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Biomedical subjects

J G Smith

Publications and source records attributed to J G Smith.

At least 19 recordsLinked to original sources
PubMed1992

Phenoxy herbicides and chlorophenols: a case control study on soft tissue sarcoma and malignant lymphoma.

A case control study on patients with soft tissue sarcoma and malignant lymphoma was undertaken to test whether there was any association between these diseases and past exposure to chlorinated phenoxy acid herbicides or chlorophenols. It was carried out over the period 1982-1988 in Victoria, Australia. Thirty males with soft tissue sarcoma and 52 males with malignant lymphoma were matched by age, place of residence and sex with one population control and one cancer control each. Exposure was assessed by personal interviews conducted by an occupational hygienist. Exposures within 5 years prior to diagnosis of each matched case were ignored, both for the cases and their matched controls. The estimated relative risks for definite or probable exposure to chlorinated phenoxy compounds or chlorophenols for at least 1 day were 1.0 (95% confidence interval (CI): 0.3-3.1) for soft tissue sarcoma and 1.5 (95% CI: 0.6-3.7) for malignant lymphoma. When the criterion for exposure was raised to more than 30 days, the estimated relative risks were 2.0 (95% CI: 0.5-8.0) for soft tissue sarcoma and 2.7 (95% CI: 0.7-9.6) for malignant lymphoma. Additional analyses were carried out for exposure of at least 1 day to phenoxy herbicides alone or chlorophenols alone. None of the estimated relative risks was significantly greater than unity.

Adult↗
PubMed1992

Assessment of potential doses at the Maralinga and Emu test sites.

An assessment has been undertaken of potential doses to future aboriginal inhabitants of the Maralinga and Emu areas of South Australia, where nuclear weapons tests in the 1950s and 1960s have resulted in residual radioactive contamination. Radioactive material due to this program of tests and other experiments is still detectable several tens of kilometers from some of the test sites. Continued occupancy by individuals following an Aboriginal lifestyle could give rise to annual effective dose equivalents of several mSv within contours enclosing areas of several hundred square kilometers. The most significant dose pathways are calculated to be the inhalation of resuspended activity and ingestion of soil by infants. An analysis of the effects of uncertainties in the dose calculation has indicated the uncertainty distribution on predicted doses from the inhalation pathway.

Adult↗
PubMed1992

Chlamydia trachomatis pneumonia induces in vivo production of interleukin-1 and -6.

Cytokine induction during Chlamydia trachomatis pneumonia may alter the pathogenesis or course of disease. We examined interleukin-1 (IL-1) and IL-6 production by measuring mRNA and bioactivity in murine lungs. mRNA and bioactivity for IL-1 alpha, IL-1 beta, and IL-6 increased after Chlamydia infection. These cytokines may be important in regulating host defenses against C. trachomatis.

Animals↗
PubMed1992

Structured approach to the investigation of anaemia in patients with rheumatoid arthritis.

A group of 28 patients with rheumatoid arthritis who were severely anaemic were investigated for iron deficiency. On the basis of bone marrow studies, the patients were divided into two groups, those with and those without signs of stainable iron in the marrow. This grouping did not distinguish between the severity of their rheumatoid arthritis measured by clinical parameters. Measurement of the red cell count and biochemical parameters in the peripheral blood showed a statistical difference in red cell size, haemoglobin content, and iron binding capacity between the two groups. The statistical variation of these parameters, however, did not allow these measurements to predict bone marrow iron deficiency in any subject. Investigation of the upper gastrointestinal tract by endoscopy showed that acute macroscopic lesions were infrequently associated with anaemia. It was concluded that anaemia in association with rheumatoid arthritis may mimic iron deficiency anaemia, and that simple investigations of the peripheral blood do not accurately show the iron status of the reticuloendothelial system in the presence of a chronic inflammatory disease. For the investigation of severe anaemia in rheumatoid arthritis, bone marrow assessment of iron status should be performed as the initial investigation. In addition, iron deficient patients require investigation of the lower and the upper gastrointestinal tract.

Administration, Oral↗
PubMed1992

Anaemia of chronic disease in rheumatoid arthritis: effect of the blunted response to erythropoietin and of interleukin 1 production by marrow macrophages.

