Beryllium metal I. experimental results on acute oral toxicity, local skin and eye effects, and genotoxicity.

The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral toxic properties.

Reversal of effects of intra peritoneally administered beryllium nitrate by tiron and CaNa3DTPA alone or in combination with alpha-tocopherol.

To evaluate therapeutic efficacy of chelating agents tiron (Sodium-4,5-dihydroxy-1,3-benzene disulphonate) and CaNa3DTPA (Calcium trisodium diethylene triamine pentaacetic acid) in presence of alpha-tocopherol against beryllium induced toxicity, adult female albino rats were exposed to beryllium nitrate for 28 days followed by therapy with tiron (471 mg/kg, i.p.) and CaNa3DTPA (35 mg/kg, i.p.) alone and in combination with alpha-tocopherol (25 mg/kg, p.o.). Results revealed non-significant fall in haemoglobin and total serum protein content while significant fall in blood sugar level and activity of serum alkaline phosphatase. On the other hand, significant rise in the activity of serum transaminases and LDH was noticed after beryllium administration. Significant increase in total and esterified cholesterol was found in liver and kidney after toxicity. Significant increase in lipid peroxidation and decreased level of reduced glutathione in both the organs showed oxidative stress due to beryllium exposure. Histopathological and ultrastructural observations of liver and kidney revealed lesions due to beryllium toxicity followed by recovery due to combined therapy. CaNa3DTPA showed moderate therapeutic efficacy; however, its effectiveness was enhanced with alpha-tocopherol to some extent. Tiron in combination with alpha-tocopherol exerted statistically more beneficial effects in reversal of beryllium induced biochemical, histopathological and ultrastructural alterations.

Dermal exposure to beryllium: a pilot case study.

The issue of dermal absorption of beryllium (Be) particles through intact healthy skin has not yet been demonstrated. The interest in Be dermal exposure as a potential pathway for toxic effects was emphasized in Quebec (Canada) when a recycling industry processing spent pot lining (SPL) related to the aluminum industry was recently requested by health authorities to conduct a Be particle size study and to provide a Tyvek coverall for full skin protection of workers. This study aimed to (1) calculate the dermal and inhalation exposures and (2) apply the results to the case study of a recycling SPL industry. Airborne dust was sampled in order to determine Be particles size. Exposure assessment via the skin and the respiratory routes was measured over a working day using standard calculations. The assessment of workers' clothing protection was obtained by swiping the skin on the forearm and upper front leg before and after exposure. Respirable Be (0.044 microg) was 23% of the total Be (0.19 microg). Be particles with a median mass aerodynamic diameter (MMAD) of 0.93 and below totaled 0.0103 microg (5% of BeT). The daily dose for the respiratory route was calculated to be 0.022 microg/kg/d, while the daily doses for the dermal route varied between 0.027 x 10(-7) microg/kg/d and 0.025 x 10(-3) microg/kg/d. After exposure, no Be was found on the skin of workers wearing a cotton coverall protection. When using a polyester coverall, minor amounts of Be were found. These results showed that dermal daily dose exposure is negligible. However, note that the case study did not involve handling of contaminated items by the workers, which lead to significant dermal exposure if care is not taken. Although daily dermal exposure may be small, because of uncertainties, a precautionary principle should be applied in an active sense.

[Toxicologic characteristics of ammonium fluoroberyllate and its distribution in body after various intake methods].

The authors present materials on toxic influence and distribution of ammonium fluoroberyllate after various intake ways in white rats, on decontamination of skin wound surface.

A review of workplace aerosol sampling procedures and their relevance to the assessment of beryllium exposures.

Standardized conventions governing the fractions of airborne particles that can penetrate the human head airways, the thoracic airways and the alveolar spaces have been internationally (although not universally) adopted. Several agencies involved in setting limit values for occupational exposure concentrations have taken these conventions into account when considering the appropriate standard for specific chemicals, in order to ensure the standards are biologically relevant. A convention is selected based on the characteristic health effects, and forms the basis of measurement against the limiting concentration value. In order to assess exposure for comparison to this metric or any other purposes, it is necessary to choose a sampler whose performance matches the convention, and protocols have been developed and used to test sampler performance. Several aerosol sampling devices are available, nominally at least, for each of the conventions. Some considerations important to the sampling of airborne particles containing beryllium with regard to the sampling conventions, the test protocols and sampler performance are discussed.

Skin as a route of exposure and sensitization in chronic beryllium disease.

