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Biomedical subjects

L Hale

Publications and source records attributed to L Hale.

At least 19 recordsLinked to original sources
PubMed2005

Pregnancy spacing and maternal morbidity in Matlab, Bangladesh.

OBJECTIVE: The study examines the relationship between pregnancy spacing and seven measures of maternal morbidity in Matlab, Bangladesh. METHOD: The study analyzes maternal morbidity data on 11,122 women who visited a health center during their third trimester of pregnancy between 1996 and 2002. Adjusted odds ratios were obtained through logistic regression analysis to assess the effects of pregnancy intervals of differing lengths while holding constant other influences (six variables) on maternal morbidity. RESULTS: After controlling these variables, pre-eclampsia and high blood pressure are significantly more likely for women with preceding inter-pregnancy intervals of less than 6 months or 75 months or more compared to those with intervals of 27-50 months. Premature rupture of membranes is significantly more likely following inter-pregnancy intervals of 6-14 months, and edema is significantly more likely following inter-pregnancy intervals over 50 months. CONCLUSION: Short and long inter-pregnancy intervals are associated with increased incidence of some maternal morbidities.

Adult↗
PubMed2005

The Bristol cataract listing survey: profile of listed patients with visual acuity 6/12 or better.

INTRODUCTION: The aim of this study was to assess the vision-related quality of life (VR-QOL) in patients with good distance Snellen visual acuity (VA) who are listed for cataract surgery. METHODS: An observational cross-sectional prospective study of patients listed for cataract surgery. VA and VR-QOL data using the VCMI questionnaire were collected on patients attending preoperative assessment during June 2002. RESULTS: A total of 397 cataract patients were listed during this month. Following exclusions there were 378 eligible individuals, 210 (56%) of whom had a VA of 6/12 or better in the eye scheduled for surgery. Of these, 40% patients had only mild VR-QOL impairment. More than half of the patients with good VA (6/12 or better) in the surgery eye and mild VR-QOL impairment described their vision as poor in this eye. However, most of these patients were not dissatisfied with their overall level of vision. CONCLUSION: A significant number of patients listed for cataract surgery with VA of 6/12 or better had only mild VR-QOL impairment and were not dissatisfied with their overall level of vision. The decision to list a patient for surgery may have been based on the patient's perception of monocular vision rather than their quality of life.

Aged↗
PubMed2001

Use of thermal and vegetation index data from earth observing satellites to evaluate the risk of schistosomiasis in Bahia, Brazil.

A geographic information system (GIS) was constructed using maps of regional agroclimatic features, vegetation indices and earth surface temperature data from environmental satellites, together with Schistosoma mansoni prevalence records from 270 municipalities including snail host distributions in Bahia, Brazil to study the spatial and temporal dynamics of infection and to identify environmental factors that influence the distribution of schistosomiasis. In an initial analysis, population density and duration (months) of the annual dry period were shown to be important determinants of disease. In cooperation with the National Institute of Spatial Research in Brazil (INPE), day and night imagery data covering the state of Bahia were selected at approximately bimonthly intervals in 1994 (six day-night pairs) from the data archives of the advanced very high resolution radiometer (AVHRR) sensor of the National Oceanic and Atmospheric Administration (NOAA)-11 satellite. A composite mosaic of these images was created to produce maps of: (1) average values between 0 and +1 of the normalized difference vegetation index (NDVI); and (2) average diurnal temperature differences (dT) on a scale of values between 0 and 15 degrees C. For each municipality, NDVI and dT were calculated for a 3x3 pixel (9 km(2) area) grid and analyzed for relationships to prevalence of schistosomiasis. Results showed a statistically significant relationship of prevalence to dT (rho=-0.218) and NDVI (rho=0.384) at the 95% level of confidence by the Spearman rank correlation coefficient. Results support use of NDVI, dT, dry period climatic stress factors and human population density for development of a GIS environmental risk assessment model for schistosomiasis in Brazil.

Animals↗
PubMed2001

Effect of thymectomy on human peripheral blood T cell pools in myasthenia gravis.

