8/31 (26%) and an increase of two lines was noted in eyes 3/31 (10%). One of 31 eyes (3%) showed an increase of three lines. A decrease in visual acuity of 1 line on the Snellen Visual Acuity Chart was found in 4/31 (13%), and in 3/31 eyes (10%) a decrease of 2-4 lines was noted. Overall, we observed a statistically significant reduction of astigmatism from 1.93 +/- 1.43 D to 0.93 +/- 0.63 D. Reduction of corneal astigmatism less than -1.25 D was not statistically significant. In eyes with astigmatism ranging from -1.25 to -2.5 D or greater than -2.75 D, a significant reduction of the mean astigmatism was noted. The postoperative regression of astigmatic correction was low. However, an axis shift of more than 15 degrees was found in 42%/35% of eyes by subjective refraction (miosis/cycloplegia) and in 33% in corneal topography. No central islands were noted. CONCLUSION: Photoastigmatic refractive keratectomy (PARK) constitutes a potential means of correcting myopic astigmatism. In eyes with astigmatism greater than -1.0 D a significant reduction of 60% of the mean astigmatism was noted. However, the considerable proportion of eyes with a postoperative axis shift greater than 15 degrees and a decrease in visual acuity of two or more lines indicates that further research is needed on excimer laser surgery to improve the reliability and safety.

Adult↗

PubMed1998

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

A total of 56, 56, 54, 51, and 55 oats samples used for feed production were collected randomly after the 1987, 1989, 1990, 1991 and 1992 crops, respectively, from farms located in an area of southwest Germany. Deoxynivalenol (DON), 3- and 15-acetyl-deoxynivalenol (3-, 15-ADON), nivalenol (NIV), fusarenon-X (FUS-X), T-2 toxin (T-2), HT-2 toxin (HT-2) and diacetoxyscirpenol (DAS) were determined by gas chromatography with mass selective detection (GC-MS), zearalenone (ZEA), alpha and beta-zearalenol (alpha-, beta-ZOL) by GC-MS or by HPLC. DON was the major toxin with incidences at 49-85% and mean levels in positive samples of 52-302 micrograms/kg. Incidences of ZEA, 3-ADON, NIV, HT-2, and T-2 were at 20-37, 0-30, 18-67, 0-29, and 27-61%, respectively, with mean levels in positive samples at 8-25, 5-63, 11-192, 205-296, and 20-244 micrograms/kg, respectively. alpha- and beta-ZOL and DAS were not detected in any sample. 15-ADON and FUS-X were assayed in samples from 1987, 1991 and 1992. 15-ADON was detected in 9, 4 and 0% of samples, with an average of 9 and 18 micrograms/kg, respectively; FUS-X was not detected. The incidence and levels of toxins varied from year to year. The correlation between the occurrence of toxins and precipitation is discussed.

Animals↗

PubMed1998

[Prediction of preeclampsia:new hypotheses, new approaches].

Preeclampsia is a multisystem disorder affecting 5.8% of primigravidas. It is a progressive disease with a very variable mode of presentation and rate of progression. Of all the features of the syndrome, hypertension and pregnancy-induced proteinuria are the classic clinical manifestations. This disease causes severe complications of the mother and the fetus. Neither are factors available for prediction, nor are there strategies for prevention and therapy of this disease. The accumulated evidence strongly suggests that failure or incomplete trophoblastic invasion (end of first, beginning of second trimester) of the spiral arteries, resulting in narrowed spiral arteries and subsequent endothelial damage, is responsible for the occurrence of this disease (third trimester). The reason for trophoblastic failure is not known. After clinical symptoms have occurred, only symptomatic therapeutic options are available. In this paper, we discuss potential ways to find specific and sensitive predictive parameters according to the current knowledge of the pathophysiology of this pregnancy-induced severe disorder.

Blood Pressure Determination↗

PubMed1997

Molecular immune responses of the mosquito Anopheles gambiae to bacteria and malaria parasites.

Immune responses of the malaria vector mosquito Anopheles gambiae were monitored systematically by the induced expression of five RNA markers after infection challenge. One newly isolated marker encodes a homologue of the moth Gram-negative bacteria-binding protein (GNBP), and another corresponds to a serine protease-like molecule. Additional previously described markers that respond to immune challenge encode the antimicrobial peptide defensin, a putative galactose lectin, and a putative serine protease. Specificity of the immune responses was indicated by differing temporal patterns of induction of specific markers in bacteria-challenged larvae and adults, and by variations in the effectiveness of different microorganisms and their components for marker induction in an immune-responsive cell line. The markers exhibit spatially distinct patterns of expression in the adult female mosquito. Two of them are highly expressed in different regions of the midgut, one in the anterior and the other in the posterior midgut. Marker induction indicates a significant role of the midgut in insect innate immunity. Immune responses to the penetration of the midgut epithelium by a malaria parasite occur both within the midgut itself and elsewhere in the body, suggesting an immune-related signaling process.

