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PubMed2002

Lead, zinc and copper accumulation and tolerance in populations of Paspalum distichum and Cynodon dactylon.

Both Fankou and Lechang lead/zinc (Pb/Zn) mine tailings located at Guangdong Province contained high levels of total and DTPA-extractable Pb, Zn and Cu. Paspalum distichum and Cynodon dactylon were dominant species colonized naturally on the tailings. Lead, zinc and copper accumulation and tolerance of different populations of the two grasses growing on the tailings were investigated. Tillers of these populations including those from an uncontaminated area were subjected to the following concentrations: 5, 10, 20, 30 and 40 mg l(-1) Pb, 2.5, 5, 10, 20 and 30 mg (l-1) Zn, or 0.25, 0.50, 1 and 2 mg l(-1) Cu for 14 days, respectively, then tolerance index (TI) and EC50 (the concentrations of metals in solutions which reduce 50% of normal root growth) were calculated. The results indicated that both Lechang and Fankou populations of the two grasses showed a greater tolerance to the three metals than those growing on the uncontaminated area, which suggested that co-tolerant ecotypes have evolved in the two grasses. P. distichum collected from Fankou tailings had the highest tolerance to Cu while Lechang population the highest tolerance to Pb and Zn among the tested populations, and tolerance levels in P. distichum were related to metal concentrations in the plants. P. distichum had a better growth performance than C. dactylon when both of them were grown on the tailings sites. Tolerant populations of these species would serve as potential candidates for re-vegetation of wastelands contaminated with Pb, Zn and Cu.

Biodegradation, Environmental↗
PubMed1987

Cosmetic intolerance.

A study of cosmetic intolerance has been undertaken in 5202 patients tested for possible contact dermatitis. Each patient has been evaluated by medical history and patch testing. Intolerance to cosmetics involved only 5.9% of the total population tested. If other possible sources of allergens (medication, occupation, hobbies etc) are associated, this figure rises to 11.7%. The origin of the cosmetic intolerance is more often an allergy than irritation. Soaps and shampoos are the most important types of cosmetics responsible for adverse reactions. The principal allergens are the fragrances, preservatives, hair dyes and the patients' own products. In this last category, the specific allergen has not always been detected.

Adult↗
PubMed1979

Genetic distances among the five tribal populations of Andhra, Pradesh, South India.

In this paper, data on genetic distances among five tribal populations ae given. Among the five tribes, Koya Dora, Raj Gond and Naikpod are autochthonous populations of the Deccan plateau whereas the other two groups, Pardhan and Lambadi are migrants. Kova Doras were sampled from five distant localities. Genetic markers typed are: A1A2B0, Rho(D) blood group systems glucose-6-phosphate dehydrogenase deficiency, transferrin, haptoglobin, groupspecific component, haemoglobin, colour-vision deficiency and tastability to P. T. C. Using frequency data for the above nine genetic loci, genetic distances between the five endogamous tribes, and between the five groups of Koya Dora are calculated by adopting the statistical method of Edwards (1971). While genetic distances between Koya Dora, Raj Gond and Lambadi are minimal, the genetic distance between Pardhans and other tribal groups is maximum. Naikpods occupy an intermediate position. The closeness of Lambadi with Koya Dora and RAJ Gond can be regarded as coincidental. Interestingly, the differences in the genetic distance values between five Koya Dora groups are as great as the differences between the five endogamous tribal populations tested for the same loci. Genetic affinities of these tribal populations are discussed in relation to their ethnic origin migration and geographical isolation.

Adult↗
PubMed1997

Distribution of types for six PCR-based loci; LDLR, GYPA, HBGG, D7S8, GC and HLA-DQA1 in central Pyrenees and Teruel (Spain).

