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Biomedical subjects

H Burger

Publications and source records attributed to H Burger.

At least 91 records · Page 5Linked to original sources
PubMed1997

Maternal serum vitamin A levels are not associated with mother-to-child transmission of HIV-1 in the United States.

HIV-1 transmission from mother to child has been associated with maternal vitamin A status in studies of women living in Africa. This finding has raised the question of whether vitamin A supplementation might help reduce transmission in the United States as well as worldwide. In industrialized nations, however, both the vitamin A nutritional status of HIV-1-infected pregnant women and the association of vitamin A levels with vertical transmission were unknown. Furthermore, vitamin A is teratogenic, and supplements during pregnancy have caused birth defects. To investigate whether maternal serum levels of vitamin A (retinol) and three other micronutrients correlate with vertical transmission of HIV-1 in the United State, we studied 95 HIV-1-infected pregnant women and followed their infants to determine whether transmission occurred. Sera were obtained during the third trimester of pregnancy from 95 HIV-1-infected women living in the New York and Los Angeles metropolitan areas. The two cohorts were established to study vertical transmission of HIV-1 and to reflect the racial, ethnic, and socioeconomic status of HIV-1-infected in women in the United States. We measured serum levels of vitamin A (retinol) and three other micronutrients, vitamin E (alpha-tocopherol), beta-carotene, and lycopene, in the mothers using reverse-phase high-performance liquid chromatography and determined the HIV-1 infection status of their infants using virus cultivation and polymerase chain reaction. Sixteen of the 95 women transmitted HIV-1 to their infants. Statistical analysis of the data indicated that low maternal serum retinol levels during the third trimester of pregnancy were not associated with mother-to-child transmission of HIV-1. None of the women had retinol levels so low as to have clinical symptoms of vitamin A deficiency. The serum levels of alpha-tocopherol, beta-carotene, and lycopene, three micronutrients that act as antioxidants and enhance immune function, were also measured. Statistical analysis of the data revealed no association of the levels of these three micronutrients with vertical transmission of HIV-1. Analysis of the data obtained from 95 women in the United States indicates that vitamin A deficiency is rare, and serum retinol levels are not associated with risk of vertical HIV-1 transmission. In view of the teratogenic effects of vitamin A when taken as a supplement during pregnancy, pregnant HIV-1-infected women living in nations where vitamin A deficiency is not a public health problem should not be advised to take extra vitamin A supplements.

Carotenoids↗
PubMed1997

Bax upregulation is an early event in cisplatin-induced apoptosis in human testicular germ-cell tumor cell line NT2, as quantitated by flow cytometry.

Expression of the apoptosis-associated proteins Bcl-2 and Bax was quantitated by flow cytometry (FCM) in chemosensitive testicular germ-cell tumor NT2 cells, and the results were compared with those obtained by Western blotting. NT2 cells were incubated with cisplatin (3.1 microM for 2 h at 37 degrees C), and 24, 48, and 72 h later were analyzed for induction of apoptosis, and for modulation of the expression of cell death suppressing protein Bcl-2, as well as cell death promoting protein Bax. Apoptosis was quantitated by binding of annexin V conjugated with fluorescein isothiocyanate (FITC) to the cell membrane. Cisplatin-treatment induced apoptosis in NT2 cells. The apoptotic cell population increased in time, and at t = 72 h after drug incubation, about 90% of cells that were present in the cell culture were apoptotic. Subsequently, we determined the expression of the Bcl-2 and Bax proteins by FCM and Western blotting before and after drug treatment. NT2 cells had low constitutive expression levels of Bcl-2 and elevated constitutive expression levels of Bax protein, as determined by both methods. At t = 24 h and 48 h after drug treatment, no changes were observed in the expression of the Bcl-2 protein, as quantitated by FCM and Western blotting. Also, the expression of the Bax protein had not changed, based on Western blotting. However, FCM revealed that in a specific subpopulation of drug-treated NT2 cells, Bax expression was increased. On the basis of forward and perpendicular light-scatter this subpopulation, which consisted of large, early apoptotic, swollen cells with increased internal complexity, was sorted, and showed abundant Bax protein by FCM and Western blotting. Our results demonstrate that the chemosensitivity of NT2 cells is probably due to a low intrinsic threshold for drug-induced apoptosis that is accompanied by overexpression of the death-promoting Bax protein during the early stages of the apoptotic process. We conclude that FCM is superior to Western blotting for the detection of heterogeneous expression of Bax in a given cell population.

