Effects of fine particulate matter and its constituents on childhood pneumonia: a cross-sectional study in six Chinese cities

Background

Evidence of the effects of fine particulate matter (PM_2·5) and its chemical constituents on childhood pneumonia is scarce. We aimed to investigate the effects of PM_2·5 and its chemical constituents on doctor-diagnosed pneumonia in preschool children in China.

Surgical approach for patients with unstable angina pectoris: role of the response to initial medical therapy and intraaortic balloon pumping in perioperative complications after aortocoronary bypass grafting.

The role of the response to initial medical therapy and intraaortic balloon pumping in perioperative complications was evaluated in 194 consecutive patients with unstable angina pectoris who underwent cardiac catheterization and coronary surgery from July 1975 through December 1977. Sixty-four patients (33 percent) responded to medical therapy within 48 hours after the initiation of full medical therapy in the coronary care unit and underwent elective cardiac catheterization and coronary surgery; 130 patients (67 percent) did not respond to medical therapy. Of these 130 patients, 75 (58 percent) received the preoperative assistance of an intraaortic balloon pump and underwent emergency cardiac catheterization and surgery. Fifty-five patients (42 percent) of the medical non-responders were not treated with an intraaortic pump and underwent emergency cardiac catheterization and surgery. Chi square analysis revealed that the clinical characteristics of the patients in all three groups were similar.The overall rate of operative mortality was 6.1 percent. Medical responders had no operative mortality, medical nonresponders with intraaortic balloon pumping had an operative mortality rate of 5.3 percent and medical nonresponders without balloon pumping a rate of 14.5 percent. The overall incidence rate of perioperative myocardial infarction was 13 percent; it was 6 percent in medical responders, 6.6 percent in nonresponders with intraaortic balloon pumping and 29 percent in non-responders without intraaortic balloon pumping. Thus, this study suggests that perioperative complications can be minimized by initial aggressive medical therapy. If this therapy fails, intraaortic balloon counterpulsation can produce a reduction in perioperative complications similar to that produced by medical therapy.     

Management of hypercholesterolemia: evaluation of practical clinical approaches in healthy young adults.

A work site-located clinic screened 6,000 employees (91 percent participation) and identified 146 hypercholesterolemic subjects (100 percent initial participation, 12 percent subsequent dropout rate). The subjects, aged 20 to 50 years, were randomly classified into four groups: Group A, treatment in a lipid intervention clinic with diet for 6 weeks, then diet plus clofibrate for the subsequent 18 weeks; Group B, diet treatment from a clinic nutritionist with the cooperation of the subject's private physician; Group C, referral for treatment by a private physician; and Group D, no intervention. Initial mean cholesterol was 294 mg/100 ml. At 24 weeks, all intervention groups had decreases in serum cholesterol (Group A, 12 percent; Group B, 15 percent; Group C, 17 percent; P less than 0.001). The control group (D) had a small decrease in cholesterol (4 percent). Decreases in cholesterol were correlated with weight loss and decrease in fasting serum triglycerides but not with the use of clofibrate. Serum cholesterol can be reduced in healthy young adults by several practical methods.     

Effects of oral mexiletine on left and right ventricular function

Malignant ventricular arrhythmias often occur in patients with left ventricular (LV) dysfunction. Antiarrhythmic drugs may further impair LV function in these patients. Mexiletine, a lidocaine congener, is an effective antiarrhythmic drug, but when administered orally, its effect on LV and right ventricular (RV) function is unknown. To determine the hemodynamic effects of mexiletine, LV and RV ejection fraction (EF) were measured by radionuclide ventriculography in 10 patients with LV dysfunction (LVEF less than 50%). Symptom-limited exercise tests were also performed. Patients were studied before and during therapy with oral mexiletine. There was no significant change in LVEF (28% vs 27%) or RVEF (46% vs 41%). Also, heart rate at rest, exercise duration and peak heart rate during exercise were unchanged. Thus, in patients with LV dysfunction, oral mexiletine does not significantly affect LV or RV function.     

