Burn injury induces a biphasic immunoglobulin M response to bacterial antigen.

We studied 75 BALB/c mice to examine the role of impaired immunoglobulin M (IgM) synthesis in the increased risk of bacterial infection after burn injury by investigating the kinetics of IgM synthesis to peptidoglycan polysaccharide (PGPS), a ubiquitous bacterial antigen. Splenocytes were isolated 1, 5, and 8 days postburn (PBD) and cultured with lipopolysaccharide for 5 days. Culture supernatant was collected and anti-PGPS IgM and total IgM levels were measured by ELISA. Total IgM-secreting cells were measured by ELISPOT assay. Total IgM and anti-PGPS IgM per IgM-secreting cell were calculated. On PBD 1, anti-PGPS IgM synthesis but not total IgM synthesis is increased in burned animals. By PBD 5, total IgM and anti-PGPS IgM synthesis in the burn group start to fall and by PBD 8, both are significantly decreased. The early increase in anti-PGPS IgM synthesis represents a positive response to bacterial challenge. However, the late nonspecific decrease in total IgM and anti-PGPS IgM synthesis suggests a potential mechanism for increased susceptibility to bacterial infection 5 to 10 days after burn injury.

Clostridium difficile infection in hamsters fed an atherogenic diet.

Diarrhea and unexpected death were encountered in a group of young Syrian hamsters (Mesocricetus auratus) used for hyperlipoproteinemia and atherosclerosis research. The animals were fed an atherogenic diet containing 18% saturated fat and 0.366% cholesterol. Mortality began 45 days after hamsters were placed on this atherogenic diet. The atherogenic studies were aborted at 74 days because of high mortality. Toxigenic Clostridium difficile was isolated from animals found dead or euthanatized because of illness. Signs observed were unexpected death and acute liquid diarrhea. Characteristic pathologic changes were necrosis and hemorrhage of the intestinal mucosa with acute inflammation. Hepatic lipidosis was a consistent finding presumed to be associated with the consumption of the atherogenic diet. The study was repeated by placing 23 hamsters on the atherogenic diet and 10 hamsters on the control diet. In animals fed the atherogenic diet, the average time to mortality differed between studies, but clinical signs, gross and histologic lesions, culture findings, and toxin results in both atherogenic diet groups were similar. C. difficile was not isolated from the feeds. No antibiotics were found in the atherogenic diet. The results from these studies suggest that hamsters fed an atherogenic diet have increased susceptibility to disease caused by C. difficile as compared with hamsters fed a normal fat and cholesterol diet.

Potentiation of 2,6-dinitrotoluene genotoxicity in Fischer 344 rats by pretreatment with coal tar creosote.

Pretreatment of male Fischer 344 rats for 5 wk with coal tar creosote, a coal distillation product that is widely used as a wood preservative, potentiated the excretion of urinary mutagens in 2,6-dinitrotoluene (DNT) treated rats. Creosote increased the bioactivation of DNT to significantly greater levels of urinary genotoxic metabolites and/or formed DNA adducts in the liver. A significant increase in the excretion of mutagenic DNT metabolites was observed after the first week of creosote treatment, peaked at wk 3, and then decreased by 33% after 5 wk of treatment. Nevertheless, there was a significant increase (66%) in the formation of DNT-derived DNA adducts in the livers of rats treated with DNT plus creosote at wk 5. Increased cecal beta-glucuronidase activity and reduced small intestinal nitroreductase activity may play roles in the bioactivation of DNT. The excretion of mutagenic DNT metabolites supplies useful information about the bioactivation of DNT; it does not provide a useful index of DNT-derived hepatic DNA adduct formation. Such interactions could be important to predictive risk assessment because the overall cancer risk of such chemical mixtures may exceed the sum of the component risks.

Microbial succession and intestinal enzyme activities in the developing rat.

The succession of gut bacteria and selected intestinal enzyme activities in developing 7-35-d-old rats was studied. Aerobes and anaerobes were identified as members of four broad major bacterial groups, i.e. Gram-positive rods, Gram-positive cocci, Gram-negative rods and obligate anaerobes. The enzyme activities of nitro and azo reductases, beta-glucuronidase, dechlorinase and dehydrochlorinase were determined by anaerobic incubation of intestinal homogenates with 3,4-dichloronitrobenzene, methyl orange, p-nitrophenyl-beta-D-glucuronide, and p,p'-DDT respectively. Nitroreductase and azo reductase activities increased significantly with the appearance of anaerobes in the large intestine. No increase in either nitroreductase or azo reductase activities in the small intestine was found. The early and high level of beta-glucuronidase activity in the small and large intestines coincided with high numbers of coliforms recovered in 7 and 14 d animals. Dehydrochlorinase activity appeared early but was undetectable at both 21 and 28 d. Its activity increased at 35 d. Dechlorinase activity was variable in development. The rapid changes in the microbial flora and intestinal enzyme activities may influence the susceptibility of pre-pubescent rats to a variety of toxicants. Therefore, age-dependent toxicity may be important in the risk assessment of some environmental chemicals.

