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Biomedical subjects

H Bartels

Publications and source records attributed to H Bartels.

At least 145 records · Page 8Linked to original sources
PubMed1989

Freeze-fracture study of the pavement cell in the lamprey gill epithelium. Analogy of membrane structure with the granular cell in the amphibian urinary bladder.

Freeze-fracture studies of the lamprey gill epithelium reveal structural differences of the luminal and basolateral plasma membrane of the pavement cells. The luminal membrane is characterized by only a few intramembrane particles on the P face and numerous large (10-13 nm) particles on the E face, whereas the basolateral membrane shows the majority of intramembrane particles (6-8 nm) on the P face. The structural specialization of the luminal membrane and the differences between the luminal and basolateral membranes of the pavement cell are similar to those previously demonstrated for the unstimulated granular cell of the amphibian urinary bladder. Because of this similarity, it is suggested that the 2 cell types are analogous and that the luminal membrane of the pavement cell in the lamprey gill epithelium is functionally characterized by a low water permeability. A possible role of sodium uptake by the pavement cells from freshwater and putative differences of osmoregulatory mechanisms in the gills of lampreys and teleosts in freshwater environments are discussed.

Amphibians↗
PubMed1988

[Surgery of acute pancreatitis. A problem of retroperitoneal sepsis?].

Of 99 patients with acute pancreatitis 31 had to be operated upon. Surgical intervention was indicated if, in the presence of pancreatic necrosis demonstrated by computed tomography, clinical evidence of sepsis developed. The operation was performed on average ten days after the onset of symptoms. Evidence of bacterial contamination of the pancreatic necrosis was obtained in 26 patients. The operation consisted of left pancreatic resection with formation of a left compartment. Four of the 31 operated patients died (12.9%).

Acute Disease↗
PubMed1988

Dependence of O2 transfer conductance of red blood cells on cellular dimensions.

To estimate the significance of the dimensions of RBC on O2 transfer, the kinetics of O2 release from RBC into medium containing dithionite (40 mmol/l) was measured, by a stopped-flow technique, for nine different species with varying RBC size (man, llama, vicuna, alpaca, dromedary camel, pygmy goat, domestic hen, muscovy duck and turtle). The observed O2 transfer kinetics were found to be size-dependent, i.e. the O2 transfer conductance of the single RBC, gst, was lower, whereas the specific O2 transfer conductance of packed RBC, Gst, or of whole blood, theta st, was higher for smaller RBC. The ratio of surface area to effective diffusion path length which was found to be about one fourth of the mean cell thickness irrespective of cell size and cell shape, may be considered as the essential morphological factor determining O2 transfer efficiency of the single RBC.

Animals↗
PubMed1988

Intercellular junctions in the gill epithelium of the Atlantic hagfish, Myxine glutinosa.

The intramembrane organization of the occluding junctions in the gill epithelium of the Atlantic hagfish, Myxine glutinosa, was studied by means of freeze-fracture electron microscopy. Mitochondria-rich cells, characterized by assemblies of rod-shaped particles in the luminal plasma membrane and by an extensive intracellular amplification of the basolateral plasma membrane, are singly distributed between the pavement cells in the gill epithelium of this marine and stenohaline cyclostome. The occluding junctions between mitochondria-rich cells and pavement cells do not differ from those between adjacent pavement cells, concerning the number of superimposed strands (median 6, range 4-9) and their geometrical organization. These observations suggest that, in contrast to marine teleosts, the paracellular pathway plays a minor role in transepithelial ion movements in the hagfish gill epithelium. The findings are in agreement with the absence of hypoosmoregulatory mechanisms in hagfish, as have been evolved in various marine vertebrates. In addition, small communicating junctions are demonstrated between pavement cells; they possibly serve for a coordinated synthesis and secretion of mucus by the pavement cells.

Animals↗
PubMed1988

Glycogen synthesis via the indirect gluconeogenic pathway in the periportal and via the direct glucose utilizing pathway in the perivenous zone of perfused rat liver.

