Organic thiols are toxic to eukaryotic cells. Treatment of cells with thiols activates expression of grp78, but it is not known if, like other forms of stress, there is a battery of stress response genes that are induced by thiols. In LLC-PK1 renal epithelial cells, mRNAs for both grp78 and gadd153 were induced by thiols with similar time, concentration and structure-activity dependence. Dithiothreitol (DTT) was the most potent reductant and inducer of gene expression among the thiols tested. Nuclear run-on assays demonstrated that DTT activated both grp78 and gadd153 genes transcriptionally. A hamster gadd153 promoter construct which contains enhancer elements necessary for gadd153 activation was stably integrated into the LLC-PK1 cell genome and was activated by DTT. Although auto-oxidation of thiols can generate active oxygen species, transcriptional activation of the gadd153 promoter was not due to formation of hydrogen peroxide or superoxide since neither catalase nor superoxide dismutase prevented activation of the gadd153 promoter by DTT. The concentration dependence for activation of the gadd153 promoter correlated with inhibition of dome formation and protein synthesis, two toxic effects of DTT in LLC-PK1 cells. Thus, both grp78 and gadd153 are members of a gene battery which is responsive to reductive stress. There appears to be considerable, but not complete, overlap between the upstream signaling pathways for activation of both genes.

Animals↗

PubMed1996

Spatial and temporal relationships between Shh, Fgf4, and Fgf8 gene expression at diverse signalling centers during mouse development.

During limb outgrowth, Shh, Fgf4, and Fgf8 act as signals controlling limb growth and patterning. Because these genes are expressed in the limb bud and other known signalling centers, we have explored the relationships between the expression of these during mouse development using double in situ hybridization. Within the node and limb bud the expression domains of these genes contact each other, whereas in the floor plate the Fgf8 expression domain does not contact that of Shh. The relative temporal order of gene expression varies in different centers. The spatial and temporal expression of Fgf4, Fgf8, and Shh suggests that conservation of molecular mechanisms in different organizing centers as well as differences between them.

Animals↗

PubMed1996

Double in situ hybridization on mouse embryos for detection of overlapping regions of gene expression.

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Animals↗

PubMed1996

Role of catechol siderophore synthesis in Vibrio vulnificus virulence.

We isolated a Vibrio vulnificus TnphoA mutant that was unable to produce catechol siderophores or to acquire iron from transferrin. This mutant showed reduced virulence in an infant mouse model. The TnphoA insertion was in an open reading frame designated venB. The venB gene cloned on a plasmid restored catechol production to the mutant. The deduced amino acid sequence of venB is 41% identical to the enzyme isochorismatase of Escherichia coli (EntB), an enzyme involved in the biosynthesis of the catechol siderophore enterobactin.

Amino Acid Sequence↗

PubMed1996

Transcription start sites downstream of the Epstein-Barr virus (EBV) Fp promoter in early-passage Burkitt lymphoma cells define a fourth promoter for expression of the EBV EBNA-1 protein.

In Epstein-Barr virus (EBV)-transformed B lymphoblastoid and many Burkitt lymphoma cell lines, the EBV EBNA-1 protein is one of six viral nuclear antigens expressed from a common transcription unit under the control of one of two promoters, Wp or Cp. In contrast, EBNA-1 is the only EBV nuclear antigen expressed in Burkitt and other EBV-positive tumors. We previously identified a promoter of EBNA-1 transcription, designated Fp, in early-passage Mutu Burkitt tumor cells, and this promoter is also active in long-term Mutu and Akata Burkitt cell lines which maintain the exclusive expression of EBNA-1 characteristic of the tumor. However, transcription initiation within Fp reporter gene plasmids in EBV-negative cells occurs at positions 100 to 200 bases downstream of the Fp start site in the BamHI-Q restriction fragment. Here we demonstrate that transcription initiation within newly established Burkitt lymphoma cell lines is consistent with the transcription initiation we observed in reporter plasmids. Furthermore, previous observations of transcription from Fp to generate EBNA-1 transcripts can be attributed to lytic-cycle gene expression. These data, in conjunction with our previous characterization of promoter regulatory elements, define a fourth EBNA-1 promoter, Qp, that is active in latently infected Burkitt tumor cells.

Antigens, Viral↗

PubMed1995

Epstein-Barr virus isolates with the major HLA B35.01-restricted cytotoxic T lymphocyte epitope are prevalent in a highly B35.01-positive African population.

