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Biomedical subjects

H Köhler

Publications and source records attributed to H Köhler.

At least 217 records · Page 12Linked to original sources

[Influence of extrinsic denervation of the pancreas on food-stimulated pancreas secretion and cholecystokinin and neurotensin release in the dog].

In the present study we examined the effect of extrinsic pancreatic denervation on meal-stimulated pancreatic exocrine secretion and the release of neurotensin and CCK in dogs. Denervation of the pancreas significantly decreased protein output from preoperatively 16,661 +/- 1824 mg x 150 min to 2033 +/- 316 mg x 150 min postoperatively (p less than 0.001), and bicarbonate secretion from 297.5 +/- 36 mmol x 150 min to 104.85 +/- 16 mmol x 150 min (p less than 0.01). Release of neurotensin and CCK was not altered by interruption of the extrinsic pancreatic nerves. Our findings are consistent with the hypothesis that pancreatic secretory response to a meal is predominantly mediated by neutral extrinsic reflexes.

Animals↗

[Detection of the nucleolar activity in alveolar macrophages of swine].

With the help of the toluidine blue-staining-technique different characteristic shapes of alveolar macrophage nucleoli were detected, indicating differences in the rRNA synthesis activity of these cells. After application of a Pasteurella multocida aerosol the percentage of alveolar macrophages with a high rRNA synthesis increased. No correlation between the nucleolar activity and the efficacy of the clearance of aerogenously administered Pasteurella could be measured.

Animals↗

Synthetic peptides from a conserved region of gp120 induce broadly reactive anti-HIV responses.

In our efforts to identify products that might be used for active immunotherapy in human immunodeficiency virus (HIV) infection, we have studied synthetic peptides derived from the CD4 attachment site of gp120. Two peptides have emerged with particularly interesting properties. The first (B138) is linear and spans the envelope residues 421-438; the second (1005/45) encompasses amino acids 418-445 and is cyclized by way of a disulphide bond joining its terminal cysteines. Both species have been shown to inhibit syncytial formation in a conventional bioassay, B138 being the most efficient. Both peptides elicit high titres of anti-peptide antibodies in immunized mice, rabbits and goats, with titres exceeding 1:10(5) in many cases. A substantial portion of this response is directed against gp120 as determined by enzyme-linked immunosorbent assay (ELISA). Analysis by flow cytometry has demonstrated that the antisera are broadly reactive with multiple diverse strains of HIV. The anti-gp120 activity of the anti-peptide antiserum was further confirmed by radioimmuno-precipitation (RIP) assays. Furthermore, RIP analysis and inhibition experiments in a GD4-gp120 binding assay have revealed that anti-peptide sera contain antibodies directed against the CD4 attachment site on gp120 and interfere with this receptor-ligand interaction.

Animals↗

Generation and specificity of monoclonal anti-idiotypic antibodies against human HIV-specific antibodies. I. Cross-reacting idiotopes are expressed in subpopulations of HIV-infected individuals.

In this study we have generated monoclonal anti-idiotypic antibodies against human monoclonal and polyclonal anti-HIV antibodies in seropositive sera. A human anti-gp41 mAb (H2, IgM kappa) was used to immunize BALB/c mice and to prepare hybridoma anti-antibodies that react with H2 and not with normal human IgM. Similar monoclonal anti-antibodies were made in BALB/c mice immunized with Ig fraction prepared from a pool of HIV-seropositive sera. Both kinds of anti-idiotypic antibodies reacted with antibodies in pools of seropositive sera and with individual seropositive sera but not with normal human Ig or seronegative sera. The Id-positive Ig from single donors were isolated on two different anti-Id immunoabsorbents and shown to bind to p24 and gp120, respectively. The detection and isolation of idiotypically cross-reactive human anti-HIV antibodies from seropositive donors demonstrated, for the first time, the existence of shared Id expressed by antibodies against HIV Ag. The utility of cross-reacting anti-idiotypic antibodies as tools to dissect the network regulation of the anti-viral immunity in AIDS is discussed.

Animals↗

Evidence for non-V3-specific neutralizing antibodies that interfere with gp120/CD4 binding in human immunodeficiency virus 1-infected humans.

