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PubMed1995

Respiratory health effects of man-made vitreous (mineral) fibres.

The group of man-made mineral or vitreous fibres (MMMFs or MMVFs) includes glass wool, rock wool, slag wool, glass filaments and microfibres, and refractory ceramic fibres (RCFs). Experimental observations have provided evidence that some types of MMVF are bioactive under certain conditions. The critical role of size parameters has been demonstrated in cellular and animal experiments, when intact fibres are in direct contact with the target cells. It is, however, difficult to extrapolate the results from these studies to humans since they bypass inhalation, deposition, clearance and translocation mechanisms. Inhalation studies are more realistic, but show differences between animal species regarding their sensibility to tumour induction by fibres. Fibre biopersistence is an important factor, as suggested by recent inhalation studies, which demonstrate positive results with RCF for fibrosis, lung tumours and mesothelioma. There is no firm evidence that exposure to glass-, rock- and slag wool is associated with lung fibrosis, pleural lesions, or nonspecific respiratory disease in humans. Exposure to RCF could enhance the effects of smoking in causing airways obstruction. An elevated standard mortality ratio for lung cancer has been demonstrated in cohorts of workers exposed to MMVF, especially in the early technological phase of mineral (rock slag) wool production. During that period, several carcinogenic agents (arsenic, asbestos, polycyclic aromatic hydrocarbons (PAH)) were also present at the workplace and quantitative data about smoking and fibre levels are lacking. It is not possible from these data to determine whether the risk of lung cancer is due to the MMVFs themselves. No increased risk of mesothelioma has been demonstrated in the cohorts of workers exposed to glass-, slag- or rock wool. There are in fact insufficient epidemiological data available concerning neoplastic diseases in RCF production workers because of the small size of the workforce and the relatively recent industrial production.

Air Pollutants, Occupational↗
PubMed2005

Simple compressive method for treatment of auricular haematoma using dental silicone material.

Most of the previous treatment methods for auricular haematoma are inconvenient for both patients and doctors because they are time-consuming and complex and must be performed under sterile conditions. The purpose of this study was to evaluate the effectiveness of a simple compressive method using a dental (silicone) impression material and comparing it with other methods for treatment of auricular haematomas. The authors aspirated a haematoma and then placed a mixed base and catalyst of silicone putty material on the anterior and posterior surfaces of the auricle in the shape of an inverted U for seven days. From the 24 cases managed with this method, 23 cases (95.8 per cent) were successfully healed. Eight patients were treated with a collodion-cotton wool cast and 16 of 19 patients were successfully treated with dental cotton-wool rolls. The average number of those visiting the hospital was 2.7 for the collodion-cotton wool cast, 6.9 for the dental cotton-wool roll, and 3.1 for dental silicone. The mean treatment durations were 8.1 days for the collodion-cotton wool cast, 13.8 days for the dental cotton-wool roll, and 8.6 days for dental silicone. The authors believe that this compressive method using dental silicone material is simple and appropriate for the treatment of auricular haematoma.

Adolescent↗
PubMedDate not supplied

[Chemical and physical characteristics and toxicology of man-made mineral fibers].

