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Biomedical subjects

G Schwab

Publications and source records attributed to G Schwab.

At least 19 recordsLinked to original sources
PubMed1999

Spontaneous apoptosis and the expression of p53 and Bcl-2 family proteins in locally advanced head and neck cancer.

BACKGROUND: Apoptotic cell death plays a key role in the pathogenesis, aggressiveness, and therapy responsiveness of cancer. The suicidal machinery of apoptosis is genetically controlled. Proteins of the Bcl-2 family as well as p53 are important regulators of apoptosis. OBJECTIVE: To assess the rate of spontaneous apoptosis and the expression of p53 and Bcl-2 family proteins in locally advanced squamous cell carcinomas of the head and neck. DESIGN: Twenty-six patients with locally advanced squamous cell carcinoma of the head and neck were included in the study. The expression of p53, Bcl-2, Mcl-1, Bax, and Bak was assessed by immunohistochemical analysis. The terminal deoxytransferase-mediated deoxyuridine nick end-labeling assay was used to quantify apoptosis by flow cytometry. RESULTS: Tumor cells containing immunostaining for the antiapoptotic proteins Bcl-2 and Mcl-1 were present in 4 (15%) and 24 (92%) of the cases evaluated, respectively, whereas immunopositivity for the proapoptotic proteins Bax and Bak was found in 9 (35%) and 24 (92%) of the samples. Immunoreactivity to p53 was detected in 20 (77%) of the samples. There was a positive correlation between the expression of Bcl-2 and Bax and between Mcl-1 and Bak. A low fraction of apoptotic cells (<2.5%) in the pretreatment tumor samples was significantly correlated with increased 2-year survival in these patients. CONCLUSIONS: Our results establish the frequent expression of the Bcl-2 family proteins Bcl-2, Mcl-1, Bax, and Bak in locally advanced head and neck cancer. In addition, this study suggests that the apoptotic fraction in pretreatment tumor samples might be of prognostic importance for the outcome in these patients.

Adult↗
PubMed1999

A new form of Filgrastim with sustained duration in vivo and enhanced ability to mobilize PBPC in both mice and humans.

Granulocyte colony-stimulating factor (G-CSF) has proven effective in the prophylaxis of chemotherapy-induced neutropenia and as a mobilizer of peripheral blood progenitor cells. The longevity of G-CSF action is limited by its removal from the body by two mechanisms. The first is thought to be mediated via receptors (receptor mediated clearance [RMC]) predominantly on neutrophils, the second process is likely the result of renal clearance. With the intention of developing a novel form of Filgrastim (r-met HuG-CSF) with a sustained duration of action in vivo, a new derivative named SD/01 has been made by association of Filgrastim with poly(ethylene glycol). The desired properties of this new agent would include a prolonged duration of action sufficient to cover a complete single course of chemotherapy. SD/01 is shown here to sustain significantly elevated neutrophil counts in hematopoietically normal mice for 5 days. In neutropenic mice effects were noted for at least 9 days, accompanying a significant reduction in the duration of chemotherapy induced neutropenia. Normal human volunteers showed higher than baseline ANC for around 9 to 10 days after a single injection of SD/01. Data from these normal volunteers also indicate that mobilization of CD34+ cells and progenitors may occur in a more timely manner and to around the same absolute numbers as with repeated daily injections of unmodified Filgrastim. These data indicate that SD/01 represents an efficacious novel form of Filgrastim with actions sustained for between one and two weeks from a single injection.

Animals↗
PubMed1999

Sequential cycles of high-dose chemotherapy with dose escalation of carboplatin with or without paclitaxel supported by G-CSF mobilized peripheral blood progenitor cells: a phase I/II study in advanced ovarian cancer.

