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Biomedical subjects

K Hill

Publications and source records attributed to K Hill.

At least 55 records · Page 3Linked to original sources
PubMed2001

Every death counts: measurement of maternal mortality via a census.

Methods for measuring maternal mortality at national and subnational levels in the developing world lag far behind the demand for estimates. We evaluated use of the national population census as a means of measuring maternal mortality by assessing data from five countries (Benin, Islamic Republic of Iran, Lao People's Democratic Republic, Madagascar, and Zimbabwe) which identified maternal deaths in their censuses. Standard demographic methods were used to evaluate the completeness of reporting of adult female deaths and births in the year prior to the census. The results from these exercises were used to adjust the data. In four countries, the numbers of adult female deaths needed to be increased and three countries required upward adjustment of the numbers of recent births. The number of maternal deaths was increased by the same factor as that used for adult female deaths on the assumption that the proportion of adult female deaths due to maternal causes was correct. Age patterns of the various maternal mortality indicators were plausible and consistent with external sources of data for other populations. Our data suggest that under favourable conditions a national census is a feasible and promising approach for the measurement of maternal mortality. Moreover, use of the census circumvents several of the weaknesses of methods currently in use. However, it should also be noted that careful evaluation of the data and adjustment, if necessary, are essential. The public health community is urged to encourage governments to learn from the experience of these five countries and to place maternal mortality estimation in the hands of statistical agencies.

Censuses↗
PubMed2000

"It's a Wonderful Life". signaling generosity among the Ache of Paraguay.

Intensive food sharing among foragers and horticulturists is commonly explained as a means of reducing the risk of daily shortfalls, ensuring adequate daily consumption for all group members who actively pool resources. Consistently high food producers who give more than they receive, however, gain the least risk-reduction benefit from this daily pooling because they are the least likely to go without food on any given day. Why then do some high producers consistently share food, and why do some average producers share proportionally more food than others? We propose that although these individuals may not receive the same amounts they give (i.e., strict Tit-for-Tat), one explanation for their generosity is that they receive additional food during hard times. These include brief episodes of sickness, disease, injury, or accidents-fairly common events in traditional societies that can render individuals incapable of producing food, thereby having long-term effects on morbidity and fecundity and ultimately on lifetime reproductive success. Data collected among the Ache, a group of South American forager-horticulturists, indicate that those who shared and produced more than average (signaling cooperative intent and/or ability to produce) were rewarded with more food from more people when injured or sick than those who shared and produced below average. These results, framed within the context of tradeoffs between short-term and long-term fitness, may provide insight into motivations behind costly expenditures for establishing and reinforcing status and reputation.

Journal Article↗
PubMed2000

A Ca(2+)- and voltage-modulated flagellar ion channel is a component of the mechanoshock response in the unicellular green alga Spermatozopsis similis.

In flagellate green algae, behavioral responses to photo- and mechanoshock are induced by different external stimuli within 10-15 ms. In the accompanying changes in flagella beat, Ca(2+) has important regulatory roles. Although the axonemal Ca(2+) responsive elements are well characterized, analyses of flagellar channels involved in Ca(2+) signalling as well as other ion channels at the single-channel level were not yet conducted in green algae. To gain a further understanding of these important signaling elements in movement responses, intact flagella of Spermatozopsis similis were isolated and characterized and the solubilized flagellar membrane proteins were reconstituted into liposomes. We observed three types of channel activity, two of which were weakly anion and cation-selective and in the high-conductance regime typical for porin-like solute channels. The dominating channel activity was a voltage dependent, rectifying, low conductance (Lambda=80 pS in 50 mM KCl) cation-selective channel modulated by, and highly permeable to, Ca(2+) ions (SFC1: Spermatozopsis flagellar cation channel 1). Depolarizations necessary to activate SFC1 probably only occur in vivo during avoidance reactions of this alga. Ca(2+)-activation of SFC1 points to a direct link to Ca(2+)-mediated signaling pathway(s) in the flagella. Both the response to mechanoshock and SFC1 activity were inhibited by Gd(3+) and Ba(2+), thus supporting our assumption that SFC1 represents a major flagellar ion channel involved in this green algal avoidance reaction.

Algal Proteins↗
PubMed2000

Identification of the pore-forming region of the outer chloroplast envelope protein OEP16.

