Nucleotide sequence and the molecular evolution of a new A2 gene in the DQ subregion of the bovine major histocompatibility complex

cDNA clones encoding the bovine major histocompatibility complex (MHC) class II DQ alpha chain were isolated. One clone, MQ9, encoded a primary translated product of 255 amino acids, with a signal peptide of 23 amino acids and a mature polypeptide of 232 amino acids. A new A2 gene in the DQ subregion of the bovine genome was identified from a comparison of amino acid sequences encoded by class II A genes among several species and the construction of a phylogenetic tree. It was revealed that MQ9 is most closely related to the ovine DQA2 genes among sequences from various mammalian species. By contrast, the BoLA-DQA genes previously isolated are more closely related to ovine DQA1 than to the BoLA-DQA2 gene, and they represent BoLA-DQA1 genes. Thus, the presence of two BoLA A genes, which may be expressed and functional in the bovine, as well as in sheep was confirmed. A large number of amino acids unique to products of DQA2 genes of bovine and ovine origin were identified when the predicted amino acid sequences for both species were compared, and most of the DQA2-specific residues were located in the alpha 1 domain and were conserved with respect to products of DQA1 genes of ruminants. Thus, several characteristics of the bovine DQA genes were found to differ from those of human and rodent genes, despite similarities in gene structure and in nucleotide sequence.

Structure-activity correlationship and strain specificity of polyoxometalates in anti-human immunodeficiency virus activity

The anti-human immunodeficiency virus (HIV) activity of polyoxometalates of representative structural families, such as Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich, was determined using two strains of HIV type 1 (HIV-1HTLV-IIIB and HIV-1SF-2H). The compounds were preferably selected to cover both polyoxotungstates and polyoxomolybdates in each structural family. In general, polyoxotungstates of Keggin, lacunary Keggin, trivacant Keggin, Keggin sandwich, Wells-Dawson and Wells-Dawson sandwich structures showed anti-HIV-1HTLVIIIB activity, whereas most compounds not included in these structural categories were inactive. Among the compounds with a potent anti-HIV-1HTLV-IIIB activity, those of Keggin and its closely related structural families (lacunary Keggin, trivacant Keggin and Keggin sandwich) inhibited the cytopathogenicity and syncytium formation caused by HIV-1SF-2 to a much higher extent compared with HIV-1HTLV-IIIB-related ones. The difference between the spectra of anti-HIV-1HTLV-IIIB activity and the specificity for HIV-1SF-2H might result from differential structural requirements in these functions.

[Clinical significance of late peak formation of creatine kinase in patients with acute anterior myocardial infarction after successful reperfusion]

Generally, the time from the onset of acute myocardial infarction (MI) to peak serum creatine kinase (CK) activity is short in patients with acute MI after successful reperfusion. However, in some patients peak CK is observed more than 16 hours after the onset of acute MI despite successful reperfusion. To elucidate the clinical characteristics of patients with late peak CK, CK activity was examined in 55 patients (mean age: 57.5 +/- 10.2 years) with initial acute anterior MI after successful reperfusion. All patients had coronary reflow (TIMI grade 3) within 6 hours after onset of acute MI and no subsequent reocclusion for at least 14 days. The patients were classified into two groups: group E, 41 patients with peak CK observed within 16 hours of onset of acute MI (mean 8.7 hours), and group L, 14 patients with peak CK observed after more than 16 hours (mean 18.7 hours). Although there were no significant differences in the time elapsed between the two groups, the mean peak CK was significantly lower in group L than in group E (2,179 +/- 861 vs 5,379 +/- 2,569 mU/ml, p < 0.01). Well-developed collateral supplies to the infarcted area before reperfusion were observed more frequently in group L (79% vs 24%, p < 0.01). The sum of ST elevation in all leads before reperfusion was lower in group L (12 +/- 7 vs 20 +/- 12 mm, p < 0.01) and additional ST elevation during reperfusion was not observed in group L (0% vs 56%, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the nucleoprotein of rabies virus in Escherichia coli and mapping of antigenic sites

