Carbon adsorption onto Fe oxyhydroxide stalks produced by a lithotrophic iron-oxidizing bacteria.

Iron (Fe)-oxidizing bacteria have the potential to produce morphologically unique structures that may be used as biosignatures in geological deposits. One particular example is Mariprofundus ferrooxydans, which produces extracellular twisted ribbon-like stalks consisting of ferrihydrite, co-located with organic and inorganic elements. It is currently thought that M. ferrooxydans excrete and co-precipitate polysaccharides and Fe simultaneously; however, the cellular production of these polysaccharides has yet to be confirmed. Here, we report on a time-series study that used scanning transmission X-ray microscopy and C 1s and Ca 2p near-edge X-ray adsorption fine structure spectroscopy to investigate production of polysaccharides over the growth cycle of M. ferrooxydans. The production and morphology of twisted iron stalks were consistent with previous observations, but unexpectedly, in the log phase, the carbon content of the stalks was extremely low. It was not until stationary growth phase that a significant component of carbon was detected on the stalks. During the log phase, low levels of carbon, only detectable when the stalks were thin, suggested that M. ferrooxydans produce an extracellular polysaccharide template onto which the Fe precipitates. By stationary phase, the increased carbon association with the stalks was a result of adsorption of organic compounds that were released during osmotic shock post-stalk production. In the environment, elevated concentrations of DOC could adsorb onto the Fe stalks as well as a number of other elements, for example, Si, P, Ca, which, by preventing chemical interactions between the Fe nanoparticles, will prevent structural deformation during recrystallization and preserve the structure of these filaments in the rock record.

The potential role of the Australian Institute of Health and Welfare in a National Cardiac Surgery Database.

The Australian Institute of Health and Welfare has responsibility for developing national health information and collections and is thus a candidate for building and operating a National Cardiac Surgery Database. Many functional characteristics place the Institute in a favourable position for establishing and maintaining a national patient-based database of cardiac surgery. These include its experience in the field of database management, its record of objectivity and its capacity to provide data protection. In addition it has significant experience in monitoring cardiovascular diseases, their risk factors, treatments and outcomes through its National Centre for Monitoring Cardiovascular Disease. The Institute, a statutory body operating within the Federal Government's health portfolio, is independent of policy, administrative and regulatory functions within that portfolio. The health-related databases managed by the Institute include those that record national statistics on insulin-treated diabetes, hospital separations, cancer and death. The Institute also maintains, on behalf of the National Heart Foundation, a cardiac surgery register based on aggregated data from cardiac units. This register is not patient based as the new database would be. With this range of experience, the Institute sees itself well placed to contribute to the development of this important project.

Pleiotropic effects of growth hormone and insulin-like growth factor (IGF)-1 on biological aging: inferences from moderate caloric-restricted animals.

Moderate caloric restriction (60% of ad libitum intake) is an important model to investigate potential mechanisms of biological aging. This regimen has been reported to decrease the number of pathologies and increase life span in all species tested to date. Although moderate caloric restriction induces a wide range of physiological changes within the organism, adaptive changes within the endocrine system are evident and serve to maintain blood levels of glucose. These alterations include an increase in growth hormone secretory dynamics and a decline in plasma levels of IGF-1. These endocrine compensatory mechanisms can be induced at any age, and we have proposed that these alterations mediate some of the beneficial aspects of moderate caloric restriction. Numerous studies indicate that growth hormone and IGF-1 decrease with age and that administration of these hormones ameliorates the deterioration of tissue function evident in aged ad libitum-fed animals, suggesting that the absence of these hormones contributes to the phenotype of aging. Nevertheless, IGF-1 is an important risk factor in age-related pathologies including lung, breast, and prostate cancer. From these studies, we propose that endocrine compensatory mechanisms induced by moderate caloric restriction (including increased growth hormone and decreased IGF-1) decrease the stimulus for cellular replication, resulting in a decline in pathologies and increased life span observed in these animals. These findings have important implications for potential mechanisms of moderate caloric restriction and suggest that neuroendocrine compensatory mechanisms exert a key role on the actions of moderate caloric restriction on life span.

