A short parameter-fitting routine for compartmental models

We have developed a program of 298 FORTRAN statements which obtains the inter-pool exchange rates and other parameters of a compartmental system, working directly from the time course of tracer activity after a bolus injection. The fitting problem - data and model - is specified by the user in a natural syntactic style. The program calculates least-squares estimates, confidence limits and intercorrelation estimates for the fitted parameters. Its small size and conceptual simplicity make the program a powerful practical tool for analyzing tracer studies.

A numerical method for fitting compartmental models directly to tracer data

A numerical method is presented for obtaining the exchange rates of a metabolic compartmental system, working directly from the time course of tracer activity and excretion after bolus injection. The conventional mathematical formulation of this problem, in terms of sums of exponential functions, is bypassed, enabling implementation of the method in a short computer program. An important by-product of the method is a set of variance-covariance estimates for the fitted parameters. The method is tested on "classic" data, both simulated and real. Its capabilities and limitations are demonstrated, and the strategy of its effective application is discussed.

Meningococcal meningitis in northern Ghana: epidemiology and control measures

Hospitalized meningococcal meningitis patients in northeastern Ghana during 1972-1973 were studied to provide baseline information about case clustering and age-specific attack rates to guide meningitis control programs. In 1973, group A meningococci were prevalent and 7% of isolates were sulfadiazine-resistant. In contrast to the age distribution of meningococcal meningitis in North and South America, peak attack rates occurred in 10- to 14-year-old Ghanaians. A mass immunization campaign using group A polysaccharide vaccine in heavily populated areas of the Bawku and Nalgerigu districts is recommended.

Effects of volume expansion and parathyroid hormone on total renal blood flow and its intracortical distribution

Clearance and renal blood flow studies were performed during hydropenia, 2.5 and 10 percent steady-state saline expansion, and acute administration of parathyroid hormone (PTH) in chronically thyroparathyroidectomized (TPTX) dogs and during hydropenia and 10 percent expansion in intact dogs. Renal cortical blood flow distribution was measured with radioactive microspheres In TPTX dogs, 2.5 percent expansion increased sodium excretion but did not alter total or intracortical blood flow. With 10 percent expansion, sodium excretion and juxtamedullary (zone 4) blood flow increased in both TPTX and intact dogs. There was no correlation between the changes in sodium excretion and zone 4 fractional blood flow in either group. Although the acute administration of PTH to TPTX dogs did not alter total or intracortical blood flow, control period hemodynamic data revealed an inner shift of flow in TPTX as compated to intact dogs.These results indicate that (1) massive (10 percent), but not mild (2.5 percent), volume expansion produces an inner shift of cortical blood flow; (2) this shift does not correlate with sodium excretion, nor is it influenced by thyroparathyroidectomy: and (3) PTH does not acutely alter renal blood flow distribution, but its chronic absence is associated with a shift of flow to the inner cortex.

A measles outbreak among adolescents

In a May, 1975, outbreak, 147 adolescents, ages 12 to 19 years, were identified as having measles by a physician or school nurse. One junior high school, with an enrollment of 1,122, contributed 131 of the cases. Of the 147 students, 54 were seen by physicians who also supplied their immunization records; 19 of 54 (35%) had received live measles virus vaccine without measles immune globulin, after age one year. The remaining 35 received: killed virus vaccine only (1), K + L (4), L + MIG (4), L at less than 1 year of age (4), L + ? MIG (4), immune serum globulin only, for exposure (6), no vaccine but history of measles previously (9); history uncertain (3). Hemagglutination-inhibition antibody titers were consistent with the diagnosis of acute measles in 11 children. No index case was identified and no secondary cases occured within the families of the 54 cases. This measles outbreak among seemingly immunized adolescents raises a serious question as to the duration of such protection.

