Search PubMed⌕ Search

Biomedical subjects

B Greenberg

Publications and source records attributed to B Greenberg.

204 records · Page 12Linked to original sources
PubMedDate not supplied

Cloning and sequence analysis of the cDNA for the rat atrial natriuretic factor precursor.

Atrial extracts contain factors which induce potent natriuresis changes in renal haemodynamics, and relax pre-contracted vascular smooth muscle. Low-molecular-weight peptides which mimic these actions have now been purified by several groups, including ours (see accompanying paper), and higher-molecular-weight proteins with similar but less potent biological activities have also been identified and are presumed to be precursors. If released into the circulation, these peptides, collectively called atrial natriuretic factor (ANF), may play a significant part in blood-pressure homeostasis, regulation of extracellular fluid volume and as antagonists to the hypertensive effects of the renin-angiotensin system and other hormonal and neurotransmitter systems. We describe here the isolation and characterization of rat atrial cDNA clones which encode ANF. Nucleotide sequence analysis shows that auriculin corresponds to the 25 amino acids located close to the C-terminus of a 152-amino acid ANF precursor. Analysis of the in vitro translation products of precursor ANF mRNA suggests that multiple forms of the precursor may exist.

Amino Acid Sequence↗
PubMedDate not supplied

Platinum in blood mononuclear cells from patients after cisplatin therapy.

The feasibility of monitoring cisplatin chemotherapy by measuring platinum (Pt) concentrations in blood mononuclear cells was tested in six patients (four with squamous cell carcinomas of the head and neck, one with non-Hodgkin's lymphoma, and one with lung carcinoma). Blood samples (20 to 40 mL) were collected at intervals from 6 min to 21 days after an iv infusion of cisplatin (80 or 100 mg per m2). Blood mononuclear cells were harvested on a Ficoll-Hypaque gradient, washed repeatedly, counted, and homogenized by sonication in 0.5 mL of saline solution. Pt was analyzed in duplicate 40 microL samples of plasma (N = 26) or cell homogenates (N = 23) by electrothermal atomic absorption spectrophotometry with Zeeman background correction. Immediately after the cisplatin infusion, plasma Pt concentrations averaged 2.6 (SD +/- 0.2) mg per L and mononuclear cell Pt concentrations averaged 2.5 +/- 0.5 ng per 10(6) cells. At 24 to 26 hr post-infusion, plasma Pt concentrations averaged 1.6 +/- 0.2 mg per L and mononuclear cell Pt concentrations averaged 2.3 +/- 0.6 ng per 10(6) cells. Plasma Pt disappearance followed two-compartment kinetics in all patients; the plasma Pt disappearance half-time (T1/2, mean +/- SD) was 148 +/- 41 hours. The Pt concentrations in blood mononuclear cells diminished gradually during the period of observation; the T1/2 could not be reliably determined, but was estimated to be longer than two weeks. This study shows that Pt can be measured in mononuclear cells of patients after cisplatin treatment and that Pt disappears more slowly from blood mononuclear cells than from plasma of these patients.

Adult↗
PubMedDate not supplied

Diagnosis and treatment of Prinzmetal's variant angina.

The presentation, diagnosis (including provocative testing), and therapy of Prinzmetal's variant angina are reviewed. Prinzmetal's variant angina (PVA) is a form of angina caused by coronary-artery vasospasm (CAS) and is not associated with exertion. It is diagnosed by history, electrocardiogram, or coronary-artery angiography. Provocative tests, such as the cold-pressor test or intravenous ergonovine maleate, are sometimes used to aid diagnosis of PVA. Nitrates, adrenergic - blocking agents, and calcium-channel blocking agents can be used in treating PVA. Nitroglycerin and isosorbide dinitrate effectively relieve CAS. However, long-term prospective studies on the use of these drugs for PVA are lacking in the literature. Studies on treating PVA with adrenergic-blocking agents have been equivocol, with some studies reporting improvement and some reporting worsening. Calcium-channel blocking agents are promising drugs for PVA. Nifedipine is generally considered the prototype of this class for antianginal activity. It is administered orally in PVA patients and is effective. Side effects are mild and do not usually require termination of therapy. Verapamil hydrochloride, the prototype calcium-channel blocking agent for arrhythmias, is effective for PVA, but only 10-20% of an orally administered dose reaches systemic circulation because of the first-pass effect. Other calcium-channel blockers, including perhexilene maleate, diltiazem hydrochloride, prenylamine, and lidoflazine, have been tested in a few CAS patients with some success; adverse effects and toxicities limit the use of some of them, especially perhexilene. Therapy, using combinations of nitrates, adrenergic-blocking agents, and calcium-channel blocking agents, is needed in some patients. Dosing guidelines for all drugs are given in the paper. Treatment of PVA should begin with oral nitrates. Calcium-channel blocking agents are indicated in the patient who has failed to respond or is intolerant to maximum doses of nitrates given in various forms.

Angina Pectoris, Variant↗