Biomedical subjects

R D Swinford

Publications and source records attributed to R D Swinford.

9 recordsLinked to original sources

PubMed1999

Changing patterns in the histopathology of idiopathic nephrotic syndrome in children.

BACKGROUND: It is widely accepted that minimal change nephrotic syndrome (MCNS) is the most common cause of nephrosis in children. Recent studies have demonstrated an increasing incidence of focal segmental glomerulosclerosis (FSGS) in adults. METHODS: To determine possible changes in the etiology of childhood nephrosis, the clinical charts of 152 pediatric patients diagnosed with idiopathic nephrotic syndrome between 1978 and 1997 were reviewed. Histopathological diagnosis was available in 105 patients. RESULTS: MCNS was present in 35% of all biopsies, whereas FSGS was observed in 31%. Even if we assume that all patients without a histological diagnosis had MCNS (presumptive MCNS), the total incidence of MCNS (biopsy proven + presumptive) in our population was only 55%. We observed a dramatic increase in the incidence of FSGS during recent years. Before 1990, FSGS was diagnosed in 23% of all renal biopsies but increased to 47% afterward (P = 0.02). This pattern was observed in all ethnic groups. In African Americans, there was a trend for an increase in the incidence of FSGS from 38% before 1990 to 69% after 1990. A similar trend was observed in Caucasians (from 20 to 45%) and Hispanics (from 8 to 33%) Hispanics had the highest incidence of MCNS (biopsy proven + presumptive: 73%), followed by Caucasians (53%) and African Americans (37%). The mean age for presentation of nephrotic syndrome in African Americans (8.0 +/- 0.9 years) was higher than in Caucasians (4.1 +/- 0.05) and Hispanics (3.3 +/- 0.5). CONCLUSIONS: Our study showed that the incidence of FSGS in children with idiopathic nephrotic syndrome has increased recently. Furthermore, in African American children. FSGS is the most common cause of nephrotic syndrome. These findings may have significant implications in the management of childhood nephrotic syndrome.

Adolescent↗

PubMed1998

Chronic rejection and chronic cyclosporin toxicity in renal allografts.

Recent evidence indicates that growth factors are critically important in both chronic rejection and chronic cyclosporin A toxicity, suggesting that these two entities share a common pathophysiological pathway, leading to progressive allograft failure. Here, Manuel Pascual and colleagues discuss the relevance of growth factors to chronic allograft nephropathy, and the implications for therapy in view of the great choice of immunosuppressive drugs now available.

Animals↗

PubMed1997

Dialysis membrane adsorption during CRRT.

Experimental and clinical studies have suggested that dialysis membrane biocompatibility may influence the morbidity and mortality of patients with acute renal failure. Complement activation by dialysis membranes may also prolong the recovery from acute renal failure. In this article, we review the concept of dialysis membrane adsorption, with particular attention to adsorption/inhibition of factor D, a highly specific serine protease of the alternative pathway of complement. The adsorptive properties of some dialysis membranes may be useful during continuous renal replacement therapies (CRRT) in critically ill patients.

Acute Kidney Injury↗

PubMed1997

Acute renal failure: role of dialysis membrane biocompatibility.

Recent clinical studies of acute renal failure in adults have focused attention on the biocompatibility of the dialysis membrane as a possible factor influencing patient morbidity and mortality. In this article, we review the concept of dialysis membrane biocompatibility and highlight the difficulty of finding an ideal definition. We then expand on the possible roles of complement and neutrophil activation by dialysis membranes, which may prolong the recovery from acute renal failure. The results of several clinical studies analyzing the impact of dialysis membranes on the course and outcome of acute renal failure are discussed. Finally, the possible relevance of biocompatibility in continuous renal replacement therapies is emphasized.

Adult↗

PubMed1991

Acute effects of delayed reperfusion on myocardial infarct shape and left ventricular volume: a potential mechanism of additional benefits from thrombolytic therapy.

The purpose of this study was to characterize the effects of late reperfusion on myocardial infarct shape and to quantitate associated changes in left ventricular volume. Reperfusion was delayed until there was no salvage of ischemic myocardium. Dogs underwent 6.5 h of left anterior descending coronary artery occlusion (n = 5) or 5.5 h of occlusion and 1 h of reperfusion (n = 5). Infarct shape was measured with pairs of ultrasonic crystals implanted circumferentially in the mid myocardium. Infarct stiffness was determined from end-diastolic pressure-segment length curves produced by aortic clamping. Left ventricular volume was measured with three pairs of endocardial ultrasonic crystals and the effect of infarct shape change on left ventricular volume was determined. Infarct size, expressed as a percent of the area at risk, was similar in reperfused (97 +/- 1%) and nonreperfused (98 +/- 1%) hearts. After coronary artery occlusion, infarct segments became akinetic and functional dilation, measured as end-diastolic ultrasonic crystal separation, increased to a similar extent in reperfused (24 +/- 7%) and nonreperfused (19 +/- 3%) hearts. In 13 additional dogs that underwent reperfusion and instrumentation with endocardial ultrasonic crystals for volume measurement, left ventricular volume increased 42 +/- 6% over the preocclusion level (p less than 0.001). Within minutes of reperfusion, the infarct stiffened, infarct dilation decreased to 1 +/- 4% over the baseline preocclusion level (p less than 0.05 vs. prereperfusion) and left ventricular volume decreased to 16 +/- 11% over the baseline level (p less than 0.01 vs. postocclusion). Thus, coronary artery reperfusion reverses initial infarct dilation. Changes in infarct dilation occur immediately after reperfusion and are accompanied by infarct stiffening and a decrease in left ventricular volume. Reperfusion can affect infarct shape and stiffness at a point in time when myocardial salvage is no longer possible.