The PCR-based DNA loci LDLR, GYPA, HBGG, D7S8, GC and HLA DQA1 are widely used in forensic casework analyses. Population data on the distribution of allele frequencies are desired to estimate the rarity of a DNA profile. We studied the allele distributions at these forensically important DNA markers in two Spanish populations (Central Pyrenees and Teruel). Results were in agreement with Hardy-Weinberg expectations. Furthermore, there was little evidence for departures from expectation of independence between loci within the two sample populations. Tests for homogeneity were carried out between the two Spanish populations and a U.S. Caucasian population.

Alleles↗
PubMed2004

Application of a prediction model for identification of individuals at diabetic risk.

As a follow-up to our preceding paper, we attempted to extract features of health risk progression for diabetes in Sequential Multi Layered Perceptron (SMLP) via inverse processing of the learned structure. The time-varying risk progress was assessed with risk trajectory and conditional mixture model. Overall risk cut along with the prediction was stable over time and high body mass index (BMI) tops the health behavioral risks predicting the onset of diabetes. For the initial prediction, high BMI (obesity), high blood pressure (BP), high cholesterol, and diet in fatty food were significant. Over time, variations in trajectory were due to changes in BMI, stress, BP, cholesterol, and fatty food intake. We tested the effectiveness of identifying prediabetics by the SMLP by applying the implemented SMLP to a test population of employees from a large manufacturing company, where an early worksite health promotion was initiated (1984). This resulted in a potential sensitivity (71.4%) although there were issues like mapping corresponding risks and large time lags. A secondary test on the similar population as in the previous paper showed a promising sensitivity (86.5%) over 3 years. When combining with targeted screening such as impaired glucose tolerance test only for those predicted to be diabetics, the presented prediction model and extracted features can be used in implementing an effective disease prevention and management program.

Diabetes Mellitus, Type 2↗
PubMed1996

Distribution and frequency of a polymorphic Alu insertion at the plasminogen activator locus in humans.

We have investigated the frequency distribution, across a broad range of geographically dispersed populations, of alleles of the polymorphic Alu insertion that occurs within the 8th intron of the tissue plasminogen, activator gene (PLAT). This Alu is a member of a recently derived subfamily of Alu elements that has been expanding during human evolution and continues to be transpositionally active. We used a "population tube" approach to screen 10 chromosomes from each of 19 human populations for presence or absence of this Alu in the PLAT locus and found that all tested populations are dimorphic for presence/absence of this insertion. We show that the previously published EcoRI, HincII, PstI, TaqI, and XmnI polymorphisms at the PLAT locus all result from insertion of this Alu and we use both restriction fragment length polymorphism and polymerase chain reaction analysis to examine the frequency of Alu(+) and Alu(-) alleles in a sample of 1003 individuals from 27 human populations and in 38 nonhuman primates. Nonhuman primates are monomorphic for the Alu(-) allele. Human populations differ substantially in allele frequency, and in several populations both alleles are common. Our results date the insertion event prior to the spread and diversification of modern humans.

Base Sequence↗
PubMed1998

Gestational diabetes: do lean young caucasian women need to be tested?

OBJECTIVE: The American Diabetes Association has recommended that pregnant women with low-risk factors need not be tested for gestational diabetes mellitus (GDM). The aim of this study was to determine the prevalence of GDM in women with low-risk factors and to see if the pregnancy outcomes of women with GDM from a low-risk group were different from the outcomes of other women with GDM. RESEARCH DESION AND METHODS: Over an 18-month period, all pregnant women were offered a test for GDM using a 75-g glucose tolerance test at the beginning of the 3rd trimester. GDM was diagnosed if the 2-h glucose level was > or =8.0 mmol/l. The prevalence of GDM was determined in women with defined low-risk factors (Caucasian ethnic origin, age <25 years, and BMI <25 kg/m2). The pregnancy outcomes of women with GDM from a low-risk group were compared with those of other women with GDM. RESULTS: From a tested population of 2,907 women, 573 were identified as coming from a low-risk group. The prevalence of GDM in this low-risk group was 2.8%. The pregnancy outcomes of women with GDM from a low-risk group were no different from the pregnancy outcomes of other women with GDM, with respect to frequency of insulin use, units of insulin per day, morbidity, emergency caesarian section, and the percentage of both large- and small-for-gestational-age babies. In our population, if low-risk women were excluded, 80% of women would still require testing and nearly 10% of all cases of GDM would be missed. CONCLUSIONS: Women from a low-risk group have a 2.8% prevalence rate of GDM. The pregnancy outcomes of women with GDM from a low-risk group are similar to the outcomes of other women with GDM. Concerning the use of the 75-g glucose tolerance test in pregnancy, the recommendation not to test women from a low-risk group requires further evaluation in different populations before it can be endorsed.

