Evaluation of the exposure, dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 1: Experimental design, aerosol exposure, lung burdens and BAL.

This 90-day repeated-dose inhalation toxicology study of brake-dust (BD) (brakes manufactured with chrysotile) in rats provides a comprehensive understanding of the biokinetics and potential toxicology in the lung and pleura. Exposure was 6 h/d, 5d/wk., 13wks followed by lifetime observation (~20 % survival). Control groups included a particle control (TiO2), chrysotile, commercial crocidolite and amosite asbestos. Aerosol fiber distributions of the chrysotile, crocidolite and amosite were similar (fibers L > 20 µm/cm3: chrysotile-Low/High 29/72; crocidolite 24; amosite 47 fibers/cm3; WHO-fibers/cm3: chrysotile-Low/High 119/233; crocidolite 181; amosite 281 fibers/cm3). The number of particles/cm3 in the BD was similar to that in the chrysotile, crocidolite & amosite exposures (BD 470-715; chrysotile 495-614; crocidolite 415; amosite 417 particles/cm3). In the BD groups, few fibers L > 20 µm were observed in the lungs at the end of exposure and no fibers L > 20 µm at 90d post exposure. In the chrysotile groups, means of 204,000 and 290,000 fibers(L > 20 µm)/lung were measured at 89d. By 180d, means of 1 and 3.9 fibers were counted on the filter corresponding to 14,000 and 55,000 fibers(L > 20 µm)/lung. In the crocidolite and amosite groups mean lung concentrations were 9,055,000 and 11,645,000 fibers(L > 20 µm)/lung at 89d. At 180d the means remained similar with 8,026,000 and 11,591,000 fibers(L > 20 µm)/lung representing 10-13% of the total lung fibers. BAL determined the total number of macrophages, lymphocytes, neutrophils, eosinophils, epithelial-cells and IL-1 beta, TNF-alpha and TGF-beta. At the moderate aerosol concentrations used in this study, neutrophil counts increased ~5 fold in the amphibole asbestos exposure groups. All other groups and parameters showed no important differences at these exposure concentrations. The exposure and lung burden results provide a sound basis for assessing the potential toxicity of the brake dust in comparison to the TiO2 particle control and the chrysotile, crocidolite and amosite asbestos control groups. The BAL results provide an initial indication of the differential response. Part 2 presents the presentation and discussion of the histopathological and confocal microscopy findings in this study through 90 days post exposure.

Evaluation of the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos in a 90-day quantitative inhalation toxicology study - Interim results Part 2: Histopathological examination, Confocal microscopy and collagen quantification of the lung and pleural cavity.

The interim results from this 90-day multi-dose, inhalation toxicology study with life-time post-exposure observation has shown an important fundamental difference in persistence and pathological response in the lung between brake dust derived from brake-pads manufactured with chrysotile, TiO2 or chrysotile alone in comparison to the amphiboles, crocidolite and amosite asbestos. In the brake dust exposure groups no significant pathological response was observed at any time. Slight macrophage accumulation of particles was noted. Wagner-scores, were from 1 to 2 (1 = air-control group) and were similar to the TiO2 group. Chrysotile being biodegradable, shows a weakening of its matrix and breaking into short fibers & particles that can be cleared by alveolar macrophages and continued dissolution. In the chrysotile exposure groups, particle laden macrophage accumulation was noted leading to a slight interstitial inflammatory response (Wagner-score 1-3). There was no peribronchiolar inflammation and occasional very slight interstitial fibrosis. The histopathology and the confocal analyses clearly differentiate the pathological response from amphibole asbestos, crocidolite and amosite, compared to that from the brake dust and chrysotile. Both crocidolite and amosite induced persistent inflammation, microgranulomas, and fibrosis (Wagner-scores 4), which persisted through the post exposure period. The confocal microscopy of the lung and snap-frozen chestwalls quantified the extensive inflammatory response and collagen development in the lung and on the visceral and parietal surfaces. The interim results reported here, provide a clear basis for differentiating the effects from brake dust exposure from those following amphibole asbestos exposure. The subsequent results through life-time post-exposure will follow.

Evaluation of the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to chrysotile or crocidolite asbestos in a 28-day quantitative inhalation toxicology study.