Acute hemodynamic effect of oral nifedipine in severe chronic congestive heart failure

The temporal hemodynamic effects of oral nifedipine after a single dose of 20 to 40 mg were evaluated in 11 patients with severe chronic congestive heart failure (left ventricular ejection fraction 0.22 +/- 0.7 [mean +/- standard deviation]). Nifedipine significantly reduced systemic vascular resistance, from 1,850 +/- 493 to 1,315 +/- 398 dynes s cm-5 at 1 hour (29%), to 1,410 +/- 246 at 3 hours and to 1,523 +/- 286 at 6 hours (p less than 0.05). Cardiac index increased 21%, from 2.07 +/- 0.46 to 2.51 +/- 0.83 liters/min/m2 at 1 hour, to 2.38 +/- 0.53 liters/min/m2 at 3 hours (p less than 0.05) and to 2.24 +/- 0.41 liters/min/m2 at 6 hours. The group response of stroke volume to nifedipine was smaller. A peak increase of 17% was seen 3 hours after initiation of therapy (22.6 +/- 7.2 versus 25.5 +/- 6.1 ml/m2). This difference did not reach statistical significance. Mean blood pressure declined significantly, from 94 +/- 20 to 80 +/- 13 mm Hg at 1 hour, to 83 +/- 15 mm Hg at 3 hours and to 86 +/- 17 mm Hg at 6 hours (p less than 0.05) and was associated with no significant change in heart rate. The marked decrease in blood pressure resulted in a decrease in rate-pressure product from 12,272 +/- 4,230 to 10,500 +/- 2,074 mm Hg/min at 1 hour, to 10,374 +/- 2,735 mm Hg/min at 3 hours and to 11,047 +/- 3,813 mm Hg/min at 6 hours (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Dopamine effects on the intestinal circulation.

The effects of intra-arterial infusion of dopamine on superior mesenteric artery blood flow, intestinal flow, intestinal oxygen consumption, and capillary density were studied in anesthetized dogs before and after blockade of dopamine receptors with haloperidol and after beta-adrenergic receptor blockade with propranolol. Mesenteric blood flow to a distal segment of the small intestine was measured with an electromagnetic blood flow-meter and intestinal oxygen consumption was calculated from the measured arteriovenous oxygen difference across the intestine and total blood flow. Intestinal capillary density was estimated from the clearance of 86Rb. In normal animals prior to dopaminergic or beta-adrenergic blockade, dopamine caused a dose-related decrease in mesenteric blood flow, intestinal oxygen consumption, and 86Rb clearance. Only the lowest dose of the drug, 1 mug/Kg.-min., did not significantly change the intestinal capillary density. In dogs pretreated with the dopamine receptor, antogonist, haloperidol, dopamine (20 mug/Kg.-min.) caused a significant increase in blood flow and oxygen consumption and did not significantly alter the number of perfused intestinal capillaries. These increases in haloperidol-blocked animals administered dopamine were reversed by propranolol. Our results indicate that dopamine caused smooth muscle contraction in mesenteric arterioles and precapillary sphincters, thereby producing intestinal ischemia and hypoxia. These findings with haloperidol and propranolol indicate that dopamine stimulates at least two different receptors in the canine mesenteric vascular bed: a constrictor receptor blocked by haloperidol and a dilator receptor blocked by propranolol.     

Gout with purine overproduction due to increased phosphoribosylpyrophosphate synthetase activity

Two brothers with marked purine overproduction and clinical gout showed activity of the enzyme phosphoribosylpyrophosphate (PP-ribose-P) synthetase in erythrocyte lysates 2.5 to 3.0-fold greater than that found in normal subjects or in other patients with gout. Associated with the increased activity of this enzyme, which catalyzes the synthesis of the regulatory substrate PP-ribose-P from adenosine triphosphate (ATP) and ribose-5-phosphate, was an increased intracellular PP-ribose-P concentration and an increased ability of intact erythrocytes to generate PP-ribose-P. In fibroblasts cultured from one of the affected brothers, these findings were confirmed, and an increased rate of the de novo purine biosynthetic pathway was demonstrated both in fibroblasts and in the affected brothers in vivo. The association of altered PP-ribose-P synthetase activity with increased intracellular PP-ribose-P generation and increased purine synthesis suggested that the proximal cause of the patients' gout was the increased enzyme activity.Hemolysates from a daughter of one of the affected brothers contained increased enzyme activity suggesting dominant hereditary transmission of the abnormality.The increased enzyme activity appeared to reside in the enzyme protein, although no evidence for a structural alteration in the patients' enzyme has thus far been found. Increased PP-ribose-P synthetase activity was apparent over a wide range of inorganic phosphate concentrations distinguishing the present abnormality from one previously described.Increased PP-ribose-P synthetase activity represents another hereditary enzyme aberration resulting in purine overproduction and clinical gout and demonstrates that human disease states can result from overabundance of enzyme activity as well as from deficiency.     

