Pathological developments mediated by cyclophosphamide in rats infected with Trypanosoma lewisi.

Trypanosoma lewisi is an obligatory, flagellated parasite of the rat. Despite the fact that naturally the rats overcome the disease, a lethal infection can be induced by the administration of an immunosuppressive agent, i.e. cyclophosphamide (Cy). In the Cy treated infected rats (CyI) the severity of the trypanosome infection was demonstrated in the internal organs, in the following order: lungs>liver>heart>spleen>kidney. The parasites were not detected in the brain. The accumulation of the parasites in the lungs led to the development of hemorrhagic inflammatory foci. The rupture of blood vessels was accompanied by lymphocyte infiltrations into the damaged tissues and multiple foci of edema around the blood vessels. In most cases the lungs were dark brown in color due to intra-alveolar hemorrhages. The spleen of the CyI rats showed general deformation of the tissue's architecture, migration of macrophages and cell depletion due to the Cy action. The liver showed inflammatory hemorrhagic foci associated with massive destruction of the parenchyma. In spite of the heavy parasitemia (>50%) developed in the CyI rats the brain remained free of parasites, which might explain the non-virulent character of this parasite compared to the African trypanosomes.

Measles virus: evidence of an association with Hodgkin's disease.

The quest for an infectious agent that may account for cases of Hodgkin's disease (HD) especially in young adults has proven vain until lately. We have recently reported findings that suggested the presence of measles virus (MV) antigens and MV RNA in the tissues of patients with HD. Support for an association between MV and HD has been provided by recent epidemiological findings relating the occurrence of HD to exposure to measles in pregnancy and the perinatal period. We now present further evidence of this putative association based on immunohistochemical, reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridisation studies (ISH) on HD tissues. Biopsies from 82 (54.3%) of our cohort of 154 patients showed a positive immunostain with at least two of the anti-measles antibodies used. Latent membrane protein-1 immunostaining for Epstein-Barr virus was positive in 46 (31.1%) of the patients examined. Reverse transcriptase-PCR and ISH for measles RNA were positive in seven and 10 of 28 patients, respectively. Preliminary clinicopathological associations between MV and HD are noted in this study, but no causal relationship can be claimed at this stage.

Immunohistochemical staining of IL-1 alpha and IL-1 receptor antagonist but not IL-1 beta in cultures of sertoli cells.

The interleukin-1 (IL-1) system has been suggested to be involved in the cell cell cross talk within the testis. To identify a testicular cell source of IL-1 alpha, IL-1 beta and IL-1 receptor antagonist (IL-1ra), immature mouse Sertoli cells were isolated, purified, cultured and examined for the cellular compartment localization of these cytokines by immunohistochemical staining. Our results show that both Germ cells and Sertoli cells in unpurified Sertoli cell cultures (before hypotonic shock) and purified culture of Sertoli cells (after hypotonic shock) were stained for IL-1 alpha. The levels of this cytokine were increased in Sertoli cells when the purified cultures were stimulated with lipopolysaccharide (LPS) (5 microg/mL). However, we could not identify a positive staining for IL-1 beta when Sertoli cell cultures were stained for this cytokine, even after stimulation with various concentrations of LPS (0.1-10 microg/mL). On the other hand, immunohistochemical staining of isolated Sertoli cells without treatment with hypotonic shock (cultures containing Sertoli cells and Germ cells) for IL-1ra showed constitutive positive staining of both cell types (Sertoli cells and Germ cells). Our results, using immunohistochemical staining, may indicate the different expression of IL-1 alpha, IL-1 beta and IL-1ra in Sertoli cells. These results may suggest the involvement of IL-1 system in the autocrine and paracrine regulation of testicular cell functions.

Neoangiogenesis in squamous cell carcinoma of the larynx - biological and prognostic associations.

Tumor angiogenesis has been related to tumor growth and an increased probability of metastatic spread. Previous studies have led to conflicting views regarding the prognostic significance of angiogenesis in squamous cell carcinoma of the head and neck. To evaluate the role of tumor angiogenesis in the biology of squamous cell carcinoma of the larynx, we quantified the microvascular network in 59 primary laryngeal carcinomas and looked for an association with outcome. Microvessels were stained immunohistochemically using antibodies for factor VIII-related antigen and the antibody JC70 (CD-31). In each case, microvessels were counted in three fields at x200 magnification, in areas of most intense neovascularization. We found a significantly higher number of microvessels in tumors showing deeper levels of invasion.

Apoptosis (programmed cell death) in colonic cells: from normal to transformed stage.