Apoptosis↗
PubMed1997

High Resolution Study of the 3nu2, nu1 + nu2, and nu2 + nu3 Bands of H2Te

High-resolution Fourier transform spectra of a natural sample of hydrogen telluride and of monoisotopic H2130Te have been recorded in the 3.2-4-0 μm spectral region where the 3nu2, nu1 + nu2, and nu2 + nu3 bands of this molecule absorb. The (030) rotational levels were least-squares fitted using a Watson-type Hamiltonian whereas it proved necessary to consider the strong Coriolis interaction coupling the (110) and the (011) rotational levels. In this way all the experimental levels were calculated to within their experimental uncertainty and precise sets of vibrational energies and rotational and coupling constants were obtained for the (030), (110), and (011) vibrational states of H2130Te, H2128Te, H2126Te, H2125Te, H2124Te, H2123Te, and H2122Te. The band centers for the most abundant isotopic species, namely H2130Te, are:nuo(3nu2) = 2565.4428, nuo(nu1 + nu2) = 2911.4098, nuo(nu2 + nu3) = 2915.9599 cm-1 Copyright 1997Academic Press

Journal Article↗
PubMed1997

Simultaneous Analysis of the 2nu2, nu1, and nu3 Bands of Hydrogen Telluride

Spectra of a natural sample of hydrogen telluride as well as a spectrum of monoisotopic H2 130Te have been recorded by means of Fourier transform spectrometry with a resolution of 0.003 cm-1 in the spectral domain 7.5-4.3 μm where it is easy to observe the main absorbing bands nu1 and nu3. We have located and assigned for the first time the 2nu2 band which appears in the lower wavenumber range of the recorded spectral domain near 1700 cm-1. It proved necessary to treat simultaneously the three states (020), (100), and (001). nu1 and nu3 are indeed Coriolis-coupled vibration-rotation bands and it was observed that a few rotational levels of (001) could not be fitted to within their experimental accuracy without considering the second-order Coriolis interaction between the rotational levels of (020) and (001). In this way all the experimental levels were calculated to within the experimental uncertainty, and precise sets of vibrational energies and rotational and coupling constants were obtained for the seven most abundant H2Te isotopic species, namely H2 130Te, H2 128Te, H2 126Te, H2 125Te, H2 124Te, H2 123Te, and H2 122Te. For the most abundant isotopic species H2 130Te the bands centers arenu0 (2nu2) = 1715.9568, nu0 (nu1) = 2065.2709, nu0 (nu3) = 2072.1101 cm-1. Copyright 1997Academic Press

Journal Article↗
PubMed1997

High Resolution Study of the nu2 , 2nu1 , nu1 + nu3 , and 2nu3 Bands of Hydrogen Telluride: Determination of Equilibrium Rotational Constants and Structure

High resolution Fourier transform spectra of a natural and a 130 Te monoisotopic sample of H2 Te have been recorded at a resolution of 0.0022 cm-1 in the 11.6 μm spectral region, as well as a spectrum of a natural sample of H2 Te at a resolution of 0.0051 cm-1 in the 2.4 μm region. In the 11.6 μm region the main absorbing band is the nu2 band, the analysis of which was rather easy. On the other hand, in the 2.4 μm region three bands are absorbing, namely 2nu1 , nu1 + nu3 , and 2nu3 , the last being much weaker than the others. The analysis in this spectral domain was much more difficult because of resonances. Indeed it proved not possible to reproduce the observed lines without taking into account the Darling-Dennison interaction between the levels of the (200) and (002) states and the Coriolis interactions between the levels of (200) and (101) and between those of (101) and (002). Considering these interactions allowed us to calculate very satisfactorily all the experimental levels, and precise sets of vibrational energies and rotational and coupling constants were obtained for the seven most abundant H2 Te isotopic species, namely H2 130 Te, H2 128 Te, H2 126 Te, H2 125 Te, H2 124 Te, H2 123 Te, and H2 122 Te. For the most abundant species, H2 130 Te, the band centers in cm-1 are nu0 (nu2 ) = 860.6563, nu0 (2nu1 ) = 4062.8842, nu0 (nu1 + nu3 ) = 4063.3697, and nu0 (2nu3 ) = 4137.0454. These results, combined with those obtained for other vibrational states, have been used to derive the equilibrium rotational constants and their corrections. Finally, by neglecting the electronic corrections, the equilibrium structure of H2 130 Te was obtained as follows: r e (Te-H) = 1.65145(10) A, alphae (HTeH) = 90.2635(90)degrees.

