Effect of subchronic aflatoxin exposure on growth and progression of Ehrlich's ascites tumor in mice

The present investigation was undertaken to assess whether aflatoxin B1 (AFB1) has any modulatory effect on the growth and progression of Ehrlich's ascites tumor (EAT) in mice or not. Male Swiss albino mice were treated with 0, 70, 350 and 700 micrograms AFB1/kg body weight in 0.2 ml corn oil on alternate days, orally, for two weeks. Treated animals were challenged with 1 x 10(6) cells of Ehrlich's ascites tumor. Animals were monitored for the appearance of palpable tumor, body weight gain as a measure of tumor burden, mortality profile and tumor cell population. Some parameters of cell mediated immunity (CMI), humoral immunity and non-specific immunity were also studied in aflatoxin treated animals in order to find out the mechanism of action of AFB1 on host immunity. It was observed that AFB1 treatment resulted in an early appearance of tumor, enhanced mortality, appreciable increase in body weight gain and EAT cell population following tumor challenge, in comparison with the control animals. Aflatoxin treatment caused suppression of CMI including an impairment of macrophage function, while humoral immunity was not much affected. It may be concluded that impaired CMI and macrophage function might be contributing to the increased growth of EAT in the AFB1 treated animals. Our findings may be relevant in that when a host is exposed to aflatoxins concomitantly with other carcinogens and cancer causing situations.

The effects of staphylococcal protein A on human lymphokine-activated killer cell induction

Staphylococcal protein A (Cowan strain; SpA), a biologically active molecule capable of inducing augmented natural killer (NK) cell cytotoxicity, was studied in regard to its effects on lymphokine-activated killer (LAK) cell development. SpA, when co-cultured with interleukin-2 (IL-2) for 4 days, significantly augmented both LAK activity against NK-resistant M14 (melanoma) target cells and DNA synthesis of peripheral blood mononuclear cells (PBMC). This enhancement occurred with SpA concentrations of 1-100 micrograms/ml in a dose-dependent fashion; concentrations above 100 micrograms/ml were no more effective. When SpA (10 micrograms/ml) was added to PBMC cultures with various IL-2 concentrations, cytotoxicity was increased over controls with IL-2 alone. The peak cytotoxic effect reached a plateau at 80 U/ml IL-2. SpA alone induced early (day 1) cytotoxicity, which rapidly declined. SpA alone did not induce PBMC proliferation but it did increase expression of CD25 (Tac), IL-2 receptor alpha chain, on CD56(Leu19)-positive and -negative cells. The potentiating effect of SpA was significantly enhanced in serum-free medium. If either human AB serum or human IgG was added to cultures SpA-enhanced LAK cytotoxicity was diminished. The addition of anti-interferon gamma (anti-IFN gamma) antibody, but not anti-IFN alpha, inhibited (SpA+IL-2)-induced cytotoxicity, indicating that IFN gamma is partially responsible for the additive cytotoxic effect.

Detection of Mycobacterium leprae antigens in the sera of leprosy patients by sandwich immunoradiometric assay using monoclonal antibodies

An immunological technique for demonstration of Mycobacterium leprae antigen in sera was developed by using specific as well as cross-reactive monoclonal antibodies. The sandwich immunoradiometric assay which we developed is a simple, robust assay that is sensitive to the nanogram level. Sera from 72 leprosy patients were screened for the presence of antigen by this assay. A total of 69% of untreated tuberculoid leprosy patients showed 35-kDa antigen positivity, and 45% of these patients showed anti-35-kDa antibody positivity. Consistently higher antigen positivity rates for the 35-, 12-, and 30- to 40-kDa components of M. leprae were observed in lepromatous leprosy patients than in tuberculoid leprosy patients. During the course of therapy the antigen positivity rate gradually declined, and the antigen could not be detected in any of the 15 patients with subsided cases of leprosy. As antigen is presumably in excess before the antibody response is evoked, our experimental approach for antigen detection is likely to be useful by itself or along with antibody detection for diagnosis of early leprosy.

