Search PubMed⌕ Search

Biomedical subjects

R Baumann

Publications and source records attributed to R Baumann.

At least 145 records · Page 8Linked to original sources
PubMed1988

Membrane potential of primitive red cells from chick embryo is a proton potential.

The membrane potential of primitive red cells from 4- and 6-day old chick embryos has been determined using the fluorescent dye Dis-C3-(5). At day 4 the membrane potential Em was -44 mV for pH 7.4 and 20 degrees C and -36 mV at day 6. Both values are far removed from the equilibrium potential for chloride, which is about -14 mV at day 6. Changes in the external potassium, sodium or chloride concentration were without effect on the membrane potential, except at very high potassium concentrations, where a small but significant depolarization was observed at day 6. The measurements gave the same results in the absence or presence of the anion exchange blocking agent DIDS. Three pieces of evidence indicate that the membrane potential of primitive red cells is primarily caused by an electrogenic H+ conductance: 1) The measured membrane potential of -36 mV at day 6 is close to the previously determined proton equilibrium potential (Baumann and Haller, 1983) EH + of -36 mV. 2) Addition of the electrosilent Cl-/OH- exchanger tributyltin causes a significant depolarization of about 20 mV at day 4 and about 14 mV at day 6. 3) Measurement of hydrogen ion fluxes demonstrate a potential dependent proton conductance, which increases with depolarization. These results indicate that large qualitative differences exist with regard to the mechanisms involved in the generation of membrane potential and hydrogen distribution between red cell and plasma of embryonic and adult chicken.

Animals↗
PubMed1988

Oxygen pressure in intra- and extraembryonic blood vessels of early chick embryo.

Oxygen partial pressure (PO2) was measured in vitelline and intraembryonic vessels of 4- and 6-day-old chick embryos in ovo using recessed-tip oxygen microelectrodes. At day 4 mean PO2 values were 6 kPa in the vitelline arteries and 8.5 kPa in the oxygenated blood of the lateral vitelline veins. These values increased significantly by day 6 to 6.5 kPa in the vitelline arteries and 10.8 kPa in the lateral vitelline veins. The PO2 in intraembryonic arteries was found to be close to the PO2 in the vitelline arteries. In intraembryonic veins PO2 values ranged from 2.1 to 4.6 kPa displaying a gradient from cranial to caudal. Our measurements show that the major part of the diffusion resistance between environment and gas exchange vessels is formed by the albumen layer separating the yolk sac from the inner shell membrane, and that the oxygen transport is limited by diffusion. The low PO2 values in the intraembryonic venous vessels suggest that the gas transport system works at the limit of its capacity.

Animals↗
PubMed1988

[Quantitative hCG spot test of the serum and peritoneal fluid in intrauterine and tubal pregnancy].

The concentration of hCG was measured in serum and peritoneal fluid (PF) of women with normal intrauterine pregnancy (34), extrauterine pregnancy (21), and intrauterine abortion (12) by two different methods. A new rapid, quantitative method (Spot-Test; ICON-QSR) which provides the results within 10 minutes was compared to an immunofluorometric method requiring 90 minutes (IFMA). The serum concentration of hCG and the ratio of hCG in serum and in the PF correlated well when determined by both methods (p less than 0.001). Comparable results were also obtained when hCG was measured in the serum of 4 patients with extrauterine pregnancy for a period of 2 to 3 weeks before and after surgery. When hCG was measured by means of the spot test in samples of undiluted serum containing less than 30 IU/l, lower values were obtained as compared to the IFMA. In samples containing more than 200 IU/l, the relationship was reversed. In all cases of intact intrauterine pregnancy, the level of hCG in serum exceeded that in PF, whereas the converse was observed in 19 out of 21 tubal pregnancies. These results show the spot test to be suitable for the rapid and quantitative determination of hCG in serum and the PF, provided that there is no strong hemolysis in the samples. When the concentration of hCG exceeds 300 IU/l, the measurement has to be repeated with diluted samples. Differences in concentrations of less than 20% cannot always be distinguished. Even though the results of the present study are promising, the usefulness of the spot test for routine clinical practise has to be examined in further studies.

