Molecular mechanisms for bromotrichloromethane cytotoxicity in isolated rat hepatocytes

1. Bromotrichloromethane added to isolated rat hepatocytes resulted in increased cell death as determined by trypan blue uptake. Toxicity increased in a concentration-dependent fashion between 2.0-5.0 M bromotrichloromethane. 2. Lipid peroxidation (malondialdehyde) increased in a time-dependent fashion but in contrast to toxicity reached a maximum level at 2.0 mM bromotrichloromethane. 3. Hypoxia increased the toxicity of bromotrichloromethane three-fold but only decreased the amount of lipid peroxidation to a small degree. 4. In spite of this poor correlation between toxicity and lipid peroxidation, the antioxidant butylated hydroxyanisole and the iron chelator desferal protected the cells from toxicity under both aerobic and hypoxic conditions and prevented lipid peroxidation. 5. During treatment with bromotrichloromethane, cellular glutathione levels slowly decreased and oxidized glutathione appeared in the media. The addition of cystine to the incubation media prevented the formation of extracellular oxidized glutathione, indicating that cellular glutathione had leaked from the cell during treatment and was oxidized in the incubation media. Although this suggested that glutathione does not play a protective role against bromotrichloromethane toxicity, diethyl maleate-pretreatment of the cells to decrease glutathione levels markedly increased bromotrichloromethane toxicity. 6. The addition of ascorbic acid to the incubation media increased bromotrichloromethane toxicity. This was attributed to the reductive activation of bromotrichloromethane in an iron and oxygen-dependent reaction. 7. It was concluded that peroxidation of essential phospholipids contributes to bromotrichloromethane-induced hepatocyte cytotoxicity.

Toxicity of nitrobenzene compounds towards isolated hepatocytes: dependence on reduction potential

1. The cytotoxicity of p-substituted nitrobenzenes towards isolated hepatocytes under aerobic or hypoxic conditions has been determined. The nitrobenzene concentration required to cause 50% cytoxicity in 2 h was a function of the one-electron reduction potential of the nitrobenzene, with the more cytotoxic compounds having the strongest electron-withdrawing substituents. 2. The effectiveness of the nitrobenzenes at causing cytotoxicity under aerobic but not hypoxic conditions was markedly increased if hepatocyte catalase was inhibited with azide. 3. Nitrobenzenes at cytotoxic concentrations induced cyanide-resistant respiration in isolated hepatocytes. Their effectiveness correlated with their cytotoxicity. 4. The rate of oxygen activation of these nitrobenzenes by ascorbate was also a function of the one-electron reduction potential. The nitro compounds with the strongest electron-withdrawing substituents were the most rapidly reduced. 5. Most nitrobenzenes were more cytotoxic under aerobic than hypoxic conditions. Ascorbate enhanced hypoxic, but not aerobic, cytotoxicity. 6. It was concluded that the cytotoxicity of different nitrobenzenes is related to their ease of reduction to nitro radical anions and nitrosobenzenes. Aerobic cytotoxicity is probably initiated by redox cycling and oxygen activation by the nitro radical anions whereas hypoxic cytotoxicity is probably initiated by the alkylation of macromolecules by nitrosobenzene metabolites.

Molecular cloning and sequencing of an Australian isolate of proviral bovine leukaemia virus DNA: comparison with other isolates

The molecular cloning and characterization of an EcoRI fragment, 8.26 kb in size, of an Australian isolate of bovine leukaemia virus (pBLV-A1) is described. This fragment includes most of the proviral genome as well as 340 bp of flanking bovine DNA sequence at the 5' end. Approximately 790 bp, including the 3' long terminal repeat, was missing from this clone. At the level of restriction enzyme mapping, this isolate could be distinguished from American, Belgian and Japanese isolates. DNA sequencing of the entire clone demonstrated some variation at the amino acid level between pBLV-A1 and the Japanese and Belgian isolates, particularly in the gag gene. In that gene there were 59 amino acid changes compared to the Japanese isolate and 24 compared to the Belgian isolate. The greater number in the case of the Japanese isolate was due to both single nucleotide changes and frameshift in a single region of the gene. This study also demonstrates that there are large tracts of amino acid sequence, particularly within the env and pol genes, that are highly conserved in different isolates. Some of these conserved sequences exist in regions containing epitopes important in virus infectivity.