To assess high-dose carboplatin chemotherapy with or without paclitaxel with filgrastim mobilized peripheral blood progenitor cell (PBPC) support in a phase I/II study, a total of 21 patients with mostly chemonaive disease received four cycles of high-dose chemotherapy. Cycle 1 (cyclophosphamide, 6 g/m2) was followed by two cycles of carboplatin (1600 mg/m2 or 1800 mg/m2). Cycle 4 consisted of carboplatin (1600 mg/m2), etoposide (1600 mg/m2), and melphalan (140 mg/m2). Further chemotherapy intensification was achieved by adding paclitaxel (175 mg/m2) to all cycles with a fixed carboplatin dose (1600 mg/m2). Ototoxicity was dose-limiting for escalation of sequential cycles of carboplatin. Grade 2 and grade 3 ototoxicity, hearing loss not requiring a hearing aid, or hearing loss correctable with a hearing aid, was observed with carboplatin at 1800 mg/m2. The maximum tolerated dose (MTD) of sequential carboplatin, therefore, was identified in this study as 1600 mg/m2. After cycles 1, 2, 3 and 4 the median duration of leukopenia (<1.0x10(9)/l) was 7, 4, 4 and 6 days. Severe grade 3 and 4 infections were seen in only 7% of cycles. Of the 21 patients evaluable for disease response, 57% had complete remissions and 43% experienced partial remissions resulting in an overall response rate of 100%. The median progression-free survival is 25 (15-36) months, the median overall survival 36.5 (15-38) months. Most patients were suboptimally debulked or had bulky residual disease at the start of chemotherapy. Sequential high-dose chemotherapy to a maximum dose of 1600 mg/m2 carboplatin is effective and feasible. A randomized, prospective trial comparing sequential high-dose chemotherapy with optimal standard chemotherapy is now warranted.

Adult↗
PubMed1998

Allogeneic bone marrow transplantation vs filgrastim-mobilised peripheral blood progenitor cell transplantation in patients with early leukaemia: first results of a randomised multicentre trial of the European Group for Blood and Marrow Transplantation.

In a multicentre trial involving 20 transplant centres from 10 countries haematopoietic stem cells were obtained either from the bone marrow of 33 sibling donors or from the peripheral blood of 33 such donors after administration of filgrastim (10 microg/kg/day). The haematopoietic stem cells were infused into their HLA-identical recipients suffering from acute leukaemias in remission or chronic myeloid leukaemia in chronic phase. PBPC donors tolerated filgrastim administration and leukapheresis well with the most frequent side-effects being musculoskeletal pain, headache, and mild increases of LDH, AP, Gamma-GT or SGPT. Pain and haematoma at the harvest site and mild anaemia were the most frequent complaints of BM donors. Severe or life-threatening complications were not seen with any type of harvest procedure. Time to platelet recovery greater than 20 x 10(9)/l was 15 days (95% confidence interval (CI) 13-16 days) in the PBPCT group and 19 days (CI 16-25) in the BMT group. Time to neutrophil recovery greater than 0.5 x 10(9)/l was 14 days (CI 12-15 days) in the PBPCT group as compared to 15 days (CI 15-16 days) in the BMT group. The numbers of platelet transfusions administered to PBPCT and BMT patients were 12 (range: 1-28) and 10 (range: 3-39), respectively. Sixteen patients (48%) transplanted with bone marrow and 18 patients (54%) transplanted with PBPC developed acute GVHD of grades II-IV; acute GVHD of grades III or IV developed in six (18%) and seven (21%) patients, respectively. Kaplan-Meier plots for transplant-related mortality until day 100 and leukaemia-free survival at a median of 400 days after BMT or PBPCT showed no significant differences. Administration of filgrastim and leukapheresis in normal donors were feasible and well tolerated. The number of days with restricted activity and of nights spent in hospital was lower in donors of PBPC. Transplantation of PBPC to HLA-identical siblings with early leukaemia resulted in earlier platelet engraftment. The incidence of moderate to severe acute GVHD, transplant-related mortality, and leukaemia-free survival did not show striking differences. Further investigation of allogeneic PBPCT as a substitute for allogeneic BMT is warranted.

Adolescent↗
PubMed1998

Dieulafoy's disease of the large and small bowel.

The Dieulafoy lesion is a rare cause of severe gastrointestinal hemorrhage. The lesion is usually located in the stomach, although it may occur anywhere in the gastrointestinal tract. We describe four patients with extragastric Dieulafoy's disease, in the duodenum (one), the proximal jejunum (two), and the left hemicolon (one). Diagnosis was made by endoscopy in all four and confirmed by histology in three. The pathology of the Dieulafoy lesion is essentially the same throughout the gastrointestinal tract. Endoscopic treatment by sclerotherapy combined with electrocoagulation was successful in the duodenal and colonic Dieulafoy lesions, but not in the jejunal lesions.

Adult↗
PubMed1997

Respiratory symptoms in patients with gastroesophageal reflux disease following medical therapy and following antireflux surgery.

