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Biomedical subjects

J M Thomas

Publications and source records attributed to J M Thomas.

At least 253 records · Page 14Linked to original sources
PubMed1991

Persistent reduction of B virus (Herpesvirus simiae) seropositivity in rhesus macaques acquired for a study of renal allograft tolerance.

One hundred and two rhesus macaques were used in a study of renal allograft tolerance. Each animal was monitored serologically more than one time to determine its B virus (Herpesvirus simiae) antibody status. The follow-up period for some individuals was 3 years, extending from 1986 to 1989. The accumulated test results eventually provided an opportunity to retrospectively support a contention that a small research colony of rhesus macaques could become and remain B virus seronegative if the animals were housed individually, monitored periodically, acquired only if they were seronegative, and culled if they converted to positive status. It was also possible that the test results might disclose useful information about the influence of acute immunosuppression on the reliability of determining B virus antibody status by serologic methods, and help formulate guidelines for selecting donor-recipient pairs. A review of the serologic test results disclosed that antibody status before the initiation of experimental therapy, and subsequent seroreactivity, did not change throughout the experimental lifetime of 92 monkeys. The few exceptions were six juveniles that lost detectable antibody, and four other juveniles that converted to positive. Preliminary data suggested that total lymphoid irradiation (TLI) and splenectomy were associated with the loss of detectable antibody; however, further study is needed to establish the validity and significance of this association. No other unexpected or unexplained results were associated with concomitant periods of acute immunosuppression. The number of seropositive animals in the colony was reduced to three through attrition and culling by the end of 1989.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Perineal, vulval and vaginoperineal reconstruction using the rectus abdominis myocutaneous flap.

Poor perineal healing is a major complication of total or partial pelvic exenteration especially when the pelvis and perineum have previously been irradiated. Perineal, vulval or vaginoperineal reconstruction was performed in five women using the inferiorly based rectus abdominis myocutaneous flap. Primary perineal wound healing occurred in all patients and no flap-related complications developed. Primary healing of abdominal wall wounds occurred in all patients without incisional hernia. Three of the patients had an anterior or total pelvic exenteration with continent urinary diversion by the Mitrofanoff technique. Two of the patients had complete vaginal reconstruction and one patient had after-loading catheters inserted for postoperative interstitial irradiation. The patients were in hospital for 42, 28, 21, 17 and 15 days respectively. The longest stays were associated with training for self-catheterization of the continent urinary diversion. Median follow-up was 9 months. One patient developed two perineal recurrences at 16 months which were resected, and she remains disease-free 6 months later.

Abdominal Muscles↗
PubMed1990

Hyperthermic isolated perfusion with melphalan in the treatment of advanced malignant melanoma of the lower limb.

A retrospective study of 91 patients with malignant melanoma treated by lower limb isolated hyperthermic regional perfusion was performed. Objective response in patients with evaluable disease was 78 per cent. The role of perfusion as primary treatment of large melanomas of the foot is confirmed and recommended. Control of locoregional disease and limb salvage remains a valuable and attainable therapeutic goal using this technique.

Chemotherapy, Cancer, Regional Perfusion↗
PubMed1990

Management of parotid metastases from cutaneous melanoma of the head and neck.

Parotid metastases from a cutaneous malignant melanoma are uncommon. Although the long-term prognosis is poor, loco-regional palliation is important. In a group of eight patients with parotid metastases, local control was obtained by superficial parotidectomy. Occult cervical lymph node metastases were identified in five cases in whom radical neck dissection provided regional control. Superficial parotidectomy with elective neck dissection is advocated for patients with parotid metastases from cutaneous melanoma to ensure optimal loco-regional palliation.

Adult↗
PubMed1990

Correlates of blood pressure in young insulin-dependent diabetics and their families.

We compared the correlates of blood pressure in 163 young patients with insulin-dependent diabetes and in 232 of their non-diabetic siblings. A single observer recorded blood pressure in all subjects, plus all their available parents, using a standardized technique. Other variables recorded included age, weight, height, presence of diabetes and urinary albumin. The major factors accounting for over 50% of the variance of systolic blood pressure (SBP) in both groups were age, weight, paternal SBP and sex. In addition, in the diabetic group the logarithm of the random urinary albumin concentration was a significant explanatory variable. For diastolic blood pressure (DBP) approximately 16% of the variance was explained by age, weight and maternal DBP. Parental blood pressure was an important determinant of blood pressure in both the diabetic and non-diabetic sibling groups. The similarity of the correlates of blood pressure in the two groups suggests that the determinants of blood pressure in young insulin-dependent diabetic patients and in the general population are similar.