The evidence for the adverse health effects following exposure to asbestos (i.e. fibrogenic and carcinogenic effect) has prompted widespread removal of asbestos-containing materials and led to banning of asbestos internationally (in Italy, DPR 257/1992), resulting in the increased use of substitutes composed of both naturally occurring and synthetic materials, including man made mineral fibres (MMMFs) and man made organic fibres (MMOF). MMMFs represent a family of synthetic, inorganic vitreous substances derived primarily from glass, rock, slag, or clay. MMMFs are further divided into two categories: 1) man made vitreous fibres (MMVFs), further divided as follows: a) fibrous glass, including mainly continuous filament, special purpose fibres; and microfibres. The materials are typically composed of oxides of silicon, calcium, sodium, potassium, aluminum, and boron. b) Mineral wool, including glass wool, rock wool (derived from magma rock) and slag wool (made from molten slag produced in metallurgical processes such as the production of iron, steel, or copper). The main components of rock wool and slag wool are oxides of silicon, calcium, magnesium, aluminum, and iron. 2) Refractory/ceramic fibres, amorphous or partially crystalline materials made from kaolin clay or oxides of aluminum, silicon or other metal oxides (i.e. oxides of zirconium and yttrium). Less commonly, refractory fibres are also made from non-oxide refractory materials such as silicon carbide, silicon nitride, or boron nitride. Industrial production of MMVFs began in the second half of the 19th century, while ceramic fibres production began more recently, in the early 1970s. Major uses of MMMFs include thermal, acoustic and aerospace insulation, fire proofing, reinforcing material in plastics, cement and textile, optic fibres, air and liquid filtration, friction products, refractory coatings. Serious questions have been raised about health implications of MMMFs. Suspicion about the possible occurrence of adverse effects following exposure to MMMFs arises mainly from some similarities of MMMFs with asbestos (fibrous aspects, inhalability, chemical composition, free radical formation). The fibre characteristics that have been identified as crucial in influencing the pathogenesis of fibre-related adverse respiratory effects can be mainly divided into two groups: fibre dimension, and chemical composition and structure. Fibre dimension plays a determining role in conditioning penetration in the lung. In a broad sense, the term "respirable" means "capable of being carried by breath into the respiratory system". For regulatory purposes, "respirable fibres" (i.e. RFP) are defined in most countries following WHO criteria: length > 5 microns, diameter < 3 microns, length/diameter > 3. MMMFs are generally produced as fibres of diameter higher than asbestos, and too large in diameter to be respirable. Moreover, due to the production process, they are structurally amorphous. Since MMMFs have no crystalline domains, they also have no clearly defined structural faults and they fracture transversely, and randomly. Fragments that are too large to be taken up by macrophages can be resolved in the lung by a leaching--or dissolution--process which leads to a progressive reduction of particle length. In contrast, when abraded, asbestos tends to split longitudinally into new, fine, straight fibres: these fibrils are of much smaller diameter, more respirable, and consequently more hazardous than parent fibres. Fibre chemical composition plays a determining role in conditioning the higher or lower biological activity, durability, biopersistence, and biodegradability. The term "biological activity" means reactivity or ability to interact (possibly due to formation of active oxygen species, identified as a crucial step in the mechanism of action) with biological structures and tissues. Fibre "durability" is strictly related to its solubility. It can be defined as the ability to resist

Animals↗
PubMed1988

[Retinographic and angiographic study of ocular lesions detected in AIDS].

We examined 42 patients with the acquired immune deficiency syndrome: 11 of these had retinal lesions. In this study we reported five cases; all were examined within several weeks of admission to the Maggiore Hospital, and at various intervals thereafter. Ophthalmic evaluation included determination of visual acuity, slit-lamp examinations, direct ophthalmoscopy with the pupil dilated, fundus photography and fluorescein angiography. Peripheral blood mononuclear cells were isolated during gradient density centrifugation. Lymphocyte subsets were determined by immunofluorescence with monoclonal antibodies of the OKT series. All patients demonstrated a reduction of the ratio of T-helper to T-suppressor. Patient no. 1 was a 41 year-old hemophiliac man became ill (ARC) in June 1986; initially the patient had no ocular lesions. After five months developed bilateral retinal cotton wool spots. The patient's clinical conditions progressively worsened during the ensuing months and after fifteen months he felt a decreased vision in left eye: retinal examination disclosed a presumed CMV retinitis. Patient no. 2 was a 30 year-old intravenous drug-user man. At the time of the admission (AIDS) ophthalmologic evaluation revealed multiple cotton wool spots in both eyes. These changed of number and size during the following months. This patient was treated with ganciclovir (dihydroxy propoxymethyl guanine) because developed a CMV encephalopathy. We noted after this treatment a strong reduction of the cotton wool spots without an improvement of the general conditions and he died a month later. Patient no. 3 was a 26 year-old drug-user woman admitted for ARC. Ophthalmologic evaluation disclosed in right eye a presumed CMV retinitis with vascular sheathing and hemorrhages, and in left eye a little white retinal lesion (an initial retinitis) and cotton wool spots. The general and the retinal conditions rapidly worsened and she died three months later. Patient no. 4 was a 24 year-old women, intravenous drug-user, admitted for AIDS complicated by central nervous system infection by Toxoplasmic Gondii. Ocular examination revealed in right eye retinal cotton wool spots, and in left eye a white chorioretinal lesion with vitritis attributed to Toxoplasma Gondii. This retinochoroiditis improved after empiric therapy with sulfonamides and pyrimethamine. Patient no. 5 was a 37 year-old bisexual man admitted for AIDS. The findings on ophthalmologic examination were: CMV retinitis in right eye and retinal cotton wool spots in left eye. Treatment with ganciclovir resulted in an improvement of general symptoms.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1986

The man-made mineral fiber European historical cohort study. Extension of the follow-up.