Abortion, Spontaneous↗
PubMed1988

Tubal anastomosis using a tissue adhesive.

The success of reversal of tubal ligation depends on the site of the sterilization, the tubal length after the repair of the Fallopian tube, the experience of the surgeon and the duration of surgery. It is therefore worth searching for methods to simplify the operation and to shorten the time necessary without reducing the success rate. We developed a method using a fibrin-thrombin adhesive system in combination with Swolin's one-stitch technique for tubal anastomosis. Instead of four to eight sero-muscular sutures we placed only one or two sero-muscular sutures and then the anastomosis was secured by a drop of fibrin glue. Until now 33 women have been 'refertilized' by this technique. In the case of 28 patients, a follow-up period of at least one year was possible. Thirteen intra-uterine pregnancies were achieved, three were ectopic and one woman aborted. In the cases of isthmic/isthmic anastomosis there were four intra-uterine pregnancies in six patients. We believe this result is a very important step to shortening the time of surgery with respect to the rules of microsurgical technique.

Anastomosis, Surgical↗
PubMed1988

[Treatment using lymphocytapheresis of severe forms of Crohn's disease. Preliminary results].

We report our experience in the treatment of severe Crohn's disease by lymphocytapheresis (LCTPH). Twelve patients with severe Crohn's disease unresponsive to prednisone for two years were treated by twelve sessions of LCTPH over a three-week period. Approximately 4.5 x 10(9) lymphocytes were removed at the end of each session, total lymphocyte removal per patient ranging from 1.9 to 10.7 x 10(8)/kg. Sessions were well tolerated. Clinical improvement was observed in all patients at the end of their LCTPH courses. However only fifty per cent of these patients achieved clinical remission of three months and for two of them the remission lasted 8 and 9 months. We examined the immediate effects of cytapheresis on peripheral blood lymphocytes and monocytes. No correlation was noted between the clinical efficacy of LCTPH and the quantity of lymphocytes (T3, T4, T8, NK) and/or monocytes removed. The only significant change was a partial recovery of NK activity in the good responders. The optimal modalities of depletion and the advantages of this treatment in severe Crohn's disease have to be defined in multicentric controlled studies.

Adult↗
PubMed1988

[Enteroclysis in chronic radioenteritis. Study of 43 cases].

Enteroclysis were practiced for 43 patients with radiation induced injuries of the small bowel. The radiological data revealed mucosal lesions in 23 cases, submucosa lesions in 21 cases, parietal thickening in 20 cases, mesenteric involvement in 32 cases. Narrowings and stenosis were present in 24 cases and dilated loops in 15 cases. Fistula formation existed in two cases. Twenty four patients were operated and the diagnosis of radiation enteritis was confirmed. In 12 cases, the enteroclysis succeed to a per os technique. The authors showed the superiority of the enteroclysis.

Adult↗
PubMed1987

Development of lumbar spinal cord and cortical evoked potentials after tibial nerve stimulation in the pre-term newborns: effects of gestational age and other factors.

Pre-term neonates are at increased risk for neurological dysfunction. Several investigators have found scalp recorded somatosensory evoked potential studies (SSEPs) after median nerve stimulation useful in the evaluation of newborn infants with asphyxiation and the effects of other adverse prenatal and perinatal factors. In order to evaluate the entire developing neuraxis, we undertook SSEPs after tibial nerve stimulation (PTN-SSEP) in pre-term neonates. Using bilateral simultaneous stimulation, potentials were recorded from the following sites: PF-spT6 (N5), spL1-spT6 (N16), spC7-Fpz (N27), Cz' (1 cm behind the vertex)-Fpz (P55). In all newborns studied, the N5 and N16 were reliably recorded. The N5 appeared relatively independent of the length of the newborns. The N16 correlated inversely with length. The N27 and P55 were recorded in 52% and 65% of the newborns, respectively. N27 inversely correlated modestly with length. The P55 was independent of most factors and probably reflects variable rates of cerebral myelination, neuronogenesis, varying states of alertness, and possibly subclinical encephalopathies. These results demonstrate the feasibility of obtaining such data in pre-term newborns.