Investigations were performed to delineate the antigenic sites I and IV of rabies virus nucleoprotein (N), the former of which is well conserved among the rabies and rabies-related viruses. The N cDNA of the RC-HL strain was inserted into an expression vector pET3a, with which the E. coli BL21(DE3) was transformed. Upon induction with isopropyl-1-thio-beta-D-galactoside, the transformants produced a protein with a size (56 k-Da) almost identical to that of the authentic N protein. The protein also reacted with a panel of our N protein-specific monoclonal antibodies (N-MAbs) including the antibodies against the antigenic sites I and IV. By using the cDNA, various deletion mutants were generated and expressed in E. coli to examine the reactivity of mutant proteins with N-MAbs by Western blot analysis. Deletion of the C-terminal 67 amino acid residues did not abolish their reactivity with any of the N-MAbs specific for the sites I and IV. When 91 residues or more were deleted from the C-terminus, however, the protein lost the reactivity, indicating that the antigenic sites I and IV are mapped to a small region which is comprised of at most 24 amino acid residues from positions 360 to 383. Comparison of the 24-amino acid sequence with the corresponding region of N protein of several other Lyssavirus strains suggests that the antigenic site I is mapped to positions 360 to 369.

Novel assay system favorable for the study of cell-to-cell transmission of HIV-1 and its application to the evaluation of anti-HIV drugs

The cell-to-cell transmission of human immunodeficiency virus type 1 (HIV-1) was studied using MOLT-4 cells chronically infected with a variant strain of HIV-1SF-2 (MOLT-4/HIV-1SF-2H) and CD4+ human lymphoid MT-4 cells. MOLT-4/HIV-1SF-2H cells produced less than 1 TCID50 infectious particles per day as determined by the cytopathogenicity in MT-4 cells. However, the expression of envelope glycoproteins gp120 and gp41 on the MOLT-4/HIV-1SF-2H cell membrane was satisfactory for syncytium formation with the uninfected MOLT-4 cells. When MOLT-4/HIV-1SF-2H and MT-4 cells were co-cultured, severe cytopathogenicity was observed in MT-4 cells without being accompanied by the formation of multi-nucleated cells. Thus, the system consisting of MOLT-4/HIV-1SF-2H and MT-4 cells is convenient for exclusive study of the mechanism of cell-to-cell transmission of HIV-1. Using various compounds, it was confirmed that cell-to-cell transmission required both gp120/gp41-CD4 binding and de novo DNA synthesis.

Molecular cloning and expression in Escherichia coli of bleomycin-resistance gene from a methicillin-resistant Staphylococcus aureus and its association with IS431 mec

A gene that confers bleomycin resistance was cloned from the chromosomal DNA of methicillin-resistant Staphylococcus aureus (MRSA) B-26 into the plasmid pUC18. It is of chromosomal origin rather than plasmid and exists in the chromosome making a cluster with the kanamycin-resistance gene. We found that the nucleotide sequence of the bleomycin-resistance gene from the chromosome of MRSA B-26 is identical to that from a staphylococcal plasmid, pUB110. The partial sequence of IS431mec was also found upstream from the DNA fragment containing the bleomycin- and kanamycin-resistance genes.

Effect of dimethylthiourea on chromium (VI)-induced DNA single-strand breaks in Chinese hamster V-79 cells

The effect of 1,3-dimethyl-2-thiourea (DMTU), a specific hydroxyl radical scavenger on chromate-induced DNA breaks, was studied using Chinese hamster V-79 cells. Incubation of cells with Na2CrO4 plus DMTU resulted in a small but significant decrease in cellular levels of the metal-caused DNA single-strand breaks. Electron spin resonance studies showed that DMTU did not affect the formation of chromium (V) complexes either in cells or in the reaction of Na2CrO4 with reduced glutathione in vitro, however, DMTU suppressed the generation of hydroxyl radicals in the reaction of hydrogen peroxide and chromium (V) in vitro. Thus, Na2CrO4-induced DNA breaks were inhibited by DMTU, possibly due to its ability to scavenge hydroxyl radicals. These and other previous studies indicated that the formation of hydroxyl radicals contribute to the induction of DNA breaks by Na2CrO4 in intact cells, but presumably is not the only mechanism involved.

