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Biomedical subjects

M Thomas

Publications and source records attributed to M Thomas.

At least 487 records · Page 27Linked to original sources
PubMed1994

The prevalence of tuberculosis infection among Year 8 schoolchildren in inner Sydney in 1992.

OBJECTIVE: To determine the prevalence of tuberculosis (TB) infection in Year 8 schoolchildren (aged 12-14 years) in Sydney. DESIGN: Cross-sectional survey. SETTING: 22 inner city Sydney secondary schools. PARTICIPANTS: 2290 Year 8 school children enrolled in 1992. OUTCOME MEASURES: Distribution of Mantoux test reaction size and proportion of children who were Mantoux positive (i.e., having Mantoux reaction > or = 15 mm with previous Bacille Calmette-Guérin vaccination; > or = 10 mm without). RESULTS: Of the 2290 children, 1836 (81%) were screened and 1801 Mantoux reactions were read. Ten per cent of children were Mantoux positive--27% of foreign-born children and 2% of Australian-born children (relative risk 16.7, 95% confidence interval 10.6-26.4). Two children were found to have active TB disease. CONCLUSION: There is a high prevalence of primary (non-contagious) TB infection in children aged 12-14 years in inner Sydney, mostly confined to children born overseas. Thus there is a large pool of infected children at risk of developing active (contagious) adult-type TB disease in the future. This public health problem should be addressed by identification and treatment of those infected.

Adolescent↗
PubMed1994

Analysis of a brain-specific isozyme. Expression and chromatin structure of the rat aldolase C gene and transgenes.

Aldolase C mRNA is detected by Northern blot in all fetal tissues in rat; it is very abundant in the adult brain and undetectable in the other adult tissues. However, reverse transcriptase polymerase chain reaction amplification indicates that this gene is not totally repressed in these tissues. A DNase-I hypersensitivity site located in a 115-base pair proximal promoter fragment is detectable in the brain as well as in other adult tissues. Two MspI/HpaII restriction sites located at -3800 and -450 base pairs are demethylated in the brain and totally or partially methylated in other tissues. In transgenic mice, a 12.5-kilobase genomic fragment is strongly and tissue specifically expressed in different lines, with conservation of a methylation pattern similar to that of the endogenous gene. A chloramphenicol acetyltransferase gene directed by either 800 or 115 base pairs of aldolase C 5'-flanking sequences is tissue specifically expressed in transgenic mice, but the level of expression is very low. This level is greatly increased when the transgene consists of a chloramphenicol acetyltransferase hybrid gene directed by 5.5 kilobases of aldolase C 5'-flanking sequences. We propose therefore that the chromatin structure around the aldolase C promoter is accessible in fetal tissues, then remains open in the adult brain, where the gene is very active, as well as in tissues in which it is practically inactive. The specificity of expression in the brain is conferred by a short 115-base pair proximal promoter fragment that needs more upstream sequences to be fully active.

Animals↗
PubMed1994

Transient thiol-expression and thiol disulphide cluster-receptor communications: a molecular basis for blastocyst-uterine interactions during implantation.

The attachment of trophoblast to uterine epithelium during implantation is an intricate and complex instance of cell-cell communication, the molecular aspects of which remain rather undefined. In this study, we screened the surface domains of the pre-, peri- and post implantation mouse embryos with a thiol-specific probe. Transient thiol-expression in peri-implantation embryos suggested their involvement in implantation either through disulphide bridge establishment or through a communication between a thiol-disulphide cluster of the blastocyst and a corresponding receptor of the endometrium.

Animals↗
PubMed1994

Arabidopsis homologs of the shaggy and GSK-3 protein kinases: molecular cloning and functional expression in Escherichia coli.

The conservation in evolution of fundamental signal transduction modules offers a means of isolating genes likely to be involved in plant development. We have amplified by PCR Arabidopsis cDNA and genomic sequences related to the product of the shaggy/zeste-white 3 (sgg) segment polarity gene of Drosophila. This regulatory protein is functionally homologous to glycogen synthase kinase-3 in mammals (GSK-3), which regulates, among others, the DNA-binding activity of the c-jun/AP1 transcription factor. Analysis of PCR products led to the identification of five genes; for two of which, corresponding full-length cDNAs, ASK-alpha and gamma (for Arabidopsis shaggy-related protein kinase), were characterized. The encoded proteins were 70% identical to GSK-3 and sgg over the protein kinase catalytic domain and, after production in Escherichia coli, autophosphorylated mainly on threonine and serine residues, but phosphotyrosine was also detected. ASK-alpha and ASK-gamma also phosphorylated phosphatase inhibitor-2 and myelin basic protein, on threonine and serine, respectively. The high conservation of the protein kinases of GSK-3 family, and their action at the transcriptional level, suggest that the ASK proteins have important functions in higher plants.