Chronic beryllium disease is an occupational lung disease that begins as a cell-mediated immune response to beryllium. Although respiratory and engineering controls have significantly decreased occupational beryllium exposures over the last decade, the rate of beryllium sensitization has not declined. We hypothesized that skin exposure to beryllium particles would provide an alternative route for sensitization to this metal. We employed optical scanning laser confocal microscopy and size-selected fluorospheres to demonstrate that 0.5- and 1.0- micro m particles, in conjunction with motion, as at the wrist, penetrate the stratum corneum of human skin and reach the epidermis and, occasionally, the dermis. The cutaneous immune response to chemical sensitizers is initiated in the skin, matures in the local lymph node (LN), and releases hapten-specific T cells into the peripheral blood. Topical application of beryllium to C3H mice generated beryllium-specific sensitization that was documented by peripheral blood and LN beryllium lymphocyte proliferation tests (BeLPT) and by changes in LN T-cell activation markers, increased expression of CD44, and decreased CD62L. In a sensitization-challenge treatment paradigm, epicutaneous beryllium increased murine ear thickness following chemical challenge. These data are consistent with development of a hapten-specific, cell-mediated immune response following topical application of beryllium and suggest a mechanistic link between the persistent rate of beryllium worker sensitization and skin exposure to fine and ultrafine beryllium particles.

High beryllium-stimulated TNF-alpha is associated with the -308 TNF-alpha promoter polymorphism and with clinical severity in chronic beryllium disease.

Beryllium (Be)-antigen stimulates tumor necrosis factor-alpha (TNF-alpha) from bronchoalveolar lavage (BAL) cells in chronic beryllium disease (CBD). This study tested the hypothesis that high concentrations of Be-stimulated TNF-alpha are related to polymorphisms in the TNF-alpha promoter and clinical markers of disease severity in CBD. Demographic and clinical information was obtained from patients with CBD (n = 20). TNF-alpha concentrations were measured in BAL cell culture supernatant by ELISA. A priori, we categorized CBD subjects as either high or low TNF-alpha producers using a cutoff of 1,500 pg/ml. The TNF-alpha promoter sequence, +64 to -1045, was determined by direct sequencing. Human leukocyte-associated antigen (HLA)-DPB1 and -DRB1 genotyping was determined by polymerase chain reaction (PCR). High Be-stimulated TNF-alpha was associated with TNF2 alleles, Hispanic ethnicity, presence of HLA-DPB1 Glu69, and absence of HLA-DR4. Be-stimulated TNF-alpha concentrations correlated with markers of disease severity, including chest radiograph, beryllium lymphocyte proliferation, and spirometry. We found no novel TNF-alpha promoter polymorphisms. These data suggest that the TNF2 A allele at -308 in the TNF-alpha promoter region is a functional polymorphism, associated with a high level of Be-antigen-stimulated TNF-alpha and that these high TNF-alpha levels indicate disease severity in CBD.

Particle clearance and histopathology in lungs of C3H/HeJ mice administered beryllium/copper alloy by intratracheal instillation.

Beryllium/copper (BeCu) alloys are commonly used in the electronics, automotive, consumer, defense, and aerospace industries. Some individuals exposed occupationally to BeCu alloys have developed chronic beryllium disease. However, little is known of the toxicity and fate of BeCu alloys in the respiratory tract. To begin to address this question, we investigated the pulmonary toxicity and clearance of BeCu alloy (2% Be; 98% Cu) in mice. Groups of 40 female C3H/HeJ mice were administered 12.5, 25, and 100 microg BeCu alloy or 2 and 8 microg Be metal by intratracheal instillation. Mice were sacrificed at 1 h and 1, 7, 14, and 28 days postinstillation. Left lungs were evaluated for histopathological change. Right lungs were analyzed for Be and Cu content. Twenty-five percent of the high-dose BeCu mice and 7.5% of the mid-dose BeCu mice died within 24 h of dosing. Acute pulmonary lesions included acute alveolitis and interstitial inflammation. Type II epithelial cell hyperplasia and centriacinar fibrosis were present by 7 days after dosing. Lesions persisted through 28 days after instillation. No lesions attributable to alloy exposure were present in liver or kidney. Be metal instillation caused no deaths and minimal pulmonary changes over the time studied, indicating that the pulmonary lesions were due to Cu rather than Be. Cu cleared the lung with a half-time of 0. 5-2 days. Be cleared with a half-time of several weeks or longer. Results of this study suggest that exposure to BeCu alloy is more acutely toxic to lung than Be metal. The results of tissue analyses also indicate that, while the Cu component of the alloy clears the lung rapidly, Be is retained and may accumulate upon repeated exposure.

