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Biomedical subjects

R Bell

Publications and source records attributed to R Bell.

At least 289 records · Page 16Linked to original sources
PubMed1983

The availability and current use of marijuana among adults.

The bulk of previous research on marijuana use shares three common features. First, it focuses on "high-risk" student or adolescent populations. Second, researchers have emphasized the "ever-used" category of marijuana use. Third, reported use rates are generally based on the percentage of users in the total population of interest. By using the total population as the denominator when calculating use rates, researchers assume that everyone has an equal opportunity to smoke marijuana. This paper suggests using a use-availability ratio to adjust for potential access to marijuana and to determine which segments of the population are "high risk."

Adult↗
PubMed1983

Exploring dimensions of access to medical care.

This paper examines the dimensions of the access concept with particular attention to the extent to which more parsimonious indicators of access can be developed. This process is especially useful to health policy makers, planners and researchers in need of cost-effective social indicators of access to monitor the need for and impact of innovative health care programs. Three stages of data reduction are used in the analysis, resulting in a reduced set of key indicators of the concept. Implication for subsequent data collection and measurement of access are discussed.

Consumer Behavior↗
PubMed1982

Short-term treatment for acute myelogenous leukaemia.

Short-term treatment with doxorubicin, cytarabine, and 6-thioguanine was given to 91 consecutive adults with acute myelogenous leukaemia. Fifty patients received high doses (regimen I) and 41 very high doses (regimen II). Where possible, six treatment cycles were given (total dose of doxorubicin 450 mg/m2) regardless of the number of cycles required to achieve complete remission. No additional treatment was given. The remission rate was significantly higher with regimen I than with regimen II (34/50 compared with 15/41, p less than 0.01), the latter, more intensive regimen being associated with a greater incidence of fatal infection (13/41 compared with 5/50, p less than 0.01). Duration of remission was, however, significantly longer with regimen II (p less than 0.05); the median has not yet been reached after a minimum follow-up of two years. Intensive short-term treatment is a feasible strategy for the treatment of acute myelogenous leukaemia.

Adolescent↗
PubMed1982

A comparison of two schedules of cytosine arabinoside used in combination with adriamycin and 6-thioguanine in the treatment of acute myelogenous leukemia.

The most effective schedule of cytosine arabinoside (Ara-C) administration remains controversial and is further confused by the use of combination chemotherapy. Two remission induction regimens comprising adriamycin, Ara-C, and 6-thioguanine have been compared in patients with acute myelogenous leukemia. Administration of Ara-C by continuous intravenous infusion resulted in faster clearing of leukemic blasts from the peripheral blood and bone marrow than after administration of the same dose by twice daily intravenous injection. Myelosuppression and gastrointestinal toxicity were, however, more pronounced when Ara-C was given by infusion. The complete remission rate was higher in the patients treated with intravenous infusions. It is too early to assess the duration of remission in the infusion study; however, despite the relatively low remission rate, 80% of patients under the age of 60 in the intravenous bolus study remain in remission with a minimum follow-up of two years.

Adult↗
PubMed1982

Chromatographic forms of terminal deoxynucleotidyl transferase in normal lymphoid cells and in leukemia cells at presentation and relapse.

Normal thymocyte and bone marrow terminal deoxynucleotidyl transferase (TdT) have distinguishing characteristics by phosphocellulose chromatography in Tris buffer: marrow TdT elutes as a single peak at 0.3 M salt, whereas thymocyte TdT separates into two forms, one at 0.3 M salt and one at 0.4 M salt. Since the majority of TdT-positive acute leukemias are anatomically bone marrow-derived, one would have predicted the presence of a bone marrow TdT-phosphocellulose chromatographic pattern in such patients. However, in 376 consecutive, untreated TdT-positive acute lymphoblastic leukemias (ALL) studied by us we have invariably encountered the two-peak thymocyte-type phosphocellulose pattern. The TdT patterns in the thymic-dependent, TdT-positive lymphoma of AKR mice, and the TdT-positive bone marrow-derived, thymic-independent Abelson virus leukemia of Balb/C mice duplicate the situation in human ALL: a thymocyte pattern is seen in both the marrow-derived and thymus-derived diseases. This chromatographic difference between leukemia-associated and normal marrow-associated TdT in both murine and human leukemia suggested that phosphocellulose-TdT patterns might be useful for monitoring residual marrow tumour cell burden in TdT-positive leukemia. This has not turned out to be the case: in eight patients studied in early relapse the blast cell TdT pattern was the single-peak 0.3 M species. Therefore, leukemic cell TdT cannot reliably be distinguished from normal marrow cell TdT. The chromatographic behaviour of TdT may be regulated by phosphorylation-dephosphorylation, the 0.3 M salt peak can be converted to the 0.4 M salt species by treatment with protein kinase and ATP, and the 0.4 M species can be converted to the 0.3 M form by exposure to alkaline phosphatase. Thus, apparently anatomic compartment-specific forms of TdT may only reflect differing cellular metabolic activity.

Adolescent↗
PubMed1982

Application of Jackson, Aspden Acute Myeloid Leukaemia model.

The comparison of a series of small clinical trials into the treatment of Acute Myelogenous Leukaemia at St Bartholomew's Hospital, London, is described using a previously published mathematical model. The work demonstrates the value of a coherent presentation and analysis of available information in assisting clinicians in their decision-making.

Clinical Trials as Topic↗
PubMed1982

A therapeutic comparison of ipratropium bromide and salbutamol in asthmatic patients.