Brain↗
PubMed1987

Substance P in human essential hypertension.

Substance P (SP) plays an important role in central nervous and peripheral blood pressure regulation. Its effects include modulating influence on the adrenergic system and inhibition of stress-induced plasma noradrenaline increase in animal studies. In patients with essential hypertension (n = 45, WHO stages 1 and 2) the SP-like immunoreactivity (SPLIR) was found significantly (p less than 0.01) lower (1.36 +/- 0.23 pg/100 microliters) than in 24 normotensive subjects (4.54 +/- 0.72 pg/100 microliters). Furthermore, the influence of a mental stress test on SPLIR was investigated in patients with essential hypertension (n = 11, WHO stage 1) and compared with nine normotensive subjects. Whereas in normotensive subjects plasma SP increased under a standardized mental arithmetic test (4.03 +/- 0.48 to 4.74 +/- 0.56 pg/100 microliters), in hypertensive patients a decrease of SP from lower baseline levels (2.85 +/- 0.54 to 2.57 +/- 0.54 pg/100 microliters) was demonstrated. The significantly different changes of plasma SP in normotensive and hypertensive subjects under mental stress conditions had the opposite direction in comparison with the adrenergic reaction [higher and prolonged increase of plasma noradrenaline (NA) in the hypertensive group]. Under antihypertensive drug treatment with prazosin (4.5 mg/day, n = 10) or with captopril (450 mg/day, n = 10) an increase of plasma SP was registered. The results support the participation of SP in the pathogenesis of human hypertension and in therapeutic mechanisms. Lower plasma levels and decreased responsiveness of SP possibly represent the enhanced stress sensitivity in primary hypertension.

Adult↗
PubMed1987

Functional properties of primitive and definitive red cells from chick embryo: oxygen-binding characteristics, pH and membrane potential, and response to hypoxia.

We compare properties of primitive and definitive red cells in three areas effect of different hemoglobin patterns on oxygen affinity cellular response to hypoxia, and red cell membrane potential and cell pH since during incubation blood pH decreases by 0.5 pH. We find that the first population of definitive red cells has many properties in common with the preceding primitive red cells. The oxygen-binding curves are nearly identical despite the fact that the definitive red cells contain only the adult hemoglobins A and D; in particular, n values greater than 4 are recorded in the upper saturation range. Within the definitive red cell population there is a drastic increase in the oxygen affinity between days 7 to 14. Hypoxia causes a series of coordinated changes in definitive but not primitive red cells, involving the phosphate pattern (2,3 DPG, ATP) as well as changes of carbonic anhydrase activity and oxygen affinity. The results suggest that the oxygen pressure controls part of the differentiation program of the definitive cell population and that control is dependent on plasma factors of high molecular weight. The membrane potential of primitive and early definitive red cells is a proton diffusion potential. During development proton conductivity decreases, and at day 16 proton and chloride distribution can be adequately described by the Donnan equilibrium. The linkage between membrane potential and proton distribution allows maintenance of red cell pH at about 7.2, irrespective of external pH, which greatly facilitates the adjustment of embryonic oxygen affinity.

2,3-Diphosphoglycerate↗
PubMed1987

[Congenital cystic dilatation of the common bile duct, anomaly of the biliopancreatic junction and cancer of the bile ducts].

