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Biomedical subjects

A Kagan

Publications and source records attributed to A Kagan.

At least 37 records · Page 2Linked to original sources
PubMed1993

Heterogeneity in peritoneal transport during continuous ambulatory peritoneal dialysis and its impact on ultrafiltration, loss of macromolecules and plasma level of proteins, lipids and lipoproteins.

We investigated the effect of heterogeneity in the peritoneal transport of plasma proteins on dialysis efficiency and plasma levels of proteins, lipids and lipoproteins in 32 patients undergoing long-term continuous ambulatory peritoneal dialysis (CAPD; 9 females and 23 males, 18-76 years old). Eleven patients were studied on several occasions (at 0-42 months) and the remainder at 6-60 months on CAPD (n = 49). We have divided our patients arbitrarily into two equal groups according to their protein concentration in the peritoneal effluent at the end of an 8-hour cycle. Patients with a high peritoneal protein concentration (> or = 2 g/l/1.73 m2) have lower ultrafiltration capacity, higher glucose absorption rate and increased loss of most plasma proteins [including albumin, immunoglobulins (Ig), complement components and high-density lipoproteins (HDL)] compared to patients with a low peritoneal protein concentration (< 2 g/l/1.73 m2). Consequently, plasma levels of albumin, IgM and HDL were lower in patients with a high peritoneal protein concentration. The latter had also increased levels of plasma triglycerides and very-low-density lipoproteins. The difference observed in peritoneal transport between the groups could be ascribed only in part to the duration of CAPD treatment, and hence to the number of peritonitis episodes but not to medications. Therefore, we suggest that inherent constitutional factors may be responsible for some of the observed heterogeneity in the peritoneal transport of these patients which is already evident at the start of CAPD treatment. Patients with high peritoneal transport are exposed to an augmented atherogenic plasma lipid profile in addition to a reduction in dialysis efficiency (ultrafiltration failure). These patients may become prone also to nutritional and immunological disturbances. Therefore, we suggest taking these effects into consideration before choosing the appropriate dialysis modality in patients with increased peritoneal transport for plasma proteins.

Adolescent↗
PubMed1993

Serum concentrations and peritoneal loss of growth hormone and growth-hormone-binding protein activity in older adults undergoing continuous ambulatory peritoneal dialysis: comparison with haemodialysis patients and normal subjects.

Serum concentrations and peritoneal losses of growth hormone (GH) and of growth-hormone-binding protein (GH-BP) activity in 13 patients undergoing continuous ambulatory peritoneal dialysis (CAPD) were compared with those of 13 patients on haemodialysis and 13 normal subjects. The individuals in the three groups were matched by age (40-83 years), gender, and serum glucose concentration. In addition CAPD and haemodialysis patients were matched by haematocrit, serum creatinine and albumin concentrations, and period of time on dialysis (0.5-127 months). GH in the serum and in the peritoneal effluent were measured by radioimmunoassay (RIA) and NB2 bioassay. GH-BP activity was analysed by binding assay and expressed as a percentage of the specific binding of GH. In the haemodialysis patients, serum GH was significantly greater and serum GH-BP activity significantly less than in the CAPD patients and control subjects. Between the two latter groups no significant differences in GH or in GH-BP activity were observed. GH bioactive/immunoactive ratios in the three groups were similar. Both GH and GH-BP were detected in the peritoneal effluent of CAPD patients, in whom an overnight (8-h) peritoneal loss of GH (8.0 +/- 1.4 x 10(-3) micrograms/h/1.73 m2) was strongly correlated with serum GH (r = 0.840). Circulating GH and GH-BP activity were influenced by serum creatinine and haematocrit. In addition a positive relationship was observed between GH-BP activity and body mass index and between GH and time on dialysis. These data reaffirm that older adults undergoing haemodialysis, unlike CAPD patients, exhibit persistent abnormalities in GH-GH-BP axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

Serum levels and peritoneal loss of prolactin in CAPD patients.

We studied the serum levels and peritoneal transport of prolactin in 13 CAPD patients and compared with 8 patients on hemodialysis and 10 normal subjects matched by age (30-78 years), sex, body mass index and serum glucose concentrations. CAPD and hemodialysis patients were matched also by hematocrit, serum creatinine, albumin concentrations and duration and dialysis (0-79 months), the prolactin levels in serum and in effluent were measured by RIA and NB2 bioassay. CAPD patients had higher serum prolactin levels than did hemodialysis-treated patients and control subjects. The bioactive/immunoactive ratio of serum prolactin in CAPD patients was 0.7 +/- 0.1 versus 0.9 +/- 0.1 in the control subjects (P less than 0.05) and 0.8 +/- 0.04 in the hemodialysis patients, mean +/- SEM. A significant linear correlation was demonstrated between serum levels and 8 hr peritoneal mass transfer of this hormone. A notable drop of prolactin took place after the first hour of dialysis. Serum prolactin was not influenced by peritoneal protein loss, glucose absorption rate or duration of CAPD. From this study we may conclude that hyperprolactinemia associated with CAPD is not affected by continuous peritoneal loss of prolactin, demonstrating only a slight decrease in bioactivity.