The study concentrated on 21,967 workers producing rock wool/slag wool, glass wool or continuous filament in 13 European factories. The expected deaths and incident cancer cases were derived from multiplying the accumulated person-years by national reference rates across sex, age, and calendar-year strata, correction factors for regional lung cancer mortality also being used. Exposure assessment was based on the results of a historical environmental investigation reported elsewhere. There were 189 deaths (151.2 expected), and for rock-wool/slag-wool and glass-wool workers the standardized mortality ratios for lung cancer showed a pattern of increasing mortality with time since first exposure but not duration of employment. There was an excess of lung cancer among rock-wool/slag-wool workers employed during an early technological phase before the introduction of dust-suppressing agents, and fiber exposure, either alone on in combination with other exposures, may have contributed to the elevated risk. No excess of the same magnitude was evident for glass-wool production, and the follow-up of the continuous filament cohort was too short to allow for an evaluation of possible long-term effects. There was no evidence of an increased risk for pleural tumors or nonmalignant respiratory diseases.

Calcium Compounds↗
PubMed1981

Glucocorticoid receptor content of T lymphocytes: evidence for heterogeneity.

Glucocorticoid receptors were measured in T lymphocytes that were isolated from peripheral blood by either nylon wool filtration or E-rosette sedimentation. T cells isolated by nylon wool filtration specifically bind 6.7 +/- 0.2 fmol of dexamethasone per million cells (equivalent to 4000 +/- 200 receptors per cell), whereas T cells isolated by E-rosette sedimentation bind 12.0 +/- 0.7 fmol of dexamethasone per million cells (equivalent to 7200 +/- 400 receptors per cell). This difference in the amount of dexamethasone bound by the two T cell preparations was significant (p less than .001) and was present immediately after cell isolation. The binding affinities of the different T cell preparations for dexamethasone were similar. T cells that are isolated by a combination of nylon wool filtration followed by E-rosette sedimentation bind the same amount of dexamethasone as T cells isolated by nylon wool filtration alone. T cells isolated by a combination of E-rosette sedimentation following by nylon wool filtration bind less dexamethasone than do T cells isolated by E-rosette sedimentation alone. These findings suggest that T cells are heterogeneous with respect to their quantity of glucocorticoid receptors. Isolation of T cells by E-rosette sedimentation enriches for T cells that have a greater number of glucocorticoid receptors, and isolation of T cells by nylon wool filtration enriches for T cells that have a lesser number of glucocorticoid receptors.

Binding Sites↗
PubMed1994

Ocular microangiopathic syndrome in patients with acquired immunodeficiency syndrome and its relationship to alterations in cell adhesion and in blood flow.

Ocular microangiopathic syndrome is the most frequent ophthalmic finding in patients with acquired immunodeficiency syndrome (AIDS). Ocular microvascular changes, including cotton-wool spots, are closely associated with neuroretinal and cognitive deficits in patients infected with the human immunodeficiency virus type 1 (HIV-1). Cell adhesion has become an important pathogenetic concept in infectious diseases. We studied 39 patients with AIDS by indirect ophthalmoscopy and by slit-lamp biomicroscopy. Cotton-wool spots were counted as an indicator of retinal microvasculopathy. Conjunctival blood-flow sludging in conjunctival vessels was determined by a standardized rating scale as an indicator of blood-cell adhesion abnormalities. Parameters of immunosystemic damage were determined by fluorescein-activated cell-sorter scan, radioimmunoassay, and enzyme-linked immunosorbent assay. Conjunctival blood-flow sludging was present in 92% of our patients, and cotton-wool spots were observed in 44%. Cotton-wool spots occurred only in patients with significant blood-flow sludging, and the quantity of cotton-wool spots was closely associated with blood-flow sludging (r = 0.64, P < 0.0001). Lower correlations were found between the numbers of cotton-wool spots and the serum level of neopterin (r = 0.40, P = 0.01) or the CD4+ count (r = -0.39, P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1993

HIV-related ocular microangiopathic syndrome and cognitive functioning.

