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M Wehrmann

Publications and source records attributed to M Wehrmann.

86 records · Page 5Linked to original sources
PubMed1989

[Effect of laser irradiation on atherosclerosis vascular segments in relation to wave length and pulse width].

The interaction of pulsed Nd:YAG laser radiation and atherosclerotic vessel wall is reported. The effects in the area of radiation were examined at an infrared, green, and ultraviolet wavelength at variable pulsewidths. The laser beam was focused directly on the plane surface of the tissue. The macroscopic and histologic examinations demonstrate that thermal damage of tissue is higher at an infrared wavelength than at a green wavelength and respectively at an ultraviolet wavelength. With increasing pulsewidth an increase of coagulation and necrosis of plaque material and adjacent vessel wall can be noted. The results show that for the precise ablation of plaque without adjacent vessel wall injury short pulsed ultraviolet radiation is preferable.

Angioplasty, Balloon, Coronary↗
PubMed1989

Long-term prognosis of chronic idiopathic membranous glomerulonephritis. An analysis of 334 cases with particular regard to tubulo-interstitial changes.

A retrospective long-term study (average follow-up time 5.2 years) of 334 patients with idiopathic membranous glomerulonephritis (MGN) was carried out with the following results: 1) MGN was found to have a relatively good prognosis when all cases were considered together: 5-year kidney survival rate (KSR) -88%, and 10-year KSR -77%. 2) Univariate survivorship analysis showed the following morphological and clinical parameters to be associated with an increased risk of terminal renal insufficiency or death from renal disease: a) tubulo-interstitial changes; b) glomerular stage III as opposed to stages I and II; c) elevation of serum creatinine concentration at the time of the biopsy; d) arterial hypertension at the time of the biopsy. 3) Multivariate analysis showed that only tubulo-interstitial changes (interstitial fibrosis and/or acute renal failure) found at the time of the biopsy and their clinical correlate, serum creatinine concentration, were significant and therefore of definite prognostic importance. 4) Unsystematic therapy with steroids and/or cytostatic agents does not improve the long-term prognosis of MGN. 5) The cause of disease in the tubulo-interstitial system in MGN is discussed. Interstitial fibrosis is considered to develop possibly as a consequence of unresorbed interstitial edema which can develop during an episode of acute renal failure. Coexisting T-cell-mediated disease in the region of the intertubular capillaries is also considered as a possible factor in the development of interstitial fibrosis.

Acute Kidney Injury↗
PubMed1988

Spectroscopic and hydrodynamic studies reveal structural differences in normal and transforming H-ras gene products.

We have recorded the circular dichroism spectra of the cellular and the viral H-ras gene products both in the absence and in the presence of guanine nucleotides and analyzed these spectra in terms of the secondary structure composition of these proteins. It is shown that the GTP complex of the ras proteins has a different secondary structure composition than the GDP complex and, furthermore, that there are differences in the secondary structure of the viral ras protein and the cellular ras protein. We have also recorded and analyzed the circular dichroism spectrum of the isolated guanine nucleotide binding domain of the Escherichia coli elongation factor Tu (EF-Tu), which has been considered as a model for the tertiary structure of the ras proteins [McCormick, F., Clark, B. F. C., LaCour, T. F. M., Kjeldgaard, M., Norskov-Lauritsen, L., & Nyborg, J. (1985) Science (Washington, D.C.) 230, 78-82]. Our data show that the guanine nucleotide binding domain of EF-Tu (30% alpha-helix and 16% beta-pleated sheet for the GDP complex) has quite a different secondary structure composition than the ras proteins (e.g., the cellular ras protein has 47% alpha-helix and 22% beta-pleated sheet for the GDP complex), indicating that the protein core comprising the guanine nucleotide binding site might be similar but that major structural differences must exist at the portion outside this core. Normal and transforming ras proteins also differ slightly in their hydrodynamic properties as shown by sedimentation velocity runs in the analytical ultracentrifuge.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Transformation, Neoplastic↗
PubMed1988

Transmission and scanning electron microscopy investigations on the structure of the ultrafilter of glomeruli in human acute renal failure.

In 4 cases of human acute renal failure (ARF) with oligo-anuria, normuria and polyuria the following findings were made. (1) The diameter of endothelial cell fenestrae is on average larger than that of the control values, but not significantly. (2) In ARF the ratio of the endothelial cell fenestral area to the total endothelial area is not significantly lower than in control kidneys. (3) In ARF the average density of fenestrae per unit of area is not significantly lower than in control kidneys. (4) The structure of the podocytes does not differ from that of control kidneys.

Acute Kidney Injury↗
PubMedDate not supplied

Neonatal rat cartilage has the capacity for tissue regeneration.