Journal Article↗
PubMed1997

Study of the v3 = 1 State of 80SeF6 by Fourier Transform Spectroscopy

The Fourier transform infrared spectrum of monoisotopic 80SeF6 has been recorded in the 760-792 cm-1 region with an effective resolution of ca. 2.3 x 10(-3) cm-1. The 80SeF6 sample was prepared by burning monoisotopic 80Se powder (99.2%) in an excess of fluorine. The analysis of infrared transitions of the nu3 band enabled the determination of parameters of the Hamiltonian developed up to the third order and the fourth order. The standard deviation obtained is equal to 4 x 10(-4) cm-1 for the third-order development and 3.2 x 10(-4) cm-1 for the fourth-order development. In the two analyses, 2900 lines were assigned and fitted. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Can Isotopic Substitution Change a Bright State into a Dark State? The Case of the v3 = 1 State of FClO3

High-resolution infrared spectra of monoisotopic samples of F35Cl18O3 and F37Cl18O3 have been recorded with the purpose of analyzing the nu3 fundamental at 535 cm-1. However, this band could not be observed whereas it had been seen and studied earlier in F35Cl16O3. To determine the parameters of the v3 = 1 state, indirect methods were used. Hot bands nun + nu3 - nu3 (n = 1 or 2) were first analyzed and their LSCD (Lower State Combination Differences) yielded rotational parameters of nu3. Then, with the help of nu1 + nu3, all rovibrational parameters of nu3 were obtained. Similar methods were applied to spectra of F35Cl16O3 and F37Cl16O3 to prove that the parameters of nu3 obtained in this fashion are identical to those determined directly for these isotopomers and are even more comprehensive. It is shown that the different character of nu3 in the two 18O and in the two 16O isotopomers is due to the fact that the former are much closer to a spherical top molecule ((A0 - B0)/A0 = 0.015). This is not only reflected in intensities different by two orders of magnitude but also in the very different values of alpha3B in these two pairs. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

High-Resolution Infrared Spectrum of D3Si79Br in the nu1/nu4 Region: The Structure of Silyl Bromide

FTIR spectra of monoisotopic D3Si79Br covering the bands nu1 (a1, 1580.637 cm-1) and nu4 (e, 1615.085 cm-1) have been recorded with a resolution of 3 x 10(-3) cm-1. The rovibrational analysis revealed severe perturbations of the -5 </= KDeltaK </= 4 series of nu4 while nu1 and the high-K subbands of nu4 are almost unperturbed and served to determine the parameters of the v1 = 1 and v4 = 1 states, with sigma(Fit) ca. 5 x 10(-4) cm-1. Equilibrium rotational constants of H3Si79Br and D3Si79Br were deduced with the help of the vibrational corrections alphai. The r0, rs, rmrho, and re structures of silyl bromide have been determined. The experimental values of the HSiH angle and of the Si-H distance are found in excellent agreement with their ab initio predictions. The re structure is re(Si-H) = 1.470(2) A, re(Si-Br) = 2.207(1) A, and alphae(HSiH) = 110.5(2)degrees. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

Longitudinal changes in ultrasound parameters of the calcaneus.

We examined with a median follow-up of 1.4 years (range 1.0-2.0 years) the rates of change per year in ultrasound parameters of the calcaneus. Speed of sound (SOS), Broadband ultrasound attenuation (BUA) and Stiffness were measured twice in 543 subjects (224 men) participating in the Rotterdam Study. SOS fell by -2.5 m/s per year in both sexes (95% CI -4.0 to -1.1 m/s per year in men and -3.6 to -1.4 m/s per year in women). Stiffness decreased by -0.62 (-1.33 to 0.09) per year in men and -0.66 (-1.24 to -0.08) per year in women. In men the rate of change in SOS and Stiffness tended to increase with age. BUA did not change significantly during follow-up in either sex. The prospectively assessed rates of loss differed considerably from those observed cross-sectionally, especially for SOS in men (cross-sectional -0.7 m/s per year, longitudinal -2.5 m/s per year). There was substantial variation between individuals both in changes per year in SOS and in changes per year in BUA. With a median follow-up time of 1.4 years, approximately 27% of the variation in the rate of change for SOS could be explained by measurement error while for BUA this was approximately 9% and for Stiffness 11%. Only a small percentage of subjects had changes larger than could be accounted for by measurement error (SOS: men 26.8%, women 21.6%; BUA: men 28.5%, women: 38.8%; Stiffness: men 32.6%, women 35.1%). The latter may limit the use of ultrasound measurements as a follow-up tool in individuals rather than in populations.