Ocular microangiopathic syndrome is found frequently in patients with AIDS or severe HIV infection. Symptoms of this microvascular syndrome can include cotton-wool spots, hemorrhages, and Roth's spots. The clinical and functional significance of HIV-related ocular microangiopathic syndrome has not been clarified as yet. The objective of this study was to evaluate a possible association between HIV-related ocular microangiopathic syndrome and cognitive functioning. Thirty-seven patients infected with HIV (24 with AIDS) underwent ophthalmological and neuropsychological examination. HIV-related ocular microangiopathic syndrome was measured by counting the number of cotton-wool spots in both eyes. Neuropsychological examination included five standardized tests, with the first three primarily measuring function of short-term memory; these tests were as follows: the Auditory-Verbal Learning Test, the Benton Test, the Stroop Colour Word Test, the Trail-Making Part B test, and the Vocabulary for Measuring Premorbid Intelligence test. HIV-related ocular microangiopathic syndrome was found in 15 patients with AIDS (62.5%), and in one patient, staged Walter Reed 5. In 10 patients, one eye was affected (mean count of cotton-wool spots 1.5). In six patients, both eyes were affected (mean count of cotton-wool spots 7.0). Univariate correlations between the number of cotton-wool spots in both eyes and test scores were as follows: Auditory-Verbal Learning Test: 0.56 (p < 0.001); Benton Test: 0.51 (p < 0.001); Stroop Colour and Word: 0.50 (p < 0.001); Trail-Making Part B: 0.15 (not significant); Vocabulary for Measuring Premorbid Intelligence: -0.05 (not significant). Multiple correlation between the test scores and the number of cotton-wool spots was 0.70 (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The effect of acute and chronic administration of the beta-agonist, cimaterol, on protein synthesis in ovine skin and muscle.

The action of intravenous infusion of the beta-agonist cimaterol (2.5 mg/d) on whole-body N retention and protein synthesis in peripheral tissues was examined in growing sheep. Wool growth was determined from skin patch clippings and adjusted to total fibre production. Protein synthesis was measured, using sequential large dose injections of [1-13C]valine, leucine and phenylalanine and then [ring-d5]phenylalanine, on biopsy samples from skin and m. longissimus dorsi taken before beta-agonist administration, at day 3 and day 15 of cimaterol infusion, and 15 d after withdrawal of the drug. Cimaterol increased total N retention by 1.9-2.3 g N/d (P < 0.01) over three successive 5 d periods. In contrast, wool growth was significantly reduced by 0.7 g N/d (P < 0.001) and the proportion of total N retained in wool declined from 0.71 to 0.25 (P < 0.01). The reduction in wool growth was accompanied by a decrease in protein fractional synthesis rate (FSR) in skin (11.6 v. 6.3%/d, P < 0.01). Muscle protein FSR, on the other hand, was markedly stimulated during cimaterol infusion (1.45 v. 3.01%/d, P < 0.001) as was RNA concentration (P < 0.001), RNA:protein (P < 0.001) and protein:DNA (P < 0.05). The estimated increase in total protein synthesis in muscle (+24 to 30 g/d) due to cimaterol administration was counterbalanced by reductions for skin (-25 to 27 g/d); this may account for the lack of changes in whole-body protein synthesis following beta-agonist administration reported in other studies. Although N retention rapidly returned to control values following withdrawal of the drug, both wool growth and skin protein synthesis remained depressed, while muscle protein FSR declined, but not to pre-treatment values. These results suggest a persistent action of cimaterol, but whether this is a function of residue concentrations or long-term metabolic responses is not known.

Adrenergic beta-Agonists↗
PubMedDate not supplied

The protection against and treatment of a liquid propane freeze injury: an experimental model.

