PubMed Health⌕ Search

Biomedical subjects

W Jansen

Publications and source records attributed to W Jansen.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Cardioversion in atrial fibrillation. Results and complications in 1,152 prospective patients. Study Group of the Working Society of Leading Cardiologic Hospital Physicians].

BACKGROUND: Pharmacological and direct-current cardioversion of atrial fibrillation are often performed interventions. Little is known about results and complications of cardioversion in daily practise. PATIENTS AND METHODS: Demographic, procedural and outcome data from patients with cardioversion of atrial fibrillation were collected in a prospective, multicenter registry of 61 hospitals. RESULTS: Between July 1994 and December 1994 1152 patients with a mean age of 64 +/- 11 years were registered on an intention-to-treat basis. 62% were male. The most prevalent underlying disorders were coronary artery disease (34.7%), valvular heart disease (18.1%), and cardiomyopathy (6.9%). 16.4% of patients had lone atrial fibrillation. New onset atrial fibrillation was reported in 21%, paroxysmal in 32% and chronic in 47% of patients. The mean duration of atrial fibrillation was 7 +/- 26 weeks (range 1 day to 7 years, median 5 days). In 3.8% of patients no cardioversion attempt was made and follow-up was not possible in another 5.5%. 19.2% of patients cardioverted spontaneously. Direct current cardioversion was attempted in 39.7% and pharmacological cardioversion in 31.8% of patients. Cardioversion was successful (sinus rhythm at discharge) in 96.4% of spontaneous cardioversion, in 73.1% of direct current cardioversion and in 84.4% of pharmacological cardioversion. Success of cardioversion was significantly related to duration of atrial fibrillation, NYHA functional class and left atrial diameter (p < 0.001). In 55 (4.8%) cases complications were reported of which 14 were fatal. Five cases of sudden death occurred, all of which were related to quinidine therapy for pharmacological cardioversion. Five cases of embolism were reported. Two were not associated with cardioversion attempts and 3 occurred within 24 hours after successful direct current cardioversion. Two of these patients were effectively anticoagulated at the time of cardioversion. A total of only 62% of patients with atrial fibrillation of more than 48 hours duration were anticoagulated for cardioversion with coumadine or i.v. heparin. CONCLUSIONS: The main risks of cardioversion are fatal proarrhythmic events in pharmacological attempts to restore sinus rhythm. The risk of embolism is despite low rates of effective anticoagulation low.

Aged↗
PubMed1995

Neurological observations after local irradiation and hyperthermia of rat lumbosacral spinal cord.

PURPOSE: Investigation of the effects of hyperthermia on the radiation response of rat lumbosacral spinal cord with respect to: (a) incidence of paralysis, (b) latency, (c) histopathology, and (d) tumor induction. METHODS AND MATERIALS: Rat lumbosacral spinal cord with the cauda equina was single-dose irradiated with 15 to 32 Gy of x-rays. Hyperthermia for 30 min at a spinal cord temperature of 41.1, 42.3, and 42.6 +/- 0.4 degrees C was applied 5 to 10 min after irradiation by means of a 434 MHz microwave applicator. Animals were observed for 21 months while recording myelopathy and development of tumors. RESULTS: The latent period for hind leg paralysis decreased with increasing radiation dose from 359 +/- 31 days (n = 9) after 20 Gy to 200 +/- 4 days (n = 5) after 32 Gy. Hyperthermia enhanced the radiation response of the lumbosacral spinal cord as evidenced by shortening of the latent period for paralysis and a decrease in the biological effective dose. After 20 Gy followed by 30 min 41.1 degrees C, latency was diminished to 214 +/- 16 days (n = 7, p < 0.001 vs. 20 Gy alone). The ED50 was 21.1 Gy, which was diminished to values between 16 and 17 Gy if radiation was followed by hyperthermia, giving a thermal enhancement ratio between 1.24 and 1.32. Histopathological examination of the spinal cord after combined treatment of x-rays and hyperthermia showed necrosis of nerve roots. Irradiation with 16, 20, 24, and 28 Gy (n = 77) alone led to tumor induction in 17 +/- 8% of the animals (pooled data). If followed by hyperthermia (n = 96), it was increased to 33 +/- 12% (p < 0.01). Most tumors induced by radiation and hyperthermia were sarcomas. CONCLUSION: First, the radiation response of rat lumbosacral spinal cord was enhanced by heat. Second, latency for paralysis was shortened in the lower dose range. Third, no difference in pathology between x-rays alone or in combination with hyperthermia. Fourth, hyperthermia did increase radiation carcinogenesis.