Age Factors↗
PubMed1997

Sexuality, hormones and the menopausal transition.

OBJECTIVES: To assess the validity and reliability of a sexuality questionnaire, and to assess the relationship of sexual functioning to age, menopausal status and hormone levels. METHODS: Cross-sectional analysis of a population-based cohort of 201 women aged 48-58 years in the fourth year of a longitudinal study. Sexual functioning was measured by self-completed questionnaire. E2, FSH. Inhibin, total T and SHBG were sampled on cycle days 4-8 or after 3 months of amenorrhoea. RESULTS: Internal consistency, as measured by Cronbach's alpha, was 0.71. Six factors were found on principal components factor analysis: (1) Feelings for Partner, (2) Sexual Responsivity, (3) Sexual Frequency, (4) Libido, (5) Partner Problems and (6) Vaginal Dryness/Dyspareunia. Sexual Responsivity decreased with age (beta = -0.060, P = 0.05), and Vaginal Dryness/Dyspareunia decreased with log E2 (beta = -0.181. P < 0.001). Testosterone was not associated with the aspects of female sexual functioning measured in this study. CONCLUSIONS: This longitudinal study found that most aspects of female sexual functioning were not affected by age, menopausal functioning or hormone levels.

Age Factors↗
PubMed1997

Biology of HIV-1 in women and men.

The 1990s have been marked by tremendous progress in understanding HIV-1 infection and disease progression in infected individuals. The new discoveries have direct applications in predicting clinical outcomes and monitoring antiviral therapies. With the identification of secondary receptors for HIV-1 cell entry, the CCR-5 receptor was found to be a single genetically determined factor influencing both HIV-1 transmission and disease progression. Quantitation of HIV-1 RNA led to the discoveries that detectable or even high levels of HIV-1 replication occur during all phases of infection, and that plasma HIV-1 RNA levels are powerful predictors of clinical outcome. These findings have increased the ability to predict disease progression and to monitor-antiviral therapy in infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1997

CCR5 genotypes in sexually active couples discordant for human immunodeficiency virus type 1 infection status.

Persons who are homozygous for the delta32 polymorphism of the CCR5 chemokine receptor gene are highly protected against human immunodeficiency virus type 1 (HIV-1) infection. Previous studies described 54 HIV-1-discordant couples in whom no virus transmission occurred despite extensive sexual contact. The possible role of the delta32 polymorphism in the lack of HIV-1 transmission between these partners was studied. No participants were homozygous for the delta32 allele, but the proportion that was heterozygous was higher among HIV-1-seronegative than HIV-1-seropositive partners (28% vs. 11%, P = .05). This association was seen in heterosexual couples (P = .03) but not in homosexual couples (P = .74). Among white persons, who are most likely to carry the delta32 allele, 38.9% of HIV-1-uninfected and 5.6% of HIV-1-infected heterosexual partners were heterozygous (P = .04). These data are consistent with a possible association between the heterozygous delta32 genotype in heterosexual sex partners and partial protection against HIV-1 infection, and they emphasize the importance of analyzing different risk groups in studies of host factors that influence infection.

Alleles↗
PubMed1997

Cumulative pregnancy rates in couples with anovulatory infertility compared with unexplained infertility in an ovulation induction programme.

Using a retrospective analysis, we compared cumulative pregnancy rates, early pregnancy failure rates and multiple pregnancy rates in couples with polycystic ovarian syndrome (PCOS) (n = 148), hypogonadotrophic or eugonadotrophic hypogonadism (n = 91) and unexplained infertility (n = 117), who were treated in an ovulation induction clinic between January 1991 and December 1995. The women were treated with either human menopausal gonadotrophin (HMG) or purified follicle stimulating hormone (FSH). The cumulative pregnancy rate (derived from life-table analysis) after four ovulatory treatment cycles was 70% in the PCOS group, 74% in the hypogonadism group and 38% in the unexplained infertility group. The cumulative pregnancy rate in the unexplained infertility group was significantly lower than the other groups (P < 0.001) but there was no significant difference between PCOS and hypogonadism using the log rank test. The early pregnancy failure rate was 25% in the PCOS group, 27% in the hypogonadism group and 26% in the unexplained infertility group (chi(2) = 0.132, not significant). The multiple pregnancy rate was 20% in the PCOS group, 30% in the hypogonadism group and 17% in the unexplained infertility group (chi(2) = 2.105, not significant). Treatment of anovulatory infertility using HMG or FSH is effective irrespective of the cause. Couples with unexplained infertility are less successfully treated using HMG: correction of unexplained infertility may involve more than simple correction of possible subtle ovulatory defects.

