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PubMed2003

Use of mammography screening among older Samoan women in Los Angeles county: a diffusion network approach.

Minority migrant populations, such as older Samoan women, are likely to underuse preventive health services, including mammography screening. The purpose of this paper is to explore how informal (lay peers from churches) and formal (health care providers) health communication networks influence mammography screening use among older Samoan women. To do so, we apply diffusion of innovation theory and network analysis to understand how interpersonal networks may affect mammography use in this urban-dwelling, migrant population. The data come from a survey of 260 Samoan women, aged 50 years or older, who attended 39 randomly sampled Samoan churches in Los Angeles County (USA) between 1996 and 1997. Retrospective data, based over a 20-year period from this sample's year of first use of mammography screening, suggest that interpersonal networks may have accounted for the dramatic increase in the rate of adoption within the past 5 years of the survey. Using this information, we categorized women into mutually exclusive stages of mammography use and regressed these stages of mammography use on formal (had a provider referral) and informal (level of connectedness with peers in churches) health communication networks. The results indicated that being well-connected within women's informal, church-based health communication networks increased the likelihood of being in the decision (planned to have) and implementation and confirmation (had a recent mammogram) stages, but having a provider referral for a mammogram (formal networks) only increased the likelihood of being in the latter stages compared to women in the knowledge and persuasion stages. Formal and informal health communication networks influence recent use of mammography screening, but informal networks, in and of themselves, are also influential on future intention to use mammography screening.

Aged↗
PubMed1988

Microfilaria density distribution in the human population and its infectivity index for the mosquito population.

A new method of computing the infectivity index of microfilariae (mf) for the mosquito population is proposed using the estimated mf density distribution in the human population. the observed density distribution is considered a compound of the Poisson and the gamma distributions. The former distribution describes the probability of a specimen containing a specified number of mf and the latter describes the density distribution of mf in the host population. The mf infectivity index is the probability that a blood meal will include at least 1 mf, conditional on the population-density distribution of mf as specified by the gamma distribution. Actual data indicate that this population-density-based infectivity index can be considerably different from the conventional index based on the survey-density distribution. The level of the carrier rate of mf in a survey is greatly influenced, apart from the sample variation, by the average volume of blood taken from each person. The rate computed on the estimated population-density distribution of mf is convertible to any base amount of blood.

Animals↗
PubMed1992

A nonpromoting phorbol from the samoan medicinal plant Homalanthus nutans inhibits cell killing by HIV-1.

Extracts of Homalanthus nutans, a plant used in Samoan herbal medicine, exhibited potent activity in an in vitro, tetrazolium-based assay which detects the inhibition of the cytopathic effects of human immunodeficiency virus (HIV-1). The active constituent was identified as prostratin, a relatively polar 12-deoxyphorbol ester. Noncytotoxic concentrations of prostratin from greater than or equal to 0.1 to greater than 25 microM protected T-lymphoblastoid CEM-SS and C-8166 cells from the killing effects of HIV-1. Cytoprotective concentrations of prostratin greater than or equal to 1 microM essentially stopped virus reproduction in these cell lines, as well as in the human monocytic cell line U937 and in freshly isolated human monocyte/macrophage cultures. Prostratin bound to and activated protein kinase C in vitro in CEM-SS cells and elicited other biochemical effects typical of phorbol esters in C3H10T1/2 cells; however, the compound does not appear to be a tumor promoter. In skin of CD-1 mice, high doses of prostratin induced ornithine decarboxylase only to 25-30% of the levels induced by typical phorbol esters at doses 1/30 or less than that used for prostratin, produced kinetics of edema formation characteristic of the nonpromoting 12-deoxyphorbol 13-phenylacetate, and failed to induce the acute or chronic hyperplasias typically caused by tumor-promoting phorbols at doses of 1/100 or less than that used for prostratin.

Animals↗
PubMed1994

Structure elucidation of three triterpenoid saponins from Alphitonia zizyphoides using 2D NMR techniques.

High-field nmr experiments have been used to determine the structures of three new saponins, zizyphoisides C, D, and E [1-3], isolated from Alphitonia zizyphoides, a medicinal plant found in the Samoan rain forest. The saponins consist of the aglycone, jujubogenin, to which are attached three sugar units and an unsaturated side-chain. The three compounds are similar except for the location of an acetyl group on one of the sugar units.

Carbohydrate Sequence↗
PubMed1993

T cell receptor polymorphisms in Caucasians and Polynesians.

