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Biomedical subjects

M Friedrich

Publications and source records attributed to M Friedrich.

At least 199 records · Page 11Linked to original sources

Hypertrophic obstructive cardiomyopathy as a manifestation of a cardiocutaneous syndrome (Noonan syndrome).

The case of a 50-year-old patient with hypertrophic obstructive cardiomyopathy is reported. The patient demonstrated somatic signs of the Turner phenotype, but a cytogenetically normal karyotype was shown. These findings were compatible with the diagnosis of Noonan syndrome. The most commonly diagnosed cardiac disease in this syndrome is pulmonary stenosis, followed by hypertrophic cardiomyopathy. The patient's prognosis is limited by the natural history or the typical complications of the underlying cardiac lesion.

Cardiomyopathy, Hypertrophic↗

Alterations of ionic currents after reoxygenation in isolated cardiocytes of guinea-pigs.

Single myocytes were isolated from ventricles of adult guinea-pig hearts. The patch-clamp technique in the whole-cell configuration was used to study ionic currents. Experiments were performed in an experimental chamber that allowed the cells to be exposed to a sufficiently low O2 pressure to cause metabolic inhibition after 4-35 min (mean 14.1 min, n = 20), which was indicated by the appearance of a large time-independent K current. Reoxygenation about 1 min after the first extra outward current was observed caused this current to vanish completely within 2-6 s if the calcium inside the pipette was buffered to negligible values with 20 mmol/l EGTA. With only 10 microM EGTA in the pipette, reoxygenation was followed by an arrhythmogenic period of 10-150 s duration, which was dominated by three types of event: (a) transient inward currents (Iti) developed during the first 5-10 s (26 cells); (b) the net current was increased by a factor of 1.9 +/- 0.4 (mean +/- SD, n = 17) yielding a reversal potential for the increased component of -77 +/- 4 mV (mean +/- SD, n = 4); and (c) the Ca current decreased by 20%-100% within the first 5-10 s. At the end of the arrhythmogenic period, Iti vanished, the net current recovered completely, and the Ca current recovered partially. At -45 mV, increasing preceding depolarization enlarged the amplitude of both the Iti and the net current, Iti being about four times more increased than the net current. The suppression of the Ca current was independent of the phase of the preceding Iti. We conclude that in isolated cardiocytes, after the induction of an anoxia-induced K current, reoxygenation causes a period of up to 150 s of cytosolic Ca overload, during which Iti is triggered, the net current is enhanced, and the Ca current is suppressed.

Animals↗

Reoxygenation-induced arrhythmogenic transient inward currents in isolated cells of the guinea-pig heart.

Transient inward currents (Iti), activated by a rise in intracellular Ca concentration, are believed to trigger cardiac arrhythmias in reperfused hearts. In this report, Iti in isolated cardiocytes from the guinea-pig were evoked by reoxygenation following a period of anoxia of between 4 min and 35 min. Reoxygenation was performed 1 min after the full development of an anoxia-induced time-independent K current. This current disappeared within 2-6 s and in the following 10 s Iti developed to maximum amplitude. Iti were evoked using a constant pulse pattern (holding potential Vh = -45 mV; test potential Vt = +10; pulse duration 350 ms; frequency 1 Hz). In more than 95% of the cells, Iti at the holding potential Iti (-45 mV) declined with a time constant of tau = 670 +/- 240 ms (mean +/- SD, n = 17). In two cells, undamped oscillatory currents were observed. The amplitude of Iti (-45 mV) was proportional to the amplitude and duration of the preceding depolarizing test pulse. Test pulses of long duration (500 ms and 1000 ms, mean +/- SD) to potentials positive to +10 mV produced slowly decaying tail currents (tau = 391 +/- 51 ms, mean +/- SD), which superimposed with Iti (-45 mV). The current/voltage relationship of Iti peaked between -30 mV and -10 mV and approximated zero at the most positive potentials, i.e. no reversal of Iti was found up to +80 mV. Using double-pulse protocols (prepulse potential +40 mV), Iti were enhanced at potentials negative to -30 mV and were also present in the range of the normal resting potential of ventricular heart cells. The instantaneous current-voltage relationship was monotone between -50 mV and +40 mV. Because of the dependence of Iti on the preceding depolarization, the instantaneous current-voltage relationship provides more reliable information on the voltage dependence of Iti. The interval between two subsequent Iti (-45 mV) values was 237 +/- 35 ms (mean +/- SD, n = 27) and depended on the amplitude of Iti (-45 mV) to increase by 5.2 +/- 0.5% (mean +/- SD) per 100 pA decrease in Iti (-45 mV). A simple noise analysis showed that if one assumes that ionic channels are responsible for the generation of Iti (-45 mV), their unitary conductance cannot exceed 0.36 pS. We conclude that reoxygenation-induced Iti are triggered by a cyclic release of Ca from the sarcoplasmic reticulum and provide evidence that they are mediated by the electrogenic Na/Ca exchanger.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Anoxia opens ATP regulated K channels in isolated heart cells of the guinea pig.

