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Biomedical subjects

G Schroeder

Publications and source records attributed to G Schroeder.

At least 19 recordsLinked to original sources
PubMed2006

Critical steps in fluoroquinolones and carbapenems prescriptions: results from a prospective clinical audit.

Antibiotic misuse is associated with emergence of resistance and high expenditures. Fluoroquinolones (FQ) and carbapenems (CP) are drugs with considerable potential of resistance development and its disseminated use is a concern. We undertook a prospective clinical audit to evaluate prescriptions of FQ and CP in a multistep process. Each prescription was unfolded in the following steps: indication for antimicrobial therapy; adequacy of initial prescription, dosage and route; previous cultures; and parenteral-oral transition. There was no antibiotics indication in 8.9% of FQ and 1.5% of CP group (p = 0.07). In CP 25.8% of initial schemes were inappropriate (21% in FQ). Lack of switch to oral therapy comprised 25% of monthly costs of FQ. Inadequacy in initial choice accounted for 13.6% of CP expenses. We concluded that, in spite of infection control restrictive policies, inappropriateness of antibiotic usage is worrisome. Clinical audit in a multistep approach may identify possible flaws in this process.

Anti-Bacterial Agents↗
PubMed2005

Microstructural insight into pedestrian pelvic fracture as assessed by high-resolution computed tomography.

Pelvic and femoral neck bone surface strains were recorded in five full-body human cadaver vehicle-pedestrian impacts. Impacts were performed at 40 km/h using automotive front ends constructed to represent those used in previously reported finite element simulations. While experimental kinematics and bone strains closely matched model predictions, observed pelvic fractures did not consistently agree with the model, and could not be solely explained by vehicle geometry. In an attempt to reconcile injury outcome with factors apart from vehicle design, a proxy measure of subject skeletal health was assessed by high-resolution quantitative computed tomography (HRqCT) of the femoral neck. The incidence of hip/pelvis fracture was found to be consistent with low volumetric bone mineral density and low trabecular bone density. This finding lends quantitative support to the notion that healthy trabecular architecture is crucial in withstanding non-physiological impact loads. Furthermore, it is recommended that injury criteria used to assess vehicle safety with regard to pedestrians consider the increased susceptibility of elderly victims to pelvic fracture.

Accidents, Traffic↗
PubMed2003

In vitro antiproliferative activity of the farnesyltransferase inhibitor R115777 in hematopoietic progenitors from patients with myelofibrosis with myeloid metaplasia.

R115777 is an orally bioavailable farnesyltransferase inhibitor (FTI) that has displayed encouraging activity in patients with acute myeloid leukemia. To determine whether R115777 might exert similar activity in myelofibrosis with myeloid metaplasia (MMM), we evaluated its effects on circulating myeloid progenitor cells from patients with MMM (n=25) using in vitro colony-forming assays. The median R115777 concentrations that inhibited colony formation by 50% were 34 and 2.7 nM for myeloid and megakaryocytic colonies from MMM patients, respectively. Progenitors from normal controls and patients with other myeloproliferative disorders demonstrated similar sensitivity. Since the ras polypeptides are one putative target of FTIs, the potential role of ras effectors was examined by incubating parallel progenitor assays with the phosphatidyl-inositol-3 (PI-3) kinase inhibitor LY294002 and the mitogen-activated protein kinase 1 inhibitor PD98059. MMM progenitor colonies (n=7) were highly sensitive to LY294002 but not to PD98059, implying that the PI-3 kinase pathway may be critical for survival and proliferation of these cells. In addition to indicating that MMM progenitors are sensitive to clinically achievable R115777 concentrations in vitro, these results provide a potential explanation for the thrombocytopenia observed with R115777 during the treatment of other hematologic malignancies.

Adult↗
PubMed2002

Plantar impact causing midfoot fractures result in higher forces in Chopart's joint than in the ankle joint.