Adult↗
PubMed1997

Vertebral deformities and functional impairment in men and women.

The objective of this study was to assess the prevalence and health effects of vertebral deformities in men and women. The study was carried out as part of the cross-sectional baseline phase of The Rotterdam Study, a prospective population-based cohort study of residents aged 55 years or over of a district of Rotterdam, The Netherlands. The prevalence of vertebral deformities according to a modification of the Eastell method and concomitant functional impairment were assessed in a random sample of 750 men and 750 women. The prevalence of moderate (grade I) vertebral deformities was 8 and 7% in men and women, respectively. For severe deformities (grade II), these percentages were 4 and 8%. In men, the prevalence of both moderate and severe deformities increased with age. In women, however, the prevalence of moderate vertebral deformities remained constant, opposite to a marked increase in severe deformities. Moderate vertebral deformity was significantly associated with impaired rising in men only. Severe vertebral deformity was associated with a significantly increased risk of general disability and the use of a walking aid in both men and women, impaired bending in men, and impaired rising in women. It is concluded that (1) vertebral deformities are only slightly less common in men than in women from the general population and (2) severe progression with age occurs in women only and (3) severe vertebral deformity is, particularly in men, related to functional impairment.

Aged↗
PubMed1997

Well-being and the menopausal transition.

This paper examines the relationship between well-being, age, menopausal status, hormone levels and hot flashes. Data from the first 4 years of longitudinal observation from the Melbourne Women's Midlife Health project was utilized. This study involved a population-based sample of 405 women interviewed annually. Blood was taken during the follicular phase (if still menstruating) for estradiol, sex hormone binding globulin, follicle stimulating hormone and testosterone. A validated well-being scale was used. Positive affect increased with age while negative affect decreased with age but only in the postmenopausal category. Positive affect was significantly lower in the 2 years postmenopausal group but this effect of menopausal status did not remain when hot flashes were included in the analysis. Negative affect was highest in the 1-2 years postmenopausal group. Although hot flashes adversely affected negative moods, a significant effect of menopausal status remained. No direct association between any of the hormone levels and positive or negative affect scores was evident. In conclusion, this study found that well-being was decreased in the first 2 years after the first menstrual period but began to improve spontaneously after this time.

Adaptation, Psychological↗
PubMed1997

The life style of young persons after lower limb amputation caused by injury.

In order to determine whether lower limb amputation changes the social life and free time activities of persons who were at the time of amputation young, a questionnaire was sent to 519 persons after trans-tibial or higher level of lower limb amputation who were at the time of amputation younger than 51 years, amputated because of injury, permanently resident in Slovenia and had visited the outpatient prosthetics clinic of the Rehabilitation Institute of Slovenia at least once in the last five years (1989-94). There 228 responses, which were statistically analysed. It was found that after amputation most persons participated less frequently in social activities, especially persons who were older at the time of amputation and also those who are older today. Changes in participation in social activities were not influenced by level of education. Free time activities changed after amputation. Some 93 persons completely changed their free time activities and only 30 were still interested in the same activities as before. The three most frequent free time activities before amputation were cycling, team ball games and farm work. After amputation they were reading, watching television and/or listening to radio and music and housekeeping. It is concluded that lower limb amputation severely changes the social life and free time activities of persons who were young at the time of amputation.

Adaptation, Psychological↗
PubMed1997

Mobility of persons after traumatic lower limb amputation.

The objective of this study was to determine the influence of time span since amputation on mobility of persons experiencing traumatic lower limb amputation. A special questionnaire was sent to such persons and responses were analysed statistically. The subjects comprised 223 persons after traumatic lower limb amputation, residents of Slovenia. We discovered that 186 (74.2%) are using their prosthesis for more than 7 hours per day, 109 (52.2%) are able to walk outdoors without crutches, and 129 (57.8%) climb more than 20 stairs per day. In addition, those who are walking without crutches, walking longer distances, still cycling and driving a care are, on average, 5-10 years younger than the others. However, around one-third of persons who were young at the time of amputation face limitations of mobility later in life. A total of 76 (35.3%) are able to walk only up to 500 m out of doors, 38 (18.2%) can walk only with a pair of crutches, 62 (29.7%) need a cane or one crutch, and 37 (16.6%) cannot climb stairs. We conclude that successful fitting and usage of a prosthesis by persons after lower limb amputation promotes independent walking and mobility in everyday life. The level of independence achieved is related to time span since amputation.

Activities of Daily Living↗