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Biomedical subjects

J Rath

Publications and source records attributed to J Rath.

At least 19 recordsLinked to original sources
PubMed2000

Comparative analysis of denaturing gradient gel electrophoresis and temporal temperature gradient gel electrophoresis in separating Escherichia coli uidA amplicons differing in single base substitutions.

A set of Escherichia coli freshwater isolates was chosen to compare the effectiveness of denaturing gradient gel electrophoresis (DGGE) vs temporal temperature gradient gel electrophoresis (TTGE) for separating homologous amplicons from the respective uidA region differing in one to seven single base substitutions. Both methods revealed congruent results but DGGE showed a five to eight times higher spatial separation of the uidA amplicons as compared with TTGE, although the experiments were performed at comparable denaturing gradients. In contrast to TTGE, DGGE displayed clear and focused bands. The results strongly indicated a significantly higher discrimination efficiency of the spatial chemical denaturing gradient as compared with the temporal temperature denaturing gradient for separating the uidA amplicons. Denaturing gradient gel electrophoresis proved to be highly efficient in the differentiation of E. coli uidA sequence types.

Base Sequence↗
PubMed2000

Simultaneous detection and differentiation of Escherichia coli populations from environmental freshwaters by means of sequence variations in a fragment of the beta-D-glucuronidase gene.

A PCR-based denaturing-gradient gel electrophoresis (DGGE) approach was applied to a partial sequence of the beta-D-glucuronidase gene (uidA) for specific detection and differentiation of Escherichia coli populations according to their uidA sequence variations. Detection of sequence variations by PCR-DGGE and by PCR with direct sequencing correlated perfectly. Screening of 50 E. coli freshwater isolates and reference strains revealed 11 sequence types, showing nine polymorphic sites and an average number of pairwise differences between alleles of the uidA gene fragments (screened fragment length, 126 bp) of 2.3%. Among the analyzed strains a range of dominating to more rarely and/or uniquely observed E. coli sequence types was revealed. PCR-DGGE applied to fecally polluted river water samples simultaneously detected E. coli and generated a fingerprint of the mixed populations by separating the polymorphic uidA amplicons. No significant differences between non-cultivation-based and cultivation-based profiles were observed, suggesting that at least some members of all occurring sequence types could be cultivated. As E. coli is frequently used as a fecal indicator, this work is considered an important step towards a new, practical tool for the differentiation and tracing of fecal pollution in all kinds of waters.

Electrophoresis, Polyacrylamide Gel↗
PubMed1999

[Ciguatera poisoning. Growing differential diagnostic significance in the age of foreign tourism].

BACKGROUND: In the tropic sea there are carnivore fishes, e.g. the "peak bass", that incorporate toxin producing seaweed and can cause the ciguatera intoxication. Due to the frequent tourism to tropic regions even more cases of ciguatera intoxication can be seen in Europe. The late phase of ciguatera intoxication has hardly been recognized due to its different unspecific symptoms. In some cases ciguatera intoxication can even grow a vital threatening. CASE DESCRIPTION: Four patients from a travel group addressed us 4 and 14 days after breaking off their holidays in the Dominican republic. They presented complex neurological symptoms including paraesthesia, nervousness, inverse temperature perception, muscle cramps, headache and dizziness. The physical and apparative investigation of the patients, whose age ranked between 22 and 31 years, was totally unobtrusive. Essential for the diagnosis of ciguatera intoxication was the clue to the symptom causing dinner at their holiday location existing of "peak bass and lemon sauce". First symptoms in all members of the travel group were diarrhea, sickness and sweating. In this late phase only a symptomatic therapy could be offered. CONCLUSION: The here described cases show the importance of a comprehensive information for tropic travellers as for physicians accounted to in the acute phase of ciguatera intoxication, because recognized early enough (within the first 24 hours) the total symptomatology of ciguatera intoxication can be prevented effectively by intravenous infusions of mannitol.

Adult↗
PubMed1999

Helicobacter pylori detection in human biopsies: a competitive PCR assay with internal control reveals false results.