Beryllium, an adjuvant that promotes gamma interferon production.

Beryllium is associated with a human pulmonary granulomatosis characterized by an accumulation of CD4(+) T cells in the lungs and a heightened specific lymphocyte proliferative response to beryllium (Be) with gamma interferon (IFN-gamma) release (i.e., a T helper 1 [Th1] response). While an animal model of Be sensitization is not currently available, Be has exhibited adjuvant effects in animals. The effects of Be on BALB/c mice immunized with soluble leishmanial antigens (SLA) were investigated to determine if Be had adjuvant activity for IFN-gamma production, an indicator of the Th1 response. In this strain of Leishmania-susceptible BALB/c mice, a Th2 response is normally observed after in vivo SLA sensitization and in vitro restimulation with SLA. If interleukin-12 (IL-12) is given during in vivo sensitization with SLA, markedly increased IFN-gamma production and decreased IL-4 production are detected. We show here that when beryllium sulfate (BeSO(4)) was added during in vivo sensitization of BALB/c mice with SLA and IL-12, significantly increased IFN-gamma production and decreased IL-4 production from lymph node and spleen cells were detected upon in vitro SLA restimulation. No specific responses were observed to Be alone. Lymph node and spleen cells from all mice proliferated strongly and comparably upon in vitro restimulation with SLA and with SLA plus Be; no differences were noted among groups of mice that received different immunization regimens. In vivo, when Be was added to SLA and IL-12 for sensitization of BALB/c mice, more effective control of Leishmania infection was achieved. This finding has implications for understanding not only the development of granulomatous reactions but also the potential for developing Be as a vaccine adjuvant.

Carcinogenic responses of transgenic heterozygous p53 knockout mice to inhaled 239PuO2 or metallic beryllium.

The transgenic heterozygous p53+/- knockout mouse has been a model for assessing the tumorigenicity of selected carcinogens administered by noninhalation routes of exposure. The sensitivity of the model for predicting cancer by inhaled chemicals has not been examined. This study addresses this issue by acutely exposing p53+/- mice of both sexes by nose-only inhalation to either air (controls), or to 1 of 2 levels of 239PuO2 (500 or 100 Bq 239Pu) or beryllium (Be) metal (60 or 15 micrograms). Additional wild-type p53+/+ mice were exposed by inhalation to either 500 Bq of 239PuO2 or 60 micrograms of Be metal. These carcinogens were selected because they operate by differing mechanisms and because of their use in other pulmonary carcinogenesis studies in our laboratory. Four or 5 of the 15 mice per sex from each group were sacrificed 6 mo after exposure, and only 2 pulmonary neoplasms were observed. The remainder of the mice were held for life-span observation and euthanasia as they became moribund. Survival of the p53+/- knockout mice was reduced compared to the p53+/+ wild-type mice. No lung neoplasms were observed in p53+/- mice exposed to air alone. Eleven of the p53+/- mice inhaling 239PuO2 developed pulmonary neoplasms. Seven p53+/+ mice exposed to 239PuO2 also developed pulmonary neoplasms, but the latency period for pulmonary neoplasia was significantly shorter in the p53+/ mice. Four pulmonary neoplasms were observed in p53+/- mice exposed to the higher dose of Be, whereas none were observed in the wild-type mice or in the heterozygous mice exposed to the lower dose of Be. Thus, both p53+/- and p53+/+ mice were susceptible to 239Pu-induced carcinogenesis, whereas the p53+/- but not the p53+/+ mice were susceptible to Be-induced carcinogenesis. However, only 2 pulmonary neoplasms (1 in each of the 239PuO2 exposure groups) were observed in the 59 p53+/ mice that were sacrificed or euthanatized within 9 mo after exposure, indicating that the p53+/- knockout mouse might not be appropriate for a 6-mo model of carcinogenesis for these inhaled carcinogens.

Expansions of T-cell subsets expressing particular T-cell receptor variable regions in chronic beryllium disease.