The isolated liver from 24 h fasted rats was perfused in a non-recirculating manner in the ortho- and retrograde direction with erythrocyte-containing (20% v/v) media to provide adequate oxygenation of the liver. Glucose and/or gluconeogenic precursors were added as substrates. Glycogen formation was determined biochemically and demonstrated histochemically. With glucose as the sole exogenous substrate glycogen was deposited in the perivenous area, with gluconeogenic precursors it was formed in the periportal zone during ortho- and retrograde flow. When glucose and gluconeogenic compounds were offered together, glycogen was deposited in both zones. The results corroborate the model of metabolic zonation predicting that periportal glycogen is synthesized indirectly from gluconeogenic precursors while perivenous glycogen is formed directly from glucose.

Animals↗
PubMed1988

[En-bloc resection of the esophagus in esophageal cancer].

En-bloc esophagectomy not only comprises the elimination of the esophagus but also the mediastinal lymphadenectomy and the resection of the azygos vein and thoracic duct. Additionally the suprapancreatic abdominal lymphadenectomy is included and in tumors located orally of the tracheal bifurcation also the cervical lymphadenectomy. The surgical technique can be estimated as fully developed and standardized. Possible complications are postoperative hemorrhage (3.3%), chylothorax (1.6%) and tracheal lesions (4.9%). The mortality rate ranges under 10% in experienced centers, in our own patients around 6.6%. With en-bloc esophagectomy an exact staging of esophageal cancer becomes possible. In a high percentage complete tumor elimination (R0-resection) can be achieved and it seems that herewith prognosis in early tumor stages (T1/2N0/1) can be improved.

Carcinoma, Squamous Cell↗
PubMed1988

[The value of lymphography of malignant testicular tumors].

Between 1965 and 1968, 6500 lymphograms were performed at the University of Göttingen. Amongst these, there were 412 patients with malignant testicular tumours. In 81 patients the results of lymphography could be checked histologically. There was agreement between the lymphographic and histological findings in 65 patients (80.3%), sensitivity of 98.1% (51 out of 52) and specificity of 48.3% (14 out of 29). In 50 patients CT was performed in addition. The findings agreed in 31 cases; in eight patients lymphangiography resulted in a false positive finding and CT was incorrect in 12 patients. In all patients with proven retroperitoneal metastases, one or the other method produced a correct diagnosis.

Adult↗
PubMed1988

[Therapy of Hodgkin's lymphomas. Results of the German Hodgkin's Disease Study Group].

Between July 1983 and May 1987 143 untreated patients with Hodgkin's lymphoma in stages I-IIIA with risk factors qualified for the HD1 protocol, and 230 patients in stages IIIB/IV qualified for HD3. Patients in HD1 received a combined chemo-radiotherapy (2 x COPP + ABVD + 20 Gy EF vs. 40 Gy EF). Patients in HD3 received induction chemotherapy (3 x COPP + ABVD) and were randomized into consolidation by radiotherapy (20 Gy IF) vs. chemotherapy (1 x COPP + ABVD). In HD1, 73 of 89 evaluable patients (82%) achieved a complete remission. The survival of patients in stages I-IIIA with risk factors treated according to HD1 is as good as the survival of patients in stages I and II without risk factors. In HD3, 86 of 137 patients (63%) achieved complete remission after induction chemotherapy with 3 x COPP + ABVD. This is significantly better than the 31% complete remission rate observed in a pilot study with COPP alone (p less than 0.01). Including salvage therapy (radiotherapy in case of persisting nodal disease; chemotherapy with 4 x CEVD in case of persisting disseminated disease), a total of 76% complete remissions in stages IIIB/IVAB were achieved. An ESR greater than 80 mm/h was the most significant single risk factor in stages IIIB/IV for induction of CR and freedom from progression.

Adolescent↗
PubMed1988

Clonal gene rearrangement patterns correlate with immunophenotype and clinical parameters in patients with angioimmunoblastic lymphadenopathy.

