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Biomedical subjects

D B Johnson

Publications and source records attributed to D B Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Diagnosis and treatment of cervical intraepithelial neoplasia in general practice.

OBJECTIVE: To audit the first five years of a colposcopy and treatment service for cervical dysplasia established within a general practice. DESIGN: A cervical smear register was established to determine which women were "at risk" of dysplasia. The results of colposcopy and treatment of dysplasia were analysed. SETTING: A large rural general practice with community hospital facilities in mid-Wales. PATIENTS: 4437 Women at risk in a total practice population of 14,100. INTERVENTIONS: Colposcopy of women with dyskaryotic smear results, persistent inflammatory smear results, or vulval warts. Treatment of women with proved dysplasia by electrodiathermy of the cervix or cone biopsy. RESULTS: 138 Women with dysplasia were diagnosed over five years: 36 mild, 97 moderate or severe, and five with microinvasion. Despite a 78% smear rate of at risk women over five years, nine invasive cancers still occurred. CONCLUSIONS: The results of treatment are acceptable. Cervical dysplasia has become very common, the risk of a dysplasia in women aged 20-39 who had smear tests being one in 14 over five years.

Adolescent↗
PubMed1989

Ornithine decarboxylase in resting human mononuclear leucocytes: evidence for an endogenous inhibitor.

1. Ornithine decarboxylase (ODC) was measured in human mononuclear leucocytes (HML) by retention of putrescine on cation exchange paper. 2. The method was validated with unstimulated HML, phytohemagglutinin-stimulated HML, and a commercial preparation of ODC. The average enzyme activity of unstimulated HML (50 samples) was 22.6 +/- 7.3 pmol/hr 10(7) cells, with 29 values less than 5 pmol/hr 107 cells. 3. The results show that an endogenous inhibitor or inactivator of ODC exists in unstimulated HML: enzyme activity in extracts of mitogen-stimulated cells were inhibited by extracts of unstimulated cells (37-55%) inhibition under the conditions used.

Cation Exchange Resins↗
PubMed1989

DNA repair synthesis in individuals with and without a family history of cancer.

The influence of family history on DNA repair synthesis, unscheduled DNA synthesis (UDS), was assessed in volunteers with or without a family history of cancer. UDS, following treatment of mononuclear leukocytes with N-acetoxy-2-acetylaminofluorene, was measured as the incorporation of [3H]thymidine into DNA in the presence of hydroxyurea. The positive family history group (n = 71) had an average of 2.4 first-degree relatives with cancer, defined as any major cancer, excluding skin cancer: 31 participants reported that cancer occurred in both their parents. The "no family history' comparison group (n = 29) had no family history of cancer through the second degree. There was a significant reduction in UDS in cells from individuals with family history, compared to those with no family history (P greater than 0.002). This relationship was not explained by factors known to influence UDS, such as age, smoking or hypertension. We conclude that reduced UDS in mononuclear leukocytes is associated with a family history of any major cancer, and is not confined to a history of cancer of any single organ site. This conclusion is further supported by the observation that individuals (n = 13) with parents who had an earlier onset of cancer (less than 60 years) also had a significantly lower DNA repair synthesis than those (n = 18) whose parents had later diagnosis of cancer (greater than 60 years).

Acetoxyacetylaminofluorene↗
PubMed1989

Adenosine diphosphate ribosyl transferase responses to a standardized dose of hydrogen peroxide in the mononuclear leukocytes of patients with a diagnosis of cancer.

Mononuclear leukocytes from 151 patients with cancer of various organs and from 467 apparently cancer-free individuals were exposed, in vitro, to H2O2 (100 microM) and the effects of the exposure on the activity of adenosine diphosphate ribosyl transferase (ADPRT) were determined. First, the reproducibility of this test procedure was established as satisfactory, by comparing the results of assays performed independently by two investigators, and by measuring ADPRT in cells from two individuals over a 9-week period. The test data were analyzed by multiple linear regression, and the correlation of cancer diagnosis, age, sex and smoking habits with ADPRT values was determined. The strongest correlate was cancer diagnosis. We considered categorizing ADPRT values as high and low, with a cut-off value that would substantially distinguish cancer from cancer-free individuals. When a cut-off value of 1200 c.p.m. TCA ppt [3H]NAD+/5 x 10(5) cells was applied to the complete test material, it was found that ADPRT values from cancer patients were more frequently below the cut-off than values from disease-free individuals: the relative risk estimate (odds ratio) was 13.8. When a similar analysis was done on values from lung cancer patients and smoking disease-free individuals, the odds ratio was 73.5. However, a cut-off value of 2000 c.p.m. TCA ppt [3H]NAD+/5 x 10(5) cells was most effective in distinguishing lung cancer patients (the largest cancer group, n = 96) from smoking non-cancer individuals: that value provided better sensitivity (85%) and specificity (81%) than other cut-off values tested in the range 1200-2000 c.p.m. Further, in the case of lung cancer, possible effects of anatomical site, and of staging and pathology on ADPRT values was analyzed by the chi-squared test: no significant associations were found. These data support the value of the ADPRT test in detecting early stage lung cancer regardless of location or pathological type.