Chronic beryllium disease (CBD) is a granulomatous disorder characterized by the presence of noncaseating granulomas and mononuclear cell inflammation, occurring in 1 to 5% of people exposed to beryllium in the workplace. In the lungs of affected patients, CD4(+) T cells accumulate. Using anti-T-cell receptor (TCR) monoclonal antibodies, we investigated the TCR beta and alpha variable (Vbeta and Valpha, respectively) repertoire in the bronchoalveolar lavage (BAL) and blood of both CBD patients and healthy controls. There was marked heterogeneity within the BAL CD4(+) T-cell repertoire in both patients and controls. However, 11 of the 28 CBD patients demonstrated 16 different T-cell subset expansions within the BAL as compared with only one expansion in ten healthy controls. Five of the 16 expansions in CBD patients expressed Vbeta3. Altered TCR expression within the BAL T-cell repertoire appeared to persist over time in patients who underwent repeat evaluation. After in vitro stimulation of BAL T cells with beryllium sulfate and interleukin-2, we noted further alteration of the BAL TCR repertoire in some individuals. These results provide additional insight into the involvement of CD4(+) T cells in this disease and form the basis for studies to examine the nature of the stimulating antigen.

Effect of beryllium chloride on porphyrin metabolism in pregnant mice administered by subcutaneous injection.

The effect of beryllium (Be) compounds on porphyrins was investigated in pregnant mice. The blood protoporphyrin (Proto) and zinc protoporphyrin (Zn Proto) concentrations were increased in pregnancy. Regardless of pregnancy or nonpregnancy, the Proto concentration was decreased after Be injection. Delta-aminolevulinic acid dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D) activities in blood were significantly elevated in the pregnant untreated (Con-pregnant) group, compared to the nonpregnant mice untreated (Con-nonpregnant) and nonpregnant mice treated with Be (Be-nonpregnant) groups. The blood ALA-D activity of the pregnant mice treated with Be (Be-pregnant group) tended to decrease, compared to Con-pregnant group. The blood PBG-D activity in the Be-pregnant group was significantly lower compared with that of the Con-pregnant group. The ALA-D and PBG-D activities in the spleen were also significantly elevated in the Con-pregnant group, compared to nonpregnant groups. However, it was noted that these values in the Be-pregnant group were almost the same as that of the Con-nonpregnant group and were significantly lower than that in the Con-pregnant group. The elevation of ALA-D and PBG-D activities in the blood and spleen, which play a role in the hematopoietic function of mice, was observed in the Con-pregnant mice compared to the nonpregnant mice. However, the phenomenon was not observed in the Be-pregnant mice, it suggesting that Be suppressed the pregnancy-induced increase in hematopoietic function.

Chronic granulomatous pneumonia and lymphocytic responses induced by inhaled beryllium metal in A/J and C3H/HeJ mice.

Inhalation of beryllium (Be) has been associated with 2 syndromes: an acute chemical pneumonitis and a granulomatous lung disease known as chronic beryllium disease (CBD). Key to the pathogenesis of CBD is a delayed-type hypersensitivity reaction, in which Be most likely functions as a hapten and acts as a Class II-restricted antigen, stimulating local proliferation and accumulation in the lung of Be-specific CD4+ T cells. The purpose of this study was to establish a mouse model of CBD using the inhalation route of exposure. A/J (H-2a haplotype) and C3H/HeJ (H-2a) mice were exposed once for 90 min in nose-only exposure tubes to aerosols of Be metal. Six mo later, lung histopathologic responses were assessed. Further analyses defined the phenotypic profile of lymphocytes in pulmonary lesions and evaluated proliferation of lymphocytes in situ and in response to Be in vitro. Responses were similar in both strains of mice. The lungs of all Be-exposed mice had interstitial compact aggregates of lymphocytes, and granulomatous pneumonia characterized by vacuolated macrophages and giant cells in alveoli, neutrophils in alveoli and alveolar septa, multifocal interstitial granulomas, and interstitial infiltrates of lymphocytes, plasma cells, monocytes, and macrophages. Most Be-exposed mice had minimal to mild interstitial fibrosis. The majority of lymphocytes in interstitial infiltrates and in microgranulomas were CD4+ T cells. Interstitial compact aggregates of lymphocytes contained B cells centrally and CD4+ cells peripherally. Lymphocyte labeling indices, used to assess proliferation in situ, were significantly greater within microgranulomas compared to compact lymphocytic aggregates. Lymphocyte stimulation indices in response to BeSO4 in vitro were not positive in blood, spleen, or tracheobronchial lymph node samples. Be-specific immune responses and nonspecific inflammatory responses to toxic and foreign-body properties of Be may have contributed to the histopathology in both strains of mice. The interstitial mononuclear cell infiltrates, presence of microgranulomas, multinucleated foreign-body and Langhans' giant cells, interstitial fibrosis, and CD4+ T-cell predominance with local proliferation are features similar to CBD in humans. The chronic lung disease induced in these mice by inhaled Be can be used to investigate the importance of variables such as dose, exposure pattern, and physicochemical form of Be in producing this disease.