Liquid propane causes a severe, deep thermal injury in unprotected tissue. Delayed surgical intervention, as for thermal burns, has been the gold standard of treatment. An animal model of liquid-propane injury was devised to document injury, to demonstrate a better method of protection, and to define an appropriate management protocol. Twenty-eight rats were classified into four groups: unprotected tissue (n = 8), skin covered with wool (n = 8), skin covered with Neoprene (Wm. H. Horn & Brothers Inc., Philadelphia, Pa.) (n = 8), and skin covered with wool plus Neoprene (n = 4). Each group was subdivided into two exposure times: 6 seconds and 30 seconds. The mean temperatures +/- standard error of the mean of the various tissue levels initially and at 6 and 30 seconds of exposure were determined. Histologic examination demonstrated that full-thickness tissue necrosis occurred in unprotected and wool-covered tissue. Areas that were covered with Neoprene showed intact skin and subcutaneous tissue with underlying muscle necrosis. Examination of the tissue that was covered with wool plus Neoprene showed no histologic damage. There was no sign of tissue regeneration at the wound periphery, and there was no histologic difference in any group, whether the examination took place at 1 or 5 days after injury. This study demonstrated that the best form of protection appears to be a wool glove liner covered with a Neoprene glove. The histologic evidence suggests that a liquid-propane injury to unprotected tissue should be managed aggressively with early excision and grafting.

Animals↗
PubMed1981

The ovipositional response of the Australian sheep blowfly, Lucilia cuprina, to fleece-rot odours.

The ovipositional response of Lucilia cuprina flies to odours emanating from fleece-rot lesions of greasy wool in which Pseudomonas aeruginosa bacteria proliferated, was studied. Fractionation of the fleece-rot odours was carried out by bubbling the volatile components through hydrochloric acid and sodium hydroxide solutions to remove basic odours and acidic odours respectively. It was found that the acidic/neutral odours of fleece-rot wool, when perfused into wet, greasy wool stimulated L. cuprina to oviposit. On the other hand, the basic/neutral odours of fleece-rot wool were virtually unattractive to the gravid fly. Similarly, the acidic/neutral odours emanating from fleece-rot lesions of clean wool from which the non-fibre components, wax, suint and epithelial debris, had been removed by scouring, were found to be unattractive to the gravid fly in choice tests.

Animals↗
PubMed1993

Production, behaviour and fertility of merino wethers, hemi-castrates with reduced testicular parenchyma and induced cryptorchids.

Greasy wool production, body weight, behaviour and fertility of male, fine wool Merino sheep were studied from 10 to 21 months of age to assess their suitability for wool production. The males were either castrated (wethers), or were hemi-castrated with a vasectomy and reduction (either partially or in full) of the parenchyma of the retained testicle, or the testicles pushed up into the inguinal canal and the scrotum shortened (induced cryptorchids). There were significant differences among all groups in body weight, with increases being associated with the larger amounts of testicular tissue present. Fertility was low in the induced cryptorchids at 19 months of age. The hemi-castrates with reduced testicular parenchyma were infertile. The hemi-castrates with reduced testicular parenchyma had significantly heavier greasy fleece weights than the wethers and induced cryptorchids, which had similar fleece weights. The wether group suffered a higher prevalence of posthitis in spring and autumn than the hemi-castrate or induced cryptorchid groups. Those hemi-castrates with the largest amount of testicular parenchyma retained and the induced cryptorchids exhibited masculine behaviour patterns and had an increased incidence of fly strike to the head. The principle of hemi-castration and reduction of the testicular parenchyma is shown to be applicable in wool producing flocks with the potential to increase greasy wool production while minimising the management and marketing limitations previously associated with induced cryptorchids.

Animals↗
PubMed1979

On splitting plasters. A useful analogy.

An inner tube was inflated and then surrounded with plaster wool and plaster-of-Paris bandages. The plaster and the wool were next progressively divided. There was no significant reduction of the pressure inside the tube until both the plaster and the wool had been divided and separated from the inner tube along the entire circumference. These findings demonstrated that wool and plaster applied to limbs likely to swell should be split right down to skin and widely separated immediately after their application. A plaster slab is safer still, but the wool must be cut before the crepe bandage is applied.

Animals↗
PubMed2004

Large volume splitless injection with concurrent solvent recondensation: keeping the sample in place in the hot vaporizing chamber.