Cloning and characterization of polyphenol oxidase cDNAs of Phytolacca americana

Two cDNA clones encoding polyphenol oxidases were isolated from a cDNA library constructed from a log-phase suspension culture of Phytolacca americana (pokeweed) producing betalains. The clones exhibit 93 and 86% sequence identity at the nucleotide and deduced amino acid levels, respectively. Both clones contain two copper-binding domains characterized by histidine-rich regions, which are found ubiquitously in all polyphenol oxidases/tyrosinases, and a putative third histidine-rich, copper-binding region, which is common to all plant polyphenol oxidases. One of the Phytolacca cDNA deduced amino acid sequences contains the ubiquitous transit peptide for all proteins targeted to the internal lumen of thylakoid membranes of plastids and is considered to be 98 residues in length based on a proposed sequence cleavage site motif. This would produce a processed peptide of approximately 54 kD. In addition to common features of transit peptides, it was found that an additional conserved region for polyphenol oxidases was located between the hydroxy amino acid-rich region and the thylakoid transfer domain. Spatial and temporal expression was investigated by northern blot analysis of total RNA from various organs of Phytolacca plants. Transcripts of the two clones were found to be 2.1 and 2.3 kb, respectively. Both transcripts were present only at substantial levels in ripening, betalain-containing fruit.

Overproduction of the bleomycin-binding proteins from bleomycin-producing Streptomyces verticillus and a methicillin-resistant Staphylococcus aureus in Escherichia coli and their immunological characterisation

The bleomycin-binding proteins designated BLMA and BLMS, which confer resistance to bleomycin (Bm), from Bm-producing Streptomyces verticillus ATCC15003 and a methicillin-resistant Staphylococcus aureus B-26, respectively, were overexpressed in Escherichia coli. The present study showed that both BLMA and BLMS quench the antibacterial activity of Bm by the binding to the drug. To immuno-characterize the Bm-binding proteins, we constructed a monoclonal antibody against BLMA. The antibody, designated 893-12, did not cross react to BLMS and another Bm-binding protein from tallysomycin-producing Streptoalloteichus hindustanus. Although the ability of Bm to cleavage DNA was eliminated by a binding of BLMA to Bm, as shown by Sugiyama et al. [Gene 151 (1994) 11-15], the Bm-induced DNA degradation was restored by pre-incubation of BLMA with the anti-BLMA monoclonal antibody.

Characterization of a Bombyx mori cDNA encoding a novel member of the attacin family of insect antibacterial proteins

A Bombyx mori cDNA was cloned that hybridized with Hyalophora cecropia attacin probe and its nucleotide sequence was determined. This cDNA consisted of 846 nucleotides and the deduced amino acid sequence showed that the cDNA encodes an attacin precursor protein. The putative mature protein of B. mori attacin had 70.4, 68.3 and 18.8% identity in amino acid sequences with that of H. cecropia acidic and basic attacins and Sarcophaga peregrina sarcotoxin IIA, respectively. B. mori and H. cecropia attacins and S. peregrina sarcotoxin IIA had two subdomains in each G domain, suggesting that common amino acid residues in the subdomains are conserved during evolution and plays an important role in the activity of the antibacterial proteins. Expression of B. mori attacin gene was rapidly induced by the injection of Escherichia coli cells into B. mori larvae and continued at least for 48 h mainly in fat bodies and hemocytes.

Sequence analysis of cDNA for the VP6 protein of group A avian rotavirus: a comparison with group A mammalian rotaviruses

cDNA corresponding to the genomic segment 6 of avian rotavirus strain PO-13, which has group A common and subgroup I antigens, but does not hybridize in Northern blots with RNA probes from group A mammalian rotaviruses, was cloned and sequenced. When the deduced amino acid sequence was compared between strain PO-13 and eight group A mammalian rotaviruses, the extent of homology ranged from 73-75%. An alignment of the amino acid sequences allowed us to identify three amino acids (Positions 120, 317 and 350) that may contribute to determining the subgroup epitopes. A phylogenetic tree constructed on the basis of nucleotide substitutions in the VP6 gene of nine rotaviruses strongly suggests that the avian rotavirus is an ancestral prototype of mammalian rotaviruses.

Natural habitats of Corynebacterium kutscheri in subclinically infected ICGN and DBA/2 strains of mice

