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Biomedical subjects

S E Hall

Publications and source records attributed to S E Hall.

At least 37 records · Page 2Linked to original sources
PubMed1999

Biosynthetic origin of conjugated double bonds: production of fatty acid components of high-value drying oils in transgenic soybean embryos.

Vegetable oils that contain fatty acids with conjugated double bonds, such as tung oil, are valuable drying agents in paints, varnishes, and inks. Although several reaction mechanisms have been proposed, little is known of the biosynthetic origin of conjugated double bonds in plant fatty acids. An expressed sequence tag (EST) approach was undertaken to characterize the enzymatic basis for the formation of the conjugated double bonds of alpha-eleostearic (18:3Delta(9cis, 11trans,13trans)) and alpha-parinaric (18:4Delta(9cis,11trans, 13trans,15cis)) acids. Approximately 3,000 ESTs were generated from cDNA libraries prepared from developing seeds of Momordica charantia and Impatiens balsamina, tissues that accumulate large amounts of alpha-eleostearic and alpha-parinaric acids, respectively. From ESTs of both species, a class of cDNAs encoding a diverged form of the Delta(12)-oleic acid desaturase was identified. Expression of full-length cDNAs for the Momordica (MomoFadX) and Impatiens (ImpFadX) enzymes in somatic soybean embryos resulted in the accumulation of alpha-eleostearic and alpha-parinaric acids, neither of which is present in untransformed soybean embryos. alpha-Eleostearic and alpha-parinaric acids together accounted for as much as 17% (wt/wt) of the total fatty acids of embryos expressing MomoFadX. These results demonstrate the ability to produce fatty acid components of high-value drying oils in transgenic plants. These findings also demonstrate a previously uncharacterized activity for Delta(12)-oleic acid desaturase-type enzymes that we have termed "conjugase."

Amino Acid Sequence↗
PubMed1999

Genetic control and dynamics of the cellular immune response to the human T-cell leukaemia virus, HTLV-I.

About 1% of people infected with the human T-cell leukaemia virus, type 1 (HTLV-I) develop a disabling chronic inflammatory disease of the central nervous system known as HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Patients with HAM/TSP have a vigorous immune response to HTLV-I, and it has been widely suggested that this immune response, particularly the HTLV-I-specific cytotoxic T-lymphocyte (CTL) response, causes the tissue damage that is seen in HAM/TSP. In this paper we summarize recent evidence that a strong CTL response to HTLV-I does in fact protect against HAM/TSP by reducing the proviral load of HTLV-I. We conclude that HTLV-I is persistently replicating at a high level, despite the relative constancy of its genome sequence. These results imply that antiretroviral drugs could reduce the risk of HAM/TSP by reducing the viral load, and that an effective anti-HTLV-I vaccine should elicit a strong CTL response to the virus. The dynamic nature of the infection also has implications for the epidemiology and the evolution of HTLV-I.

Human T-lymphotropic virus 1↗
PubMed1999

HLA alleles determine human T-lymphotropic virus-I (HTLV-I) proviral load and the risk of HTLV-I-associated myelopathy.

The risk of disease associated with persistent virus infections such as HIV-I, hepatitis B and C, and human T-lymphotropic virus-I (HTLV-I) is strongly determined by the virus load. However, it is not known whether a persistent class I HLA-restricted antiviral cytotoxic T lymphocyte (CTL) response reduces viral load and is therefore beneficial or causes tissue damage and contributes to disease pathogenesis. HTLV-I-associated myelopathy (HAM/TSP) patients have a high virus load compared with asymptomatic HTLV-I carriers. We hypothesized that HLA alleles control HTLV-I provirus load and thus influence susceptibility to HAM/TSP. Here we show that, after infection with HTLV-I, the class I allele HLA-A*02 halves the odds of HAM/TSP (P < 0.0001), preventing 28% of potential cases of HAM/TSP. Furthermore, HLA-A*02(+) healthy HTLV-I carriers have a proviral load one-third that (P = 0.014) of HLA-A*02(-) HTLV-I carriers. An association of HLA-DRB1*0101 with disease susceptibility also was identified, which doubled the odds of HAM/TSP in the absence of the protective effect of HLA-A*02. These data have implications for other persistent virus infections in which virus load is associated with prognosis and imply that an efficient antiviral CTL response can reduce virus load and so prevent disease in persistent virus infections.

Alleles↗
PubMed1999

A case-control study of quality of life and functional impairment in women with long-standing vertebral osteoporotic fracture.