A polymerase chain reaction assay (PCR) for the diagnosis of Helicobacter pylori in human gastric biopsies was developed. To prevent false-negative results while performing PCR on human tissues, an internal control is necessary. Primer set ACT1-ACT2 which specifically amplifies a 542-bp fragment of the 16S rRNA gene of H. pylori was used. dUTP and hot-start were used to prevent false-positives from carryover of previous products and avoid non-specific extension products. A competitive internal control DNA fragment was constructed to detect the presence of inhibitors. Biopsies from 101 unselected patients with gastric symptoms were tested. PCR results were compared with results from microscopy of histological sections and conventional culturing for H. pylori. Forty-two percent of the biopsies were found to contain compounds inhibiting the PCR. The addition of the internal control assures the performance of the PCR assay and is an important quality control parameter.

Adolescent↗
PubMed1998

[Duplex ultrasound risk stratification of percutaneous puncture of the brachial artery for diagnostic and interventional coronary angiography].

Diagnostic and interventional heart catheterization in peripheral vascular disease often requires due to iliacal disease additional methods of arterial approach besides the Judkin's technique. The percutaneous catheterization of the brachial artery finds widespread use. A major complication linked with this method is an increased rate of thrombotic occlusions at the puncture site. Thus, we investigated in a prospective set-up the ability of duplex ultrasound to identify predictive risk factors for vascular complications. Over a period of 20 months, 8000 patients referred to heart catheterization were studied. Routine catheterization via the femoral route was contraindicated in 34 out of 8000 mostly due to severe peripheral vascular disease with multiple vascular risk factors (diabetes, hypertension, and smoking). 53 patients who had a comparable low risk-profile served as the control group. The brachial artery was examined by ultrasound duplex for vessel anatomy and diameter at the puncture site before coronary angiography. Both groups (patient and control group) showed in 15% a variable anatomy with a premature division of the brachial artery in 6% proximal of the elbow and in 9% already distal to the axillary artery. Because of reduced diameters of these variable vessels no procedure was carried out at these arms. In all cases the opposite arm was successfully used instead, because the variants were always located only at one arm. The diameter of the brachial artery measured in average 5.0 +/- 0.8 mm and 4.8 +/- 0.7 mm in patients and controls, respectively. Women had a significantly smaller vessel diameter than men, measuring a difference of 0.4 and 0.6 mm, respectively (p < 0.05). For coronary angiography 6F and 7F arterial sheats were used equally, and in 32% of all cases a coronary intervention was performed. 31 (91%) procedures were carried out without complications; there was a false aneurysm in 1 patient (3%) and an occlusion of the brachial artery at the puncture site in 2 patients (6%). The occluded vessels of two diabetic women had a reduced diameter at the level of 10% of the standard distribution and an unfavorable ratio of sheat-to-vessel-diameter which lead initially to an obstruction of nearly 50% of the vessel lumen during catheterization. Screening of the brachial artery by ultrasound duplex before a percutaneous catheterization for coronary angiography and intervention showed reproducibly the variable anatomy and differences in vessel diameter, which can be risk factors for thrombotic occlusion. Important details for the location of the puncture site and the possible size of the arterial sheat can be obtained, so that coronary interventions with 7F catheter systems are still practicable. This technique is a simple and efficient method to estimate the relative risk of arterial occlusion prior to percutaneous puncture of the brachial artery, especially in a group of patients with severe atherosclerosis and elevated vascular risk-factors.

Adult↗
PubMed1998

[Relevance and methods for determining coronary flow reserve].