Potentiation of 2,6-dinitrotoluene genotoxicity in Fischer-344 rats by pretreatment with Aroclor 1254.

Pretreatment of Fischer 344 rats for 5 weeks with Aroclor 1254, a commercial mixture of polychlorinated biphenyls, potentiated the genotoxicity of 2,6-dinitrotoluene (DNT), a component of an industrial chemical used in the production of polyurethane foams. This interaction resulted from Aroclor 1254-mediated bioactivation of DNT to markedly greater levels of the genotoxic metabolites, that were excreted in urine and formed DNA adducts in the liver. A significant increase in the excretion of mutagenic urinary DNT metabolites was observed after the first week of Aroclor 1254 treatment, peaked at week 2 and then declined by nearly 25% at week 4. Nevertheless, by week 5, there was almost a 4-fold increase in the formation of hepatic DNA adducts. Significantly elevated hepatic metabolism and increased beta-glucuronidase in the small intestine and cecum, at 4 weeks, may account for the increased adducts and decreased urinary mutagens. Altered nitroreductase activity, reduced pH, and changes in the microfloral population may also play a role in the effect of Aroclor 1254 on the bioactivation of DNT. Such chemical interactions could be important to predictive risk assessment because the overall cancer risk of the mixture would exceed that determined by the current guidelines for chemical mixtures.

Carboplatin/cyclophosphamide combination chemotherapy for advanced ovarian cancer.

The efficacy and toxicity of combination intravenous carboplatin (300 mg/m2) and cyclophosphamide (600 mg/m2) were evaluated in 70 newly diagnosed patients with advanced-stage epithelial ovarian cancer. Cycles were administered at 4-week intervals for a total of six cycles, and treatment was provided on an outpatient basis without prehydration or forced diuresis. During treatment, patients were assessed by physical, gynecologic, and radiologic examinations. Seventy patients with a median age of 58 years (range, 35 to 77 years) were entered into the study. Most patients had serious cystadenocarcinoma; 78% had stage III or IV disease and 91% had grade II or III histologic subtype. Optimal debulking surgery was performed in only 46% of patients. The overall response rate to carboplatin/cyclophosphamide combination chemotherapy was 81%, with 66% achieving a clinical complete response. The median survival for all patients was 19+ months. For patients who had undergone optimal debulking surgery, median survival was 26 months, compared with a median survival of 13+ months for those who had undergone suboptimal surgery. Treatment was well tolerated by most patients. Significant nausea and vomiting (World Health Organization grades 2 to 3) occurred in only 6% of 377 cycles of therapy. Myelosuppression was mild, with leukopenia (WBC count less than or equal to 2 x 10(9)/L) observed in only 11 of 295 cycles (4%) and thrombocytopenia (less than or equal to 100 x 10(9)/L) in 17 of 279 cycles (6%). Nadir levels generally occurred on day 21 of each cycle. Symptomatic anemia requiring transfusion occurred in 18 of 290 cycles (6%). Moderate alopecia, necessitating use of a hairpiece, occurred in six patients; no signs or symptoms of neurotoxicity, ototoxicity, or nephrotoxicity were observed in any patient. Renal function was normal on follow-up investigation, which was performed a median of 5 months after completion of treatment. This study demonstrates that carboplatin/cyclophosphamide combination chemotherapy is well tolerated in women with advanced-stage epithelial ovarian cancer, and produces overall response rates and median survival times similar to those obtained with cisplatin-containing regimens.

2,4,5-trichlorophenoxyacetic acid influence on 2,6-dinitrotoluene-induced urine genotoxicity in Fischer 344 rats: effect on gastrointestinal microflora and enzyme activity.