PURPOSE: Force effect (impact, extent of foot compartment deformation) and result (fracture pattern) for midfoot fractures in car occupants is known. An analysis of the processes in the foot was intended to improve car safety. MATERIALS AND METHODS: Eleven fresh, unfrozen, unpreserved intact human cadavers (age: 36.8 (16-61) years, gender: male, race: Caucasian) were studied 24-72 h after death. In 3 cadavers (5 feet) the experimental design was established: entire cadaver fixed on a special tray in supine position, pendulum with bar impactor hitting the foot plantar to Lisfranc's joint. A custom-made pressure sensor was inserted in the ankle (A), talonavicular (TN) and calcaneocuboid (CC) joints (resolution: 1 cm2, sampling rate: 500/s). RESULTS: Sixteen feet were measured: midfoot fractures were induced in 11 feet. The maximum pressure amounted to 1.22-2.55 MPa (2.04+/-0.412) at 0.005 0.195 s (0.067+/-0.059) after impact. The maximum pressure occurred in 8 (50%) cases in the ankle, in 7 (44%) of the TN and 1 (6%) of the CC joints. A comparison of the first 200 pressure samples after impact of all sensor fields resulted in higher forces in Chopart's joint than in the ankle (t-test: p < 0.001). These force differences were higher in cases with midfoot fractures (mixed model analysis of variance: p = 0.003). CONCLUSION: Due to considerable forces in Chopart's joint we recommend a modification of the actual crash test dummy lower extremity model with an additional load cell that detects forces in the longitudinal direction of the foot axis.

Adolescent↗
PubMed2002

Possibilities for load reductions using garment leg protectors for motorcyclists -- a technical, medical and biomechanical approach.

This study has considered demands placed on protective clothes for motorcyclists together with observed benefits and limitations for absorbing loads and preventing injuries. In this study, 1933 accidents involving injured motorcyclists, collected by an in-depth investigation team at ARU-MUH, were analysed to find the detailed injury patterns comparing persons with and without protective clothes. The parameters influencing the force reduction are discussed comparing impact speed, elasticity coefficient and thickness of the materials used in special protectors. Additionally, post mortem human tests were carried out to find the effectiveness of such protector devices for load reductions in the lower leg. This study showed that loads, and the subsequent risk of fractures, can be reduced efficiently by foam-plate systems. Benefits were established for using a laminate of hard and soft materials for protection against soft tissue injuries both in the accident analysis and experimental tests.

Accidents, Traffic↗
PubMed2001

Clinical correlates of splenic histopathology and splenic karyotype in myelofibrosis with myeloid metaplasia.

Splenic extramedullary hematopoiesis is an integral component of myelofibrosis with myeloid metaplasia (MMM) and may be classified into 3 distinct histologic patterns of infiltration by myeloid precursors: diffuse, nodular, and a predominance of immature granulocytes. These 3 histologic patterns occurred in 121 (56.8%), 75 (35.2%), and 17 (8%), respectively, of 213 patients with MMM who underwent splenectomy at a single institution. In general, karyotypic findings in splenic tissue (n = 92) were similar to those seen in the bone marrow. The histologic pattern of immature granulocyte predominance, the presence of microscopic splenic infarcts (26 patients), or the detection of an abnormal splenic karyotype (52 patients) was significantly associated with decreased postsplenectomy survival. These adverse features were also associated with characteristics of advanced disease. These observations support the bone marrow origin of the myeloid progenitor pool in the spleen of patients with MMM and suggest a prognostic value for splenic histopathology and karyotype. (Blood. 2001;97:3665-3667)

Bone Marrow Cells↗
PubMed2001

7Li-NMR and FTIR studies of lithium, potassium, rubidium, and cesium complexes with ionophore lasalocid in solution.

Lasalocid metal salts were combined with 1 : 1 lithium and 2:2 potassium, rubidium, and cesium to form complexes. The nature of the lasolocid salt complexes was studied in a solid and chloroform by FTIR spectroscopy in the middle and far IR regions. The process of the complexation of lithium was also studied by (7)Li-NMR. In chloroform a 1 : 1 complex of lasalocid and Li(+) ions was formed. Continuous absorption was observed in the far FTIR spectrum of this complex. It indicated large Li(+) polarizability, which was due to fast fluctuations of the Li(+) ions in the multiminima potentials, in the monomeric structure. In the lasalocid salt with the other monovalent cations (K(+), Rb(+), Cs(+)) 2:2 complexes were formed in which the cations showed cation polarizability, which strongly depended on the mass and the radius of the cations.