Total anti-gp120 antibodies (total anti-gp120 Abs) were purified from a pool of four human immunodeficiency virus-positive (HIV+) sera by affinity chromatography on a gp120SF2-Sepharose column and exhibited both type- and group-specific neutralizing activities. To dissect the epitope specificity of the group-specific neutralizing antibodies, CD4 attachment site-specific antibodies (CD4-site Abs) were isolated from total anti-gp120 Abs by using a CD4-blocked gp120SF2-Sepharose column. The CD4-site Abs exhibited group-specific neutralizing activities. Another approach to dissecting type- and group-specific neutralizing activities of total anti-gp120 Abs was to separate the third variable region (V3)-specific antibodies (V3-region Abs) from non-V3-region-specific antibodies (non-V3 Abs). The results indicated that V3-region Abs exhibited type-specific neutralizing activities, whereas non-V3 Abs exhibited group-specific neutralizing activities. By comparing the neutralizing activities of V3-region Abs to those of non-V3 Abs, we concluded that V3-region Abs are more effective than non-V3 Abs in neutralizing a specific HIV isolate. Collectively, this study indicates that group-specific neutralizing anti-gp120 antibodies are specific for the CD4 attachment site.

Acquired Immunodeficiency Syndrome↗

[An association of arterial occlusive disease with cyclosporine therapy after kidney transplantation].

Renal transplantation followed by immunosuppression with cyclosporine (whole-blood levels 200-300 micrograms/l) and methylprednisolone (4 mg daily) was performed in a 54-year-old man with chronic glomerulonephritis. Three years later rapidly progressive arterial obstructive disease (peripheral type) developed. Parenteral treatment with prostaglandins, calcium antagonists and nitrates, as well as a lumbar sympathectomy, was unsuccessful so that, in rapid succession, several amputations on upper and lower limbs became necessary. The disease progression was arrested only when azathioprine replaced cyclosporine. Raynaud's phenomenon, present at the time, also disappeared and analgesics were no longer required. Histological examination revealed severe Mönckeberg arteriosclerosis and thromboembolic occlusion of the affected vessels. The cyclosporine treatment, especially the hypercoagulability induced by it, and the Mönckeberg arteriosclerosis were thought to be significant factors in the pathogenesis of the rapidly progressive arterial disease. It is concluded that, in the presence of progressive arterial obstructive disease occurring under cyclosporine treatment, the replacement by other immunosuppressive agents should be considered.

Amputation, Surgical↗

[New aspects of large intestine surgery].

Use of the biofragmentable anastomosis ring led to no significant differences in clinical results when compared with the use of conventional suture techniques. The patients' prognosis and the efficiency of perioperative portal chemotherapy are impaired by perioperative blood transfusions in colorectal cancer. Regarding proved risk factors for development of local recurrence, there is no significant difference between low anterior resection and abdominoperineal excision. Lymph node dissection is one important factor for ensuring an adequate oncological strategy in colorectal surgery.

Colectomy↗

Total denervation of the pancreas does not alter the pancreatic polypeptide-induced inhibition of pancreatic exocrine secretion in dogs.

Pancreatic polypeptide (PP) is a potent inhibitor of pancreatic exocrine secretion in vivo. The mechanism of pancreatic inhibition by PP is unknown, but the absence of PP receptors on pancreatic exocrine cells makes a direct effect of this hormone on the gland unlikely. In this study, we investigated the hypothesis that PP exerts its inhibitory effect via extrinsic neural pathways. Ten dogs with gastric and pancreatic fistulas were given an intravenous infusion of 250 ng/kg-1 h-1 secretin and 50 ng/kg-1 h-1 caerulein over 3 h. One hour after starting the infusion, 400 pmol kg-1 h-1 porcine PP were administered over 1 h. Pancreatic bicarbonate and protein secretions were measured. Later, the pancreas was extrinsically denervated. PP infusion decreased bicarbonate secretion in the intact gland by 47% and in the denervated pancreas by 57%. Protein secretion was diminished by exogenous PP by 31% in the intact and by 44% in the denervated pancreas. Despite pancreatic denervation, PP still exerted a significant inhibitory effect. Atropine infusion completely blocked the inhibitory effect of PP on caerulein-stimulated pancreatic protein secretion both in the intact and denervated pancreas and of secretion-evoked bicarbonate output in the denervated gland. We conclude that the inhibitory action of the hormone is not mediated via extrinsic neural pathways of the pancreas, but PP may exert its effect via intrinsic atropine-sensitive mechanisms.

Animals↗

Autosomal dominant polycystic kidney disease--in vitro culture of cyst-lining epithelial cells.

The major form of autosomal dominant polycystic kidney disease (ADPKD) in humans is linked to the PKD1 gene on chromosome 16p. The identity of the gene and the underlying pathogenetic mechanisms are not yet defined. Cyst-lining epithelial cells derived from a polycystic kidney were successfully grown in culture and designated MZ-PKD-1 cells. By linkage analysis, the related pedigree of the nephrectomized patient could be linked to the PKD1 gene on chromosome 16p. Thus, these cells exhibit the genotype of a mutated PKD1 gene and represent an in vitro culture model for ADPKD involving chromosome 16p. The antigenic phenotype was characterized immunohistologically by epithelial differentiation antigens and markers of individual nephron segments. An essentially identical antigenic pattern of proximal tubular cells was observed both in vitro and in fresh frozen tissue. Electron microscopy showed the formation of a microvillous-like coating. During growth phases in vitro successive changes in the cell shape were observed. MZ-PKD-1 cells exhibited a limited lifespan ending in replicative senescence. Northern blot analysis of kidney-growth-related genes, c-myc, TGF-alpha, TGF-beta 1, and EGF receptor revealed abundant expression of all of these genes in MZ-PKD-1 cells.

