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Biomedical subjects

M Schilling

Publications and source records attributed to M Schilling.

At least 73 records · Page 4Linked to original sources
PubMed1996

Clenbuterol protects mouse cerebral cortex and rat hippocampus from ischemic damage and attenuates glutamate neurotoxicity in cultured hippocampal neurons by induction of NGF.

It has been shown previously that clenbuterol, a beta 2-adrenergic receptor agonist, enhances NGF synthesis in adult rat brain. Since NGF is able to protect neurons against damage, we tried to find out whether clenbuterol can rescue cultured hippocampal neurons from excitotoxic damage by induction of NGF. The neuroprotective activity of clenbuterol on neurons in the vulnerable CA1 subfield of the hippocampus was tested in a rat model of transient forebrain ischemia. Additionally, in the mouse model of focal cerebral ischemia the ability of clenbuterol to reduce the infarct size was examined. Exposure of mixed neuronal/glial hippocampal cultures to clenbuterol (1 to 100 microM) enhanced significantly the content of NGF measured in the culture medium by two-site ELISA. The excitotoxic injury was induced in the same type of cells after 14 days in vitro by exposure to 1 mM L-glutamate for 1 h in serum-free medium. NGF itself (0.15 to 100 ng/ml) added to the growth medium 4 h before until 18 h after induction of injury (the point of glutamate-toxicity measurement), protected hippocampal neurons from excitotoxic damage. Clenbuterol (1 to 100 microM) provided similar neuroprotection as NGF under the same experimental conditions. The neuroprotective activity of clenbuterol (100 microM) against glutamate-induced damage in hippocampal cultures was blocked by anti-NGF monoclonal antibodies (0.5 microgram/ml) added to the medium during the clenbuterol exposure, demonstrating that the neuronal rescue is mediated by NGF. Propranolol, a beta-adrenergic receptor antagonist (10 microM) added 20 min before and kept in the medium during exposure of the cultures to clenbuterol (1 microM) reversed the neuroprotective activity, suggesting that the induction of NGF and neuroprotection caused by clenbuterol are mediated via beta-adrenergic receptor activation. The capacity of clenbuterol to protect hippocampal neurons was also demonstrated in vivo in a rat model of transient forebrain ischemia. Clenbuterol (4 x 1 mg/kg) administered intraperitoneally increased the number of viable neurons in CA1 subfield of the rat hippocampus. Furthermore, clenbuterol (0.3 and 1 mg/kg, i.p. and 1 mg/kg, s.c.) reduced significantly the infarct area on the mouse brain surface after occlusion of the middle cerebral artery. The present data demonstrate that clenbuterol induces NGF synthesis in cultured hippocampal cells and protects hippocampal neurons from excitotoxic damage. The neuroprotective activity of clenbuterol is also demonstrated in vivo in two rodent models of cerebral ischemia. The results offer strong evidence that the neuroprotective activity of clenbuterol is caused by activation of beta-adrenergic receptors and the subsequent increased expression of NGF.

Animals↗
PubMed1996

Immunocytochemistry and flow cytometry evaluation of human megakaryocytes in fresh samples and cultures of CD34+ cells.

Adhering platelets on the cell surface can give misleading results when doing flow cytometry analysis of platelet/megakaryocyte-specific glycoprotein (GP) antigens to enumerate megakaryocytes (MK) in mobilized peripheral blood (PB), apheresis products, or normal bone marrow (BM). For adequate quantification and characterization of human MK, we examined samples with parallel flow cytometry and immunocytochemistry. MK expression of GP IIb/IIIa (CD41a), GP Ib (CD42b), GP IIIa (CD61), CD45, CD33, and CD11b, and their light scatter properties were evaluated. Fresh samples of low density mononuclear cells (MNC) or purified CD34+ cells contained 10-45% of platelet-coated cells. Platelet-coated cells decreased dramatically after several days of incubation in a serum-free medium supplemented with stem cell factor, IL-3, IL-6, and/or GM-CSF. Between d 9-12, flow cytometry detected a distinct CD41a+ MK population, 8.3 +/- 1.3% in BM CD34 cell cultures (n = 7) and 13.1 +/- 2.1% in PB CD34 cell cultures (n = 14), comparable to immunocytochemistry data (7.8 +/- 1.9% and 16.4 +/- 2.6%, respectively). CD41a stained a higher proportion of MK than CD42b or CD61, while CD42b+ or CD61+ cells contained more morphologically mature MK than CD41a+ cells in cultures containing aplastic serum. When fluorescence emission of CD41a was plotted against forward-light scatter (FSC), subpopulations of small and large MK were observed. Such subpopulations overlapped in CD41a intensity and side-light scatter (SSC) property. Most MK co-expressed CD45 (98.8% positive) but not CD33 (80.7% negative) or CD11b (88.9% negative). Our data indicate that flow cytometry can be used effectively to identify MK. However, caution should be taken with samples containing adherent platelets.

