An Australian study to evaluate worker exposure to chrysotile in the automotive service industry.

A study was conducted in Sydney, Australia, in 1996 to investigate the current exposure levels, control technologies, and work practices in five service garages (four car and one bus), three brake bonding workshops, and one gasket processing workshop. This study formed part of the assessment of chrysotile as a priority existing chemical under the Australian National Industrial Chemicals Notification and Assessment Scheme. A total of 68 (11 personal and 57 area) air samples were collected, in accordance with the Australian standard membrane filter method. Fiber concentrations were determined by the traditional phase contrast microscopy (PCM) method and 16 selected samples were analyzed by the more powerful transmission electron microscopy (TEM). Chrysotile exposure of car mechanics measured by PCM was typically below the reportable detection limit of 0.05 f/mL, irrespective of whether disc brake, drum brake, or clutch was being serviced. These low levels can be attributed to the wet cleaning or aerosol spray methods used in recent years to replace the traditional compressed air jet cleaning. In the three brake shoe relining workshops, task-specific exposure reached up to 0.16 f/mL in the processes of cutting and radius grinding. TEM results were generally higher, due to its higher resolution power. The median diameter on samples taken from the service garages (passenger cars), as determined by TEM, was 0.5-1.0 micron; and was between 0.2-0.5 micron for the brake bonding and gasket processing workshops, while that for the bus service depot was 0.1-0.2 micron. Most of the respirable fibers (84%, mainly forsterite) from the bus service depot were below 0.2 micron in diameter which is the resolution limit of PCM. In the brake bonding and gasket cutting workshops, 34 percent and 44 percent of the chrysotile fibers were below 0.2 micron in diameter.

Erythrocyte cation fluxes during the menstrual cycle in normal female subjects.

1. Studies of erythrocyte cation transport mechanisms in vitro were performed on eight normotensive, premenopausal female subjects at the mid-points of the follicular and luteal phases of their menstrual cycles. Concurrent plasma concentrations of 17 beta-oestradiol, progesterone, aldosterone and renin activity were measured. 2. Ouabain-resistant, frusemide-resistant rubidium influx (an index of passive potassium diffusion) was significantly lower in the luteal than the follicular phase. 3. In further studies in four of the eight subjects, the mean rate constant of the rubidium influx measurement was also lower in the luteal than in the follicular phase. 4. There were no changes in Na+-K+ co-transport, sodium pump activity or intracellular cation concentrations throughout the cycle. 5. There was a tenfold fall in the mean plasma 17 beta-oestradiol/progesterone ratio, as well as increases in plasma aldosterone concentration and renin activity between the mid-follicular and mid-luteal phases. 6. We conclude that changes in plasma oestrogen/progesterone ratio during the menstrual cycle may be associated with alterations in passive potassium diffusion.

Erythrocyte cation fluxes in the normotensive and hypertensive clients of a health screening clinic.

Erythrocyte cation transport was measured in vitro using 22Na+ and 86Rb+ uptake techniques in Caucasian men with newly-detected hypertension and in male control groups. The Na+, K+ cotransport [determined by ouabain-resistant frusemide-sensitive (ORFS) components of Na+ or Rb+ influx], sodium pump activity (determined by ouabain-sensitive Rb+ influx) and erythrocyte Na+ and K+ concentrations were not significantly altered in hypertensive men. The total Na+ influx in hypertensives (n = 59) was significantly greater (P less than 0.001) than in controls. The difference was mainly attributable to an increase in the ouabain-resistant frusemide-resistant component of this flux. The total Rb+ influx in hypertensives (n = 39) was also greater (P less than 0.005) than in controls. Overall, both total Na+ influx and total Rb+ influx were positively correlated (P less than 0.01) with diastolic blood pressure and with habitual dietary intake of alcohol. Multivariate analyses after controlling for the effect of blood pressure showed that mean corpuscular volume (MCV) and alcohol intake were statistically significant predictor variables for total Rb+ influx, although not for total Na+ influx. The results are compatible with increased diffusion of cations across the erythrocyte membrane in hypertension, but raise the question of a possible role of alcohol intake in mediating this effect.