The assessment of coronary flow reserve, defined as the ratio of hyperemic to resting coronary blood flow, allows a more functional analysis of the coronary vasculature in addition to coronary angiography. Three different kinds of cardiac catherization procedures for measurement of coronary flow reserve will be reviewed with respect to reliability, feasibility and clinical significance in the diagnosis and treatment of diseases of coronary conductance and resistive vessels: first, from the techniques utilizing selective catherization of coronary sinus, the thermodilution and the oxymetry have to be considered qualitatively rather than quantitatively because of a large variance and an underestimation of hyperemic blood flow responses. The gas chromatographic argon method provides a more quantitative rationale for the selective measurement of resting and hyperemic coronary flow, and thus to more exact differentiation between a reduced hyperemic vs an increased resting flow as a major cause of a reduced flow reserve. Furthermore, because of a reliable reproducibility this approach allows to proceed follow up studies to assess impact of therapeutic interventions on coronary flow reserve in individual patients. Second, angiographic methods utilize either densitometry or time-to-arrival measurements of defined boluses of contrast medium. The utility of the TIMI-frame count and of densitometric algorithms will be discussed. These methods offer the advantage of being rather easy to handle and to be performed within routine coronary angiography. However, they can be applied to a only rather small group of patients because of methodological limitations in patients with multivessel disease, with disturbed left ventricular function and with irregular heart rate. Third, this group comprises methods in which devices have to be advanced into coronary circulation such as pressure or doppler guide wires, which allows selective assessment of regional coronary flow and reserve. Currently evaluated approaches to assess significance of coronary stenosis will be discussed. In conclusion, currently different methods for the assessment of coronary flow reserve are available in cardiac catherization laboratories and each of these methods provides specific advantages and disadvantages, which have to be considered to select the appropriate approach for the diagnosis of functional disturbances of the coronary conductance and resistance vessels. The obtained functional data on coronary circulation should always be interpreted only in context with myocardial function and clinical symptoms of the individual patient.

Cardiac Catheterization↗
PubMed1998

An analysis of seven different methods to diagnose Helicobacter pylori infections.

BACKGROUND: It has been debated which diagnostic test should be preferred for the diagnosis of Helicobacter pylori in patients with gastroduodenal diseases. METHODS: The H. pylori infection was diagnosed prospectively in 97 untreated patients. H. pylori was diagnosed by means of tests based on five different principles: 1) culture, 2) microscopy (HLO), 3) urease activity (urea breath test (UBT) and urease test on biopsy specimens (CLO test)), 4) DNA detection (polymerase chain reaction (PCR)), and 5) IgG antibody detection (enzyme-linked immunosorbent assay (EIA) and Western blotting (WB)). RESULTS: This study showed that two positive tests out of five tests, based on different principles, were most reliable for predicting the H. pylori infection. Most tests had specificities and predictive values for a negative result greater than 90%. The most important difference between the tests was the sensitivity and the predictive value for a positive result (PPV). WB, HLO, UBT, and PCR had sensitivities and PPV greater than 75%. CONCLUSIONS: The non-invasive tests UBT and WB are reliable, both alone and in combination, and they are recommended for the pre-endoscopic diagnosis of H. pylori. WB is recommended as a confirmative test for antibody detection by EIA. When patients have an upper endoscopy, we recommend taking biopsy specimens for culture and histology because of the additional information obtained about susceptibility, virulence determinants, and morphology, including the degree of inflammation.

Adult↗
PubMed1998

Across the border: immigrants' economic opportunities, social capital and informal business activities.

"In this article, we [explore] the relationship between informal economic activities and recent immigrants in the Netherlands.... We will give an overview of important trends on both the demand and the supply side of entrepreneurial activities in the informal economy. We argue that the potential for informal economic activities by immigrants in large Dutch cities has been growing since the early 1980s. After having outlined this analytical framework, we examine some recent evidence on informal economic activities by immigrants in the Netherlands, especially in the bakeries sector, before concluding the discussion."

Demography↗
PubMed1997

[Formation, therapy and prevention of false aneurysm of the femoral artery following diagnostic and interventional heart catheterization].

OBJECTIVE: As pseudoaneurysm of the femoral artery after catheter introduction is a frequent complication, its causes and therapeutic options were investigated in a large patient collective. PATIENTS AND METHODS: In a prospective study with colour-Doppler duplex sonography of 6928 patients after diagnostic and of 3764 after interventional cardiac catheterisation, pseudoaneurysms were diagnosed in 80 patients (0.75%), 46 after diagnostic (0.66%) and 34 after interventional (0.9%) catheterisation. RESULTS: The incidence was higher in women than men (1.33% vs 0.58%; P < 0.05). Anticoagulation after sheath removal was the leading risk factor (n = 55, 68.8%), especially after interventional coronary intervention 85.3 vs 56.5%, P < 0.05). Local compression under duplex sonography monitoring was undertaken in 69 patients (86.3%), achieving aneurysmal obliteration in 53 (76.8%). Spontaneous thrombosis occurred in 15 of the remaining 27 patients, and surgical closure became necessary in 12. CONCLUSIONS: These data indicate a risk profile for the occurrence of pseudoaneurysm after cardiac catheterisation which can be dealt with by preventive measures. Local compression under duplex sonographic monitoring was the treatment of choice with a high success rate and low incidence of complications.

