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Biomedical subjects

T L Thomas

Publications and source records attributed to T L Thomas.

At least 19 recordsLinked to original sources
PubMed1998

Failure of adjunctive bicarbonate to improve outcome in severe pediatric diabetic ketoacidosis.

STUDY OBJECTIVE: Although adjunctive intravenous bicarbonate therapy is commonly recommended for children with severe diabetic ketoacidosis (DKA), no studies assessing clinical outcome with this therapy have ever been performed. Our objective was to determine whether bicarbonate therapy influenced outcome for pediatric DKA. METHODS: The study was a retrospective consecutive case series of 147 admissions for severe DKA (initial pH < or = 7.15 and glucose concentration > or = 300 mg/dL [16.7 mmol/L]) in 106 children during a 16-year period at a tertiary university medical center. Descriptive statistics were applied to the 147 admissions. The first patient admitted with DKA was then selected for each of the 106 children, and clinical and laboratory data were compared between subjects who did and did not receive bicarbonate. Multivariate and matched pair analyses were performed to control potentially confounding variables. RESULTS: Fifty-seven of the 147 patients admitted with DKA (39%) were successfully treated without bicarbonate, including 9 with a pH of 7.00 or less and one with a pH of 6.73. The frequency of complications was comparable between bicarbonate and nonbicarbonate groups (4% versus 2%, P = 1.00). The mean duration of hospitalization for children receiving bicarbonate was 23% (16 hours) longer than children who did not receive bicarbonate in the multivariate analysis (P = .07) and 37% (22 hours) longer in the matched pair analysis (P = .01). The mean rate of metabolic recovery by three distinct measures was similar between groups, and the sample had 80% power to detect differences of 14% to 29% in these measures. CONCLUSION: We found no evidence that adjunctive bicarbonate improved clinical outcome in children with severe DKA. The rate of metabolic recovery and complications were similar in patients treated with and without bicarbonate, and prolonged hospitalizations were noted in the bicarbonate group. We conclude that adjunctive bicarbonate is unnecessary and potentially disadvantageous in severe pediatric DKA.

Adjuvants, Pharmaceutic↗
PubMed1998

PEI1, an embryo-specific zinc finger protein gene required for heart-stage embryo formation in Arabidopsis.

We used virtual subtraction, a new gene isolation strategy, to isolate several genes of interest that are expressed in Arabidopsis embryos. These genes have demonstrated biological properties or have the potential to be involved in important biological processes. One gene isolated by virtual subtraction is PEI. It encodes a protein containing a Cys3His zinc finger domain associated with a number of animal and fungal transcription factors. In situ hybridization results showed that PEI1 is expressed throughout the embryo from globular to late cotyledon stage. Transgenic Arabidopsis plants expressing a PEI1 antisense gene produced white seeds in which embryo development did not progress through heart stage. Aberrant embryos failed to form cotyledons, but the embryonic root appeared to be normal. Aberrant embryos did not turn green, and the expression of genes involved in photomorphogenesis was drastically attenuated. In culture, aberrant embryos did not form true leaves, but root formation was apparently normal. These results suggest that PEI1 is an embryo-specific transcription factor that plays an important role during Arabidopsis embryogenesis, functioning primarily in the apical domain of the embryo.

Amino Acid Sequence↗
PubMed1997

Isolation of a novel class of bZIP transcription factors that interact with ABA-responsive and embryo-specification elements in the Dc3 promoter using a modified yeast one-hybrid system.

Dc3 is a carrot lea class gene that is abundantly expressed during somatic and zygotic embryogenesis. Its expression is normally embryo-specific and also can be induced by abscisic acid. The regulatory elements mediating the embryo-specific expression of Dc3 reside within the proximal promoter region (-117 to +26), which is also essential for ABA-induced expression. In this study, an optimized version of the yeast one-hybrid system has been used to clone factors that bind to the promoter region of the Dc3 gene. Twenty-five million yeast transformants were screened in a single experiment, and nine independent cDNA clones were isolated from a sunflower library that encode proteins that specifically bind to functional cis-regulatory elements in the Dc3 promoter. Analysis of these clones showed that they are derived from three different mRNA species that encode two basic leucine zipper proteins. The basic regions of these proteins, named DPBF-1 and 2 (Dc3 Promoter-Binding Factor-1 and 2), respectively, are nearly identical to each other and are similar to the plant G-box binding factor GBF-4. Outside the basic region, however, DPBF-1 and 2 diverge significantly from each other and from other known factors. Both factors have transcriptional activity in yeast, and bind to DNA as dimers. Unlike other plant bZIP factors, DPBF-1 and 2 recognize sequences containing the ACACNNG core. Cloning of these factors demonstrates the power of the one-hybrid approach when optimally applied.