The chloroplast outer envelope protein OEP16 forms a cation-selective high conductance channel with permeability to amines and amino acids. The region of OEP16 directly involved in channel formation has been identified by electrophysiological analysis of a selection of reconstituted OEP16 mutants. Because analysis of these mutants depended on the use of recombinant protein, we evaluated the electrophysiological properties of OEP16 isolated directly from pea chloroplasts and of the recombinant protein produced in Escherichia coli. The results show that the basic properties like conductance, selectivity, and open probability of the channel formed by native pea OEP16 are comparable with the channel activity formed by the recombinant source of the protein. Following electrophysiological analysis of OEP16 mutants we found that point mutations and insertion of additional amino acid residues in the region of the putative helix 1 (Glu(73) to Val(91)) did not change the properties of the OEP16 channel. The only exception was a Cys(71)-->Ser mutation, which led to a loss of the CuCl(2) sensitivity of the channel. Analysis of N- and C-terminal deletion mutants of OEP16 and mutants containing defined shuffled domains indicated that the minimal continuous region of OEP16, which is able to form a channel in liposomes, lies in the first half of the protein between amino acid residues 21 and 93.

Amines↗
PubMed2000

Degradation of unassembled Vph1p reveals novel aspects of the yeast ER quality control system.

The endoplasmic reticulum quality control (ERQC) system retains and degrades soluble and membrane proteins that misfold or fail to assemble. Vph1p is the 100 kDa membrane subunit of the yeast Saccharomyces cerevisiae V-ATPase, which together with other subunits, assembles into the V-ATPase in the ER, requiring the ER resident protein Vma22p. In vma22Delta cells, Vph1p remains an integral membrane protein with wild-type topology in the ER membrane before undergoing a rapid and concerted degradation requiring neither vacuolar proteases nor transport to the Golgi. Failure to assemble targets Vph1p for degradation in a process involving ubiquitylation, the proteasome and cytosolic but not ER lumenal chaperones. Vph1p appears to possess the traits of a 'classical' ERQC substrate, yet novel characteristics are involved in its degradation: (i) UBC genes other than UBC6 and UBC7 are involved and (ii) components of the ERQC system identified to date (Der1p, Hrd1p/Der3p and Hrd3p) are not required. These data suggest that other ERQC components must exist to effect the degradation of Vph1p, perhaps comprising an alternative pathway.

Cytosol↗
PubMed2000

Specific requirement for the p85-p110alpha phosphatidylinositol 3-kinase during epidermal growth factor-stimulated actin nucleation in breast cancer cells.

We have studied the role of phosphatidylinositol 3-kinases (PI 3-kinases) in the regulation of the actin cytoskeleton in MTLn3 rat adenocarcinoma cells. Stimulation of MTLn3 cells with epidermal growth factor (EGF) induced a rapid increase in actin polymerization, with production of lamellipodia within 3 min. EGF-stimulated lamellipodia were blocked by 100 nM wortmannin, suggesting the involvement of a class Ia PI 3-kinase. MTLn3 cells contain equal amounts of p110alpha and p110beta, and do not contain p110delta. Injection of specific inhibitory antibodies to p110alpha induced cell rounding and blocked EGF-stimulated lamellipod extension, whereas control or anti-p110beta antibodies had no effect. In contrast, both antibodies inhibited EGF-stimulated DNA synthesis. An in situ assay for actin nucleation showed that EGF-stimulated formation of new barbed ends was blocked by injection of anti-p110alpha antibodies. In summary, the p110alpha isoform of PI 3-kinase is specifically required for EGF-stimulated actin nucleation during lamellipod extension in breast cancer cells.

Actins↗
PubMed2000

Lupus anticoagulant in a patient with parvovirus B19 infection.

We report the case of a patient who presented with a prodromal illness suggestive of viral infection, subsequently confirmed as parvovirus B19, who had a lupus anticoagulant present. Her IgG anti-cardiolipin antibody was normal (7.0 units/ml) but her IgM anti-cardiolipin was elevated (55 units/ml). These later returned to normal. Parvovirus B19 infection may be associated with the presence of lupus anticoagulant.