Adult↗
PubMed2004

Excito-repellency of deltamethrin on the malaria vectors, Anopheles minimus, Anopheles dirus, Anopheles swadiwongporni, and Anopheles maculatus, in Thailand.

This study compared the behavioral avoidance responses of 4 mosquito malaria vectors, Anopheles minimus, Anopheles dirus, Anopheles maculatus form B, and Anopheles swadiwongporni, to deltamethrin, the primary insecticide used for indoor residual spraying for malaria vector control in Thailand. Six test populations. representing 4 laboratory colonies and 2 wild-caught populations, were observed during and after exposure to deltamethrin at the operational dose (0.02 g active ingredient/m2) in excito-repellency escape chambers. The laboratory colonies included a deltamethrin-susceptible colony and a deltamethrin-resistant colony of An. minimus species A, 1 colony of An. dirus species B, and 1 colony of An. maculatus form B. The 2 wild-caught populations included An. swadiwongporni and members of the An. dirus complex. Times to escape by female mosquitoes during 30 min of exposure to deltamethrin-treated papers were observed in all populations and compared to nontreated paired controls in contact and noncontact test configurations. Strong behavioral avoidance was observed in the deltamethrin-resistant colony of An. minimus, followed by An. swadiwongporni and An. maculatus. The slowest escape response was observed in the colony of An. dirus species B. All 6 populations of Anopheles showed marked contact irritancy to deltamethrin compared to paired controls and noncontact repellency trials, in both controlled laboratory colonies and field-caught populations. The degree of repellency was less profound than irritancy but, in most cases, produced a significant escape response compared to paired controls. Avoidance behavior appears to be an innate behavior of mosquitoes, as indicated by the general avoidance response detected in all 4 species, regardless of deltamethrin susceptibility status, age, or nutritional and physiological status. Excito-repellency assays of the type described in this study should become an integral part of the overall assessment of an insecticide's ability to control disease transmission in any given area.

Animals↗
PubMed1996

Toward localization of the Werner syndrome gene by linkage disequilibrium and ancestral haplotyping: lessons learned from analysis of 35 chromosome 8p11.1-21.1 markers.

Werner syndrome (WS) is an autosomal recessive disorder characterized by premature onset of a number of age-related diseases. The gene for WS, WRN, has been mapped to the 8p 11.1-21.1 region with further localization through linkage disequilibrium mapping. Here we present the results of linkage disequilibrium and ancestral haplotype analyses of 35 markers to further refine the location of WRN. We identified an interval in this region in which 14 of 18 markers tested show significant evidence of linkage disequilibrium in at least one of the two populations tested. Analysis of extended and partial haplotypes covering 21 of the markers studied supports the existence of both obligate and probable ancestral recombinant events which localize WRN almost certainly to the interval between D8S2196 and D8S2186, and most likely to the narrower interval between D8S2168 and D8S2186. These haplotype analyses also suggest that there are multiple WRN mutations in each of the two populations under study. We also present a comparison of approaches to performing disequilibrium tests with multiallelic markers, and show that some commonly used approximations for such tests perform poorly in comparison to exact probability tests. Finally, we discuss some of the difficulties introduced by the high mutation rate at microsatellite markers which influence our ability to use ancestral haplotype analysis to localize disease genes.