Adult↗
PubMed1996

Selection and expansion of peripheral blood CD34+ cells in autologous stem cell transplantation for breast cancer.

Cytopenia after high-dose chemotherapy and autologous stem cell reinfusion is a major cause of morbidity. Ex vivo cultured expansion and differentiation of CD34+ peripheral blood progenitor cells (PBPC) to neutrophil precursors may shorten the neutropenic period further. We explored the use of these ex vivo cultured PBPCs in nine patients with metastatic breast cancer. All underwent PBPC mobilization with cyclophosphamide, VP-16, and G-CSF. Subsequently, they underwent four to five apheresis procedures. One apheresis product from each patient was prepared using the Isolex 300 Magnetic Cell Separation System (Baxter Immunotherapy, Irvine, CA) to obtain CD34+ cells. These cells were then cultured in gas permeable bags containing serum-free X-VIVO 10 (BioWhittaker, Walkersville, MD) medium supplemented with 1% human serum albumin and 100 ng/mL PIXY321. At day 12 of culture the mean fold expansion was 26x with a range of 6 to 64x. One patient's cells did not expand because of a technical difficulty. The final cell product contained an average of 29.3% CD15+ neutrophil precursors with a range of 18.5% to 48.1%. The patients underwent high-dose chemotherapy with cyclophosphamide, carboplatin, and thiotepa. On day 0, the cryopreserved PBPCs were reinfused and on day +1 the 12-day cultured cells were washed, resuspended, and reinfused into eight of nine patients. One patient was not infused with cultured cells. The mean number of cultured cells reinfused was 44.6 x 10(6) cells/kg with a range of 0.8 to 156.6 x 10(6) cells/kg. No toxicity was observed after reinfusion. The eight patients have recovered absolute neutrophil counts > 500/microL on a median of 8 days (range 8 to 10 days); the median platelet transfusion independence occurred on day 10 (range 8 to 12 days) and platelet counts > 50,000/microL were achieved by day 12 (range 9 to 14) for the seven patients whose platelet counts could be determined. Expanded CD34+ selected PBPC can be obtained and safely reinfused into patients.

Adult↗
PubMed1996

Pancreatic cancer: the potential clinical relevance of alterations in growth factors and their receptors.

Molecular alterations play a key role in the pathogenesis of gastrointestinal cancers. In the present paper we describe relevant molecular alterations in human pancreatic adenocarcinomas. Overexpression of growth factor receptors (EGF receptor, c-erbB2, c-erbB3, TGF beta receptor I-III), growth factors (EGF, TGF alpha, TGF beta-1-3, aFGF, bFGF), adhesion molecules (ICAM-1, ELAM-1) and gene mutations (p53, K-ras, DCC, APC) are present in a significant number of these tumors. These changes stimulate tumor growth and enhance the metastatic behavior of pancreatic cancer cells and thereby may contribute to shorter postoperative survival following tumor resection.

E-Selectin↗
PubMed1996

Altered expression of transforming growth factor-beta S in chronic renal rejection.

