Biomedical subjects
Publications and source records attributed to J Köhler.
We describe one case of myeloid metaplasia with a dup(1q21 leads to 1q32), one case of myelomonocytic leukemia with a deletion of 11p (11p12 leads to 11q14), and a case of polycythemia vera with a deletion of 11q (11q14 leads to 11q25) and a presumptive duplication of 1q (1q25 leads to 1q44) via translocation to 6pter.
A novel type of radiometer is described, which solves the problem of emissivity-(mismatch)-independent noise temperature measurements by simultaneous registration of an object's apparent temperature and its reflectivity with just one microwave receiver and real-time calculation of the object's emissivity and its actual temperature.
Ubiquinone-9, an ubiquinone with a side-chain containing 9 prenyl residues, was purified from Hyphomicrobium spec. strain ZV 580, and identified by thin-layer chromatography, UV spectroscopy, and mass spectrometry. The participation of the quinone in the reactions of the respiratory chain was established by observing its increasing reduction in a membrane fraction upon the addition of NADH, the exhaustion of oxygen, and in the presence of NADH plus cyanide. The degrees of reduction in these states matched those of the cytochromes b and c.
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Because of insufficient opening of Björk-Shiley- and Lillehei-Kaster-prostheses in vitro and in vivo a new pendulum valve is proposed. The skeleton line of the disc crossection is bent towards the main flow direction when the valve is closed. Thus during valve opening the blood stream is directed to the opposite of the opening direction as to add torque to the disc which enables complete valve opening. During flow observations in an open water table with eight different curved discs an increase of the opening angle with which the torque disappears could be measured with increasing curve of the disc. The pressure loss of the valve is smaller in comparison to the pressure loss of pendulum valves with plane or contrarily curved discs. Furthermore the curvature decreases the backflow volume during valve closure.
The calculation of opening areas of artificial valves by the Gorlin-formula results only in small areas. This is why the converting factors of artificial valves are unknown. In addition, the flow characteristics are different from those of native valves and do not correspond to the conditions necessary for the Gorlin-formula. According to the narrowest flow diameter, however, in all artificial valves the areas can be calculated from volume-time curves and pressure gradients at the moment of maximum flow. In addition, in tilting disc valves the opening area can be estimated from the angle of the opening disc during time of steady flow.
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Excretion of oxalic acid in urine was measured in 28 healthy and 97 patients with gastrointestinal diseases. We found significantly higher values in the following groups: patients after resection of parts of the small intestine, patients with sprue and other diseases with malabsorption, patients with M. Crohn of the small intestine, colitis ulcerosa and granulomatosa, patients with chronical diseases of the pancreas gland and patients with cirrhosis of the liver. In 4 patients after resection of parts of the small intestine or pancreas urolithiasis could be verified. Reduction of fat and food without ballast reduced the excretion of oxalic acid in urine. Hyperoxaluria correlied significantly with the following parameters: excretion of fat in feces, exhalation of 14CO2 in the glykocholate breath test, resorption of vit. B12 and the length of resected small intestine. This form of hyperoxaluria is caused by hyperresorption of oxalic acid from food. The mechanism of this hyperresorption is not clarified yet, an important factor seems to be ill resorption of fat.
Urinary oxalate excretion was measured in healthy persons and patients with Crohn's disease, colitis ulcerosa, sprue and other diseases accompanied with malabsorption, and patients with insufficiency of the exocrine pancreas gland. Further measurements were made in patients after resection of parts of the small intestine or the colon. We found a clear increase of urinary oxalate excretion in patients with resected parts of the small intestine, sprue or other malabsorption syndromes. In 4 patients with resected parts of small intestine or pancreas we even found urolithiasis. Urinary oxalate excretion correlated significantly with steatorrhoea and increased if larger parts of small intestine were resected. Increased resorption of oxalate from food causes increased urinary excretion. Details about the patho-mechanism of this increased excretion are not known yet; an important factor seems to be the reduced absorption of fat in the small intestine.
The effect of renal artery stenosis on the poststenotic hemodynamics is demonstrated and evaluated in the presented experimental and clinical investigation. It is shown that the resistance of a medium sized stenosis is small compared to the total renal resistance. The peripheral resistance which is induced by the stenosis is the essential characteristic in the pathophysiology of the renal artery stenosis and the resulting hypertension. The increasing pressure can be measured primarily in the stenosed artery and later also in the not stenosed side and is seen as an effect of the renin-angiotensin-mechanism. The renal artery flow returns to normal after removal of the experimental stenosis. Likewise the reduction in renal artery flow is normalized by resection of the stenosis in the initial phase of the clinical renal artery stenosis. The induced hypertension is reversed to normal. Since the resistance in the initial phase is essentially limited to the stenosed side the global renal resistance is only little increased. Increased total renal resistance is due to morphological changes in the peripheral vessels. The removal of the stenosis will not be followed by a decrease in bloodpressure. This is to be seen in the data of our clinical cases. The critical limit for an effective operation followed by a decrease in artery pressure is to be seen in a total renal resistance of over 0.25 mm Hg/ml min-1.
A model of a pulsatile cardiovascular system is described including an electronic control, a hydraulic driving unit, a volume storage, a peripheral resistance and measuring equipment. Six different artificial heart valves, a designed aortic valve (Aachen pockett valve II) and a human aortic valve have been tested in the outflow position of the pump. Three of them are presently being used in clinical applications. Measurements of pressure and volume flow have been obtained for different frequencies n, pump volumes Vp and time ratios between pressure and suction phase. From the experimental results a comparative evaluation was deducted for different working conditions. In comparison to natural human aortic valve (NK) large volume flow is verified by the Aachen pocket valve II (AT), the Gott-Dagget value (GD), the Starr-Edwards valve (SE) and the Lillehei-Kaster valve (LK). The Gott-Daggett valve has the smallest back flow volume. The Smeloff-Cutter and in particular the Wada-Cutter valve have the largest regurgitation. This is to be expected since the Cutter valves are purposely so designed that they do not close tightly in order to avoid blood sedimentation. The human aortic valve, the Gott-Daggett valve and the Aachen pocket valve demonstrate the most favourable opening-closing characteristics. The human aortic valve achieves a negligible pressure loss, followed by the Björk-Shiley and the Lillehei-Kaster valve.
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