One of the most relevant issues in future medicine is tissue regeneration. Transplantation medicine alone cannot solve the problem of incurable conditions of vital organs. One approach to this might be the replication of the spontaneous regeneration that is found in embryonic/neonatal tissue. In this study, a tissue model for basic investigation of regeneration mechanisms in vivo was established. We demonstrated by histology and immunohistochemical staining for types I and II collagen that neonatal rat cartilage unlike adult cartilage has the capacity for rapid scarfree regeneration after full-thickness incision. The underlying mechanism was identified in the preserved proliferative capacity of neonatal chondrocytes. This in vivo model should prove useful in further studies of the role of cellular (e.g., GA cell cycle regulators) and extracellular (e.g., cytokines) factors in tissue regeneration and wound healing.

Animals↗
PubMedDate not supplied

Comparison of pulsatile and nonpulsatile perfusion of the lung in an extracorporeal large animal model.

OBJECTIVE: Extracorporeal lung-perfusion models are widely used to evaluate pulmonary preservation techniques and reperfusion injury. However, these models mainly depend on nonpulsatile flow, which is not physiological and can subsequently lead to pulmonary edema. Observation in a standardized setting and reliability of functional and structural data assessment are therefore limited. To overcome these limitations we developed a new extracorporeal large animal lung perfusion model utilizing pulsatile flow to perfuse the pulmonary vasculature. METHODS: Lungs of juvenile domestic pigs were in situ preserved with 2 liters Perfadex and stored for 3 h at 10 degrees C. Thereafter, reperfusion of the lung was performed in an extracorporeal blood perfusion circuit employing either a modified roller pump with pulsatile module (300 ml/min; pulsation rate 90/min) or a standardized roller pump with continuous flow (30 ml/min). Ventilation was performed with physiologic room air (350 ml; 16/min) for 1 h. Pulsatile and nonpulsatile perfusion was performed in 2 groups (group NP: nonpulsatile; group P: pulsatile flow, n = 7) during reperfusion. Peak inspiratory pressure (PIP), mean pulmonary artery pressure (PAP), and oxygenation capacity (DeltaPO(2)) were continuously measured. For control of the effectiveness of the pulsatile perfusion pressure waveforms were obtained directly from the native pulmonary artery of both groups. Malondialdehyde (MDA) as a parameter for lipid peroxidation and endothelial cell damage was assessed at 10, 30 and 50 min reperfusion. At the end of the study, pulmonary water content was assessed by means of wet-to-dry ratio (W/D ratio). The tissue was further processed for microscopic analysis. RESULTS: PIP increased significantly in both groups during reperfusion. Mean PAP in both groups increased to 60 mm Hg after 20 min followed by a decrease after 60 min to 40 mm Hg. Pressure waveforms of the pulmonary artery showed sufficient pulsatility in the pulmonary vasculature with a systolic/diastolic pressure difference of 15 mm Hg whereas the pressure difference was 3-5 mm Hg in the nonpulsatile group. DeltaPO(2) was stable in groups NP and P during reperfusion (30 min: NP: 66.4 (62.2-88) mm Hg; P: 74.8 (65-81.7) mm Hg) without any statistically significant differences between the groups. MDA in group NP decreased over the reperfusion period from 6.2 (3.3-6.3) microM at 10 min to 5.2 (3.2-6.1) microM at 50 min, whereas in group P the level increased and was significantly higher after 50 min reperfusion compared to group NP [6.6 (6.1-9.2) microM at 50 min; p = 0.016]. W/D ratio was 6.7 (6.3-7.0) in group NP and 6.8 (6.3-7.6) in group P. Light microscopy evaluation showed no differences between both groups regarding severity of intra-alveolar and interstitial edema and numbers of intra-alveolar, intracapillary and interstitial granulocytes. CONCLUSION: Although effective pulsatile perfusion of the pulmonary vasculature was achieved by means of a modified roller pump, this measure obviously did not improve functional parameters nor did it significantly reduce the edema formation after 3 h ischemia in this extracorporeal lung perfusion model. The use of pulsatile perfusion is therefore not mandatory in the extracorporeal setting of a large animal lung perfusion model.

Animals↗
PubMedDate not supplied

Effects of antihypertensive therapy on blood pressure and renal function in rats with hypertension due to chronic blockade of nitric oxide synthesis.