This study provides an understanding of the biokinetics and potential toxicology in the lung and pleura following inhalation of brake-dust (brakes manufactured with chrysotile). The design included a 28-day repeated multi-dose inhalation exposure (6 h/d, 5 d/wk, 4 wks) followed by 28-days without exposure. Fiber control groups included a similar grade chrysotile as used in the brakes and a commercial crocidolite asbestos. Aerosol fiber distributions of the chrysotile and crocidolite were similar (fiber-length > 20 µm/cm3: Chrysotile-low/high 42/62; Crocidolite-low/high 36/55; WHO-fibers/cm3: Chrysotile-low/high 192/219; Crocidolite-low/high 211/255). The total number of aerosol particles/cm3 in the brake-dust was similar to that in the chrysotile (Brake-dust 710-1065; Chrysotile 532-1442). Brake-dust at particle exposure levels equal to or greater than chrysotile or crocidolite caused no indication of microgranulomas, epithelial hyperplasia, or fibrosis (Wagner score < 1.7) or changes in bronchoalveolar lavage (BAL) indices from the air control. Chrysotile BAL indices did not differ from the air control. Pathologically, there was low level of inflammation and epithelial hyperplasia, but no fibrosis (Wagner score ≤ 3). Crocidolite induced elevated neutrophils and cell damage (BAL), persistent inflammation, microgranulomas, and fibrosis (Wagner scores 4) which persisted through the post exposure period. Confocal microscopy of snap-frozen chestwalls showed no difference between control, brake-dust and chrysotile-HD groups or in thickness of visceral or parietal pleural. The crocidolite exposure resulted in extensive inflammatory response, collagen development and adhesions between the visceral and parietal surfaces with double the surface thickness. These results provide essential information for the design of a subsequent subchronic study.

Evaluation of the fate and pathological response in the lung and pleura of brake dust alone and in combination with added chrysotile compared to crocidolite asbestos following short-term inhalation exposure.

This study was designed to provide an understanding of the biokinetics and potential toxicology in the lung and pleura following inhalation of brake dust following short term exposure in rats. The deposition, translocation and pathological response of brake-dust derived from brake pads manufactured with chrysotile were evaluated in comparison to the amphibole, crocidolite asbestos. Rats were exposed by inhalation 6h/day for 5 days to either brake-dust obtained by sanding of brake-drums manufactured with chrysotile, a mixture of chrysotile and the brake-dust or crocidolite asbestos. The chrysotile fibers were relatively biosoluble whereas the crocidolite asbestos fibers persisted through the life-time of the animal. This was reflected in the lung and the pleura where no significant pathological response was observed at any time point in the brake dust or chrysotile/brake dust exposure groups through 365 days post exposure. In contrast, crocidolite asbestos produced a rapid inflammatory response in the lung parenchyma and the pleura, inducing a significant increase in fibrotic response in both of these compartments. Crocidolite fibers were observed embedded in the diaphragm with activated mesothelial cells immediately after cessation of exposure. While no chrysotile fibers were found in the mediastinal lymph nodes, crocidolite fibers of up to 35 µm were observed. These results provide support that brake-dust derived from chrysotile containing brake drums would not initiate a pathological response in the lung or the pleural cavity following short term inhalation.

Trends in mesothelioma mortality rates in South Africa: 1995-2007.

OBJECTIVE: In 1984, South Africa had one of the highest mesothelioma rates in the world. The objective of this analysis was to calculate mesothelioma mortality rates in the South African population from 1995 to 2007. METHODS: Annual mortality data and midyear population estimates were used to compute mortality rates by age group and gender for each year. The WHO World Standard Population was used as the reference population to calculate age-adjusted rates. Poisson regression models were used to test for trends. RESULTS: In total, 2509 deaths due to mesothelioma were identified in the study period: 1920 in men and 588 in women. There were no significant trends in mesothelioma mortality rates: age-adjusted mortality rates fluctuated from 11 to 16 and from 3 to 5 per million per year for men and women, respectively. CONCLUSION: These mortality rates are much lower than expected, given the historical production and use of, and high exposure to, asbestos in South Africa. Possible reasons for this are discussed, including the effect of HIV which has been instrumental in reducing the life expectancy of South Africans in the last two decades. Asbestos-exposed individuals may not live long enough to develop mesothelioma. Competing causes of death need to be taken into account when constructing models to predict mesothelioma mortality rates.

Chlamydia pneumoniae in atheroma: consideration of criteria for causality.