There have been several studies of the impact of vertebral osteoporotic fracture on the quality of life and functionality of individual subjects. To date, however, no direct comparisons with age-matched normal subjects without vertebral fracture have been made. The radiographs of 145 female clinic patients with vertebral fractures were reviewed by the study physicians. The controls were recruited from the electoral role and by media appeal. One hundred and sixty-seven women had radiographs taken to determine those without vertebral fracture. Fracture subjects and controls had to be ambulant and were excluded if they had significant radiologic evidence of degenerative disk or joint disease of the spine. One hundred cases and one hundred controls were matched by 5-year age groups. The number, position and severity of the vertebral fracture on the lateral radiographs of the cases was recorded. Quality of life was measured using the Short Form-36 (SF-36) (maximum score 100) and a utility score calculated from these results (maximum score 1). Two measurements of functionality were employed: the Modified Barthel Index (MBI) to assess the activities of daily living (maximum score 100) and the Timed 'Up & Go' (TUG) that measured the time taken for the subject to rise from sitting in a chair, walk 3 m along a line, return to the chair and sit down. The fracture subjects had 2.9 +/- 1.6 (mean +/- SD) vertebral fractures and the time since last fracture was 5.1 +/- 4.8 years. The SF-36 physical function component summary index results were: fracture subjects 36 +/- 11, controls 48 +/- 9 (p < 0.001). The SF-36 mental health component summary index results were: fracture subjects 50 +/- 11, controls 54 +/- 8 (p < 0.05). The utility scores were: fracture subjects 0.64 +/- 0.08, controls 0.72 +/- 0.07 (p < 0.001). The MBI results were: fracture subjects 97 +/- 5, controls 99 +/- 1 (p < 0.01). The TUG results were: fracture subjects 13.8 +/- 7.3 s, controls 10.1 +/- 4.1 s (p < 0.01). TUG and MBI scores correlated well with SF-36 scores; however, no domain of the SF-36 or functional measure correlated with either the number of vertebral fractures or the time since last vertebral fracture. Thus, clinically reported vertebral fractures impair both the quality of life and functionality of these subjects. The adverse impact of vertebral fracture on quality of life and functionality needs to be recognized by medical practitioners, subjects and the community, so that adequate health resources can be devoted to the prevention and treatment of this debilitating condition condition.

Aged↗
PubMed1999

Effect of lamivudine on human T-cell leukemia virus type 1 (HTLV-1) DNA copy number, T-cell phenotype, and anti-tax cytotoxic T-cell frequency in patients with HTLV-1-associated myelopathy.

Patients with human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) typically have a high HTLV-1 proviral load in peripheral blood mononuclear cells and abundant, activated HTLV-1-specific cytotoxic T lymphocytes (CTLs). No effective treatment for HAM/TSP has been described so far. We report a 10-fold reduction in viral DNA for five patients with HAM/TSP during treatment with the reverse transcriptase inhibitor lamivudine. In one patient with recent-onset HAM/TSP, the reduction in viral DNA was associated with a fall in the frequency of CTLs specific to two peptides in the immunodominant viral antigen Tax. The half-life of peripheral blood mononuclear cell populations was estimated from changes in viral DNA copy number, CTL frequency, reduction in CD25 expression, and the loss of dicentric chromosomes following radiation-induced damage. Each of these four different techniques indicated a cellular half-life of approximately 3 days consistent with continuous lymphocyte replication and destruction. These results indicate that viral replication through reverse transcription significantly contributes to the maintenance of HTLV-1 viral DNA load. The relative contribution of proliferation versus replication may vary between infected people.

Adult↗
PubMed1999

Lung type II cell and macrophage annexin I release: differential effects of two glucocorticoids.

Annexin I (lipocortin 1) is abundant in lung secretions. Concentrations rise after oral glucocorticoid, but the effect of inhaled budesonide on annexin I release is unknown. Extracellular annexin I in bronchoalveolar lavage fluid (BALF) from 11 asthmatic patients was unaffected by inhaled budesonide (800 microgramgs twice daily for 4 wk; mean after budesonide, 110 ng/mg albumin; after placebo, 107 ng/mg albumin). Rat alveolar macrophages (AMs) and alveolar epithelial type II (ATII) cells were cultured alone and with budesonide or dexamethasone. Mean basal concentrations of cellular (3.5 ng/10(6) AMs; 4.4 ng/10(6) ATII cells) and secreted (1. 4 ng/10(6) AMs; 1.8 ng/10(6) ATII cells) annexin I were similar in AMs and ATII cells. Although budesonide subdued annexin I secretion from both cell types, dexamethasone stimulated annexin I release. Annexin I release from ATII cells peaked at 10(-7) M dexamethasone but at 10(-3) M dexamethasone from AMs. Thus, at low concentrations of dexamethasone, ATII cells probably contribute more annexin I to respiratory tract secretions than AMs, although at high concentrations, both cells probably contribute. The study demonstrates previously undescribed differences between glucocorticoids and between AMs and ATII cells with respect to annexin I regulation.