Adult↗
PubMed2000

[Volume-artifact reduction technique by spiral CT in the anterior, middle and posterior cranial fossae. Comparison with conventional cranial CT].

PURPOSE: The object of this study was to determine the extent to which a new volume-artifact reduction (VAR) modality using helical CT was able to reduce artifacts in the anterior, middle and posterior fossae in comparison with conventional CT (sequential mode). METHODS: In a prospective, randomized trial, 50 patients underwent helical CT (VAR) and 50 underwent sequential CT. The results were evaluated by three radiologists; influences on image quality where scaled between 1 (no artifact) and 4 (not assessable). Eight regions of the anterior, middle and posterior fossae were evaluated. RESULTS: On average, artifacts were scaled at 2.5 in helical CT (VAR) and 3.1 in conventional CT. Significant differences were seen at the eyeball, anterior to the petrosal bone, at the internal occipital crest, and at the level of the transverse sinus (p < 0.005). CONCLUSIONS: Helical CT with the VAR modality is superior to conventional, sequential CT in the area of the anterior, middle and posterior fossae.

Adolescent↗
PubMed2000

Pilot study of growth hormone administration during the refeeding of malnourished anorexia nervosa patients.

OBJECTIVE: In anorexia nervosa (AN), medical stabilization and nutritional repletion are pivotal steps toward physical and psychological recovery. Nutritional stabilization is often difficult in this patient group. Recombinant human growth hormone (rhGH) has been safely used as adjuvant therapy in other groups of malnourished patients. We hypothesize that rhGH treatment will hasten medical stabilization in AN patients. STUDY DESIGN: Fifteen patients admitted for inpatient treatment for AN, ages 12-18 years, were enrolled in a 28-day randomized, double-blind, placebo-controlled study. Patients received rhGH (0.05 mg/kg subcutaneously) or an equivalent volume of placebo daily. Outcome measures included time to reach medical/cardiovascular stability, rate of weight gain, and duration of hospitalization. All patients received a standard refeeding protocol. RESULTS: Mean admission body mass index was 14.5 kg/m2. The rhGH and placebo groups did not differ significantly in admission weight, BMI or daily caloric intake. Patients treated with rhGH reached medical/cardiovascular stability more rapidly than those treated with placebo (median 17 vs. 37 days, p = 0.02). Numerical but not statistically significant improvements were seen in weight gain and length of hospitalization in the rhGH group. CONCLUSION: Patients treated with rhGH achieved medical/cardiovascular stability more rapidly than those treated with placebo, and this, in turn, decreased the length of stay.

Adolescent↗
PubMed2000

An assessment of DHS maternal mortality indicators.

This study presents an assessment of the quality of data relating to maternal mortality collected in 14 Demographic and Health Surveys (DHS) for 13 countries that included a complete sibling history. Four aspects of data quality are considered: completeness of the data for reported events, evidence of omission in the reporting of events, plausibility of the pattern of sibling deaths, and sampling errors of the maternal mortality estimates. Although the data relating to reported events are complete for most variables, comparisons of sibling-history-based estimates of adult mortality for both males and females with other independent estimates suggest that sibling estimates are more likely to be underestimates than overestimates. The downward bias is probably greater for female mortality than for male mortality. The sampling errors associated with maternal mortality ratios are substantially larger than those associated with other frequently used DHS indicators. This lack of precision precludes the use of these data for trend analysis and has led to the recommendation that this DHS module not be used more than once every ten years in the same country.

Adolescent↗
PubMed2000

The effect of gender preference on contraceptive use and fertility in rural Egypt.

Data are used from two surveys of currently married women aged 15-44 conducted in 1979-80 and 1990-91 to explore the changing impact of gender preference on modern contraceptive use and on fertility in rural Menoufia, Egypt. The significantly positive effects on contraceptive use of having one or more sons in 1979 remained constant in 1990. Families without living sons had higher odds of having a birth than did families with two or more sons during 1979-80, and these relative odds were even higher in 1990-91 among families with three or more living children. The implications of these findings for subsequent declines in aggregate fertility are discussed.

Adolescent↗
PubMed2000

Prayer in medicine: a survey of primary care physicians.