The Drosophila gene asteroid encodes a novel protein and displays dosage-sensitive interactions with Star and Egfr.

The asteroid gene of Drosophila was found to lie within 189 bp of Star. Asteroid cDNA clones were isolated and sequenced and a single putative open reading frame was identified that encodes a novel protein of 815 amino acids with a calculated molecular mass of 93 kilodaltons. Using cDNA probes, asteroid transcripts were localized to the proliferative tissues of embryos and to the mitotically active tissue anterior to the morphogenetic furrow in eye imaginal discs. Ribonuclease protection assays identified a mutation of asteroid that acts as a dominant enhancer of Star mutations and also enhances the Ellipse mutation, EgfrE1. Based on these data, a model for asteroid gene function in EGF receptor signaling is presented.

Dietary intake of Australian smokers and nonsmokers.

The 1983 National Dietary Survey of Adults and the 1983 Risk Factor Prevalence Survey No. 2, conducted on the same subjects, provided an opportunity to examine the nutrient intakes of smokers (1024 men and 785 women) and nonsmokers (1974 men and 2421 women). The nutrients analysed were energy (kJ); fat (g/day and contribution to energy); starch (contribution to energy); dietary fibre (g/day and g/1000 kJ); alcohol (g/1000 kJ); polyunsaturated/saturated fats ratio; cholesterol, niacin, vitamin C, calcium, iron, zinc and magnesium (mg/1000 kJ); and vitamin A, thiamin and riboflavin (microgram/1000 kJ). For both men and women, nonsmokers have a significantly higher intake of starch, dietary fibre (g/day and g/1000 kJ), thiamin, vitamin C, calcium and magnesium than smokers, who have a significantly higher intake of alcohol. Male smokers also have a higher intake of energy and cholesterol, but a lower intake of riboflavin, than nonsmokers. These differences in nutrient intakes suggest that nonsmokers consume a more nutritious diet than smokers, in regard to having a higher intake of fruit and vegetables, wholegrain cereals and milk and milk products. There is a highly statistically significant association between smoking status and hazardous intake of alcohol. Both men and women who smoke have a significantly lower body mass index (BMI), than nonsmokers or ex-smokers.

Receptor-mediated and protein kinase-dependent growth enhancement of primary human fibroblasts by platelet activating factor.

Chronic inflammation is a recognized risk factor for human cancer, but the causal mechanisms are poorly understood. We previously demonstrated that platelet activating factor (PAF) can induce alterations in the in vitro growth properties of primary rat fibroblasts. In the study reported here, exposure of primary human skin fibroblasts to PAF for 1 h in serum-free medium was shown to cause sustained proliferation over 50 d in medium containing low serum and anchorage-independent growth in soft agarose. Both properties could be inhibited by pretreatment with a PAF receptor antagonist, CV3988 (10 microM); a tyrosine-kinase inhibitor, genistein (1 microgram/mL); or a protein kinase C (PKC) inhibitor, staurosporine (50 nM) but not with a cyclooxygenase inhibitor, indomethacin (200 nM-20 microM). PAF had no effect on doubling time, saturation density, or cell viability under normal monolayer growth conditions in complete medium. Treatment with lyso-PAF, an inactive metabolite of PAF, had no effect in either of the assays. Control and PAF-induced cell proliferation in low-serum medium was inhibited by PAF receptor antagonists present during the extended growth period. The presence of PAF receptor mRNA in human skin fibroblasts was demonstrated by reverse transcriptase-polymerase chain reaction. The presence of a functional receptor was indicated by an early (2 min) transient increase in PKC activity and an increase in fos mRNA after PAF treatment. PAF-induced PKC activity was blocked by pretreatment with either staurosporine (50 nM) or CV3988 (1 microM). These results suggest that PAF is a mitogenic factor that contributes to the known increase in risk of malignancy associated with chronic inflammatory conditions.

Effects of androgen deprivation on prostate alpha 1-adrenergic receptors.