T cell receptor beta (TcR beta) chain gene rearrangements have been reported in cases of angioimmunoblastic lymphadenopathy (AILD) and provided evidence for the presence of clonal T cell proliferations in this disorder. Twenty-three cases of AILD and two cases of hyperimmune reaction (HR) were investigated. In the two HR cases, essentially the same histologic pattern was present as in AILD but lymph node follicles were hyperplastic. Both HR cases showed germline configuration for the TcR and immunoglobulin heavy chain (IgH) genes. All other patients diagnosed with AILD had clonal rearrangements for TcR gamma and beta chain genes. In addition, seven out of these cases had clonally rearranged their IgH genes. These two different rearrangement patterns (TcR with or without Ig gene rearrangement) correlated to immunohistochemical and clinical data. Cases with TcR but without Ig gene rearrangements (group I) exclusively showed CD4+ proliferating T cells, whereas those cases with TcR and Ig gene rearrangements had significantly elevated numbers of CD8+ proliferating cells (group II). Group II patients significantly more often presented with hemolytic anemia and went into transient remission spontaneously or under steroid treatment. Group I patients, however, had a higher response to chemotherapy and a longer survival time. These data show that, based on different rearrangement patterns, it is possible to divide AILD into two different groups with distinct immunophenotypic properties and differences in clinical parameters. Immunogenotyping in AILD thus will have prognostic and therapeutic implications.

Adult↗
PubMed1987

Glycogen synthesis from pyruvate in the periportal and from glucose in the perivenous zone in perfused livers from fasted rats.

The isolated liver of 24 h fasted rats was perfused in a non-recirculating manner in the orthograde or retrograde direction with media containing glucose and/or gluconeogenic precursors. Glycogen formation was determined biochemically and demonstrated histochemically. With glucose as the only exogenous substrate glycogen was formed exclusively in the perivenous area during both orthograde and retrograde perfusion. With gluconeogenic precursors as the exogenous substrates glycogen was deposited in the periportal zone during orthograde perfusion and in the intermediate zone during retrograde perfusion. Supply of glucose and gluconeogenic substrates initiated glycogen synthesis only in the upstream region, i.e. in the periportal zone during orthograde and in the perivenous zone during retrograde perfusion. This localization of glycogen synthesis was probably due to an unavoidable, insufficient oxygen supply of the respective downstream area. In general, the results confirm the hypothesis that periportal and perivenous glycogen was synthesized from different substrates.

Animals↗
PubMed1987

Intramembrane aspects of myotendinous and myomuscular junctions: a freeze-fracture study of the gill sac-muscle of the Atlantic hagfish, Myxine glutinosa.

The intramembrane organization of the sarcolemma at the sites of myotendinous and myomuscular junctions was studied in the gill sac-muscle of the Atlantic hagfish, Myxine glutinosa, by using freeze-fracture replicas. At these sites rows of irregularly shaped particles (diameter approximately 6 nm) and short fibrils are present on the P face and a complementary pattern of grooves is present on the E face of the split plasma membrane. The center-to-center distance between adjacent rows of particles and grooves ranges from 12 to 20 nm. Rodlike projections being in register with the rows of particles and grooves, respectively, extend from the plasma membrane toward the extracellular space. These rodlike projections are also recognizable in thin sections, where they appear as spinelike projections (cross sections) or linear arrays (grazing sections) located in the lamina lucida of the basal lamina. The intramembrane particles are considered to be integral membrane proteins and to represent transmembrane links in a series of molecules by which intracellular actin filaments and extracellular collagen fibrils are connected across the plasma membrane. The rodlike projections are probably peripheral membrane proteins possibly connecting the plasma membrane with structural components of the basal lamina.

Animals↗
PubMed1987

Oxygen transfer properties and dimensions of red blood cells in high-altitude camelids, dromedary camel and goat.

To estimate the advantage of the small red blood cells (RBC) of high-altitude camelids for O2 transfer, the kinetics of O2 uptake into and release from the RBC obtained from llama, vicuña and alpaca were investigated at 37 degrees C with a stopped-flow technique. O2 transfer conductance of RBC (G) was estimated from the rate of O2 saturation change and the corresponding O2 pressure difference between medium and hemoglobin. For comparison, O2 kinetics for the RBC of a low-altitude camelid (dromedary camel) and the pygmy goat were determined and previously measured values for human RBC were used. O2 transfer of RBC was found to be strongly influenced by extracellular diffusion, except with O2 release into dithionite solutions of sufficiently high concentration (greater than 30 mM). The G values measured in these 'standard' conditions, Gst (in mmol X min-1 X Torr-1 X (ml RBC)-1) were: high-altitude camelids, 0.58 (averaged for llama, alpaca and vicuña since there were no significant interspecific differences); camel 0.42; goat, 0.42; man, 0.39. The differences can in part be attributed to expected effects of the size and shape of the RBC (volume, surface area, mean thickness), as well as to the intracellular O2 diffusivity which depends on the concentration of cellular hemoglobin. The high Gst of RBC of high-altitude camelids may be considered to enhance O2 transfer in lungs and tissues. But the O2 transfer conductance of blood, theta, equal to Gst multiplied by hematocrit (in mmol X min-1 X Torr-1 X (ml blood)-1), was only slightly higher as compared to other species: 0.20 (llama, alpaca, vicuña), 0.14 (camel), 0.18 (goat), 0.17 (man).