BACKGROUND: It is not known whether antireflux surgery is more effective than medical therapy to control respiratory symptoms (RS) in gastroesophageal reflux disease (GERD). METHODS: In 21 GERD patients with RS, reflux was assessed by endoscopy, manometry, and pH monitoring. Patients had proton pump inhibitor therapy and cisapride for 6 months. After GERD relapsed following withdrawal of medical therapy, 7 patients with normal esophageal peristalsis had a laparoscopic Nissen fundoplication and 14 with impaired peristalsis a Toupet fundoplication. Respiratory symptoms were scored prior to treatment, at 6 months following medical therapy, and at 6 months after surgery. RESULTS: Heartburn and esophagitis were effectively treated by medical and surgical therapy. Only surgery improved regurgitation. Respiratory symptoms improved in 18 patients (85.7%) following surgery and in only 3 patients (14.3%) following medical therapy (P <0.05). Esophageal peristalsis improved following the Toupet fundoplication. CONCLUSION: Medical therapy fails to control reflux since it does not inhibit regurgitation. Surgery controls reflux and improves esophageal peristalsis, which contributes to its superiority over medical therapy in the treatment of RS associated with GERD.

Adult↗
PubMed1996

Mechanism of apoptosis suppression by phorbol ester in IL-6-starved murine plasmacytomas: role of PKC modulation and cell cycle.

We show here that the mode of cell death in IL-6-starved T1165 and T1198 plasmacytoma cell lines is apoptosis, and that it can be suppressed by phorbol ester (PMA) treatment in a protein kinase C (PKC)-mediated process that involves alpha and/or delta isozymes. PMA-induced PKC activation, but not the depletion that follows it, participates in the suppression of apoptosis. Extended PKC activation is necessary but not sufficient for the apoptosis suppression. In addition, the cells must be in a "competent" state, which appears not to be determined by PKC. We observed two points of "competence" during the time between withdrawal of IL-6 and the start of massive cell death: one, immediately after withdrawal, and another, just before onset of apoptosis, at the time corresponding to maximal accumulation of cells in a G0/G1 block imposed by IL-6 withdrawal. Treatment with PMA and other PKC activators resulted in a shift of the cell population to S phase, lifting the G0/G1 block. We propose a model in which cells are rescued in a certain stage of the G1 phase of cell cycle. Death suppression occurs when a transient PMA-induced PKC activation occurs when a significant number of cells are in this part of G1, allowing them to pass the restriction point safely without initiating the cell death program.

Alkaloids↗
PubMed1996

A randomized phase-III study of the efficacy of granulocyte colony-stimulating factor in children with high-risk acute lymphoblastic leukemia. Berlin-Frankfurt-Münster Study Group.

Overall chemotherapeutic treatment results in pediatric acute lymphoblastic leukemia (ALL) are good, with event-free survival (EFS) rates over 70%. However, for a subset of patients characterized by high-risk (HR) features the outcome is less favorable, with EFS rates below 50%. Intensification of chemotherapy may improve the outcome for those patients, but increased toxicity, particularly myelosuppression, limits the escalation of dose intensity. Recombinant methionyl human granulocyte colony-stimulating factor (r-metHuG-CSF) is known to reduce myelosuppression after cancer chemotherapy in adults. The objective of this study was to examine the effect of r-metHuG-CSF on myelosuppression in HR pediatric ALL patients and on the overall response rate to chemotherapy. Patients with HR pediatric ALL were randomized to receive nine alternating cycles of chemotherapy according to the German ALL-Berlin-Frankfurt-Münster 90 protocol either alone or followed by r-metHuG-CSF administered prophylactically at a dose of 5 microg/kg/d subcutaneously. In both groups, the planned interval between chemotherapy courses was a minimum of 21 days. We report here interim results of 34 patients. The incidence of febrile neutropenia (absolute neutrophil count <0.5 x 10(9)/L and oral temperature > or = 38.5 degrees C) was 17% in children receiving r-metHuG-CSF, as compared with 40% in the control group (P = .007). In addition, the median total duration of febrile neutropenia was reduced from 20.3 to 6.2 days per patient (P = .02). Culture-confirmed infections occurred less frequently in the r-metHuG-CSF group (8% v 15%; P = .04), and the total duration of intravenous antibiotic use was significantly reduced from 32.2 days to 18.2 days per patient (P = .02). A tighter adherence to the planned treatment schedule was also facilitated by r-metHuG-CSF (P = .007). With a median follow-up of 3.3 years, the estimated EFS of 4 years is 41% +/- 12%. In conclusion, r-metHuG-CSF administered prophylactically in the interval between chemotherapy courses significantly reduced febrile neutropenia, culture-confirmed infections, and duration of intravenous antibiotic administration and allowed for tighter adherence to the treatment schedule.

