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D R Singer

Publications and source records attributed to D R Singer.

67 records · Page 4Linked to original sources
PubMed1987

Secretion of atrial natriuretic peptide from the heart in man.

Plasma concentrations of atrial natriuretic peptide were measured in eight patients undergoing elective cardiac catheterisation and angiography. All patients had normal resting pressures in the cardiac chambers and no clinical evidence of heart failure. Plasma atrial natriuretic peptide rose significantly from the superior vena cava into the right atrium and right ventricle. The increase into the right atrium was variable, with no increase in three subjects, but there was a consistent increase in all subjects from the superior vena cava to to the right ventricle. These findings in the right atrium are probably caused by inadequate mixing and streaming of blood from the coronary sinus containing high concentrations of atrial natriuretic peptide. There was no increase in the concentration of natriuretic peptide from the pulmonary artery to the left ventricle, but the concentrations in the left ventricle were significantly higher than in the superior vena cava. These findings demonstrate that the heart secretes atrial natriuretic peptides in the absence of cardiac failure. Studies based on sampling of the right atrium will not accurately measure cardiac secretion of atrial natriuretic peptide and will therefore be likely to obscure the mechanisms responsible for regulating its secretion. The right ventricle and pulmonary artery are the best sampling sites to measure atrial natriuretic peptide release from the right atrium.

Aged↗
PubMed1987

Captopril and nifedipine in combination for moderate to severe essential hypertension.

The effects of the addition of a calcium entry antagonist, nifedipine (20-mg tablet twice a day), to an angiotensin converting enzyme inhibitor, captopril (25 mg three times a day), and the addition of captopril to nifedipine were observed in two separate studies in patients with essential hypertension. After 4 weeks of captopril therapy alone, mean arterial pressure fell by 12 mm Hg, and with the addition of nifedipine to captopril for a further month, blood pressure fell by an additional 10 mm Hg. In a separate group of patients treated with the same doses, mean arterial pressure fell by 17 mm Hg with nifedipine treatment alone; when captopril was added to the nifedipine therapy for an additional month, mean arterial pressure fell by a further 11 mm Hg. These blood pressures were measured 2 hours after the last dose; however, there was less of a fall in blood pressure when it was measured 12 hours after the last dose. This study confirms that captopril and nifedipine have a marked additive effect on blood pressure in whichever order they are given, but it shows that the combination is relatively short-acting.

Adult↗
PubMed1987

Nifedipine and acebutolol in combination for the treatment of moderate to severe essential hypertension.

In a randomised, crossover study of patients with moderate to severe essential hypertension, the effects of the calcium entry antagonist nifedipine and the beta-receptor blocking drug acebutolol were studied on their own, and in combination. After 4 weeks of nifedipine tablets 20 mg twice daily (Adalat, Bayer), mean supine blood pressure (BP) fell by 20 mmHg and after 4 weeks of acebutolol 200 mg twice a day (Sectral, May & Baker) by 11 mmHg. When nifedipine and acebutolol were given in combination in the above doses for 4 weeks, there was a significantly greater fall in BP than with either agent alone, supine mean arterial pressure falling by 27 mmHg. The above BPs were measured 2 h after the last dose of tablets. Measurements 12 h after the last dose showed smaller falls in BP, with a significantly greater fall with combination treatment than with acebutolol alone. The fall in BP 12 h after the last dose of the combination was greater than with nifedipine alone but this difference was not statistically significant. This randomised, controlled study showed that nifedipine and acebutolol have a marked additive effect on BP which is sustained for at least 12 h after treatment.

Acebutolol↗
PubMed1986

Raised concentrations of plasma atrial natriuretic peptides in cardiac transplant recipients.

Plasma atrial natriuretic peptide concentrations were measured by radioimmunoassay six to 77 weeks after operation in eight cardiac transplant recipients with no appreciable evidence of cardiac failure or rejection and in eight control subjects matched for age, sex, race, and blood pressure. Plasma atrial natriuretic peptide concentrations were significantly higher in the cardiac transplant recipients (mean 19.4 (SE 3.9) ng/l) than in the controls (7.3 (1.2) ng/l p less than 0.01). The mechanisms underlying these raised values were not clear. These findings suggest that the transplanted atria may secrete atrial peptides and also that innervation is not obligatory for secretion of atrial natriuretic peptides to occur. Before this can be confirmed, however, it remains to be established what the relative contribution of donor and recipient atrial tissue is to the secretion of these peptides.

Adult↗
PubMed1986

Cryoglobulinaemia: clinical features and response to treatment.

We report the clinical features and outcome of 16 patients with cryoglobulinaemia. Two patients with Type I cryoglobulinaemia both had IgG kappa monoclonal paraproteins. Nine of 10 with Type II disease had monoclonal IgM kappa and polyclonal IgG; one had monoclonal IgG kappa and polyclonal IgG in the cryoglobulin. Underlying disorders identified in 3 of the 4 Type III patients were Sjogren's syndrome, infective endocarditis, and non-A non-B hepatitis and HTLV III infection. The commonest presenting features were rash in 94 p. 100 (ulceration 25 p. 100), arthralgia in 63 p. 100 (erosive arthritis 32 p. 100), renal disease in 63 p. 100, neurological involvement in 56 p. 100, hepatomegaly in 32 p. 100 and splenomegaly in 32 p. 100. Major associated conditions were progressive bronchiectasis in one case, and severe peripheral vascular disease in another; underlying malignancy was found in 2 cases (lymphoma and malignant melanoma). Treatment was with plasma exchange (PE) and immunosuppressive drugs (ID) in 10, PE alone in 3, ID alone in 2 and antibiotics [corrected] in 1. Fourteen of 16 patients showed an initial clinical response and fall in cryoglobulin levels. Four patients have died, one each from gastro-intestinal haemorrhage, sepsis, pulmonary embolism and lymphoma. Of the remaining 12 patients, all are symptomatically controlled and 10 have persisting cryoglobulinaemia (3 on PE and ID, 2 on PE, 2 on ID and 3 on no treatment). Of the two cases in whom cryoglobulinaemia resolved, one (Type II) had received PE and ID and the other (Type III) had been treated with antibiotics and surgery for infective endocarditis.

Adult↗
PubMed1986

Renal impairment in sarcoidosis: granulomatous nephritis as an isolated cause (two case reports and review of the literature).

Renal impairment in sarcoidosis is unusual: cases with granulomatous interstitial nephritis (GIN) and without associated glomerular disease, nephrocalcinosis and hypercalcemia have rarely been described. We report 2 such cases, one of whom is the first patient documented as surviving following presentation in dialysis dependent renal failure. Review of the literature revealed a further 20 patients. Of the 22 patients, including our own, 3 failed to respond to treatment, all dying in acute renal failure. Relapse occurred in 4, in association with rapid reduction or early cessation of treatment. No relapse was reported later than 9 months after starting treatment with corticosteroid. The majority of patients (15/19) who responded to treatment had residual renal impairment after up to 30 months of steroid treatment.

Adult↗
PubMed1983

Lymphangioma of kidney.

Lymphangioma of kidney is a rare, symptomatic but benign tumour. A case is reported and the literature reviewed. Aetiology and its effect on the incidence, non-invasive investigation, treatment and pathology are discussed.

Aged↗