Abscisic Acid↗
PubMed1996

Differential regulation of small heat-shock genes in plants: analysis of a water-stress-inducible and developmentally activated sunflower promoter.

We have isolated two sunflower genes, Ha hsp18.6 G2 and Ha hsp17.7 G4, that encode small heat shock proteins (sHSPs). RNAse A protection experiments, carried out with RNA probes transcribed from each gene and hybridized to sunflower total RNA, allowed us to distinguish their mRNA accumulation patterns. In sunflower, Ha hsp17.7 G4 mRNAs accumulated during zygotic embryogenesis at 25 degrees C. In vegetative tissues, these mRNAs accumulated in response to either heat shock (42 degrees C), abscisic acid (ABA), or mild water stress treatments. In all cases, the mRNAs were transcribed from the same initiation site. In contrast, Ha hsp 18.6 G2 mRNAs accumulated only in response to heat-shock. This result demonstrates differential regulation of these two sHSP genes. The complex regulation depicted by the Ha hsp 17.7 G4 promoter has been further analyzed in transgenic tobacco, using G4::GUS translational fusions. Developmental induction of Ha hsp 17.7 G4 during zygotic embryogenesis was faithfully reproduced in the transgenic plants. 5'-distal sequences (between -1132 and -395) were required to confer a preferential spatial expression of GUS activity in the cotyledons. More proximal sequences (from -83 to +163) conferred to the chimeric genes most of the developmental regulation, and the responses to ABA and heat shock characteristic of the Ha hsp17.7 G4 promoter. The water stress response of this gene was not reproduced in transgenic tobacco and, thus, could be uncoupled from its regulation during embryogenesis.

Abscisic Acid↗
PubMed1996

Comparative gene expression in sexual and apomictic ovaries of Pennisetum ciliare (L.) Link.

Limited emphasis has been given to the molecular study of apomixis, an asexual method of reproduction where seeds are produced without fertilization. Most buffelgrass (Pennisetum ciliare (L.) Link syn = Cenchrus ciliaris L.) genotypes reproduce by obligate apomixis (apospory); however, rare sexual plants have been recovered. A modified differential display procedure was used to compare gene expression in unpollinated ovaries containing ovules with either sexual or apomictic female gametophytes. The modification incorporated end-labeled poly(A)+ anchored primers as the only isotopic source, and was a reliable and consistent approach for detecting differentially displayed transcripts. Using 20 different decamers and two anchor primers, 2268 cDNA fragments between 200 and 600 bp were displayed. From these, eight reproducible differentially displayed cDNAs were identified and cloned. Based on northern analysis, one cDNA was detected in only the sexual ovaries, two cDNAs in only apomictic ovaries and one cDNA was present in both types of ovaries. Three fragments could not be detected and one fragment was detected in ovaries, stems, and leaves. Comparison of gene expression during sexual and apomictic development in buffelgrass represents a new model system and a strategy for investigating female reproductive development in the angiosperms.

Cloning, Molecular↗
PubMed1996

Catalase is encoded by a multigene family in Arabidopsis thaliana (L.) Heynh.

The catalase multigene family in Arabidopsis includes three genes encoding individual subunits that associate to form at least six isozymes that are readily resolved by nondenaturing gel electrophoresis. CAT1 and CAT3 map to chromosome 1, and CAT2 maps to chromosome 4. The nucleotide sequences of the three coding regions are 70 to 72% identical. The amino acid sequences of the three catalase subunits are 75 to 84% identical and 87 to 94% similar, considering conservative substitutions. Both the individual isozymes and the individual subunit mRNAs show distinct patterns of spatial (organ-specific) expression. Six isozymes are detected in flowers and leaves and two are seen in roots. Similarly, mRNA abundance of the three genes varies among organs. All three mRNAs are highly expressed in bolts, and CAT2 and CAT3 are highly expressed in leaves.