Adult↗
PubMed1988

Acute neurologic dysfunction after high-dose etoposide therapy for malignant glioma.

Etoposide (VP-16-213) has been used in the treatment of many solid tumors and hematologic malignancies. When used in high doses and in conjunction with autologous bone marrow transplantation, this agent has activity against several treatment-resistant cancers including malignant glioma. In six of eight patients (75%) who we treated for recurrent or resistant glioma, sudden severe neurologic deterioration occurred. This developed a median of 9 days after initiation of high-dose etoposide therapy. Significant clinical manifestations have included confusion, papilledema, somnolence, exacerbation of motor deficits, and sharp increase in seizure activity. These abnormalities resolved rapidly after initiation of high-dose intravenous dexamethasone therapy. In all patients, computerized tomographic (CT) brain scans demonstrated stability in tumor size and peritumor edema when compared with pretransplant scans. This complication appears to represent a significant new toxicity of high-dose etoposide therapy for malignant glioma.

Acute Disease↗
PubMed1988

Effects of cumene hydroperoxide on adenosine diphosphate ribosyl transferase in mononuclear leukocytes of patients with adenomatous polyps in the colon.

We have studied the effects of plasma and of cumene hydroperoxide (CUM) on adenosine diphosphate ribosyl transferase (ADPRT) from mononuclear leukocytes (HML) of patients with colonic adenomatous polyps (n = 22), with colonic hyperplastic polyps (n = 5) and with neither type of polyp (controls) (n = 6). ADPRT was measured after incubation of HML with plasma alone (termed the plasma value), and with plasma plus CUM (50 microM) (the activated value); the difference elicited by CUM was termed the induced value. There was no significant difference in values between the control and hyperplastic polyp groups: these were combined for further analysis. The plasma (P = 0.038), activated (P = 0.009) and induced (P = 0.0024) values of the combined group all differed significantly from those of the adenoma group. At low exposures, CUM stimulated both ADPRT and unscheduled DNA synthesis and, at higher exposures, inactivated both. Pretreatment of HML with vitamin E protected against these effects of CUM, while pretreatment with diamide (which depletes GSH) accentuated the effects. This study demonstrates a differential reaction of ADPRT in patients harboring colonic adenomas and suggests that the origin of this difference may lie in cellular responses to oxidative stress.

Benzene Derivatives↗
PubMed1987

Prolongation of survival for high-grade malignant gliomas with adjuvant high-dose BCNU and autologous bone marrow transplantation.

Employment of postoperative brain irradiation in the initial management of high-grade malignant glial tumors has now become standard. The addition of conventional chemotherapy to irradiation has not significantly improved median survival beyond 1 year. We treated 25 consecutive patients (13 pilot patients and 12 protocol patients) with histologically confirmed unresectable grade 3 or 4 malignant gliomas with high-dose BCNU (carmustine) followed by autologous bone marrow transplantation and whole brain irradiation. Within 3 weeks of initial surgery, each patient had autologous bone marrow stored (median 2 X 10(8) nucleated cells/kg), and then received BCNU 1,050 mg/m2 intravenously (IV). Peripheral granulocytes recovered (greater than 500/microL) at a median of 19 days (range, 10 to 37 days), and platelets recovered (greater than 20,000/microL) at a median of 18 days (range, 13 to 40 days), following bone marrow infusion. Patients received 60 Gy whole brain irradiation when granulocytes were greater than 1,500/microL. Toxicity was well tolerated. Nausea occurred in 19 patients (76%); however, only eight patients (32%) experienced vomiting (mild in three, moderate in five). Eleven patients (44%) did not require empiric antibiotics, six of whom never developed an absolute granulocyte count less than 500/microL. Three patients with a poor performance status died early (one seizure with vomiting and asphyxiation; one, klebsiella urinary tract infection (UTI) with bacteremia; one, candidal pneumonia), and one additional patient who was performing well died of pulmonary hemorrhage. The 13 pilot patients have now been followed for a median of 23 months, with a significant survival advantage compared with the 52 consecutive historical control patients who received similar surgery and radiotherapy without high-dose BCNU (P = .037). The overall study group of 25 patients also has a significant survival advantage when compared with the same historical control group, with a projected median survival of 26 months (P = .007). This new approach using early postoperative intensive therapy consisting of high-dose BCNU, autologous bone marrow transplantation, and whole brain irradiation appears to significantly improve survival.