We determined apoptosis in whole rat colonic tissue and in isolated colonocytes from the various rat crypt regions in preneoplastic stages up to frank neoplasia following administration of the procarcinogen, dimethylhydrazine (DMH). Apoptotic cells were determined by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL)-method, by evaluating sections stained with hematoxylin and eosin, and caspase-1 immunostaining. Apoptotic cells in whole colonic tissue from untreated rats were confined to the upper crypt while, in DMH-treated rats apoptotic and caspase-1 positive cells were located in the crypt proliferative regions. Numerous apoptotic and caspase-1-positive cells were found in sections from early tumors while in the delayed tumors, apoptotic-positive cells were absent and number of caspase-1-positive cells was negligible. A marked reduction in the apoptotic index along the crypt was observed in isolated transformed colonic cells, this was not the case for caspase-1-positive cells. We conclude that: (i) in colorectal tumors at progressive stage apoptosis is altered, (ii) the mechanistic alteration in apoptosis may be located between caspase-1-protease activity and the fragmentation process of DNA.

Differential expression of sialyl and non-sialyl-CD15 antigens on Hodgkin-Reed-Sternberg cells: significance in Hodgkin's disease.

CD15 expression has been used for years to confirm the diagnosis of Hodgkin's disease (HD). Little is, however, known on the relevance of the CD15 antigen to the pathobiology of the disease and there is conflicting evidence as to the prognostic value of its expression. To investigate the significance of the differential expression of CD15 in Hodgkin's disease, a retrospective study of 102 patients with "classical" Hodgkin's disease was performed. Immunohistochemical studies were carried out using antibodies against two types of CD15: non-sialylated CD15 (LeuM1 and 80H5) and sialylated CD15 (FH6 and CSLEX1). Cases that were negative for non-sialylated CD15 or positive for the sialylated variant were stained again following neuraminidase pretreatment. The cohort included 27 patients in whom sequential biopsies were available. Both CD15 expression in its non-sialylated form and absence of sialyl-CD15 expression correlate with a favorable outcome. Subsequent biopsies show a preferential expression of sialyl-CD15, notably in bone marrow metastases. Our findings suggest that, in the progression of HD towards a widely disseminated disease, the LewisX moiety of the CD15 antigen on the tumor cells acquires a sialyl-group. This change may confer on the tumor cells the capacity to metastasize.

Interleukin-1 receptor antagonist is produced by sertoli cells in vitro.

The interleukin-1 (IL-1) system has been suggested to be involved in the cell-to-cell cross-talk within the testis. To identify a testicular cell source of IL-1 receptor antagonist (IL-1ra), mouse Sertoli cells were isolated, purified, cultured, and examined for IL-1ra. Our investigation revealed that Sertoli cells produce large amounts of immunoreactive IL-1ra under basal culture conditions, as examined by enzyme-linked immunosorbent assays. Its expression can be induced, showing maximum concentrations after 8 h of stimulation. Lipopolysaccharide, as well as IL-1alpha and -beta, were found to stimulate IL-1ra production in Sertoli cells. FSH is capable to induce IL-1ra production in Sertoli cells in a dose-dependent manner. Immunocytochemical staining confirmed the presence of IL-1ra in the cytoplasma of Sertoli cells. The presence of IL-1ra messenger RNA was demonstrated by RT-PCR analysis. Our results may help to better evaluate the IL-1 activity in the testis and may indicate the involvement of IL-1ra in the autocrine and paracrine regulation of testicular cell function.

Induction of interleukin-1alpha production in murine Sertoli cells by interleukin-1.

In the present study we examined the involvement of interleukin (IL)-1alpha, -1beta, FSH, and lipopolysaccharide (LPS) in the regulation of IL-1alpha and -1beta production by Sertoli cells under in vitro conditions. Sertoli cell cultures from immature mice produced constitutively basal levels of intracellular IL-1alpha. Stimulation of Sertoli cell cultures with LPS (5 microgram/ml) resulted in a maximal production of intracellular IL-1alpha 2 h after the stimulation. Thereafter, these levels decreased but remained significantly higher within 24 h after stimulation than those in control cultures. The effect of LPS on IL-1alpha production was dose dependent. FSH did not show any effect on intracellular IL-1alpha production by Sertoli cells. IL-1alpha could not be detected in supernatants of unstimulated or stimulated Sertoli cell cultures. Sertoli cell cultures stimulated with recombinant IL-1alpha induced optimal intracellular levels of IL-1alpha within 2 h of stimulation. These levels remained high 24 h after stimulation. However, stimulation of Sertoli cell cultures with IL-1beta induced a peak of IL-1alpha production 8 h after stimulation. These levels decreased 24 h after the stimulation but were still found to be significantly higher than those in control cultures. The addition of IL-1 receptor antagonist (IL-1ra) to Sertoli cell cultures did not significantly alter their capacity to produce IL-1alpha. However, the stimulatory effects of recombinant IL-1alpha on IL-1alpha production by Sertoli cell cultures were reversed by the concomitant addition of recombinant IL-1ra. No immunoreactive IL-1beta could be detected in lysates or conditioned media of immature murine Sertoli cells under any of the stimulatory conditions outlined. Our results may suggest the involvement of physiological (IL-1) and pathophysiological factors (LPS) in the regulation of spermatogenesis and spermiogenesis processes and male fertility.

