Toxicity of aflatoxin B1 in broiler chicks and its reduction by activated charcoal

Lipoprotein (a) (Lp(a)) is a plasma lipoprotein of high atherogenicity and competes with plasminogen at the site of plasminogen receptors. It is known that diabetic patients show a hypercoagulable state which might contribute to diabetic vascular complications. In the present study, mean levels of plasma Lp(a) and parameters of coagulation and fibrinolysis such as thrombin-antithrombin III complex (TAT) and alpha 2 plasmin inhibitor-plasmin complex (alpha 2PIC) were elevated in diabetic patients with nephropathy compared to healthy controls. A significant positive correlation was observed between the plasma levels of Lp(a) and alpha 2PIC (p < 0.05). Plasma levels of alpha 2PIC showed a significant positive correlation with those of TAT in the diabetic group, while there was no significant correlation observed in the non-diabetic group. The present results suggest that factors of Lp(a) and coagulation-fibrinolytic systems interacted, contributing to vascular complications in diabetic patients with nephropathy.     

In vitro metabolic N- and C-oxidation of phenanthridine

In order to compare an acceleromyograph (TOF-Guard) with a mechanomyograph (Grass FT03), the dose-response relationship of rocuronium was simultaneously determined in both arms of 15 children aged 3-11 years during anaesthesia with thiopentone, alfentanil and nitrous oxide. Three subgroups of five children received rocuronium 120, 180 or 240 micrograms.kg-1 randomly. The effective doses to produce 50% and 95% depression of the first twitch of the train-of-four determined by acceleromyography were 206 and 337 micrograms.kg-1, respectively, while these values determined by mechanomyography were 151 and 331 micrograms.kg-1, respectively. The dose-response curve obtained by acceleromyography was steeper and shifted to the right compared with that obtained by mechanomyography (p < 0.0001). The difference between the effective dose producing 50% twitch depression determined by the two devices was highly significant (p < 0.0001). In 13 out of 15 children, the acceleromyograph control train-of-four ratio was significantly greater than unity. Although there was a good correlation (r = 0.85) between simultaneous pairs of measurements of neuromuscular block, the acceleromyograph exhibited a bias of -25% relative to the mechanomyograph with wide limits of agreement (-62 to +12%). We conclude that acceleromyographic and mechanomyographic measurements should not be used interchangeably when determining the potency of muscle relaxants.     

Effect of aflatoxin B in vitro on rat liver mitochondrial respiratory functions

PURPOSE: A first case of massive venous air embolism is reported as a complication of orthotopic liver transplantation in a 17-month-old child during the dissection phase. CLINICAL FEATURES: During the hepatic dissection phase, perforation of suprahepatic veins was responsible for an air embolism with a decrease of P(ET)CO2 (27 to 6 mmHg), hypoxaemia (SpO2 decreased from 100 to 88%), and haemodynamic instability (systolic blood pressure decreased from 85 to 50 mmHg, central venous pressure increased from 6 to 10 mmHg). Central venous aspiration of air was unsuccessful but immediate resolution occurred and neurological outcome was normal. CONCLUSION: Venous air embolism during the dissection phase of liver transplantation in children is a risk that should be considered     

Preparation of aflatoxin B1 8,9-epoxide using m-chloroperbenzoic acid

A case of 26-years old man with symptoms of infectious mononucleosis syndrome is presented. In the course of the disease: high temperature, weakness, loss of appetite, sore throat, myalgia, hepatomegaly, splenomegaly and some laboratory changes (leucocytosis with presence of atypical lymphocytes, elevated aminotransferase activity) have been observed. Serological tests have shoved: slighthly positive PBD-test in the first examination (second-negative) and the presence of IgM antibodies against CMV in a high titer with four-time decrease of the titer during the course of the disease. Because of the incomplete symptom complex for infectious mononucleosis caused by EBV we have put the diagnosis of cytomegaly coursed as a infectious mononucleosis syndrome.     

