Antihepatotoxic activity of icariin, a major constituent of Epimedium koreanum

In an attempt to identify compounds with antihepatotoxic activity, carbon tetrachloride-induced cytotoxicity in primary cultured rat hepatocytes has been adopted as a screening system. Using this screening system, an antihepatotoxic compound from the aerial parts of Epimedium koreanum has been isolated. This compound, icariin, is a flavonol glycoside. Its antihepatotoxic activity was first evaluated by measuring the release of glutamic pyruvic transaminase and sorbitol dehydrogenase from CCl4-intoxicated rat hepatocytes into the culture medium. Icariin significantly reduced the level of glutamic pyruvic transaminase and sorbitol dehydrogenase released resulting in a 76% protection from toxicity at concentration ranges from 1 microM to 20 microM. The antihepatotoxic activity of icariin was also estimated by the determination of total cytochrome P-450 content and glutathione-S-transferase activity in the CCl4-intoxicated hepatocytes.

Brush border membrane aminopeptidase-N in the midgut of the gypsy moth serves as the receptor for the CryIA(c) delta-endotoxin of Bacillus thuringiensis

Aminopeptidase-N (AP-N) was purified from gypsy moth (Lymantria dispar, L.) brush border membrane vesicles (BBMV) proteins by mono-Q chromatography and Superdex-75 gel filtration in the presence of the zwitterionic detergent, CHAPS, using FPLC. The purified AP-N, identified by its enzymatic activity, had an apparent size of 100 kDa, and was identified as the unique Bacillus thuringiensis insecticidal toxin, CryIA(c), binding protein. AP-N clearly displayed strong binding to CryIA(c), exhibiting little or no binding to CryIA(a) or CryIA(b), and showing no binding for the coleopteran-specific toxin, CryIIIA. Protein blots of the BBMV proteins probed with biotin-labeled and 125I-labeled insecticidal proteins revealed that CryIAc binds only to 120 kDa protein which is a slightly larger size in comparison to purified AP-N. Antibodies raised against the gypsy moth AP-N demonstrated that the purified AP-N and the 120 kDa CryIA(c) binding protein of total BBMV proteins are antigenically identical.

Domain III exchanges of Bacillus thuringiensis CryIA toxins affect binding to different gypsy moth midgut receptors

Aminopeptidase-N, purified from gypsy moth (Lymantria dispar L.) brush border membrane vesicles, exhibited specific binding to CryIAc toxin but not to CryIAa toxin. CryIAa-CryIAc hybrid toxins were used to localize the aminopeptidase-N binding region on CryIAc. Slot blot assays and ligand blot experiments demonstrated that the hybrid toxins which have the residues 451 to 623, comprising essentially domain III, from CryIAc toxin exhibited strong binding to purified aminopeptidase-N and 120 kDa brush border membrane protein. In contrast, the hybrid toxins which have the residues 451 to 623 from CryIAa toxin failed to bind to aminopeptidase-N, but did bind to another receptor, a 210 kDa protein. This is the first direct evidence that domain III is involved in receptor binding and the first to demonstrate that domain III substitutions direct the binding of these toxins to different gypsy moth midgut receptors.

Resistance to Bacillus thuringiensis CryIA delta-endotoxins in a laboratory-selected Heliothis virescens strain is related to receptor alteration

The Bacillus thuringiensis toxin-binding properties of midgut epithelial cells from two strains of Heliothis virescens were compared. One H. virescens strains (YHD2) which was selected against CryIAc toxin had over 10,000-fold resistance to CryIAc toxin relative to the susceptible strain and was cross-resistant to CryIAa and CryIAb. The second H. virescens strain (YDK) was susceptible to these toxins in the order CryIAc > CryIAb > CryIAa. Receptor-binding properties of CryIAa, CryIAb, and CryIAc toxins were compared between the susceptible and resistant strains. Saturation and competition-binding experiments were performed with brush border membrane vesicles prepared from midguts of the susceptible and resistant insects and 125I-labeled toxins. In the susceptible strain, saturable, specific, and high-affinity binding of all three toxins was observed. The relative binding-site concentration was directly correlated with toxicity (CryIAc > CryIAb > CryIAa). In the resistant strains, the binding affinities of CryIAb and CryIAc were similar to that observed with the susceptible strain and ony minor differences in binding-site concentration (Bmax) were observed. The major difference between the two strains was the total lack of binding of CryIAa toxin to the brush border membrane vesicles of the resistant strain. Heterologous competition-binding experiments and ligand blot analysis supported the hypothesis that there were multiple binding sites for the toxins. On the basis of results of the present study, we propose that alterations in binding proteins shared by all three toxins are a major factor in resistance. This suggests that not all receptors of CryIAc might be involved in toxic function.

