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Biomedical subjects

T Walsh

Publications and source records attributed to T Walsh.

At least 73 records · Page 4Linked to original sources
PubMed1995

Monotherapy for fever and neutropenia in cancer patients: a randomized comparison of ceftazidime versus imipenem.

PURPOSE: To compare the efficacy of ceftazidime and imipenem monotherapy for fever and neutropenia, and to determine whether fewer antimicrobial modifications (additions or changes) are required by the broader-spectrum agent, imipenem. PATIENTS AND METHODS: Adult and pediatric patients undergoing chemotherapy for solid tumors, leukemias, or lymphomas were randomized to receive open-label ceftazidime or imipenem on presentation with fever and neutropenia. Success with or without modifications of the initial antibiotic was defined as survival through neutropenia; failure was death due to infection. Comparisons were based on numbers of modifications made to each monotherapy during the course of neutropenia, in patients stratified as having unexplained fever or a documented infection. RESULTS: Among 204 ceftazidime and 195 imipenem recipients, the overall success rate with or without modification was more than 98%, regardless of initial antibiotic regimen. Modifications occurred in half of all episodes, primarily in patients with documented infections on either monotherapy. Antianaerobic agents were more frequently added to ceftazidime (P < .001), but addition of other antibiotics, including vancomycin and aminoglycosides, was similar between the two monotherapy groups. Imipenem therapy was associated with significantly greater toxicity, manifested by Clostridium difficile-associated diarrhea and by nausea and vomiting, which required discontinuation of imipenem in 10% of recipients. CONCLUSION: Ceftazidime and imipenem are both effective in the management of fever and chemotherapy-related neutropenia, provided that modifications are made in response to clinical and microbiologic data that emerge during the course of neutropenia. Imipenem, despite its broader antimicrobial spectrum, does not significantly decrease the overall need for antibiotic modifications and is more often complicated by gastrointestinal toxicity.

Acyclovir↗
PubMed1994

Expression of tissue kallikrein in human kidney.

1. We studied the distribution of human tissue kallikrein mRNA in normal and diseased kidney, using in situ hybridization, together with immunohistochemical localization of renal kallikrein protein. Materials studied were (a) normal tissue from kidneys removed because of localized renal carcinoma, (b) kidneys removed because of post-traumatic haemorrhage and (c) renal biopsy specimens from patients with membranous glomerulonephritis and nephrotic syndrome. 2. A 1.35 kb EcoRI fragment of human tissue kallikrein cDNA was labelled with [32P]dCTP using the random-primer technique, and used for in situ hybridization. A specific rabbit antibody to active human urinary kallikrein was employed for immunocytochemistry, using a peroxidase-antiperoxidase method. 3. By in situ hybridization, no tissue kallikrein gene expression was seen in the carcinoma nephrectomy specimens. Positive expression was seen in the trauma nephrectomy tissue, and in four of five nephrotic syndrome biopsies. In all kidneys, expression was confined to the renal cortex. The dominant site of gene expression was the distal tubule. Apart from one area of positive signal related to an epithelial cell of Bowman's capsule, expression was not observed in glomeruli. Expression was also seen in the walls of large- and medium-sized blood vessels. 4. By immunohistochemistry, the dominant site of immunoreactivity was the distal tubule. Dense staining was also seen in granular peripolar cells and in isolated parietal epithelial cells close to the vascular pole. Isolated immunoreactive cells were seen in the media of large- and medium-sized arteries. 5. The tissue kallikrein gene in the kidney may not be constitutively expressed, but is expressed in response to physiological or pathological stimuli.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The correct dose: pharmacologically guided end point for anti-growth factor therapy.

Strategies to block the effects of tumor growth factors, such as estrogen, and to recruit other regulatory elements, such as with retinoids, have focused interest on the possibility of successful tumor intervention approaches. Approaches that neutralize the effects of critical molecules that drive tumor promotion are attractive targets for evaluation as new intervention agents. Clinical intervention trials with early stage patients or with subjects from "high risk" populations impose stricter types of constraints than conventional chemotherapy approaches in advanced stage patients. The potential for short-term toxicity has to be considered, as it may affect subject accrual or compliance. The longer expected survival of intervention subjects mandates closer attention to the possibilities of unexpected long-term toxicities with chronic administration of an intervention agent. As part of a Phase I clinical trial evaluating the utility of a monoclonal antibody directed against the autocrine growth factor, gastrin-releasing peptide to block the growth of small cell lung cancer, we developed a mathematical model to predict the requisite amount of antibody to neutralize growth factor effect. This model requires knowledge of the equilibrium concentration of the secreted growth factor, specific receptor, and bioavailability of the antibody in the tumor interstitium. A range of possible target doses of antibody can be developed to address the potential for heterogeneity frequently encountered in such systems, including a range of levels for peptide production and specific receptor expression. This approach could be applied to rationally derive treatment or intervention in which specific information regarding the relevant binding parameters is available. Through refinement of this modeling approach more context-specific dosing of agonist/antagonists could be determined which may decrease side effects associated with the drug administration.