2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) and 2,6-dinitrotoluene (2,6-DNT) are hazardous chemicals that have potential harmful effects. 2,6-DNT is recognized as a hepatotoxicant while 2,4,5-T, a component of Agent Orange, is also suspect. 2,6-DNT requires both oxidative and reductive metabolism to elicit genotoxic effects. To determine what effect 2,4,5-T had on 2,6-DNT metabolism, intestinal enzymes, microbial populations, and urine mutagenicity were examined during 2,4,5-T treatment. Weanling Fischer 344 male rats were treated daily with 54.4 mg/kg 2,4,5-T by gavage for 4 weeks. One, two, and four weeks after the initial 2,4,5-T dose, rats were administered (po) 2,6-DNT (75 mg/kg) and urine was collected for 24 hr in metabolism cages. Azo reductase, nitroreductase, beta-glucuronidase, dechlorinase, and dehydrochlorinase activities were examined concurrently. Treatment of rats for 1 week reduced the transformation of 2,6-DNT to mutagenic urinary metabolites. This was accompanied by a decrease in the fecal anaerobic microorganisms. The elimination of Lactobacillus fermentum from the small intestine and cecum of treated animals accompanied a significant increase in oxygen-tolerant lactobacilli and other unidentified aerobic microorganisms. However, there were no significant alterations in the intestinal enzyme activities examined. By 2 weeks of 2,4,5-T treatment, microbiota and urine genotoxicity returned to the levels observed in control animals. This trend continued for the duration of the experiment. After 2 weeks, while cecal nitroreductase and azo reductase activities increased, small intestinal beta-glucuronidase activity decreased. By 4 weeks, treated and untreated animal intestinal enzyme activities were indistinguishable.(ABSTRACT TRUNCATED AT 250 WORDS)

Hematology, serum chemistry values, and rectal temperatures of adult greater galagos (Galago garnetti and G. crassicaudatus).

Hematological and serum chemistry values, as well as rectal temperatures, were obtained from greater galagos (Galago garnettii and G. crassicaudatus), in order to establish normative values. No species or sex differences were found for four hematological parameters and 15 serum chemistry parameters. Species differences were seen in phosphate, magnesium, cholesterol, alkaline phosphate, G-glutamyl transferase, mean corpuscular volume and leucocyte, neutrophil, and lymphocyte number. Significant sex differences were observed in glucose, hemoglobin, and hematocrit values. Species and sex differences were seen in chloride and erythrocyte number.

Selective beta-adrenoceptor partial agonist effects of pindolol and xamoterol on skeletal muscle assessed by plasma creatine kinase changes in healthy subjects.

1. The effects of selective beta-adrenoceptor partial agonist activity on plasma creatine kinase (CK) and skeletal muscle symptoms were studied in normal volunteers. 2. A drug with beta 1-selective partial agonist activity (xamoterol) and one with partial agonist activity acting mainly through beta 2-adrenoceptors (pindolol) were each given for 3 weeks in a randomised double-blind crossover study in 10 subjects. Five additional subjects received only one drug. Plasma CK levels were monitored during a baseline placebo run-in phase, the active treatment period and a placebo washout phase which continued until CK levels returned to baseline. 3. The degree of beta-adrenoceptor antagonism was determined by the inhibition of exercise-induced tachycardia and was similar for the two drug doses used. 4. During pindolol administration plasma CK levels rose compared with pretreatment baseline levels and with levels during xamoterol administration which did not rise. After pindolol was withdrawn CK levels reached higher peaks in some subjects after 1-5 days. 5. Muscle cramps were reported by five subjects during pindolol administration and by one of these subjects but to a lesser extent during xamoterol administration. 6. Pindolol may produce this effect, which was not seen with xamoterol, because of its specific beta 2-adrenoceptor partial agonist activity. Elevations in plasma CK produced by this type of drug or its withdrawal may cause confusion in the diagnosis of muscle disease or myocardial infarction unless the myocardial isoenzyme is measured.

First-dose effects of enalapril and atenolol upon blood pressure and cerebral blood flow in patients with mild hypertension on diuretic therapy.

The present single-blind, randomised, cross-over, placebo-controlled study was set up to compare the first-dose effects upon blood pressure (BP) and cerebral blood flow (CBF, measured by Xenon inhalation) of a single oral dose of atenolol 50 mg and enalapril 5 mg in ten hypertensive patients receiving a thiazide diuretic. It was found that a) the timing and degree of fall in BP after the first dose of atenolol and enalapril on a diuretic background were similar and generally not associated with symptoms or a fall in CBF, and b) dizziness, which is sometimes associated with the first-dose effect of ACE inhibitors in hypertensives on diuretics, can occasionally occur accompanied by a substantial fall (43%) in CBF in the absence of marked falls in systolic blood pressure. It is suggested that the latter event may be linked to a disturbance of cerebral autoregulation in part dependent on localised renin-angiotensin systems.

Acute effects of smoking on blood pressure and cerebral blood flow.

Chronic smoking, particularly in hypertensives, is associated with an increased frequency of cerebral infarction and subarachnoid haemorrhage; cerebral blood flow (CBF) is also decreased in chronic smokers. The acute effects of smoking upon CBF are less clear. The present study in six volunteers investigated the immediate effects of smoking (and inhaling) three cigarettes, each separated by a 2 hr gap, upon heart rate, blood pressure (BP) and CBF assessed by xenon inhalation and flow velocities in the middle cerebral artery by transcranial Doppler ultrasound. Smoking caused significant increases in heart rate, BP and middle cerebral artery flow velocities, and a significant fall in CBF (individual falls in hemispherical flow could be as great as 40%). These haemodynamic effects are probably caused by nicotine-induced changes in catecholamine release. The possible clinical significance of the BP and CBF changes induced by acute smoking in high-risk groups is discussed.