Metabolic effects of troglitazone on fat-induced insulin resistance in the rat

Troglitazone is a new orally active hypoglycemic agent that has been shown to ameliorate insulin resistance and hyperinsulinemia in both diabetic animal models and non-insulin-dependent diabetes mellitus (NIDDM) subjects. To determine whether this drug could prevent the development of diet-induced insulin resistance and related abnormalities, we studied its effect on insulin resistance induced by high-fat feeding in rats. Normal male Sprague-Dawley rats were fed a high-fat diet for 3 weeks with and without troglitazone as a food mixture (0.2%) or were fed normal chow. In vivo insulin action was measured using a euglycemic-hyperinsulinemic clamp at two different insulin infusion rates, 4 (submaximal stimulation) and 40 (maximal stimulation) mU/kg/min. Fat feeding markedly reduced the submaximal glucose disposal rate ([GDR], 26.4 +/- 1.3 v 37.5 +/- 1.4 mg/kg/min, P < .01) and maximal GDR (55.9 +/- 1.3 v 64.5 +/- 1.3 mg/kg/min, P < 0.5), reduced the suppressibility of submaximal hepatic glucose production ([HGP], 3.2 +/- 0.9 v 1.5 +/- 0.5 mg/kg/min, P < .05), and resulted in hyperlipidemia. Troglitazone treatment did not affect any of these parameters. Insulin resistance induced by fat feeding is the first experimental model in which troglitazone failed to correct or partially correct the insulin resistance.

Binding kinetics of monoclonal antibody using antigen-beta-galactosidase hybrid protein: application to measurement of peptide antigenicity

A simple method for determination of binding kinetics of a solid-phase antibody using antigen-beta-galactosidase hybrid protein was evaluated. To minimize conformational change of the antigen binding site of the antibody when directly binding to a microtiter plate, the microtiter plate was precoated with protein A. The binding and free antigen concentrations were directly obtained from the beta-galactosidase activity. This method can be used for analyses of the equilibrium dissociation constant (KD), and the association (Kass) and dissociation (Kdiss) rate constants. Peptide antigenicity was also analyzed by competitive ELISA using this method. Since both antigen-beta-galactosidase and the peptide used are localized in the fluid-phase, the proper affinity constant (KA) of the peptide can be estimated from the KD value of the antigen-beta-galactosidase-antibody interaction, and from the IC50 value of the peptide.

Correlations among height, leg length and arm span in growing Korean children

A cross-sectional study was performed to find out if any specific correlations exist among height, leg length and arm span in growing Korean children. Height, leg length and arm span were measured in 10,322 healthy children (4740 males and 5582 females). Computed ratios of leg length to height, leg length to arm span and arm span to height for the 3rd, 25th, 50th, 75th and 97th percentiles were made. It was found that the ratios of leg length to height, leg length to arm span, and arm span to height were bigger in taller children in the same age group than the shorter ones in both sexes. All the ratios were bigger in older children in the same percentile than the younger ones in both sexes, showing that the growth rates of leg length and arm span were bigger than that of height in general. However, growth of leg length is faster in shorter children than in taller children until the onset of puberty, after which growth of leg length in taller children is faster than in shorter children. The first and most rapid growth of leg length is seen from birth to 2 years, the second growth spurt is seen during the pubertal period. An exceptional increment in leg length between ages from 10 to 15 is also noted in taller children. After puberty, arm span grows faster than height until 17 years of age in the tallest male child, and taller children have longer arm span than height, while arm span in the shortest children never exceeds height.

Acute effects of troglitazone on in vivo insulin action in normal rats

Troglitazone is a newly developed antidiabetic agent that shows hypoglycemic effects in insulin-resistant animal models and non-insulin-dependent diabetic humans. To determine whether this drug could affect in vivo insulin action acutely, insulin-stimulated glucose utilization was measured with the euglycemic glucose clamp technique before, during, and after troglitazone infusion (20 micrograms/min) in normal rats. Hepatic glucose production (HGP) was measured with a tracer-dilution technique (D-[3-3H]-glucose). At 18-pmol/kg/min insulin infusion rate, steady-state glucose disposal rate (GDR) was significantly increased during troglitazone infusion versus control vehicle infusion (162 +/- 6.1 v 142.3 +/- 4.4 mumol/kg/min, P < .02). The glucose infusion rate (GIR) required to maintain euglycemia increased shortly (10 to 20 minutes) after initiation of troglitazone infusion and was significantly greater until 30 minutes after cessation of the drug versus the vehicle infusion. At 9-pmol/kg/min insulin infusion rate, HGP was significantly decreased during troglitazone infusion as compared with control vehicle infusion (21.7 +/- 3.5 v 39.5 +/- 3.7 mumol/kg/min, P < .02). These results indicate that troglitazone can acutely increase in vivo insulin action in normal rats, and some possible mechanisms are discussed.