AIMS: (1) To seek evidence of the existence of Chlamydia pneumoniae in a spectrum of atheromatous lesions in different types of arteries from individuals of different ages, using a polymerase chain reaction (PCR) assay supported by electron microscopy and immunocytochemistry; (2) to use electron microscopy to examine interactions between C pneumoniae and the cells present in the arterial tissue; (3) to assess the extent to which the data fulfil the criteria for causality. METHODS: At necropsy examination, 35 arterial specimens were taken from 25 subjects. The grade of atheroma was determined macroscopically and microscopically and the tissues coded and examined by the three techniques. RESULTS: Of the 35 specimens, 24 had macroscopic or microscopic atheromatous lesions of varying degree. Twenty two of the 35 specimens were examined by electron microscopy, C pneumoniae-like bodies being found in 11 (50%); seven specimens were examined by the immunocytochemical method, positive staining being detected in three; and all specimens were examined by the PCR technique, 15 (43%) being PCR positive. Overall, of the 24 specimens with lesions, 17 (71%) were positive by at least one of the three tests, whereas of the 11 specimens without lesions, only one was positive. The positive specimens comprised 10 of 19 aortas, three of six iliac arteries, and one coronary and one pulmonary artery. C pneumoniae was detected in four of six specimens in which there were early changes and in a 20 year old subject. Concerning the 25 subjects, of 17 who had atheromatous arteries, 14 (82%) were C pneumoniae positive and of the eight who had normal arteries, none was positive. CONCLUSIONS: There is a strong correlation between C pneumoniae and arterial atheromatous lesions. The organism may contribute to the disease process by damaging smooth muscle cells.

Intracerebral malignant fibrous histiocytoma: a light and electron microscopic study with immunohistochemistry.

A 65-year-old man presented with a tumor within the right cerebral hemisphere. Biopsy showed a pleomorphic neoplasm which was diagnosed as a malignant fibrous histiocytoma only after immunohistochemical and electron microscopic examination. Full clinical and radiological investigation, including total body CAT scanning, failed to reveal any other deposits, and thus it is believed to have arisen in the brain. It is emphasised that this diagnosis could not have been reached had only conventional histological techniques been available.

Primary hyperaldosteronism due to a functional black (pigmented) adenoma of the adrenal cortex.

The clinical and pathologic findings are reported in a case of primary hyperaldosteronism due to a functional black (pigmented) adenoma of the adrenal cortex. Cortical atrophy of the involved gland was present, the mechanism of which was obscure.

Fine needle aspiration of pediatric abdominal masses. Cytologic and electron microscopic diagnosis.

Fine needle aspiration (FNA) was performed under ultrasound guidance on 17 abdominal masses in 16 pediatric patients at Baragwanath Hospital. The aspirated cellular material was assessed by conventional cytomorphology and by electron microscopy (EM). A diagnosis of malignancy was rendered for all 15 tumors that were adequately sampled (88.2%); the remaining 2 masses yielded insufficient material for either light microscopy or EM. Cytologic cell typing (including the use of EM) was successful in 12 of the 15 tumors (80%) as compared with the histologic diagnosis. EM was in agreement with the initial cytologic diagnosis in eight tumors, but corrected the initial impression in four tumors. The tumors with adequate aspirates included nine nephroblastomas and single examples of neuroblastoma, hepatoblastoma, non-Hodgkin's lymphoma, rhabdomyosarcoma, renal carcinoma and malignant rhabdoid tumor. The last three were not accurately typed by cytology plus EM. These preliminary results suggest that FNA cytology with adjunctive EM could become a useful technique in the preoperative assessment of pediatric abdominal tumors.

Small cell undifferentiated carcinoma of the parotid gland. Cytologic, histologic, immunohistochemical and ultrastructural features of a neuroendocrine variant.

A case of primary small cell undifferentiated carcinoma (SCUC) of the parotid gland, diagnosed initially by fine needle aspiration (FNA) cytology and confirmed by histology, immunohistochemistry and transmission electron microscopy (TEM), is presented. The FNA cytologic features that enabled an accurate diagnosis of this rare salivary gland tumor included nuclear granularity and markedly angular nuclear molding of numerous small cells that were usually present as large syncytia in an inflammatory background. Numerous mitotic figures were also present in this vascular lesion. These features were also evident in the surgical specimens. Immunohistochemistry demonstrated neuron-specific enolase positivity while TEM demonstrated intracytoplasmic neurosecretory granules in this case, indicating a neuroendocrine derivation for this neoplasm instead of the more usual origin of salivary gland SCUCs in ductal epithelial or myoepithelial tissue.

The pulvillus and empodium in Culex quinquefasciatus: visualization with the light microscope and a study of fine structure with the scanning electron microscope.

The empodia and pulvilli on each postarsus were examined in male and female Culex quinquefasciatus. Up to 160x magnification was required to see them clearly under the stereo light microscope but they were more readily visible under the compound light microscope as slide mounts at 100-200x magnification. Scanning electron micrographs of female and male pulvilli showed that they are either well developed (females) or inconspicuous (males) and that they consist of setal tufts composed of both pointed and trumpet-ended setae. The ultrastructure of the pulvilli is described and their possible function in oviposition is discussed.