Antibodies, Monoclonal↗
PubMed1991

The association of lipid abnormalities with tissue pathology in human osteoarthritic articular cartilage.

Articular cartilage is one of very few body tissues uniquely characterized as having substantial stores of lipid deposits. Lipid droplets are naturally accumulated by chondrocytes and individual fatty acids have been shown to have protective as well as deleterious effects on cartilage degradation in animal models of degenerative joint disease. As a means to better assess the role of lipids in human joint pathology, a comparative analysis of fatty acids was undertaken in small segments of osteoarthritic articular cartilage. The data were assessed in terms of chondrocyte synthetic activity and histological determination of disease severity. The distribution profile of individual fatty acids in normal and osteoarthritic specimens remained constant, with palmitic, oleic, and linoleic acids representing 85% of the total fatty acids. In contrast, levels of total fatty acids were markedly increased in association with increasing degree of lesion severity. Compared with tissue from normal-aged joints, grade 0 to 1 mild lesions had elevated levels of total fatty acids, essential fatty acids, and chondrocyte synthetic activity of 80%, 312%, and 393%, respectively. More severe tissue involvement (grade 6 to 9), was associated with even greater increases of 440%, 1,100%, and 1,150%, respectively. No change was noted in cholesterol content in any tissue. The accumulation of arachidonic acid was greater than the proportional increase in total fatty acid content and was primarily distributed into the neutral lipid fraction, where it constituted almost 62% of the fatty acid level in tissues of moderate lesion severity. There was an association of lipid accumulation in general and arachidonic acid in particular with histological severity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Tumor cell lines established in vitro: an independent prognostic factor for survival in non-small-cell lung cancer.

OBJECTIVE: To determine the relation between in-vitro establishment of tumor cell lines and survival in patients with non-small-cell lung cancer. DESIGN: Cohort study. SETTING: Single-institution tertiary care center. PATIENTS: One hundred twenty-three consecutive patients with non-small-cell lung cancer from whom a viable tumor specimen could be obtained. INTERVENTION: Tumor tissue was removed at the time of entry into a therapeutic protocol. The tumor tissue was processed in the laboratory for attempted cell-line establishment. Patients classified as potentially curable (stages I, II, and IIIA) were treated with surgical resection, radiation therapy, or a combination. Patients suitable for palliative therapy only (stages IIIB and IV) were treated with radiation therapy with or without chemotherapy. Chemotherapy was based on in-vitro drug sensitivity when available. Cell-line establishment was correlated to clinical outcome. MEASUREMENTS AND MAIN RESULTS: Univariate analysis of survival was done using the log-rank test; multivariate analysis was done by Cox modeling step-up and step-down techniques. Cell lines were established from the tumor specimens of 25 patients (20%). Those patients experienced a median survival of 7 months compared with 18 months in patients from whom cell lines could not be established (P less than 0.001). In the 61 patients with potentially curable disease, 8 patients (13%) with cell lines established had a median survival of 8 months compared with 32 months for those without cell lines established (P = 0.001). In the 62 palliative group patients, the median survival of the 17 patients (27%) from whom tumor cell lines were established was 5 months compared with 7 months for those without cell lines (P = 0.15). Multivariate analysis in both groups showed cell-line establishment to be a significant indicator of prognosis (P less than 0.0001 for curable group; P less than 0.01 for palliative group). CONCLUSION: In-vitro tumor growth is related to decreased patient survival, which in turn reflects the biologic aggressiveness of cancers giving rise to these tumor cell lines.

Analysis of Variance↗
PubMed1988

The development of small cell lung cancer in the contralateral lung of a patient surviving 8 years after the original diagnosis of small cell lung cancer.