PCDD/DFs and coplanar PCBs in sediment and fish samples from the Er-Jen river in Taiwan

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and coplanar polychlorinated biphenyls (Co-PCBs) have been determined in sediment and fish samples from the Er-Jen river in Taiwan. Sediment samples collected near the incineration site show TEQ of PCDD/DFs ranging from 14 pg/g to 14200 pg/g and 2,3,7,8-tetrachlorodibenzo-p-dioxins equivalents (TCDD-EQ) of Co-PCBs ranging from 9 pg/g to 1030 pg/g. The fish samples show TEQ of PCDD/DFs ranging from 37 pg/g to 2084 pg/g and TCDD-EQ of Co-PCBs ranging from 12 pg/g to 120 pg/g. Possible PCDD/DFs sources are discharged PCBs, open-air incineration activities, and pentachlorophenol. PCB#126 was found to degrade more readily than PCB#77. TCDD-EQ of Co-PCBs could be estimated from the total concentration of PCBs. A daily intake value of 28 pg/kg/day to 450 pg/kg/day was estimated when consuming fish caught from the Er-Jen river.

Insulin restores fatty acid composition earlier in liver microsomes than erythrocyte membranes in streptozotocin-induced diabetic rats

Alterations of fatty acid composition have been observed in a number of tissues in both experimental and human diabetes. Suppression of delta 6 desaturase in the liver, a key enzyme of fatty acid desaturation, has been reported to be responsible for these phenomena. We measured the fatty acid composition of the liver and the erythrocytes, and examined delta 6 desaturase activities to compare the effect of short-term insulin therapy on the tissues with and without delta 6 desaturase, ie., the liver and the erythrocytes using streptozotocin (STZ)-induced diabetic rats. Linoleic (P < 0.05), palmitic (P < 0.01) and docosahexaenoic (DHA) acid (P < 0.01) were higher and arachidonic (P < 0.01) and oleic acid (P < 0.01) were lower in the liver microsomes of diabetic rats when compared to those in control rats. These alterations were partly reversed with insulin treatment. In the erythrocyte membrane, linoleic (P < 0.01) and stearic acid (P < 0.05) were higher, and palmitic (P < 0.05), palmitoleic (P < 0.01), and arachidonic acid (P < 0.01) were lower in diabetic rats. In contrast to the case of the liver microsomes, however, these alterations were persistently observed after 48 h of insulin treatment. The activities of delta 6 desaturase in diabetic rats were 68% of those of controls (P < 0.05), and increased to 119% of controls after insulin treatment. These results show that insulin restores the fatty acid composition earlier in the liver microsome than in the erythrocyte membrane in STZ-induced diabetic rats. The erythrocyte membrane would not be suitable for the investigation dealing with rapid changes of fatty acid composition.

The effects of milrinone on platelets in patients undergoing cardiac surgery

Although amrinone produces thrombocytopenia, no information is available regarding the acute effects of milrinone on platelets. Therefore, we evaluated the effects of milrinone on platelet number and function in cardiac surgical patients. Twenty-seven patients were studied during cardiac surgery requiring cardiopulmonary bypass (CPB). Patients were randomized to receive no milrinone (n = 10), or milrinone (n = 17) at a loading dose of 50-75 micrograms/kg in the CPB circuit followed by 0.5-0.75 micrograms.kg-1.min-1 for 12-24 h. Bleeding times and blood samples for coagulation studies were obtained prior to induction, and at 2 and 24 h after CPB. In both groups, platelet counts decreased significantly from the baseline at 2 and 24 h after CPB, and bleeding time increased significantly from the baseline at 2 and 24 h after CPB. No significant thromboelastoplasty (TEG) changes were observed in either group, and there were no significant differences in platelet aggregation or chest tube drainage between the groups. Acute milrinone administration did not cause significant changes in platelet number or function in patients undergoing cardiac operations requiring CPB, beyond the usual adverse effects of cardiac surgery and CPB.