Administration, Inhalation↗
PubMed1999

Periodontitis and cytokine expression in CD14 deficient patients.

Patients with paroxysmal nocturnal haemoglobinuria (PNH) are deficient in monocytic CD14. The aim of this research was to determine the interrelationships among periodontal disease status, local levels, and monocytic secretion of inflammatory mediators in patients with PNH and matched controls. This study utilised a cross sectional, non-randomised design. PNH patients and matched controls (age, race, gender) were assessed for periodontal status, levels of PGE2 and IL-1beta within the gingival crevicular fluid (GCF), and levels released from lipopolysaccharide (LPS) stimulated peripheral blood monocytes in culture. Results indicate no statistical differences in extent and severity of periodontal disease or GCF mediator levels between the two groups. Monocyte responses to LPS demonstrated significant differences in PGE2 (P = 0.0009) and IL-1beta (P = 0.003) secretion with PNH monocytes secreting significantly less than controls. A significant positive association was found between the monocytic and GCF levels of PGE2 for all subjects (P = 0.003), PNH (P = 0.015), and control (P = 0.049) groups. This study demonstrated that GPI anchor deficient monocytes have reduced expression of inflammatory mediators in vitro.

Adult↗
PubMed1998

Sequence and expression analysis of WT1 and Sox9 in the red-eared slider turtle, Trachemys scripta.

Temperature-dependent sex-determination (TSD) is a phenomenon that has been characterized at the ecological, morphological, and endocrinological levels in some reptilian species. We have begun to investigate TSD at the level of molecular development by cloning, sequencing, and analyzing the expression of two genes, WT1 and Sox9, in the red-eared slider turtle Trachemys scripta. We obtained almost full-length cDNA clones for WT1 and Sox9 that were greater than 73% identical to the human homologues at the nucleotide level. WT1 was expressed in urogenital tissue at all developmental stages examined (Yntema stages 12-20) at incubation temperatures that produce males (26 degrees C) or females (32 degrees C). Sox9 was also expressed throughout these same stages, but some differences were observed. At both 26 degrees C and 32 degrees C Sox9 was expressed in the mesonephroi and the undifferentiated gonads until Yntema stage 20, when only the gonad from the 26 degrees C embryos expressed a high level. In addition, there were two transcripts of Sox9 at all stages, but the relative proportion of the two transcripts differed at the two temperatures. Although the similarities in gene expression between a TSD species and other species with genotypically determined sex probably reflect the common features of organogenesis, differences may illustrate unique mechanisms for TSD.

Amino Acid Sequence↗
PubMed1998

Expression of a new RNA-splice isoform of WT1 in developing kidney-gonadal complexes of the turtle, Trachemys scripta.

WT1 is a tumor suppressor gene encoding a zinc finger DNA-binding protein required for normal vertebrate kidney and gonad development. Although the sequence and function of this gene has been studied mostly in mammals, comparative analysis in other vertebrates may suggest regions of conservation of function as well as evolution of function. We have initiated a study of this gene in the freshwater turtle, Trachemys scripta, a species that demonstrates temperature dependent sex determination. The turtle WT1 amino acid sequence (GenBank Accession No. AF019779) is over 85% identical to that of other species overall, but there are some major differences. The greatest differences are in the N-terminal portion of the peptide which is thought to mediate transcriptional repression by interaction with other proteins. Turtle WT1, like those of the alligator, chicken, and Xenopus lacks the proline- and glycine-rich stretches that are present in mammalian WT1. Exon 5, which is alternatively spliced in mammals, is altogether absent in the non-mammalian vertebrates. In addition, turtle WT1 is alternatively spliced so that exon 4 is either present or absent. These differences suggest that the interaction of reptilian WT1 with other factor required for mediation of activity may be different than the interaction of mammalian WT1. It also suggests that alternative splicing is a conserved regulatory mechanism of vertebrate WT1. Expression of WT1 in turtle embryonic kidney-gonadal complexes begins after the mesonephroi have formed and continues at least until the bipotential gonad begins to differentiate. Although the proportions of the different splice isoforms are relatively constant during these stages of kidney development, the level of steady state expression is increased in embryos incubated at 26 degrees C, the testis-producing temperature.

Alternative Splicing↗
PubMed1998

The use of stable carbon isotope analysis to detect the abuse of testosterone in cattle.

