Glucose repression of fbp1 transcription of Schizosaccharomyces pombe is partially regulated by adenylate cyclase activation by a G protein alpha subunit encoded by gpa2 (git8).

In the fission yeast Schizosaccharomyces pombe, genetic studies have identified genes that are required for glucose repression of fbp1 transcription. The git2 gene, also known as cyr1, encodes adenylate cyclase. Adenylate cyclase converts ATP into the second messenger cAMP as part of many eukaryotic signal transduction pathways. The git1, git3, git5, git7, git8 and git10 genes act upstream of adenylate cyclase, presumably encoding an adenylate cyclase activation pathway. In mammalian cells, adenylate cyclase enzymatic activity is regulated by heterotrimeric guanine nucleotide-binding proteins (G proteins). In the budding yeast Saccharomyces cerevisiae, adenylate cyclase enzymatic activity is regulated by monomeric, guanine nucleotide-binding Ras proteins. We show here that git8 is identical to the gpa2 gene that encodes a protein homologous to the alpha subunit of a G protein. Mutations in two additional genes, git3 and git5 are suppressed by gpa2+ in high copy number. Furthermore, a mutation in either git3 or git5 has an additive effect in strains deleted for gpa2 (git8), as it significantly increases expression of an fbp1-lacZ reporter gene. Therefore, git3 and git5 appear to act either in concert with or independently from gpa2 (git8) to regulate adenylate cyclase activity.

Dose-response study of intravenous torsemide in congestive heart failure.

In a double-blind dose-response study, 49 patients with New York Heart Association functional class III or IV heart failure were randomized to receive a single intravenous dose of 5, 10, or 20 mg torsemide or 40 mg furosemide. Torsemide produced dose-related decreases in body weight and increases in sodium and chloride excretion and urine volume. With the 20 mg dose of torsemide and the 40 mg dose of furosemide, body weight decreased significantly relative to baseline, and total and fractional 24-hour urinary excretion of sodium, chloride, and potassium and urine volume increased significantly. The 10 mg torsemide dose also produced a significant increase in urine volume. The results indicate that intravenous torsemide is effective for the acute treatment of sodium and fluid retention resulting from moderate to severe congestive heart failure.

Cloning and manipulation of the Schizosaccharomyces pombe his7+ gene as a new selectable marker for molecular genetic studies.

We have cloned the his7+ gene of the fission yeast Schizosaccharomyces pombe by complementation of the recessive mutant allele his7-366. The his7+ gene is able to complement a mutation of the Escherichia coli hisI gene, suggesting that his7+ encodes a phosphoribosyl-AMP cyclohydrase. Subcloning experiments localize the gene to a 1.9-kb XbaI-BglII fragment. We describe the construction of plasmids to facilitate the use of his7+ as a selectable marker in S. pombe studies. Plasmid pEA2 carries his7+ cloned into the pUC18 polylinker. From either pEA2 or the original his7+ clone, pMN1, fragments carrying his7+ can be isolated using a variety of restriction enzymes for the construction of gene disruptions. Plasmid pEA500 is a cloning vector that carries his7+ and ars1, yet retains the ability to use the blue/white color screen to identify recombinants.

Percutaneous valvuloplasty in a patient with mitral stenosis following surgical annuloplasty.

A case is described in which a patient with a Carpentier-Edwards annuloplasty ring developed mitral stenosis and was treated with percutaneous mitral valvuloplasty. Possible mechanisms for the development of mitral stenosis are briefly discussed.

The M-Heart percutaneous balloon mitral Valvuloplasty Registry: initial results and early follow-up. The M-Heart Group.