OBJECTIVES: Benign prostatic hyperplasia (BPH), the most common benign tumor in men, consists of two components-static (enlargement regulated by androgens) and dynamic (smooth muscle contraction through alpha 1-adrenergic receptors [alpha 1-ARs]). Because medical therapy of BPH involves tissue androgen deprivation, we studied the influence of androgen deprivation and replacement on regulation of rat ventral prostate alpha 1-ARs. METHODS: Prostate weight, alpha 1-AR density, autoradiographic images, histologic features, and cell-specific protein were examined before and after castration and androgen replacement. RESULTS: Castration decreases ventral prostate wet weight, a process reversed by testosterone administration. In contrast, there is an apparent increase in alpha 1-AR density (29 +/- 4 versus 65 +/- 6 fmol/mg total protein, mean +/- SEM) after castration, returning to baseline with testosterone replacement; alpha 1-AR density remains constant in control liver membranes. Alpha 1-ARs predominate in stroma throughout androgen deprivation therapy. Epithelially derived cells decrease (83% to 67%) after castration, resulting in a relative doubling in stroma (17% to 33%); the protein content of epithelial and stromal cells remains identical. Therefore, prostate-specific increases in alpha 1-ARs appear to result from relative increases in the ratio of smooth muscle to epithelium after castration rather than from direct upregulation of alpha 1-AR protein. CONCLUSIONS: Because alpha 1-AR density does not decrease with androgen deprivation, these studies suggest that alpha 1-AR antagonists remain an important component in BPH therapy, even when 5-alpha-reductase inhibitors are utilized.

Decreases in growth hormone receptor signal transduction contribute to the decline in insulin-like growth factor I gene expression with age.

Several investigations have clearly indicated that plasma concentrations of insulin-like growth factor I (IGF-I) decrease with age and contribute to the decrease in tissue function that is characteristic of aging animals and man. Plasma IGF-I is regulated by GH released from the pituitary gland, and although data demonstrate a decline in GH secretion with age, GH receptor (GHR) density in liver tissue has been reported to increase. In this study, the effects of aging on GHR signal transduction were assessed in hepatic tissue to determine whether alterations in the response to GH contribute to the decline in IGF-I. Liver slices from female C57BL/6 mice (10, 17, and 31 months old) were prepared in medium and stimulated with GH. Basal GHR binding increased more than 2-fold in 31-month-old animals compared to that in either 10- or 17-month-old animals (P < 0.01), whereas the Ka values were similar in the three age groups. However, GH (2 nM)-induced IGF-I gene expression decreased dramatically with age (P < 0.01). In 10-month-old animals, GH-induced phosphorylation of the GHR complex was maximal 10 min after the addition of hormone, whereas GH-induced MAP kinase activity was maximal at 15 min. GH-induced JAK2 kinase and GHR complex phosphorylation as well as MAP kinase activity were significantly lower in 31-month-old animals than in either the 10- or 17-month-old groups (P < 0.05). The results of this study demonstrate that GH induces phosphorylation of JAK2 and the GHR complex, activates MAP kinase, and increases the expression of IGF-I messenger RNA in liver. In 17-month-old animals, decreases in IGF-I gene expression were evident that were not directly associated with diminished GHR complex phosphorylation or MAP kinase activity. By 31 months, there was a decrease in IGF-I gene expression that was associated with a marked decline in JAK2 and GHR complex phosphorylation. These data suggest that the signal transduction pathway for GH is impaired with age and that these changes may contribute to the decline in IGF-I gene expression.

Periodic acid-Schiff (PAS)-positive deposits in brain following kainic acid-induced seizures: relationships to fos induction, neuronal necrosis, reactive gliosis, and blood-brain barrier breakdown.