Non-Hodgkin's lymphoma confined to the adrenal glands presenting with Addison's disease

We report an unusual case of Addison's disease which is unique in being diagnosed ante-mortem as being due to Non-Hodgkin's lymphoma of the adrenal glands. Both ante- and post-mortem examinations showed the lymphoma to be entirely confined to the adrenals.

Malignant transformation in a laryngeal hemangioma

Laryngeal angiosarcoma is uncommon, with only 19 previously reported cases. Malignant transformation in nonirradiated hemangiomas is extremely rare, with only five equivocal cases reported, all of which occurred in the skin. We report the first documented case of malignant transformation in a laryngeal hemangioma, and review the literature.

Accumulation of low molecular weight (bleomycin detectable) iron in bone marrow cells of rats after benzene exposure

An accumulation of low molecular weight (LMW) bleomycin detectable iron in the bone marrow was observed after administration of benzene (IP 0.5 ml/kg, daily) for 5 and 10 days in female albino rats. However, this LMW iron was not detectable in the bone marrow of rats from the control group. Studies of bone marrow fractionation showed that the maximum accumulation of this LMW iron was in the mitochondrial fraction. An increase in the activity of superoxide dismutase and lipid peroxidation was also noticed in the benzene exposed groups.

Relationship of prolactin and gonadotrophic hormones in regulation of the ovarian function

Circulating concentration of the LH, FSH, prolactin (PRL), oestradiol-17 beta (E2) and progesterone (P) in serum were investigated in women with normal cycles and proven fertility, with irregular cycles and infertility and with primary or secondary amenorrhea in order to understand the relationship of the prolactin and gonadotrophic hormens in regulation of the ovarian function. The results indicate that hyperprolactinemia inhibits the pituitary to release the midcycle LH surge in response to the positive feedback action of the elevated oestrogen at the midcycle. The elevated LH and FSH levels found in the cases of the secondary amenorrhea is the indication of the absence of the steroid negative feedback due to the ovarian failure. Prolactin does not seem to play a role on the manifestation of either primary or secondary amenorrhea.

Energy transduction in the bacterial flagellar motor. Effects of load and pH

The effect of load and pH on the relation between proton potential and flagellar rotation has been studied in cells of a smooth-swimming Streptococcus strain. The driving potential, speeds of free-swimming bacteria, and rotation rates of bacteria tethered to glass by a single flagellum were measured. The relation between rotation rate of tethered bacteria and potential was remarkably linear up to nearly -200 mV. The relation between swimming speed and potential exhibited both saturation and threshold, as previously observed in other species. The form of these relations depended on pH. The equivalence of the electrical and chemical potential components of the proton potential in enabling swimming depended on the voltage. Our observations may be most simply accommodated by a kinetic scheme that links transmembrane proton transits to a tightly coupled work cycle. The properties of this scheme were elucidated by computer simulations of the experimental plots. These simulations indicated that the protonable groups that participate in the rate limiting reactions have a fractional electrical distance between three-fourths to all of the way toward the cytoplasm with a corresponding mean proton binding affinity of 10(-7.3)-10(-7.0) M, respectively.

Differential effects of follicle-stimulating hormone and luteinizing hormone on Leydig cell function and restoration of spermatogenesis in hypophysectomized and photoinhibited Djungarian hamsters (Phodopus sungorus)