The purpose of this study was to find genetic polymorphisms that might be useful in studies of Polynesian-Caucasian racial admixture and Polynesian disease susceptibility. The allele frequencies of six T cell receptor locus RFLP were measured in 73 Caucasians and two Polynesian ethnic groups comprising 86 Maoris and 95 Samoans. The RFLP studied were (locus/enzyme/probe): C alpha/Taq1/Y14, V alpha/Taq1/Y14, C beta/BglII/Y35, C gamma/Pvu II/HGP02, V beta 7/BamHI/V beta 7.4 and V beta 8/Bam HI/V beta 8.1. Racial differences in allele frequency were present with all six RFLP (P < 0.001). The allele frequencies of the V alpha/Taq1/Y14 and the V beta 7/BamHI/7.4 RFLP were similar in the two Polynesian groups, both of which differed from the Caucasians. The 1.4 kb allele of the V alpha/Taq1/Y14 RFLP and the 8.0 kb allele of the V beta 7/BamHI/7.4 RFLP were present in low frequency in both Polynesian groups compared to the Caucasian group, consistent with a gene flow effect. These alleles may be useful in studies of Caucasian-Polynesian racial admixture.

Adolescent↗
PubMed2026

The Soifua Manuia reference panel with 2,570 Samoan haplotypes improves genotype imputation quality among Samoans.

Genotype imputation is fundamental to association studies, and yet even gold standard panels like TOPMed are limited in the populations for which they yield good imputation. Specifically, Pacific Islanders are poorly represented in extant panels. To address this, we used whole-genome sequencing from 1,285 Samoan individuals combined with 1000 Genomes Project (1KGP) individuals to construct an imputation reference panel that better represents Pacific Islander, specifically Samoan, genetic variation. Here we show that this panel yielded up to two times more well-imputed (r2&#x2009;&#x2265;&#x2009;0.80) variants than TOPMed-R3 and 1KGP and was enriched for moderate and high impact variants. There was improved imputation accuracy across the minor allele frequency (MAF) spectrum; accuracy (r2) was greater for population-specific variants (high fixation index, FST) and those from larger haplotypes (high LD score). However, the gain in accuracy over TOPMed-R3 was largest for small haplotypes, reflecting the Samoan panel's ability to capture variation not well tagged by other panels.

Haplotypes↗
PubMed2001

A nutrition and exercise intervention program for controlling weight in Samoan communities in New Zealand.

OBJECTIVE: To promote weight loss in Samoan church communities through an exercise program and nutrition education. METHODS: A quasi-experimental design was used to assess weight change, over 1 y, in cohorts of people aged 20-77 y from three non-randomised Samoan church communities (two intervention, n=365 and one control, n=106) in Auckland, New Zealand. The intervention churches received aerobics sessions and nutrition education about dietary fat. RESULTS: Baseline body mass index for the intervention and control churches was (mean+/-s.e.) 34.8+/-0.4 and 34.3+/-0.9 kg/m(2), respectively. The intervention churches lost an average of 0.4+/-0.3 kg compared to a 1.3+/-0.6 kg weight gain in the control church (P=0.039, adjusted for confounders). The number of people who were vigorously active increased by 10% in the intervention churches compared to a 5% decline in the control church (P=0.007). Nutrition education had little apparent impact on knowledge or behaviour. CONCLUSION: Samoan communities in New Zealand are very obese and have high rates of annual weight gain. A community-based intervention program arrested this weight gain in the short term.

Adult↗
PubMed1999

Acidic isoforms of chorionic gonadotrophin in European and Samoan women are associated with hyperemesis gravidarum and may be thyrotrophic.

OBJECTIVE: There is conflicting evidence concerning the role of human chorionic gonadotrophin (hCG) in the aetiology of hyperemesis gravidarum (HG); particular isoforms of hCG may be the critical factor. Ethnic differences in HG prevalence and putative thyrotrophic effects of hCG may also relate to differences in hCG isoform profiles. To address these issues we examined the relationship of hCG isoforms to HG and thyroid function tests in two groups of women from ethnic backgrounds with significantly different HG prevalence rates. PATIENTS AND DESIGN: We enrolled 10 European and 10 Samoan women with HG and an equally sized non-hyperemetic, gestational stage matched control group. MEASUREMENTS: We administered a questionnaire, generated serum hCG charge-isoform profiles by chromatofocusing and measured the serum concentrations of total hCG, oestradiol (E2), thyrotrophin (TSH) and free thyroxine (FT4). RESULTS: The mean serum total hCG levels were highest in the Samoan hyperemetics (176,268 IU/l), and overall higher in hyperemetics compared with controls (159,770 IU/l vs. 86,420 IU/l, P < 0.001). When compared with controls, hyperemetics displayed increased hCG concentrations in the more acidic half (pH < 4) of the chromatofocusing pH range (89,843 IU/l vs. 41,146 IU/l, P < 0.003). Serum E2 levels did not differ between the four groups, but correlated with the hCG concentration between pH 5.2 and 4.01. Mean serum TSH levels were significantly lower in hyperemetics than in controls (0.33 mIU/l vs. 1.19 mIU/l, P < 0.001) and correlated with the hCG concentration between pH 4.6 and 2.8, while serum FT4 correlated with the hCG concentration below pH 4.0. CONCLUSIONS: Acidic isoforms of hCG may play a role in the aetiology of HG and gestational thyrotoxicosis. Minor ethnic differences in hCG isoform profiles were observed, but the relationship of acidic hCG isoforms to HG and serum thyroid hormone levels was largely independent of the patients' ethnicity. The mechanisms by which acidic isoforms might provoke nausea remain uncertain, but do not seem to involve E2, while the longer half-life of acidic hCG isoforms may result in increased in vivo TSH receptor cross-talk with resultant thyrotrophic effects.