Periodic acid-Schiff (PAS)-positive deposits have been demonstrated in the central nervous system (CNS) of patients suffering from a wide variety of neurodegenerative disorders including Alzheimer's disease, presenile dementia, Parkinson's disease, diabetes mellitus, myoclonic epilepsy, and cerebral palsy. The etiology of these deposits and their relationship to mechanisms of progressive neurodegeneration is unknown. In the present study, we demonstrate that the kainic acid model of limbic status epilepticus provides a useful system for the study of PAS-positive staining. The relationship between PAS-positive deposition, induction of fos-like immunoreactivity (FLI), neuronal necrosis, reactive gliosis, and blood-brain barrier breakdown following the kainic acid induction of status epilepticus was investigated. Epileptiform activity was elicited in rats by intraperitoneal administration of 10 mg/kg kainic acid and brains were examined 3, 5, 12, 24, 72, and 168 h after drug injection. Four distinct types of PAS-positive staining in rat brain were observed: type 1, extracellular matrix (ECM) or blood vessel associated-material; type 2, granular deposits; type 3, glial labelling; and type 4, neuronal labelling. Results demonstrated that the four types of PAS-positive staining were differentially associated with specific markers of neuropathology: (1) type 1 ECM staining and type 3 glia were preferentially localized to edematous tissue; (2) the majority of type 3 glia were identified as reactive astrocytes, while a minority of appeared to be proliferating microglia; (3) type 1 blood vessels labelled hemorrhaging vasculature; (4) early deposition of type 2 granules was predictive of subsequent cell loss; (5) chronic type 2 granular deposits and type 4 neuronal labelling not associated with cell death could be predicted by early changes in FLI; and (6) chronic deposition of all four forms of PAS-positive material was correlated with earlier, transient blood-brain barrier compromise. The results support the growing literature that local carbohydrate metabolism may be one of a constellation of parameters important to the development of progressive neurodegeneration.

Recovery of a rare clone from a population of unstable retroviral vector-expressing mammalian cells using a new RNA extraction and slot-blot protocol.

Although a useful and important method of gene transfer, retroviral vectors can be genetically unstable. In the course of experiments using DOEJS, a retroviral vector able to confer expression of a H-ras oncogene and a neomycin resistance gene (neo) on mammalian cells (Compere et al., 1989), it was found that the vast majority of infected rat embryo fibroblasts, recovered on the basis of neo activity (i.e., G418 resistance), did not express ras mRNA. It was subsequently observed that most cells in the psi 2 cell line used to propagate DOEJS failed to produce virus capable of expressing both ras and neo in primary rat embryo fibroblasts. A simplified RNA extraction and slot-blot technique was developed to screen mRNA from several hundred fibroblast clones and, in doing so, infected fibroblast clones producing both neo and ras mRNA were identified at low frequency. The DOEJS/psi 2 packaging line was subsequently subcloned and individual clones screened for their ability to confer appropriate gene expression on target cells. Subclone DOEJS/psi 2-B6 was eventually isolated after screening 24 DOEJS subclones and 240 infected rat embryo fibroblast colonies. DOEJS/psi 2-B6 was shown to induce reliably phenotypic transformation, G418 resistance, and ras and neo mRNA expression in primary rat embryo fibroblasts. The RNA extraction and screening procedure was thus useful for recovering an infrequent subclone producing a retrovirus with the original properties.

Trends in cardiovascular risk factors in Australia. Results from the National Heart Foundation's Risk Factor Prevalence Study, 1980-1989.

OBJECTIVES: To examine recent changes in the cardiovascular risk factor profile of Australian adults and to compare these with trends in mortality. DESIGN: Questionnaire and examination data collected from multicentre cross-sectional surveys conducted in 1980, 1983 and 1989. SUBJECTS: 19,315 randomly selected respondents aged 25-64 years living in the six State capital cities. RESULTS: During the 1980s, average blood pressure levels declined in all age groups and for both men and women. The prevalence of hypertension decreased and it appeared to be more effectively managed. Total cholesterol levels decreased significantly in younger men and older women but lipid results showed no overall favourable trend. Weight for height increased in all ages, strongly suggesting increased body fatness. In women, the odds of being overweight or obese increased by 58%, and in men by 23%. The prevalence of smoking declined significantly in men and women. Cessation of smoking and decreased uptake both contributed to the decline in men, while smoking cessation was more important in women. Consumption of alcohol declined significantly in both sexes. Adding salt to food became less common, as did eating the fat on meat. Walking for recreation or exercise and other forms of less vigorous exercise became more popular, while the prevalence of aerobic exercise and vigorous exercise remained unchanged. CONCLUSIONS: Reductions in cigarette smoking and blood pressure are likely to have contributed to the falls that have been noted in cardiovascular mortality rate. Changes in dietary behaviour were consistent with health education messages. The trend towards greater body fatness may retard the benefits of favourable trends in other cardiovascular risk factors, morbidity and mortality and requires greater attention.