Apoptotic index as a prognostic factor in Hodgkin's disease.

Hodgkin's disease (HD) is an unusual malignant neoplasm, mainly because of the rarity of tumor cells in the diseased tissues, but also due to a relatively favorable response to treatment. In a previous study, we have shown a variable degree of apoptosis in lymph nodes from HD patients. We now looked for clinicopathological correlations of apoptosis with special emphasis on the prognosis in this disease. A retrospective study of 92 patients was carried out, using in situ end labelling of DNA fragments and an apoptosis detection kit. An apoptotic index (Al) was calculated in each case, as the percentage of apoptotic Hodgkin-Reed-Sternberg cells out of the total number of tumor cells in 10 selected high power fields. An association between a high Al and advanced stages was noted. A Kaplan-Meier analysis showed a negative correlation between Al and survival (p=0.05). In a multivariable analysis adjusting for Ann Arbor stage, a high Al carried a 3.27 fold risk of dying of HD (OR=3.27; Cl=0.89-11.94). However, in our limited cohort of HD patients, Al was not an independent prognostic factor. The results of this study confirm the important role played by apoptosis in HD and suggest that the apoptotic index is probably a negative prognostic marker in this disease. Its assessment in patients with HD may provide a new, important clinical tool.

Extensive apoptotic death of rat colonic cells deprived of crypt habitat.

Apoptosis in cells of different lineages is restrained by survival signals which depend upon cell-to-cell communication. The aim of this study was to determine whether colonic cells deprived of crypt ambient are doomed to die prior to their normal chronological demise. Apoptosis was studied in rat whole colonic tissue, in isolated intact crypts, and in colonic cell populations collected from the crypt axis at different stages of proliferation and differentiation. In a number of experiments, cell harvest was performed in the presence of either a tetrapeptide (YVAD-CMK) inhibitor of interleukin-1beta-converting enzyme (ICE), or tyrphostin A25, a protein tyrosine kinase inhibitor, or sodium-orthovanadate, a phosphatase inhibitor. DNA fragmentation was assessed by electrophoretic and nonisotopic-labeling procedures. The ultrastructure of colonic tissue specimens and isolated cells was examined by transmission electron microscopy. Apoptosis in whole colonic tissue and in isolated crypts was confined predominantly to cells resident in the upper crypt regions. In contrast, extensive apoptotic death was observed in isolated colonic cells, irrespective of their developmental stage and positional hierarchy within the crypt continuum at harvest time. An apoptotic gradient, however, was evident. Exposure to YVAD-CMK resulted in a marked decrease in the number of apoptotic cells. Treatment with tyrphostin A25 caused a sharp rise in the apoptotic index; conversely, vanadate significantly impeded apoptosis. Cumulatively, these results indicate that disordered intercellular communication provokes unscheduled ICE-mediated apoptosis of colonocytes, and that local signals along the crypt continuum control both the reprieve from death and the timely demise of distinct colonic cell populations. Attenuation of tyrosine phosphorylation may be a contributory event in the acquisition of the apoptotic phenotype.

Tumor necrosis factor-alpha and interleukin-6 are differently expressed by fresh human cancerous ovarian tissue and primary cell lines.