Adult↗
PubMed1998

Measuring departures from Hardy-Weinberg: a Markov chain Monte Carlo method for estimating the inbreeding coefficient.

Many well-established statistical methods in genetics were developed in a climate of severe constraints on computational power. Recent advances in simulation methodology now bring modern, flexible statistical methods within the reach of scientists having access to a desktop workstation. We illustrate the potential advantages now available by considering the problem of assessing departures from Hardy-Weinberg (HW) equilibrium. Several hypothesis tests of HW have been established, as well as a variety of point estimation methods for the parameter which measures departures from HW under the inbreeding model. We propose a computational, Bayesian method for assessing departures from HW, which has a number of important advantages over existing approaches. The method incorporates the effects-of uncertainty about the nuisance parameters--the allele frequencies--as well as the boundary constraints on f (which are functions of the nuisance parameters). Results are naturally presented visually, exploiting the graphics capabilities of modern computer environments to allow straightforward interpretation. Perhaps most importantly, the method is founded on a flexible, likelihood-based modelling framework, which can incorporate the inbreeding model if appropriate, but also allows the assumptions of the model to he investigated and, if necessary, relaxed. Under appropriate conditions, information can be shared across loci and, possibly, across populations, leading to more precise estimation. The advantages of the method are illustrated by application both to simulated data and to data analysed by alternative methods in the recent literature.

Algorithms↗
PubMed1999

Changing pregnancy outcomes of Samoan women in Hawaii.

In the state of Hawaii, Samoan mothers are known for the large average birthweight and low percentage of low birthweight (< 2500 g) of their infants, in spite of the relatively low socio-economic status of the population. This paper reports the findings of a temporal trend analysis of birth outcomes of Samoan women and identifies worrying changes. Data were obtained from Hawaii birth certificates. Single live births to Hawaii-resident Samoan and Caucasian women from 1979 to 1994 were included in the study. Infants of Samoan women experienced a 75 g decline in mean birthweight and an increase in the percentage of low (< 2500 g) and very low (< 1500 g) birthweight from 2.6 and 0.4 to 3.8 and 0.8 respectively. During the same time, infants of Caucasian mothers experienced an increase in mean birthweight and a decline in low birthweight, while very low birthweight did not change. Maternal socio-demographic characteristics explained only part of the findings and use of prenatal care did not appear to be associated with any birth outcome indicators. Multiple regression analyses identified an adjusted loss of 50.8 g in birthweight and a 1.48 increase in the odds ratio of small-for-gestational-age associated with birth at the end (1991-4) compared with the beginning (1979-82) of the study period. Further studies focusing on maternal health status and psycho-social variables, including the effect of acculturation-related stress, are warranted to identify at least some of the determinants of the changes identified by this analysis.

Adolescent↗
PubMed1998

Flavan-3-ols isolated from some medicinal plants inhibiting COX-1 and COX-2 catalysed prostaglandin biosynthesis.

Extracts from the four plant species Atuna racemosa Raf. ssp. racemosa, Syzygium corynocarpum (A. Gray) C. Muell., Syzygium malaccense (L.) Merr. & Perry and Vantanea peruviana Macbr., traditionally used for inflammatory conditions, were fractionated using a cyclooxygenase-1 catalysed prostaglandin biosynthesis in vitro assay. The flavan-3-ol derivatives (+)-catechin, (+)-gallocatechin, 4'-O-Me-ent-gallocatechin, ouratea-catechin and ouratea-proanthocynidin A were isolated as active principles. The IC50 values ranged from 3.3 microM to 138 microM whilst indomethacin under the same test conditions had an IC50 value of 1.1 microM. The flavonol rhamnosides mearnsitrin, myricitrin and quercitrin were also isolated. When further tested for inhibitory effect on cyclooxygenase-2 catalysed prostaglandin biosynthesis, the five flavan-3-ol derivatives exhibited from equal to weaker inhibitory potencies, as compared to their cyclooxygenase-1 inhibitory effects. The flavonol rhamnosides were inactive towards both enzymes.

Animals↗