Effect of acute hypercapnia on alpha atrial natriuretic peptide, renin, angiotensin II, aldosterone, and vasopressin plasma levels in patients with COPD

Disturbances in hormonal systems involved in sodium and water homeostasis are common during respiratory insufficiency. To investigate the role of hypercapnia, we designed a study to examine the hormonal response to acute hypercapnia induced at constant cardiac filling pressures and without hypoxemia. Seven sedated patients with COPD receiving mechanical ventilation were studied during five successive periods. Hemodynamics, arterial blood gases, and plasma hormone levels (atrial natriuretic peptide, renin, angiotensin II, aldosterone, vasopressin) were measured three times during 60 min of acute hypercapnia (52 +/- 5 mm Hg) and at control periods, before (36 +/- 4 mm Hg) and after (42 +/- 3 mm Hg) acute hypercapnia. During acute hypercapnia, mean pulmonary arterial pressure and cardiac output were increased without variation of other measured cardiorespiratory data and hormonal levels when compared with control values. After acute hypercapnia, cardiorespiratory variables returned to control values without variations of hormonal levels. Our results show that moderate acute hypercapnia does not significantly influence the hormonal levels when cardiac filling pressures and sympathetic tone remain stable. We suggest that changes in those plasma hormones involved in salt and water homeostasis during acute hypercapnia are secondary to hemodynamic changes induced by acute respiratory failure and not to acute hypercapnia per se.     

Acute dacryocystic retention

Acute dacryocystic retention is a disease of adults under 50 years old due to a noninfective foreign body blocking the nasolacrimal duct. It is characterized by the sudden onset of severe unilateral facial pain without significant localized swelling or erythema. Palpation of the involved lacrimal sac reveals slight induration and marked tenderness. Percutaneous aspiration of lacrimal sac contents, followed by probing of the nasolacrimal duct, is usually curative.     

Effect on outcome of the presence or absence of chest pain at initiation of recombinant tissue plasminogen activator therapy in acute myocardial infarction. The Thrombolysis in Myocardial Infarction Investigators

To ascertain whether the outcome of patients with suspected myocardial infarction differs when chest pain is still present at initiation of thrombolytic therapy, participants in the Thrombolysis in Myocardial Infarction Phase II study, all of whom presented within 4 hours of symptoms onset, were retrospectively divided into 2 groups: (1) those with chest pain present at onset of intravenous thrombolysis, n = 3,000; and (2) those who were free of chest pain on beginning intravenous thrombolytic therapy, n = 337. Patients free of chest pain were older (58 vs 57 years, p = 0.01), more often women (23 vs 17%, p = 0.01), had fewer electrocardiographic leads with ST elevation (3.8 vs 4.1, p < 0.001), and the presenting event was confirmed less often as myocardial infarction than as chest pain without infarction (88 vs 96%, p < 0.001). There were no significant differences between the 2 groups for in-hospital death, reinfarction, recurrent ischemic events, stroke, overall hemorrhagic complications, coronary angioplasty or bypass surgery. At 6-weeks follow-up, more pain-free patients had resting ejection fraction > 0.55 (35 vs 31%, p = 0.001) and fewer developed congestive heart failure (12 vs 20%). At 1-year follow-up, fewer pain-free patients developed congestive heart failure (15 vs 21%, p = 0.009), but no differences existed between the 2 groups in frequency of death, reinfarction, coronary angioplasty, bypass surgery or anginal class. Thus, there are several observations in patients who were free of chest pain at onset of lytic therapy. (1) The majority developed enzymatic or electrocardiographic evidence of acute myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparative study of velocity measurements in major blood vessels using magnetic resonance imaging and Doppler ultrasound

Velocity measurements in major blood vessels were obtained in studies of volunteers using magnetic resonance imaging (MRI) and compared with Doppler ultrasound (US). The vessels studied were the abdominal aorta, superior mesenteric artery, common carotid artery, superficial femoral artery and middle cerebral artery. Using a paired t-test, no significant difference was found between velocity values estimated by MRI and US (p > 0.08). The relative advantages of each technique in radiological practice are discussed.     

Identification of HLA-A3 and -B7-restricted CTL response to hepatitis C virus in patients with acute and chronic hepatitis C

We investigated the role of the two highly conserved cysteine residues, cysteines 67 and 95, of the human immunodeficiency virus type 1 (HIV-1) protease in regulating the activity of that protease during viral maturation. To this end, we generated four HIV-1 molecular clones: the wild type, containing both cysteine residues; a protease mutant in which the cysteine at position 67 was replaced by an alanine (C67A); a C95A protease mutant; and a double mutant (C67A C95A). When immature virions were produced in the presence of an HIV-1 protease inhibitor, KNI-272, and the inhibitor was later removed, limited polyprotein processing was observed for wild-type virion preparations over a 20-h period. Treatment of immature wild-type virions with the reducing agent dithiothreitol considerably improved the rate and extent of Gag processing, suggesting that the protease is, in part, reversibly inactivated by oxidation of the cysteine residues. In support of this, C67A C95A virions processed Gag up to fivefold faster than wild-type virions in the absence of a reducing agent. Furthermore, oxidizing agents, such as H2O2 and diamide, inhibited Gag processing of wild-type virions, and this effect was dependent on the presence of cysteine 95. Electron microscopy revealed that a greater percentage of double-mutant virions than wild-type virions developed a mature-like morphology on removal of the inhibitor. These studies provide evidence that under normal culture conditions the cysteines of the HIV-1 protease are susceptible to oxidation during viral maturation, thus preventing immature virions from undergoing complete processing following their release. This is consistent with the cysteines being involved in the regulation of viral maturation in cells under oxidative stress.