A South African database of samples analysed for the presence of asbestos

Background: Asbestos mining and other activities have left a legacy of environmental contamination. Asbestos was used in a large number of manufactured products but little is documented about the nature and location of these products. Compliance with asbestos regulations depends on accurate identification of the presence of asbestos. The National Institute for Occupational Health (NIOH) has been identifying asbestos for regulatory purposes since 2003. Objective: To analyse a database of samples submitted for asbestos analysis to the NIOH. Methods: Asbestos was identified using scanning electron microscopy and energy dispersive spectroscopy. The data were analysed using STATISTICA version 11. Results: From 2003 to 2012; 1514 samples were analysed. Asbestos was identified in 59.9 of the bulk samples and crocidolite was present in 45.4 of these. Information about samples containing asbestos; including their origin and associated activities; are described. Conclusions: Although asbestos is no longer mined or used in South Africa; workers remain at risk of exposure due to asbestos-containing materials which persist in the environment. Knowledge of these materials gained from routinely collected data may assist in the safe removal of asbestos and prevent further adverse health =effects

Rock drills used in South African mines: a comparative study of noise and vibration levels.

OBJECTIVES: To compare the noise and vibration levels associated with three hand-held rock drills (pneumatic, hydraulic and electric) currently used in South African mines, and a prototype acoustically shielded self-propelled rock drill. METHODS: Equivalent A-weighted sound pressure levels were recorded on a geometrical grid, using Rion NL-11 and NL-14 sound level meters. Vibration measurements were conducted on the pneumatic, hydraulic and electric drills in accordance with the ISO5349-1 (2001) international standard on human exposure to hand-transmitted vibration, using a Brupsilonel and Kjaer UA0894 hand adaptor. PCB Piezo accelerometers were used to measure vibration in three orthogonal directions. No vibration measurements were conducted on the self-propelled drill. RESULTS: All four drills emitted noise exceeding 85 dB(A). The pneumatic drill reached levels of up to 114 dB(A), while the shielded self-propelled drill almost complied with the 85 dB(A) 8 h exposure limit. Vibration levels of up to 31 m s(-2) were recorded. These levels greatly exceed recommended and legislated levels. CONCLUSIONS: Significant engineering advances will need to be made in the manufacture of rock drills to impact on noise induced hearing loss and hand arm vibration syndrome. Isolating the operator from the drill, as for the self-propelled drill, addresses the problems of both vibration and noise exposure, and is a possible direction for future development.

Lack of cilia and squamous metaplasia in upper respiratory tract biopsies from children.

Biopsies were obtained from 47 children with upper respiratory tract infection aged 30 days - 12 years. All had been extensively investigated and no underlying cause for their symptoms could be found. A total of 63 specimens (46 from the inferior nasal turbinate, 8 from the trachea and 9 from the carina or bronchus) were examined. Only 4 showed no degree of squamous metaplasia and 8 showed significant numbers of acquired-type morphological abnormalities of the cilia. Twenty-six of the 63 biopsies had significantly reduced numbers of cilia and 34 had no cilia. Inherited-type changes were seen in only 1 patient. The net result of a lack of cilia and the immotile-cilia syndrome is the same--absence of mucociliary transport.

Inflammatory plasma cell infiltration of the urinary bladder in the aging C57BL/Icrfa(t) mouse.

An age related increased cellularity in the lamina propria of the mouse bladder is described. The identified cell types involved are plasma cells, lymphocytes, and eosinophilic leukocytes, and probably represent an inflammatory plasma cell infiltration. Two rare unidentified cell types were also seen. The cause of the inflammatory reaction is unknown, but the failure to detect a causative microorganism suggests that it might be an autoimmune response, possibly related to the clinical condition of interstitial cystitis. From foci of increased cellularity, located in the close proximity of blood vessels, lymphocytes migrate to the urothelium which otherwise shows no ultrastructural changes with age.

Kaposi's sarcoma in different populations in South Africa.

