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Biomedical subjects

T L Thomas

Publications and source records attributed to T L Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1992

Hormonal and Environmental Regulation of the Carrot lea-Class Gene Dc3.

Dc3 is a carrot lea-class gene belonging to a small gene family that encodes Dc3 and Dc3-like RNA sequences. We have examined the responsiveness to water deficit and abscisic acid (ABA) of the promoter/enhancer complex of Dc3 fused to a beta-glucuronidase (GUS) reporter gene in vegetative cells of transgenic tobacco. In 56-d tobacco, GUS expression in leaves increased about 200-fold during a 3-d drying cycle, during which there were small decreases (3 atmospheres or less) in leaf water potential and a 16-fold increase in free ABA. These effects were reversed by rewatering. Changes in GUS activity were closely paralleled by changes in GUS transcript levels during the desiccation/watering cycle, indicating transcriptional regulation of GUS gene expression. The Dc3 promoter responds to exogenous ABA; the effect is time and concentration dependent, with greater than 10-fold induction in 8 h with 10 mum ABA. Histochemical visualization of GUS activity in seedlings induced by water deficit or exogenous ABA revealed Dc3-driven GUS expression in all organs of transgenic tobacco seedlings. We suggest that the Dc3/GUS reporter system is a sensitive analytical tool to study various environmental effects on plant growth and development.

Journal Article↗
PubMed1992

Cemented versus uncemented femoral components in the ring hip prosthesis.

A prospective, randomised and independently assessed trial of the Ring UPM total hip replacement showed that the quality of the early result was better if the femoral prosthesis was cemented than if it was not. More patients with cemented prostheses were painfree at four months (58% cemented:42% uncemented) and at one year (63% cemented:50% uncemented), but at two years pain relief was equal in both groups. At two years significantly more patients with cemented prostheses could walk without support (96% cemented:62% uncemented, p = 0.01 to 0.05). There is a need for more similar trials to compare the results of contemporary designs of cemented and uncemented total hip prostheses.

Activities of Daily Living↗
PubMed1991

Mortality among women Vietnam veterans, 1973-1987.

A retrospective cohort mortality study was conducted to examine health effects of US military service in Vietnam on women veterans who served there between July 4, 1965 and March 28, 1973. About 4,600 women Vietnam veterans and 5,300 women veterans who had never served in Vietnam were identified from military records and followed for vital status on December 31, 1987. Mortality rates for all causes of death combined and for all cancers among Vietnam veterans were similar to those among non-Vietnam veterans (relative risk (RR) = 0.93). There was a slight excess of mortality from external causes among women Vietnam veterans compared with non-Vietnam veterans (RR = 1.33), primarily due to an excess of motor vehicle accidents (RR = 3.19). Suicide rates were nearly the same in both cohorts (RR = 0.96). Vietnam veterans had twofold increases in mortality from cancers of the pancreas and uterine corpus compared with non-Vietnam veterans. Women Vietnam veterans and non-Vietnam veterans had lower-than-expected mortality from all causes of death combined (standardized mortality ratio (SMR) = 0.82 and 0.88, respectively), based on rates for US women, due to significant deficits of deaths from circulatory diseases. Compared with rates for US women, mortality from cancers of the pancreas (five deaths, SMR = 3.27) and uterine corpus (four deaths, SMR = 4.05) was significantly elevated among Vietnam veteran nurses.

Adult↗
PubMed1991

Reassortants with equine 1 (H7N7) influenza virus hemagglutinin in an avian influenza virus genetic background are pathogenic in chickens.

Reassortants possessing the hemagglutinin (HA) gene from A/Equine/London/1416/73 (H7N7) [Eq/Lond] and five or more genes from A/Chicken/Pennsylvania/1370/83 (H5N2) [Ck/Penn] were lethal in chickens. This result demonstrates that horses can maintain influenza viruses whose HAs are capable of promoting virulence. Thus, reassortment of equine and avian influenza virus genes could generate viruses that might be lethal in domestic poultry.

Amino Acid Sequence↗
PubMed1991

Posttraumatic stress disorder among Vietnam veterans on the Agent Orange Registry. A case-control analysis.