Immunoselection of GRP94/endoplasmin from a KNRK cell-specific lambda gt11 library using antibodies directed against a putative heparanase amino-terminal peptide.

Induction of an invasive phenotype by metastatic tumour cells results in part from inappropriate expression of extracellular matrix-degrading enzymes normally involved in embryonic morphogenesis, tissue remodelling, angiogenesis and wound healing. Such enzymes include endoglycosidases that degrade heparan sulfate (HS) in endothelial basement membrane, as well as better characterized proteases. Heparanase, an endo-beta-D-glucuronidase initially detected in B16 melanoma cells, has been described as a M(r) 96,000 glycoprotein with pI of 5.2, and has been immunolocalized to the cell surface and cytoplasm. We have utilized a polyacrylamide-gel-based HS degradation assay to demonstrate that KNRK, a rat kidney fibroblast cell line transformed by v-K-ras, exhibits HS-degrading activity similar to that of B16F10 mouse melanoma cells. To immunoselect heparanase-expressing clones from a KNRK-cell-specific lambda gt11 cDNA library, we have also prepared a rabbit anti-serum directed against a putative amino-terminal peptide of B16F10 cellular heparanase. Lysogens from one clone expressed a beta-galactosidase fusion protein whose staining with peptide anti-serum was inhibited by competition with excess peptide. Dideoxy-mediated sequencing of the insert termini of this recombinant revealed that it represents a rat homologue of M(r) 94,000 glucose-regulated protein (GRP94/endoplasmin), a molecular chaperone that contains the exact amino-terminal sequence previously attributed to heparanase. Our results call into question the specificity of this peptide sequence, as well as previous immunolocalization studies of heparanase carried out using such anti-sera.

Inequalities in risk factors and cardiovascular mortality among Australia's immigrants.

Inequalities in biomedical and life-style risk factors for cardiovascular disease were examined for 6,116 immigrants to Australia and 14,941 people born in Australia, using data collected in the 1980, 1983 and 1989 risk-factor prevalence surveys. After adjusting for age and study design, significant differences were identified between immigrant groups and the Australian-born reference group, particularly for systolic blood pressure, overall obesity and behavioural risk factors. There were few substantial differences in blood lipid concentrations and little evidence to suggest that total plasma cholesterol has played a major role in lower cardiovascular mortality among immigrants. Overall, the results suggested that profiles of risk factors commonly accepted as determinants of cardiovascular disease are an insufficient explanation of the lower standardised mortality ratios from cardiovascular disease which characterise immigrants in Australia. Systolic blood pressure best explained variation in cardiovascular mortality among male immigrants, and smoking prevalence among female immigrants. The acculturation process affected immigrant groups differently. Generally, systolic blood pressure increased with period in Australia. Body mass index increased among Asian immigrants, as did participation in physical activity during leisure time.

Platelet activating factor, an endogenous mediator of inflammation, induces phenotypic transformation of rat embryo cells.

The ability of platelet activating factor (PAF), a potent endogenous inflammatory agent, to induce phenotypic transformation of primary rat embryo cells (RECs) was investigated. RECs are composed predominantly of fibroblasts, with some epithelial cells and a few neuronal and muscle cells. A 1 h period of treatment with PAF (1 x 10(-8)-1 x 10(-6) M) increased the ability of RECs to (i) form foci, (ii) reach a high saturation density in complete medium, (iii) grow in low serum-containing medium and (iv) exhibit anchorage-independent (AI) growth. Similar changes were achieved with C-PAF (1 x 10(-10)-1 x 10(-8) M), an active, non-metabolizable analog of PAF, but not by lyso-PAF (1 x 10(-10)-1 x 10(-6) M), a biologically inactive metabolite of PAF. All of the PAF-induced phenotypic changes could be inhibited by pretreatment with a PAF receptor antagonist, CV3988 (1 x 10(-6) M). Pretreatment of RECs with genestein (1 microgram/ml) also completely inhibited all four measures of PAF-induced REC transformation indicating that tyrosine kinase activity may be required for the observed changes in phenotype. Pretreatment with indomethacin (2 x 10(-7) M) blocked the PAF-induced increases in focus formation and saturation density without affecting PAF-induced alterations in growth in low serum or AI growth. This indicates that PAF may exert some of its effects through a cyclooxygenase product. Pretreatment with staurosporine (5 x 10(-8) M) failed to alter any of the PAF-induced effects, suggesting that protein kinase C activity is not involved in REC transformation by PAF. Our results provide the first evidence that PAF, released by activated phagocytes in and around areas of inflammation, may contribute to the process of malignant transformation.