We studied single channel ionic currents in cell-attached patches of guinea pig heart cells under conditions of anoxia (pO2 less than 0.1 torr) to identify the type of channels which contribute to the anoxia-induced time-independent K current in whole cells. In most experiments, K currents were recorded at negative potentials as inward currents with 150 mmol/l KCl in the pipette. After periods of 5-60 minutes of anoxia, opening events of one to four voltage-independent 83 pS channels developed whose open probability reached a steady state value between 0.6 and 0.95 (T = 35 degrees C). The reversal potential of the unitary currents, determined at 150 mmol/l and 10.8 mmol/l K+ in the pipette, showed that the channels were highly selective for K+ ions. Open time histograms were fitted by two or three exponentials of which the fast time constant (tau O1 = 0.46 +/- 0.20 ms, mean +/- SD) was bandwidth-limited by our filter and the slow components substantially varied (tau O2 = 1.5-19 ms; tau O3 = 23-200 ms). Voltage ramp experiments showed that the channels were slightly rectifying in an inward direction. The unitary conductance of anoxia-induced outward currents at reduced K+ in the pipette was smaller (11 pS at 5.4 mmol K+, 25 pS at 10.8 mmol/l K+) than in excised patches. It is concluded that in isolated cardiocytes substrate-free anoxia causes opening of ATP regulated K channels whose conductance is reduced at physiological levels of [K+]O by a fast block, most likely by intracellular Mg++ and Na+.

Adenosine Triphosphate↗

Transport of L-leucine hydroxy analogue and L-lactate in rabbit small-intestinal brush-border membrane vesicles.

Substitution of the alpha-amino group of amino acids by hydroxyl groups yields hydroxy analogues (HA), which have been ascribed beneficial effects in nitrogen-sparing diets for uremic patients. In this study, intestinal uptake of L-leucine HA (L-LeuHA) and L-lactate into rabbit jejunal brush-border membrane vesicles was investigated. An inward-directed H+ or Na+ gradient stimulated uptake of both labelled substrates in a voltage-clamped assay. The H+ gradient was the major driving force of uptake as compared with the Na+ gradient, and it led to a transient accumulation of both L-LeuHA and L-lactate. The proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) reduced the initial H(+)-gradient-driven uptake rates of both substrates, but was without effect on Na(+)-gradient-driven uptakes. The H(+)-gradient-driven L-LeuHA uptake was saturable (apparent Kt = 15.4 mM). Alpha-HA of L-leucine, L-isoleucine, L-valine, D-leucine, D-valine or L-lactate inhibited the H(+)-gradient-driven L-LeuHA or L-lactate uptakes whereas free branched-chain amino acids had no effect. Preloading the vesicles with one of the L- or D-HA of branched-chain amino acids or with L-lactate stimulated tracer L-LeuHA and also tracer L-lactate uptakes in the presence of a H+ gradient. It is concluded that H(+)-gradient-driven transport of L- and D-stereoisomeric HA of branched-chain amino acids as well as of L-lactate across rabbit intestinal brush-border membranes is mediated by the same carrier. Furthermore, there exists a Na+ gradient-driven L-lactate transport system in the rabbit intestinal brush-border membrane.

Animals↗

[Transport of the hydroxy analogs of leucine in the brush border membrane vesicles of the rabbit small intestine].

Hydroxy analogues of essential amino acids can be used in clinical nutrition to minimize nitrogen intake. In this study intestinal uptake of L-leucine hydroxy analogue into rabbit jejunal brush-border membrane vesicles was investigated. An inward directed H(+)-gradient was a driving force of uptake (pHoutside = 6.0; pHinside = 7.5) and led to a transient accumulation. The saturable system has a apparent transport constant Kt = 15.4 mM. By trans stimulation experiments it could be shown that both D- and L-stereoisomers of hydroxy analogues of branched chain amino acids as well as L-lactate share with the same H(+)-driven uptake system.

Animals↗

Evaluation of endosonography in TN staging of oesophageal cancer.