An injector liner packed with a plug of glass wool is compared with a laminar and a mini laminar liner for large volume (20-50 microL) splitless injection with concurrent solvent recondensation (CSR-LV splitless injection). Videos from experiments with perylene solutions injected into imitation injectors show that glass wool perfectly arrested the sample liquid and kept it in place until the solvent had evaporated. The sample must be transferred from the needle to the glass wool as a band, avoiding 'thermospraying' by partial solvent evaporation inside the needle. The liquid contacted the liner wall when the band was directed towards it, but from there it was largely diverted to the glass wool. In the laminar liners, part of the liquid remained and evaporated at the entrance of the obstacle, while the other proceeded to the center cavity. Vapors formed in the center cavity drove liquid from the entrance of the obstacle upwards, but the importance of such problems could not be verified in the real injector. Some liquid split into small droplets broke through the obstacle and entered the column. Breakthrough through the laminar liners was confirmed by a chromatographic experiment. An improved design of a laminar liner for large volume injection is discussed as a promising alternative if glass wool causes problems originating from insufficient inertness.

Journal Article↗
PubMed1995

Chronic inhalation studies of man-made vitreous fibres: characterization of fibres in the exposure aerosol and lungs.

Inhalation studies were conducted to determine the chronic biological effects in rodents of respirable fractions of different man-made vitreous fibres (MMVFs), including refractory ceramic fibre (RCF), fibrous glass, rock (stone) wool and slag wool. Animals were exposed nose-only, 6 h per day, 5 days per week, for 18 months (hamsters) or 24 months (rats). Exposure to 10 mg m-3 of crocidolite or chrysotile asbestos induced pulmonary fibrosis, lung tumours and mesothelioma in rats, thus validating the inhalation model with known human carcinogenic fibres. Exposure of rats to 30 mg m-3 of refractory ceramic fibres (RCF) also resulted in pulmonary fibrosis as well as significant increases in lung tumours and mesothelioma. In hamsters, 30 mg m-3 of RCF induced a 41% incidence of mesotheliomas. Exposure of rats to 30 mg m-3 of fibre glasses (MMVF 10 or 11) or of slag wool (MMVF 22) was associated with an inflammatory response, but no mesotheliomas or significant increase in the lung tumours were observed. Rock wool (stone wool: MMVF 21) at the same exposure level resulted in minimal lung fibrosis, but no mesotheliomas or significant increase in the lung tumours were observed. Fibre numbers (WHO fibres) and dimensions in the aerosols and lungs of exposed animals were comparable in this series of inhalation studies. Differences in lung fibre burdens and lung clearance rates could not explain the differences observed in the toxicologic effects of the MMVFs. These findings indicate that dose, dimension and durability may not be the only determinants of fibre toxicity. Chemical composition and the surface physico-chemical properties of the fibres may also play an important role.

Aerosols↗
PubMed1995

Statistical analysis of results of carcinogenicity studies of synthetic vitreous fibres at Research and Consulting Company, Geneva.

Five inhalation studies of synthetic vitreous fibres have recently investigated experimental tumorigenic responses to four different refractory ceramic fibres (RCF), two fibre glasses, one stone (rock) wool and one slag wool. Except for one RCF, the source materials were typical commercial products. Three studies included positive control groups exposed to chrysotile or crocidolite asbestos. The studies were conducted using state-of-the-art technologies for fibre size separation, fibre lofting and nose-only inhalation exposure. The target average fibre size was 20 microns long by 1 micron diameter. Hamsters exposed to a kaolin RCF yielded a mesothelioma rate of 38%, but no lung cancers. There were no tumours among the chrysotile-exposed hamsters. At the highest dose of 30 mg m-3 in rat studies, the commercial RCF all produced significant numbers of lung tumours, and some mesotheliomas. The fourth RCF, which had been heat-treated to simulate an after-service fibre, did not produce a significant excess of lung cancers, but did produce one mesothelioma. A rat multi-dose experiment with three lower doses of the kaolin RCF yielded one mesothelioma among 379 rats, but no excess of lung tumours. The overall dose-response relation for lung cancer did not appear to be linear, consistent with the possibility of a threshold close to the Maximum Tolerated Dose. No insulation wool (glass, stone or slag) exposure group had a lung tumour rate that differed statistically significantly from the tumour rate for the respective concurrent control groups, sham-exposed to filtered air. There was no significant difference in the total tumour rates between the four insulation wool groups and the control animals, and no significant dose-response relation above the respective sham-exposed control tumour rates. The total lung tumour rates for rats in both chrysotile and crocidolite exposure groups were significantly raised. One animal in each asbestos-exposed group developed a mesothelioma, whereas no air control or insulation wool-exposed animal did so.