Cesium↗
PubMed2001

Amifostine alone and in combination with erythropoietin for the treatment of favorable myelodysplastic syndrome.

Ten anemic patients with favorable myelodysplastic syndrome (MDS) were first treated with two 5-week courses of amifostine alone (each course consisted of 200 mg/m(2) of the drug given intravenously three times a week for 3 weeks), followed by an additional two courses combined with subcutaneous erythropoietin (EPO) (150 U/kg, three times a week for 8 weeks). The study patients either had previously failed to respond to treatment with EPO or had pretreatment serum EPO levels of more than 100 mU/ml. None of the patients experienced a complete or partial response in anemia or other cytopenias. We conclude that amifostine alone or in combination with EPO has limited therapeutic activity in MDS.

Aged↗
PubMed2001

Cytogenetic findings and their clinical relevance in myelofibrosis with myeloid metaplasia.

The prognostic significance of bone marrow cytogenetic lesions in myelofibrosis with myeloid metaplasia (MMM) was investigated in a retrospective series of 165 patients. An abnormal karyotype was demonstrated in 57% of patients. At diagnosis (n = 92), 48% of the patients had detectable cytogenetic abnormalities, and clonal evolution was frequently demonstrated in sequential studies. More than 90% of the anomalies were represented by 20q-, 13q-, +8, +9, 12p-, and abnormalities of chromosomes 1 and 7. Of these, 20q-, 13q- and +8 were the most frequent sole abnormalities, each occurring in 15-25% of the abnormal cases. Trisomy 9 and abnormalities of chromosomes 1 and 7 were equally prevalent but were usually associated with additional cytogenetic lesions. Chromosome 5 abnormalities were infrequent but were over-represented in the group of patients exposed to genotoxic therapy. In a multivariate analysis that incorporated other clinical and laboratory variables, the presence of an abnormal karyotype did not carry an adverse prognosis. Instead, +8, 12p-, advanced age and anaemia were independent prognostic determinants of inferior survival. In particular, survival was not adversely affected by the presence of either 20q- or 13q-.

Adult↗
PubMed2000

Evaluation and clinical correlations of bone marrow angiogenesis in myelofibrosis with myeloid metaplasia.

Recent observations have underscored the biologic relevance of intratumoral angiogenesis and its potential impact on prognosis. Increased bone marrow angiogenesis has been demonstrated in a variety of hematologic disorders, including multiple myeloma. The extent and prognostic significance of bone marrow angiogenesis in 114 patients with myelofibrosis with myeloid metaplasia (MMM) was investigated. A control group of 44 patients without bone marrow disease, 15 patients with polycythemia vera, and 17 patients with essential thrombocythemia was also studied. Bone marrow microvessel density was assessed by a semiquantitative method, visual microvessel grading, and 2 separate quantitative methods, visual count and computerized image analysis. Angiogenesis estimation by all 3 methods was highly comparable. On visual microvessel grading, a grade 3 or 4 increase in bone marrow angiogenesis was demonstrated in 70% of patients with MMM, 33% of patients with polycythemia vera, 12% of patients with essential thrombocythemia, and 0% of normal controls. In a multivariate analysis, increased angiogenesis in MMM correlated significantly with increased spleen size and was found to be a significant and independent risk factor for overall survival. Increases in marrow angiogenesis correlated with hypercellularity and megakaryocyte clumping. In contrast, these 2 features were inversely proportional to reticulin fibrosis, whereas increases in marrow angiogenesis were independent of reticulin fibrosis. These preliminary findings suggest that neo-angiogenesis is an integral component of the bone marrow stromal reaction in MMM and may provide useful prognostic information and a rationale for the therapeutic investigation of anti-angiogenic agents.

Adult↗
PubMed2000

Splenectomy in myelofibrosis with myeloid metaplasia: a single-institution experience with 223 patients.