Age of Onset↗
PubMed1996

Nitrate contamination of drinking water: relationship with HPRT variant frequency in lymphocyte DNA and urinary excretion of N-nitrosamines.

We studied peripheral lymphocyte HPRT variant frequency and endogenous nitrosation in human populations exposed to various nitrate levels in their drinking water. Four test populations of women volunteers were compared. Low and medium tap water nitrate exposure groups (14 and 21 subjects) were using public water supplies with nitrate levels of 0.02 and 17.5 mg/l, respectively. Medium and high well water nitrate exposure groups (6 and 9 subjects) were using private water wells with mean nitrate levels of 25 and 135 mg/l, respectively. Higher nitrate intake by drinking water consumption resulted in a dose-dependent increase in 24-hr urinary nitrate excretion and in increased salivary nitrate and nitrite levels. The mean log variant frequency of peripheral lymphocytes was significantly higher in the medium well water exposure group than in the low and medium tap water exposure groups. An inverse correlation between peripheral lymphocyte labeling index and nitrate concentration of drinking water was observed. Analysis of N-nitrosamine in the urine of 22 subjects by gas chromatography-mass spectrometry revealed the presence of N-nitrosopyrrolidine in 18 subjects. Analysis of the mutagenicity of well water samples showed that a small number of the well water samples were mutagenic in the Ames Salmonella typhimurium test after concentration over XAD-2 resin. In conclusion, consumption of drinking water, especially well water, with high nitrate levels can imply a genotoxic risk for humans as indicated by increased HPRT variant frequencies and by endogenous formation of carcinogenic N-nitroso compounds from nitrate-derived nitrite.

Female↗
PubMed2002

Origin and affinities of indigenous Siberian populations as revealed by HLA class II gene frequencies.

Gene frequencies of eight Siberian populations (Mansi, Tuva, Todja, Tofalar, Buryat, Okhotsk Evenki, Ulchi, and Negidal) were determined for the three most polymorphic HLA class II loci ( DRB1, DQA1, and DQB1) by a combination of single-stranded conformational polymorphism typing and DNA sequencing. The number of alleles per population ranged from 16 to 25, from seven to eight, and from nine to 14 for the DRB1, DQA1, and DQB1 loci, respectively. The alleles at the three loci occurred in 66 different combinations (haplotypes), most of which appeared to be of ancient origin, but some may have arisen within the Siberian populations. Phylogenetic analysis of the frequency data suggests that the HLA genes of Asian and indigenous American populations stem from a single pool distinct from the gene pools of European and African populations. The Asian populations separate into two clusters, one of which encompasses nearly all the Siberian populations and all the indigenous American populations tested, while the other consists of Central, Eastern, and Southeastern Asian populations. The position of the Tuva people appears to be near the node from which the two clusters diverge. The divergence time of the two clusters is estimated to be 21,000-24,000 years BP. Three different branches of the native Siberian peoples seem to have contributed founders for the indigenous American ethnic groups.

Alleles↗
PubMed1978

Cytotoxicity of synthetic fuel products on Tetrahymena pyriformis. II. Shale oil retort water.

Shale oil retort water is obtained by centrifuging the oil/water emulsion produced by oil shale retorting. The ciliate Tetrahymena pyriformis was exposed to retort water; 2, 1, and 0.5% initially increased motility; longer exposures decreased motility. Three, 4, and 5% all decreased motility. Cell lysis was directly related to concentration; after 24 h, population densities were 0, 10, and 25% of controls for 2, 1, and 0.5% retort water, respectively. Oxygen consumption paralleled the motility pattern: at lower concentrations it increased initially but decreased with extended exposures while at higher concentrations it decreased rapidly. The most striking cytologic alteration of cells exposed to the toxicant occurred in the membranes; alterations of mucocysts and glycogen content were also observed, but mitochondrial changes were not. Population growth was affected at much lower concentrations than the other test indices. The growth of test populations reached a plateau at values inversely related to concentration: concentrations less than 0.4% had no effect on growth rate.