Amino Acid Sequence↗
PubMed1994

A prospective study in a southern Indian hospital on the prescription of medication during the lying in period following childbirth.

The awareness of the inherent risks attached to medication use during pregnancy is increasing. There is, however, a paucity of available following childbirth. We have conducted a prospective study in women who gave birth in hospital with the objective of analysing the use of medication in this lying in period. The results show that, in addition to the vitamins and minerals routinely prescribed for every young mother and the antipyretics administered as required, the following medicaments were most often used: analgesics (by approx. 9%), anti-inflammatory agents (49%) and antibiotics (38%). The antibiotics were either used prophylactically or, in cases of proven infection, administered therapeutically. The use of antibiotics appears more intensive compared to western countries, presumably due to the greater risk of infection in this group in India. On the other hand, the use of sleep inducing medication and tranquillizers during the lying in period appears, in comparison to other studies, almost negligible. The majority of the women were unaware of the potential side-effects of medication during breastfeeding.

Adolescent↗
PubMed1994

The prognostic significance of epidermal growth factor receptor expression in breast cancer.

The association between epidermal growth factor receptor (EGFR) expression, clinicopathological variables, silver-stained nuclear organizer region (Ag-NOR) counts, and patient survival was determined in 93 patients with operable breast cancer. The EGFR expression was found to be significantly associated with the presence and number of axillary lymph node metastases (P = 0.0429), but not with age, menopausal status, tumor size, histologic type or grade, or Ag-NOR counts. In a univariate analysis, a significant difference was also observed in the survival of patients stratified by tumor size (P = 0.0091), histologic grade (P = 0.0352), axillary lymph node metastases (P = 0.0001), and EGFR expression (P = 0.0263). However, a multivariate analysis revealed that axillary lymph node metastases was the only strong independent predictor of survival (P < 0.0001). When axillary lymph node metastases were excluded from the Cox model, the EGFR expression tended to be an independent prognostic factor (P = 0.0558). The results of this study thus indicate that the prognostic value of EGFR expression is limited because the EGFR expression is significantly associated with axillary lymph node metastases.

Adult↗
PubMed1994

The relationship of p53 protein and lymph node metastases in invasive breast cancer.

The p53 expression in invasive breast cancers from 106 patients was correlated with clinicopathological variables to ascertain its usefulness for estimating prognosis. The p53 expression was significantly associated with the number of axillary lymph node metastases and the presence of internal mammary lymph node metastases; however, it was not associated with age, menopausal status, histologic type, or tumor size. Although p53 expression was a significant prognostic factor according to univariate analysis, it did not appear to be an independent prognostic factor according to multivariate analysis. Thus, the prognostic power of p53 expression is likely to be weak and therefore probably of limited clinical value. Nevertheless, the number of patients in our study was small, and we believe that an investigation of a larger series of patients is indicated.

Adult↗
PubMed1994

Opportunities for manipulating the seed protein composition of wheat and barley in order to improve quality.

Wheat and barley are the major temperate cereals, being used for food, feed and industrial raw material. However, in all cases the quality may be limited by the amount, composition and properties of the grain storage proteins. We describe how a combination of biochemical and molecular studies has led to an understanding of the molecular basis for breadmaking quality in wheat and feed quality in barley, and also provided genes encoding key proteins that determine quality. The control of expression of these genes has been studied in transgenic tobacco plants and by transient expression in cereal protoplasts, providing the basis for the production of transgenic cereals with improved quality characteristics.

Amino Acid Sequence↗
PubMed1994

Intracellular calcium signalling in peripheral cells of patients with bipolar affective disorder.

Consistent with previous studies, elevated free intracellular calcium ion concentrations ([Ca2+]i) were found in blood platelets and lymphocytes of patients with mania and bipolar depression. Incubation with an ultrafiltrate of plasma from patients with bipolar illness had no effect on intracellular calcium ion concentration in platelets from normal subjects, suggesting that elevated [Ca2+]i is not due to a circulating factor. As was true in an earlier study of the effect of lithium on platelets, incubation with therapeutic levels of carbamazepine lowered [Ca2+]i in lymphocytes from affectively ill patients but not controls. Increased [Ca2+]i in peripheral cells may reflect a diffuse change in cellular homeostasis and may contribute to mixtures as well as rapid alternations of activity of affective, behavioral and physiologic systems in bipolar illness. Correction of the abnormality may at least be a marker of a relevant therapeutic action if it is not the action itself.