Adult↗
PubMed1991

Serum cholesterol and mortality among Japanese-American men. The Honolulu (Hawaii) Heart Program.

Hawaiian men of Japanese ancestry followed up for 18 or more years after a baseline examination showed a quadratic distribution of death rates at different levels of serum cholesterol. Mortality from cancer progressively decreased and mortality from coronary heart disease progressively increased with rising levels of serum cholesterol. There was a positive association between baseline serum cholesterol levels and deaths from coronary heart disease at 0 to 6 years, 7 to 12 years, and 13 years and longer after examination. The inverse relationship between cancer and serum cholesterol levels was stronger in the first 6 years than in the next 6 years and, although still inverse, lost statistical significance after 13 years. Cancers of the colon and lung showed the strongest association with low baseline serum cholesterol levels, while gastric or rectal cancer failed to show this association. Organ specificity and persistence of the inverse association beyond 6 years suggest that the nutritional demands of cancers may not entirely explain the inverse association with some cancers. The quadratic distribution of deaths in this cohort remained after coronary heart disease, stroke, and cancer were removed from the analysis. For the entire period of observation, the lowest mortalities were found in men with serum cholesterol levels between 4.65 and 6.18 mmol/L (between 180 and 239 mg/dL). Manipulation of serum cholesterol levels below this level would not be desirable if this were to result in increased risk of death from cancer or other disease. This study does not rule out this possibility.

Aged↗
PubMed1990

Kinetics of peritoneal protein loss during CAPD: I. Different characteristics for low and high molecular weight proteins.

We studied the peritoneal protein loss in 13 patients during CAPD using 2 liters of 1.5% dextrose dialysis solutions. We compared the kinetic characteristics of the peritoneal mass transfer and clearance of proteins over a wide range of molecular size, to those of small molecular weight solutes. The peritoneal clearance of all studied proteins and solutes correlated strongly and negatively with their molecular mass. No changes were observed in these clearances during 58 months of dialysis. Unlike the peritoneal mass transfer and clearance of small molecular weight solutes (less than 200) which revealed a remarkable progressive drop after the first hour of an eight-hour dialysis cycle, the mass transfer and clearance of proteins of large molecular weight (greater than 68,000) was continuous throughout the eight hours. The clearance of proteins of small molecular weight (less than 15,000) showed similar kinetics to small solutes (less than 200). These results indicate that long dwell times (6 or 8 hr) of peritoneal dialysis are detrimental for the loss of large molecular weight proteins (such as albumin and immunoglobulins) in view of the negligible dialysance of both small solutes (creatinine and potassium) and "intermediate molecules" (represented by the small molecular weight proteins) during the latter hours of long dwell cycles. Thus we suggest that substituting CAPD (3 x 8 hr or 4 x 6 hr) with CCPD (6 x 1 hr) may limit protein loss in these patients.

Adult↗
PubMed1990

Kinetics of peritoneal protein loss during CAPD: II. Lipoprotein leakage and its impact on plasma lipid levels.

We quantified the plasma levels and peritoneal loss of lipids and lipoproteins, and studied the composition of plasma and effluent lipoproteins in 16 patients on CAPD (5 females and 11 males, 18 to 76 years old). Five patients were studied prospectively (at 0, 1, 3 and 6 months) and 11 patients at 6 to 58 months on CAPD (N = 30). Elevated levels of plasma VLDL and reduced levels of plasma HDL were maintained in these patients throughout 58 months of CAPD, whereas the initially increased LDL levels showed a tendency towards normalization. All plasma lipoproteins (VLDL, IDL, LDL and HDL) were present in the peritoneal effluent. The lipoproteins isolated from plasma and peritoneal fluid shared a similar lipid and apolipoprotein composition. The peritoneal transport characteristics of plasma lipoproteins were similar to other plasma macromolecules. Their clearance correlated with their molecular mass, plasma concentration and dwell time, but was not affected by duration of CAPD treatment. The plasma lipid and lipoprotein levels were unaffected by the rate of glucose absorption. The peritoneal protein clearance correlated positively with plasma levels of triglyceride and LDL, and negatively with plasma HDL. An inverse correlation was observed also between plasma levels of HDL and its peritoneal clearance (r = -0.393, P less than 0.025, N = 30). The continuous peritoneal loss of HDL and the hypertriglyceridemia were found to contribute most to the persistent low plasma levels of HDL in CAPD patients, and thus may lead to the accelerated atherosclerosis observed in these patients.