A single-blind, crossover study was carried out in 43 asthmatic patients to compare the efficacy and tolerance of inhaled ipratropium bromide with inhaled salbutamol. One or other drug was given 3-times daily (0.04 mg ipratropium bromide or 0.2 mg salbutamol per dose) over a period of 4 weeks. Patients were then crossed over to the alternative medication for a further 4 weeks. The results of lung function tests performed at routine clinic visits and by the patients at home showed similar increases in peak flow and spirometry recordings, although more patients expressed a preference for salbutamol. Unwanted effects were minor with both drugs. It is suggested, therefore, that ipratropium bromide may be a useful alternative to beta-stimulants in some asthmatics.

Adult↗
PubMed1982

Colonic lymphoma producing alpha-chain disease protein.

Alpha-chain disease with involvement of small intestine-resulting in characteristic villus atrophy and malabsorption has not been reported in this country. We studied a 57-yr-old male who presented with a polypoid tumor of the hepatic flexure of the colon. There was no evidence of malabsorption as manifested by a normal fat balance, serum carotene, and D-xylose absorption studies and the small bowel biopsy did not show villus atrophy. The tumor in the colon was surgically removed and diagnosed as a malignant lymphoma of lymphocytic type. Tumor tissue infiltrated in the mesentery could not be excised. Alpha-chain disease protein was demonstrated in serum and urine, and also in tumor tissue by immunoperoxidase techniques. The alpha-chain disease protein was further purified and classified as subclass 1. The patient had a good clinical response to cyclophosphamide and prednisone, but still has intraabdominal lymphoma with gastric involvement, and his serum alpha-chain protein persists. This case report may represent a distinct variant of alpha-chain disease.

Colonic Neoplasms↗
PubMed1982

Abnormal glucocorticoid receptors in acute leukemia cells.

In normal tissues, 3H-triamcinolone acetonide (3H-TA) labeled glucocorticoid receptors can be resolved into 2 components by DEAE chromatography: peak I elutes at 0.04 M salt and peak II at 0.22 M salt. By glycerol gradient centrifugation, peak I is 3.5S and peak II is 8.5S. Peak I binds to DNA, while peak II does not. Blast cell 3H-TA-binding macromolecules in 27 of 62 cases of acute leukemia had DEAE binding characteristics identical to those of normal tissues; the remaining 35 cases were abnormal. In these cases there was either a single DEAE species eluting in the peak I area (30 cases) or multiple low-amplitude peaks eluting across the entire gradient (5 cases). The abnormal single peak material failed to bind to DNA in 5 cases (of 5 studied), whereas peak I material from 5 cases (of 5 studied), showing normal peak I-peak II ratios, bound normally to DNA. In 3 cases (of 3 studied), the abnormal single peak material had an S value of 2-2.5S, whereas in 5 cases with normal peak I-peak II ratios, the S values were 3.5S and 8.5S, respectively. We hypothesize that those leukemias with abnormal binder characteristics cannot respond to glucocorticoid therapy.

Acute Disease↗
PubMed1982

Phase II study of a high-dose regimen of cyclophosphamide and prednisolone in advanced non-Hodgkin's lymphoma of favorable histologic type.

Fifty-seven courses of cyclophosphamide (2.5-5.0 g/m2) and prednisolone (1.0 g/m2 x 5) were given to 22 patients with advanced stage IV non-Hodgkin's lymphoma of favorable histology. Six patients (27%) had a complete response (CR) (median duration, 10.1 months), and six (27%) had a partial response (median duration, 3.0 months). All patients in whom CR was achieved had a previous disease pattern of remission and relapse, and no patient refractory to previous therapy had a CR. This association of CR to disease pattern was statistically significant (P less than 0.0001). There was no difference in the survival of complete and partial responders. There was a trend to a higher response rate and statistically significant survival advantage (P less than 0.05) for patients with the nodular histologic types. The transient nature of response and the toxicity of the regimen, with four therapy-related deaths, render it unsuitable as routine therapy.

Adult↗
PubMed1981

A cross-matching procedure for the selection of platelet donors for alloimmunized patients.

A platelet cross-matching procedure has been assessed for selecting compatible donors for alloimmunized patients. This confirms the clinical value of combining an indirect platelet immunofluorescence test (PIFT) with a lymphocytotoxicity test (LCT) in predicting the survival of single-donor platelets. There was good agreement between the PIFT cross-match and post-transfusion platelet recovery. Compatibility in the LCT alone was insufficient for platelet donor selection, as this test did not detect all antibodies affecting platelet survival. Positive LCT and PIFT cross-matches indicated the presence of HLA antibodies. Inclusion of an indirect lymphocyte immunofluorescence test (LIFT) helped to classify the platelet antibody when the LCT cross-match was negative. In such cases, parallel positive findings with the LIFT and PIFT suggested a cytotoxic-negative antibody of probable HLA specificity active against platelets. Disparity between the LIFT and PIFT was also observed; a strongly positive PIFT along with a weak reaction in the LIFT suggested that a platelet-specific antibody was responsible for the poor platelet survival in these cases. This study has also shown the presence in multitransfused patients of LIFT-positive antibodies not reacting in the LCT and PIFT, which do not affect the survival of transfused platelets. A positive granulocyte cross-match was demonstrated in patients with febrile rigors associated with compatible platelet transfusions. Splenectomy and steroids may improve the survival of incompatible platelets depending on the nature of the platelet antibody.

Adult↗