Biomedical subjects
Publications and source records attributed to G Strauss.
This article discusses the recently instituted PACT (Prevention Amputation Care and Treatment) program now being used at the Cleveland Veterans Affairs Medical Center. This program is a multidisciplinary interventional prevention strategy that includes both physical and psychosocial components, addressing the long-term after-care for patients postamputation and preventive interventions for those at risk.
The development of reliable methods for monitoring the reproductive cycle of bears is needed to optimise breeding management in captivity. The aim of the present study was to develop non-invasive procedures for obtaining basic data on the reproductive status of nonpregnant and pregnant bears. Eight female captive bears (five Ursus arctos arctos, two Tremarctos ornatus and one Melursus ursinus) were examined using transrectal adaptor ultrasonographic imaging. Plasma concentrations of progesterone and gestagens in faeces were determined simultaneously. The ultrasonographic appearance of the female urogenital tract was assessed during the nonbreeding season and verified in four adult bears post mortem. Pregnant bears were examined twice, as the reproductive physiology of bears is characterized by delayed implantation and pseudopregnancy. During embryonic diapause there was no difference between pseudopregnant and pregnant bears both by ultrasonographic imaging and endocrinological data. After implantation (early December) the pregnancies were visualised by ultrasonographic imaging, whereas plasma concentrations of progesterone and gestagens in faeces had not yet increased. In conclusion, both transrectal ultrasonographic imaging and gestagen monitoring in faeces are efficient methods for obtaining important data on reproduction in bears.
Familial clustering of autoimmune thyroid diseases has led to studies of their association with human major histocompatibility complex (MHC) class II genes. One such gene implicated in Hashimoto's thyroiditis (HT) is HLA-DR3, but the association is weak and is contradicted by other reports. On the other hand, murine experimental autoimmune thyroiditis (EAT), a model for HT, presents a clear linkage with MHC class II. Moreover, it is inducible with thyroglobulin (Tg), the common autoantigen in either species. Immunization of HLA-DRB1* 0301 (DR3) transgenic mice with mouse or human Tg resulted in severe thyroiditis. In contrast, transgenic mice expressing the HLA-DRB1*1502 (DR2) gene were resistant to EAT. Our studies show that HLA-DRB1 polymorphism determines susceptibility to autoimmune thyroiditis and implicate Tg as an important autoantigen.
To develop an effective immunotherapy for B-lineage acute lymphoblastic leukemia (ALL), bispecific monoclonal antibodies (bsAb) were raised by cell fusion of two hybridoma cell lines secreting CD3 and CD19 antibodies. The resulting bispecific antibody contains two different specificities within a single antibody molecule. One binding site (CD3) activates the T cells via the T cell receptor complex, whereas the second binding site (CD19) targets the cytolytic T cells to malignant B cells. Leukemic blasts from children with B-lineage ALL showed stable and strong CD19 expression. CD3xCD19 bsAb were used to activate peripheral blood mononuclear cells (PBMC) from healthy donors or from patients with ALL during remission. Cytotoxic activity against autologous ALL cells by PBMC was induced upon addition of 100 ng/ml CD3xCD19 bsAb after 3 days of preincubation. Costimulation through CD28 increased T cell proliferation to some extent, but did not increase cytotoxic activity of PBMC against leukemic blasts. We present evidence for an effective and specific activation of resting human T lymphocytes by CD3xCD19 bsAb in vitro. Activation of cytotoxic effector T cells is feasible by preincubation with bsAb CD3xCD19 alone and does not rely on additional external costimulation. Thus, targeting of T cell cytotoxicity towards leukemic blasts via CD3xCD19 bsAb may represent a promising strategy for immunotherapy of B-lineage ALL.
OBJECTIVE: Rates of psychiatric hospitalization and lengths of stay for adolescents have been a focus of recent controversy. With the advent of managed care, hospital systems and third-party payers are looking for ways to decide when hospitalization is indicated. The authors sought to determine whether experts could agree on the appropriateness of putative indicators for hospitalization of adolescents for conduct disorder or substance abuse. METHOD: Using a methodology developed at the Rand Corporation and previously applied to procedures in medicine and surgery, the authors developed a list of possible indications for hospitalization of adolescents with conduct disorder and/or substance abuse. A nine-member panel of experts in these areas, balanced by geography, academics/clinical practice, and whether the expert was in charge of a hospital unit, then rated the appropriateness of each indication twice under a modified Delphi procedure. RESULTS: Using prespecified definitions for agreement, after the initial rating the panel had low levels of disagreement (11%) and moderate levels of agreement (28%) on more than 1,900 possible indications for hospitalization. Despite an expanded number of indications, the panel reduced disagreement to less than 5% and increased agreement to more than 55% after the second round of ratings. CONCLUSIONS: The consensus achieved compared favorably with the results of similar panels judging the appropriateness of procedures in medicine and surgery. The methodology is applicable to studies of the appropriateness of pharmacological or psychotherapeutic interventions in both child and adult psychiatry. The results of such studies can form the basis for rational utilization review and treatment authorization decisions.