Effects of pure human follicle-stimulating hormone (hFSH) and ovine luteinizing hormone (oLH) on testicular function were investigated in long-term hypophysectomized or photoinhibited Djungarian hamsters. hFSH (5 IU) or oLH (5 micrograms) or a combination of FSH and LH (5 IU and 5 micrograms, respectively) were injected s.c. twice daily for 7 days to hypophysectomized and photoinhibited hamsters. Other photoinhibited hamsters were treated for 14 and 21 days with FSH and LH (3 IU and 3 micrograms, respectively) in a similar way. LH alone had little, if any, effect on testicular weights; FSH, when injected alone or in combination with LH (FSH/LH), caused a significant increase in testes weights at each time point. On the other hand, LH or FSH/LH, but not FSH alone, caused a significant increase in the accessory organ weights. FSH had no effect on intratesticular testosterone (T) or on 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity but enhanced the in vitro response of interstitial cells to hCG. LH and FSH/LH had pronounced effects on intratesticular T, 3 beta-HSD activity, and in vitro response of interstitial cells to human chorionic gonadotropin. Treatment with FSH or FSH/LH caused regrowth of the testis and restoration of tubular lumen and tubular diameter and restored complete spermatogenesis. However, LH had little effect on spermatogenesis in spite of increased intratesticular and peripheral T levels. These results indicate that although LH can cause a full redifferentiation of Leydig cells in photoinhibited hamsters, it has only minor effects on tubular function. On the other hand, FSH alone induces full restoration of tubular function in these animals and has no direct effect on Leydig cell steroidogenesis, but may enhance the Leydig cell responsiveness to LH.

Modulation of benzene toxicity by polyinosinic-polycytidilic acid, an interferon inducer

Repeated intraperitoneal administration of benzene (1.0 ml/kg body wt.) for 3 days produced leucopenia, lymphocytopenia and significantly decreased body wt. (P less than 0.001) and organ weights of thymus (P less than 0.001) and spleen (P less than 0.001) in female albino rats. Total iron content, lipid peroxidation and superoxide dismutase activity of the liver and bone marrow were significantly increased as a result of benzene exposure. Low molecular weight (LMW) bleomycin detectable iron content was accumulated in bone marrow, whereas hepatic LMW iron was not detectable after benzene intoxication to rats. Prior administration of single dose (250 micrograms/100 g body wt.) of Poly IC, an interferon inducer with immunomodulating potential was found to be ameliorate some of the adverse effects of benzene as well as restoration of hepatic architecture histologically. Superoxide dismutase activity, lipid peroxidation, total iron content and LMW iron content (bone marrow) were normalised. Pretreatment of animals with Poly IC was able to enhance the SRBC antibody titre in benzene-treated animals. This study suggests that the beneficial effects of Poly IC in the amelioration of the acute toxicity of benzene has clinical significance.

Differentiation between androgen and estrogen receptor mediated effects of testosterone on FSH using androgen receptor deficient (Tfm) and normal mice

The comparison of normal and androgen receptor (AR) deficient Tfm-mice allows distinction between AR mediated and estrogen receptor (ER) mediated effects of testosterone (T)--the latter after aromatization of T to estrogens--on serum and pituitary FSH. Normal male and female as well as Tfm mice were gonadectomized after 8 days and treated for 11 days with either T, estradiol (E2) or vehicle. Serum and pituitary FSH was determined by RIA for rat FSH. In Tfm mice T caused a suppression of serum FSH, indicating an ER mediated effect. Lower serum FSH levels after T in normal mice than Tfm mice indicate an additional AR mediated suppression. Lower serum FSH values in E2 treated Tfm than in T treated Tfm mice--where T acts only through ER--suggest two classes of estrophilic cells: one which aromatizes, thus being susceptible for both T and E2, and the other which does not aromatize. Only AR but not ER mediated T effects on pituitary FSH could be demonstrated.

Appendicectomy stumps: 'to bury or not to bury'

A prospective randomized trial of 130 patients was carried out to compare simple ligature with invagination of the appendix stump. There were 64 and 66 patients, respectively, in the two groups and they were well matched for age, sex, weight and severity of appendicitis. One patient in the invagination group developed wound infection but there was no infection in the other group. This difference was not statistically significant (P greater than 0.5) and there was no evidence of adhesive ileus in either group after a mean follow-up period of nine months. We recommend simple ligature of the appendix stump as a safe procedure.