Patch testing with beryllium alloy samples in guinea pigs.

An experimental study was conducted in guinea pigs for the predictive assessment of the beryllium alloy hazard in occupational exposure of the skin to beryllium compounds. Guinea pigs were sensitized to beryllium sulfate according to the maximized Magnusson and Kligman test, and challenged with beryllium alloys and metallic copper, beryllium and aluminum samples. Results showed a delayed skin hypersensitivity reaction in 30 to 60% of pre-sensitized guinea pigs challenged with copper-beryllium alloys and aluminum-beryllium alloy. An inflammatory follicular reaction was induced by copper in both controls and pre-sensitized guinea pigs.

[The changes of complement activities in sera of mice after subcutaneous administration of beryllium chloride].

We studied changes of the complement pathway activities and the content of C3 in sera of mice, administered BeCl2 (containing 5 micrograms of Be per mouse) or CuCl2 (containing 5 micrograms of Cu per mouse) by a single subcutaneous injection. The value of the classical complement pathway activity (CH50) of the Be group 3 days after administration was significantly higher than that of the control group (P < 0.001). It was significantly lower than in the control group after 7 days (P < 0.001). On the other hand, the CH50 value of the Cu group 3 hr after administration tended to increase, however, it was significantly lower than in the control group after 7 days (P < 0.01). The change of the alternative complement pathway activity (ACH50) value of the Be group was similar to the change of the CH50 value of the group. The ACH50 value of the Cu group 3 days after administration tended to increase but it was the same as the ACH50 value of the control group after 7 days. The C3 contents of both the Be and Cu groups 3 days after administration were significantly higher than in the control group (P < 0.001). The aspartate aminotransferase (AST) activity of the Be group 7 days after administration was significantly higher than that of the control group (P < 0.01). By contrast, AST activity of the Cu group 3 hr after administration was significantly higher than in the control group (P < 0.05). The value of the alanine aminotransferase (ALT) activity of the Be group was low (P < 0.01), but that of the Cu group was high (P < 0.05), 3 hr after administration. These values of both groups after 7 days, however, were significantly higher than in the control group (P < 0.05). The AST/ALT ratio in mice was very high at 3 hr, and it remained high by 7 days after Be injection. On the other hand, the ratio of the Cu group was almost constant for 7 days after Cu injection. Thus, these values changed with relative expedition after Be injection. Therefore, we confirmed that measurements of complement activities and the content of C3 were valuable indices for assaying acute effects of Be on mice.

Distribution of radioisotopic beryllium in mice after administration by various routes of injection.

A 7BeCl2 solution containing 0.5 micrograms Be per mouse was injected subcutaneously, intraperitoneally, intramuscularly, intrathoracically, and intravenously, and distribution was observed for periods up to 1 wk. 7Be was excreted more rapidly following intravenous injection than by the other routes of injection. The amount of Be found in the liver or the spleen was substantial at 1 d after intraperitoneal injection. It increased more in the spleen at 7 d after either intraperitoneal or intrathoracic injection. On the other hand, the amounts of Be stayed almost constant in the kidneys, by the various routes of injection. When injected intrathoracically, the amounts of Be in the heart and the lung were greater than when administered by the other routes of injection. The amounts of Be in the femurs of mice administered by these routes of injection, except with intravenous injection, were greater than in the other organs. The percentage of 7Be in the mineralized bone was 90% of that of 7Be in the femurs when injected intraperitoneally or intrathoracically. However, the ratio of Be in the mineralized bone to that in the bone marrow was 3 to 2. Beryllium had thus a closer affinity for the femurs than for the other organs investigated, with the different modes of administration used. The amount of Be in the entire skeleton was estimated to be substantial. Within the limitations of 1 wk of exposure, the skeleton would appear to be a critical organ. This would suggest that osteosarcomas may occur following administration of Be to laboratory animals for a long-term period.

Beryllium-induced lung disease in the dog following two exposures to BeO.