Patients with Kaposi's sarcoma (13 black and 5 white heterosexuals and 2 homosexuals with the acquired immunodeficiency syndrome (AIDS)) were investigated clinically, histologically, serologically and immunologically. Clinically, lymph node involvement was present in 9 of the 13 black heterosexuals, but was not seen in the other two groups. Oedema, which was seen in 13 of the 14 black patients, was only present in 1 white patient. The lesions were of the nodular cutaneous type except in the AIDS patients who presented with plaque-like lesions. Whereas all non-AIDS patients were negative for HTLV-III antibodies, both AIDS patients were positive and showed a marked cell-mediated immune (CMI) deficiency. Only 1 heterosexual white and 4 heterosexual black patients had some degree of CMI deficiency. South Africans with Kaposi's sarcoma do not have significant underlying immunodeficiency or associated opportunistic infections. No serological or electron microscopic evidence was found to support the aetiological role of cytomegalovirus in Kaposi's sarcoma. The findings suggest that the cell of origin of this tumour is the vascular endothelial cell.

Histological and ultrastructural findings suggesting an initiating role for Chlamydia pneumoniae in the pathogenesis of atherosclerosis.

AIMS: An association between Chlamydia pneumoniae and atherosclerosis is now well established. The finding of C. pneumoniae in atherosclerotic lesions has led to the hypothesis that this organism may have an aetiological role in atherogenesis. The implications of such a concept are enormous, but to date the pathological features of the lesion have not been examined in the light of this new hypothesis. This study was designed to determine the pathological basis of the association between C.pneumoniae and atherosclerotic lesions. METHODS: The pathological features of 50 atherosclerotic lesions from 50 different patients, in which C.pneumoniae had been demonstrated by immunocytochemistry and PCR techniques, were examined using light and electron microscopy techniques. In 20 cases the lesions were fatty streaks, 20 were fibro-atheroma lesions, and 10 were advanced, complicated lesions. RESULTS: Intimal smooth-muscle cells infected with C. pneumoniae exhibit vacuolation, loss of myofilaments, an increase in lipid, rupture and fragmentation. Macrophages phagocytose these muscle cell fragments, lipid and C. pneumoniae. Large numbers of extracellular C. pneumoniae organisms were identified in the central necrotic core, in areas of fibrosis, in areas of fragmentation of the internal elastic lamina, and in ceroid bodies. Neither pathological changes nor organisms were seen in the endothelium. CONCLUSIONS : C. pneumoniae infection of intimal smooth&hypen; muscle cells is accompanied by cytoplasmic alterations and damage. The fatty streak appears to be formed by a macrophage response to this muscle damage. C. pneumoniae is found in early, mature and advanced lesions. This is the first study of the pathology of atherosclerosis suggesting that the lesion be interpreted as an infective chlamydial granuloma.

Association between Chlamydia pneumoniae and atherosclerotic lesions.

There can no longer be any doubt that viable Chlamydia pneumoniae organisms are present in atherosclerotic lesions. Indeed, the endovascular presence of C. pneumoniae in coronary artery disease (CAD) is common. The fact that this lesion, which is the major cause of stroke, coronary heart disease ( CHD), peripheral vascular disease and aortic aneurysm, can no longer be regarded as sterile has prompted a good deal of study and speculation. Atherosclerotic lesions have been studied in detail, but until recently histological descriptions of the lesion have not included C. pneumoniae organisms. Reviews and analysis of the literature confirm the association between C. pneumoniae and atherosclerotic lesions and CHD. The possibility that C. pneumoniae plays a causal or contributory role in the development of atherosclerotic lesions has been debated. It is of major importance as there is already evidence that antibiotic therapy may be of clinical benefit in patients with CHD. Large clinical trials using antichlamydial agents have been embarked upon which may provide further evidence of a causal role for C. pneumoniae. The underlying mechanism of how C. pneumoniae contributes to lesions and the effect of antibiotic therapy on lesions remain unknown. The association between C. pneumoniae and atherosclerosis is reviewed. Particular attention is paid to the lesion itself and the presence of C. pneumoniae. Potential areas of study that may contribute to this rapidly expanding area of research is explored.

A comparative morphometric analysis of the component tissues of the urethra in young and old female C57BL/ICRFAt mice.

Histologic preparations of the urethras of 3 and 30-month-old virgin female C57 mice were stereologically analyzed with a light microscope with an eyepiece grid. Serial sections of entire urethras were stained and divided into ten representative regions; the component tissues of each region were analyzed. There was no significant change with age in the total muscle component in each region. The muscle, however, was divided into two types: muscle with and muscle without the infiltration of collagen fibers. The amount of muscle with collagen infiltration was significantly increased in some regions of the urethra in the 30-month-old group. There was no age-associated significant difference in the vascular or connective tissue components of the urethra. A difference in the glandular component was recorded in one region only, because of change in the ducts of the clitoral glands. We noted differences in the lumen and its epithelium that were attributable to the more open urethral lumen in the young group in certain regions.