Animals↗
PubMed1994

[Congenitally corrected transposition of the great vessels in adulthood. The value of noninvasive study methods].

A 57-year-old man with a cough and increasing exertional dyspnoea for the past 6 weeks was found on examination to have a loud systolic murmur and cardiomegaly with pulmonary congestion. Echocardiography revealed congenitally corrected transposition of the great arteries (cTGA: atrioventricular and ventriculoarterial discordance): a morphologically right ventricle with a tricuspid valve on the left, a morphologically left ventricle with bicuspid a-v valve on the right, the aorta arising ventrally from the left-sided (morphologically right) ventricle. The tricuspid valve showed an Ebstein-like anomaly with obvious regurgitation. Transoesophageal and contrast echocardiography defined valvar anatomy, attachment of the great arteries and cardiac chambers to the venous and arterial circulations, as well as absence of a left to right shunt. Angiography revealed a coronary anatomy typical for cTGA. The exertional dyspnoea responded to diuretics and low doses of ACE inhibitor. Follow-up monitoring of the valvar regurgitation and appropriate endocarditis prophylaxis were recommended. As the haemodynamics in cTGA is normal, in the absence of additional anomalies, it is a congenital cardiac defect which can, though rarely, present first in adulthood. Life expectancy depends on the nature of any additional defects and the degree of commonly associated tricuspid valve regurgitation. As this case demonstrates, echocardiography can largely define the anomalies.

Captopril↗
PubMed1994

Capillary changes in angiokeratoma corporis diffusum Fabry.

We report on capillary changes on the Sulcus matricis unguis in a patient with an established angiokeratoma corporis diffusum Fabry. A fasciculated ramification of the capillary in 2-5 loops, which is not found in healthy individuals and that until now has solely been described in patients with vasculitis, was detected. The question now arises whether these are initial changes in the disease which later lead to manifested angiokeratomas. Further investigations will show if, and to what extent, these observations can contribute to further clarification of the developmental method of acroparaethesiae, which are part of the principal signs of Morbus Fabry.

Adult↗
PubMed1994

[Examination procedure in automated determination of far and near vision].

BACKGROUND: Although the measurement of visual acuity at distance is more important in ophthalmological practice, the visual acuity at near should be tested additionally. In a recently published paper we showed that with today's computer technology visual acuity at distance can be measured in standardized procedures according to DIN 58220. We describe here an additional, integrated setup, which allows the measurement of visual acuity also at near. METHODS: For testing visual acuity at near, the whole set of optotypes is presented on a transparent overlay mask in front of a computer monitor which is used as a program-controlled light source. A certain optotype is chosen by illuminating its background. The patient's responses are read via a small console by the computer. The test procedure follows the DIN requirements. RESULTS AND CONCLUSIONS: First reliability tests showed that the test arrangement is qualified for rapid and standardized determination of visual acuity at near and at distance under nearly natural viewing conditions.

Adult↗
PubMed1993

Long-term observation of the rat skin after fractionated local X irradiation: development of secondary tumors.