Effects of aflatoxin on lymphoid cells of weanling rat

Aflatoxin (AF), the hepatocarcinogenic food contaminant produced by the Aspergillus flavus group of fungi, is known to interact with various vital processes, including the immune function. Effects of long-term treatment of three dose levels of aflatoxin B1 (AFB1) on lymphoid cells of weanling rats were studied. AFB1 treatment caused a reduction in body weight gain, significantly (P less than 0.01) at the 700 microgram level. There was also a significant decrease in the weight of spleen and thymus in AFB1-treated animals in comparison to control. Similarly, AFB1 depleted cell populations of thymus and bone marrow and WBC and RBC counts. There was a marked reduction in the population and phagocytic capacity of macrophages due to AFB1 administration at dose levels of 350 and 700 micrograms kg-1 body weight. Macromolecular synthesis of DNA, RNA and protein in macrophages was affected, as there was significant inhibition in the incorporation of [3H]-thymidine, [3H]-uridine and [3H]-leucine. The hampered functioning of macrophages may be due to the cytotoxic action of AFB1.

Prevalence of sarcocysts of Sarcocystis capracanis in oesophagus and tail muscles of naturally infected goats

The prevalence of sarcocysts of Sarcocystis capracanis in oesophagus and tail muscles of 76 goats slaughtered at Jabalpur, India, was found to be 67.10 and 46.05%, respectively. A total of 79.3% of oesophagi and 72.4% of tails had sarcocysts in older goats (greater than 1 year), but their prevalence in younger animals (less than 1 year) was 40.0% in oesophagi and none in tails. Therefore examination by biopsy of the tail muscles can be used to monitor the development of Sarcocystis sarcocysts in experimental infection without killing the animal.

Protection against carbon-tetrachloride-induced lymphoid organotoxicity in rats by protein A

In a previous study we described protection of rats from carbon tetrachloride (CCl4)-induced hepatotoxicity by protein A (PA). In the present report we described protection against CCl4-induced lymphoid organotoxicity in rats by PA. Our data indicate that CCl4 administration produced a significant increase in the number of total leukocytes and polymorphs in blood, a significant decrease in leukocyte count in bone marrow, and a significant loss in weight of spleen and adrenals. In the animals receiving PA prior to and after CCl4, these values were found to be near those of controls. Histological examination revealed thymocyte depletion in thymic lobe and degenerative changes of tissue in spleen of CCl4-exposed animals. PA treatment to CCl4-exposed animals exhibited improvement and recovery from the damage caused by CCl4. These observations throw a new light on the field of CCl4 toxicity to lymphoid organs and their protection by PA.

Effect of piracetam, a nootropic agent, on experimental gastric ulcers in rat

Piracetam, used clinically for cognitive disorders, was found to have significant anti-ulcerogenic activity against immobilization stress- and aspirin-induced gastric ulcers in rats. The anti-ulcer effect of piracetam was exerted by augmentation of mucosal resistance. This was indicated by the significant attenuation of the decrease in total carbohydrate: protein ratio induced by aspirin. It also reversed the marked increase in gastric juice protein and DNA induced by aspirin, indicating that piracetam attenuated the augmented mucosal cell exfoliation induced by the ulcerogen. The drug also increased gastric mucosal serotonin concentrations. Piracetam, thus appears to have a profile of activity associated with cytoprotective agents.

A mixed model of carcinogenesis with applications to retinoblastoma

This paper presents a mixed model of carcinogenesis and derives the incidence functions and the first four cumulants of the number of tumors. The model is then fitted to some retinoblastoma data from the SEER (Surveillance Epidemiology End Results) project of the National Cancer Institute for the years 1973-1982. In all the cases presented, the estimated incidence functions appear to fit the observed incidence curves quite well, suggesting the usefulness of the model.