The choledochus and pancreatic duct ordinarily enter the duodenum either separately or via a common channel located in the duodenal wall. The usual maximal length of the common channel is approximately 0.5 cm. An anomalous junction of the pancreaticobiliary tract is defined by the presence of an unusually long common channel whose length is 1 cm or longer. During the last 8 years, we studied 9 cases of congenital dilatation of the bile duct. Besides the choledochal cyst, all patients had a common channel which measured 1.5 cm or longer. The mean age of patients (6 females, 3 males) was 36.5 years. Three patients had extrahepatic bile tract carcinoma. One patient, a 51-year old man, had gallbladder carcinoma without stones while the two other patients, a 43-year old woman and a 32-year old man, had carcinoma arising from the wall of the cystic dilatation. These two patients had undergone a simple internal drainage procedure 16 and 8 years before, respectively. Our study suggests that the anomalous junction of the pancreaticobiliary tract, an embryonic anomaly which allows the reflux of pancreatic juice into the bile duct and gallbladder, may be responsible for congenital bile duct dilatation and biliary tract carcinoma. Total excision of the cystic dilatation and the gallbladder with hepaticojejunostomy is the appropriate surgical treatment.

Adolescent↗
PubMed1987

[Value of dapsone in the treatment of digestive manifestations of rheumatoid purpura in adults].

The authors report a case of adult rheumatoid purpura with severe gastrointestinal complications which responded extremely well to treatment with Dapsone. Although this drug has been reported to be effective in treating some forms of allergic vasculitis and the cutaneous manifestations of rheumatic purpura, there have not been any previous reports of its beneficial action in the treatment of the gastrointestinal complications of rheumatoid purpura. The mode of action is not fully understood. Dapsone could constitute a valuable therapeutic option together with steroids, parenteral nutrition and plasmapheresis in the treatment of the gastrointestinal complications of rheumatoid purpura.

Aged↗
PubMed1987

[Specific gastric localization of Wegener's disease].

We report an unusual gastric ulcer disease in a 52 year old white man which relapsed despite antacids and anti-H2 treatment. During the course of the disease, fever, weight loss, and ocular, oropharyngeal as well as systemic manifestations occurred. Gastric biopsies were normal until macrobiopsy was performed 5 months later demonstrating necrotizing granulomatous vasculitis. Further identical oropharyngeal mucosal lesions and a pulmonary infiltrate occurred supporting the diagnosis of Wegener's disease. The subsequent course was complicated by a massive hemorrhage which required total gastrectomy. Despite specific treatment with cyclophosphamide and steroids, the patient died. Most of the gastrointestinal lesions consistent with Wegener's disease are usually found at necropsy. Clinical gastrointestinal manifestations are scarce and rarely due to the underlying disease. Prognosis depends upon the renal lesions. However, as well, involvement of the digestive tract seems to be a factor of poor evolution of the disease.

Biopsy↗
PubMed1987

Oxygen supply of early chick embryo in normoxia and hypoxia.

The oxygen partial pressure (PO2) was measured in the large vessels of the yolk sac of 4- and 6-day old chick embryos using recessed-tip oxygen microelectrodes. The eggs were either incubated in air or in a hypoxic gas mixture (13.5% O2/86.5% N2). For the measurements, a part of the eggshell and the shell membranes were removed. Between 4 and 6 days of development, the mean PO2 in the anterior and posterior vitelline veins, which is approximately equal to the PO2 of the blood leaving the gas exchange vessels, was about 12 kPa (92 torr) in the normoxic group and about 9.3 kPa (70 torr) in the hypoxic group, suggesting that oxygen transport is diffusion-limited. The mean PO2 in the vitelline arteries, which are supplied by the dorsal aorta, was found to be in the range of 6-6.5 kPa (45-49 torr) in both normoxia and hypoxia. Taking into account that the eggshell and the shell membranes form an additional diffusion resistance, we have evaluated the PO2 and oxygen saturation of the blood of intact normoxic and hypoxic embryos.

Animals↗
PubMed1987

[Scintigraphy and esophageal pH measurement in adults with gastroesophageal reflux].

Thirty-seven adults with gastroesophageal reflux were explored by gastroesophageal scintigraphy and pH monitoring (three hours postprandial). Scintigraphy was less frequently positive than pH test in gastroesophageal reflux (81% versus 57%) with a significant difference. It is suggested that postprandial pH monitoring is reliable in the initial assessment of symptomatic gastroesophageal reflux.

Adult↗