Some of the readjustment problems of Vietnam veterans have been attributed to posttraumatic stress disorder (PTSD). This case-control study compared demographic and military characteristics of 374 Vietnam veterans who had PTSD with 373 healthy Vietnam veterans. Veterans were chosen from the Agent Orange Registry, a Department of Veterans Affairs computerized database of approximately 200,000 Vietnam veterans who volunteered for a physical examination. Case patients and control subjects were frequently-matched by age, year of Registry examination, and race. Crude odds ratios (OR) were used to evaluate the risk of PTSD associated with certain characteristics of Vietnam service, as there was no apparent confounding by other military factors. Being wounded in Vietnam (OR, 2.33; 95% confidence interval (CI), 1.49-3.65) and having a combat job in Vietnam (OR, 1.54; 95% CI, 1.15-2.06) were the only risk factors for PTSD. Those who had noncombat jobs but were wounded had the highest risk of PTSD (OR, 3.56; 95% CI, 1.26-10.06).

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1991

Bipolar hemiarthroplasty for subcapital fracture of the femoral neck. A prospective randomised trial of cemented Thompson and uncemented Moore stems.

We performed a randomised prospective trial to compare the results of 27 cemented and 26 uncemented bipolar hemiarthroplasties in active patients with displaced subcapital fractures of the femoral neck. After a mean follow-up of 17 months, significantly more of the uncemented group were experiencing pain in the hip and using more walking aids than the patients in the cemented group. The incidence of postoperative complications, the early mortality rate and the operating time and blood loss were not significantly different. Using otherwise identical prostheses the early results were much better with a cemented Thompson stem than with an uncemented Austin Moore stem.

Aged↗
PubMed1991

Mortality among Vietnam veterans: with methodological considerations.

The Department of Veterans Affairs previously conducted a proportionate mortality study of Army and Marine Vietnam-era veterans who died during 1965 through 1982. In the present study, 11,325 veterans who died during 1982 through 1984 and 50,743 veterans from the previous analysis made up the final sample of 62,068 veterans. When compared with all non-Vietnam veterans, Army Vietnam veterans had statistically significant excesses of deaths from external causes (proportionate mortality ratio [PMR] = 1.03), laryngeal cancer (PMR = 1.53), and lung cancer (PMR = 1.08). Marine Vietnam veterans had a significantly elevated PMR for external causes (PMR = 1.06) with a significant excess of homicide deaths (PMR = 1.16) when compared to all non-Vietnam veterans. The elevated PMRs for lung cancer and non-Hodgkin's lymphoma among Marine Vietnam veterans reported in the earlier VA study persisted when compared with Marine non-Vietnam veterans. However, it was found that these elevations probably were due to a deficit among the Marine non-Vietnam veterans rather than an excess among Marine Vietnam veterans.

Accidents, Traffic↗
PubMed1990

Mortality and morbidity among Army Chemical Corps Vietnam veterans: a preliminary report.

Nearly 1,000 men serving in Army Chemical Corps units in Vietnam between 1965 and 1971 were responsible for the mixing and application of herbicides, riot control substances, and burning agents. Information on Vietnam service was obtained from military records of 94% of this cohort. Follow-up for vital status on December 31, 1987, was conducted using Department of Veterans Affairs (VA), military, National Death Index, U.S. Internal Revenue Service, and Social Security Administration records. Cause-specific observed numbers of deaths among the 894 men included in the study group were compared with the numbers expected based on rates for U.S. men, adjusting for race, age, and calendar period. Fifty-three deaths from all causes were observed during the study period, compared to 48.8 expected (SMR = 1.09). There were statistically significant excesses of digestive disease deaths (SMR = 2.98), primarily due to cirrhosis, and from motor vehicle accidents (SMR = 2.00). Two deaths were observed from leukemia (0.5 expected) and two from brain cancer (0.4 expected). A total of 257 of the study subjects had received VA inpatient care or Agent Orange registry medical examinations during the study period. Two of these subjects had confirmed diagnoses of Hodgkin's disease (expected = 0.7) and one of hairy cell leukemia. Because of the small study group size and the lack of specificity of information regarding their exposures, these results cannot be attributed to any single chemical agent.

Cause of Death↗
PubMed1990

Molecular analysis of a phylogenetically conserved carrot gene: developmental and environmental regulation.