Amino Acid Sequence↗
PubMed1996

Identification of novel mRNAs in immature seeds of Arabidopsis thaliana.

Although most of the major discernible morphogenetic events in plants occur after germination, the overall architectural pattern of the mature plant is established during early events of embryogenesis. So far, few genes that are expressed specifically during embryogenesis have been identified. This is due primarily to technical difficulties associated with the mass ratios of the embryo and the surrounding maternal tissue and to the lack of molecular and cellular markers to direct screening efforts. We have developed a series of molecular approaches to study the early events of embryogenesis. These include 'virtual subtraction' of a cDNA library with high specific-activity cDNA probes generated from both seed and non-seed tissue, PCR amplification of gene family members from an immature seed cDNA library using primers specific to conserved domains, differential display analysis of mRNA populations and high throughput expressed sequence tag (EST) analysis. These techniques have led to the identification and isolation of several novel seed-specific cDNAs.

Amino Acid Sequence↗
PubMed1995

Complete sequence of the binary vector Bin 19.

Despite the widespread use of Bin 19 as a vector for plant transformation, detailed sequence information on its T-DNA region has only recently become available. We now show that the non-T-DNA region, like the T-DNA region, contains several superfluous insertions and find that some functional elements may not contain optimal sequences. Knowledge of the complete 11,777 bp sequence will aid in the construction of exceptionally efficient derivative vectors of approximately half this size. Precise knowledge of restriction sites and removal of unnecessary sequences will facilitate plasmid manipulations and plant transformation.

Base Sequence↗
PubMed1995

Cancer mortality patterns among women who served in the military: the Vietnam experience.

In response to concerns of women veterans regarding the long-term health effects of military service in Vietnam, the Department of Veterans Affairs has been conducting a retrospective cohort mortality study of women Vietnam veterans. Military records were used to identify approximately 4600 women who served in Vietnam between July 4, 1965, and March 28, 1973, and a comparison cohort of nearly 5300 women who served during the same time frame but not in Southeast Asia or the Pacific theater. Current data include vital status determinations as of December 31, 1991, with a total of 532 deaths and an average follow-up of just over 20 years for both groups. Both the Vietnam and non-Vietnam women cohorts had a significant deficit of deaths from all causes compared to women in the US population. The two cohorts showed no difference in total mortality or in deaths from all cancers. A significant excess risk of pancreatic cancer was observed among Vietnam nurses compared to either non-Vietnam nurses (relative risk = 5.74) or women in the US population (standardized mortality ratio (SMR) = 2.78). Vietnam nurses also had an elevated risk of dying from cancer of the uterine corpus. Non-Vietnam nurses had a higher lung cancer mortality rate than women in the general population (SMR = 1.55) or nurses who served in Vietnam. Observed deficits of deaths from all causes and circulatory system diseases generally confirm a healthy selection bias for entry into and retention in the military that has been observed among men serving in the Armed Forces.

Adult↗
PubMed1994

Occupational exposure to chlorinated aliphatic hydrocarbons and risk of astrocytic brain cancer.

Chlorinated aliphatic hydrocarbons (CAHs) were evaluated as potential risk factors for astrocytic brain tumors. Job-exposure matrices for six individual CAHs and for the general class of organic solvents were applied to data from a case-control study of brain cancer among white men. The matrices indicated whether the CAHs were likely to have been used in each industry and occupation by decade (1920-1980), and provided estimates of probability and intensity of exposure for "exposed" industries and occupations. Cumulative exposure indices were calculated for each subject. Associations of astrocytic brain cancer were observed with likely exposure to carbon tetrachloride, methylene chloride, tetrachloroethylene, and trichloroethylene, but were strongest for methylene chloride. Exposure to chloroform or methyl chloroform showed little indication of an association with brain cancer. Risk of astrocytic brain tumors increased with probability and average intensity of exposure, and with duration of employment in jobs considered exposed to methylene chloride, but not with a cumulative exposure score. These trends could not be explained by exposures to the other solvents.

Astrocytoma↗
PubMed1994

Using mortality rates as a screening tool: the experience of the Department of Veterans Affairs.