An influence of cytotoxic T lymphocyte (CTL) response over Epstein-Barr virus (EBV) evolution was first suggested by the finding that virus isolates from highly HLA-A11-positive Oriental populations were specifically mutated in two immunodominant A11-restricted CTL epitopes. Here we turn to a second HLA allele, B35.01 and show that B35.01-restricted CTL responses in Caucasian donors reproducibly map to a single peptide epitope, YPLHEQHGM, representing residues 458-466 of the type 1 EBV nuclear antigen 3A protein (B95.8 strain). In this case, however, most EBV isolates from a highly B35.01-positive population (in The Gambia) either retained the CTL epitope sequence or carried a mutation (P-->S at position 2) which conserved antigenicity; changes leading to reduced antigenicity (Y-->N at position 1) were found in only a minority of cases. Furthermore, CTL recognizing the YPLHEQHGM epitope could be reactivated from the blood of some B35.01-positive Gambian donors by in vitro stimulation with the synthetic peptide, indicating that epitope-specific immunity does exist in this population. Possible differences between the A11-based and B35.01-based studies are discussed.

Amino Acid Sequence↗

PubMed1995

Ethnic minorities, health care systems, and behavior.

This article presents an overview of research on health care use and provider behavior, on doctor-patient relationships, adherence to medical regimens, self-care, practices and avoidance health care behaviors, and attitudes of 4 ethnoracial groups: African Americans, American Indians, Asian Americans, and Latinos. Although issues within the groups varied, common themes between the groups emerged. It became apparent, after discussion, that whatever the issues and health problems, these can be resolved most effectively when addressed within the social contexts of each ethnoracial group.

Black or African American↗

PubMed1995

A retrospective cohort study of childhood immunisation status in northern Sydney.

A survey of their children's immunisation status was conducted among mothers of babies from a three-month birth cohort (January to March 1990) in the Northern Sydney Area in 1992. Its aims were to determine the uptake of immunisation in the area, to examine factors associated with immunisation status, and to assess agreement between the parent's reporting of this status and records of councils and general practitioners. Fifty-eight per cent of the questionnaires (1004) were returned. The full immunisation rate was 86 per cent, 14 per cent were partially immunised and only four children had received no immunisations. Between 74 per cent and 82 per cent of vaccinations were on time at two, four and six months; the rate dropped to 21 per cent at 12 months. Logistic regression analysis showed that premature babies are significantly more likely to be fully immunised, whereas children who have had a serious childhood illness, those with a single mother, or whose mothers are more highly educated, are significantly less likely to be fully immunised. There was 60 per cent agreement between the parent's report of immunisation status and a subgroup of 197 council and 82 general practitioner records. Although all councils in the Northern Sydney Area have a reminder system, most immunisations were found to be done in general practices (64 per cent), where reminder systems are not common.

Child, Preschool↗

PubMed1995

The natriuretic effect of lithium in man: is the proximal tubule involved?

The possible role of the proximal tubule in the natriuresis which follows the administration of small doses of lithium, as used in lithium clearance studies, was investigated in 12 healthy males on a fixed sodium intake. Subjects were given placebo tablets, or 100 mg or 600 mg of lithium carbonate; renal function was assessed 3-6 h later. The 600-mg dose of lithium carbonate caused a 50-60% increase in sodium excretion, whereas the 100-mg dose was without effect. Creatinine clearance, used as an index of glomerular filtration rate, was unaffected by either dose. Three indices of end-proximal fluid delivery were used simultaneously: urine flow rate during suppression of vasopressin secretion (Vmax), phosphate clearance and lithium clearance (the latter only on the days on which lithium was administered). No effect of either dose of lithium on Vmax or phosphate clearance was evident; nor was there a difference between values for lithium clearance following the two doses. We conclude that administration of the standard 600-mg test dose of lithium carbonate does not affect proximal tubular function.

Adult↗

PubMed1995

Biomedical image processing in pathology: a review.