Animals↗
PubMed1988

Polymorphic acetylation of sulphamethazine in a Zimbabwe population.

Sulphamethazine, 8 mg/kg body weight, was administered orally in tablet form to 100 healthy volunteers and total and free sulphamethazine were determined in the six hour urine sample. The bimodal population frequency distribution for percentage acetylated sulphamethazine showed 42 of the tested population to be fast and 58 to be slow acetylators, that is, an estimation of q = 0.72 +/- 0.3 as the frequency of the allele controlling slow acetylation. The study also revealed ample evidence that the assay of the drug in urine can be done in a significantly shorter time.

Acetylation↗
PubMed1981

Application of information theory to clinical diagnostic testing. The electrocardiographic stress test.

The inherent imperfection of clinical diagnostic tests introduces uncertainty into their interpretation. The magnitude of diagnostic uncertainty after any test may be quantified by information theory. THe information content of the electrocardiographic ST-segment response to exercise, relative to the diagnosis of angiographic coronary artery disease, was determined using literature-based pooled estimates of the true- and false-positive rates for various magnitudes of ST depression from less than 0.5 mm to greater than or equal to 2.5 mm. This analysis allows three conclusions of clinical relevance. First, the diagnostic information content of exercise-induced ST-segment depression, interpreted by the standard 1.0-mm criterion, averages only 15% of that of coronary angiography. Second, there is a 41% increase in information content when the specific magnitude of ST-segment depression is analyzed, as opposed to the single, categorical 1-mm criterion. Third, the information obtained from ECG stress testing is markedly influenced by the prevalence of disease in the population tested, being low in the asymptomatic and typical angina groups and substantially greater in groups with nonanginal chest pain and atypical angina. The quantitation of information has broad relevance to selection and use of diagnostic tests, because one can analyze objectively the value of different interpretation criteria, compare one test with another and evaluate the cost-effectiveness of both a single test and potential testing combination.

Electrocardiography↗
PubMed1985

Mathematical models of the effectiveness and persistence of mosquito repellents.

Two models of the effectiveness and persistence of mosquito repellents on the skin were developed from published functions and data. The probit plane model, Y = a + b1X1 + b2X2, relates the response (Y, in probits) of the mosquito test population to the log dose (X1) of repellent applied and the test period, or elapsed time from the time of application (X2). The exponential decay model, Z = X1 + (b2/b1)X2, estimates the repellent residue (log-1 Z) from X1 and X2. The models were validated with original data from tests of deet (N,N-diethyl-3-methylbenzamide) and ethyl hexanediol (2-ethyl-1,3-hexanediol) on the forearm against the yellow fever mosquito, Aedes aegypti. The probit plane model was evaluated as Y = 8.83 + 1.56 X1-0.69X2 for deet and Y = 8.67 + 1.68X1 - 0.92X2 for ethyl hexanediol when X1 is in log mg/cm2 and X2 is in hours. The exponential decay model was evaluated as Z = X1 - 0.45X2 for deet and Z = X1 - 0.55X2 for ethyl hexanediol. The decay constant (lambda) and half-life (t1/2) were estimated as 1.03 hr-1 and 0.67 hr for deet and 1.26 hr-1 and 0.55 hr for ethyl hexanediol from the slope parameter (b2/b1) of the decay model. Applicable correlation coefficients, standard errors and confidence limits are given. The introduction of these models of the pharmacodynamics of mosquito repellents is a step toward establishing a rational basis for the research, development, testing and evaluation of repellents and for their regulation by the government.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1996

Effect of off-site transportation on detection of Neisseria gonorrhoeae in endocervical specimens.