We examined the altered expression of transforming growth factor-beta s in chronic renal rejection in humans, including transforming growth factor beta-1 (TGF-beta 1), TGF-beta 2, TGF-beta 3 and their receptors, transforming growth factor beta receptor type I (T beta R-I) and T beta R-II. Using Northern blot analysis and immunohistochemistry, 10 specimens of chronically rejected and 8 normal kidney samples were analyzed. By Northern blot analysis the expression of mRNA encoding TGF-beta 1, TGF-beta 2, TGF-beta 3 (P < 0.02), T beta R-I and T beta R-II (P < 0.02) was decreased in chronically rejected renal cortex samples, compared to normal controls. Immunohistochemical analysis of the normal renal cortex showed strong immunostaining for TGF-beta 1 and TGF-beta 3, and mild immunostaining for TGF-beta 2 in the proximal and distal tubulointerstitium, but no signal for any of the TGF-beta isoforms in the glomeruli or in the cortical vessels. In sharp contrast, the glomeruli and the cortical vessels of the rejected kidney specimens exhibited strong immunostaining for TGF-beta 1 and TGF-beta 3, whereas the tubules revealed a decrease in immunoreactivity. T beta RI and T beta RII immunostaining showed similar changes as observed with TGF-beta 1 and TGF-beta 3 antibodies. There was a concomitant increase in B-cell accumulation in the glomeruli, while T-cells and macrophages were diffusely abundant in the rejected samples. Since TGF-beta S are potent inducers of extracellular matrix proteins and have been shown to be involved in fibrotic disease, the increase in TGF-beta 1 and TGF-beta 3 immunoreactivity in the glomeruli suggests that there is a redistribution in TGF-beta expression in chronic renal allograft rejection. Together with changes affected by B-cell mediated immunity, the above alterations might contribute to the histopathological changes that occur in this disorder, such as intimal fibrosis, arteriosclerosis and glomerular and tubular sclerosis.

Chronic Disease↗
PubMed1996

Large-scale selection of CD34+ peripheral blood progenitors and expansion of neutrophil precursors for clinical applications.

Hematopoietic recovery after high-dose chemotherapy is characterized by an obligate period of neutropenia of approximately 8-10 days. It is postulated that if a pool of neutrophil precursors and progenitors were expanded in vitro and reinfused, the duration of neutropenia may be substantially shortened by these cells capable of providing mature neutrophils within days of reinfusion. In this study, peripheral blood progenitor cell products were obtained from six normal donors mobilized with rhG-CSF and two patients mobilized with cyclophosphamide and rhG-CSF. CD34+ cells were isolated using the Isolex immunomagnetic bead method. A mean of 8.26 x 10(7) CD34+ cells with a mean purity of 74.5% were seeded at a concentration of 1 x 10(5)/ml into a 12 day stroma-free liquid culture using gas-permeable bags. A serum-free growth medium supplemented with PIXY321 was used. On day 7, there was a mean cellular expansion of fourfold, at which time the cells were resuspended at the initial concentration, yielding a mean culture volume of 3L (1-6 L). On day 12, there was an additional mean fold cellular expansion of 10 x, achieving an overall mean fold expansion of 41 +/- 16. Cellular characterization of the expanded cells revealed predominantly neutrophil precursors by morphology (mean 70.1%) and flow cytometric analysis. A mean of 52.3% of the expanded cells expressed CD15. Immunohistochemical staining revealed a mean of 7.1% CD41a+ megakaryocytic progenitors in the final cultured cell product. Detectable CD34+ cells were maintained only in those cultures initiated with greater than 90% CD34+ cells. Colony-forming units-granulocyte-macrophage (CFU-GM) were maintained in the 12 day culture at a level similar to the preculture number, whereas CFU mixed were depleted in all samples. On day 0, there were few CFU clusters (colonies containing fewer than 50 cells) identified, but by day 12, a mean total of 8.3 x 10(6) CFU clusters were identified. On day 12, the expanded cells were harvested and pooled using the Fenwal CS3000 Plus blood cell separator and resuspended in Plasma-Lyte-A with 1% human serum albumin. The mean harvest recovery of expanded progenitors was 91%, with a mean viability of 86%.

Adult↗
PubMed1996

Report of an outbreak: nursing home architecture and influenza-A attack rates.