Stress/catecholamine-induced cardiac necrosis. Reduction by beta 1-selective blockade.

Catecholamine-induced cardiac necrosis is a well-described phenomenon. Patients with severe head injury are known to be in a marked hyperadrenergic state and can experience cardiac morbidity; this was confirmed in a pilot study. A further study was then undertaken to examine a possible relationship between plasma catecholamine concentration and cardiac morbidity in patients with severe head injury and to assess the effect of intervention with the beta 1-selective agent atenolol. The study involved 114 hemodynamically stable patients with acute head injury who were randomized, double blind, to either placebo or atenolol given intravenously (10 mg every six hours) for three days and then orally (100 mg once a day) for four days. Both groups were equally stressed in terms of raised arterial norepinephrine levels. In patients receiving placebo, but not in those given atenolol, there was a significant (P less than 0.01) positive correlation between arterial level of norepinephrine and plasma level of cardiac-specific isoenzyme CK-MB. Thirty percent of the placebo group, in contrast to 7.4% of the atenolol group (P less than 0.05), had pathologically elevated CK-MB levels (ie, greater than 3% of total CK, a value compatible with acute myocardial infarction). Atenolol appeared to significantly reduce the likelihood of supraventricular tachycardia and ST-segment and T-wave changes and prevented cardiac necrosis (as determined post mortem). The finding that beta 1-selective blockade significantly inhibits catecholamine-induced necrosis has possible broad clinical implications.

Reduction of stress/catecholamine-induced cardiac necrosis by beta 1-selective blockade.

114 haemodynamically stable patients with acute head injury were randomised, double-blind, to either placebo or atenolol given intravenously (10 mg every 6 h) for 3 days then orally (100 mg daily) for a further 4 days. Both groups were equally stressed as shown by raised arterial noradrenaline levels. In patients receiving placebo, but not in those receiving atenolol, there was a significant (p less than 0.01) positive correlation between arterial noradrenaline and levels of the myocardial isoenzyme of creatine kinase (CKMB). 30% of the placebo group compared with 7.4% of the atenolol group (p less than 0.05) showed CKMB levels greater than 3% of total creatine kinase (compatible with myocardial damage). CKMB levels greater than 6% of total creatine kinase (compatible with acute myocardial infarction) were present in 16.7% of patients receiving placebo but in no patients receiving atenolol (p = 0.053). Atenolol appeared to reduce significantly the likelihood of supraventricular tachycardia and ST-segment and T-wave changes and prevented cardiac necrosis seen at necropsy.

A comparison of phospholipase activity, cellular adherence and pathogenicity of yeasts.

Phospholipase A and lysophospholipase activities were measured in the culture fluid and in the blastospores of Candida albicans. When phospholipase activity was measured in six yeasts (four strains of C. albicans and a single strain each of Candida parapsilosis and Saccharomyces cerevisiae) a correlation was found between this activity and two potential parameters of pathogenicity. The C. albicans isolates which adhered most strongly to buccal epithelial cells and were most pathogenic in mice had the highest phospholipase activities. Non-pathogenic yeasts, including C. albicans isolates which did not adhere and did not kill mice, had lower phospholipase activities.

Yersinia enterocolitica infection in breeding colonies of ruffed lemurs.

Two outbreaks of yersiniosis caused by Yersinia enterocolitica occurred in breeding colonies of red ruffed lemurs (Varecia variegata rubra) and black and white ruffed lemurs (Varecia variegata variegata) housed in outdoor enclosures during the winter breeding season and spring birth season, respectively. Seven of 11 animals at risk in the combined outbreaks became ill, and 3 died of acute to chronic infection. Clinical signs included anorexia, lethargy, diarrhea, abdominal pain, and hyperpyrexia. Necropsy findings included ulcerative enterocolitis and multifocal necrosis and abscess formation in mesenteric lymph nodes, liver, spleen, kidneys, and lungs. Histologically, lesions were characterized by necrotizing inflammation containing masses of basophilic bacteria. Yersinia enterocolitica serotype 0:2 was isolated from lesions. Neomycin sulfate given orally and chloramphenicol given intramuscularly were effective in treatment early in the course of the disease or in mild cases. In severe cases, lemurs did not respond to antibiotic and fluid therapy. Exposure to soil contaminated with infected rodent feces, stress, and behavioral factors in the ruffed lemur species are believed to have precipitated the infection.