Anaemia in rheumatoid arthritis (RA) is a common and debilitating complication. The most common causes of this anaemia are iron deficiency and anaemia of chronic disease. Investigations have suggested that interleukin 1 (IL-1) or tumour necrosis factor (TNF), or both, from monocytes associated with chronic inflammation are responsible for the anaemia of chronic disease. On bone marrow examination anaemia of chronic disease is characterised by the diversion of iron from the erythropoietic compartment into marrow macrophages. This phenomenon is termed failure of iron utilisation. In this study, CFU-E (colony forming unit erythroid; late red cell precursors) and BFU-E (burst forming unit erythroid; early red cell precursors) stem cells were cultured from 10 normal marrow samples and 12 marrow samples from patients with RA with iron deficiency anaemia and 10 samples from patients with RA with failure of iron utilisation. All patients with RA were anaemic (haemoglobin less than 100 g/l), Potential accessory or inhibitory cells of erythropoiesis (CD4, CD8, or CD14 positive cells) were removed before culture. Control marrow samples were studied in a similar manner. Normal marrow samples yielded 377 (17) CFU-E and 133 (6) BFU-E (mean (SD)) colonies for each 2 x 10(5) light density cells plated. CD4 ablation caused reductions of 62 and 100% in CFU-E and BFU-E colonies respectively. CD14 removal resulted in considerable but lesser reductions of 46% for CFU-E and 25% for BFU-E. In both groups of patients with RA, CFU-E colony numbers were significantly lower than those seen in normal control subjects, 293 (17) for patients with iron deficiency anaemia and 242 (35) for patients with failure of iron utilisation. BFU-E colony numbers were 102 (13) and 108 (20) respectively. In patients with RA, CD4 removal caused a significantly greater loss of CFU-E colonies compared with normal control subjects. Cytolysis of CD14 positive cells caused a reduction in CFU-E colonies in the two RA groups which was similar to that seen in normal subjects. In conclusion, patients with RA seem to have fewer CFU-E progenitors but essentially normal numbers of BFU-E stem cells. Our data suggest a stimulatory role for marrow CD4 and CD14 cells in erythropoiesis in patients with RA. Monocytes-macrophages (CD14 positive) are known to be producers of IL-1 or TNF, or both, however, the predicted increase in the CFU-E colonies on removal of CD14 cells is not seen. Therefore, if IL-1 or TNF, or both, are responsible for the impairment of erythropoiesis in patients with RA, marrow macrophages are unlikely to be the source. Moreover, these results indicate the probability of erythropoietin resistance on the basis of diminished CFU-E colony formation in patients with RA.

Anemia↗
PubMed1992

Responses of peripheral blood cells to acute insulin-induced hypoglycaemia in humans: effect of alpha-adrenergic blockade.

Acute hypoglycaemia provokes rapid changes in peripheral blood cell counts. To examine possible adrenergic mechanisms modulating these changes, counts of peripheral blood cells including lymphocytes, granulocytes and red cells were measured in response to acute hypoglycaemia in a group of six normal subjects in control conditions (study 1), and during alpha-adrenergic blockade with phentolamine (study 2). In study 1 hypoglycaemia provoked a biphasic white cell response, with an early rise in lymphocyte count and a later rise in granulocyte count. The red cell count increased modestly following hypoglycaemia. During alpha-adrenergic blockade, the rise in total white cell count was diminished, with the rise in the lymphocyte count being greatly obtunded. The rise in the granulocyte count was unchanged. The increment of the red cell count during acute hypoglycaemia was abolished. These findings suggest that the increments of peripheral lymphocyte and red cell counts in response to acute insulin-induced hypoglycaemia are mediated via alpha-adrenoreceptors.

Acute Disease↗
PubMed1991

The occurrence subtype and significance of haemopoietic inhibitory T cells (HIT cells) in myelodysplasia: an in vitro study.

This study examines the occurrence, subtype and possible significance of haemopoietic inhibitory T cells (HIT cells) in patients with myelodysplasia (n = 21), acute myeloblastic leukaemia (n = 8) and in normal subjects (n = 13) using an autostimulary CFU-GM stem cell assay. HIT cells were detected when colony numbers increased by 30% or more following T-lymphocyte subpopulation ablation. HIT cells occurred in 28% of the MDS patients, were always CD8-positive and never occurred in the normal subjects. Sequential studies in MDS patients with HIT cells and treated with low dose Ara-C showed no correlation between occurrence of these cells and clinical outcome. HIT cells appear to be a clinically irrelevant manifestation of the cell dysfunction associated with MDS.

Cytarabine↗
PubMed1991

Propylene glycol dermatitis.

Propylene glycol is a commonly used vehicle for topical preparations. Although it is well suited for this purpose, it is capable of producing both primary irritant skin reactions and allergic sensitization. The literature on propylene glycol is reviewed, with particular attention to the nature of these adverse cutaneous effects. Guidelines for patients sensitive to propylene glycol are discussed.

Administration, Cutaneous↗
PubMed1990

The myelodysplastic syndromes. Case report and review.

The myelodysplastic syndromes are a heterogenous group of hematologic disorders of myeloid progenitor cells. Oral manifestations may be among the first signs and often reflect degrees of neutropenia or neutrophil dysfunction. A patient with persistent herpes labialis and severe oral mucosal ulceration in myelodysplastic syndrome is reported. The features of myelodysplasia are reviewed and their oral manifestations and significance to dental management outlined.

Acyclovir↗
PubMed1990

Cytosine arabinoside does not cause differentiation in vitro of CFU-GM in marrow from normal, myelodysplastic or ANLL subjects.