OBJECTIVE: To determine factors that might account for a significantly lower attack rate in a newly constructed nursing building during an epidemic of type A influenza. SETTING: A four-building, long-term care facility for veterans and their spouses, with an average daily census of 690. DESIGN: Prospective surveillance with retrospective analysis. PARTICIPANTS: Symptomatic residents submitting to viral culture. MEASUREMENTS: Number of respiratory illnesses and influenza cultures in consenting symptomatic residents. Building characteristics. RESULTS: An influenza A (H3N2) outbreak was culture-confirmed in 68 nursing home residents. Influenza A was isolated in 3/184 (2%) residents in Building A, 31/196 (16%) in Building B, 18/194 (9%) in Building C, and 16/116 (14%) in Building D. Denominators are average daily census during the outbreak. Building A had significantly fewer culture-confirmed cases than the other buildings (P < .001). Fewer residents in Building A, 47% compared with 61% in Buildings B, C, and D, were participants in a formal study of influenza. Eight of 15 respiratory illnesses identified during the outbreak that were not cultured occurred in Building A. These factors could not account for the difference in attack rates. Building A has a unique ventilation system, more square feet of public space per resident, and does not contain office space that serves the entire four-building facility. CONCLUSION: Our retrospective observation suggests that architectural design may influence the attack rate of influenza A in nursing homes.

Disease Outbreaks↗
PubMed1996

Hyperlipaemia intensifies the course of acute oedematous and acute necrotising pancreatitis in the rat.

BACKGROUND: Serum triglyceride concentrations higher than 10 to 20 mmol/l are probably a risk factor for developing acute pancreatitis in humans. AIMS: To therefore analyse the influence of hyperlipaemia on the course of acute oedematous and acute necrotising pancreatitis in rats. SUBJECTS: Male Wistar rats were used in all experiments. METHODS: Six different groups of animals were used: two groups without pancreatitis (controls), two with acute oedematous pancreatitis, and two with acute necrotising pancreatitis. One group from each pair was treated with Triton WR 1339, which induces endogenous hyperlipaemia. Blood samples were taken from all subjects to measure triglyceride, cholesterol, amylase, and lipase. Pancreatic tissue samples were taken and the degree of pancreatic damage was judged microscopically. RESULTS: In the control groups no significant changes occurred, either in serum enzyme activities or in histology. The hyperlipaemic subgroup of animals with acute oedematous pancreatitis developed significantly higher (p < 0.001) serum amylase activities and a greater degree of histological damage (p < 0.01) than the animals of the non-hyperlipaemic acute oedematous pancreatitis group. In the animals with necrotising pancreatitis, serum lipase activity and the histological degree of pancreatic damage were significantly higher in the hyperlipaemic animals than in the non-hyperlipaemic animals. CONCLUSION: This study shows that hyperlipaemia intensifies the course of acute oedematous and acute necrotising pancreatitis in rats.

Acute Disease↗
PubMed1996

A technique for gastroplasty as a substitute for the esophagus: fundus rotation gastroplasty.

BACKGROUND: A new method of gastroplasty for the intrathoracic esophagus is described that requires resection of a small part of the gastric corpus only. All tributaries of the arterial arcade along the lesser curvature are preserved. RESULTS: The resulting gastric tube has three advantages over conventional techniques: an increase in length of the resulting gastric tube; an increase of blood flow at the tip of the gastric tube, where the anastomosis with the cervical esophagus is performed; and an increase of the gastric reservoir. STUDY DESIGN: Prospective clinical trial. CONCLUSIONS: The new technique described appears to be a safe method to substitute for the intrathoracic esophagus, although oncologic radicality and long-term follow-up results after esophagectomy for carcinoma need to be evaluated.

Adult↗
PubMed1996

[Pancreas transplantation--indication, technique and results].

Pancreas transplantation is the only therapeutic measure currently available to achieve long term normoglycemia and normal HbA1 levels in diabetic patients. A live long immunosuppression with it's side effects is the price payed for that treatment. Like in renal transplantation an alternative treatment is available for potential pancreas transplant recipients so that most transplant centers are willing to perform pancreas transplantation as a combined kidney pancreas transplantation in patients with diabetic nephropathy only. This article reviews indications, technique, results and complications of simultaneous kidney pancreas transplantation and pancreas after kidney transplantation.