BACKGROUND: Cisplatin, 5-fluorouracil, and leucovorin (PFL) have demonstrated synergistic activity in preclinical models. Continuous infusion of these agents maximizes the potential for synergistic interaction and forms the basis of the PFL regimen. METHODS: Sixty-one patients with advanced (Stages IIIB and IV) non-small cell lung cancer were entered into the study. Thirty-one were treated with cisplatin 25 mg/m2/day on days 1-5, 5-fluorouracil 800 mg/m2/day on days 2-6, and calcium leucovorin 500 mg/m2/day on days 1-6. Because of severe mucositis, the final 30 patients were treated with the same dosage of cisplatin but with the deletion on day 6 of leucovorin and 5-fluorouracil. Cycles were repeated every 28 days. Response was assessed after two cycles. Responding patients received an additional two cycles. Patients with Stage IIIB disease received radiation therapy to the mediastinum and sites of involved disease. RESULTS: PFL had an overall response rate of 41%. Median survival was 8.1 months, and median time to treatment failure was 4.2 months. Importantly, 68% (17 of 25) of responses were maximal after just two cycles of chemotherapy. Notable toxicities included mucositis (43% > or = Grade 3) and myelosuppression. Response, time to failure, or survival did not differ between the two schedules. Mucositis was less severe with 4-day PFL. CONCLUSIONS: PFL as given in this manner is an active regimen for the treatment of patients with advanced non-small cell lung cancer. The rapidity of response makes it a regimen for incorporation into protocols for Stage IIIA disease. A neoadjuvant study using PFL is underway.
Patients with non-small-cell lung cancer (NSCLC) were treated with ICE chemotherapy (ifosfamide 2000 mg/m2, days 1-3; carboplatin 300 mg/m2, day 1; etoposide 75 mg/m2, days 1-3) intravenously (i.v.) during the first 3 d of a maximum of four 28 d treatment cycles. Interleukin-3 (IL-3) was administered in cycles 2 and 4 as a daily subcutaneous (s.c.) injection on days 5-18. Cohorts of three patients were treated at dosage levels of 0.5, 1.25, 2.5, 5.0, 10.0 and 15.0 micrograms/kg/d. At 15.0 micrograms/kg/d a 'flu-like' syndrome of myalgias, arthralgias and fatigue was considered dose-limiting. Other toxicities were headache, fever, urticaria, arrhythmia, chills and flushing. Subsequently, nine patients were added to the group receiving 10 micrograms/kg/d. 27 patients received IL-3 after their second course of ICE. At 10 and 15 micrograms/kg/d, IL-3 in cycle 2 was associated with enhanced haematological recovery. Depth of neutrophil nadir and days of neutropenia (ANC < 0.5 x 10(9)/l) were reduced in 9/13 patients and in 8/11 patients, respectively. No effect was seen on platelet nadir or days of thrombocytopenia. IL-3 was well tolerated up to 10 micrograms/kg/d when given as a daily s.c. injection. Results suggest IL-3 as a potential adjunct to chemotherapy, and further studies to explore administration of IL-3 in combination with other cytokines in this setting are warranted.
A 57-year-old woman with a slowly growing intraabdominal leiomyosarcoma developed life-threatening hypoglycaemia. Plasma C-peptide levels were low (0.08 nmol L-1 and < 0.05 nmol L-1, reference interval 0.18-0.63 nmol L-1). Total IGF-II was normal (760 ng mL-1) whilst 'big' IGF-II was markedly elevated (440 ng mL-1). After surgical tumour reduction, 'big' IGF-II levels in plasma normalized (117 ng mL-1) and the patient experienced no new episodes of hypoglycaemia. Life-threatening hypoglycaemia due to tumour production of IGF-II can be ameliorated by reduction of the tumour burden and should be kept in mind even in incurable patients.