Adult↗
PubMed1989

Predictors of sudden cardiac death among Hawaiian-Japanese men.

A cohort of 7,591 middle-aged Hawaiian-Japanese men free at initial examination of evidence of coronary heart disease or stroke were followed starting in 1965. Between 1965 and 1983, 1,342 of these men died; 229 deaths occurred less than 24 hours after the onset of the terminal episode, of which 98 deaths occurred in less than one hour. In the category of deaths occurring less than one hour after onset, the risk characteristics of those whose deaths were attributed to coronary heart disease and those whose deaths were attributed to an unknown cause were similar. It is appropriate to combine them as "sudden cardiac death." In the category of deaths occurring one to 24 hours after onset, the risk characteristics of those whose deaths were attributed to coronary heart disease and those whose deaths were attributed to an unknown cause differed. It is not appropriate to assume coronary heart disease as the underlying cause of death in this unknown cause group. The predictors of sudden cardiac death were blood pressure, serum cholesterol, serum glucose, cigarette smoking, history of parental heart attack, and electrocardiographic evidence of left ventricular hypertrophy or strain. Inversely related to risk were alcohol intake and the number of years spent in Japan. No factor distinguished those at risk for sudden cardiac death from those at risk for other manifestations of coronary heart disease.

Blood Glucose↗
PubMed1989

Response bias in the Honolulu Heart Program.

The 14-year incidence rates (1969-1982) for coronary heart disease, cerebrovascular disease (stroke), total mortality, and cause-specific mortality were compared between 8,006 examined and 3,130 nonexamined men of the Honolulu Heart Program using identical surveillance procedures. There was a significant decrease in examination participation with increasing age. Examined men smoked less, weighed more, had a higher level of education, and had a lower percentage of never-married status than did nonexamined men. Total mortality rates, cancer mortality rates, and coronary heart disease incidence rates were higher in nonexamined men, while there were no differences in stroke rates. The average annual response error for total mortality and coronary heart disease rates was underestimated at 8.7% and 5.4%, respectively. The differences in rates were greatest during the first half of the follow-up period and converged during the second half. By the end of 10 years, there were no differences between nonexamined and examined men for any of the endpoints studied. The pattern of convergence of rates suggests a diminishing healthy participant advantage over time. In conclusion, a response bias did occur in this study, but the effect was small and did not alter any of the earlier findings concerning the relative incidence of cardiovascular disease. Because the degree of response bias can vary widely depending on when during follow-up a particular analysis is undertaken, it is recommended that prospective studies monitor, insofar as possible, a sample of nonparticipants in order to ensure valid results.

Aged↗
PubMed1989

Serum and effluent lysozyme (muramidase) activity in CAPD patients.

The elevated serum lysozyme activity in 13 chronic renal failure patients (n = 26) dropped significantly during their first three months of CAPD and subsequently returned to initial levels. When compared with peritoneal mass transfer of lysozyme and serum creatinine levels, a distinct correlation was observed between these and the fluctuations in serum lysozyme activity recorded up to three years of CAPD (r = 0.319, P less than 0.05 and r = 0.425, P less than 0.025, respectively). A notable drop in the mass transfer of this low molecular weight protein took place after the first hour of dialysis. We concluded that long-term CAPD does not affect serum lysozyme activity and that passive loss across the peritoneal membrane could account for the lysozyme found in the effluent fluid.

Adolescent↗
PubMed1988

A comparison of the 12-year mortality and predictive factors of coronary heart disease among Japanese men in Japan and Hawaii.

The mortality and predictive factors of coronary heart disease among men of Japanese ancestry in Japan and Hawaii were compared on the basis of 12 years follow-up data using comparable methods of case ascertainment and risk factor measurements. Among 1,687 men (Japan) and 7,536 men (Hawaii) who were free of coronary heart disease and aged 45-69 at baseline examination in 1965-1968, 20 (Japan) and 123 (Hawaii) cases of fatal coronary heart disease were identified. The age-adjusted mortality rate was 40% higher in Hawaii than in Japan. The difference was not statistically significant, but consistent with earlier studies. More than half of this difference in mortality rate was attributed to different levels of known risk factors in the two cohorts. In multivariate analysis using the combined population, age, blood pressure, serum cholesterol, serum glucose, cigarette smoking, and alcohol intake (inversely) remained as significant predictors of coronary heart disease mortality. Although the associations of risk factors with coronary heart disease tended to be stronger in Hawaii than in Japan, there was no statistically significant difference in regression coefficient for any of the risk factors studied. These findings cannot be claimed to be definitive because of the small number of cases, especially in Japan.

Actuarial Analysis↗