The expression levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were evaluated in normal and cancerous ovarian tissue and primary cell lines (PCL). Seven normal and 10 cancerous, formalin-fixed ovarian samples were examined for TNF-alpha and IL-6 expression by immunohistochemical staining using polyclonal rabbit anti-human TNF-alpha and IL-6 antibodies. Fresh normal and cancerous specimens were also examined for TNF-alpha and IL-6 secretion by bioassay and immunoassay prior to and following in vitro stimulation with lipopolysaccharide (LPS). The levels of IL-6 and TNF-alpha were higher in cancerous tissues than in normal specimens. In vitro stimulation of normal and cancerous ovarian tissues and PCL revealed their capacity to secrete IL-6. Cancerous tissue and PCL secreted higher levels than normal tissue and PCL. Stimulation of both groups with LPS increased their capacity to secrete IL-6. Optimal secretion of IL-6 by the cancerous tissue was observed after 72 hours with or without LPS (10 microg/ml). Normal tissue secreted maximal levels of IL-6 after 96 hours with or without LPS. PCL from normal ovarian tissue secreted IL-6 constitutively and optimal expression was detected after 96 hours. Carcinoma PCL from cancerous ovarian tissue demonstrated optimal secretion of IL-6 after 24 hours. Stimulation of both types of cells with LPS, IL-1 or TNF-alpha increased their capacity to secrete IL-6. TNF-alpha activity was detected in vitro only in supernatants of ovarian cancerous tissue and only after LPS stimulation; optimal levels were detected after 48 hours and 1 microg/ml LPS. Our results indicate that IL-6 and TNF-alpha are expressed in cancerous ovarian tissue at a higher level than in normal ovarian tissues. Carcinoma cells of ovarian tissues are the main cellular source of these cytokines. The conditions controlling the secretion of these cytokines, under in vitro conditions, are different in cancerous and normal ovarian tissues.

Distinct patterns of expression of interleukin-1 alpha and beta by normal and cancerous human ovarian tissues.

Immunohistochemical staining of normal and cancerous ovarian tissues has demonstrated that both IL-1 alpha and IL-1 beta are more strongly expressed in cancerous than in normal tissues and are secreted mainly by epithelial cells. We have shown by bioassay and immunoassay that cancerous, but not normal ovarian tissues constitutively secrete IL-1 in vitro. Activation of cancerous ovarian tissues by lipopolysaccharide (LPS) increased its capacity to secrete IL-1. Normal ovarian tissues secreted low amounts of IL-1 only after prolonged stimulation (72-96 h) by high doses of LPS (10-100 micrograms/ml). On the other hand, constitutive IL-1 was detected in homogenates of normal ovarian tissues and stimulation by LPS increased its capacity to produce IL-1. IL-1 beta was the main type of IL-1 secreted by cancerous ovarian tissues. IL-1 alpha was detected at lower levels. In contrast, in normal tissues similar amounts of both IL-1 alpha and IL-1 beta were detected in the supernatants. The levels of both types of IL-1, and also the bioactivity of IL-1 were significantly higher in cancerous than in normal ovarian tissues. Established primary cell lines from normal ovarian tissues did not secrete IL-1 into supernatants but did express it at very low levels. Stimulation with LPS did not affect the capacity of these cell lines to secrete IL-1 but it increased their capacity to express it. In contrast, primary established epithelial cell lines from cancerous ovarian tissues did secrete and express high levels of IL-1 and these levels were increased under stimulation with LPS. Cancerous ovarian tissues did not only secrete higher levels of both IL-1 alpha and beta than normal ovarian tissues, but also the mechanism controlling the secretion of these factors in cancerous ovarian tissues seemed to be different from that found in normal ovarian tissues. Our results suggest that paracrine/autocrine factors may be involved in the regulation of both types of IL-1 secreted by ovarian tissues. These cytokines may play a role in regulating the physiological, pathophysiological and oncogenic processes of the ovary.

Association of the Epstein-Barr virus with Hodgkin's disease in Southern Israel.

Epstein-Barr virus (EBV) has been frequently documented in the putative neoplastic Hodgkin-Reed-Sternberg (HRS) cells, in lymph nodes from patients with Hodgkin's disease (HD). This association varies in different geographic areas and between industrialized and developing countries, as does the epidemiological pattern of the disease. In the present study of 106 cases of HD from the Soroka Medical Center in Beer-Sheva, which serves as the only hospital for most of the southern part of Israel, we found an association with EBV expression in only 30% of the patients; 45% of mixed cellularity (MC) cases compared with 21% of nodular sclerosis (NS) cases were positive for EBV. The number of patients in the 0-14-year-old age group was limited; however, 8 of these II children were EBV positive. This low association rate of HD with the presence of EBV sequences is probably related to the small number of children in our series. A low proportion of EBV-associated disease in older adults may be contributory. Other factors may be involved.

A comparison of distinct modes of tumor cell death in Hodgkin's disease using morphology and in situ DNA fragmentation.