PURPOSE: Topotecan is an inhibitor of topoisomerase I that has shown preclinical activity against non-small-cell lung cancer (NSCLC). This phase II study was designed to determine the clinical activity and toxicity spectrum of topotecan in untreated patients with metastatic NSCLC. PATIENTS AND METHODS: Twenty previously untreated patients received topotecan every 21 days at the dose of 2 mg/m2/d intravenously (IV) for 5 days for two cycles, at which point response was assessed. Patients with either clinical response or stable disease (SD) received additional cycles of the drug until toxicity developed or disease progression (PRG) occurred. RESULTS: This study was designed to enter 30 patients. However, because no clinical responses were seen in the first 20 patients entered onto the study, the early-stopping rule was invoked and patient accrual was halted. Eleven patients (55%) had SD on topotecan, and nine (45%) had PRG. Toxicity included neutropenia and rash. The median survival duration for all patients was 7.6 months. CONCLUSION: We observed no objective clinical responses despite producing high-grade neutropenia. Phase II trials of topotecan using different schedules or higher doses supported by growth factors may clarify the role of topotecan in the treatment of NSCLC. The combination of topotecan with cisplatin and topoisomerase II inhibitors such as etoposide should be explored. Finally, the median survival duration of 7.6 months for 20 patients treated with an agent that failed to produce any obvious clinical responses compares favorably to the survival obtained with combinations of existing agents. This supports the further study of novel compounds in this clinical setting.
The establishment of HLA transgenic mice as models for autoimmune disorders requires that the HLA molecules can be efficiently recognized and mediate positive and negative selection of mouse T cells. This question was investigated in DR3(DRw17) transgenic mice back-crossed to the B10.Q(H-2q) strain which does not form mixed mouse-human class II heterodimers. Here we report that efficient negative selection on DR3(DRw17) molecules was observed for v beta 5, 11, and 13 subpopulations of CD4+T cells, but not for v beta 4, 7, 8, 9, and 10. v beta 5 and 11 cells are also negatively selected by mouse class II E molecules which is the structural homologue to DR molecules. Positive selection on DR3(DRw17) was only observed for v beta 6 cells but this was less efficient than positive selection of v beta 6 cells by E molecules. The data indicate that DR3(DRw17) molecules select similar subgroups of mouse T cells as E molecules although with slightly different efficiency.
We investigated the requirements of positive and negative selection in the thymus for CD8 interaction and the selecting cell type. Thymic epithelial cells are known to mediate positive selection, whereas thymocytes fail to do so. The reason for this failure could be either the low amount of MHC class I molecules on thymocytes or the lack of other properties required for positive selection. To address this question a CD2.Kb transgenic mouse was prepared in which the expression of the Kb gene is under control of the CD2 promoter. In these mice the thymocytes exhibited very high levels of Kb. The mice were crossed with two TCR transgenic mice expressing either the Des.TCR (anti-Kb), which is positively selected on Kk and negatively on Kb, and the 2C.TCR (anti-Ld) with positive selection on Kb and negative on Ld. Despite the high Kb expression on thymocytes in CD2.Kb x 2C.TCR mice no positive selection was observed, whereas efficient negative selection was found in CD2.Kb x Des.TCR F1 mice. Thus, although thymocytes can negatively select, even a strong increase of MHC class I expression cannot convert them into positively selecting cells. This is consistent with the notion that thymic epithelium is specialized for positive selection, but the respective difference between thymocytes and thymic epithelium is not clear. The influence of CD8 was investigated using transgenic mice expressing a Kk/A2 or a Kb/A2 hybrid gene in which the promoter, the alpha 1, alpha 2 domains were of mouse origin and the alpha 3 domain of human origin. Because the murine CD8 molecule does not efficiently bind to human HLA class I, in these mice the CD8 interaction was impaired. In Kb/A2 x 2C.TCR and Kk/A2 x Des.TCR mice no positive selection of the respective TCR was found, whereas in Kb/A2 x Des.TCR mice negative selection was still functional. Altogether, the results indicate that positive selection depends more strictly on CD8 interaction and cell type than negative selection.
The phototrophic bacterium Chloroflexus aurantiacus does not use any of the known autotrophic CO2 fixation pathways. There is evidence for a new cyclic autotrophic pathway in which acetyl-CoA is converted to 3-hydroxypropionate and further to succinate and malate. This hypothesis was tested by feeding growing cultures during several generations with 3-hydroxy[1-13C]propionate, [1-13C]acetate, or [2-13C]acetate, in addition to unlabeled CO2. The relative 13C content of individual carbon atoms in biosynthetic amino acids and nucleosides was determined by 1H- and 13C-NMR spectroscopy. 13C coupling patterns were analyzed by two-dimensional 13C-TOCSY experiments which were optimized for the analysis of multiply 13C-labeled biosynthetic samples. From the 13C enrichments of amino acids and nucleosides, the labeling patterns of central metabolic intermediates were evaluated by a retrobiosynthetic approach. Both 3-hydroxypropionate and acetate were incorporated into all central metabolic pools. The 13C labeling and coupling patterns suggest a novel carbon fixation pathway via 3-hydroxypropionate. Specifically, we propose that acetyl-CoA is carboxylated to malonyl-CoA which is reduced under formation of 3-hydroxypropionyl-CoA. Dehydration and reduction yield propionyl-CoA which is converted to succinate by a second carboxylation reaction. The net product of autotrophic carbon fixation appears to be glyoxylate. However, it is not yet known how glyoxylate is channeled into anabolic metabolism. Assimilation of acetate can proceed via the CO2 fixation pathway, but also via the glyoxylate pathway.