Superficially invasive carcinoma of the vagina following treatment for cervical cancer: a report of six cases

Six patients with superficially invasive squamous carcinoma of the vagina are described. All patients meet recently proposed criteria for the diagnosis of microinvasive vaginal carcinoma. The depth of invasion measured from the surface was less than 2.5 mm. There was no lymph-vascular space involvement. The invasive foci arose within a field of carcinoma in situ. Five of these six patients had previously been treated for invasive cervical cancer with pelvic radiation from 82 to 246 months before the diagnosis of vaginal carcinoma. All but one patient had the carcinoma confined to the upper one-third of the vagina. All patients were treated with a single vaginal radium application following vaginectomy. One of these six patients expired from recurrent vaginal cancer 35 months following diagnosis. During the same 17-year period, 17 other cases of Stage I epidermoid cancer of the vagina were treated which did not meet the above criteria for microinvasion. There were no statistically significant differences between these two groups with regard to age at diagnosis, history of cervical cancer, hysterectomy, or pelvic radiation or in survival. Additional experience with early vaginal carcinoma is needed before microinvasive carcinoma of the vagina should be accepted as a distinct clinical entity.

Protein A induced abrogation of cyclophosphamide toxicity is associated with concomitant potentiation of immune function of host

This report confirms our previous observation that protein A (PA) of Staphylococcus aureus Cowan I reduces the cyclophosphamide (Cy) induced toxicity. PA treated animals recover quickly from the toxic effects of Cy. We have exhaustively studied the role of specific and nonspecific immunity in the protection of the animals. It was observed that PA helped the animals in the accelerated regeneration of leukocytes of blood (p less than 0.001) and different lymphoid organs like thymus (p less than 0.001), spleen (p less than 0.01) and bone marrow (p less than 0.01). Increased number and function of macrophages was also observed in PA (p less than 0.001) and PA+Cy (p less than 0.001) groups. PA, on one hand enhanced the cell mediated immunity while suppressed the humoral immunity as was assessed by increase in delayed type hypersensitivity response (p less than 0.001) and decreased in plaque forming cells (p less than 0.001), EAC-rosettes (p less than 0.001), hemagglutination (p less than 0.001) and hemolysin titre (p less than 0.05). On the basis of above observations we propose that the immunomodulatory activity of PA helped the animals to remain alive in two ways- (1) by early generation of the cells depleted by the Cy thus helping animals to repair the damaged immune system and fast clearance of the toxic metabolites of Cy (2) by temporarily suppressing the cells responsible for humoral immunity which are more susceptible to Cy metabolites.

Variation of ascorbic acid content in the different tissues of the frog Rana tigrina as a function of season

Ascorbic acid concentrations of the liver, thigh, and cardiac muscles, ventral and dorsal skin, as well as muscles of the frog Rana tigrina were higher during summer and lower in winter. Ascorbate concentration also showed another high peak in February. The cardiac ascorbate showed minimal seasonal fluctuations.

Protein A protects mice from depletion of biotransformation enzymes and mortality induced by Salmonella typhimurium endotoxin

Changes in hepatic microsomal mixed-function oxidase enzyme levels (aniline hydroxylase, aminopyrine demethylase, glutathione S-transferase), glutathione content, total sulphydryl content, and plasma enzyme levels of aspartate transaminase, alanine transaminase and alkaline phosphatase were studied in male Swiss albino mice exposed to Salmonella typhimurium endotoxin (50-150 micrograms per mouse, LC50 141.82 micrograms). Animals exposed to the same dose of endotoxin but pretreated with protein A of Staphylococcus aureus (5 micrograms/per mouse) protected the animals from both mortality and depletion of biotransformation enzymes.

Ossifying fibroma of the maxilla. Case report

A rare case of ossifying fibroma presenting as a rapidly growing tumour of the maxillary antrum and causing destruction of its walls is described with a brief review of literature.