The human thymus is required for establishment of the T cell pool in fetal life, but postnatal thymectomy does not lead to immunodeficiency in humans. Because thymectomy in humans is performed for treatment of myasthenia gravis (MG), we have studied patients with MG for effects of thymectomy on peripheral blood (PB) naive (CD45RA(+), CD62L(+)) and memory (CD45RO(+)) T cells. We have also determined the effect of thymectomy on levels of PB cells containing signal joint TCR delta excision circles (TRECs), a molecular marker of thymus emigrants that have divided few times after leaving the thymus. In 17 nonthymectomized and 26 thymectomized MG patients studied at varying times after thymectomy (1 day to 41 years), we found no significant mean difference in PB T cell TREC levels between ages 40 and 80 years. However, both thymectomized and nonthymectomized MG patients had lower PB T cell TREC levels than did age-matched normal subjects (p < 0.0001 for both). These data demonstrated that MG itself or treatment for MG decreased thymopoiesis independent of thymectomy. Next, to control for disease activity and treatment, we prospectively studied 10 MG patients before and from 27 to 517 days after thymectomy. We found that thymectomy decreased CD4 or CD8 T cell TREC concentrations most when thymopoiesis was active before thymectomy (six of six patients), but had little effect in patients when thymopoiesis was minimal (four of four patients). In contrast, there was no significant effect of thymectomy on absolute numbers of naive PB T cells. Thus, in MG, removal of a thymus with active thymopoiesis resulted in a significant fall in PB TREC(+) T cells postthymectomy.

Adolescent↗
PubMed2001

Embryo transfer: how to ensure correct placement in utero.

A review of current literature (1990-2000) was undertaken to identify factors that are important in the correct placement of embryos in utero. Although there are no absolute prerequisites, ultrasound monitoring to ensure correct catheter placement, pretreatment assessment of the cervical canal, minimization of trauma, avoidance of mucus and the use of a 'soft' catheter are all considered important factors in this process. Early patient mobilization after the transfer procedure has not been shown to influence the outcome. The establishment of a benchmark against which to evaluate individual performance and participation in 'refresher courses' if indicated will help to maximize the implantation rates of the assisted reproductive technology programme as a whole.

Embryo Transfer↗
PubMed2000

Targeting adolescent risk-taking behaviors: the contributions of egocentrism and sensation-seeking.

Tremendous resources are spent each year developing programs and messages targeting adolescent risk behavior. Adolescents are often reasonably well educated about methods for health promotion such as preventing HIV infection, yet they fail to act accordingly. One widely used individual difference variable, sensation-seeking, has been incorporated in health message design to some extent, but it fails to take development into account. Research on adolescent egocentrism suggests adolescents experience personal fable which can lead to an exaggerated sense of invulnerability. The present study sampled adolescents and college students to examine relative contributions of egocentrism and sensation-seeking to risk-taking behavior. Results indicate a latent factor labeled risk-seeking (primarily indicated by disinhibition and risk-taking personality, and to a lesser degree by invulnerability, experience-seeking, boredom susceptibility, and thrill and adventure-seeking) indeed predicted a latent factor labeled delinquent behavior (primarily indicated by alcohol consumption and delinquency, and to a lesser degree by drug use, drinking and driving, and risky driving). Other results indicate consistently high personal fable combined with high sensation-seeking explained most risk-taking behavior. Implications and directions for future research are discussed.

Adolescent↗
PubMed1999

Chromosome translocations in couples with in-vitro fertilization implantation failure.

Recurrent miscarriage is known to be associated with parental chromosomal abnormalities, particularly balanced reciprocal and Robertsonian translocations. The aim of this study was to test the hypothesis that couples with in-vitro fertilization (IVF) implantation failure, like those with recurrent miscarriage, have a higher than expected prevalence of translocations which may impact on pregnancy outcome. Patients who previously had at least 10 embryos transferred without achieving clinical pregnancy were evaluated for chromosome abnormalities as part of screening investigations for implantation failure. Recurrent miscarriage patients with a history of at least three consecutive first-trimester abortions were also tested. Results were compared to reports of infertility patients presenting for treatment and population neonatal screening programmes. Chromosomal abnormalities overall were detected in 13/514 individuals with implantation failure (2.5%), and 15/319 individuals with recurrent miscarriage (4. 7%). Translocations (reciprocal and Robertsonian) were found in 7/514 individuals (1.4%) and 7/219 couples (3.2%) with implantation failure (P < 0.0005 compared with infertile controls and P < 0.0001 compared with screened neonates). Translocations were found in 13/319 individuals (4.1%) and 12/130 couples (9.2%) with recurrent miscarriage. Balanced parental translocations may be implicated in the pathogenesis of IVF-implantation failure. Genetic evaluation should be considered as part of the investigation of these patients.

Adult↗
PubMed1998

Antibodies to beta2 glycoprotein I are associated with in vitro fertilization implantation failure as well as recurrent miscarriage: results of a prevalence study.

