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Biomedical subjects

R A Hiatt

Publications and source records attributed to R A Hiatt.

At least 91 records · Page 5Linked to original sources
PubMed1982

Frequency of urolithiasis in a prepaid medical care program.

The rate of occurrence of stones of the urinary tract was assessed in a large population served by the Northern California Kaiser Foundation Health Plan. The study involved three separate groups. First, data were obtained by questionnaire from approximately 175,000 adults who took a multiphasic health checkup in the period 1964-1972; of these generally well adult members, 26.2/1000 persons (32.0/1000 men and 21.0/1000 women) reported having ever been told by a physician that they had a urinary tract stone. Second, data were obtained from 139,000 persons served by the San Francisco outpatient facility in 1970-1972; 1.22/1000 per year (1.81/1000 men and 0.59/1000 women) had an initial diagnosis of a "new or recurrent" stone of the upper urinary tract. The third set of data was procured from the entire Northern California region in 1971-1975; 0.36/1000 (0.52/1000 men and 0.19/1000 women) were discharged from a hospital each year with a diagnosis of upper urinary tract stone. All rates were age-adjusted to the 1960 US Census population. Of these three rates, the rate derived from the outpatient visit record most closely estimates incidence, since nearly all persons who are hospitalized are first seen as outpatients. Rates of kidney stone diagnosis were three times more common in men and, although rare before 20 years of age, the frequency increased rapidly and peaked in the age group 40 to 59 years. Rates were approximately twice as high in whites as in blacks and Orientals; the frequency of stones was inversely related to socioeconomic status as measured by level of education. Over 90% of stones occurred in the upper urinary tract, and the majority contained calcium oxalate. Population-based rates of occurrence of kidney stones are not generally available in the United States. Comparisons with the few available studies indicate that rates in the Kaiser Foundation Health Plan population may be high.

Adolescent↗
PubMed1982

Characteristics of patients referred for treatment of end-stage renal disease in a defined population.

We studied the incidence of referral for treatment of end-stage renal disease (ESRD) in the Kaiser Foundation Health Plan (KFHP) in northern California from 1972 through 1977. In this population of over 1 million persons, we found an age-adjusted annual incidence of 44.9 per million after 1973, when the Federal ESRD Program went into effect. Age-specific incidence was highest in in men greater than 70 years of age and in women in the 50- to 59-year age group; the male/female ratio was 1.4:1. The most common diagnoses of patients referred with ESRD were glomerulonephritis (11.4 per million per year), diabetic nephropathy (5.0 per million per year), primary hypertensive disease (3.1 per million per year), and polycystic kidney disease (2.4 per million per year). Estimated rates of referral for ESRD were highest for Blacks, lowest for Whites, and intermediate for Asians. Incidence varied by geographic area within the health plan service area and was highest where the percentage of the Black population was highest.

Adolescent↗
PubMed1982

Breast cancer and serum cholesterol.

Recent studies have suggested a role for dietary fat in the etiology of breast cancer. The relation of serum cholesterol and other serum lipid measures to breast cancer incidence was investigated in a cohort of 95, 179 women who had multiphasic health checkups from 1964 through 1972. Through 1977, 1,035 new breast cancer cases occurred in over 752,000 person-years of follow-up. Age-adjusted incidence rates were 1.45, 1.37, 1.31, and 1.40/1,000 person-years from the lowest to the highest quartile of serum cholesterol level, respectively. Similarly, no statistically significant relation was detected between beta-lipoprotein or total lipids and breast cancer. The sample size was sufficiently large to have detected a relative risk of 1.4 or larger with a probability of 99.9% at the 0.05 level of significance. The expected relation od breast cancer to established risk factors was confirmed by univariate analysis, and serum cholesterol and breast cancer were not associated after simultaneous consideration of nine other risk factors by multivariate analysis. These data suggest that the postulated causal relation between dietary fat and breast cancer does not act via an effect on circulating lipid levels.

Adolescent↗
PubMed1980

Serial observations of circulating immune complexes in patients with acute schistosomiasis.

To define further the role of circulating immune complexes in acute schistosomiasis, serial determinations of [125I]Clq binding activity (ClqBA) in 15 patients with this disease were made before and after treatment with niridazole. Levels of ClqBA were elevated in 13 of these patients and in general rose early in the course of disease, reaching maximal levels by 10 weeks after exposure; the levels were correlated with disease severity (r = 0.70, P less than 0.01) and with the concentration of Schistosoma mansoni eggs in the stool (r = 0.59, P less than 0.05). The rise and fall in levels of ClqBA was associated in most instances with the temporal course of other laboratory values reflecting disease activity. The close association of circulating immune complexes with measures of disease activity suggests that these complexes are important in the pathogenesis of acute schistosomiasis.

Acute Disease↗
PubMed1980

The Boqueron Project after 5 years: a prospective community-based study of infection with Schistosoma mansoni in Puerto Rico.