Aged↗
PubMed1997

[Incidence and therapy of peripheral arterial vascular complications after heart catheter examinations].

We analyzed the incidence and management of major vascular complications at the arterial puncture site following diagnostic or interventional cardiac catheterization. 27387 cardiac catheterization procedures were performed for diagnostic (n = 19581) or interventional (n = 7806) purposes at our institution during a 7-year study period. A total number of 114 major vascular complications (0.42%) were identified. In 36 (0.13%) patients an arterial occlusion at the puncture site was detected, 34 patients (0.12%) had severe hematoma (blood transfusion or surgical repair necessary), 32 patients (0.12%) developed false aneurysms, 9 patients (0.03%) with av-fistulas and 3 patients (0.01%) had other complications. The following factors were predictive for a significant increase in the incidence of major vascular complications: Female gender, interventional catheterization using larger introducer sheaths and necessitating effective perioperative doses of heparine, and peripheral vascular disease. Operative repair was necessary in 62 patients (54%), 34 patients (30%) were treated conservatively. In 18 patients (17%) acute vascular occlusion could be managed by percutaneous transluminal balloon dilatation and intravascular thrombolysis of the obstruction, in 3 patients additional stent-implantation was necessary in the presence of a large occlusive dissection. Overall the rate of clinically significant major vascular complications is low. In the future a greater number of vascular complications at the entry site for cardiac catheterization will be treated with nonoperative methods (e.g. manual compression of pseudoaneurysms or catheter-based techniques for recanalization of acutely occluded vessels.

Adult↗
PubMed1995

Skin atrophy induced by initial continuous topical application of clobetasol followed by intermittent application.

BACKGROUND: The most frequent side effect of a long-term topical corticosteroid therapy is skin atrophy. To avoid or to reduce atrophy often an initial continuous application is followed by an intermittent maintenance therapy. OBJECTIVE: In this study we measured the skin thickness before and after the two-phase application schedule with the superpotent topical steroid clobetasol propionate (CP). For 16 days CP samples were applied twice daily on the test areas of 12 volunteers (phase 1). Then CP was applied to the same skin areas in accordance with the following timing: every 5th day, every 7th day, every 10th day, every 14th day (phase 2). Phase 2 lasted for 45 days. During the entire period of the study the skin thickness was measured regularly by the skin compression and thickness method as described previously. RESULTS: It could be seen that in phase 1 the skin became about 15% thinner. In phase 2 the steroid-induced skin thinning was approximately the same when CP was applied every 5th or 7th day. The skin thickness reached a more or less normal level when CP was applied every 10th day. After the 14th day a completely normal level was found. By measuring the skin thickness every day it was further shown that the skin thinning process lasted for 3 days when CP was applied once only. CONCLUSION: These results demonstrate that skin thinning must be expected by an intermittent maintenance therapy applied at relatively short intervals. The longer the intervals, the weaker the skin thinning. Moreover, these investigations showed that the skin thinning effect after a single CP application persists for nearly 3 days.

Administration, Topical↗
PubMed1995

The alpha-D-mannan core of a complex cell-wall heteroglycan of Trichoderma reesei is responsible for beta-glucosidase activation.

A heteroglycan responsible for the binding of the enzyme beta-1,4-D-glucosidase (EC 3.2.1.21) to fungal cell walls was isolated from cell walls of the filamentous fungus Trichoderma reesei. The heteroglycan, composed of mannose, galactose, glucose, and glucuronic acid, also activated beta-1,4-D-glucosidase, beta-1,4-D-xylosidase and N-acetyl-beta-1,4-D-glucosaminidase activity in vitro. The structural backbone of this heteroglycan was prepared by acid hydrolysis and gel filtration. The molecular structure of the core of the heteroglycan was determined by NMR studies as a linear alpha-1,6-D-mannan. The mannan core obtained by acid degradation stimulated the beta-glucosidase activity by 90%. Several glycosidases from Aspergillus niger were also activated by the T. reesei heteroglycan. The beta-glucosidase of Trichoderma was activated by mannan from Saccharomyces cerevisiae to a comparable extent.

Acetylglucosaminidase↗