Subclinically infected mice of ICGN and DBA/2 strains housed in a conventionally managed colony were examined to determine natural habitats of Corynebacterium kutscheri. At 5, 7, 9, 12 and 13 months after initial isolation of the organism from oral cavity and cecal contents of five ICGN mice, attempts were made to isolate C. kutscheri from 19 sites using a new selective medium, furazolidone-nalidixic acid-colimycin agar. From the initial survey to 13 months, C. kutscheri was isolated from 27 of 29 ICGN mice (93.1%) and 9 of 10 DBA/2 mice (90%). In contrast, antibody against C. kutscheri was detected in only 3 of 29 ICGN mice (10.3%). None of the mice manifested distinct clinical signs of infection, and only 1 ICGN mouse had macroscopic lesions such as hepatic abscess and large spleen. In 21 ICGN and 9 DBA/2 mice that harbored the organism without macroscopic lesions, the organisms were most frequently isolated from the oral cavity (ICGN:100%, DBA/2:66.7%), cecum (ICGN:95.2%, DBA/2:100%), and colon and rectum (ICGN:95.2%, DBA/2:100%). Remarkable differences between the two mouse strains were observed in colonization of the nasal cavity (ICGN:85.7%, DBA/2:0%) and trachea (ICGN:71.4%, DBA/2:33.3%). In mice of both strains, the organisms rarely colonized the lung, liver, and kidney. Mean numbers of organisms in the cecum, and colon and rectum ranged from 10(4.1) to 10(4.6) colony-forming units/g and were significantly higher in comparison with those in the small intestine (P < 0.01, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical significance of inverted T-waves during the acute phase of myocardial infarction in patients with myocardial reperfusion]

The relationship between the time course of inverted T-waves during the acute phase and infarct size and left ventricular (LV) function was studied in 46 patients (mean age: 57.3 +/- 9.7 years) with reperfused first anterior wall acute myocardial infarction (MI). All patients had coronary reflow within 6 hrs after the onset of MI and were without subsequent reocclusion for at least 14 days. The T-wave inverted progressively and rapidly with maximum depth between 26 and 60 hrs (mean time: 37.1 +/- 12.4 hrs). A significant correlation was found between the maximum T-wave depth (T-peak) in all patients and peak CPK, left ventricular ejection fraction (LVEF), regional wall motion, % abnormally contracting segment (%ACS), end-diastolic and end-systolic volume indices (EDVI,ESVI) at day 14 after the onset of MI (p < 0.05). T-wave inversion within 24 hrs after onset of MI was observed in 43 patients (93%). There were significant correlations between the depth of T-wave inversion occurring in patients 24 hrs after onset of MI (T24) and peak CPK, LVEF, regional wall motion, % ACS, EDVI, and ESVI at day 14 (p < 0.05). The sensitivity and specificity for patients with EDVI > 87.0 ml/m2 at day 14 increased by more than 20% over normal values, predicted by a T24 of 3.0 mm or less, were 94% and 93%, respectively. The sensitivity and specificity for patients with EF < 40% at day 14 predicted by a T24 of 3.0 mm or less, were 90% and 75%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural and subclinical Corynebacterium kutscheri infection in rats

Distribution of Corynebacterium kutscheri was determined in 41 rats housed in a conventionally managed colony that were infected naturally and subclinically. At 2, 5, 10, 20 and 25 months after initial isolation of C. kutscheri, attempts were made to isolate C. kutscheri from 17 sites, with a new selective medium, FNC agar. In total, the prevalence (97.6%) of C. kutscheri isolation was significantly (P < 0.001) higher than the frequency (70.7%) of antibody detection. None of the rats manifested any distinct clinical signs of disease and macroscopic lesions caused by C. kutscheri were not detected. In 40 rats with subclinical infection, the organisms were most frequently isolated from the oral cavity, esophagus, cecal contents, and colon and rectum (> 95.0%). The isolation rate was next highest in the trachea, submaxillary lymph nodes, and nasal cavity (47.5 to 52.5%). The organisms hardly colonized the lung, liver, and kidney. Mean numbers of organisms found in the esophagus, cecal contents, and colon and rectum ranged from 10(3.9) to 10(4.2) CFU/g, and were significantly (P < 0.05, P < 0.01) high in comparison with those in the lung. These results indicated that many healthy rats in the naturally infected colony harbored C. kutscheri, and the organisms colonized the oral cavity, esophagus, cecal contents, and colon and rectum most frequently.

Inhibitory effects of intravenous lansoprazole on gastric acid hypersecretion in patients with postoperative stress

The inhibitory effects of intravenous lansoprazole on gastric acid hypersecretion caused by stress after surgical invasion were studied in patients who underwent surgery under general anesthesia for gastrointestinal diseases. Patients in this study received either 15 mg or 30 mg of lansoprazole by slow intravenous injection twice daily for 3 days (six injections). The total number of patients studied was 82, with 41 patients in each group. Intragastric pH was measured every 8 h after the start of administration, and the inhibitory effects of intravenous lansoprazole on postoperative gastric acid secretion were evaluated using four grades: excellent, good, fair, and poor. In the 15-mg group, 65.8% (25 of 38 patients) were classified as good or excellent, and in the 30-mg group, 75.7% (28 of 37 patients) were good or excellent. No adverse effects directly attributable to the administration of lansoprazole were observed.