The study examined the morphology and frequency of cell death occurring spontaneously in lymph nodes from patients with Hodgkin's disease. In addition to necrosis, which was infrequent and usually in patches, we document two cell types showing features of individual cell death: mummy cells end apoptotic cells. Mummy cells present no evidence of DNA fragmentation, but show electron microscopic features of "dark cells." Apoptotic Hodgkin-Reed-Sternberg cells are found frequently and are easier to demonstrate by in situ and labeling of fragmented DNA than by light microscopy only. In many cases phagocytosis of apoptotic cells is also documented. The significance of these findings to the limited number of Hodgkin-Reed-Sternberg cells in most cases of Hodgkin's disease is discussed.

Frequent expression of the cell death-inducing gene Bax in Reed-Sternberg cells of Hodgkin's disease.

The expression of a cell death-inducing gene, Bax, was investigated in 52 cases of Hodgkin's disease in parallel with Epstein-Barr virus and was compared with the immunodetection of other apoptosis-regulating proteins, Mcl-1, Bcl-2, and Bcl-x. Bax immunostaining was found in 92% of the cases, among them 28% with a strong signal in more than 75% of the Reed-Sternberg cells. Mcl-1 was positive in 80% of the cases, whereas Bcl-2 and Bcl-x were found in 53% and 88% of the cases, respectively. Of 48 (89%) Bax-positive tumors, 43 were found to express apoptosis-inhibiting proteins such as Mcl-1 or Bcl-2. With the exception of 1 case, all Bax-positive tumors also expressed either Bcl-2, Bcl-x, Mcl-1, or combinations of these anti-apoptotic proteins. No correlation was found between Bax expression and the presence of apoptotic cells as detected by morphology and the in situ 3' OH-DNA end-labeling technique. Our findings show that the apoptosis-inducing gene Bax expression is frequently expressed in Hodgkin's disease, providing a potential explanation for the good chemoresponses generally obtained for patients with this neoplastic disorder.

Interleukin-1 and tumor necrosis factor-alpha in the Reed-Sternberg cells of Hodgkin's disease. Correlation with clinical and morphological "inflammatory" features.

We examined paraffin sections for the expression of interleukin-1 alpha, interleukin-1 beta and tumor necrosis factor-alpha, in 40 cases of Hodgkin's disease. Our purpose was to study the role of these cytokines in the "inflammatory" histological features and "B" symptoms in this disease. Immunohistochemistry with the avidin-biotin-peroxidase complex method was used. The findings were compared with those of 20 cases of non-Hodgkin's lymphomas and of 20 non-neoplastic lymphadenopathies. Evidence for EBV infection and myc and ras oncoproteins expression was also studied in these patients, but no correlation between any of these features and cytokine expression was found. We found a significant correlation between the expression of interleukin-1 beta and several "inflammatory" histological features, as well as between the expression of tumor necrosis factor-alpha and B symptoms and tumor bulk. The differential correlations between these major pro-inflammatory cytokines expression and the "inflammatory" manifestations in Hodgkin's disease are remarkable, considering the complexity of the cytokines composing the cytokine network involved in this disease.

Expression of c-myc and c-ras oncogenes in the neoplastic and non-neoplastic cells of Hodgkin's disease.

The oncogenes c-myc and c-ras are known to elicit a cooperative tumorigenicity. In this study we investigated their role in the pathogenesis of Hodgkin's disease. The expression of these oncogenes was determined in Hodgkin's disease patients by avidin-biotin peroxidase complex immunohistochemical staining and was compared to their expression in patients with non-Hodgkin's lymphomas and inflammatory reactive lymph nodes. Of 29 examined patients with different histological types of Hodgkin's disease, 21 (72.4%) showed an elevated expression of c-myc and 28 (96.5%) of c-ras. Although this expression was marked especially in the neoplastic Reed-Sternberg cells, it was also noted in the numerous reactive cells present in the involved lymph nodes. By contrast, a much lower frequency of increased expression of these oncogenes was recorded in 19 patients with different grades of non-Hodgkin's lymphoma and in 29 patients with inflammatory reactive lymph nodes. The elevated expression of c-myc and c-ras in the neoplastic Reed-Sternberg cells may reflect an oncogenic event that directly activates these genes. However, their increased expression in the surrounding non-neoplastic cells probably results from signal transduction induced by certain growth-promoting factors possibly released by the Reed-Sternberg cells and that act paracrinally to stimulate the proliferation of the neighboring cells. Furthermore, the continuous c-ras elevation may impair the normal cell cycle control and thereby promote mutagenesis and overt malignancy.