Antibodies, Monoclonal↗

Antibodies of different specificities are self-binding: implication for antibody diversity.

Antibodies of the S107/T15 germline family possess variable region structures which allow them to form specific complexes. We extended the investigation of the immunochemical properties of self-binding antibodies (autobodies) to mutant antibodies: U4, which binds DNA, and U10, which has no identified antigenic specificity. U4 differs from the germline S107/TEPC15 autobody by one substitution in the variable heavy chain, which results in a loss of phosphorylcholine binding. Like TEPC15, U4 and U10 are also self-binding. While self-binding of the wild-type TEPC15 antibody is inhibited by free hapten phosphorylcholine self-binding of the anti-DNA antibody U4 is inhibited by DNA and by free nucleotides. The self-binding locus of U4 and U10 was further investigated using peptides derived from the variable region. A 22 residue peptide from the CDR2/FR3 variable heavy chain sequence of the TEPC15 germline structure specifically inhibits self-binding in solid-phase assays. Peptides from unrelated antibodies have no effect on self-binding. The finding of antibodies with identical specificities which are self-binding or not self-binding demonstrates the existence of a novel kind of antibody repertoire diversity controlled by variable sequence structures.

Amino Acid Sequence↗

Response of huSCID mice reconstituted with lymphocytes from anti-idiotype-treated melanoma patients.

Severe combined immune deficient (SCID) mice were reconstituted with peripheral blood mononuclear cells (PBMC) from normal and melanoma patients. The melanoma patients were part of a clinical trial of active immunotherapy with the murine monoclonal anti-idiotypic antibody, IMelpgl. IMelpgl represents an idiotypic mimic of the high-molecular-weight melanoma-associated antigen, HMW-MAA. All of the huSCID mice reconstituted fully as evidenced by their production of human immunoglobulins. Furthermore, approximately half of the huSCID mice reconstituted with PBMC from either normal or melanoma patients were able to mount a secondary response to tetanus toxoid. While all of the huSCID mice reconstituted with PBMC from patients undergoing immunotherapy produced strong HAMA responses, only one huSCID mouse responded idiotypically to IMelpgl immunization. These results demonstrate tht the huSCID mouse can be used as an experimental model to monitor and study the response of human B cells derived from patients undergoing active immunotherapy.

Animals↗

Acanthocyturia--a characteristic marker for glomerular bleeding.

Erythrocyte morphology by phase contrast microscopic examination (PCM) of the urine is widely employed in distinguishing glomerular from nonglomerular bleeding. The proposed percentages of dysmorphic red cells are significant for glomerular bleeding in the range of 10 to 80% in the literature, because there is no clear cut definition of "dysmorphism." In the present study midstream urine samples of 351 patients with hematuria (greater than 8 erythrocytes/microliters) and of 33 healthy controls were examined. The various dysmorphic red cells were analyzed by PCM according to a detailed hematological classification. Most of the dysmorphic red cells, such as echinocytes, anulocytes, ghost cells, schizocytes, stomatocytes, codocytes and knizocytes, occurred in glomerular or nonglomerular disease as well, and proved to be uncharacteristic for glomerular bleeding. In contrast, a unique red cell deformity, a ringform with vesicle-shaped protrusions (acanthocyte) closely correlated to glomerular disease. In biopsy proven glomerulonephritis acanthocytes comprised 12.4% of all excreted red cells, whereas in nonglomerular diseases or in healthy subjects acanthocytes were seen very rarely (less than 2%) or not at all. Acanthocyturia greater than or equal to 5% (of excreted red cells) was seen in 75 out of 143 patients with proven glomerulonephritis (sensitivity 52%) and in four out of 187 patients with nonglomerular disease (specificity 98%). To improve the diagnostic value of erythrocyte morphology the diagnostic workup should focus on acanthocyturia, which is also indicative in very low erythrocyte counts.

Acanthocytes↗

Plasma concentrations of neurotensin and CCK in patients with chronic pancreatitis with and without enzyme substitution.