Extensive studies of gene expression programs in carrot somatic embryos identified a gene, designated Dc3, that serves as a reliable molecular marker for the acquisition of embryogenic potential by carrot cells in culture. The complete sequence of a carrot genomic region, DcG3, encoding a Dc3-like mRNA, was determined. The DcG3 transcription unit contains a single intron and encodes mRNA that is expressed at high levels in embryonic tissue but is undetectable in somatic tissue of carrot. The predicted protein sequence of DcG3 is 163 amino acids and includes two approximately 50 amino acid direct repeats which in turn include additional repetitive elements with an unusual distribution of charged amino acids. Dc3 and Dc3-like mRNAs are encoded by a small divergent gene family. Furthermore, similarities of the Dc3 gene family with genes from other plant species that are expressed in response to environmental and developmental cues suggest a possible role in seed desiccation and possibly in more general water-stress responses in plants. Analysis of transgenic tobacco containing a beta-glucuronidase (GUS) reporter gene fused to a 1.7 kb 5' upstream element of DcG3 defined a promoter/enhancer complex that confers developmentally and environmentally regulated expression of GUS activity. Thus, DcG3 is phylogenetically conserved together with the trans-acting factors required for its regulated expression in transgenic tobacco.

Amino Acid Sequence↗
PubMed1990

Developmentally regulated expression of a sunflower 11S seed protein gene in transgenic tobacco.

Helianthinin is the major 11S seed storage protein of sunflower (Helianthus annuus). Like most seed proteins, helianthinin is encoded by a small gene family; two members of this gene family, HaG3-A and HaG3-D, have been isolated and characterized. Tobacco was transformed with a 6 kb fragment of HaG3-A containing the helianthinin coding region flanked by 3.8 kb upstream and 0.4 kb downstream sequence. Expression of helianthinin was developmentally regulated in seeds of transgenic tobacco plants; furthermore, helianthinin polypeptides were proteolytically processed and targeted to the protein bodies of transgenic tobacco. A fragment of HaG3-A from -2376 to +24 was fused to the beta-glucuronidase (GUS) reporter gene and transferred to tobacco. GUS expression driven by this helianthinin upstream region was developmentally regulated in seeds. Germinating seedlings of the same transformant exhibited a time-dependent decrease in GUS activity with none detected by 6 days post imbibition (DPI). Histochemical analysis of GUS activity in embryos and 2 to 5 DPI seedlings showed expression restricted to the cotyledons and upper embryonic axis with none detected at the radicle end. No GUS activity was found in cotyledons, hypocotyls, leaves, and roots of 18 day seedlings or in leaves of an 8 week F1 plant. These results indicate that the cis-regulatory elements required for developmental control of the HaG3-A helianthinin gene are located in a 2.4 kb upstream region of this gene. This region was sequenced together with the upstream region of the HaG3-D helianthinin gene.

2S Albumins, Plant↗
PubMed1990

Lung cancer mortality among pottery workers in the United States.

A proportionate mortality study suggested that members of the International Brotherhood of Potters and Allied Workers in the United States had an elevated frequency of deaths from non-malignant respiratory disease (PMR = 1.54) and lung cancer (PMR = 1.21). The lung cancer excess occurred exclusively among pottery workers employed in the manufacture of plumbing fixtures (PMR = 1.80). A subsequent cohort study examined mortality among 2055 white men employed in three ceramic plumbing fixture factories. There was a significant excess of non-malignant respiratory disease (SMR = 1.73). Lung cancer mortality was also higher than expected (SMR = 1.43) and was highest among workers whose jobs involved simultaneous exposure to silica and non-fibrous talc (SMR = 2.54). Lung cancer mortality risk increased with increasing number of years of exposure to non-fibrous talc and showed no pattern by number of years of exposure to silica. Among men exposed to talc, lung cancer risk increased with years since first non-fibrous talc exposure and decreased with age at first exposure. The data suggested an association between exposure to non-fibrous talc and excess lung cancer risk; however, the role of silica as a co-factor or promoting agent could not be ruled out.

Adult↗
PubMed1989

Expression of DNA binding proteins in carrot somatic embryos that specifically interact with a cis regulatory element of the French bean phaseolin gene.

Nuclear proteins from bean (Phaseolus vulgarus) embryos bind specifically to a 55 bp DNA sequence located upstream of the seed storage protein gene phaseolin. This sequence is capable of elevating gene expression in transgenic tobacco plants by as much as 150-fold when fused to a chimeric beta-glucuronidase reporter gene. Results presented in this paper demonstrate that nuclear extracts from carrot embryos bind to a phaseolin DNA sequence that includes a phaseolin activator sequence. This specific DNA binding activity is modulated during somatic embryogenesis. Two separable protein species react specifically with the labeled phaseolin DNA fragment (58.0 and 51.7 kDa). These results suggest that the cis- and trans-acting elements controlling gene expression have been highly conserved during evolution.