In a 20-year period, 223 patients (median age, 64.8 years) with myelofibrosis with myeloid metaplasia (MMM) had therapeutic splenectomy at our institution. Primary indications for surgery were transfusion-dependent anemia (45.3%), symptomatic splenomegaly (39. 0%), portal hypertension (10.8%), and severe thrombocytopenia (4.9%). Operative mortality and morbidity rates were 9% and 31%, respectively. The 203 survivors of surgery had a median postsplenectomy survival time (PSS) of 27 months (range, 0-155). Among preoperative variables, thrombocytopenia (platelet count less than 100 x 10(9/)L) and nonhypercellular bone marrow were identified as independent risk factors for decreased PSS. Durable remissions in constitutional symptoms, transfusion-dependent anemia, portal hypertension, and severe thrombocytopenia were achieved in 67%, 23%, 50%, and 0% of the patients, respectively. Histologic or cytogenetic features of bone marrow obtained before splenectomy did not predict a response in cytopenias. After splenectomy, substantial enlargement of the liver and marked thrombocytosis occurred in 16.1% and 22.0% of the patients, respectively. The thrombocytosis was associated with an increased risk of perioperative thrombosis and decreased PSS. The rate of blast transformation (BT) was 16.3%, and the risk of BT was higher in the presence of increased spleen mass and preoperative thrombocytopenia. However, the PSS of patients with BT was not significantly different from that of patients without BT. We conclude that presplenectomy thrombocytopenia in MMM may be a surrogate for advanced disease and is associated with an increased risk of BT and inferior PSS. However, the development of BT after splenectomy may not affect overall survival and does not undermine the palliative role of the procedure for the other indications.

Adolescent↗
PubMed2000

Phase II evaluation of continuous-infusion 5-fluorouracil, leucovorin, mitomycin-C, and oral dipyridamole in advanced measurable pancreatic cancer: a North Central Cancer Treatment Group Trial.

At present there remains a need for more effective systemic therapy in advanced pancreatic cancer. Some studies have suggested that infusional chemotherapy schedules and biomodulation of 5-fluorouracil (5-FU) may improve the therapeutic outcome in advanced colon cancer. One such regimen that uses continuous infusion 5-FU, weekly leucovorin, daily dipyridamole, and intermittent mitomycin-C has activity in both colon and unresectable pancreatic carcinoma. The intent of this trial was to test the effectiveness of this four-drug regimen in advanced pancreatic cancer. Patients received 5-FU 200 mg/m2 daily by continuous infusion, leucovorin 30 mg/m2 IV weekly, mitomycin-C 10 mg/m2 day 1, and dipyridamole 75 mg orally four times daily for 5 weeks. After a 1-week break, treatment cycles were repeated every 6 weeks. Eligibility included biopsy-proven advanced measurable pancreatic cancer, Eastern Cooperative Oncology Group performance status 0 and 2, and no prior systemic chemotherapy. Of 46 evaluable patients, 9 partial responses and 1 complete tumor response were seen, for an overall response rate of 22% (95% confidence interval 11-36%). The median survival in the group of 50 patients registered to this trial was 4.6 months, with a range of 0.33 to 40.2 months. Toxicity was manageable, with the most common toxicities (> or =grade III National Cancer Institute Common Toxicity Criteria) being anorexia (13%), stomatitis (17%), and hand-foot syndrome (13%). Of note, little severe hematologic toxicity and no significant headaches were reported. Although some patients did respond, the therapeutic results are not encouraging enough to take this regimen to phase III testing.

Adult↗
PubMed2000

A randomized, placebo-controlled study of outpatient premedication for bone marrow biopsy in adults with lymphoma.