Animals↗

PubMed1989

Regional left ventricular filling: does it reflect diastolic abnormalities in contiguous areas of myocardium?

To test the hypothesis that regional left ventricular filling reflects diastolic changes in contiguous areas of myocardium, we performed radionuclide ventriculograms on normal subjects, patients with left anterior descending coronary artery disease, and patients with anteroseptal myocardial infarctions. We reasoned that because diastolic properties of the anteroseptal myocardium should be different in the three groups of patients, regional filling in the anteroseptal area of the left ventricle should also be different, if regional filling does, indeed, reflect diastolic changes in the adjacent myocardium. While anteroseptal regional filling in the normal subjects was different than regional filling in the two patient groups, the degree of filling abnormality was similar in patients with and without myocardial infarctions. Our results suggest that regional left ventricular filling is not exclusively determined by diastolic changes in contiguous areas of myocardium.

Coronary Disease↗

PubMed1988

Effect of coronary artery bypass grafting on left ventricular diastolic function.

Because left ventricular (LV) diastolic function is abnormal in patients with coronary artery disease (CAD), pulsed Doppler echocardiography was used to evaluate LV filling before and after coronary artery bypass grafting (CABG). Filling was evaluated by Doppler in 2 studies: (1) in a group of 41 unpaired patients (11 with angiographically normal coronary arteries, 14 with CAD but without CABG and 16 at 1 week after CABG) and (2) in a group of 12 patients with CAD before and 1 week after CABG. Doppler sampling at the level of the mitral anulus was analyzed for the deceleration half-time and for the ratio of peak late (A) to peak early (E) filling velocity, measures reflecting early ventricular filling and the relative contribution of atrial contraction to ventricular filling. In the first study the deceleration half-time was significantly prolonged in both CAD and CABG groups. The late to early peak transmitral velocity ratio, however, was significantly prolonged only in the nonrevascularized CAD patients. In the second group of CAD patients studied before and 1 week after surgical revascularization, both the late to early peak transmitral velocity ratio and the deceleration half-time showed significant postoperative improvement. Thus, patients with CAD showed impairment in early LV filling and a compensatory increase in the proportion of filling with active atrial contraction. Successful CABG appears to result in normalization of early filling and decreased reliance on active atrial transport.

Coronary Angiography↗

PubMed1986

A new use for M-mode echocardiography in detecting left ventricular diastolic dysfunction in coronary artery disease.

Regional left ventricular (LV) diastolic function affects the global rate and pattern of LV filling. These changes may be detected by changes in the magnitude and timing of the increase in LV basal diameter during diastole. Because M-mode echocardiography possesses the high temporal and spatial resolution to detect such abnormalities, a group of 8 normal control subjects were compared with a group of 12 patients with coronary artery disease (CAD) to determine differences in the rate and timing of ventricular filling. The CAD patients had lower rates of fast filling expansion than the control subjects. The proportion of LV diastolic expansion during fast filling was lower. During atrial systole the increased rate of LV expansion was not significantly higher in the CAD patients, but the proportion of diastolic expansion occurring with atrial systole was increased. These changes may reflect a decrease in the rate and magnitude of early diastolic filling in the noncompliant ventricle and an increased reliance on active atrial transport. Thus, CAD alters the rate and pattern of LV filling. Changes in LV diameter as measured by M-mode echocardiography may be useful in detecting altered patterns of LV diastolic filling and identifying patients with CAD.

Adult↗

PubMedDate not supplied

Rapid activation of the alternative pathway of complement by extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is an effective therapy for patients with severe respiratory distress syndromes. However, an inflammatory response has been observed with the use of this therapy. We measured complement activation in vivo in two adults receiving ECMO for acute respiratory distress syndrome (ARDS). Production of complement activation fragments C4d, Bb, iC3b, and SC5b-9 was determined using commercial ELISA kits. In both patients there was intense activation of complement that peaked 1 hour (mean SC5b-9 increase to 1135% of baseline) after the start of ECMO and occurred predominantly via the alternative pathway (Bb production). Early and acute complement activation may be responsible for the initiation of the inflammatory response that has been observed in patients treated with ECMO.

Adult↗