Bipolar Disorder↗
PubMed1994

[Solitary subcutaneous metastasis of a chondrosarcoma].

We report on a rare case of a solitary subcutaneous metastasis from a chondrosarcoma. The metastasis occurred 7 years after excision of the primary neoplasm. Further investigations revealed no evidence of other metastases. Nevertheless, according to data in the literature, the prognosis has to be considered very poor.

Aged↗
PubMed1994

Capping of bcr-abl antisense oligonucleotides enhances antiproliferative activity against chronic myeloid leukemia cell lines.

Leukemia due to a chromosomal translocation offers an attractive model for the design and testing of antisense agents because the sequence at the translocation junction is unique to the leukemic cell population. Chronic myeloid leukemia is the most common such translocation-induced leukemia. We have found antisense phosphodiester oligonucleotides directed at the bcr-abl junction to be ineffective in inhibiting the growth of CML cell lines. Therefore, we have investigated the effects produced by certain structural modifications of bcr-abl antisense oligonucleotides. For assay purposes we used K562 cells which have the bcr exon 3/abl exon 2 junction and BV173 cells which have the bcr exon 2/abl exon 2 junction. We have found that 5'-capping with a dimethoxytrityl group and 3'-capping with an amino-2-hydroxypropyl group confer antiproliferative activity. The enhancement of activity by capping appears at least partly attributable to exonuclease resistance since stability in serum-containing medium is increased.

Base Sequence↗
PubMed1994

[Portal vein thrombosis: a rare complication of Crohn disease].

Among usual extra digestive manifestations of inflammatory bowel diseases, vascular injuries are rare, but often of excessive gravity. The emergence of a portal thrombosis, often accelerated by infection or traumatism, particularly surgical, remains exceptional. We report the case of a young patient who is followed for a severe crohn's disease and affected with a brutal portal vein thrombosis. Although initial prognosis was bad, the patient now lead a normal life ten months after this episode. It's the third described case of portal thrombosis in crohn's disease. We discuss the predisposing role of an acquired protein S deficiency during a estroprogestative treatment.

Adult↗
PubMed1994

The Provox voice prosthesis and Candida albicans growth: a preliminary report of clinical, mycological and scanning electron microscopic assessment.

Provox voice prostheses are low-resistance speech values available since 1990 for post-laryngectomy voice rehabilitation. Candida spp. mycelial growth has always been a major problem in all prosthetic valves causing leakage and limiting valve life. We found that the Provox new valves were not exempt from the old problem. We performed a preliminary clinical, mycological and scanning electron microscopic assessment of Candida spp. growth on these valves. In contrast to studies done with other valves we found that the Candida mycelium on these new valves was a surface colony rather than growing into the valve substance, thus it might be feasible to control the mycelial growth by either mechanical cleansing or by using topical anti-fungal agents.

Candida albicans↗
PubMed1994

Abnormalities of the p53 MDM2 and DCC genes in human leiomyosarcomas.

In this study we have screened a series of 29 primary leiomyosarcomas for abnormalities of both the p53 gene and the MDM2 gene, which encodes a p53-associated protein. SSCP (single-strand conformation polymorphism) analysis and direct sequencing of polymerase chain reaction (PCR)-amplified DNA were used to establish that 6/29 tumours possessed point mutations of the p53 gene. Using a monoclonal antibody that recognises the p53 protein in immunohistochemical staining experiments, we observed overexpression of the p53 protein in five of the six tumours containing point mutations in the p53 gene. Southern analysis of tumour DNA revealed that 2/29 tumours demonstrated amplification of the MDM2 gene. When considered together, these results indicate that alterations in both the p53 gene and MDM2 gene are important in the development of a significant minority of leiomyosarcomas. In addition, we have demonstrated a significant association between the presence of abnormalities of the p53 gene or MDM2 genes in leiomyosarcomas and a more advanced clinicopathological stage (P = 0.03). We have also examined the role of the DCC tumour-suppressor gene in the development of human soft-tissue tumours in a variety of histological types. Except for evidence of a rearrangement in a single leiomyosarcoma cell line, SK-UT-1, we have found no direct evidence to support a role for mutation of the gene in the development of human soft-tissue tumours.

Adult↗