Acute-Phase Proteins↗

PubMed1997

Fusarium toxins in wheat harvested during six years in an area of southwest Germany.

A total of 84, 78, 80, 80, 78, and 45 wheat samples for feed use were collected randomly after the 1987, 1989, 1990, 1991, 1992, and 1993 crops, respectively, from farms in an area of southwest Germany. The sum of precipitation from May to September varied during years, with markedly higher precipitation in 1987, compared to 1989-1993. Deoxynivalenol, 3- and 15-acetyldeoxynivalenol, nivalenol, HT-2 toxin, T-2 toxin, diacetoxyscirpenol, and fusarenon-X were determined by gas chromatography, combined with mass selective detection (GC-MS), zearalenone, alpha- and beta-zearalenol by GC-MS or HPLC. Deoxynivalenol was the major toxin, with incidences of 68-95% and mean contents at 152-1,692 micrograms/kg. In contrast, incidences of zearalenone, 3-acetyldeoxynivalenol, nivalenol, HT-2 toxin, and T-2 toxin were at 11-80, 17-60, 25-64, 0-8, and 0-41%, respectively, with mean contents between 3 and 209 micrograms/kg. alpha-zearalenol and/or beta-zearalenol were detected in five samples at contents < or = 71 micrograms/kg; diacetoxyscirpenol was not detected in any sample. 15-acetyldeoxynivalenol and fusarenon-X were assayed in samples from 1987 and 1991-1993. 15-acetyldeoxynivalenol was detected in 3-15% of samples at mean contents of 5-84 micrograms/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 precipitation is discussed.

Animal Feed↗

PubMed1997

Clinical presentation of GB-C virus infection in drug abusers with chronic hepatitis C.

BACKGROUND/AIMS: Recently, the hepatitis GB-C virus (GBV-C) has been identified as another virus potentially causing chronic hepatitis. Although high rates of coinfection are emerging in drug addicts with chronic hepatitis C virus infection, no detailed data on clinical presentation are available. Therefore, co-infection was sought in hepatitis C virus patients to determine the impact of GB-C virus on clinical presentation. METHODS: GBV-C was determined by nested reverse transcriptase-polymerase chain reaction in serum of 70 HIV negative intravenous drug abusers with chronic hepatitis C. Biochemical, histological and virological parameters were compared between patients with or without GBV-C coinfection. RESULTS: Hepatitis C virus and GBV-C coinfection was found in 18 of 70 (25.7%) patients. Cases with coinfection were younger and had shorter duration of disease (31.4+/-6.2 vs. 35.3+/-7.3 (p=0.09) and 9.9+/-6.8 vs. 12.9+/-7.7 (p=0.17) years) than those without coinfection. Neither hepatitis C virus genotype distribution and HCV RNA levels nor serum liver function tests, titers of immunoglobulins or autoantibodies differed between the two groups. Histologically, chronic active hepatitis (16.7 vs. 46.4%, p=0.07), fibrosis (8.3% vs. 21.4%, p=0.3), and cirrhosis (0% vs. 8.2%, p=0.31) were less prevalent in coinfected patients. After interferon treatment, 5/6 coinfected and 11/19 patients with hepatitis C virus infection alone had cleared HCV RNA and 4/6 lost GBV-C RNA from serum. The two patients with GBV-C/HCV infection who persistently cleared hepatitis C virus but not GBV-C from serum had normal transaminases during follow-up despite persistence of GBV-C. CONCLUSIONS: Coinfection of chronic hepatitis C patients with GBV-C does not lead to a significant change in clinical presentation, severity of liver disease, hepatitis C viremia, or response to interferon treatment.

Adult↗

PubMed1997

Event-related potentials elicited by spoken relative clauses.

Sentence-length event-related potential (ERP) waveforms were obtained from 23 scalp sites as 24 subjects listened to normally spoken sentences of various syntactic structures. The critical materials consisted of 36 sentences each containing one of two types of relative clauses that differ in processing difficulty, namely Subject Object (SO) and Subject Subject (SS) relative clauses. Sentence-length ERPs showed several differences in the slow scalp potentials elicited by SO and SS sentences that were similar in their temporal dynamics to those elicited by the same stimuli in a word-by-word reading experiment, although the effects in the two modalities have non-identical distributions. Just as for written sentences, there was a large, fronto-central negativity beginning at the linguistically defined "gap" in the SO sentences; this effect was largest for listeners with above-median comprehension rates and is hypothesized to index changes in on-line processing demands during comprehension.

Adolescent↗