OBJECTIVE: To investigate whether antiphospholipid and related autoantibodies are associated with IVF implantation failure as well as with recurrent spontaneous miscarriage. DESIGN: Prevalence study. SETTING: University teaching hospital and associated IVF unit. PATIENT(S): Patients with at least three consecutive first-trimester miscarriages (n = 97), patients undergoing IVF who had at least 10 embryos transferred without any resulting clinical pregnancy (n = 105), fertile women (n = 106), and patients newly referred for IVF treatment (n = 52). INTERVENTION(S): Antibodies tested included lupus anticoagulant; immunoglobulin (Ig) G and IgM isotypes of each of anticardiolipin antibody, antiphosphatidylserine, antiphosphatidylethanolamine, and antiphosphatidylinositol; beta2 glycoprotein I antibodies; and antinuclear antibodies. Statistical analysis included chi2 and Fisher's exact tests for differences between groups, and multiple linear regression analysis and Spearman's nonparametric tests for relations between results. MAIN OUTCOME MEASURE(S): Seropositivity for autoantibodies tested. RESULT(S): Overall, 84 (23%) of the 360 samples tested positive for at least one autoantibody. Beta2 glycoprotein I IgM antibody and antinuclear antibody were significantly associated with both IVF implantation failure and recurrent miscarriage. CONCLUSION(S): Autoantibodies, particularly beta2 glycoprotein I antibodies and antinuclear antibodies, are associated with IVF implantation failure as well as with recurrent spontaneous abortion, although the mechanism is still unclear. The high seroprevalence of antibodies to beta2 glycoprotein I suggests that it may have an important role in autoimmune reproductive failure that needs to be explored further.

Abortion, Habitual↗
PubMed1996

Inhibition of estrogen-stimulated growth of uterine leiomyomas by selective estrogen receptor modulators.

Uterine leiomyoma is the most frequent gynecologic neoplasm in women. By using a panel of cell lines derived from spontaneous Eker rat leiomyomas, we examined the estrogen-responsive phenotype of these tumor cells. Leiomyoma-derived ELT cell lines proliferated in response to estrogen, and estrogen-induced cell proliferation could be inhibited by the estrogen antagonist ICI 182780 and the selective estrogen-receptor modulators (SERMs) raloxifene and tamoxifen. In addition to inhibiting cell growth, these antagonists also inhibited estrogen-induced increases in progesterone-receptor expression. These data indicate that SERMs such as raloxifene and tamoxifen act as estrogen antagonists in uterine myometrial cells and suggest that this class of compounds may be effective for treatment of this important gynecologic neoplasm.

Animals↗
PubMed1995

In vitro induction of primary, antigen-specific CTL from human peripheral blood mononuclear cells stimulated with synthetic peptides.

A protocol for in vitro induction of primary, antigen-specific CTL from human peripheral blood mononuclear cells (PBMCs) was developed. Antigen presenting cells (APCs) consisted of Staphylococcus aureus Cowan-I (SAC-I) activated PBMCs treated with a citrate-phosphate buffer at pH 3 to release endogenous peptides bound to surface MHC. This treatment resulted in transient expression of empty class I molecules which could be subsequently stabilized with peptide and beta 2-microglobulin (beta 2m). SAC-I activated PBMCs from HLA-A2.1 normal donors loaded with HBV core 18-27 peptide following acid treatment were used to stimulate PBMCs depleted of CD4+ T cells, in the presence of recombinant interleukin-7 (rIL-7). After 12 days, cells were restimulated with autologous, peptide-pulsed, adherent cells and tested for CTL activity 7 days later. In 23 independent experiments from 13 different HLA-A2.1 donors, this protocol resulted in induction of primary CTL more than 90% of the time. As indicated by both the frequency and magnitude of the response against peptide-sensitized target cells, SAC-I activated PBMCs treated with acid were the most efficient stimulator APC. Thirteen per cent of the cultures generated were capable of lysing target cells transfected with the HBV core antigen and, in general, these CTL cultures exhibited high avidity for the HBV core peptide. This protocol is generally applicable to different antigens and class I alleles, and thus, may be utilized to screen large numbers of peptides to identify human CTL epitopes.

Antigen-Presenting Cells↗
PubMed1984

Thymic stroma in AKR mice: its function and virus production.

This study reports experiments with thymic stromal remnants in AKR mice, a strain with a high natural incidence of thymic lymphoma. A method has been developed in which thymic stromal cells which survive a 4-week culture period, 1 week at 24 degrees C and 3 weeks at 37 degrees C are suitable for grafting. Most thymic lymphocytes die under these conditions. Stromal remnants were studied by culturing and grafting under the kidney capsule of 2-month-old syngeneic mice. Their in vitro morphology and virus production, their ability to reconstitute a new thymus from host progenitors and their eventual lymphoma development was evaluated. The stromal remnants were from: 1- and 3-month-old normal mice; 6-10-month-old normal mice; 21-28-day-old animals treated with the lymphomagenic virus, SL3-3, at 3 days of age. Our data show that thymic stromal function as measured by lymphoid reconstitution of thymic stromal grafts of AKR mice is not impaired with age or by the presence of oncogenic virus. Oncogenic viruses are found in the thymic stroma of old mice and in thymic stroma of young virus-treated mice. Oncogenic viruses are not found in thymic stroma of young normal mice. Lymphoma can develop in the grafted stromal remnants expressing lymphomagenic virus.