Strategies for the treatment of cancer of the oesophagus depend on the tumour stage at the time of diagnosis. Resection, the only curative treatment, is confined to early tumour stages. Tumours with local infiltration are usually unresectable and require palliative treatment. Computed tomography has been widely used for preoperative staging but often fails to define this correctly. Endoscopic ultrasound allows direct visualisation of the parietal wall and may be useful in staging gastrointestinal tumours. In a comparative prospective study, 52 patients with tumours of the oesophagus were investigated preoperatively both by endoscopic ultrasound and computed tomography to determine the stage of tumour infiltration and local lymph node involvement. Thirty seven of these patients underwent operation, resection, or dissection and entered the study. The intraoperative findings or the histopathological assessment, or both, were taken as a reference. For all TN stages of oesophageal tumours, correct preoperative staging was accomplished by endoscopic ultrasound in 89% for T stage and 69% for N stage compared with 51% and 51% respectively by computed tomography (highly significant using Fisher's exact test). This study shows that endoscopic ultrasound is useful in preoperative TN staging of tumours of the oesophagus.

Adult↗

[Elimination half life of the opiate etorphine].

In the capacity of an initial study both, the pharmacocinetics as well as the metabolism of etorphine were investigated. In a self-trial a bolus of 8 micrograms tritium-marked etorphine as administered intravenously and subsequently the half-lives in serum and urine were determined. To achieve this, etorphine and etorphineclucuronide were separated via HPLC and then quantified by measuring the radioactivity. The development of the concentrations was devided into 3 phases. Within the first phase half-lives of etorphine and etorphineglucuronide were found in the range of 0.3-1 hour in serum and, likewise, in urine. During the second phase the estimated half-life of etorphineglucuronide was 160-260 hours in serum as well as in urine. Within the last phase half-lives in urine were 47 hours for etorphine and 41 hours for etorphineglucuronide while the calculation of the half-lives in serum was not sufficiently feasible.

Adult↗

[Aneurysmal bone cyst of the thoracic spine].

A case of aneurysmal bone cyst of the thoracic spine is described. The value of the various imaging procedures in diagnosis of this benign bone lesion and its pathogenesis are discussed.

Bone Cysts↗

Chromate nephrotoxicity in developing rats. Significance of Cr(VI) reduction in rat kidney tissue.

Chromate reduction was studied in 9000 x g supernatant of renal tissue. It was shown that GSH plays an important role. Additionally, heat-sensitive factor(s) seem to be involved. Age differences in chromate nephrotoxicity parallel differences in chromate reduction in vitro. The lower reductive activity of young rats can be raised to adult values by GSH-addition. Fasting reduces GSH concentration, as well as chromate nephrotoxicity, in vivo.

Aging↗

[Rhabdomyolysis and a plexus lesion following heroin poisoning].

We report about a young female patient who suffered a rhabdomyolysis and a plexus lesion after heroin intoxication. A computer-tomography was made to reveal the extent of myonecrosis. A larger rhabdomyolysis of muscles of the pelvis and left thigh was seen. A residual paresis of the left N. peronaeus existed at discharge of the patient.

Adult↗

[Localized 31 phosphorus NMR spectroscopy of the human heart--development of a measuring method and initial clinical application].

In this work, the technique of 31P-NMR-spectroscopy is applied for the first time to diagnose coronary heart disease in patients, using a suitable measuring technique. In 13 healthy volunteers we applied a method comfortable and tolerable for patients, which enabled us to examine the myocardium inside the reception area of a surface coil. Concerning myocardium-specific selectivity and sensitivity the localization techniques FROGS (Fast-ROtating-Gradient-Spectroscopy), 1-D-ISIS (1-Dimensional-Image-Selected-In-vivo-Spectroscopy) and 3-D-ISIS were compared. By a combination of the 3-D-ISIS-technique with magnetic resonance imaging, we obtained a monitored position of the volume of interest (VOI) within the myocardium, thus gaining a selective measurement. The cube-shaped VOI with a lateral length of 50 mm was placed into the apical-septal area of the myocardium. On the basis of the obtained results, we examined seven patients suffering from coronary heart disease, which was symptomatic and verified by coronary angiography. The 31P-NMR-spectra of the two examined groups were computed into numbers representing the relative content of the myocardial high-energy-phosphates. In addition, the quotients PCr/ATP and Pi/ATP were calculated and compared. With this small number of cases the evaluation of the PCr/ATP-ratios already showed a significant difference of 0.34 (p less than 0.01) between patients with coronary heart disease (0.49 +/- 0.19) and healthy volunteers (0.83 +/- 0.27). The findings suggest the conclusion that 31P-NMR-spectroscopy is able to be instrumental in the diagnostic detection assessment of the metabolic state in coronary heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

[Hepatic hydrothorax without ascites].

A case of hepatic hydrothorax without clinical ascites is reported. The diagnosis was confirmed by intraperitoneal injection of 99mTc-tin colloid: scintigraphic images taken between 5 min and 18 h p.i. demonstrated a one-way transdiaphragmatic flow into the pleural cavity. The therapy consisted of diuretic treatment, pleural drainage and chemical pleurodesis, and resulted in prompt clinical improvement.