We have shown previously that dogs exposed once to aerosols of beryllium oxide (BeO) calcined at 500 or 1000 degrees C developed granulomatous lung lesions as well as Be-specific immune responses in the blood and lung. In this report, we investigate the immunopathologic consequences of exposing dogs twice to aerosols of BeO. Dogs previously exposed to aerosols of 500 or 1000 degrees C calcined BeO to achieve an initial lung burden (ILB) of either 50 or 17 micrograms/kg body wt were exposed a second time to BeO calcined at 500 degrees C, 2.5 years after the first exposure, to achieve an ILB of about 50 micrograms/kg body wt. Immune responses of peripheral blood and lung lymphocytes were measured at 0, 14, 30, 60, 90, 120, 150, 165, 180, and 210 days postexposure (dpe), and dogs were euthanized at 210 dpe. Be-specific immune responses occurred in blood at 30 dpe and again at 150 to 210 dpe. Only sporadic positive responses were seen among lung lymphocytes when cells were cultured in 10% fetal bovine serum. In contrast, samples collected at 165, 180, and 210 dpe and incubated with 10% dog serum showed a large number of positive responses in both blood and lung. Histologic lesions were characterized by perivascular and interstitial infiltrates of lymphocytes and macrophages with progression to patchy granulomatous pneumonia accompanied by focal septal fibrosis. We conclude that Be-induced granulomatous and fibrotic lung lesions are accompanied by Be-specific immune responses within the lung but these changes do not appear to be cumulative if enough time has elapsed between exposures.

Overview of pulmonary alveolar macrophage renewal in normal rats and during different pathological processes.

We report experimental results on pulmonary alveolar macrophage (PAM) renewal in healthy rats and in rats treated with particles introduced in the lungs. Morphometric studies showed that the lungs of normal rats of the strain used in our study contain 20 x 10(6) PAM, 50 x 10(6) monocytes in alveolar capillaries, and about 3 x 10(5) interstitial macrophages. Pulse labeling with a tritiated thymidine (3HT) gave a labeling index of 0.4% for the monocytes, of which a few could be observed in mitosis within alveolar capillaries. These monocytes are likely to be the PAM precursors. The daily input (greater than 4%) by PAM proliferation exceeds PAM loss by migration to the upper respiratory tract (2.5%). The life span of PAM was measured by sequential counting of lavaged cells after labeling with [125I]iododeoxyuridine instilled intratracheally. The pulmonary lavage procedure used allowed us to recover at least 80% of the whole PAM population. A daily loss of PAM of 8-9% was measured, of which loss by death in the endoalveolar compartment was estimated at 5-6%. During the pathological processes studied, several parameters of PAM renewal were shown to be modified. PAM migration to the upper respiratory tract was frequently inhibited, PAM cytotoxicity was observed, and PAM proliferation increased in some cases and decreased in others. Under most of the pathological conditions investigated, the renewal of endoalveolar macrophages appeared quite different from that in normal rats, and direct blood monocyte migration to the endoalveolar compartment became a major component of PAM renewal.

Induction of sperm head abnormalities by incorporated radionuclides: dependence on subcellular distribution, type of radiation, dose rate, and presence of radioprotectors.

In contrast to the biological effects caused by exposure to external beams of radiation, the effects of tissue-incorporated radionuclides are highly dependent on the type of radiation emitted and on their distribution at the macroscopic, microscopic, and subcellular levels, which are in turn determined by the chemical nature of the radionuclides administered. Induction of abnormalities of sperm heads in mice is investigated in this work after the injection of a variety of radiochemicals including alpha emitters. When the initial slopes of the dose-response curves are used to compare the relative biological effectiveness (RBE) of different radiocompounds, the alpha particles emitted in the decay of 210Po are more effective than Auger electrons emitted by 125I incorporated in the DNA of the spermatogonial cells, and both emissions are more effective than X rays. It is also shown that the Auger emitters (125I, 111In) distributed in the cell nucleus are more efficient in producing abnormalities than the same radionuclides localized in the cytoplasm. These findings are consistent with our earlier observations, where spermatogonial cell survival is assayed as a function of the testicular absorbed dose. Further, chronic irradiation of testis with gamma rays from intratesticularly administered 7Be is about three times more effective in causing abnormalities than a single acute exposure to 120-kVp X rays. The resulting RBE values correlate well with our data on sperm head survival with the same radiocompounds. Finally, the radioprotector cysteamine, when administered in small, nontoxic amounts, significantly reduces the incidence of sperm abnormalities from alpha-particle radiation as well as emissions from 125I incorporated into DNA, the dose reduction factors being 10 and 14, respectively.