BACKGROUND: Despite widespread agreement that outcome analyses should be followed by in-depth review of the care provided by outlier providers, there are few, if any, reports in the literature describing the effectiveness of this approach to quality improvement. In 1991, the Department of Veterans Affairs (VA) completed a study to measure hospital-specific mortality rates for VA facilities and to use these rates as a screening tool for focused medical record reviews. METHODS: The first phase of the project consisted of a comparison of fiscal year 1986 mortality rates for each VA medical center with aggregated VA data, using logistic regression analysis to adjust for patient characteristics related to mortality. In the second phase, medical record reviews of cases from hospitals with elevated levels of mortality were conducted. RESULTS: The mortality rate analysis identified 44 facilities with rates that were significantly elevated overall or within specific patient categories. Both the mortality rate analysis and the medical record review suggested that quality concerns were more common in predominantly psychiatric medical centers than in other facilities. CONCLUSION: The study uncovered important opportunities for improvement, particularly regarding the quality of medical care provided in VA psychiatric hospitals, suggesting there is value in performing intensive review of outlier providers in outcome analyses. However, serious questions remain concerning the validity of the use of administrative data-bases to assess hospitalwide mortality.

Cause of Death↗
PubMed1994

Developmental and hormonal regulation of sunflower helianthinin genes: proximal promoter sequences confer regionalized seed expression.

DNA elements involved in the regulation of two sunflower helianthinin genes were identified by analysis of beta-glucuronidase (GUS) expression in transgenic tobacco driven by sequences derived from the 5' upstream regions of these genes. A 2.4-kb upstream region of the helianthinin gene HaG3-A conferred rigorous developmental GUS expression in transgenic tobacco seeds with no significant GUS activity in nonembryonic tissues. Regions of the helianthinin upstream regulatory ensemble (URE) conferred ectopic expression in nonembryonic tissues when analyzed outside of the context of the complete helianthinin regulatory complex. A proximal promoter region was identified that conferred significant GUS expression in seeds but not in leaves of transgenic tobacco. Three sequence motifs that bind to seed nuclear proteins were identified in the proximal promoter region; mutations in these motifs significantly reduced the level of nuclear protein binding. Another important class of cis-regulatory elements was identified in the helianthinin URE that conferred abscisic acid-responsive GUS expression. In the full-length helianthinin URE, these elements only responded to abscisic acid in the developing seed, suggesting that the helianthinin gene contains additional regulatory elements, possibly in the proximal promoter region, that ensure hierarchical control in the developing seed.

2S Albumins, Plant↗
PubMed1994

Relative contribution of type I and II corticosterone receptors in VMH lesion-induced obesity and hyperinsulinemia.

Ventromedial hypothalamic (VMH) lesion-induced obesity is accompanied by hyperinsulinemia and hyperphagia, which are dependent upon corticosterone (Cort) for their expression. Whether Cort exerts these actions through its stimulation of type I or II Cort receptor populations is unknown. Therefore, food intake and weight gain were measured in obese adrenalectomized VMH-lesioned rats given continuous infusion of various doses of either a type I-receptor agonist (aldosterone), a type II-receptor agonist (RU-28362), or several combination doses. Similarly, the receptor population responsible for lesion-induced hyperinsulinemia was identified. Type II receptor stimulation restored the hyperphagia, weight gain, and hyperinsulinemia of adrenalectomized VMH-lesioned animals, while type I receptor stimulation blocked their weight loss.

Adrenalectomy↗
PubMed1993

Isolation of a delta 6-desaturase gene from the cyanobacterium Synechocystis sp. strain PCC 6803 by gain-of-function expression in Anabaena sp. strain PCC 7120.

The enzyme delta 6-desaturase is responsible for the conversion of linoleic acid (18:2) to gamma-linolenic acid (18:3 gamma). A cyanobacterial gene encoding delta 6-desaturase was cloned by expression of a Synechocystis genomic cosmid library in Anabaena, a cyanobacterium lacking delta 6-desaturase. Expression of the Synechocystis delta 6-desaturase gene in Anabaena resulted in the accumulation of gamma-linolenic acid (GLA) and octadecatetraenoic acid (18:4). The predicted 359 amino acid sequence of the Synechocystis delta 6-desaturase shares limited, but significant, sequence similarity with two other reported desaturases. Analysis of three overlapping cosmids revealed a delta 12-desaturase gene linked to the delta 6-desaturase gene. Expression of Synechocystis delta 6- and delta 12-desaturases in Synechococcus, a cyanobacterium deficient in both desaturases, resulted in the production of linoleic acid and gamma-linolenic acid.