OBJECTIVES: To evaluate both the effect of off-site transportation on detection of Neisseria gonorrhoeae in cultured endocervical specimens and the impact of transportation on viability of N. gonorrhoeae by comparison of culture with a nucleic acid probe assay. DESIGN: Three endocervical swabs were randomly collected; one was tested on-site using a nucleic acid-based assay (PACE 2NG System, Gen-Probe, Inc, San Diego, Calif), one was tested off-site following inoculation to modified Thayer-Martin agar (Remel, Lenexa, Kan), and a third swab was tested on-site by culture isolation. A nucleic acid amplification assay of the original swab for PACE 2NG testing was used to resolve discrepancies. SETTING: The emergency department of a university medical center. PATIENTS: Four hundred two patients were evaluated. The test population consisted of both asymptomatic and symptomatic patients. MAIN OUTCOME MEASURE: Positivity for N. gonorrhoeae by one or more of the test procedures, with discrepancy analysis when warranted. RESULTS: Of 402 specimens evaluated, the sensitivities for on-site and off-site testing using culture isolation for N. gonorrhoeae were 88.9% and 77.8%, respectively, in a population prevalence of 6.7%. However, the sensitivity for on-site PACE 2NG testing for N. gonorrhoeae was 96.3%. CONCLUSIONS: A decrease in sensitivity between on-site and off-site culture was found, which suggested transportation may have an adverse effect on the detection of N gonorrhoeae. However, with the limited population and prevalence, the difference was not found to be statistically significant. Further studies indicated that the nucleic acid probe assay was significantly more sensitive (P = .05) when compared with off-site testing using a culture isolation method, demonstrating that viability is an important consideration. These results suggested that a molecular probe assay should be considered in testing specimens for N. gonorrhoeae, especially when the specimen is to be transported off-site.

Bacteriological Techniques↗
PubMed2006

Case-control association tests correcting for population stratification.

In case-control association studies unobserved population stratification may act as a confounder, leading to an increased number of false positive results. Methods accounting for population structure by using additional genetic markers broadly follow one of two concepts: Genomic Control (GC) and Structured Association (SA). While extending existing methods of Structured Association we show that it is necessary to incorporate phenotypic information when inferring population structure, otherwise a systematic bias is introduced. Moreover, for moderate population stratification a Wald test statistic should be preferred as a Structured Association test statistic in comparison to a likelihood ratio test. The introduced extensions are compared to existing methods of Structured Association, as well as to Genomic Control, in a simulation study which is based on realistic situations of large case-control studies with moderate population stratification. A disadvantage of Genomic Control turns out to be the large variation in estimating the variance inflation factor, as well as the power loss if population structure increases. We come to the overall conclusion that Structured Association, if applied correctly, is superior to Genomic Control, at least in the case of simple population structure as simulated here.

Case-Control Studies↗
PubMed1997

Randomized trials of sodium reduction: an overview.

We updated a previously published overview of randomized clinical trials testing the effects of reducing sodium intake. We excluded trials that had confounded designs, enrolled preadolescent study populations, tested intakes outside the usual range for the US population, or reported neither systolic nor diastolic blood pressure. Thirty-two trials with outcome data for 2635 subjects were included. Two reviewers abstracted information independently and differences were reconciled. Pooled blood pressure differences between treated and control groups were highly significant for all trials combined and for trials in hypertensive and normotensive subjects pooled separately. The effects on blood pressure of lowering sodium in hypertensive and normotensive subjects, respectively (each trial weighted according to sample size), were -4.8/-2.5 and -1.9/-1.1 mm Hg (systolic/diastolic). Median differences in sodium excretion between sodium-reduction and control groups in these subgroups were -77 and -76 mmol/24 h, respectively. Weighted linear-regression analyses across the trials showed dose responses, which were more consistent for trials in normotensive subjects. These associations were, per 100 mmol Na/24 h, -5.8/-2.5 and -2.3/-1.4 mm Hg in hypertensive and normotensive subjects, respectively. There is no evidence that sodium reduction as achieved in these trials presents any safety hazards. The blood pressure reduction that would result from a substantial lowering of dietary sodium in the US population could reduce cardiovascular morbidity and mortality.

Blood Pressure↗