The Boqueron Schistosomiasis Project is a prospective community-based study of Schistosoma mansoni infection after the interruption of transmission by nonchemotherapeutic control measures. The study methods and the parasitologic results of the first five annual stool surveys are described in this report. In the first year, 1972, among 904 inhabitants (88% of the total population) the prevalence of infection was 40%, and the geometric mean intensity of infection among positives was 16.1 eggs per gram (epg). Snail control was begun in early 1973 with molluscicides and habitat modification. Intensive monitoring every 2 weeks revealed only 63 noninfected Biomphalaria glabrata in the community during the subsequent 4 years. The incidence of new infectins among people negative in all previous surveys dropped from 17% in 1972 to 1% in 1974 and has remained negligible since then. Among young children and newborn, only four new infections (all less than 5 epg) were found after the first control year. Despite this low rate of transmission, prevalence only decreased from 37% to 34%, and the population geometric mean fecal egg output has not substantially changed in a cohort of 528 individuals examined in each of the six annual surveys. Possible reasons for the minimal change in parasitologic status are discussed and include water contact behavior outside the community and changes in laboratory techniques. Data from the first 5 years of the study suggest that in a population where mean intensity of infection with S. mansoni is low, further decreases in prevalence and intensity of infection occur slowly. The implications for control programs based on nonchemotherapeutic measures are discussed.

Adolescent↗
PubMed1979

Factors in the pathogenesis of acute schistosomiasis mansoni.

Acute schistosomiasis mansoni was studied in 26 Puerto Rican patients whose clinical presentations differed widely in severity. Severity of illness was found to be positively correlated (r = 0.79) with the intensity of infection as measured by the concentration of eggs of Schistosoma mansoni in stool specimens. However, some patients had severe illness but relatively light infections. The disappearnace of symptoms and return toward normal of laboratory measures of disease activity were not associated with any diminution in the fecal egg count. Elevations of IgG, IgM, IgE, and of titers of anibody in serum indicated that the illness is associated with intense immune activity. The magnitude of the IgG and IgE responses was related to intensity of infection. The fact that incubation periods were shorter than the time needed for schistosomes to reach adulthood and lay eggs suggests that the syndrome can be initiated by parasite stages present before oviposition. No marked changes in complement (C3, C3p, C4, and CH50) and no signs of renal disease were noted in any of these patients.

Acute Disease↗
PubMed1979

Circulating immune complexes in acute schistosomiasis.

The sera of patients with acute and chronic schistosomasis were tested for the presence of circulating immune complexes with the 125I-Clq binding assay. Fourteen out of fifteen (93%) patients with acute schistosomiasis had elevated 125I-Clq binding activity, while only two out of eleven (18%) patients with chronic disease had C1q binding complexes. This difference was significant (P less than 0.001) and paralleled the degree of clinical didsease activity between the two groups of patients. IgG and IgM were readily detected in all of these circulating complexes but the specific parasite antigens initiating their formation could not be defined. The level of circulating immune complexes was inversely correlated with the absolute eosinophil counts for individuals in the acutely infected group, an observation compatible wiht the hypothesis that a functional role for the eosinophil is the destruction and elimination of immune complexes.

Acute Disease↗
PubMed1978

Limitations of the intradermal test for schistosomiasis mansoni: experience from epidemiologic studies in a Puerto Rican community.

The intradermal reaction with Schistosoma mansoni adult-worm antigen (35-40 microgram/ml nitrogen) was evaluated as an edpidemiologic tool in an endemic Puerto Rican community where the prevalence of S. mansoni infection was 36% and the geometric-mean egg count was 17.6 eggs/g. Subcutaneous injections of antigen were made in forearms, and stool specimens were examined for S. mansoni eggs by a formol-ether concentration method. Of 296 persons tested, 43% had positive intradermal reactions (greater than or equal to 1.0 cm 2 at least twice the area of the control wheal), compared to 48% positive stool examinations. However, sensitivity was low at 36% for children 14 yr old or less, and only 73% to 79% for adults. The test results were very specific for children (96%), but 32% of stool negative adults were positive. Mean wheal area was not directly related to intensity of infection as determined by egg counts in either children or adults, but did increase directly with age. Mean wheal areas were greater for males than females (both children and adults) at all intensities of infection. Because of unsatisfactory sensitivity and specificity the intradermal test may overestimate the prevalence of infection when rates are low, and underestimate prevalence of infection when rates are high. For its proper interpretation, complementary parasitologic data from stool surveys are required.

Adolescent↗
PubMed1978

The acquisition and loss of antigen-specific cellular immune responsiveness in acute and chronic schistosomiasis in man.

To characterize the development and evolution of cellular immune responsiveness in individuals infected with the parasite Schistosoma mansoni, we studied fifteen patients with acute, subacute and chronic schistosomiasis. Lymphocytes from the three acutely infected patients responded vigorously to schistosome antigens in an in vitro blastogenic assay. By contrast, cells from nine chronically infected individuals were essentially unreactive to these same antigens. Patients infected for an intermediate period of time (9 months) generated responses between those of acute and chronic patients. The diminished responsiveness of chronically infected individuals was specific for schistosome antigens and did not extend to humoral immune responses. Following treatment of the infection with niridazole, these patients temporarily regained responsiveness to schistosome antigens. From these data we speculate that during the course of this parasitic helminth infection there develops a progressive and specific modulation of antigen recognition and proliferation by lymphocytes to schistosome antigens, and that such diminished immune reactivity may be important in maintaining the unique biological relationship which exists between a host and its parasites.