Adolescent↗
PubMed1996

Helicobacter pylori infection and blood group antigens: lack of clinical association.

OBJECTIVES: Blood group antigens traditionally have been associated with a risk of developing peptic ulcer and gastric cancer. Helicobacter pylori is a bacterium associated with chronic active gastritis and ulcer disease, and its attachment to gastric mucosa was recently shown in vitro to be mediated by blood group Lewisb and H antigens. This study was designed to test the clinical relevance of this laboratory observation in patients undergoing endoscopy and gastric biopsy. METHODS: Blood group phenotypes and gastric biopsies for H. pylori and histology were determined and correlated in 384 patients undergoing upper endoscopy. Blood from healthy blood donors was tested for the same blood group antigens and used as a control group. RESULTS: The distribution of blood groups ABO, Lewis, Rhesus, and MN was similar among the patients undergoing endoscopy and a control group of 2369 healthy blood donors from the same geographic area. There was no correlation between H. pylori infection or the H. pylori-associated diseases, peptic ulcer or chronic active gastritis, with any blood group phenotype, including Lewisb, blood group O, or both. CONCLUSION: No in vivo correlation between H. pylori infection or disease and Lewisb or H antigen could be demonstrated. Moreover, patients with H. pylori infection and disease have a distribution of blood group antigens similar to a control population.

Biopsy↗
PubMed1995

Rational design of point mutation-selective antisense DNA targeted to codon 12 of Ha-ras mRNA in human cells.

Antisense oligodeoxynucleotides targeted to Ha-ras mRNA have been designed to discriminate between the codon 12-mutated oncogene and the normal proto-oncogene. An in vitro assay using two different sources of RNase H (rabbit reticulocyte lysates and nuclear extract from HeLa cells) was used to characterize oligonucleotide binding to normal and mutated Ha-ras mRNA. Short oligonucleotides (12- or 13mers) centered on the mutation had a very high discriminatory efficiency. Longer oligonucleotides (16mers) did not discriminate efficiently between the mutated and the normal mRNA. We have tested the efficacy of dodecanucleotides to induce RNase H cleavage of the full-length mRNA, moving the target sequence from the loop to the stem region which is formed in the vicinity of mutated codon 12. The most selective oligonucleotides were centered on the mutation which is located near the junction between the loop and stem regions even though they were less efficient at inducing RNase H cleavage than those targeted to the loop region. The 12mer antisense oligonucleotide with the highest discriminatory power was selected for cell culture studies. This oligonucleotide inhibited the proliferation of a human cell line which had been transformed with the mutated Ha-ras gene (HBL100ras1) but had no effect on the parental cell line which was transfected with the vector DNA (HBL 100neo) and expressed only the normal Ha-ras gene. Growth inhibition of HBL100ras1 cells was associated with specific ablation of targeted Ha-ras mRNA as shown by RT-PCR. These results show that 'in vitro' evaluation using an RNase H assay allowed us to select an antisense oligonucleotide which elicited a selectivity towards point-mutated Ha-ras mRNA when added at 10 microM concentration to the culture medium of cells expressing wild type and mutated Ha-ras mRNA.

Base Sequence↗
PubMed1994

Antisense oligonucleotides adsorbed to polyalkylcyanoacrylate nanoparticles specifically inhibit mutated Ha-ras-mediated cell proliferation and tumorigenicity in nude mice.

Ras oncogenes owe their transforming properties to single point mutations in the sequence coding for the active site of the p21 protein. These mutations lead to changes in cellular proliferation and induce tumorigenic properties. Point mutations represent a well-defined target for antisense oligonucleotides that can specifically suppress the translation of the targeted mutant mRNA. We show that the stability and cellular disponibility of antisense oligonucleotides can be markedly improved by adsorption to polyalkylcyanoacrylate nanoparticles. Nanoparticle-adsorbed antisense oligonucleotides directed to a point mutation (G-->U) in codon 12 of the Ha-ras mRNA selectively inhibited the proliferation of cells expressing the point-mutated Ha-ras gene at a concentration 100 times lower than free oligonucleotides. In addition they markedly inhibited Ha-ras-dependent tumor growth in nude mice after subcutaneous injection. These experiments show that inhibition of ras oncogenes by antisense oligonucleotides can block tumor development even though ras oncogenic activation might be an early event in tumor progression.

