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D J Thompson

Publications and source records attributed to D J Thompson.

At least 73 records · Page 4Linked to original sources
PubMed1982

Proposal for a collaborative epidemiology study of prostate cancer in the Pacific Basin.

Incidence rates of invasive prostate cancer vary markedly among countries of the Pacific Basin, and migrant studies have shown that this is at least partly due to environmental factors. Future epidemiology studies in these countries should be conducted so that this variability in incidence can be explained. Prevalence ratios of latent prostate carcinomas of the infiltrative type vary with incidence rates of invasive carcinomas, and a collaborative case-control study of infiltrative and noninfiltrative latent carcinomas in the Pacific Basin, combined with a standardized pathological review of specimens obtained at autopsy, could provide new etiological clues. Factors that should be investigated include fertility and sexual practices; exposure to zinc, cadmium, and mercury compounds; prior benign prostatic hypertrophy; diet; conditions that may alter endogenous levels of androgens and estrogens; and family history of diseases of the prostate. Events during the fourth decade of life may be of particular importance. Case-control studies of invasive prostate cancer in high- and low-risk populations are currently being conducted, and additional ones are not warranted until results from these are available. Investigators should use these results in planning the proposed study of latent prostate carcinoma.

Alaska↗
PubMed1982

Epidemiology of testicular cancer in the Pacific Basin.

Although a rare tumor, testicular cancer shows substantial international variation in incidence. In whites, the peak incidence occurs at 25-30 years of age, with a second increase in old age. Blacks have much lower rates than do whites. The rate of increase in the incidence and mortality of this cancer has been consistent but low during the past 40 years. Risk factors identified in epidemiology studies of testicular cancer include cryptorchidism (best documented), inguinal hernia, testicular injury, wearing of tight-fitting underclothing, obesity, maternal use of exogenous estrogens during pregnancy, higher social class, and professional occupations. Epidemiological evidence provides two etiologic hypotheses: a relative hormone imbalance, particularly an excess of estrogen, and a failure of normal thermal regulation of the testis. In the Pacific Basin region, notable variation in incidence rates is also seen. High-risk populations include whites, Polynesians (in Hawaii and New Zealand), and Native Alaskans. Low-risk groups include Filipinos (in Hawaii and Manila), Japanese (in Hawaii and Japan), Indians, and Malays. Most of this variation occurs in the younger ages (0-54 yr). Several areas for potentially fruitful research on this cancer in the Pacific region are given.

Adolescent↗
PubMed1981

Multi-channel laboratory testing and the unexpected abnormal result: a statistical myth corrected.

Multi-channel automatic analysers generate unexpected abnormal test results impacting medical economics, policy and practice. Critics caution that many such abnormal results should be expected due simply to the statistical definition of normal limits. With a test battery of n channels the probability p that a healthy individual will be within limits on all tests, each with probability s, is usually predicted p = sn. In most clinical situations, however, the assumptions upon which this formula rests are not met and it overestimates the occurrence of abnormal results. In three screening programmes involving blood chemistry batteries on 769 patients the formula gave overestimates (p less than 0.001) of the percentage of individuals with at least one abnormal result. For a battery of eight tests 33.7 percent of patients were predicted to have abnormal results but only 20.6 percent were observed, with 14 tests 51.2 percent were predicted and only 37.1 percent observed, for 17 tests 58 percent were predicted and only 33.3 percent observed. Clinical judgment, not misapplied probability theory, should guide the physician's strategy in evaluating abnormal test results.

Adult↗
PubMed1981

The digestion by cattle of grass silage made with formic acid and formic acid-formaldehyde.