The outpatient bone marrow biopsy and aspiration (BMBA) procedure performed with local anesthetic is often poorly tolerated in adults. This prospective, randomized, placebo-controlled, double-blind trial was designed to determine whether oral (p.o.) lorazepam and hydromorphone reduces pain and anxiety during BMBA. Eligible patients had lymphoma, had no prior BMBA, and were > or = 18 years old. Since patients had bilateral BMBA, each served as their own control. Patients were stratified by anxiety level using the Spielberger Trait Anxiety Scale and randomized to: A) placebo for the first BMBA and 2 mg lorazepam and 2 mg hydromorphone p.o. for the contralateral BMBA, or B) placebo for both BMBAS. Changes in pain and anxiety experienced between the first and second BMBA were measured by the Visual Analogue Scale (VAS) and the Spielberger State Anxiety Scale at the time of the BMBA and 24 hours later. Twenty-seven patients were enrolled and 25 were evaluable; there were 17 males and eight females. The median age was 57 years (range, 28-79 years). Overall, BMBA was reported as painful in both arms, with a median VAS pain score after the second BMBA of 3.9 (scale, 0-10) for arm A and 5.8 for arm B (P = 0.21). There was no difference in the change in pain, anxiety, or recalled anxiety between treatment arms (all P values > 0.05). The difference in the change in recalled pain was of borderline significance (P = 0.07) and consistent with benzodiazepine-induced anterograde amnesia.

Administration, Oral↗
PubMed2000

Phase III evaluation of octreotide versus chemotherapy with 5-fluorouracil or 5-fluorouracil plus leucovorin in advanced exocrine pancreatic cancer: a North Central Cancer Treatment Group study.

There continues to be a need for new systemic approaches for the treatment of advanced pancreatic cancer. The purpose of this study was to compare the antitumor activity of the somatostatin analogue octreotide to 5-fluorouracil chemotherapy in a Phase III setting. Eighty-four patients with an Eastern Cooperative Oncology Group performance status of 0 or 1 and limited tumor volume were randomized to receive octreotide 200 microg three times daily or 5-fluorouracil with or without leucovorin. After the first 12 patients had been randomized to octreotide, we increased the dose in the remaining patients to 500 microg three times daily. This change was based on early reports in other studies, suggesting that our original dose may not have been effective and that higher doses of octreotide were well tolerated. A planned interim analysis performed after 84 patients were enrolled demonstrated inferior time to progression and survival for the patients randomized to octreotide. Further accrual to the octreotide arm of this protocol was therefore terminated. Octreotide in doses of 200-500 microg three times daily does not delay progression or extend survival in patients with advanced pancreatic cancer compared with treatment with 5-fluorouracil with or without leucovorin.

Adult↗
PubMed1999

Phase I study of 5-fluorouracil administered by protracted venous infusion, leucovorin, and pelvic radiation therapy.

BACKGROUND: This study was designed to assess the toxicity of pelvic radiation therapy, 5-fluorouracil (5-FU) administered by protracted venous infusion, and leucovorin. METHODS: Pelvic radiation therapy consisted of 50.4-54 gray (Gy) administered in 28-30 fractions. Systemic treatment consisted of leucovorin (10 mg daily) administered orally and protracted venous infusion of 5-FU. The initial daily 5-FU dose was 150 mg/m(2). Dose escalations were planned in increments of 25 mg/m(2). RESULTS: Forty eligible patients were registered, of whom 37 were evaluable for chemoradiotherapy-related toxicity. Grade 3 or 4 toxicity secondary to radiation therapy, protracted venous infusion of 5-FU, and leucovorin occurred in 2 of 17 patients at a daily 5-FU dose of 150 mg/m(2), in 5 of 10 patients at a daily 5-FU dose of 175 mg/m(2), and in 5 of 10 patients at a daily 5-FU dose of 200 mg/m(2). Diarrhea was dose-limiting in 7 of 8 patients with Grade 4 toxicity. Venous thrombosis, a treatment-related complication not directly related to chemotherapy or radiation therapy, occurred in 5 of the 40 patients entered into this study. Four thromboses occurred at the site of a central catheter. No thrombotic complications occurred in the last 7 patients, who were given warfarin orally (1 mg daily) during treatment. CONCLUSIONS: Toxicity due to radiation therapy, protracted venous infusion of 5-FU, and leucovorin when 5-FU is given daily at a dose of 150 mg/m(2) is similar to that observed in current chemoradiotherapy regimens for patients with rectal carcinoma. This regimen will be considered as a possible investigational treatment arm of a future trial of adjuvant therapy for rectal carcinoma patients.

Antineoplastic Combined Chemotherapy Protocols↗