Prayer and spirituality have been shown to have a significant impact on several health variables. Additionally, studies have shown that patients think prayer is important to their health. Very little research, however, has been done to determine primary care physicians' opinions regarding prayer and spirituality as it pertains to healthcare. We surveyed primary care physicians in Mississippi to assess their use of prayer in medical practice. Ninety-one percent of respondents considered prayer an important treatment modality, but 50.6% rarely or never discussed prayer with patients. Most who excluded prayer from clinical practice did so to avoid imposing their beliefs upon patients. A majority of primary care physicians in Mississippi recognize prayer as an important psychosocial variable in assessing and treating patients, but many are hesitant to incorporate this variable into the doctor-patient encounter.

Attitude of Health Personnel↗
PubMed1999

A rectifying ATP-regulated solute channel in the chloroplastic outer envelope from pea.

Phosphorylated carbohydrates are the main photoassimilated export products from chloroplasts that support the energy household and metabolism of the plant cell. Channels formed by the chloroplastic outer envelope protein OEP21 selectively facilitate the translocation of triosephosphate, 3-phosphoglycerate and phosphate, central intermediates in the source-sink relationship between the chloroplast and the cytosol. The anion selectivity and asymmetric transport properties of OEP21 are modulated by the ratio between ATP and triosephosphates, 3-phosphoglycerate and phosphate in the intermembrane space. Conditions that lead to export of triosephosphate from chloroplasts, i.e. photosynthesis, result in outward-rectifying OEP21 channels, while a high ATP to triosephosphate ratio, e.g. dark metabolism, leads to inward-rectifying OEP21 channels with a less pronounced anion selectivity. We conclude that solute exchange between plastids and cytosol can already be regulated at the level of the organellar outer membrane.

Adenosine Triphosphate↗
PubMed1999

Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase.

Mitochondrial preproteins are imported by a multisubunit translocase of the outer membrane (TOM), including receptor proteins and a general import pore. The central receptor Tom22 binds preproteins through both its cytosolic domain and its intermembrane space domain and is stably associated with the channel protein Tom40 (refs 11-13). Here we report the unexpected observation that a yeast strain can survive without Tom22, although it is strongly reduced in growth and the import of mitochondrial proteins. Tom22 is a multifunctional protein that is required for the higher-level organization of the TOM machinery. In the absence of Tom22, the translocase dissociates into core complexes, representing the basic import units, but lacks a tight control of channel gating. The single membrane anchor of Tom22 is required for a stable interaction between the core complexes, whereas its cytosolic domain serves as docking point for the peripheral receptors Tom20 and Tom70. Thus a preprotein translocase can combine receptor functions with distinct organizing roles in a multidomain protein.

Biological Transport↗
PubMed1999

Mortality in North Korean migrant households: a retrospective study.

BACKGROUND: A deteriorating economy, coupled with a series of natural disasters in 1995-97, led to a severe food crisis in North Korea. Although the country has received substantial international aid since 1996, demographic assessments of crisis impact have been limited. We assessed mortality trends in North Korea since 1995. METHODS: At 15 randomly selected sites in China, 440 North Korean adult migrants were interviewed during July-September, 1998. Respondents were asked about births, deaths, and migration patterns in their households between mid-1994 and mid-1998, and about household food sources. The respondents also provided basic demographic information about the households of their relatives. We compared mortality rates from migrant households with data from the 1993 census and with data about households of non-migrant relatives. FINDINGS: Households that included a recent migrant to China showed increasing mortality: crude death rates rose from 28.9 per 1000 in 1995, to 45.6 per 1000 in 1996, and to 56.0 per 1000 in 1997 (p=0.0001), with a 3-year average rate of 42.8 per 1000. The crude 3-year birth rate was 11.0 per 1000. Average household size declined from 4.0 at the beginning of 1995 to 3.4 at the end of 1997 (p=0.0002). Among 259 households of non-migrant relatives, the crude death rate was 43.2 per 1000 and the crude birth rate was 8.8 per 1000. In these households, the 3-year trend of increasing mortality was significant (p=0.001), as was the decline in average household size from 4.3 at the beginning of 1995 to 3.7 at the end of 1997 (p=0.0001). INTERPRETATION: Among North Korean households that include a recent migrant to China, mortality has increased and household size has declined since 1995. This trend raises concern about the state of the general population, at least in the province of North Hamkyong, from where most of the migrants originated.

Adolescent↗