DNA↗
PubMed1989

Hook-pin fixation of subcapital fractures of the femur: an atraumatic procedure?

Eighty-seven patients with subcapital fractures of the femur treated by hook-pin fixation were reviewed clinically and radiologically with an average follow-up time of 29 months. There were 58 undisplaced and 29 displaced fractures. Seven per cent of the undisplaced and 31 per cent of the displaced fractures developed avascular necrosis (AVN) and failure of fixation was seen in 3.5 per cent and 10 per cent respectively. Overall, 23 per cent of patients developed healing complications of which just over one-half had revision arthroplasty. The AVN rate in the undisplaced group was relatively low, though there was no clear advantage over simple screw fixation. In contrast, the incidence of AVN in displaced fractures was higher than with other methods. Fixation failure was related to surgical error in most instances.

Adult↗
PubMed1989

Flavones. 2. Synthesis and structure-activity relationship of flavodilol and its analogues, a novel class of antihypertensive agents with catecholamine depleting properties.

(3-Phenyl-7-flavonoxy)propanolamines have been shown to exhibit antihypertensive activity in spontaneously hypertensive rats. Although they are structurally similar to classical beta-adrenergic blocking compounds, their activity is not due to inhibition of beta-adrenoceptors. In the present study, a series of simple flavonoxypropanolamines was prepared to further explore the structural requirements for the antihypertensive effect of these compounds. A structure-activity relationship of these derivatives indicates that the position of the oxypropanolamine side chain, the hydroxy group of the side chain, steric bulkiness and length of N substituents, degree of the N-substitution, phenyl group at the 2-position of the chromone nucleus, and substituents of the phenyl group or B ring of the flavone play significant roles in imparting pharmacological effects. In addition, there is a good correlation between the antihypertensive activity and depletion of myocardial norepinephrine. Of these analogues tested, the most effective one was flavodilol. Only the 8-substituted analogue 6 was found to be a beta-antagonist. Flavodilol was chosen for in-depth pharmacological, toxicological, and clinical evaluation.

Adrenal Glands↗
PubMed1989

A sunflower helianthinin gene upstream sequence ensemble contains an enhancer and sites of nuclear protein interaction.

Genes encoding helianthinin, the major seed protein in sunflower, are highly regulated. We have identified putative cis-acting and trans-acting elements that may function in the control of helianthinin expression. A 404-base pair DNA fragment on the sunflower helianthinin gene HaG3D, located 322 base pairs from the transcriptional start site, enhanced beta-glucuronidase expression in transgenic tobacco embryos. Sequences within this fragment were found to bind nuclear proteins present in both sunflower embryo and hypocotyl nuclear extracts. The binding site was localized by phenanthroline-copper ion footprinting experiments to A/T-rich sequences located from -705 to -654. Binding competition experiments revealed that these sunflower proteins also bind to upstream promoter sequences from another helianthinin gene (HaG3A) and two other plant embryo-specific genes, carrot DcG3 and French bean phaseolin. However, sequences of the cauliflower mosaic virus 35S promoter/enhancer complex failed to compete for its binding. Phenanthroline-copper ion footprinting experiments showed that the binding sites for the sunflower proteins in HaG3A (-1463 to -1514 and -702 to -653) and in phaseolin (-671 to -627) are also very A/T-rich, have similar sizes, and are located at similar distances from their respective promoters.

2S Albumins, Plant↗
PubMed1988

Organization of the sunflower 11S storage protein gene family.

We have isolated and characterized genes encoding the sunflower 11S globulin seed storage proteins, collectively termed helianthinin. One gene, designated HaG3, has a primary transcription unit of about 1750 nucleotides including two short intervening sequences. The predicted precursor polypeptide from HaG3 is 493 amino acids long, is rich in glutamine and other nitrogen-rich amino acids and includes the amino acid sequence NGVEETICS. This sequence is highly conserved among 11S seed storage proteins and is involved in the proteolytic processing of these polypeptides. Additional helianthinin sequences are conserved among other seed storage protein genes. Analysis of various cDNA and genomic sequences indicates helianthinins are encoded by a small gene family that includes a minimum of two divergent subfamilies.

2S Albumins, Plant↗