Data from previous animal experiments were analyzed retrospectively with a view to the induction of secondary tumors. The skin of 86 rats was exposed locally to multiple fractions of 200 kV p X rays at doses of 60 to 82 Gy applied in 30 or 35 fractions in 6 weeks, i.e., in the clinically relevant range of 1.9 to 2.7 Gy per fraction. The course of the early skin reaction was scored and compared to the late carcinogenic effects of the treatment using Kaplan-Meier data analysis. With increasing total dose the median duration of the early skin reaction increased, while median latency of tumor induction in the irradiated area of skin decreased from 381 days after 60 Gy to 274 days after 82 Gy. Independent of the total dose, number of fractions, and operative intervention, 84 to 100% of the animals cured by irradiation developed a secondary neoplasm inside the treated area. The majority of induced tumors were squamous cell carcinomas. In the skin covering the thorax, which had received a dose of 15 Gy in 10 fractions for elective irradiation of the lungs, no tumors were induced.

Animals↗
PubMed1992

Desensitization of histamine H1 receptor-mediated cyclic GMP production in guinea-pig lung.

Histamine H1 receptor-mediated production of cGMP in guinea-pig lung tissue becomes rapidly desensitized after previous exposure to histamine. This desensitization is clearly concentration dependent and appears to be homologous. Responses to histamine are also inhibited by previous treatment with phorbol 12,13-dibutyrate. Yet, the time course of the inhibition is considerably slower and the maximal inhibition is significantly less compared to receptor desensitization. Moreover, the effects of the phorbol ester are not confined to H1 receptor responses. Since the effects of receptor desensitization are also not prevented by several protein kinase C inhibitors, the development of homologous H1 receptor desensitization is not dependent upon protein kinase C activation, but is caused by a yet unidentified mechanism.

Animals↗
PubMed1992

Study on the epidemiology and control of Campylobacter jejuni in poultry broiler flocks.

Broiler flocks are frequently infected with Campylobacter jejuni. The origin of the infection is still unclear. The question of whether colonization of flocks results from transmission of C. jejuni from breeder flocks to progeny (vertical transmission) or from environmental sources (horizontal transmission) remains to be answered. Therefore, in this study samples were taken from successive broiler flocks in two broiler houses (house A on farm A and house B1 on farm B) as well as from the environment of the houses. All C. jejuni isolates were typed by using the Penner serotyping system, and part of the isolates from farm B were typed by using a randomly amplified polymorphic DNA-typing system. In poultry house A, C. jejuni was isolated from the first flock but not from subsequent flocks. In poultry house B1, C. jejuni strains of the same Penner serotypes and exhibiting identical DNA profiles were isolated from successive flocks. Infection of the flocks from a common source via horizontal pathways is suspected, while a vertical route of infection is not likely to exist. Application of measures to control horizontal transmission of C. jejuni on farm B was successful.

Animals↗
PubMed1991

Histamine H1-receptor-mediated cyclic GMP production in guinea-pig lung tissue is an L-arginine-dependent process.

Histamine produces a rapid and massive increase of the c-GMP level of guinea-pig lung tissue. The EC50 value for this in vitro response is found to be 27 microM and the c-GMP level is maximally 9-fold elevated by 100 microM histamine. The response is stereoselectively inhibited by the enantiomers of chlorpheniramine, indicating H1-receptor involvement. Preincubation of lung tissue with 200 microM NCDC, a phospholipase C inhibitor, reduces the histamine (100 microM) responses to 16 +/- 3% (N = 6) of the control c-GMP production. Inhibition of protein kinase C by 50 microM H-7 does not significantly attenuate the H1-receptor response, whereas omittance of extracellular Ca2+ results in almost complete inhibition of the c-GMP production. The histamine-induced c-GMP response is inhibited by hemoglobin, methylene blue and the antioxidants butylated hydroxytoluene and nordihydroguaretic acid, indicating the involvement of a nitric oxide-dependent activation of soluble guanylate cyclase. This suggestion is supported by the concentration-dependent inhibition of the c-GMP production by NG-monomethyl-L-arginine (NMA). At a concentration of 20 microM NMA the histamine (100 microM) response is inhibited to 34 +/- 8% (N = 6) of the control response. This inhibition is reversed to 127 +/- 20% (N = 6) by the exogenous addition of 1 mM L-arginine. These findings show that after an initial H1-receptor-mediated, phospholipase C-dependent, Ca(2+)-mobilization the enzymatic conversion of L-arginine to nitric oxide is stimulated. This nitric oxide production is finally responsible for the activation of soluble guanylate cyclase, leading to the production of c-GMP.