Altitude↗
PubMed1987

[Intestinal liberation and resorption of monosaccharides from carbohydrates of different degrees of polymerization. I. Relation between intestinal hydrolysis of carbohydrates and resorption of monosaccharides].

The study was designed to compare the intestinal absorption of monosaccharides from carbohydrates of different chain length. Furthermore, a correlation between the efficiency of hydrolysis of the polymers and the efficiency of the intestinal absorption was expected to be established. Glucose, the disaccharides maltose and sucrose and the polysaccharides maltodextrin DE 20 , maltodextrin DE 5 and starch were employed as substrates. The whole small intestines of anaesthetized rats were perfused in situ for 60 min with 0.5% solutions of these substrates in an open perfusion system. Initially 3-minute fractions of the perfusion medium, later 10-minute fractions were collected. The parameters determined were: secretion of pancreatic alpha-amylase activity, substrate hydrolysis (by alpha-amylase and by disaccharidases of the brush border membrane), intestinal absorption of the monosaccharides. alpha-amylase activity was significantly higher when the perfusion was carried out with starch solution. The possibility is discussed that this high-polymer substrate might stimulate the pancreas to an elevated alpha-amylase secretion. The highest rate of hydrolysis (45 mumol glucose/min) was determined from maltose as a substrate. The cleavage of the high-polymer substrates was less intensive. The hydrolysis of starch was limited by the capacity of the alpha-amylase, that of the sucrose by low activity of the saccharose. Absorption of glucose was more effective from the maltose solution than from the glucose solution. To understand this phenomenon, an additional "hydrolases-related transport system" could be taken into consideration. Glucose absorption from maltodextrin DE 20 was less effective than might have been expected from the rate of hydrolysis. This fact might possibly be explained by an inhibitory effect of oligosaccharides of chain length 4-10, contained in relatively high amounts in maltodextrin DE 20.

Animals↗
PubMed1987

[Intestinal liberation and resorption of monosaccharides from carbohydrates of different degrees of polymerization. II. Relations between monosaccharide resorption, blood glucose level and serum insulin concentration].

The small intestines of anaesthetized rats were perfused in situ for 60 min with 0.5% solutions of glucose, maltose, sucrose, maltodextrin DE 20, maltodextrin DE 5 or starch. Blood samples were repeatedly taken from the v. portae and the v. femoralis to estimate blood glucose and serum insulin levels as a function of perfusion time. The experiment was also performed to clarify whether a correlation exists between these parameters and the substrate uptake from the intestinal lumen (determined in the first part of the study). The highest glucose levels in v. portae and the highest portal-peripheral differences were found when glucose and maltose solutions were administered. Glucose levels in v. femoralis were almost independent of the substrate perfused. Perfusion with glucose caused a considerable insulin secretion starting immediately with the onset of perfusion. It was concluded that glucose might also stimulate insulin secretion on the intestinal level. Perfusion with maltose also effected a significant insulin output, the start of which was delayed however, compared with the effect of glucose.

Animals↗
PubMed1987

[Lymphography in malignant testicular tumors].

Experience and results are reported on the basis of more than 380 lymphographic investigations in patients with a malignant testicular tumor. In 61% of these patients, there was suspicion of a metastatic infiltration of the retroperitoneal lymph nodes. In 75 patients, histological checking of the lymphographic finding was possible on the basis of a retroperitoneal lymphadenectomy. Lymphography was shown to have a precision of 81%. Lymphography is obligatory as a complement to other techniques of investigation such as sonography and computer tomography in patients with malignant testicular tumor, since the greatest diagnostic information can be expected from combined application of all three methods.

Humans↗