Pharyngeal isolations of adenovirus 31 from a family population

During a 14-month period in 1965 and 1966, adenovirus type 31 was isolated from 26 pharyngeal swabs obtained on a routine schedule from children and adults during a study of respiratory viruses among members of a family population. Eighteen isolations were made in a four-day period, seven within the preceding five months, and the last, eight months earlier. A significant association between the isolation of adenovirus 31 and respiratory or gastrointestinal illnesses was not demonstrable. Limited tests demonstrated neutralizing antibody increases in a few paired sera of infected adults. The virus is antigenically related to adenoviruses 12 and 18 and is capable of inducing soft tissue tumors in mice.

Endocrinology and metabolism in uremia and dialysis: a clinical review

The salient information regarding the effects of uremia and dialysis on each of the metabolic fuels and hormones presented in the preceding sections is summarized in three tables. Tables 1 and 2 provide data on plasma levels, metabolism, dialysance, and literature references for each substance. Table 3 organizes the data according to the general mechanisms by which uremia and chronic dialysis may affect biological substances. Together these tables provide a reasonably complete summary of the information presently available. The pathophysiology of the uremic syndrome is still incompletely understood. The numerous metabolic and endocrine alterations associated with uremia and chronic dialytic therapy underscore the complexity of the problem and identify several specific areas for future research. One which deserves emphasis is the poolic and endocrine abnormalities found in uremia. A recent review by Chantler and Holliday (63) stressed in the importance of protein-calorie deficiency in the pathogensis of growth retardation and disturbed hormonal metabolism in children with chronic renal failure. The importance of this factor in adult patients with chronic uremia has been less well appreciated. However, striking similarities exist between the metabolic and endocrine abnormalities found in protein-calorie malnutrition and those found in uremia. These include, for example, altered albumin and amino acid metabolism, decreased levels of serum transferrin, peripheral insulin resistance and carbohydrate intolerance, elevated levels of glucagon, cortisol and growth hormone, and possibly diminished secretion of thyrotropin and thyroxine. Although not absolutely identical, the similarities between these two clinical syndromes suggest intriguing possible approaches to a better understanding of the pathophysiology of the uremic syndrome and its treatment.

Hemophilus influenzae, type b, antibody frequencies determined with bactericidal and radioimmunoassay tests

Bactericidal and radioimmunoassay (RIA) antibodies to Hemophilus influenzae, type b, were measured in the sera of 85 children aged 18 through 71 months. Bactericidal antibodies were present in only 21% of those over 60 months; RIA levels rose linearly with increasing age (P less than 0.005). Bactericidal antibodies were present in nine of 29 sera with RIA levels greater than or equal to 0.7 mug/ml and in only four of 56 sera with RIA levels less than 0.7 mug/ml (P less than 0.01). The discrepancies between the two tests probably reflect their measurement of different antibodies. Results of the RIA fit the clinical observation that H. influenzae meningitis becomes less frequent with age.

Effects of intravenous hyperalimentation of plasma-lipoproteins in severe familial hypercholesterolaemia

The plasma-lipoprotein response to intravenous hyperalimentation was studied in three patients with severe familial hypercholesterolaemia. Hyperalimentation substantially lowered plasma concentrations of cholesterol, low-density lipoproteins (L.D.L.P.), and high-density lipoproteins. The chemical composition of L.D.L.P. did not change. Triglyceride levels increased slightly in two patients and decreased in the third. Turnover of radiolabelled L.D.L.P. was disturbed as L.D.L.P. concentration fell but then returned to normal. The mechanism by which intravenous hyperalimentation rapidly lowers plasma-cholesterol in severe hypercholesterolaemia is unknown.

Amphotericin B therapy in an anephric patient

Serum levels of amphotericin B were serially determined during and after a course of therapy in an anephric patient who developed systemic candidiasis after an unsuccessful renal transplantation. There was no progressive accumulation of drug in serum, and the pattern of disappearance of drug from serum was similar to that published for patients with normal renal function. The dialyzability of amphotericin B was studied in vivo during a 6-h period of hemodialysis, by an in vitro dialysis of amphotericin B in water by using similar equipment, and a Pellicon membrane filter which retains molecular species of 100,000 molecular weight and higher. These studies revealed that the drug is not dialyzable with conventional hemodialysis membranes, regardless of protein binding in plasma, and is excluded from passing through the Pellicon membrane filter.