Animals↗
PubMed2004

Man-made mineral (vitreous) fibres: evaluations of cancer hazards by the IARC Monographs Programme.

Man-made vitreous (glass-like) fibres are non-crystalline, fibrous inorganic substances (silicates) made primarily from rock, slag, glass or other processed minerals. These materials, also called man-made mineral fibres, include glass fibres (used in glass wool and continuous glass filament), rock or stone wool, slag wool and refractory ceramic fibres. They are widely used for thermal and acoustical insulation and to a lesser extent for other purposes. These products are potentially hazardous to human health because they release airborne respirable fibres during their production, use and removal. Man-made mineral fibres and man-made vitreous fibres have been the subject of reviews by IARC Monographs Working Groups in 1987 and 2001, respectively, which resulted in evaluations of the carcinogenic hazard to humans from exposure to these materials. These reviews and evaluations have been published as Volumes 43 and 81 of the IARC Monographs series [IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 43, Man-made Mineral Fibres and Radon (1988); IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 81, Man-made Vitreous Fibres (2002)]. The re-evaluation in 2001 was undertaken because there have been substantial improvements in the quality of the epidemiological information available on the carcinogenicity to humans of glass fibres, continuous glass filament and rock/slag wool. The new evaluations have addressed the limitations of earlier cohort studies, particularly concerning the lack of adjustment with respect to concomitant risk factors such as smoking and other sources of occupational exposure. In addition, the evaluation of the evidence for carcinogenicity of glass fibres to experimental animals has been refined, by making a distinction between insulation glass wool and special-purpose glass fibres. The results of the evaluations in 1987 and 2001 are thus different in several aspects. In this paper, the reviews and evaluations of the carcinogenic hazards of exposure to man-made mineral fibres (MMMF, Monograph volume 43, [1]) and man-made vitreous fibres (MMVF, Monograph volume 81, [2]) are summarised, and the differences explained. In particular, the considerations of the respective IARC Monographs Working Groups (1987, 2001) in reaching their conclusions are discussed in some detail.

Animals↗
PubMed2001

Comparisons of oocyte maturation times and of three methods of sperm preparation for their effects on the production of goat embryos in vitro.

Various times of in vitro maturation of oocytes, and three methods of separating spermatozoa from frozen-thawed semen (Percoll density-gradient centrifugation, swim-up, and glass-wool filtration), were compared for their effects on goat embryo production in vitro. Cumulus-oocyte-complexes (COCs) from abattoir ovaries were matured in M199 supplemented with 10% fetal calf serum and hormones. In Experiment 1, COCs were fixed at 4 h intervals from 0 to 27 h of culture to assess oocyte nuclear maturation. A higher proportion cultured for 27 h than for 24 h were in Metaphase II (27/37, 73% vs. 18/33, 55%, P < 0.05). In Experiment 2, the effects of separation methods on total numbers and numbers of membrane-intact spermatozoa, and the acrosome reaction were compared. Total numbers after Percoll density-gradient centrifugation were approximately 4 times higher than after swim-up and approximately 2 times higher than after glass-wool filtration (P < 0.001). Progression of the acrosome reaction was not affected differentially. In Experiments 3 and 4, after 27 h of culture the COCs were inseminated with sperm isolated by the three methods. In Experiment 3, presumptive zygotes were examined for pronucleus (PN) formation at 6, 12, 18 and 24 h post-insemination. At 12 h, male PN formation rate from Percoll-treated spermatozoa was higher than from sperm subjected to swim-up and glass-wool treatments (20/37, 54% vs. 6/37, 16% and 6/38, 16%, respectively; P < 0.001). In Experiment 4, embryos were compared for cleavage at 48 h and development into blastocysts, hatching rates and cell number at 192 h. The rates of cleavage and blastocyst formation in the Percoll-treated group were higher (P < 0.05) than in the swim-up and glass-wool groups (62% and 18% vs. 50% and 11%, and 45% and 8%, respectively). Similarly, the mean cell number in the Percoll group was higher (P < 0.05) than in the swim-up and glass-wool groups (167 +/- 5 vs. 149 +/- 4 and 126 +/- 4, respectively). We conclude that Percoll density-gradient centrifugation is superior to the other two methods for separating goat spermatozoa from frozen-thawed semen in preparation for IVF.

Acrosome↗