Colorimetrical rate assay for urinary dipeptidyl peptidase IV (DPPIV) activity using a new substrate

We synthesized a new substrate glycyl-L-proline 3,5-dibromo-4-hydroxyanilide (Gly-Pro-DBAP), for dipeptidyl peptidase IV (DPPIV). Its hydrolysis by DPPIV resulted in the formation of a chromophore, 2,6-dibromophenol-indo-p-xylenol, and its maximal absorption wavelength (600 nm) was longer than that of p-nitroaniline (415 nm) released from conventional substrate, glycyl-L-proline p-nitroanilide (Gly-Pro-pNA). We also established the rate assay for urinary DPPIV activity using Gly-Pro-DBAP. The optimum pH was between 8.5 and 9.0. The apparent Km was 1.1 mmol/1. The detectable range was 2.5-350 U/l. No changes in blank values occurred throughout the enzyme reaction in the optimum pH. Its value was also much lower than Gly-Pro-pNA. CVs for within-run and between-run were 1.1% (n = 10) and 3.0% (n = 10), respectively. Among tested peptidases, only DPPIV could hydrolyze Gly-Pro-DBAP. Among the protease inhibitors, only two, diprotin-A and phenylmethylsulfonyl fluoride (PMSA), could inhibit DPPIV activity. The present method did not interfere with urinary ingredients such as hemoglobin. The correlation between the present (y) and conventional (x) methods is presented by the equation y = 1.121x + 0.096 (r = 0.993). Thus the present method provides practical advantages over the conventional method for routine laboratory use.

Determining the optimal dose of lansoprazole injection by 24-hour intragastric pH monitoring

Two studies were performed on healthy adult males using 24-h intragastric pH monitoring to investigate the acid secretion inhibitory effects of the proton pump inhibitor lansoprazole in its injectable form (lansoprazole injection). In the first study (study 1), eight subjects received 30 mg once daily and 30 mg twice daily of lansoprazole injection by the crossover method. In the second study (study 2), 12 subjects received 15 and 30 mg twice daily of lansoprazole injection and 20 mg twice daily of a histamine H2-receptor antagonist using the crossover method. The results of study 1 showed that 30 mg once daily of lansoprazole injection was not able to achieve sufficient suppression of acid secretion, and the results of study 2 suggested that the effectiveness of the three treatment regimens studied in suppressing gastric acid secretion can be ranked as follows: lansoprazole 30 mg twice daily > lansoprazole 15 mg twice daily > H2-receptor antagonist 20 mg twice daily.

Characterisation by molecular cloning of two genes from Streptomyces verticillus encoding resistance to bleomycin

Extracts of a bleomycin (Bm)-producing Streptomyces verticillus ATCC15003 were found to possess an acetyltransferase activity which inactivates Bm in the presence of acetyl coenzyme A. DNA fragments of S. verticillus were introduced into S. lividans by cloning and transformants selected for resistance to Bm. Deletion mapping and subcloning of a 6-kb DNA fragment showed the presence of two resistance determinants, blmA and blmB. The acetyltransferase activity was encoded by blmB; nucleotide sequence analysis identified an ORF consisting of 301 amino acids (aa) proposed to be that of Bm acetyltransferase (Bat). S. lividans and Escherichia coli transformants harboring plasmids carrying blmB produced an acetyltransferase which modified and determined resistance to Bm and structurally related antibiotics; this resistance gene has potential as a selective marker in gene transfer studies. Nucleotide sequence analysis of blmA revealed an ORF encoding 122 aa that had significant sequence similarity to the gene encoding the Bm-binding protein (Shble) identified by Gatignol et al. [FEBS Lett. 230 (1988) 171-175] in Streptoalloteichus hindustanus, the tallysomycin-producer. The blmA gene was expressed in E. coli and the resulting protein, like the Shble protein, prevents in vitro Bm-induced DNA breakage.