The phototrophic bacterium Chloroflexus aurantiacus can grow autotrophically but seems not to assimilate CO2 via any of the known autotrophic pathways. Holo [Holo, H. (1989) Arch. Microbiol. 151, 252-256] proposed a new pathway in which 3-hydroxypropionate is formed from acetyl-CoA. Previous studies excluded the operation of known CO2 fixation pathways and provided indirect evidence for the suggested pathway based on 13C-labelling experiments. Here all enzyme activities of the postulated cyclic CO2 fixation mechanism are demonstrated in vitro. In essence, acetyl-CoA is carboxylated and reductively converted via 3-hydroxypropionate to propionyl-CoA. Propionyl-CoA is carboxylated and converted via succinyl-CoA and CoA transfer to malyl-CoA. Malyl-CoA is cleaved to acetyl-CoA and glyoxylate. Thereby, the first CO2 acceptor molecule acetyl-CoA is regenerated, completing the cycle and the net CO2 fixation product glyoxylate is released. This cycle represents the fourth autotrophic pathway in nature and is designated the 3-hydroxypropionate cycle.
BACKGROUND: Cisplatin and etoposide combination chemotherapy is the most commonly used regimen for advanced non-small cell lung cancer (NSCLC). 5-Fluorouracil (5-FU) is an agent with little intrinsic activity against NSCLC: However, there is increasing evidence that 5-FU is synergistic with cisplatin and vice versa. In an effort to improve on the traditional chemotherapeutic approach to NSCLC, a treatment regimen consisting of cisplatin, 5-FU, and etoposide (PFE) was developed. METHODS: Thirty-five patients with advanced NSCLC were treated with the PFE regimen (cisplatin 25/mg/m2/d and 5-FU 1000 mg/m2/d by continuous infusion and etoposide 60 mg/m2/d, each for 4 days). The cycles were repeated every 28 days. RESULTS: The patients received a mean of 2.8 cycles of PFE. Ten patients had a partial response to chemotherapy for an overall response rate of 28.6%. The median survival was 7.0 months. Toxicities included myocardial infarction (2 of 35), congestive heart failure (2 of 35), fatal pulmonary embolus (1 of 35), and a cerebrovascular accident (1 of 35). The incidence of Grade 4 neutropenia (5.7%) and thrombocytopenia (8.5%) was acceptable. CONCLUSIONS: The response rate, duration of response, and survival in this group of 35 patients treated with PFE was similar to that reported for cisplatin and etoposide. The increased cardiovascular toxicity may be the result of the infused 5-FU.
The unresolved autotrophic CO2 fixation pathways in the sulfur-reducing Archaebacterium Thermoproteus neutrophilus and in the phototrophic Eubacterium Chloroflexus aurantiacus have been investigated. Autotrophically growing cultures were labelled with [1,4-13C1]succinate, and the 13C pattern in cell constituents was determined by 1H- and 13C-NMR spectroscopy of purified amino acids and other cell constituents. In both organisms succinate contributed to less than 10% of cell carbon, the major part of carbon originated from CO2. All cell constituents became 13C-labelled, but different patterns were observed in the two organisms. This proves that two different cyclic CO2 fixation pathways are operating in autotrophic carbon assimilation in both of which succinate is an intermediate. The 13C-labelling pattern in T. neutrophilus is consistent with the operation of a reductive citric acid cycle and rules out any other known autotrophic CO2 fixation pathway. Surprisingly, the proffered [1,4-13C1]succinate was partially converted to double-labelled [3,4-13C2]glutamate, but not to double-labelled aspartate. These findings suggest that the conversion of citrate to 2-oxoglutarate is readily reversible under the growth conditions used, and a reversible citrate cleavage reaction is proposed. The 13C-labelling pattern in C. aurantiacus disagrees with any of the established CO2 fixation pathways; it therefore demands a novel autotrophic CO2 fixation cycle in which 3-hydroxypropionate and succinate are likely intermediates. The bacterium excreted substantial amounts of 3-hydroxypropionate (5 mM) and succinate (0.5 mM) at the end of autotrophic growth. Autotrophically grown Chloroflexus cells contained acetyl-CoA carboxylase and propionyl-CoA carboxylase activity. These enzymes are proposed to be the main CO2-fixing enzymes resulting in malonyl-CoA and methylmalonyl-CoA formation; from these carboxylation products 3-hydroxypropionate and succinate, respectively, can be formed.