The use of stable carbon isotope analysis to detect the administration of anabolic steroids to cattle was investigated. Samples were extracted by solid-phase extraction on C18 cartridges. Stable isotope ratios (13C:12C) were measured by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) of the underivatised extracts. A programmed temperature vaporiser (PTV) injector was installed in the GC-IRMS system, which conferred a number of advantages. First, it allowed large volumes of sample to be injected whilst the injector liner was cool. The solvent was subsequently vented to the atmosphere prior to transfer of the sample to the GC column. Thus a significantly greater amount of sample could be presented for analysis, thereby increasing the sensitivity. Second, by this means virtually all the solvent could be removed prior to analysis. This eliminates solvent peak tailing, which can be a major problem in GC-IRMS. Finally, the PTV allowed the use of higher initial GC oven temperatures, which in turn facilitated the analysis of underivatised steroids by reducing the GC run time and improving the chromatographic peak shape. The carbon isotope composition of 5 beta-androstane-3 alpha,17 alpha-diol, the major metabolite of testosterone found in bovine bile, was measured in bile samples from untreated cattle and from cattle injected intramuscularly with testosterone or a mixture of testosterone esters. There was considerable inter-animal variation in the values obtained and there was no significant difference between samples from treated and untreated animals. However, when the isotopic composition of the metabolite was normalised with respect to that of an endogenous reference compound (cholesterol) in the same sample, the difference between treated and untreated animals become statistically significant.

Anabolic Agents↗
PubMed1998

"Central" auditory gap detection: a spatial case.

Normal listeners were tested for their temporal auditory gap detection thresholds using free-field presentation of white-noise stimuli delivered from the left (L) and right (R) poles of the interaural axis. The noise bursts serving as the leading and trailing markers for the silent period were presented in either the same (LL,RR) or different (LR,RL) auditory locations. The duration of the leading marker was a second independent variable. Gap thresholds for stimuli in which the markers had the same location were low, and usually were independent of the duration of the leading marker. Gap thresholds for the LR and RL conditions were longer. These gap thresholds were sensitive to the duration of the leading marker, and increased as the leading marker duration decreased. This finding is consistent with the hypothesis that a relative timing operation mediates gap detection when the markers activate different perceptual channels. The present data suggest that this timing process can operate on perceptual channels emerging from central nervous system processing.

Adult↗
PubMed1997

Synthesis and protein kinase C inhibitory activities of balanol analogs with replacement of the perhydroazepine moiety.

Balanol is a potent protein kinase C (PKC) inhibitor that is structurally composed of a benzophenone diacid, a 4-hydroxybenzamide, and a perhydroazepine ring. A number of balanol analogs in which the perhydroazepine moiety is replaced have been synthesized and their biological activities evaluated against both PKC and cAMP-dependent kinase (PKA). The results suggested that the activity and the isozyme/kinase selectivity of these compounds are largely related to the conformation about this nonaromatic structural element of the molecules.

Azepines↗
PubMed1997

Detection of silent intervals between noises activating different perceptual channels: some properties of "central" auditory gap detection.

This article describes four experiments on gap detection by normal listeners, with the general goal being to examine the consequences of using noises in different perceptual channels to delimit a silent temporal gap to be detected. In experiment 1, subjects were presented with pairs of narrow-band noise sequences. The leading element in each pair had a center frequency of 2 kHz and the trailing element's center frequency was parametrically varied. Gap detection thresholds became increasingly poor, sometimes by up to an order of magnitude, as the spectral disparity was increased between the noise bursts that marked the gap. These data suggested that gap-detection performance is impoverished when the underlying perceptual timing operation requires a comparison of activity in different perceptual channels rather than a discontinuity detection within a given channel. In experiment 2, we assessed the effect of leading-element duration in within-channel and between-channel gap detection tasks. Gap detection thresholds rose when the duration of the leading element was less than about 30 ms, but only in the between-channel case. In experiment 3, the gap-detection stimulus was redesigned so that we could probe the perceptual mechanisms that might be involved in stop consonant discrimination. The leading element was a wideband noise burst, and the trailing element was a 300-ms bandpassed noise centered on 1.0 kHz. The independent variable was the duration of the leading element, and the dependent variable was the smallest detectable gap between the elements. When the leading element was short in duration (5-10 ms), gap thresholds were close to 30 ms, which is close to the voice onset time that parses some voiced from unvoiced stop consonants. In experiment 4, the generality of the leading-element duration effect in between-channel gap detection was examined. Spectrally identical noises defining the leading and trailing edges of the gap were presented to the same or to different ears. There was a leading-element duration effect only for the between channel case. The mean gap threshold was again close to 30 ms for short leading-element durations. Taken together, the data suggest that gap detection requiring a temporal correlation of activity in different perceptual channels is a fundamentally different task to the discontinuity detection used to execute gap detection performance in the traditional, within-channel paradigm.