Clinical evaluation of uniaxially oriented poly-L-lactide rod for fixation of experimental femoral diaphyseal fracture in immature cats

Transverse diaphyseal fractures of the femur were experimentally made in immature cats, and were fixed by an intramedullary pinning technique using an uniaxially oriented poly-L-lactide (PLLA) rod, a biodegradable polymer. The healing process was evaluated radiographically and histologically. Formation of bony callus was completed in 8 weeks, and cortical bony union followed. The remodeling process was then observed form 12 to 16 weeks. The healing process was almost the same as when a metallic implant was used. Abundant periosteal callus formation may be attributable to the lower elasticity of the PLLA rod compared with metallic implants. Since no other abnormalities such as growth deformities were detected, it was concluded that the combined use of a uniaxially oriented PLLA rod and an external splint is clinically useful for the repair of diaphyseal fractures in immature cats.

Oxygen scavengers in simple bone cysts

Simple bone cyst is a fluid-filled, cystic lesion that occurs in the metaphysis of the long bones of children and adolescents. The chemical characteristics of the cyst fluid of the simple bone cyst are similar to those of serum. The existence of the cyst fluid itself may be an obstacle to cyst healing, and, in part, this may be because the cyst fluid contains bone destructive factors. Oxygen-free radicals, which are cytotoxic and cause connective tissue damage, are known to be generated under ischemic conditions. Blockage to the drainage of interstitial fluid within the metaphysis has been suggested as the possible primary cause of simple bone cyst, thus causing an ischemic state in which free radicals are generated. The precise measurement of free radical levels is difficult to obtain because of their extremely short half-lives. High levels of oxygen-free radicals induce high levels of oxygen scavengers locally to protect cells from the harmful effects of the free radicals. Therefore, the activity of the oxygen scavengers, superoxide dismutase and catalase, was measured in the cyst fluid of 9 cases of simple bone cyst as an indicator of high oxygen-free radical content in the cyst. Serum from the patients with simple bone cyst and joint fluid from patients with osteoarthritis were used for comparison with the intracystic levels of oxygen scavengers. Superoxide dismutase activity was directly measured at room temperature using an electron spin resonance spin-trapping technique with 5,5'-dimethyl-1-pyrroline-N-oxide as a trapping agent.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of hepatotoxicity caused by mono-, di- and tributyltin compounds in mice

The in vivo induction of hepatotoxicity, as evaluated by the activity of ornithine carbamyl transferase in serum, was investigated in mice administered orally with the following three butyltin compounds: tributyltin chloride (TBTC), dibutyltin dichloride (DBTC) and monobutyltin trichloride (MBTC). The minimal concentrations of TBTC and DBTC that caused hepatotoxicity at 24 h after oral administration were 180 mumol and 60 mumol/kg, respectively, while MBTC did not induce liver injury even at 7000 mumol/kg. Additionally, when the administered doses were equivalent (180 mumol/kg), a time course (3-96 h) study revealed that the hepatotoxicity of TBTC and DBTC appeared at 24 and 12 h, respectively, but that MBTC showed no hepatotoxicity even at 96 h. The amounts of Sn excreted into urine for 4 days were 1.5 fold greater with TBTC than with DBTC treatment and were lowest in MBTC group. Similarly, the total liver Sn content was 2- to 5-fold greater in the TBTC group than in the DBTC group whereas the liver Sn content in the MBTC treatment showed the lowest value throughout the 3- to 96-h period. Thus, the non-hepatotoxicity of MBTC may be due either to low absorption through the digestive tract of mice or to the low levels of Sn in liver; however, the level of Sn in liver was not associated with the induction of hepatotoxicity by TBTC and DBTC.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effects of riboflavin and its derivatives against ischemic reperfused damage of rat heart

The effects of riboflavin and its derivatives such as FAD, FMN and lumichrome on the levels of high energy phosphate compounds (ATP and creatine phosphate) and intracellular pH in ischemic reperfused rat hearts were investigated using a Langendorff perfusion technique. 31P-NMR study showed a decrease in the levels of high energy phosphate compounds and pH values in myocardium after 30 min global ischemia and a slight recovery of these levels after a 30 min reperfusion following ischemia. However, in all the hearts perfused with riboflavin and its derivatives during ischemia-reperfusion, a marked recovery of high energy phosphate compounds and pH values were observed. In addition, the cardiac mitochondrial respiratory function was protected from ischemia-reperfusion injury. These results suggest that riboflavin, FAD, FMN, and lumichrome have a protective effect against ischemia-reperfusion injury to rat myocardium in vitro. It is assumed that these substances exert their effect directly in the extracellular space.