Diabetes Mellitus, Type 1↗
PubMed1996

Congenital bile duct cyst: a premalignant lesion of the biliary tract associated with adenocarcinoma--a case report.

The incidence of carcinoma arising in the wall of a congenital bile duct cyst is high and there is no doubt that these lesions represent a precancerous state of the biliary tract. In almost all cases congenital bile duct cysts are related to anomalous arrangements of the pancreaticobiliary duct system which seems to play a crucial role in the development of cystic bile ducts and biliary carcinogenesis. Bile stasis together with reflux of pancreatic juice causing longstanding inflammation and activation of bile acids might be the factors in carcinogenesis of the exposed bile duct epithelium in the cystic wall. In the case of primary or secondary extrahepatic bile duct cysts, primary excision is mandatory because of the high risk to develop biliary cancer with even nowadays poor prognosis despite advantages in biliary surgery during the last years. We report a case of a young woman in which bile duct cancer was found arising in the wall of a congenital bile duct cyst. Despite radical surgery the outcome was poor proving the high malignant potential of bile duct cancer. The question of possible tumor seeding in hepatobiliary surgery is discussed as a way of inducing hepatobiliary metastatic tumors.

Adenocarcinoma↗
PubMed1996

[Treatment with tissue plasminogen activator (tPA) in risk patients with fibrin reactions after cataract operations].

The postoperative course after cataract surgery can be complicated by the formation of severe fibrinous membranes, especially in cases with previous goniotrepanation, after syn echiolysis, iridotomy or iris suturing, and in patients with diabetes or uveitis. This study retrospectively analyzes the efficacy of intraocular tissue plasminogen activator (tPA) for fibrinolysis in these conditions commonly considered as contraindications to tPA therapy. When antiinflammatory therapy was unsuccessful in lysing fibrinous membranes, 10 micrograms of tPA (Actilyse) was injected into the anterior chamber following the first postoperative day (n = 15). In addition, topical corticosteroids and cycloplegics were given postoperatively. Lysis of the fibrinous membranes was achieved in all patients. However, in three cases lysis was incomplete or recurred. Complications of intraocular tPA therapy consisted of mild hyphema (n = 1) and transient dysfunction of the corneal endothelial cells (n = 2). In conclusion, the results suggest intraocular low-dose tPA as an effective approach for the treatment of severe fibrinous membranes after cataract surgery even in high-risk patients.

Adolescent↗
PubMed1996

[Inhibition of secretion in pancreas surgery reduces postoperative complication rate: a meta analysis of 4 multicenter studies].

We report on a meta-analysis of four randomized, placebo-controlled, double-blind multicenter trials evaluating the role of perioperative octreotide treatment in the prevention of postoperative complications following elective pancreatic surgery. From a total of 963 patients (483 placebo, 480 octreotide), the postoperative complication rate (329 placebo, 206 octreotide) and the number of patients with postoperative complications (placebo 38%, octreotide 22%) were significantly higher in the placebo groups compared with the octreotide groups. Postoperative morality was comparable between the placebo (3.9%) and the octreotide (3.5%) groups. These data indicate that perioperative application of octreotide can prevent postoperative complications following pancreatic surgery.

Double-Blind Method↗
PubMed1995

Treatment of lymphocele in renal transplant recipients by laparoscopic fenestration after transcutaneous staining.

Lymphocele is a rare cause of impairment of graft function after renal transplantation. Treatment ranges from external drainage to laparoscopic internal marsupialization. A therapeutic approach to the treatment of symptomatic lymphocele is described, which employs external drainage, if necessary followed by methylene blue staining and laparoscopic internal drainage, should conservative treatment fail. Five patients developed post-transplant lymphocele of varying size and were treated according to this protocol. Identification of the blue lymphocele at laparoscopy was straightforward and complete marsupialization was performed. After a mean follow-up of 8.4 months all patients are free from symptoms and have well functioning grafts.

Algorithms↗