Measurement of circulating sodium-pump inhibitory activity in uraemia and essential hypertension.

By measuring in vitro the effect of deproteinized plasma on canine kidney Na+K+-ATPase activity, evidence was sought for the presence of a circulating inhibitor of the enzyme in 31 patients with end-stage renal failure, 10 patients treated with digoxin, and 22 patients with untreated essential hypertension. In the renal failure group, mean Na+K+-ATPase activity with plasma samples taken just before a regular haemodialysis was 88% of that obtained with plasma from a normotensive control group (P less than 0.001). In digoxin-treated patients, the result was 94% of that obtained in control subjects (P less than 0.005). There was no significant difference in mean Na+K+-ATPase activity with plasma, between the hypertensive and control groups, or between age- and sex-matched subsets of these groups. The hypertensive group did not differ significantly from the control group in plasma renin activity or erythrocyte Na+ concentration. It was concluded that a circulating digitalis-like sodium-pump inhibitor was readily detectable in volume-expanded renal failure, but not in normal-renin essential hypertension.

Estrogen and progesterone receptors in human ovarian tumors.

Estrogen and progesterone receptors were measured in cystosols prepared from 32 normal ovaries and 25 benign and 49 malignant ovarian tumors. In normal ovarian tissue, estrogen and progesterone receptors were detected in 22 and 75% of specimens, respectively. Estrogen receptors were present in low concentrations ranging from 2 to 9 fmol/mg cytosol protein. The estrogen receptor content and distribution were similar in benign tumors (20%), but progesterone receptors were significantly decreased in 16% of specimens (P less than 0.001). In malignant ovarian tissues, estrogen receptors were present in 57% of specimens in concentration ranging from 1 to 132 fmol/mg cytosol protein. Of these, 72% of tissues had estrogen-receptor concentrations greater than 10 fmol/mg cytosol protein. The presence of estrogen receptors in ovarian cancer was significantly different from normal ovaries and benign tumor tissues (P less than 0.01). Progesterone receptors were detectable in 29% of ovarian cancer specimens. Estrogen and progesterone receptors were present alone or in combination, in 65% of ovarian cancers. The similarity in sex steroid content between ovarian and breast cancer warrants prospective studies of sex steroid receptor content in ovarian malignancies as a possible predictive index of survival and response to hormone therapy.

Preservation of reproductive potential in diethylstilbestrol-related vaginal adenocarcinoma.

PIP: One consequence of vaginal adenocarcinoma in adolescents is the loss of reproductive potential. This report describes total removal of the vagina and of the vaginal portion of the cervix with an attached strip of bladder wall, together with bilateral extraperitoneal pelvic lymph adenectomy which allows preservation of reproductive potential. The woman, age 23, had had intrauterine exposure to stilbestrol and ethisterone. 2 factors affect the management of such cases: 1) removal of the primary tumor must be geographically clear in 3 dimensions, and 2) the incidence of pelvic lymph node metastasis is greater than that of comparable squamous cell lesions, indicating a need for lymphadenectomy. In this case menstruation was suppressed by medroxyprogesterone injection. Follow-up for a number of years is needed.^ieng

Latitudinal variation in octanol dehydrogenase and acid phosphatase allele frequencies in Drosophila melanogaster.

The octanol dehydrogenase (Odh) and acid phosphatase (Acph) loci of Drosophila melanogaster are each polymorphic for two electrophoretically detectable alleles. The frequencies of the Odh and Acph alleles have been analysed in populations sampled from up to a 40 ° latitudinal range in each of Australasia, North America and Europe/Asia. Odh (S) frequency is found to be significantly negatively associated with distance from the equator in all three zones. The relationship of Acph (S) frequency to distance from the equator is significant and negative in Australasia but neither significant nor consistent in sign in North America and Europe/Asia.