Iron status of Australian children.

A national survey covering all States and Territories was conducted in urban and rural schools to determine the iron status of Australian children and adolescents. This article reports the results of blood analyses for 1696 schoolchildren aged 9, 12 and 15 years. The measures of iron status analysed were plasma levels of iron, transferrin and ferritin. Results for all of these measures were available for 1204 of the schoolchildren for whom iron status was assessed based on the plasma ferritin and transferrin saturation model. Iron status was generally satisfactory in the 9, 12 and 15 year old boys and the 9 and 12 year old girls. There was a marked and statistically significantly higher prevalence of iron deficiency among the 15 year old girls. These results are discussed in relation to the food and nutrient intakes of 12 and 15 year old children who also participated in the 1985 National Dietary Survey of Schoolchildren.

Education level and coronary risk factors in Australians.

There is an inverse association between social class ranking and mortality from coronary heart disease in Australia and in some other countries. To explain whether this association is related to differences in risk factors, the relationship between coronary risk factors and the highest level of education completed was explored for a reasonably representative cross-section of the adult Australian population. After adjustment for the effects of age, relative weight and alcohol intake, blood pressure was found to vary inversely with education level in both sexes. In men only plasma cholesterol, triglycerides and high density lipoprotein cholesterol levels showed no significant variation with education level. In women, plasma triglycerides and high density lipoprotein cholesterol levels varied inversely with education level after adjustment. There was less cigarette smoking among more highly educated men but no clear smoking trends among women. The findings broadly confirm the results of similar analyses which used occupation as the measure of social class and have implications for future community education programmes in that present strategies may be inappropriate for less highly-educated members of society.

Intraperitoneal penetration of cefotetan.

The intraperitoneal penetration of cefotetan was studied after a 1-g intravenous injection in 25 patients undergoing elective gastrointestinal surgery. Levels of peritoneal fluid were high within 10 min after administration and increased to 44% of the serum levels after 30 min, rising to 115% at 3 h. The mean concentration of cefotetan between 3 and 5 h after administration was 32.3 micrograms/ml. These findings suggest that 1 g of cefotetan administered before abdominal surgery would result in intraperitoneal cefotetan levels necessary to inhibit susceptible pathogens for 5 h or more.

Colorectal cancer. A study of 230 patients.

Clinical presentation, risk factors, investigations, pathology and treatment were examined in a retrospective review of 230 patients with colorectal cancer. Many patients presented with symptoms not usually associated with colorectal cancer, such as pain in the upper part of the abdomen, and rectal bleeding separate from the stool. Iron deficiency anaemia was an uncommon presentation. Over all, one-third of patients had at least one risk factor for colorectal cancer. Risk factors such as adenomatous polyps and family history of colorectal cancer were more common than inflammatory bowel disease and polyposis coli. Although a delay in diagnosis was recorded in one-quarter of patients, the finding of a negative correlation between duration of symptoms and extent of spread suggests that the length of the symptomatic illness is not an important factor in prognosis. Contrary to surgical and medical teaching, only 43% of cancers were in the rectum and rectosigmoid area, and, hence, within reach of the standard sigmoidoscope. Surgical resection was performed in 76% of patients. Forty-three per cent of patients who underwent surgery developed at least one postoperative complication resulting in a longer stay in hospital.