Adult↗

[Recombinant erythropoietin in autologous blood donation].

As a result of the AIDS crisis, public and physician pressure have increased the utilization of autologous blood products. Attitudes about homologous blood transfusion, however, have changed dramatically in recent years. A large segment of the population undergoing elective surgery is elderly and therefore has a significant incidence of cardiovascular disease and a slow response of the erythropoietic system when acute anemia occurs. However, preoperative autologous blood donation programs require 2-5 weeks to complete; the average yield is only 2.2 units per patient. As a consequence, autologous predonation is underused and homologous transfusion cannot be completely avoided in all patients. For several years recombinant human erythropoietin (rHuEPO) has been available and has been successfully used in the treatment of patients with renal anemia. This study evaluated the effect of r-HuEPO on patients with preoperative autologous blood collection. METHODS. Ten patients of both sexes scheduled for hip arthroplasty underwent a preoperative autologous program. During a period of 23 days prior to surgery autologous blood donation was performed with 7.5 ml/kg withdrawal on four occasions, the last one 5 days prior to surgery. Five patients were randomly treated with subcutaneous injections of rHuEPO (Erypo, Cilag GmbH, Sulzbach; Distributor: Fresenius AG, Oberursel, FRG) 200 IU/kg seven times, starting 3 days after the first blood withdrawal. All patients (n = 10) received oral iron therapy with iron sulphate 304 mg/die (= 100 mg iron/die). Patients with hypertension or recent myocardial infarction were excluded from the study. The hemoglobin level before donation had to be at least 11.0 g/dl. On each study day, a complete blood count and platelets, differential, and reticulocyte count were determined by standard methods as were transferrin, ferritin, and total iron-binding capacity. Blood loss and blood consumption during and after the operation were registered. The indication for blood transfusion (autologous/homologous) was based on hemoglobin values, which were not acceptable below 8.5 g/dl. RESULTS. No side effects of rHuEPO treatment were observed. Blood loss ranged from 650 to 1100 ml intraoperatively and 400 to 950 ml postoperatively with no differences between the groups. Patients with rHuEPO had no autologous red cell concentrates (aRCC) during the operation; two of them had two units of aRCC on the 2nd postoperative day. Two of the patients in the control group had intraoperative blood transfusions (2 and 3 units aRCC, respectively); all patients in this group were transfused postoperatively: 12 of the 20 units collected were utilized. At the onset of the operation the mean hemoglobin value in patients with rHuEPO was 13.5 +/- 0.4 g/dl compared to 11.3 +/- 0.3 g/dl in the controls. Reticulocytes increased significantly during the investigation period. On the 2nd, 3rd, and 4th days of autologous blood collection and before the onset of surgery, the number of reticulocytes was significantly greater in rHuEPO patients than in the controls. Further laboratory variables such as transferrin, ferritin, and total iron-binding capacity did not change significantly during the investigation period; there were no significant differences between the two groups. DISCUSSION. The results of the present study show that rHuEPO leads to an increase in reticulocytes with maintenance of hemoglobin levels during the phlebotomy program. As a consequence, patients with anemia and particular contraindications to homologous blood derivatives (irregular antibodies, Jehovah's Witnesses) may be able to undergo major surgery successfully. The possibility of shortening the intervals between phlebotomies would seem to be of major advantage; our data also suggest that an aggressive autologous blood collection program would increase yields over present programs. In our institute a minimum hemoglobin level of 11.5 g/dl is accepted for autologous donation.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Cell Count↗

Spinal cord monitoring during intraspinal extramedullary tumor operations (peroneal nerve evoked responses).

Longterm scalp recording of early SEP components triggered by peroneal or tibial nerve stimulation detects functional disturbances of spinal cord transmission due to mechanical trauma. We confirm previous observations that preoperative SEP patterns reflect neurological deficits and clearly show functional disturbances even on the side where they are not manifest. Peroneal nerve SEP have a well-known P40-peak corresponding to activities of neurons at the postcentral cortical layers. The P40-peak was identified in only 55% of our recordings. We therefore, tried to use the P50-peak that could be identified in 100% of the recordings under the difficult recording circumstances in the operating room. Other authors demonstrate that the P40 component varies spontaneously about 7 ms during operations; we found variation of P50-latencies of 9 ms. We found the P50 component to be a valid and reproducable SEP event for intraoperative monitoring. Decline of SEP amplitudes during the operation occurred especially during dissection of the tumor. We once found intermittent loss of the P50 component with complete recovery after several minutes. This study shows that peroneal nerve SEP monitoring during intraspinal tumor operations is a feasible and valid measure. It provides the surgeon with a new alarm parameter for spinal cord lesions.

Adult↗