In vitro microsomal metabolic studies on secondary aromatic amides

Previous studies showed that amides are metabolites arising from certain secondary aromatic amines. However, some analogue amines did not lead to the formation of the corresponding amides when metabolised under identical conditions. We, therefore, wished to establish the factors preventing detection of amides. In the present study, we thought that amide detection as metabolites from secondary anilines may depend on the hydrolytic rate of the corresponding amide. We studied the in vitro hepatic microsomal metabolism of four aromatic amides i.e. N-(4-nitrobenzoyl)aniline (N4NBZA), N-benzoyl-4-nitroaniline (NBZ4NA), N-benzoylaniline (NBZA) and N-benzoyl-2,4,6-trimethylaniline (NBZTMA) which were (or not) detected following microsomal metabolism of secondary anilines in previous studies. Following the preparation, characterisation and separation of substrates and potential metabolites, incubations were carried out using rabbit microsomal preparations fortified with NADPH. The substrates and potential metabolites were extracted into dichloromethane and analysed by TLC, HPLC and UV. The results indicated that both steric and electronic factors may influence hydrolysis of amides. Three amides i.e. N4NBZA, NBZ4NA and NBZA yielded hydrolytic metabolites, whereas, NBZTMA did not. Para hydroxylated metabolites were also detected from N4NBZA and NBZA. These observations support the concept that one reason for not detecting amides as metabolites from secondary anilines in previous studies could be due to their rapid hydrolysis to the corresponding primary amines.     

Production of aflatoxicol from aflatoxin B1 by postmitochondrial liver fractions

Fish liver postmitochondrial supernatant preparations in the presence of carbon monoxide were used to prepare purified aflatoxicol from aflatoxin B1 in high yield (23-38%). Such fish liver postmitochondrial and postmicrosomal supernatant preparations were five to ten times more active in making aflatoxicol than rat or human liver preparations under the same conditions.     

In vivo and in vitro characterization of the B1 and B2 zinc-binding domains from the acute promyelocytic leukemia protooncoprotein PML

Acute promyelocytic leukemia (APL) has been ascribed to a chromosomal translocation event which results in a fusion protein comprising the PML protein and retinoic acid receptor alpha. PML is normally a component of a nuclear multiprotein complex which is disrupted in the APL disease state. Here, two newly defined cysteine/histidine-rich protein motifs called the B-box (B1 and B2) from PML have been characterized in terms of their effect on PML nuclear body formation, their dimerization, and their biophysical properties. We have shown that both peptides bind Zn2+, which induces changes in the peptides' structures. We demonstrate that mutants in both B1 and B2 do not form PML nuclear bodies in vivo and have a phenotype that is different from that observed in the APL disease state. Interestingly, these mutations do not affect the ability of wild-type PML to dimerize with mutant proteins in vitro, suggesting that the B1 and B2 domains are involved in an additional interaction central to PML nuclear body formation. This report in conjunction with our previous work demonstrates that the PML RING-Bl/B2 motif plays a fundamental role in formation of a large multiprotein complex, a function that may be common to those unrelated proteins which contain the motif.     

In vitro transformation by hepatitis B virus DNA

There is strong epidemiological evidence that the hepatitis B virus (HBV) contributes to the development of hepatocellular carcinoma (HCC). In several immortalized cell lines, an in vitro transforming activity of HBV DNA and expression vectors for the viral protein X (HBx) has now been demonstrated. Furthermore, it appears as if still unknown parts of the HBV genome other than HBx contribute to the transforming activity of HBV DNA in vitro. Only one of several studies found that HBx-transgenic mouse lines develop HCC. A mouse line transgenic for the large surface protein of HBV develops HCC due to concomitant necroinflammatory infection. Growing evidence shows the importance of recombination of integrated viral DNA and cellular DNA for HCC development. A direct transforming potential of one of these viral integrates has been demonstrated. Chemical carcinogens are more effective in HBV-containing cell lines or transgenic mice.     

