Characterisation of respiratory health and exposures at a sintered permanent magnet manufacturer.

Sintered permanent magnets are made from the powdered metals of cobalt, nickel, aluminium, and various rare earths. During production, exposure to respirable crystalline silica and asbestos may also occur. Reported here is a cross sectional study of 310 current and 52 retired hourly employees who worked 10 or more years making sintered magnets.

Fibroblasts of rabbit kidney in culture. I. Characterization and identification of cell-specific markers.

There is currently no information available as to whether different renal fibroblast subpopulation can be identified and whether they show differences in functional properties. We therefore compared the growth characteristics of interstitial fibroblasts derived from the rabbit renal cortex and inner medulla (papilla) and sought cell-specific markers for the two populations of cells. Analyses of the population dynamics revealed that the mitotic lifespan of papillary fibroblasts (PF) is approximately 50% longer than that of cortical fibroblasts (CF), with the former going through 20 cumulative population doublings (CPD) before transition into terminally differentiated postmitotic cells compared with 9 CPD in CF.

Fibroblasts of rabbit kidney in culture. II. Paracrine stimulation of papillary fibroblasts by PDGF.

To examine the role of tubulointerstitial cell interaction in the regulation of fibroblast growth, fibroblasts from the rabbit renal cortex (CF) and papilla (PF) were cocultured with epithelial cells from the same tissue location. Inner medullary collecting duct epithelial cells (IMCDE) or IMCDE-conditioned medium stimulated DNA synthesis in PF, whereas proximal tubule epithelium (PTE) had no effect on the proliferation of CF. PF and CF showed a similar mitogenic response to exogenous epidermal growth factor and insulin-like growth factor 1 (IGF-I).

Primary response gene expression in renal hypertrophy and hyperplasia: evidence for different growth initiation processes.

Unilateral nephrectomy is followed by compensatory renal hypertrophy, a response in which the cells of the contralateral kidney increase in size and protein content without synthesizing DNA or dividing. To determine whether the earliest phase of the hypertrophic response has features similar to mitogenic or differentiation responses, we have characterized the expression of several primary-response genes, the 12-O-tetradecanoylphorbol-13-acetate (TPA)-inducible sequences (TIS) genes, which are rapidly and transiently induced in the absence of intervening protein synthesis, in a variety of mitogenic and differentiation cell systems. TIS gene induction was studied in the contralateral kidney of uninephrectomized and sham-operated mice, as well as in the kidneys of mice in which renal cell proliferation was induced by folic acid injection.

Integration of new embryonic nephrons into the kidney.

The current report summarizes our experiments exploring the feasibility of creating a chimeric kidney, that is, an organ constituted by cells derived from more than one fertilized ovum. The overall strategy has been to obtain donor renal tissue from avian and murine embryos and to implant this into the host avian mesonephric mesoderm or into the cortex of murine neonatal kidney. In both models, donor cells were distinguished from the host by the presence of characteristic nuclear or cytoplasmic markers.

Do glomerular hemodynamic adaptations influence the progression of human renal disease?

Although experiments in the rat suggest that glomerular hemodynamic alterations following a reduction of renal mass may be implicated in the progression of chronic renal failure, we argue that the deleterious effects of similar adaptations in human renal disease are unproven. In the otherwise normal solitary kidney the supranormal glomerular filtration rate (GFR) remains stable over the longterm, and in early diabetic nephropathy which is also accompanied by hyperfiltration, renal deterioration cannot be dissociated from a rise in systemic blood pressure. In patients with miscellaneous renal diseases and a depressed basal GFR there is indirect evidence that hyperfiltration might occur in some of the remnant glomeruli.

Creation of a functioning chimeric mammalian kidney.

The possibility of adding new nephrons to the mammalian kidney was studied. Embryonic metanephric tissue was implanted into the renal cortex of neonatal mice less than 24 hours old, and the development of the chimeric kidney was followed over the following two to four weeks. Donor tissue was obtained from the homozygous beige mouse and a mouse line transgenic for the beta-globin gene, which provided distinct cellular and nuclear markers which were used to distinguish donor from recipient nephrons.

Hypertrophy of renal mitochondria.

Compensatory renal hypertrophy leads to an increase in the size and metabolic capacity of renal tubular cells. Increased transport and metabolic activities must be sustained by an augmented rate of energy production, which is largely dependent on mitochondrial processes. Although previous studies have suggested that mitochondria proliferate in the hypertrophying cell, the data to support this have not been convincing.

National estimates of occupational exposure to animal bladder tumorigens.

A prevention program for occupational bladder cancer should be based on an estimate of the number of workers previously and currently exposed to bladder carcinogens. The National Occupational Exposure Survey (NOES), which identified potential occupational exposures in approximately 5000 private sector firms in 1981 to 1983, is the best available source for recent hazard estimates; the National Occupational Hazard Survey (NOHS), conducted in 1972 and 1974, for past exposure estimates. The National Institute for Occupational Safety and Health Registry of Toxic Effects of Chemical Substances (RTECS) identified nearly 200 substances associated with animal bladder tumors.

Guidelines for medical screening in the workplace.

This chapter deals with general principles of conducting medical examinations to detect adverse health effects of workplace exposures and thereby prevent occupational disease or slow its progression. Much of the discussion is most relevant to screening for effects of chemical hazards, but many of the principles presented apply to physical and biological hazards as well. Procedural and administrative aspects of workplace medical examinations that are not "exposure specific" and are applicable to all medical programs are reviewed.

Renal hypertrophy, growth factors, and nephropathy in diabetes mellitus.

In early type 1 diabetes mellitus, hypertrophy of the kidney is a consistent finding. It is easily diagnosed using current noninvasive methods, especially ultrasonography. Renal functional changes occur in association with hypertrophy, most notably glomerular hyperfiltration.

Epidermal growth factor accelerates functional recovery from ischaemic acute tubular necrosis in the rat: role of the epidermal growth factor receptor.

1. Severe, ischaemic, acute tubular necrosis was induced in rats by bilateral occlusion of the renal arteries. The experimental group received exogenous epidermal growth factor infused directly into the renal arterial circulation.

Occupational health in the 1990s.

Where have we come since the Occupational Safety and Health Act was passed in 1970? Have we made progress in this country toward "safe and healthful working conditions for working men and women?" Many hazardous exposures that were prevalent before the creation of NIOSH, OSHA, and MSHA have been reduced. Exposure to asbestos, coal dust, silica, lead, and cotton dust are common examples. Through OSHA's Hazard Communication Standard and state Right to Know laws as well as an increase in the dissemination of information, the average employer and worker today is better informed of specific hazards on the job, and more attentive to safety measures.

Molecular events in the organization of renal tubular epithelium: from nephrogenesis to regeneration.

Information from studies of embryonic nephrons and established renal tubular cell lines in culture can be integrated to derive a picture of how the renal tubule develops and regenerates after acute injury. During development, the formation of a morphologically polarized epithelium from committed nephric mesenchymal cells requires an external signal for mitogenesis and differentiation. Polypeptide growth factors, in some cases mediated through oncogene expression, act in an autocrine or paracrine fashion to stimulate the production of extracellular matrix proteins that probably provide the earliest orientation signal for the cell.