Correlates of reperfusion ventricular fibrillation in dogs

To elucidate determinants of reperfusion ventricular fibrillation (VF), regional myocardial blood flow, ATP, creatine phosphate (CP), heart rate and blood pressure were compared in 2 groups of anesthetized dogs: those that fibrillated spontaneously upon release of a 15-minute coronary artery occlusion (VF group, n = 8) and those that did not fibrillate when reperfused (No VF group, n = 27). Arterial pressure and heart rate before and during coronary artery occlusion were similar in both groups. Ischemie endo- and epicardial ATP values, measured at the end of the occlusion period, were reduced approximately 20% of nonischemic values in both groups. In contrast, CP (nmohmg protein^?1) within the ischemie zone was significantly lower in the VF group in both the epicardium (14.3 ± 1.6 in the VF group vs 22.8 ± 2.5 in the No VF group, p < 0.01) and the endocardium (9.0 ± 2.0 in the VF group vs 18.7 ± 1.8 in the No VF group, p < 0.01). Furthermore, epi- and endocardial regional myocardial blood flow in the center of the ischemic zone during occlusion was significantly lower in VF dogs than in No VF dogs. Epicardial flow was 0.06 ± 0.03 ml·min^?1·g^?1in VFdogsvs 0.44 ± 0.06 in No VF dogs (p < 0.001) and endocardial flow was 0.03 ± 0.02 ml·min^?1·g^?1 in VF dogs vs 0.23 ± 0.04 ·ml-min^?1·g^?1 in No VF dogs (p < 0.001). These data suggest that low levels of regional myocardial blood flow and CP during coronary artery occlusion are associated with an increased risk of VF on reperfusion. Thus, the severity of ischemia in the center of the ischemie zone may be a determinant of reperfusion VF.     

Radionuclide angiographic assessment of left ventricular function during exercise in patients with a severely reduced ejection fraction

To study the effect of exercise on left ventricular ejection fraction in patients with congestive cardiomyopathy and the relation of the response to the origin of the myocardial dysfunction, 30 patients with a severely reduced ejection fraction (30 percent or less) were evaluated with radionuclide angiography. Group I consisted of 16 patients with ischemic cardiomyopathy and a mean (± standard deviation) resting ejection fraction of 22.3 ± 6.1 percent. Group II was composed of 14 patients with primary cardiomyopathy and a mean resting ejection fraction of 19.3 ± 4.7 percent. The mean age, left ventricular end-diastolic pressure, cardiac index and resting left ventricular ejection fraction of Groups I and II were similar; however, the change in the ejection fraction during similar levels of exercise differed significantly. The mean exercise ejection fraction decreased to 16.7 ± 6.8 percent in Group I, but increased to 24.6 ± 6.4 percent in Group II (p < 0.001). Thus, exercise usually results in a directionally opposite change in left ventricular ejection fraction depending on the origin of the congestive cardiomyopathy.     

"Hairy cell" leukemia: a heterogeneous chronic lymphoproliferative disorder.

Thirteen patients with “hairy cell” leukemia and circulating tartrate-resistant acid phosphatase (TRAP)-positive mononuclear cells were studied. A high percentage of peripheral mononuclear cells from 12 patients were positive for surface membrane immunoglobulin (Smlg). Unlike studies in chronic lymphocytic leukemia, in most of these patients with “hairy cell” leukemia it was not possible to establish “clonality” on the basis of λ/κ or immunoglobulin-class cell surface markers because of frequent weak reactions with more than one antiserum in each group. Complement (C₃) receptor-bearing cells accounted for 69 per cent of the peripheral mononuclear cells in one patient. In another patient, 80 per cent of the peripheral mononuclear cells were positive for Fc receptors. Both patients also had high levels of Smlg-positive cells. In a third patient, peripheral mononuclear cells were of T-cell type as determined by over 80 per cent E rosetting and only 2 per cent Smlg-bearing cells. Phytohemagglutinin (PHA) stimulation on peripheral mononuclear cells from five patients revealed weak responses at three days. However, when this response was followed further, it reached normal intensity by five days of incubation, in contrast to cells from patients with chronic lymphocytic leukemia which gave a peak PHA response at eight to nine days. Cells from all patients, except cells from patients with T-cell type “hairy cell” leukemia, showed positive cytotoxic reactions with antiserums designating various B-cell (Merrit; la-like) alloantigenic groups. “Hairy-cell leukemia” appears to be a heterogeneous group of chronic lymphoproliferative disorders.