In vitro suppression of programmed cell death of B cells by tissue inhibitor of metalloproteinases-1

Cellular pathways for induction of programmed cell death (PCD) have been identified, but little is known about specific extracellular matrix processes that may affect apoptosis along those pathways. In this study, a series of Burkitt's lymphoma (BL) cell lines were assayed for their expression of tissue inhibitor of metalloproteinases (TIMP)-1. Results indicate that TIMP-1-positive BL lines show resistance to cold-shock-induced apoptosis. Furthermore, recombinant TIMP-1, but not TIMP-2 or a synthetic metalloproteinase inhibitor (BB-94), confers resistance to apoptosis induced by both CD95-dependent and -independent (cold shock, serum deprivation, and gamma-radiation) pathways in TIMP-1-negative BL lines. TIMP-1 suppression of PCD is not due to metalloproteinase inhibition, as reduction and alkylation of the TIMP-1 did not abolish this activity. Retroviral induction of TIMP-1 not only resulted in cell survival but also in continued DNA synthesis for up to 5 d in the absence of serum, while controls underwent apoptosis. This resistance to apoptosis is reversed by anti-TIMP-1 antibodies, demonstrating that secreted TIMP-1 is active in blocking apoptosis. Furthermore, TIMP-1 upregulation induced expression of Bcl-XL but not Bcl-2 as well as decreased NF-kappaB activity as compared with controls. These results demonstrate that TIMP-1 suppresses apoptosis in B cells and suggests a novel activity for TIMP-1 in tissue homeostasis.     

In vitro study of the mechanical effects of shock-wave lithotripsy

Impulsive stress in repeated shock waves administered during extracorporeal shock-wave lithotripsy (ESWL) causes injury to kidney tissue. In a study of the mechanical input of ESWL, the effects of focused shock waves on thin planar polymeric membranes immersed in a variety of tissue-mimicking fluids have been examined. A direct mechanism of failure by shock compression and an indirect mechanism by bubble collapse have been observed. Thin membranes are easily damaged by bubble collapse. After propagating through cavitation-free acoustically heterogeneous media (liquids mixed with hollow glass spheres, and tissue) shock waves cause membranes to fail in fatigue by a shearing mechanism. As is characteristic of dynamic fatigue, the failure stress increases with strain rate, determined by the amplitude and rise time of the attenuated shock wave. Shocks with large amplitude and short rise time (i.e., in uniform media) cause no damage. Thus the inhomogeneity of tissue is likely to contribute to injury in ESWL. A definition of dose is proposed which yields a criterion for damage based on measurable shock wave properties.     

The effect of pre-treatment with phenobarbitone on the activation of aflatoxin B1 by rat liver

Microsomes prepared from rats pre-treated with phenobarbitone are more effective in activating aflatoxin B1 in vitro to a metabolite which inhibits RNA polymerase than are microsomes obtained from control animals. This result is in contrast with the situation in vivo where pre-treatment with phenobarbitone protects against inhibition of RNA synthesis by aflatoxin B1. The hypothesis is advanced that, in vivo, the activation of aflatoxin B1 which is significant in terms of inhibition of nucleic acid synthesis largely occurs on the outer nuclear membrane, and that by increasing activation by the microsomes, phenobarbitone pre-treatment reduces the amount of aflatoxin B1 available for the nuclear activation.     

In vitro wear, hardness, and conversion of diacetyl-containing and propanal-containing resin materials

Eighty-two patients were treated in a split mouth design with coronal scaling (CS), root planing (RP), modified Widman surgery (MW), and flap with osseous surgery (FO) which were randomly assigned to the various quadrants in the dentition. Following phase I and phase II therapy, the patients received supportive periodontal treatment (SPT) at 3-month intervals for up to 7 years. Clinical attachment level (CAL) was determined initially, post-phase I, post-phase II and prior to each SPT appointment. If a site lost > or = 3 mm of CAL from its baseline, it was classified as a breakdown site. Baselines were the initial exam for sites treated by CS and 10 weeks post-phase II for sites treated by RP, MW, and FO. Data were grouped by probing depth (PD) severity at the initial exam and at post-phase II. The breakdown for CS sites was assessed separately from RP, MW, and FO sites because of different baselines and retreatment protocols. Sites treated by CS had a higher incidence of breakdown than the other therapies through year 1 of SPT. The breakdown incidences/year for RP and MW sites were similar and greater than for FO sites in 1 to 4 mm and 5 to 6 mm PD categories. Breakdown incidence of RP sites was greater than MW sites which was greater than FO sites initially > or = 7 mm. Differences in incidence of breakdown between therapies after recategorizing data by post-phase II PD were the same as above, except no difference was present between RP and MW sites > or = 7 mm. Breakdown incidences were greater in increasing PD severities regardless of when they were categorized. There was no further loss of CAL one year after retreatment in 88% of sites. Patients with higher breakdown incidences tended to be smokers at the initial exam.     