Acute Disease↗
PubMed1977

Morbidity from Schistosoma mansoni in a Puerto Rican community: a population-based study.

A population-based approach was used to investigate morbidity from Schistosoma mansoni in a rural community in eastern Puerto Rico that was representative of remaining endemic foci on the island. In 1974 the prevalence of infection 855 of 1,056 inhabitants was 32.7% and the geometric mean egg output was 17.6 eggs per gram. A standardized medical history was obtained, and physical and laboratory examinations were performed on 737 (70%) of the community residents. Quantitative S. mansoni egg counts were performed on 1 gram of feces with a modified Ritchie formol-ether concentration technique; other intestinal parasites were recorded on a semi-quantitative basis. Interviews and physical examinations were conducted "blind" to minimize observer bias, and statistical analysis was done on data from 149 infected subjects and 149 noninfected controls matched by age and sex. For subjects under 20 years of age the frequency of hookworm infection and trichuriasis and absolute eosinophilia was significantly higher in the infected group, but no difference was found in the frequency of signs and symptoms of schistosomiasis. For the subjects 20 years and over, the symptom "blood in the stool" was reported more frequently in the infected group, but hematocrit level did not differ between infected and noninfected controls. Although palpable livers were noted more frequently in infected (8) than in noninfected (1) subjects 20 years and over, further evaluation of these subjects cast doubt upon a causal role for S. mansoni. These data indicate that morbidity from S. mansoni infection in the community is low, a finding consistent with the apparent decline in S. mansoni morbidity in Puerto Rico during recent decades and the relatively low intensity of infection in this community. Nevertheless, because of the sporadic occurrence of S. mansoni-induced disease on the island, and because heavily infected subjects are clearly at greater risk of disease, we are recommending treatment for community residents with high egg output.

Adolescent↗
PubMed1977

'Long-distance' lymphocyte study. The effects of transporting blood in lymphocyte blastogenic responses.

A comparison of blastogenic responsiveness to antigens and mitogen by human lymphocytes was made between cells which had been processed for culture immediately following blood collection and cells obtained from blood collected 9-11 hr previously and transported via commercial airline from the patients' homes to our laboratory. There were no significant differences in the responses of transported and non-transported cells if the blood was maintained at ambient temperature during the period of shipment. Chilling the blood during transport, however, resulted both in decreased stimulation of the cells and increased 'background' activity in unstimulated cultures. These findings indicate the feasibility of carrying out both limited immunological evaluations and extended periods of follow-up for patients located at considerable distances from a research laboratory.

Adult↗
PubMed1976

Morbidity from Schistosoma mansoni infections: an epidemiologic study based on quantitative analysis of egg excretion in two highland Ethiopian villages.

Although human infection with Schistosoma mansoni is known to be widespread in Highland Ethiopia, no information is available on its public health impact. A sample of the inhabitants of two typical villages in the endemic region north of Lake Tana were studied by clinical and quantitative parasitologic methods. One village had a moderately high prevalence (43.3%), while the second, chosen for comparison, had a very low prevalence (10.7%). No evidence of severe hepatosplenic disease was found in 343 persons examined. Symptons and mild hepatomegaly compatible with S. mansoni infection were common, and in the high prevalence village complaints of abdominal pain and blood in the stool were significantly related to S. mansoni egg counts. However, all signs and symptoms compatible with S. mansoni infection, including hepatomegaly, were of greater or similar frequency in the village with the low prevalence of infection. The findings of minimal morbidity are compatible with the level of intensity of infection found in the area and are consistent with the findings from morbidity studies based on quantitative egg counts in other areas of the world.

Adolescent↗
PubMed1976

A modification of the formol-ether concentration technique for increased sensitivity in detecting Schistosoma mansoni eggs.

The low Schistosoma mansoni egg counts generally found in Puerto Rico require a sensitive technique for epidemiologic studies. The Ritchie formol-ether concentration technique has been modified to make it more useful for this purpose. The modified technique was compared with the older technique by analyzing fecal specimens from ten individuals with varying levels of infection. It was also compared with the Kato thick-smear technique with specimens from 25 other patients. In both series, three replicates of each technique were done on each stool. Results indicated that the modified technique was more sensitive than the older technique in terms of number of eggs counted, and that the sediment was smaller and clearer and required about 15% less time to examine. In comparison with the Kato technique, it was more successful in detecting light infections, although at higher levels of intensity, when expressed on an eggs-per-gram basis, the thick smear detected relatively more eggs. For the series as a whole, coefficients of variation for the three replicates done on each stool were smaller for the modified concentration technique than for the Kato technique. This is interpreted to reflect satisfactory reproducibility of the concentration technique when compared to the Kato technique. The concentration technique has the additional advantages over the thick smear of detecting other intestinal parasites and allowing for transportation and storage after feces are preserved in formalin.

Ether↗