Effect of a Prudhoe Bay crude oil on hepatic and renal peroxisomal beta-oxidation and mixed-function oxidase activities in rats

The effect of oral administration of a Prudhoe Bay crude oil (PBCO) to male rats (PBCO, 2.6 g/kg body weight, daily) for 5-12 days on hepatic and renal microsomal monooxygenase activities and peroxisomal beta-oxidation has been investigated. PBCO administration leads to liver enlargement. This is associated with induction of microsomal cytochrome P-450 levels (1.6- to 2.0-fold) and dependent mixed-function oxidase activities (7-ethoxyresorufin-O-deethylase and 7-pentoxyresorufin-O-depentylase, representing cytochrome P-450I and cytochrome P-450IIB isoenzymes respectively, 9- to 15-fold; omega-oxidation of lauric acid representing the cytochrome P-450IVA1 isoenzyme, 1.4- to 1.5-fold) along with peroxisomal beta-oxidation (palmitoyl CoA oxidation, 2- to 5-fold). It was observed that rats exposed to PBCO showed an increase in renal microsomal cytochrome P-450 content (1.6- to 2.3-fold), cytochrome P-450I activity (5- to 8-fold) and omega-oxidation activity (1.3- to 1.4-fold). However, renal peroxisomal beta-oxidation was unaltered. Serum total triglycerides were lowered by 41-46% after PBCO exposure. These results suggest that induction of peroxisomal beta-oxidation and possibly mono-oxygenases may be related to the carcinogenic/tumorigenic potential of crude oil.

Effect of different dietary brans on lipid metabolism in male albino rats

Male albino rats were fed different dietary brans at 20% level for two months to study their effect on lipid metabolism. Wheat and corn brans significantly (P less than 0.05) decreased the serum cholesterol level while chickpea bran significantly (P less than 0.05) lowered the liver and heart cholesterol concentrations. Significant (P less than 0.05) reduction was observed in liver and heart triglyceride with all brans. Wheat, corn and chickpea brans fed at 20% level had no significant effect on serum triglyceride concentration.

Effect of roasting and autoclaving on phytic acid content of chickpea

Chickpea cultivars CM-68, C-44, Kabuli, CM-72 and 6153 were analysed for phytic acid, phytate phosphorus and total phosphorus. The effect of roasting and autoclaving on these constituents of whole seed and cotyledons was determined. The data revealed that roasting and autoclaving significantly decreased (P less than 0.05) the phytic acid of chickpea cultivars. Phytic acid of whole seed was reduced to a range value of 16-60% and 16-64% by roasting and autoclaving respectively depending upon the cultivar. In the cotyledon, the phytic acid was reduced to a range value of 32-68% and 18-68% during roasting and autoclaving respectively. Similar effect of these treatments was observed in phytate phosphorus however, total phosphorus was little affected.

Perturbation of liver microsomal calcium homeostasis by ochratoxin A

The effect of ochratoxin A on hepatic microsomal calcium sequestration was studied both in vivo and in vitro. The rate of ATP-dependent calcium uptake was inhibited by 42-45% in ochratoxin A intoxicated rats as compared to controls. In the presence of NADPH, addition of ochratoxin A (2.5 to 100 microM) caused a concentration-dependent inhibition of calcium uptake (28-94%) by untreated rat liver microsomes. The rate of NADPH-dependent lipid peroxidation, measured as malondialdehyde formed, was also greatly enhanced by ochratoxin A. Various agents that inhibited ochratoxin A enhanced lipid peroxidation were also able to block the destruction of calcium uptake activity. Lipid peroxidation enhanced by ochratoxin A was also accompanied by leakage of calcium from calcium-loaded microsomes. These results suggest that ochratoxin A disrupts microsomal calcium homeostasis by an impairment of the endoplasmic reticulum membrane probably via enhanced lipid peroxidation.

Ontogeny and cellular origin of an interleukin-1-like factor in the reproductive tract of the male rat

We have recently isolated an interleukin-1 (IL-1)-like factor from the rat testis, which originates from the seminiferous tubules and is a protein with an MW of 17,000 and a pI of 5-6. This paper reports on the appearance of the IL-1-like factor during postnatal development and investigates its cellular origin further. IL-1 activity was measured by a murine thymocyte proliferation assay. Very low IL-1 activity was present in culture medium conditioned by seminiferous tubules from rats aged 10 or 20 days. From 30 days of age, increasing amounts were detected, reaching a maximum level in adult animals (60-90 days). No IL-1 activity was found in medium conditioned by peritubular cells. Sertoli cell-enriched seminiferous tubules obtained from experimentally cryptorchid or from prenatally irradiated rats produced much higher levels of IL-1 activity than did those obtained from intact testes. IL-1 activity was detected in efferent duct fluid after ligation of the efferent ducts for 24 h, indicating that the IL-1-like factor was secreted into the tubular lumen. Low levels of IL-1 activity were detected in extracts of epididymal tissue and epididymal sperm, whereas ejaculated seminal plasma, seminal vesicle fluid and extracts of seminal vesicles (together with the coagulating glands) and ventral and dorsolateral prostate lacked IL-1 activity. Instead, seminal plasma inhibited testicular IL-1 activity dose-dependently without affecting cell viability in the thymocyte cultures. Although its biological function remains to be defined, our results indicate that the testicular IL-1-like factor is produced by Sertoli cells and that its appearance during development coincides with the initiation of active spermatogenesis in the rat testis.