Genotoxicity of aflatoxin B1: evidence for a recombination-mediated mechanism in Saccharomyces cerevisiae

The potent liver carcinogen aflatoxin B1 (AFB1) is metabolized by cytochrome P450 to the mutagenic epoxide. We have observed that activated AFB1 also strongly induced mitotic recombination in the yeast Saccharomyces cerevisiae. To compare the recombinogenicity of AFB1 to its mutagenicity, three metabolically competent S. cerevisiae strains have been constructed. The frequencies of induced recombinants resulting from gene conversion or chromosomal translocations were determined by different prototrophic selections using two strains, whereas the inducibility of forward mutations was determined by the frequency of drug resistance in the third strain. Human cytochrome P4501A1- (CYP1A) and NADPH-cytochrome P450-oxidoreductase cDNAs were expressed in the strains to ensure intracellular metabolism to the epoxide. Exposure of the strains to AFB1 resulted in a 139- and 24-fold increase in the translocation and gene conversion frequencies, respectively, whereas the mutation frequency was increased only 3-fold. In contrast, benzo[a]pyrene-7,8-dihydrodiol and ethyl methanesulfonate induced mutation and mitotic recombination to similar degrees. We conclude that AFB1 exerted a strong recombinogenic, but only a weak mutagenic, effect. The recombinogenicity of AFB1 in yeast may indicate a mechanism for the high proportion of loss of heterozygosity that has been detected in AFB1-related human liver cancers.     

Mass spectral identification and positional mapping of aflatoxin B1-guanine adducts in oligonucleotides

The hemodynamic effects of sympathetic nervous system stimulation and the benefits of catecholamine blockade in patients with congestive heart failure (CHF) are discussed. Prolonged stimulation of the sympathetic nervous system promotes disease progression in patients with CHF. The level of circulating norepinephrine is the factor most closely correlated with prognosis. Long-term catecholamine stimulation of beta-receptors in the myocardium reduces the ability of catecholamines to improve cardiac contractility. CHF patients have higher vascular resistance (afterload) than healthy persons, increasing the strain on the heart. Also, beta 1-adrenergic activity stimulates renin release, which is deleterious in CHF. Clinical trials suggest that long-term (greater than one month), carefully dose-adjusted therapy with beta-blockers improves symptoms, ventricular ejection fraction, exercise time, and quality of life in patients with CHF, but it is unclear whether beta-blockers reduce mortality. Some patients cannot tolerate even the lowest starting dosages of beta-blockers, and withdrawal of these agents may result in clinical and hemodynamic deterioration. Carvedilol, which has beta-blocking, alpha-blocking, and antioxidant properties, is associated with a reduction in hospitalizations and symptoms and improvements in ejection fraction it also appears to reduce mortality, although confirmatory studies are needed. Initiation of carvedilol therapy can cause symptomatic and hemodynamic worsening in the short term, and some patients cannot tolerate it. Adrenergic blocking agents are important components of therapy for CHF. Carvedilol may prove useful in reducing symptoms and improving survival in these patients.     

In vitro activity of guinea pig transfer factor released into plasma

Plasma fractions and plasma dialysate from 2,4-dinitrochlorobenzene- and tuberculin-sensitive guinea pigs that had been treated with either antilymphocytic serum or normal control serum were analyzed for their ability to transfer lymphocyte transformation, passive cutaneous anaphylaxis, and macrophage migration inhibition, as well as delayed hypersensitivity in vivo. Antilymphocytic serum caused rapid release of material, which has characteristics of transfer factor, into the plasma. It was dialyzable, migrated electrophoretically with the alpha globulins and albumin, possessed a 280/260 (nm) optical density ratio of 0.7, and caused in vitro lymphocyte transformation in the presence of the specific antigen. Passive cutaneous anaphylaxis antibodies were also present in the plasma of sensitive animals, but they were isolated in electrophoretic or dialysis fractions separate from those containing transfer activity.