Adult↗
PubMed1986

Effect of folinic acid on the capacity of trimethoprim-sulfamethoxazole to prevent and treat Pneumocystis carinii pneumonia in rats.

Daily administration of 1 mg of folinic acid to immunosuppressed rats with incipient or established Pneumocystis carinii pneumonia did not impair the capacity of trimethoprim-sulfamethoxazole to either prevent or treat this disease. These observations constitute the first experimental support for the use of folinic acid to prevent or control cytopenias that occur in patients with Pneumocystis carinii pneumonia who are under trimethoprim-sulfamethoxazole treatment.

Animals↗
PubMed1986

Phase II trial of high-dose melphalan and autologous bone marrow transplantation for metastatic colon carcinoma.

Colon carcinoma, the second leading cause of cancer-related deaths in the United States, is resistant to chemotherapy in a large majority of cases. Single-agent and combination chemotherapy have failed to prolong survival. New approaches are clearly needed. In experimental models, a steep dose-response curve for colorectal cancer has been demonstrated using various agents. The hematopoietic toxicity of high-dose therapy with these drugs can be circumvented by autologous bone marrow transplantation. We investigated the use of high-dose melphalan with autologous bone marrow rescue in 20 patients with metastatic colon carcinoma. Each patient received melphalan, 180 mg/m2 intravenously (IV), followed eight hours later by bone marrow infusion. Median duration of granulocytopenia (less than 500 neutrophils/microL) was twelve days (range, 5 to 35 days), while transfusion-dependent thrombocytopenia (less than 20,000 platelets/microL) had a median duration of eight days (range, 3 to 23 days). Time to bone marrow engraftment was not affected by prior 5-fluorouracil therapy. Nausea and vomiting occurred in 14 patients but was generally short lived. Mild stomatitis, esophagitis, and diarrhea were common. Severe gastrointestinal (GI) side effects did not occur. One treatment-related death occurred secondary to intramural tumor necrosis, which resulted in massive lower GI bleeding. Complete responses were observed in three patients (15%) and partial responses in six patients (30%), for an overall response rate of 45%. Median survival was 198 days in this group of patients with extensive disease. High-dose melphalan therapy for metastatic colon carcinoma, when used with autologous bone marrow transplantation, appears to achieve a high response rate with tolerable toxicity. Further investigation is needed to define the role of this therapy in the care of advanced colon carcinoma.

Adult↗
PubMed1985

Quantification of unscheduled DNA synthesis in mononuclear leukocytes of the horse.

This study compares the relationship between N-acetoxy-2-acetylaminofluorene (NA-AAF) and u.v. induced unscheduled DNA synthesis (UDS) and their respective relationships to age and blood pressure in horse mononuclear leukocytes with earlier, similar investigations on human leukocytes. U.v. induced UDS was found to proceed more rapidly than NA-AAF induced UDS. A pronounced lag period associated with the rapid demand for 3H-dThd into DNA after u.v. damage was observed. NA-AAF induced UDS correlated significantly with NA-AAF binding, age and the blood pressure of male horses. UDS values, induced by either method, were about half the level calculated for human leukocytes.

Acetoxyacetylaminofluorene↗
PubMed1985

gamma-Glutamyltransferase from Marthasterias glacialis: purification procedures and enzyme characterisation.

gamma-Glutamyl transferase has been purified 239-fold from the pyloric caeca of Marthasterias glacialis. It has a mol. wt. of 229,000. The pH optima for the hydrolysis and transfer reactions are 5.0 and 9.2. Novel purification procedures using hydroxyhexyl and aminohexyl derivatives of Sepharose 4B are described. The enzyme was bound by immobilised m-aminophenylboronic acid but not by immobilized concanavalin A.

Animals↗
PubMed1984

Audit of surgical practice in a community hospital.

The results of a prospective analysis of one year's surgery on inpatients in a busy community hospital showed that a high quality of surgery may be achieved with safety and low rates of complications. The results of a retrospective analysis of certain aspects of surgery was just as encouraging. Surgery that is performed in a community hospital is convenient for the patient, provides continuity of care by the general practitioner, and waiting list times are short. Surgical facilities can form an integral part of the comprehensive service provided by a community hospital and can lighten the caseload for minor surgery at the district general hospital. Close liaison between the two hospitals is essential.

Anesthesia↗
PubMed1982

The free-rider principle, the charity market and the economics of blood.

This article summarizes some recent developments in the economics of the charity market, presents some applications of the analyses and highlights areas which need interdisciplinary research. A brief summary of the fairly recent extension of economic analyses to non-private market institutions is presented, followed by an overview of economic analysis applied to the charity market, interspersed with examples of policy applications. The article concludes with a generalized application of economic analyses to the policy debates on the roles of the volunteer and commercial blood procurement systems in the United States.

Blood Banks↗