1. A primary growth crop of perennial ryegrass (Lolium perenne L., cv. S23) was partially wilted and ensiled after the application of either formic acid-water (1:3, w/v; 7.11 l/t fresh herbage; control diet C) or formic acid-formaldehyde (1:1, w/w; 8.8 l/t fresh herbage; formaldehyde treated diet F) which supplied 50 g HCHO/kg crude protein (nitrogen (N) x 6.25). The two silages were fed separately and a third diet comprising formaldehyde-treated silage, supplemented with urea (20 g/kg dry matter DM) at the time of feeding was also examined (diet FU). 2. The three diets were fed at a level of 16 g DM/kg live weight to six 3- to six-month-old cattle fitted with rumen and re-entrant duodenal cannulas in two 3 x 3 Latin Square experiments, and measurements were made of the digestion of energy, carbohydrate and N. 3. The formaldehyde-treated silage had a lower content of fermentation acids and ammonia-N, and a higher content of water-soluble carbohydrate and total amino acids. The apparent digestibility of organic matter, energy and N were depressed (P less than 0.05, P less than 0.05 and P less than 0.01 respectively) by treatment with formaldehyde, but cellulose and neutral-detergent fibre digestibility were unaffected. 4. Within the rumen the digestion of organic matter, cellulose and neutral-detergent fibre were unaffected by formaldehyde treatment or supplementation with urea. Microbial protein synthesis in the rumen was similar for the three diets (average 131 g/kg apparently digested organic matter in the rumen). 5. The application of formic acid-formaldehyde increased (P less than 0.05) the amount of food protein escaping degradation in the rumen (4.76 diet C, 6.89 diet F; 7.07 diet FU g/kg protein intake). The contribution of amino acids of dietary origin at the duodenum increased (P less than 0.05) from 50 (diet C) to 80 (diet F) and 82 (diet FU) g/kg DM intake, and the flow of total amino acids at the duodenum was 33% higher (P less than 0.001) in cattle fed formic acid-formaldehyde silage diets compared with the control silage due to the reduction in degradation of protein at ensiling and in the rumen.

Amino Acids↗
PubMed1981

Acetaldehyde-dependent changes in hemoglobin and oxygen affinity of human erythrocytes.

In the presence of acetaldehyde, metabolizing human erythrocytes accumulate an altered hemoglobin product showing chromatographic similarity to hemoglobin AIa or AIb. The adduct is stable to overnight dialysis with an intracellular half-life of about 5.5 days. Adduct formation is accompanied by proportional changes in cell oxygen affinity (decrease in P50 of 3 mm Hg/mM adduct). Little unaltered hemoglobin remains after overnight incubation in 15 mM acetaldehyde, with significant adduct formation and marked reduction of cell ATP occurring after prolonged incubation in as little as 0.5 mM acetaldehyde.

2,3-Diphosphoglycerate↗
PubMed1980

Acoustic reflex growth in the aging adult.

Growth in amplitude of the acoustic reflex to filtered noise and tones of 500, 1000, and 2000 Hz was measured with an aural acoustic-admittance meter in 30 persons between the ages of 20 and 79 years. Although thresholds of the acoustic reflex did not vary significantly across the age range of the subject sample, the rate of growth in amplitude decreased linearly with increase in age decade. Given information on the aging of structures in the acoustic reflex pathway, the growth data are interpreted tentatively to mean that the contractual capacity of the stapedius muscle is diminished in older ears.

Adult↗
PubMed1980

Eight-year toxicity study in monkeys and reproduction studies in rats and rabbits treated with probucol.