Animals↗
PubMed1982

Growth of normal hemopoietic cells in cultures of bone marrow from leukemic mice.

Bone marrow from mice with spontaneous leukemia was studied in long-term culture in the presence of 10(-7) M hydrocortisone. These conditions resulted in a complete loss of leukemia cells from marrows which initially showed 95% or greater replacement with lymphoblasts. The culture conditions were also found to favor the growth of hemopoietic stem cells and the surviving cultured cells produced sufficient numbers of these cells to protect lethally irradiated (950 rads) syngeneic mice. The irradiated recipients of the cultured marrow did not develop leukemia during the 180 days of observation post-irradiation, indicating the absence of leukemia cells in the inocula. A loss of leukemia cells in vitro occurred in cultures with and without the addition of hydrocortisone to the medium. Hydrocortisone was shown to have a stimulating effect on maintenance of hemopoietic stem cells, granulocyte progenitors and granulopoiesis in these cultures.

Animals↗
PubMed1980

AKR murine leukemia viruses and long-term bone marrow cultures from AKR and SJL mice.

We have evaluated the effects of AKR mouse retroviruses on a system of long-term bone marrow cultures which allows prolonged replication of hemopoietic stem cells (CFUs) and granulocyte-monocyte progenitors with production of mature granulocytes. Ecotropic-nononcogenic virus is expressed in all cultures and does not adversely effect stem cell replication. We found, however, that cultures established from mice treated in vivo with lymphomagenic AKR viruses (Gross murine leukemia virus and AKR SL3 murine leukemia virus) showed a more rapid decline in CFUs and CFUc than cultures from "normal" AKR mice. Only the former cultures were found to produce lymphomagenic viruses. Furthermore, it was shown that addition of lymphomagenic virus to three-week marrow cultures established from AKR and SJL mice also caused a prompt decline in progenitor cell production and granulopoiesis when compared to medium-treated control cultures. The fate of all cultures was a loss of CFUc and granulocytes with a continuous production of macrophages. The change to macrophage production occurred earlier in the cultures treated with lymphomagenic virus or in those derived from lymphomagenic virus-treated animals. A study of these bone marrow-drived macrophage cultures, as well as cultures of similar morphology but of thymic origin, showed that they could be maintained as continuous lines. Cells from three of the cultures from lymphomagenic virus-treated animals plroduced locally growing sarcoma when inoculated into mice. The macrophages from the declined marrow cultures differed in certain properties from those of the established lines.

AKR murine leukemia virus↗
PubMedDate not supplied

Operant acuity of toddlers and developmentally delayed children with low vision.

The present report describes an operant procedure for the assessment of grating acuity in young and/or developmentally delayed children. Prior to testing, the child was trained to point to a grating presented on one of two equally bright screens. A reward was given to the child for each correct response. During the test, the gratings became progressively finer until the child no longer made consistently correct choices. Normative data from 90 children show improvement in grating acuity during years one to five (from 20/50 to 20/17). Results were also obtained from 100 consecutive pediatric patients who were thought to be visually unresponsive or visually impaired by the referring ophthalmologist. Overall, 12% of these children tested within the normal range, 53% had grating acuities better than 20/200 but below normal, 27% had acuities below 20/200, and 8% were not measurable. These results suggest that a wide range of visual potential exists in this population and that some of these children may benefit from visual aids and training.

Adolescent↗
PubMedDate not supplied

Breast-feeding and optimal visual development.

The goal of the present study was to determine whether dietary supply of omega-3 essential fatty acid (EFA) influences visual development in healthy pre-term and full-term infants. Visual status was examined in human milk-fed infants (ample dietary omega-3 EFA supply) and corn oil-based formula-fed infants (no dietary omega-3 EFA; standard formula prior to 1987). At 57 weeks postconception (4 months adjusted age), both pre-term and full-term human milk-fed infants had significantly better visual evoked potential (VEP) and forced-choice preferential-looking (FPL) acuity than formula-fed infants. Acuity was correlated with a dietary omega-3 sufficiency index from red blood cell membranes obtained at 57 weeks postconception. At 36 months, full-term human milk-fed children had significantly better random dot stereo acuity and letter matching ability than formula-fed children. Stereo acuity and performance on the letter matching test were correlated with a dietary omega-3 sufficiency index from red blood cell membranes obtained at 4 months. These results suggest that dietary omega-3 fatty acids play an important role in visual development.

Breast Feeding↗