Different antihypertensive treatment regimes were studied in rats during long-term inhibition of nitric oxide synthesis. Male Munich Wistar rats (weight 150-200 g) were put on oral L-nitro-arginine methyl ester (L-NAME, 50 mg/l drinking water) for 12 weeks. The control group (n = 16) received only tap water. Six weeks after starting L-NAME administration rats were divided into 7 groups (n = 13 in each group: group 1, no treatment; group 2, l-arginine 1 g/l drinking water; group 3, doxazosin 30 mg/kg/day; group 4, felodipine 25-30 mg/kg/day; group 5, losartan 40 mg/kg/day; group 6, metoprolol 300-350 mg/kg/day, and group 7, ramipril 1 mg/kg/day. Systolic blood pressure (sBP) was measured in the conscious rat 1, 6, and 12 weeks after study begin. After a treatment period of 6 weeks albuminuria, glomerular filtration rate (GFR) and renal plasma flow (RPF; inulin and p-aminohippuric acid clearance) were analyzed. All rats showed a significant increase in sBP under 6 weeks of L-NAME administration. Control rats remained normotensive during the whole study period. Rats receiving L-NAME without antihypertensive treatment showed a further increase in sBP after 12 weeks. Blood pressure was lowered in all treated animals, except in rats receiving l-arginine. Values for GFR were lowest in the placebo group, the l-arginine group and in rats receiving felodipine (p < 0.05 compared to the control group). RPF was lowest in the placebo group, the l-arginine group, the felodipine group and the ramipril group (p < 0.05 compared to the control group).(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMedDate not supplied

Nephrotoxicity of cyclosporine A in the rat. II. Reversible changes in intranephronal and urinary catalytic activities of N-acetyl-beta-D-glucosaminidase.

Cyclosporine A (15, 30 or 50 mg/kg.day) or olive oil (30 mg/kg.day) were administered orally to 32 male Sprague-Dawley rats for 12 or 24 days, or withdrawn for 24 days following 24 days of treatment. The specific activity of a lysosomal marker enzyme, N-acetyl-beta-D-glucosaminidase, was determined fluorometrically in single nephron segments microdissected from lyophilized kidney sections of these animals and of an additional 2 normal rats. The segments were classified according to their normal or reduced succinate dehydrogenase activity as detected in stained adjacent sections. In addition, urine specimens collected after 12, 24, 36, and 48 days of the experiment were tested for N-acetyl-beta-D-glucosaminidase activity. After treatment with cyclosporine A, changes in the activities of N-acetyl-beta-D-glucosaminidase were found only in the proximal tubules. In the convoluted segments with normal succinate dehydrogenase activity, the activity of N-acetyl-beta-D-glucosaminidase was 138-163%, and in those with reduced succinate dehydrogenase activity, it was unchanged or 66-83% of the control values. In the straight segments with reduced succinate dehydrogenase activity, the activity of N-acetyl-beta-D-glucosaminidase increased gradually along the medullary rays (122-214%) to the outer stripe of the outer medulla (178-263%) in comparison to the control values. In the urine specimens, the activity of N-acetyl-beta-D-glucosaminidase was increased to 148-152%. These tubular and urinary changes were similar for each dosage and treatment period. After withdrawal of cyclosporine A they were not present. The variety of alterations occurring within the lysosomes along the proximal tubules of cyclosporine-A-treated rats implies the convoluted part as the site of increased release of N-acetyl-beta-D-glucosaminidase into the urine.

Acetylglucosaminidase↗
PubMedDate not supplied

Histologic effects of different technologies for dissection in endoscopic surgery: Nd:YAG laser, high frequency and water-jet.

Precise cutting combined with reliable coagulation of the margins of the lesion is an important requirement for dissection techniques in endoscopic surgery. These requirements are met by the two most common ancillary energy sources applied for endoscopic dissection today, electrosurgery and "thermal lasers", mostly the Nd:YAG. For the comparison of the histological effects of monopolar and bipolar high frequency with the Nd:YAG laser an experimental in vitro and in vivo study has been performed. In order to evaluate the advantages of non thermal dissection for endoscopic procedures, a water jet cutting system was included in the in vitro study. In parenchymatous tissue the water jet was found to be the least traumatic technique, followed by bipolar high frequency, laser and monopolar high frequency. The water jet was not applicable for intestinal dissection since uncontrolled bloating of the rectal wall with uncontrolled disruption of the tissue layers occurred. A general disadvantage is that secure haemostasis in the line of incision is hard to achieve. In the microscopic comparison of the shape of the incision, the Nd:YAG laser produced the smoothest lesions with well-defined margins. The monopolar technique was more often associated with irregular and sometimes fissured margins. These results were confirmed in the in vivo part of the study (Transanal Endoscopic Microsurgery).

Animals↗
PubMedDate not supplied

Rudimentary second stomach as adrenal incidentaloma.

We present the case of an adrenal incidentaloma of considerable size which turned out to be a stomach-like diverticular mass, probably a malformation arising from the embryonic foregut. We discuss whether results possibly obtained by extensive and costly investigative techniques would have changed the management.

Adrenal Gland Neoplasms↗