Animals↗
PubMed1991

Is protein kinase C involved in histamine H1-receptor desensitization?

Histamine H1-receptor mediated effects in guinea-pig lung and intestine appear to desensitize homologously rather rapidly. Within a few minutes of exposure to a high concentration of histamine (30-100 microM) the c-GMP production in guinea-pig lung and the contraction of guinea-pig jejunum are markedly attenuated. In both tissues the responses to other stimulating agents (e.g. muscarinic agent, calcium ionophore) are not affected. The protein kinase C (PKC) activating phorbolester phorbol-12,13- dibutyrate (PDB) concentration-dependently depresses H1-receptor responses in both tissues. Yet, PDB does not only attenuate the H1-receptor responses but also affects responses to other stimulating agents. In the guinea-pig ileum muscarinic receptor mediated contractions are inhibited equipotently by PDB, whereas in lung tissue the c-GMP formation after calcium-ionophore addition is affected too. In view of these findings the possible role of PKC in H1-receptor desensitization is discussed.

Animals↗
PubMed1991

DNA hybridization and latex agglutination for detection of heat-labile- and shiga-like toxin-producing Escherichia coli in meat.

DNA-hybridization and latex-agglutination tests were used for screening of a group of Escherichia coli isolates for heat-labile enterotoxin (LT)- and shiga-like toxin (SLT1 or VT1) -producing strains, respectively. Strains tested originated from 162 meat samples (poultry, pigs and beef) chosen at random. Additionally LT- and SLT1-producing reference strains were tested. The DNA-hybridization technique allowed screening of large numbers of strains, whereas large scale testing of strains by latex agglutination was laborious. Of 800 E. coli strains tested by DNA hybridization none contained the gene encoding LT. Production of LT as tested by latex agglutination was not found. The gene encoding SLT1 was detected in 10 of the 800 isolates tested. None of these strains, however, showed cytotoxicity on Vero cells. Serotyping was done with sorbitol-negative E. coli strains, first by using the latex-agglutination test for O157 followed by complete serotyping. No E. coli of serogroup O157 were found. Therefore the results obtained also indicate that routine screening of E. coli isolated randomly from food for toxin production is not useful and should be limited to food-borne disease outbreaks with an etiology resembling an E. coli infection.

Animals↗
PubMed1991

[Testing vision in children].

Measurement of visual acuity in children is more difficult than in adults. Children tend to riet when the threshold is reached and become inattentive. However the exact determination of visual acuity in children is important in some situations (Screening, Amblyopia). In this paper we examined whether an automated procedure is more exact than measurement by an examiner. Three series of experiments were done. In n = 173 we measured visual acuity first by an examiner using an optotype projector and second by an automated procedure (computer, keyboard, television screen). Both, the examiner and the computer used the same test-procedure and threshold criterion (DIN-Norm). The correlation coefficient was 0.84. In n = 53 children (age 4 to 7) visual acuity was measured by an examiner without a special strategy. Afterwards visual acuity was measured by the automated procedure. The correlation coefficient was 0.1. In n = 63 children (age 5-7) visual acuity was measured by an examiner using a strategy and a threshold criterion. Afterwards the automated procedure was used. The correlation coefficient was 0.69. The results show, that without a strategy and defined threshold criterion it is not possible to compare the measurements of visual acuity in different times. An automated procedure presented in this paper guaranties constant test conditions in an optimal way.

Adult↗