Adolescent↗
PubMed1990

Decreased cyclic AMP degradation in NG 108-15 neuroblastoma X glioma hybrid cells and S49 lymphoma cells chronically treated with drugs that inhibit adenylate cyclase.

The increase in hormone-stimulated cyclic AMP accumulation observed in a variety of intact cells after chronic pretreatment with drugs that inhibit adenylate cyclase activity has been attributed to an increase in adenylate cyclase activity following withdrawal of the inhibitory drug. In NG 108-15 mouse neuroblastoma X rat glioma hybrid cells (NG cells) chronically treated with the muscarinic cholinergic agonist carbachol, we have found a significant decrease in the apparent degradation rate constant for cyclic AMP, in addition to an increase in the prostaglandin E1 (PGE1)-stimulated cyclic AMP synthesis rate in intact cells. In carbachol-pretreated NG cells that were stimulated with a maximally effective dose of PGE1, and that accumulated steady-state cyclic AMP concentrations fourfold or more higher than in control cells, the apparent rate constant for degradation was about 53% lower than the value for control cells. In carbachol-pretreated cells stimulated with a submaximal dose of PGE1 to yield a steady-state cyclic AMP concentration comparable to control cells, the apparent rate constant was 31% lower than the value for control cells. In S49 mouse lymphoma cells (S49 cells) chronically treated with an analog of the inhibitory agonist somatostatin, the first-order rate constant for cyclic AMP degradation in intact cells following isoproterenol stimulation was 29% lower than the value for control cells. Despite these changes in the kinetics of cyclic AMP degradation in intact NG cells and S49 cells, there was either no change or a minimal change (less than 10%) in phosphodiesterase activities assayed in extracts of cells chronically exposed to inhibitory drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-3-isobutylxanthine↗
PubMed1990

Silicone implant to prevent visceral damage during adjuvant radiotherapy for retroperitoneal sarcoma.

The incidence of local recurrence after surgery for retroperitoneal sarcoma is reduced by high-dose adjuvant radiotherapy but treatment is restricted by the effects of irradiation on adjacent viscera. By securing a silicone gel-filled implant (breast prosthesis) in the tumour bed after excision of the tumour, adjacent viscera are displaced from the site of maximum irradiation and may thereby be protected. We used this technique in three patients in whom excision of a retroperitoneal sarcoma was followed by high-dose adjuvant radiotherapy. Post-operative radiotherapy was well tolerated but local recurrence developed in one patient, and delayed perforation of the large bowel occurred in another. Both cases underwent further surgery at which the implant was removed. The same two cases also developed asymptomatic hydronephrosis on the side of the implant, attributed to local fibrosis.

Female↗
PubMed1990

Effects of alpha and beta adrenoceptor blocking drugs and ACE inhibitors on long term glucose and lipid control in hypertensive non-insulin dependent diabetics.

Long-term glycaemic control measured by glycosylated haemoglobin concentration was compared in hypertensive NIDD's taking placebo, alpha-blockers, beta-blockers (alone and in combination) and an ACE inhibitor (enalapril) each for 4 months. Alpha-blockade caused no deterioration in long-term glycaemic control in NIDD's. Beta-blockers caused a deterioration in glycaemic control in NIDD's (with some adverse effects on lipid profile). This was especially apparent with the lipophilic beta-blocker P. Concurrent use of an alpha-blocker with a beta-blocker prevents the deterioration due to beta-blockade. The ACE inhibitor, enalapril caused an improvement in long-term glycaemic control without alteration of lipid control in NIDD's.

Adrenergic alpha-Antagonists↗
PubMed1990

Formal axillary dissection.

Formal axillary dissection is a precise anatomical procedure by which the lymphatic contents of the axilla are removed en bloc. It is used as both a staging and a therapeutic procedure for carcinoma of the breast, and as a therapeutic or palliative procedure for established axillary metastases.

Axilla↗
PubMed1990

Prophylactic therapy for rejection after cardiac transplantation. A comparison of rabbit antithymocyte globulin and OKT3.