This study examines the effect of cytosine arabinoside (Ara-C) on CFU-GM progenitor cells grown in methylcellulose culture from normal and myelodysplastic subjects and patients with acute non-lymphoblastic leukaemia. Light density marrow cells were incubated during culture with Ara-C concentrations ranging from 10(-4) M to 10(-12) M. After counting, colonies were cytospun and cells within the colonies examined for alkaline phosphatase positivity and expression of HLA-DR antigen, as indices of differentiation. Monocytes/macrophages were also enumerated in colonies using the monoclonal antibody CD14. In all subjects, 10(-4) M to 10(-6) M Ara-C caused significant reduction in CFU-GM colony formation compared with control (no Ara-C). In no instance did colony numbers increase. Ara-C across the dose curve had no effect on myeloid differentiation markers in any of the groups studied. Similarly, percentages of CD14 positive cells in colonies were not altered by exposure to Ara-C. Using this clonogenic model, these data suggest that Ara-C does not induce differentiation of CFU-GM stem cells in normal subjects or patients with myelodysplasia/acute non lymphoblastic leukemia.

Alkaline Phosphatase↗
PubMed1990

Tumor necrosis factor-alpha plays a role in host defense against Histoplasma capsulatum.

Tumor necrosis factor-alpha was detected in supernatants collected from BALB/c mouse peritoneal macrophages incubated continuously with Histoplasma capsulatum. The levels of TNF alpha measured by actinomycin D bioassay peaked within hours after exposure and then greatly declined by 24 h. TNF alpha was also measured in bronchoalveolar lavage fluid from BALB/c mice challenged intranasally with H. capsulatum. Lavage fluid TNF alpha levels exhibited the same pattern as the in vitro supernatants; they peaked within hours after challenge and lower levels were detected at 24 h. Treatment of mice with anti-TNF alpha antibody accelerated mortality in response to systemic infection and significantly increased tissue colony counts in the liver and spleen. In the murine model, TNF alpha is produced in response to H. capsulatum and appears to play some role in host defense to infection.

Animals↗
PubMed1990

Late recurrence of localized cutaneous melanoma: its influence on follow-up policy.

This paper reports 11 cases of recurrence 10 years or more after primary treatment of clinically local cutaneous melanoma at the Peter MacCallum Cancer Institute. Using the product-limit method for estimating recurrence-free survival, two late recurrence rates have been calculated. The estimated late recurrence rate among all treated patients is 5 percent (95 percent confidence interval: 2 to 8 percent), and the estimated late recurrence rate for the group who survived the first 10 years without recurrence is 7 percent (95 confidence interval: 3 to 11 percent). No prognostic factors were found that could identify a patient subgroup significantly at risk of late recurrence. Recurrence-free survival curves show that most recurrences have presented by the end of 6 years, but later recurrences are seen, the latest in this series being 18.2 years following treatment. While patients probably do not require long-term follow-up in specialist clinics provided they are adequately educated in the nature of their disease, this paper shows the value of long-term statistical surveillance.

Female↗
PubMed1990

The effect of alpha-adrenergic blockade on responses of peripheral blood cells to acute insulin-induced hypoglycaemia in humans.

Acute hypoglycaemia provokes rapid changes in peripheral blood cell counts. To examine possible adrenergic mechanisms modulating these changes, counts of peripheral blood cells including lymphocytes, granulocytes and erythrocytes were measured in response to acute hypoglycaemia in a group of six normal subjects in control conditions (study 1), and during alpha-adrenergic blockade with phentolamine (study 2). In study 1 hypoglycaemia provoked a biphasic leucocyte response, with an early rise in lymphocyte count and a later rise in granulocyte count. The erythrocyte count increased modestly following hypoglycaemia. During alpha-adrenergic blockage, the rise in total leucocyte count was diminished, with the rise in the lymphocyte count being greatly obtunded. These findings suggest that the increments of peripheral lymphocyte and erythrocyte counts in response to acute insulin-induced hypoglycaemia are mediated via alpha-adrenoreceptors.

Adult↗
PubMed1990

A role in vivo for tumor necrosis factor alpha in host defense against Chlamydia trachomatis.

In a mouse model of pneumonia caused by murine Chlamydia trachomatis (mouse pneumonitis agent [MoPn]), tumor necrosis factor alpha (TNF-alpha) antigen and bioactivity were demonstrated in vivo in the lung during MoPn infection in both athymic (nude) and heterozygous (nu/+) mice. Antibody to TNF-alpha that was exogenously given neutralized the TNF-alpha in the lung, significantly accelerated mortality, and caused a borderline increase in MoPn counts in the lung by culture in nu/+ mice. Lipopolysaccharide-induced TNF-alpha activity or injections of recombinant murine TNF-alpha significantly but modestly protected nu/+ mice against MoPn-induced mortality. TNF-alpha is produced in vivo during C. trachomatis infection and plays a role in host defense.

Animals↗