The development of non-small cell lung cancer in patients successfully treated for small cell lung cancer has been previously described. Many of these non-small cell tumors appear to be second primary lung tumors. However, the development of second primary small cell lung cancers has not been clearly delineated. In this report, a patient with limited stage small cell lung cancer who had a complete response to chemotherapy plus chest radiotherapy and remained cancer-free for 8 years is described. Small cell lung cancer developed in this patient's contralateral lung with no evidence of recurrence at the original primary site. Clinical evidence suggests that a second primary small cell lung cancer developed in this patient.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Immunolymphoscintigraphy of pulmonary and mediastinal lymph nodes in dogs: a new approach to lung cancer imaging.

Despite improved resolution with new imaging techniques, surgical confirmation of mediastinal lymph node status is often required for reliable staging of patients with non-small cell lung cancer. Recent scintigraphic studies suggest that s.c. administration of radiolabeled antibodies can be more efficient than the i.v. route for targeting regional lymph nodes in animals and humans. To determine if this approach could be applied to the lymphatics of the lung, we injected both specific and irrelevant radiolabeled monoclonal antibodies via a flexible fiberoptic bronchoscope through the mucosa of lobar bronchi in normal dogs. The injected antibodies were expected to drain by way of local lymphatic vessels toward the central lymph nodes, in effect following the same pathway as do cells metastasizing to these nodes during early regional tumor dissemination. To accomplish this, anesthetized dogs were intubated and then coinjected with the two labeled antibodies [600 microCi/100 micrograms (total)] through a fiberoptic bronchoscope. The animals were serially imaged and then autopsied 14-36 h after injection. Individual hilar and carinal nodes contained over 1% of the injected 131I-labeled specific antibody dose and the average selectivity was 2.5:1 with respect to a coinjected irrelevant IgG. Distant organs (mesenteric lymph node, liver, spleen, bone marrow, and lung parenchyma other than the injection site) contained much less radioactivity, and those sites accumulated a greater fraction of the non-specific labeled antibody. The ratio of iodine-131 to iodine-125 counts between hilar/carinal lymph nodes and abdominal lymph nodes ranged from 15:1 to 100:1. These initial studies indicate efficient delivery of antibody to a subset of the regional nodes via pulmonary lymphatics. They suggest the feasibility of this technique which may be of use in the detection and perhaps therapy of human lung cancer metastases in regional lymph nodes.

Animals↗
PubMed1987

Calcium currents, charge movement and dihydropyridine binding in fast- and slow-twitch muscles of rat and rabbit.

1. The Vaseline-gap technique was used to record slow calcium currents and asymmetric charge movement in single fibres of fast-twitch muscles (extensor digitorum longus (e.d.l.) and sternomastoid) and slow-twitch muscles (soleus) from rat and rabbit, at a holding potential of -90 mV. 2. The slow calcium current in soleus fibres was about one-third of the size of the current in e.d.l. fibres, but was very similar otherwise. In both e.d.l. and soleus fibres, the dihydropyridine (DHP), nifedipine, suppressed the calcium current entirely. 3. In these normally polarized fibres, nifedipine suppressed only part (qns) of the asymmetric charge movement. The proportion of qns suppressed by various concentrations of nifedipine was linearly related to the associated reduction of the calcium current. Half-maximal suppression of both parameters was obtained with about 0.5 microM-nifedipine. The calcium current and the qns component of the charge movement also were suppressed over the same time course by nifedipine. Another DHP calcium antagonist, (+)PN200/110, was indistinguishable from nifedipine in its effects of suppressing calcium currents and qns. 4. In all muscle types, the total amount of qns in each fibre was linearly related to the size of the calcium current (in the absence of DHP). On average, qns was 3.3 times larger in e.d.l. fibres than in soleus fibres. 5. In contrast to the other dihydropyridines, (-)bay K8644, a calcium channel agonist, did not suppress any asymmetric charge movement. 6. The potential dependence of the slow calcium current implied a minimum gating charge of about five or six electronic charges. The movement of qns occurred over a more negative potential range than the change in calcium conductance. 7. Experiments on the binding of (+)PN200/110 indicated that e.d.l. muscles had between about 2 and 3 times more specific DHP binding sites than did soleus muscle. 8. These results point to a close relationship between slow calcium channels, the qns component of the charge movement and DHP binding sites, in both fast- and slow-twitch mammalian muscle. qns appears to be part of the gating current of the T-system calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