Clinically significant Streptococcus anginosus (Streptococcus milleri) infections: a review of 186 cases

We describe clinically significant infections due to Streptococcus anginosus in 186 patients; 114 (61.3%) males and 72 (38.7%) females, median age 42 years, range 9 months to 93 years. In 101 (54.3%) cases S anginosus alone caused infection and in 85 (45.7%) cases it was associated with other microorganisms. Abscesses accounted for 110 (59.1%) infections. Sites of infection were: miscellaneous skin and soft tissue, 64 (34.4%), intraabdominal 41 (22%), head and neck 34 (18.3%), pleuropulmonary 22 (11.8%), genitourinary 9 (4.8%), musculoskeletal 6 (3.2%), endocarditis 5 (2.7%) and primary bacteraemia 5 (2.7%). Treatment consisted of antibiotic therapy which was often prolonged, median 30 days, range 2-90 days, and surgery in 159 (85.5%). S anginosus infection was a contributory factor in two of the three deaths which occurred.

Protection against carbon tetrachloride-induced hepatotoxicity by protein A

Protection from carbon tetrachloride (CCL4)-induced hepatotoxicity by protein A was assessed histologically in rats. Carbon tetrachloride exposure produced swollen, vacuolated and necrotic cells in the centrilobular region of the hepatocyte in rats. Animals given protein A prior to and during CCL1 treatment showed a complete absence of hepatic lesions. Our study showed that protein A, a potent immunomodulator, has the potential to reduce liver injury caused by carbon tetrachloride, a known hepatotoxin in the rat.

In-vitro activity of fleroxacin compared with three other quinolones

The in-vitro activity of fleroxacin (Ro23-6240), a new synthetic quinolone, was compared with that of three other quinolones against 665 clinical isolates of aerobic bacteria by the agar dilution technique. Fleroxacin showed similar activity to norfloxacin, enoxacin and pefloxacin against most isolates of Enterobacteriaceae, Neisseria meningitidis, N. gonorrhoeae, Haemophilis influenzae, Staphylococcus spp. and streptococcus faecalis. Fleroxacin was the most active quinolone against Enterobacter spp. Fleroxacin was not as active against Pseudomonas aeruginosa, but the MIC90 (4 mg/l) is still below the reported peak serum level after a standard oral dose of 400 mg.

In vivo protection by protein A of hepatic microsomal mixed function oxidase system of CCl4-administered rats

The in vivo protection by protein A of hepatic mixed function oxidase system of carbon tetrachloride (CCl4) administered rats, has been investigated in the present communication. Aryl hydrocarbon hydroxylase activity was decreased by 63% in CCl4 administered rats while in protein A + CCl4 administered rats the decrease was in the range of 22-25% (group IV-V). The aryl hydrocarbon hydroxylase activity in protein A + CCl4 administered rats showed significant increase in group IV (P less than 0.005) and group V (P less than 0.001) in comparison to CCl4 alone (group II). Similarly, aniline hydroxylase and aminopyrene N-demethylase were decreased, by 75 and 84% respectively in CCl4 administered rats and 31% and 54-64%, respectively in protein A + CCl4 administered rats (groups IV and V). The aniline hydroxylase activity was also found enhanced in protein A + CCl4 administered group IV and V (P less than 0.001). In addition the aminopyrene N-demethylase also showed significant increase in its activity in group IV (P less than 0.001) and group V (P less than 0.001) in comparison to CCl4 alone. In accordance with these data, serum glutamic oxaloacetic transaminase and glutamic pyruvic transaminase exhibited significantly less increase in their activity in animals receiving protein A and CCl4 than those treated with CCl4 alone. Protein A alone was found to have no effect on any of these enzymes. Our results indicate that protein A protects CCl4 induced injury as judged by the biochemical alterations and suggests that it may be useful in providing an excellent system for the investigation on the regeneration of the hepatic enzyme activity following toxic insult of CCl4.

Assessing the effects of metabolism of environmental agents on cancer tumor development by a two-stage model of carcinogenesis

By combining the Michaelis-Menten kinetics of metabolism with the two-stage model of Moolgavkar and Knudson (1981) and the extended two-stage model of carcinogenesis proposed by Tan and Gastardo (1985), this paper proceeds to investigate the effects of metabolism of carcinogens on cancer tumor development. It is shown that the nonlinear kinetics of metabolism of carcinogens affect the dose-response relationship mainly through the mutation rates. If the initiator is affected by metabolism, then the metabolism of promoters has very little or negligible effects of the expected incidences and the number of tumors.