Pathologists make a diagnostic decision by viewing a specimen and measuring various diagnostically important attributes of an isolated object such as size, shape, darkness, colour and texture. This is a complex process. In recent years, computer-aided image processing and analysis systems have played a significant role in quantitative pathology. This paper summarises basic image processing and analysis techniques and reviews related work in pathology and cytology based on computational image processing since 1987. Firstly, we present a general introduction to image enhancement, segmentation, morphometry and visualisation for those medical colleagues who may not have the necessary background in this area. (The mathematical treatment is kept to minimum and appropriate references are cited to satisfy the more mathematically oriented readers. Selected examples are provided to demonstrate the effects of various basic image processing algorithms on a MRI scan. It should be emphasised that the reviewed techniques are generally used as preprocessing steps in analysing microscopic images and powerful algorithms are more sophisticated and problem-specific.) Secondly, we review image cytometric and histometric methods, standards, calibration and applications. Finally, we touch upon three dimensional confocal image processing and analysis, applications of artificial neural networks, and optical disk database management for recording and retrieving a large number of digitised high resolution images. The development of integrated optical microscope and computer, systems is also briefly described.

Artificial Intelligence↗

PubMed1995

Cytokine receptor expression by solid tumours.

The expression of cytokine receptors by a variety of solid tumour tissues was examined, using an immunofluorescence procedure optimized for sensitivity. Several cytokines generally considered as relevant only to the immune and haematopoietic systems were shown to be expressed by solid tumours. For example, breast carcinoma frequently expressed both chains of the IL-3 receptor, the beta chain of the IL-2 receptor, the TNF type two receptor, the signal-transducing chain CD130, and c-kit. The broad expression of cytokine receptors suggests that the receptor profile of individual tumours should be determined before the application of therapy that involves the administration of cytokines.

Breast Neoplasms↗

PubMed1994

What do stochastic frontier cost functions tell us about inefficiency?

Recent studies using the stochastic frontier approach have suggested high levels of inefficiency in nursing home and hospital facilities. This paper makes two observations. First, one could falsely estimate high levels of inefficiency if a statistical assumption--zero skewness of the random component of the cost residual--is violated. Second, an inefficient industry may be difficult to distinguish either statistically or visually from an industry free of inefficiency. If available, panel data yields more robust estimates of cost differences among nursing homes or hospitals.

Costs and Cost Analysis↗

PubMed1994

The effect of chronic sodium depletion on renal function in conscious rats.

In order to investigate the effect of chronic sodium depletion on renal proximal tubular reabsorption, studies were performed in conscious, unrestrained Brattleboro rats. Since these animals lack circulating vasopressin, fractional water reabsorption in the distal nephron can be assumed to be constant and changes in urine flow rate should therefore reflect changes in end-proximal fluid delivery. Sodium depletion was induced by placing rats on a low-sodium diet (4 mmol Na (kg dry wt)-1) and administering frusemide (40 mg (kg body wt)-1) by gavage on the first 2 days. Extracellular volume, measured after 7-9 days, was reduced by 19% (P < 0.02) as compared with that of rats maintained on a control diet. Urine flow rate, measured during days 4-7 of the low-sodium diet, was significantly lower than that of control rats (142 +/- 8 vs. 168 +/- 5 ml day-1, P < 0.01). Since renal papillary interstitial fluid osmolality was found to be reduced in the sodium-depleted rats (693 +/- 38 vs. 812 +/- 36 mosmol (kg H2O)-1, P < 0.05), it is unlikely that water reabsorption from sites beyond the proximal tubule had increased. The observed reduction in urine flow rate therefore strongly suggests a reduction in end-proximal fluid delivery. In the second part of the study, a single group of Brattleboro rats was used, in which osmotic minipumps were implanted in the peritoneal cavity for continuous infusion of [14C]inulin. After recovery from the operation, the rats were maintained on a control diet for 6 days (pre-control period), then subjected to sodium depletion (low-sodium diet for 6 days, frusemide administration on the first 2 days), and finally returned to the control diet for 6 days, with access to 0.46 M NaCl solution on the first 2 days, in order to restore sodium balance (post-control period). On the final 2 days of each phase, urine flow rate and [14C]inulin clearance (= glomerular filtration rate, GFR) were measured. Urine flow rates during the pre-control, sodium depletion and post-control periods were 169 +/- 7, 132 +/- 8 (P < 0.001) and 176 +/- 8 microliters min-1, respectively; corresponding values for fractional water excretion were 7.0 +/- 0.3, 6.0 +/- 0.5 (P < 0.01) and 7.4 +/- 0.4%. Only a small reduction GFR, of borderline statistical significance, was observed during sodium depletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗

PubMed1993

Steroid tapering in acute asthma.

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Acute Disease↗