The value of prophylactic monoclonal or polyclonal antibody therapy early after cardiac transplantation is controversial. Between Jan. 1, 1987, and July 1, 1988, 32 consecutive patients underwent cardiac transplantation (cyclosporine, azathioprine, and prednisone maintenance therapy) with either early prophylactic rabbit antithymocyte globulin (n = 17) or monoclonal OKT3 (Ortho Diagnostic Systems, Inc., Raritan, N.J.) (10 days) (n = 15). Follow-up was through Sept. 1, 1988, for morbid events and through Jan. 1, 1989, for survival. All patients (100%) survived the study period (follow-up of 6 to 24 months). The efficacy of rabbit antithymocyte globulin and OKT3 prophylaxis was similar regarding median time (days) to first rejection (16 versus 21 days, p = 0.5), number of rejection episodes during first 2 months (1.5 versus 1.3 days, p = 0.8), and freedom from rejection at 2 months (18% versus 27%, p = 0.8). Early infections were slightly less common in the rabbit antithymocyte globulin group than the OKT3 group (median time to first infection: 318 versus 250 days, p = 0.5; freedom from rejection at 2 months: 82% versus 64%, p = 0.21), although differences were likely due to chance. Cytomegalovirus syndrome was common, with one case of cytomegalovirus pneumonia. T-cell markers during OKT3 treatment did not predict subsequent rejection (within 2 weeks after OKT3) as assessed by mean T3-lymphocyte count during OKT3 use (p = 0.3) or T3-lymphocyte count during the last 3 days of OKT3 use (p = 0.4). Inferences: (1) Prophylactic rabbit antithymocyte globulin or OKT3 with triple-drug immunosuppression yields excellent intermediate survival after heart transplantation. (2) These protocols for rabbit antithymocyte globulin and OKT3 provide similar protection against early rejection with a relatively low risk of early infection. (3) T-cell markers do not predict early rejection after OKT3.

Adult↗
PubMed1990

Activation of muscarinic cholinergic receptors in mouse neuroblastoma x rat glioma hybrid cells: rapid induction of enhanced capacity of prostaglandin E1 receptors to stimulate cyclic AMP accumulation.

Many cells develop an adaptive increase in the capacity of adenylate cyclase to synthesize cyclic AMP (cAMP) after prolonged (hours or days) exposure to drugs which initially inhibit enzyme activity. Recent evidence suggests that adaptive increases in cAMP responses can be induced within minutes by inhibitory drugs. We have investigated the kinetics for induction and decay of this phenomenon in mouse neuroblastoma x rat glioma hybrid cells. The muscarinic cholinergic agonist carbachol induced an increase in prostaglandin E1-stimulated cAMP accumulation within 2 min of pretreatment with carbachol; the increase was 70 to 100% above control values after exposure to carbachol for 30 min. Enhanced cAMP responsiveness decayed with a half-life of about 8 min after removal of carbachol. Pretreatment with carbachol for 30 hr led to an enhanced cAMP response which decayed in two components, a rapid component and an additional, more stable component which persisted for at least 2 hr after withdrawal of carbachol. Pertussis toxin prevented these effects of carbachol. Prevention of carbachol-induced inhibition of cAMP accumulation below basal concentrations with a phosphodiesterase inhibitor did not prevent the ability of carbachol to acutely induce augmented prostaglandin E1-stimulated cAMP accumulation. Mouse neuroblastoma x rat glioma hybrid cells exhibit an enhanced cAMP response after both acute and chronic exposure to a muscarinic cholinergic agonist although these processes decay with different time courses. The signal for this acutely induced adaptation does not appear to be the decrease in cellular cAMP concentration resulting from inhibition of adenylate cyclase but does require a pertussis toxin-sensitive substrate.

Adenylate Cyclase Toxin↗
PubMed1990

The daily variability of bronchial responsiveness to methacholine.

Ten mild atopic asthmatics on inhaled beta 2-agonists alone were studied in order to determine the repeatability of methacholine inhalation provocation tests at 24 h intervals over a period of 5 days. Such patients are most frequently studied in therapeutic trials of anti-asthmatic medications. There were no significant differences in results obtained on any of the days and no evidence for the development of tolerance to methacholine in this group of patients at one day intervals. The 95% confidence interval for repeatability of the results was +/- 1.05 doubling doses of methacholine, and 95% range +/- 2.36 doubling doses, comparable to the results obtained by other investigators on similar patients. Some investigators have produced more highly repeatable results but these have generally been obtained using highly selected groups of patients.

Adolescent↗