Adsorption↗
PubMed1994

Subcutaneous abscess due to gallstones lost during laparoscopic cholecystectomy.

No complications caused by gallstones lost during laparoscopic cholecystectomy have yet been described in the literature. In one animal study in rats, it has been shown that pigment calculi, but not cholesterol stones, lead to severe local inflammation of the abdominal cavity. We present a case of a chronic subcutaneous and subfascial abscess in the lower abdomen, which included multiple pigment calculi, six months after laparoscopic cholecystectomy. During the procedure, multiple small pigment calculi had been lost into the free abdominal cavity.

Abdomen↗
PubMed1994

An approach for new anticancer drugs: oncogene-targeted antisense DNA.

BACKGROUND: Ras oncogenes owe their transforming properties to single point mutations in the sequence coding for the catalytic part of the p21 protein. These mutations lead to changes in cellular proliferation and tumorigenic properties. Point mutations represent a defined target for antisense oligonucleotides which specifically suppress translation of the targeted mRNA. However, the use of oligonucleotides in vivo has, until now, been limited by their instability in serum. NEW TECHNIQUES: Different strategies have been developed to protect the oligonucleotides and increase their transport into the target cell. Linking intercalating agents, hydrophobic groups or polycations to oligonucleotides or encapsulating them in liposomes resulted in a higher resistance to exonucleases and increased oligonucleotide penetration into cells. The stability and cellular uptake of antisense oligonucleotides can also be improved by associating them with polyalkylcyanoacrylate nanoparticles. The polymeric nature renders these small particles more stable than liposomes in biological fluids and during storage. METHOD: Antisense oligonucleotides directed to the point mutation (G to T) in codon 12 of the Ha-ras mRNA were adsorbed to nanoparticles in the presence of hydrophobic cations. RESULTS: These stabilized oligonucleotides selectively inhibited the proliferation of cells expressing this point mutation and partially reversed their tumorigenicity in nude mice.

Antineoplastic Agents↗
PubMed1994

Traumatic bilhemia.

BACKGROUND: Retrospective analysis was done of three cases with severe liver trauma and excessive serum bilirubin levels caused by a traumatic biliovenous fistula. The literature is reviewed. METHODS: Diagnostic measures included laboratory findings, computed tomography, ultrasonography, and endoscopic retrograde cholangiopancreatography (ERCP). RESULTS: The biliovenous fistula was detected by ERCP in two cases. In one case a left hemihepatectomy was carried out, and the patient was cured. The other patient received drainage of a huge necrotic cavity in the center of the liver. Ten months later the patient underwent reoperation, and left hepatic resection was performed. The patient died of liver function failure on postoperative day 7. In the third case the fistula subsided spontaneously. CONCLUSIONS: An excessively high serum level of direct bilirubin and only moderately elevated liver enzymes indicate bilhemia in trauma patients. ERCP is most reliable in localizing the fistula; computed tomography/ultrasonography are valuable in detecting the extension and localization of the parenchymal destruction. Conservative therapy is justified if the patient is in good condition or if the localization of the fistula is unclear. Spontaneous closure of the fistula may occur. Surgical treatment options are partial liver resection and suture of the fistula and T-tube drainage of the common bile duct and drainage of the rupture site.

Adolescent↗
PubMed1992

Benzoquinonoid ansamycins possess selective tumoricidal activity unrelated to src kinase inhibition.

The benzoquinonoid ansamycin antibiotics herbimycin A and geldanamycin have been shown to reverse the oncogenic phenotype of pp60v-src transformed cells as well as induce differentiation in a number of in vitro model systems, reportedly due to their inhibition of src family protein tyrosine kinases. We now report that these agents are potent cytotoxins in vitro against a panel of highly malignant human tumor cell lines possessing primitive neural features. Proliferation and/or survival of fibroblasts, primary neuronal cultures, and several leukemia cell lines are unaffected at concentrations resulting in greater than 99% cell loss in sensitive lines. The tumorigenicity in nude mice of sensitive cell lines can also be markedly reduced by either systemic or topical administration of these agents without apparent toxicity to the whole animal. The cytocidal action of these ansamycins is initiated very rapidly, is irreversible, and is clearly distinct from the delayed inhibition of src family kinases that has been reported previously. Due to their potency, relative selectivity, and novel mechanism(s) of action, these drugs could prove clinically useful in the therapy of a number of human cancers of neural derivation.

3T3 Cells↗