Amino Acid Sequence↗
PubMed1993

Efficacy of equine influenza vaccines for protection against A/Equine/Jilin/89 (H3N8)--a new equine influenza virus.

A new H3N8 equine influenza virus [A/Equine/Jilin/1/89 (Eq/Jilin)] appeared in Northeastern China in 1989 and caused high mortality in horses; the available evidence indicates that it has not yet spread outside this region of the world. Serological analysis with postinfection ferret sera in haemagglutination inhibition (HI) tests confirmed that Eq/Jilin is antigenically distinct from H3N8 equine influenza viruses isolated between 1963 and 1991 and also showed that a current equine influenza virus [A/Equine/Alaska/1/91 (H3N8)] had undergone antigenic drift. In the present study we determine if vaccine against a recent H3N8 influenza virus [A/Equine/Kentucky/1277/90 (Eq/Kentucky)] that was standardized for haemagglutinin content will protect mice against lethal challenge with the new H3N8 influenza virus from China. Complete protection is defined as prevention of virus replication in the lungs of mice 3 days after challenge. High doses of Eq/Kentucky vaccine in aqueous suspension (0.5-5.0 micrograms HA per dose) provided minimal protection against Eq/Jilin challenge as judged by virus titres in the lungs of vaccinated animals. Eq/Kentucky vaccine in adjuvant (1.0-5.0 micrograms HA per dose) did provide complete protection against challenge with Eq/Jilin in mice. Eq/Jilin vaccine in aqueous suspension induced complete protection of mice against challenge with Eq/Kentucky at doses from 0.5 to 5 micrograms HA and in adjuvant doses of Eq/Jilin from 0.1-5.0 micrograms HA were efficacious. Homologous protection against Eq/Jilin or Eq/Kentucky was induced by doses of vaccine from 0.5-5.0 micrograms HA per dose in aqueous suspension and from 0.01-5.0 micrograms HA per dose in adjuvant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1993

The carrot secreted glycoprotein gene EP1 is expressed in the epidermis and has sequence homology to Brassica S-locus glycoproteins.

Non-embryogenic carrot suspension cells secrete the EP1 glycoprotein. A cDNA clone encoding EP1 was isolated and sequenced. The EP1 sequence revealed a region of homology with Brassica S-locus glycoprotein genes, an Arabidopsis S-like gene and putative S-like receptor protein kinases from maize and Arabidopsis. EP1 gene expression, analysed by in situ mRNA localization, was detected in cells located at the surface of the seedling: in the epidermis of the root, the hypocotyl and the cotyledons, in the root cap, and in a crescent of cells in the apical dome of the shoot. In developing seeds, expression was most pronounced in both the inner and outer integument epidermis.

Amino Acid Sequence↗
PubMed1993

Low-energy subtrochanteric fractures in elderly patients: results of fixation with the sliding screw plate.

Forty-two patients with subtrochanteric fractures were treated from 1987 through 1990. Of these, 31 patients above 70 years of age (average, 81.9) had nonpathologic low-energy fractures that were internally fixed with a sliding screw-plate device. Subtrochanteric fractures with an associated intertrochanteric component were the most common type. Interfragmentary compression was used in long oblique and spiral fractures and those with large butterfly fragments. Patients were mobilized early and allowed partial weightbearing for 6-8 weeks. There was a 29% mortality rate within 3 months of injury. Of the remaining cases, followed for a minimum of 6 months (average, 11.8 months), 20 (91%) united satisfactorily. There was loss of fixation in one case and one instance of plate fracture. We found, given the special circumstances in elderly patients, that the device was suitable not only for subtrochanteric fractures with an intertrochanteric element but also for four-part fractures and two-part spiral fractures. The sliding screw-plate permitted passage of interfragmentary screws and facilitated medial displacement and collapse, which are valuable in cases with medial comminution in reducing the bending moment on the plate. These factors may help reduce the incidence of plate failure and, coupled with familiarity with its use, make it a reliable implant for such difficult fractures in elderly patients.

Accidental Falls↗