Because of potential synergistic interactions, we added 25 mg/m2 i.v. cisplatin (P) 25 given on days 1-5 to the combination of 45 mg/m2 i.v. doxorubicin (A) given on day 1, 800 mg/m2 i.v. cyclophosphamide (C) given on day 1, and 50 mg/m2 i.v. etoposide (E) given on days 1-5. The resulting PACE regimen was given every 21 days for the first three courses and then every 28 days for the next five courses. PACE was used in two trials: the first, for both limited and extensive disease, was conducted at the University of Maryland Cancer Center and North Shore University Hospital; and the second, for extensive disease, was carried out as a Cancer and Leukemia Group B pilot study. Chest irradiation was not used. Prophylactic cranial irradiation at a dose of 3,000 cGy was given to all patients achieving a complete response (CR). A total of 33 subjects were entered in the first study; 8 of the 15 (53%) presenting with limited disease and 7 of the 18 (39%) exhibiting extensive disease achieved a CR. A partial response (PR) was obtained in 27% and 33% of cases, respectively. Of the 34 patients entered in the second study, 25 were eligible; 8 (32%) achieved a CR and 6 (24%) showed a PR. Toxicity was severe in both studies, including greater than 90% severe or life-threatening leukopenia and thrombocytopenia. Serial creatinine-clearance evaluations in the first study indicated progressive deterioration, which required discontinuation of the cisplatin before the planned completion of treatment in most cases. Since the response rate was no higher than the historic data reported for the three-drug ACE combination and because the toxicity was severe, the studies were stopped and patients were followed for survival. After a follow-up period of greater than 6 years, the median survival was 24 months for limited disease, with 33% and 27% of the patients being alive at 3 and 6.5 years, respectively. The median survival for extensive disease was 15 and 11 months in the first and second studies, respectively. These pilot studies suggest that the addition of cisplatin may augment the activity of the ACE regimen, but at the cost of severe toxicity. Further studies seem warranted if the myelotoxicity can be better controlled.
A technique for extrapleural pneumonectomy in diffuse, malignant, pleural mesothelioma is described. The technique used in a protocol at Brigham and Women's Hospital has resulted in improved operative mortality figures and length of hospital stay. The right-sided procedure is presented followed by differences in technique required by the left-sided approach.
Operators of hospital sterilizers that use ethylene oxide were studied to determine if there was a relationship between exposure and a battery of biological markers. A total of 73 workers from nine hospitals in the United States (U.S.) and one hospital in Mexico City was evaluated for ethylene oxide exposure during four months prior to collection of peripheral blood. The frequency of hemoglobin adducts (p = 0.0006) and sister-chromatid exchanges (SCEs) (p = 0.002) increased with cumulative exposure to ethylene oxide in U.S. subjects when controlling by regression analysis for various confounding factors, including cigarette smoking. Hemoglobin adducts, but not SCEs, were also increased in Mexican subjects (p = 0.0012). Chromosomal micronuclei showed no consistent relationship with exposure. The U.S. study participants were classified by four-month cumulative exposure levels of 10 ppm-h (n = 8), greater than 0 to 32 ppm-h (n = 32) and greater than 32 ppm-h (n = 11) of ethylene oxide exposure. The group with an exposure of greater than 32 ppm-h had an increased frequency of hemoglobin adducts (p = 0.002) and SCEs (p = 0.0001) compared to the nonexposed group. The estimated mean of the 8-h time-weighted average (8-h TWA) exposure levels for the highest U.S. exposure group (greater than 32 ppm-h) was 0.16 +/- 0.007 ppm (mean +/- SD). A similar exposure-related differential was observed in the Mexican subjects for hemoglobin adducts (p = 0.04) but not for SCEs. The latter finding may have been due to longer shipping times for the specimens in the cytogenetic assays. The estimated mean of the 8-h TWA exposure levels for the highest Mexican exposure group (greater than 32 ppm-h) was 0.48 +/- 0.08 ppm. This study is the third to suggest that exposures less than the U.S. OSHA standard of 1 ppm 8-h TWA result in biochemical and biologic changes. It is not known whether these changes may be indicative of increased risk of disease; however, they do appear to reflect exposure to relatively low levels of ethylene oxide. The exact meaning of these changes is unknown.