The effect of storage time and molybdate on steroid receptors in gynaecological tissues.

Human female reproductive tract tissues were analysed for estrogen and progestogen receptor content in the presence or absence of sodium molybdate immediately after removal at surgery. Other fractions of the tissue were stored in liquid nitrogen and similarly analysed after 2, 4, 6 and 8 weeks storage. The results showed that at all times the apparent receptor content for both steroids was significantly higher (P less than 0.001) and Kd values were significantly lower (P less than 0.02) in assays carried out with 10 mM molybdate added to the buffer systems. Furthermore, as soon as either whole tissue or tissue cytosol was frozen for storage, receptors were "lost" with values decreasing by approximately 30% for both steroid receptors. However, once frozen in liquid nitrogen tissue receptor content remained stable over the eight weeks of study. It is recommended that laboratories standardize techniques to allow valid comparisons of results.

Latitudinal relationships of esterase-6 and phosphoglucomutase gene frequencies in Drosophila melanogaster.

Geographic variation in Esterase-6 (Est-6) and Phosphoglucomutase (Pgm) gene frequencies in Australasian populations of Drosophila melanogaster are compared with analogous data collated from 16 previous reports for North America and Europe/Asia. A large-scale latitudinal cline is found on all three zoogeographic zones for Est-6 and overall, Est-61.00 frequency increases from about 20 per cent around 20 degrees latitude to about 80 per cent approaching 50 degrees latitude. In contrast, there is no consistent evidence for the latitudinal cline in Pgm gene frequencies in any of the three zones with Pgm1.00 frequency generally about 85 per cent and Pgm1.20 and Pgm0.70 frequencies each between 5 per cent and 10 per cent. The consistent Est-6 clines are attributed to latitudinal selection gradients but not consistent correlations are found between Est-6 gene frequencies and maximum or minimum temperature or rainfall which might be associated with these gradients. The directions of the Est-6 clines in fact run counter to expectations based on the in vitro thermostabilities of the respective allozymes.

Restriction endonuclease and molecular analyses of three rat genomes with special reference to chromosome rearrangement and speciation problems.

When differences are found between related species of organisms, it is often assumed that the differences themselves are causal factors either in speciation itself or in processes related to speciation. Two recent proposals on the functions of satellite DNA (Hatch et al., 1976 and Fry and Salser 1977) are that (a) large amounts of satellite DNA are important in facilitating chromosome rearrangements and hence cytogenetic evolution, and (b) satellite DNA differences between homologous chromosomes lead to pairing difficulties and are important in generating infertility barriers and hence speciation. If these proposals were to have some generality, one could expect organisms with very low amounts of highly repeated DNA to exhibit few chromosome rearrangements and to be evolutionarily conservative in a cytogenetic sense.--We have chosen two very closely related species of rat which are phenotypically almost indistinguishable and which have undergone massive genome reorganization. They differ by 11 major centric rearrangements (2n = 32, 2n = 50). We have characterised their genomes by restriction endonuclease digestions, thermal denaturations, analytical ultracentrifugations and reassociation techniques, and have found that they have virtually no highly repeated DNA. Thus the 11 major chromosomal rearrangements have been fixed in present day genomes with hardly any highly repeated DNA, centric or otherwise.--It appears therefore, that a large amount of highly repeated DNA is not obligatory for the formation and fixation of chromosome rearrangements. In addition, the existing literature reveals that one can find almost any situation at all, from species groups with high amounts of satellite DNA and no gross chromosomal rearrangements, to ones such as those described here, with tiny amounts of highly repeated DNA and massive chromosomal reorganisation. Since direct experimental data indicates that satellite DNA differences per se between homologous chromosomes do not cause infertility, speculations concerning modes of speciation based on satellite DNA differences between otherwise homologous chromosomes would appear to be ill founded.