The initial results, complications and early follow-up of 74 patients undergoing percutaneous balloon mitral valvuloplasty in seven hospitals participating in a multicenter registry are reported. Seventy-four patients with a mean age of 53 years had 75 valvuloplasty procedures performed over a 2.5 year period. Eighty-nine percent of the attempted procedures were completed and resulted in an increase in mean mitral valve area from 1.0 +/- 0.04 to 2.0 +/- 0.1 cm2 (p less than 0.0001); the valve area increased greater than or equal to 50% of the baseline valve area in 73% of the patients. Major complications included procedure-related death (2.7%), cardiac tamponade (6.7%), systemic embolism (2.7%) and emergency surgery (6.7%). At a mean follow-up period of 14.6 months, the condition of the majority of patients had improved, and 89% of 55 patients treated only with valvuloplasty were in New York Heart Association functional class I or II. Thus, hemodynamic and clinical improvement can be obtained in the majority of patients with mitral stenosis treated with balloon valvuloplasty in multiple centers. However, suboptimal results and major complications occurred in a significant number of patients and may limit this procedure to use by experienced operators in hospitals with facilities for cardiac surgery.

Intravenous streptokinase in acute myocardial infarction.

Intravenous (IV) fibrinolytic therapy, a recent area of research, has a great deal of applicability in emergency medicine. We report our experience with 30 patients treated with this method. Thirty consecutive patients in the early stages of acute evolving myocardial infarction (AMI) were assigned to receive high-dose IV streptokinase, 1.5 million units over a 30-minute period. Patients presented to the treating hospital at a mean time of 1.21 +/- 1.08 hours, and treatment commenced at a mean time of 2.77 +/- 1.31 hours after the onset of symptoms. Using standard clinical criteria, 86.7% (n = 26) of the patients reperfused initially. Two, however, reoccluded within the first 48 hours, and their clinical symptoms of myocardial infarction reappeared. By clinical observation 80% (n = 24) of the patients reperfused, and myocardial salvage was observed. Twenty-four patients with clinical reperfusion and one additional patient had patency of the affected artery, yielding a reperfusion rate of 83.3% (n = 25) as judged by angiography within one week of AMI. Both patients who had reoccluded clinically also were found to be occluded on angiography. Clinical and angiographic methods yield very similar results for the judgment of reperfusion (80% vs 83%, respectively, with no significant difference, P not significant). The results of our study tend to confirm the efficacy of IV streptokinase as a valuable management tool for early myocardial infarction.

Myocardial infarction management with peripheral streptokinase.

The early management of myocardial infarction (MI) is undergoing a new evolution. Aggressive treatment and new invasive modalities have brought improved prognosis to these patients. Intracoronary administration of fibrinolytic agents is rapidly gaining wide acceptance. We report a pilot protocol for administration of peripheral intravenous (IV) versus direct intracoronary fibrinolytic agents in acute MI. Thirty patients with acute evolving MI were assigned consecutively to receive fibrinolytic therapy; 15 patients received intracoronary streptokinase and 15 received peripheral IV streptokinase at a dosage of 1.5 million units over a 30-minute period. Evaluation by clinical symptoms, ECG changes, and hemodynamic studies by angiography and radionuclide ventriculography indicated comparable and beneficial results for both groups. Patients assigned to the IV therapy were able to receive streptokinase therapy 1.5 hours earlier than those receiving intracoronary therapy, and they had a higher incidence of reperfusion. We conclude that IV streptokinase therapy may be preferable to intracoronary therapy in view of a higher reperfusion frequency, fewer complications, and greater ease of administration. With both treatment modalities, comparable improvement in left ventricular function was noted. Institutions that do not have invasive techniques available may well be the first to benefit from this method of myocardial salvage, and we encourage cooperation between emergency and cardiology departments.

Effects of intravenous glucose during pacing-induced angina pectoris in patients with coronary artery disease.

The effects of hypertonic glucose infusion on the anginal threshold determined by atrial pacing was studied in 14 patients with significant coronary artery disease. After glucose, angina occurred at a significantly lower heart rate and double product (systolic arterial pressure x heart rate), suggesting a decreased tolerance to ischemic stress. No stoichiometric relationship was noted between glucose uptake and lactate production, and there was no evidence that hypertonic glucose infusion resulted in enhanced anaerobic glycolysis in the ischemic myocardium. Acute elevation of plasma glucose levels may not be beneficial to patients with coronary artery disease.