In vivo determinations of labelling index of metastatic colorectal carcinoma and normal colonic mucosa using intravenous infusions of bromodeoxyuridine

In vivo determination of the labelling index of metastatic colon carcinoma was performed in 14 patients following intravenous infusion of bromodeoxyuridine (BrdU), at doses of 100 and 50 mg/M2. No toxicity was seen. Labelled cells were detected by an immunohistochemical technique using a monoclonal antibody to BrdU. Labelling was uniform and highly specific with good preservation of morphology. Labelling index values ranged from 15.0-40.6% for metastatic lesions and 3.6%-20% for normal colonic mucosa, with mean values of 24% and 11%, respectively. This represents a useful new method for in vivo labelling index determination in solid tumors.

Characterization of a novel anti-peptide antibody that recognizes a specific conformation of the platelet-derived growth factor receptor

Two site-specific anti-peptide antibodies (AbP1 and AbP2) were raised against the platelet-derived growth factor (PDGF) receptor. These two sites correspond to amino acid residues 977 through 988 (peptide 1) and 932 through 947 (peptide 2) of the murine PDGF receptor. Both antibodies recognized human and murine PDGF receptors in immunoprecipitation and immunoblotting analyses. None of the antibodies was directed to phosphotyrosine. One of the antibodies (AbP2) showed unusual antigen recognition specificity. This antibody specifically recognized the tyrosine-phosphorylated PDGF receptor and not the unphosphorylated native receptor, suggesting that recognition by this antibody requires a specific conformation that is induced by PDGF-stimulated autophosphorylation.

Comparison of the inhibitory effects of some compounds present in crude oils on rat platelet aggregation: role of intra- and extra- cellular calcium

In vitro addition of some representative aliphatic, aromatic or heterocyclic compounds present in petroleum crude oils to washed rat platelets resulted in a concentration-dependent inhibition of aggregation induced by ADP or thrombin. Increasing concentration of extracellular Ca2+ did not alter the pattern of inhibition. ADP-induced intracellular Ca2+ mobilization was unaffected by most of the compounds tested. However, Ca2+ uptake was significantly inhibited when platelets were preincubated with these agents. This suggests that some components of crude oil may inhibit platelet aggregation by bringing about alterations in the platelet plasma membrane.

Effects of mot gene expression on the structure of the flagellar motor

Direct freezing procedures have enabled us to visualize distinctive intramembrane particle ring structures in the cytoplasmic membranes of peritrichously flagellated bacteria by means of freeze-fracture electron microscopy. These structures were identified as flagellar motor components because their distribution matched that of flagella, and because they were absent in non-flagellated mutants of Escherichia coli. Particle rings were present in both the Gram-positive Streptococcus and the Gram-negative E. coli. In E. coli, a non-functional mocha operon produced flagellated but immotile cells lacking the particle rings. Simultaneous introduction of the motA and motB genes, led to recovery of both motility and the ring structures but neither gene alone was sufficient. The concomitant loss of the rings and motility is consistent with the ring particles having a central role in the flagellar motor.

Early post-pneumonectomy bronchial stump fistula

Bronchial stump fistula occurred on the seventh postoperative day in a 45-year-old man who underwent right pneumonectomy for T2N2M0 adenocarcinoma of the lung. It was attributable to ventilator-related barotrauma during treatment of ARDS from multiple pulmonary emboli. A frequently lethal complication, its presentation, management and prevention in the early postoperative period are discussed.