Phosphotyrosine, p62 c-myc and p21 c-Ha-ras proteins in colonic epithelium of normal and dimethylhydrazine-treated rats: an immunohistochemical analysis.

In the present study we used monoclonal antibodies to investigate the expression of phosphotyrosine, c-myc and c-Ha-ras proteins along the crypt continuum of normal and transformed rat colon tissue. Colon cancer was induced by administration of dimethylhydrazine. Particular attention was focused on the immunohistochemical pattern of murine colon mucosa during preneoplastic stages so as to permit the identification of putative changes in the expression/location of the oncoproteins prior to frank neoplasia. The immunohistochemical analysis of tyrosinephosphorylated proteins in the normal rat indicated that positive staining was mostly restricted to the lower colonic crypt zones. The carcinogenetic insult altered the magnitude and positional profile of phosphotyrosine along the colon crypt axis during the preneoplastic period. An intense positive reaction was observed in the upper crypt regions. Four weeks following the last DHM administration, viz. before tumor appearance, positive staining was evident in invasive adenocarcinoma tissue. In contrast to phosphotyrosine, the feeble c-myc immunohistochemical staining of normal rat colonic did not exhibit a focal topology. However, following DMH administration and prior to frank neoplasia, a substantial increase in the staining intensity for c-myc was noted, confined mostly to the supranuclear region of luminal cells. Invasive adenocarcinomas displayed intense cytoplasmic c-myc immunoreactivity. p21 c-Ha-ras expression and location along the colon crypt axis showed a different pattern when compared to p62 c-myc and phosphotyrosine. The p21 c-Ha-ras protein was prominently expressed in surface epithelium of normal and DMH-treated rats. Midcrypt colonocytes exhibited moderate p21 ras staining; in contrast, proliferating colonic cells resident in the lower crypt regions were consistently negative. These results suggest that c-Ha-ras gene product plays an important contributory role in determining the differentiated phenotype of the colonic cell.

Pulmonary mechanics in dogs given different doses of kerosene intratracheally.

Kerosene was instilled intratracheally into mongrel dogs of either sex weighing 10 to 15 kg and anesthetized intravenously with sodium pentobarbital (25 mg/kg). Two different doses were used: 0.3 and 0.06 ml/kg. Pulmonary mechanics, including pressure-volume (P-V) curve, thoracic gas volume (Vtg), total lung capacity (TLC), total pulmonary resistance (RL), and chord compliance (CL) were measured by using a whole body plethysmograph, before and at various time intervals during the 2 wk after instillation. Histologic studies were also performed. In the high-dose (0.3 ml/kg) kerosene experiments there were significant decreases in Vtg, TLC, and CL values by 24 h, which returned to control values at 1 wk after kerosene instillation. The RL and CL normalized for TLC did not change. In contrast, in the dogs receiving the low dose (0.06 ml/kg), there was no significant change in any of these parameters at 24 h. Histologic examination revealed an early exudative phase consisting of exudation of macrophages, red cells, and edema (at 1 and at 24 h), and a later phase consisting of proliferative bronchiolitis (at 1 and at 2 wk). Animals receiving the low dose revealed the same pattern as those receiving the high dose at 24 h, but changes were less extensive. We conclude (1) that kerosene-induced lung injury causes loss of terminal air spaces at both low and high doses, and (2) that the shift in the P-V curve is dose dependent. We hypothesize that kerosene causes two types of physiologic lesions. In areas in which terminal air spaces remained open, an increase in compliance occurred, whereas in areas in which intraalveolar exudation occurred there was "drop-out" of lung units. The final P-V curve was determined by the relative proportions of these two types of areas.

Chromosomal aberrations in occupation-associated progressive systemic sclerosis.

An occupational association between progressive systemic sclerosis (PSS) and workers in the goldmining industry in South Africa was first documented in 1957. We investigated the chromosomes of 18 goldminers suspected to be suffering from PSS. Eight patients were classified as definite cases of PSS, and a highly significant increase in unstable (Cu) cells and random aneuploidy was found in this group compared with control subjects (P < 0,001). Ten patients had some of the features of the disease, and in this group there was a significant increase in the number of Cu cells ( P < 0,05) and a highly significant increase in the number of aneuploid cells (P < 0,001). There was a significant increase in the number of sister chromatid exchanges per cell in the 6 patients screened. These findings are similar to those reported in PSS sufferers who have not had occupational exposure.