Probucol [4,4'-(isopropylidenedithio)bis(2,6-di-tert-butylphenol)], a hypocholesterolemic agent, was given orally to male and female rhesus monkeys at 0, 60, 125, 250, and 500 mg/kg . d for more than 8 yr without adverse effect. Of 40 monkeys on test, 14 were killed for interim studies (wk 81 and 102), 21 were maintained for more than 8 yr, and 5 were submitted for necropsy for conditions unrelated to treatment. Monitored parameters included growth rate, demeanor, hematology, clinical chemistries, urinalyses, ophthalmoscopy, organ weights, and gross, histopathologic, and electron microscopic evaluations. Bone marrow smears at the conclusion of the test revealed no differences between control and treated animals. Electron microscopy of liver specimens from monkeys treated for 8 yr revealed comparable hepatocellular ultrastructure in control and treated monkeys. Probucol was given orally at 0, 100, 500, and 1000 mg/kg to Sprague-Dawley rats during appropriate time intervals to evaluate effects on fertility and postnatal development. The same dose levels were given during organogenesis, or in some cases prior to breeding and throughout organogenesis, to Sprague-Dawley rats and New Zealand white rabbits. No adverse effects on fertility or postnatal development were observed in rats, and no evidence of teratogenicity was observed in either species. The results indicate that probucol does not affect reproduction of rats, lacks teratogenic potential in the species studied, and is nontoxic to subhuman primates treated for more than 8 yr.

Abnormalities, Drug-Induced↗
PubMed1980

Prevalence of prior hysterectomy in the Seattle-Tacoma area.

Hysterectomy is the most common major surgical procedure performed in the United States. The frequency of hysterectomy among women in the general population is of interest because it affects the population at risk for uterine diseases and because the procedure itself carries significant personal and socioeconomic consequences. We studied factors related to the occurrence of hysterectomy by interviewing a representative sample of women ages 35-74 (n= 1087) in two urban Washington counties during 1976-1977.One-third of the women studied had had a hysterectomy. Later birth cohorts were at higher risk. The ageadjusted prevalence of prior hysterectomy was negatively associated with education and age at first childbirth; it was positively associated with parity, history of irregular menses, and history of a variety of other health conditions. Contrary to expectation, income was negatively associated with hysterectomy rates in one county and showed no association in the other. Part of the income effect was due to confounding by age at first childbirth, which was a surprisingly strong predictive factor. WE CONCLUDE THAT: 1) despite economic predictions based on the discretionary nature of the procedure, hysterectomies are not necessarily more common among high-income women; 2) age at first childbirth may be a more important risk factor for uterine disease than previously thought; and 3) estimates of hysterectomy frequency based on clinic populations may be misleading. (Am J Public Health 70:40-47, 1980.)

Adult↗
PubMed1980

Industrial considerations related to fluoride toxicity.

It is generally recognized that the inorganic phosphate ingredients in mixed feed or mineral supplements are the principal source of fluoride in the feed. Today, there are several types of feed phosphates available to the feed industry. This paper discusses how these supplemental phosphates are produced, the quantities utilized by the feed industry and what species consume them, and describes their phosphorus content, fluoride content and general cost. The phosphate industry, along with university researchers and the Association of American Feed Control Officials, set up standards for safe levels of fluoride in feed phosphates. A P toF ratio of 100:1 was adopted in 1952 for any product sold to the feed industry as "defluorinated phosphate." The phosphate industry has felt that products with this ratio are safe, and, on the basis of evidence available today, it is still felt that this is a safe level of fluoride in supplemental feed phosphates. Industry has the technology to produce feed phosphates of lower fluoride content; however, there is an increased cost in further reducing fluoride content.

Animal Feed↗
PubMed1980

Multi-test screening and the chances of being normal.

Screening programs involve responsibility for appropriate action on abnormal test results. When multiple-test screening batteries are used, a simple probability formula is commonly used to predict the proportion of healthy individuals who will have one or more abnormal test results occur by chance alone. This formula is valid only when the assumptions upon which it rests are met in the population being tested. In many situations the assumptions are not met and the formula overestimates the occurrence of abnormal results in healthy populations. Data for three screening programs involving blood chemistry test batteries on 769 patients document this overestimate and its magnitude. Clinical judgment, not misapplied probability theory, should guide the physician's strategy in evaluating abnormal results of screening tests.

Blood Chemical Analysis↗
PubMed1979

Interaction of divalent cations with beta-galactosidase (Escherichia coli).