Adult↗
PubMed1996

Synthesis and protein kinase C inhibitory activities of acyclic balanol analogs that are highly selective for protein kinase C over protein kinase A.

A series of balanol analogs in which the perhydroazepine ring and the p-hydroxybenzamide moiety were combined into an acyclic linked unit have been prepared and evaluated for their inhibitory properties against the serine/threonine kinase PKC. Several low-micromolar to low-nanomolar inhibitors of the alpha, beta I, beta II, gamma, delta, epsilon and eta PKC isozymes were prepared. In general, these acyclic balanol analogs were found to be highly selective for PKC over the serine/threonine kinase PKA. The type and number of atoms linking the benzophenone ester to the p-hydroxyphenyl group necessary for optimal PKC inhibition were investigated. The most potent compounds contained a three-carbon linker in which the carboxamide moiety of balanol had been replaced by a methylene group. The effect of placing substituents on the three-carbon chain was also investigated. The preferred compounds contained either a 2-benzenesulfonamido (6b) or a 1-methyl (21b) substituent. The preferred compounds 6b and 21b were tested against a panel of serine/threonine kinases and found to be highly selective for PKC. The more active enantiomer of 6b, (S)-12b, was 3-10-fold more active than the R-enantiomer against the PKC isozymes. The effect of making the analogs more rigid by making the three-carbon chain part of a five-membered ring, but with retention of the methylene replacement for the carboxamide moiety, led to potent PKC inhibitors including anti-substituted pyrrolidine analog 35b and the most potent PKC inhibitor in the series, anti-substituted cyclopentane analog 29b. The anti cyclopentane analog 29b, was a low-micromolar inhibitor of the PMA-induced superoxide burst in neutrophils, and its carboxylic ester was a high-nanomolar inhibitor of neutrophils. Finally esterification of 21b, (S)-12b, and 35b turned these potent PKC inhibitors into low-micromolar inhibitors of neutrophils.

Animals↗
PubMed1996

(S)-13-[(dimethylamino)methyl]-10,11,14,15-tetrahydro-4,9:16, 21-dimetheno-1H, 13H-dibenzo[e,k]pyrrolo[3,4-h][1,4,13]oxadiazacyclohexadecene-1,3(2H)-d ione (LY333531) and related analogues: isozyme selective inhibitors of protein kinase C beta.

Protein kinase C (PKC) is a family of closely related serine and threonine kinases. Overactivation of some PKC isozymes has been postulated to occur in several diseases states, including diabetic complications. Selective inhibition of overactivated PKC isozymes may offer a unique therapeutic approach to disease states such as diabetic retinopathy. A novel series of 14-membered macrocycles containing a N-N'-bridged bisindolylmaleimide moiety is described. A panel of eight cloned human PKC isozymes (alpha, beta I, beta II, gamma, delta, epsilon, sigma, eta) was used to identify the series and optimize the structure and associated activity relationship. The dimethylamine analogue LY333531 (1), (S)-13-[(dimethylamino)methyl]-10,11,14,15-tetrahydro-4,9:16, 21-dimetheno-1H, 13H-dibenzo[e,k]pyrrolo[3,4-h][1,4,13]oxadiazacyclohexadecene++ +-1,3(2H)-dione, inhibits the PKC beta I (IC50 = 4.7 nM) and PKC beta II (IC50 = 5.9 nM) isozymes and was 76- and 61-fold selective for inhibition of PKC beta I and PKC beta II in comparison to PKC alpha, respectively. The additional analogues described in the series are also selective inhibitors of PKC beta. LY333531 (1) exhibits ATP dependent competitive inhibition of PKC beta I and is selective for PKC in comparison to other ATP dependent kinases (protein kinase A, calcium calmodulin, caesin kinase, src tyrosine kinase). The cellular activity of the series was assessed using bovine retinal capillary endothelial cells. Retinal endothelial cell dysfunction has been implicated in the development of diabetic retinopathy. Plasminogen activator activity stimulated by a phorbol ester (4 beta-phorbol 12,13-dibutyrate) in endothelial cells was inhibited by the compounds in the series with ED50 values ranging from 7.5 to 0.21 microM. A comparison of the PKC isozyme and related ATP dependent kinase inhibition profiles is provided for the series and compared to the profile for staurosporine, a nonselective PKC inhibitor. The cellular activity of the series is compared with that of the kinase inhibitor staurosporine.

Amino Acid Sequence↗