The peptide hormones neurotensin (NT) and cholecystokinin (CCK) are commonly attributed with a physiological role in the stimulation of exocrine pancreatic secretion. However, on the other hand, little is known about the effect of diminished exocrine pancreatic function and of the resulting maldigestion on postprandial plasma levels of these two gastrointestinal peptides. We investigated, therefore, the effect of enzyme substitution therapy on the magnitude and time course of plasma concentrations of both hormones in patients suffering from severe chronic pancreatitis. Pancreatic insufficiency led to elevated NT-concentrations, in response to a standard meal, which could be reduced by enzyme replacement therapy. Prior to enzyme therapy, the mean integrated postprandial release of NT amounted to 2800 +/- 250 pg/ml after 60 min in patients with severe chronic pancreatitis. This amount was significantly reduced to 1250 +/- 150 pg/ml after 60 min after enzyme therapy, compared to 810 +/- 90 pg/ml after 60 min in healthy volunteers after the standard meal. The integrated postprandial CCK level in patients investigated was significantly lower (35 +/- 4.8 pmol/L after 60 min) without any substitution therapy, compared to the integrated peptide amount in healthy volunteers (145 +/- 13.5 pmol/L after 60 min). Enzyme therapy in patients suffering from chronic pancreatitis led to an increased postprandial CCK-level (80 +/- 9.6 pmol/L after 60 min). Elevated CCK-plasma concentrations have not been demonstrated in these patients with pancreatic insufficiency. We therefore suggest that CCK might not play a major role in feedback regulation in patients with chronic pancreatitis. However, in light of elevated NT plasma concentrations in patients with chronic pancreatitis, NT-mediated influence on the pancreas deserves further study.

Amylases↗

Human anti-phosphorylcholine antibodies share idiotopes and are self-binding.

We have previously shown that BALB/c antipneumococcal polysaccharide antibodies with phosphorylcholine (PC) specificity are self-binding, mediated by hypervariable sequence structure of the heavy chain. We extended the observation of self-binding anti-PC antibodies to naturally occurring human anti-PC antibodies. Anti-PC antibodies were purified from normal donor sera and shown to bind to monoclonal antiidiotypic anti-T15 antibodies originally raised against the murine T15 idiotype. These human antibodies are self-binding which is inhibitable by the PC hapten and the murine T15 (50-73)-derived Vh peptide. The anti-PC antibodies were further separated into id-positive and id-negative anti-PC antibodies. Only the T15 id-positive preparation was self-binding. These findings demonstrate an evolutionary, conserved biological property between mouse and man associated with a naturally occurring antibacterial antibody. This conserved biological and structural property may have been selected in evolution because it is part of an important immune defense mechanism against bacterial and other environmental pathogens.

Amino Acid Sequence↗

Anti-idiotype monoclonal antibodies as vaccines for human cancer.

The anti-idiotype therapy approach has been tested and has shown to be effective in several animal models including the L1210/GZL tumor system in DBA/2 mice. Very recently, anti-idiotype antibodies (Ab2) have also been used in human trials. In this review, the generation and characterization of Ab2s which can be used as potential vaccine candidates for two human tumor systems--leukemia/lymphona and gastrointestinal carcinoma have been discussed. We have generated syngeneic monoclonal idiotypic cascades for two different human tumor-associated antigens (TAA) gp37 and carcinoembryonic antigen (CEA). In both cascades we have produced TAA mimicking monoclonal Ab2s and monoclonal anti-anti-idiotypes (Ab3) which bind to the original TAA. Modulation of immune responses in cancer patients by Ab2 immunization will be an important consideration in future studies.

Antibodies, Anti-Idiotypic↗

[Helicobacter pylori colonization in surgical patients].

The prevalence of Helicobacter pylori (HP) was examined in 387 patients undergoing endoscopy of the upper gastrointestinal tract. Of central interest was the question to which extent surgical intervention influences the colonisation of the gastric mucosa with HP. The bacillic status was appraised using double microbiological examinations, histological determination and the CLO-test. In 229 patients a 13C-urea-breath test was also carried out (sensitivity 98%). HP could be detected in 90% of all patients presenting with duodenal ulcers as well as in 70% of patients with gastric ulcers, whereas in those patients in whom a lesion of the upper gastrointestinal tract could be excluded through endoscopy. HP was found in only 27%. The prevalence of HP did not increase with age. In patients having undergone distal gastric resection due to gastric ulcers, HP was only rarely found (19%) in the mucosa in the vicinity of the anastomosis following removal of the apparently pathogenetically important antrum mucosa. There was no association between anastomosis ulcers and bacillic colonisation. Following selective proximal vagotomy in patients with duodenal ulcers, HP was found in 80% of all cases. In these patients there was also no association between recurrent ulceration and a HP-positive status. Our results describe the postoperative HP-status after different surgical procedures of ulcer therapy: whereas a distal gastric resection removes the antrum mucosa, which provides the necessary environmental milieu, the HP-colonisation rate after selective proximal vagotomy is similar to that in non-operated ulcer disease.

Adolescent↗