Although the addition of various divalent metals to beta-galactosidase resulted in apparent activation, only Mg2+ and Mn2+ actually did activate. The apparent activation by the other divalent metals was shown to be due to Mg2+ impurities. Calcium did not activate, but experiments suggested that it did bind. Other divalent metals which were studied failed to bind. The dissociation constants for Mg2+ and Mn2+ were 2.8 X 10(-7) and 1.1 X 10(-8) M, respectively, and in each case one ion bound per monomer. These constants corresponded very closely to apparent values which were obtained from activation studies. The apparent binding constant for Ca2+, obtained from competition studies, was 1.5 X 10(-5) M. Data were obtained which showed that Mg2+, Mn2+, and Ca2+ all compete for binding at a single site. Of interest and of possible molecular biological importance was the observation that, while Mg2+ bound noncooperatively (n = 1.0), Mn2+ did so in a highly cooperative manner (n = 3.4). The binding of Mn2+ (as compared to Mg2+) resulted in a twofold drop in the Vmax for the hydrolysis and transgalactosylis reactions of lactose but had little effect on the Vmax of hydrolysis of allolactose, p-nitrophenyl beta-D-galactopyranoside (PNPG), or o-nitrophenyl beta-D-galactopyranoside (ONPG); Km values were not effected differently for any of the substrates by Mn2+ as compared to Mg2+. When very low levels of divalent metal ions were present (0.01 M EDTA added) or when Ca2+ was bound with lactose as the substrate, a greater decrease was observed in the rate of the transgalactosylic reaction than in the rate of the hydrolytic reaction, and the Km values for lactose and ONPG were increased. Of the three divalent metal ions which bound to beta-galactosidase, only Mn2+ had significant stabilizing effects toward denaturing urea and heat conditions.

Calcium↗
PubMed1979

Nontreatment of fever in extended-care facilities.

In a study of decisions not to treat febrile patients, we reviewed the medical records of 1256 people admitted to nine extended-care facilities in Seattle during 1973. Fever, defined as two temperatures of 38.33 degrees C to 38.83 degrees C (101 to 101.9 degrees F), within 24 hours or one temperature greater than or equal to 38.88 degrees C (102 degrees F), developed in 190 patients before two years of stay. Active treatment, defined as antibiotics or hospitalization (or both), was ordered for fever in 109 patients, of whom 10 (9 per cent) died. Active treatment was not ordered for 81 patients, of whom 48 (59 per cent) died. The pre-decision factors that showed a significant relation (P less than 0.05) to such nontreatment were: diagnosis, mental status, mobility, pain, narcotics prescribed, size of the facility, relation of the physician to the patient and medical-record statements documenting the patient's deterioration or plans for nontreatment in general. This pattern of nontreatment suggests that physicians and nurses did not intend to treat these patients actively and that high mortality was expected.

Aged↗
PubMed1979

Acoustic admittance and the aging ear.

Tympanograms were acquired from 60 subjects, 20 through 79 years of age, with normal hearing and no history of otic pathology. Acoustic conductance and acoustic susceptance at the tympanic membrane (GTM and BTM) were derived and acoustic admittance (YTM) was calculated. Statistical analysis of GTM, BTM and YTM showed no significant variation in values across age decades. Comparison of these data with previous reports suggests that the effect(s) of age on measures of static acoustic admittance, and presumably acoustic impedance, is complex.

Acoustic Impedance Tests↗
PubMed1979

Peripheral neuropathy in arsenic smelter workers.

We conducted a double-blind controlled study of individuals exposed to arsenic trioxide in a copper-smelting factory. Subjects fell into three categories of peripheral neuropathy: none, subclinical, and clinical. The subclinical group had no symptoms or signs of numbness or reduced reflexes, but did have reduced nerve conduction velocity and amplitude measurements. Clinical neuropathy groups had signs and symptoms of neuropathy and electrophysiologic abnormalities. The clinical and subclinical groups correlated with increased content of arsenic in urine, hair and nails. The incidence of subclinical and clinical neuropathy was greater in arsenic workers than in unexposed controls.

Adult↗