Moyamoya disease in Malaysia: two documented cases

Moyamoya disease is a rare cause of young strokes. The definitive diagnosis of moyamayo disease is made by cerebral angiography. We report two cases of moyamoya disease in Malaysia.

Taxol and related compounds in Korean native yews (Taxus cuspidata)

The concentrations of taxol and related compounds in the bark and needles of Taxus cuspidata grown on Mt. Jiri, Mt. Sobaek, and Cheju Island, and T. cuspidata var. latifolia on Ullung Island in Korea were determined by high performance liquid chromatography (HPLC). The taxane content significantly varied with the location and plant part. The taxol content in the bark of native yews from Mt. Jiri and Mt. Sobaek was high when compared to that reported for Pacific yew (T. brevifolia), whereas bark from trees on Cheju and Ullung islands contained a much lower level. Surprisingly, the needles from Cheju and Ullung islands contained a much higher level of taxol (0.022% and 0.0173%, respectively) than those of intermountain locations (0.0058% to 0.0085%), on the basis of dry weight. The bark and needles of T. cuspidata var. latifolia on Ullung Island also contained relatively high concentrations of 10-deacetylbaccatin III, 0.0497% and 0.0545%, respectively, and indicated that environmental factors may affect the quantity. Taxol in the needles was confirmed by electrospray mass spectrometry. These results suggest that foliage from yew trees growing in their natural habitats on Cheju and Ullung islands may provide a renewable source for taxol.

An adverse property of a familial ALS-linked SOD1 mutation causes motor neuron disease characterized by vacuolar degeneration of mitochondria

Mutations in Cu/Zn superoxide dismutase (SOD1) cause a subset of cases of familial amyotrophic lateral sclerosis. Four lines of mice accumulating one of these mutant proteins (G37R) develop severe, progressive motor neuron disease. At lower levels of mutant accumulation, pathology is restricted to lower motor neurons, whereas higher levels cause more severe abnormalities and affect a variety of other neuronal populations. The most obvious cellular abnormality is the presence in axons and dendrites of membrane-bounded vacuoles, which appear to be derived from degenerating mitochondria. Since multiple lines of mice expressing wild-type human SOD1 at similar and higher levels do not show disease, the disease in mice expressing the G37R mutant SOD1 must arise from the acquisition of an adverse property by the mutant enzyme, rather than elevation or loss of SOD1 activity.

Single amino acid changes in domain II of Bacillus thuringiensis CryIAb delta-endotoxin affect irreversible binding to Manduca sexta midgut membrane vesicles

Deletion of amino acid residues 370 to 375 (D2) and single alanine substitutions between residues 371 and 375 (FNIGI) of lepidopteran-active Bacillus thuringiensis CryIAb delta-endotoxin were constructed by site-directed mutagenesis techniques. All mutants, except that with the I-to-A change at position 373 (I373A), produced delta-endotoxin as CryIAb and were stable upon activation either by Manduca sexta gut enzymes or by trypsin. Mutants D2, F371A, and G374A lost most of the toxicity (400 times less) for M. sexta larvae, whereas N372A and I375A were only 2 times less toxic than CryIAb. The results of homologous and heterologous competition binding assays to M. sexta midgut brush border membrane vesicles (BBMV) revealed that the binding curves for all mutant toxins were similar to those for the wild-type toxin. However, a significant difference in irreversible binding was observed between the toxic (CryIAb, N372A, and I375A) and less-toxic (D2, F371A, and G374A) proteins. Only 20 to 25% of bound, radiolabeled CryIAb, N372A, and I375A toxins was dissociated from BBMV, whereas about 50 to 55% of the less-toxic mutants, D2, F371A, and G374A, was dissociated from their binding sites by the addition of excess nonlabeled ligand. Voltage clamping experiments provided further evidence that the insecticidal property (inhibition of short-circuit current across the M. sexta midgut) was directly correlated to irreversible interaction of the toxin with the BBMV. We have also shown that CryIAb and mutant toxins recognize 210- and 120-kDa peptides in ligand blotting. Our results imply that mutations in residues 370 to 375 of domain II of CrylAb do not affect overall binding but do affect the irreversible association of the toxin to the midgut columnar epithelial cells of M. sexta.

Detection and identification of aquatic birnaviruses by PCR assay

A reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed for the detection and identification of aquatic birnaviruses. The four sets of primers (PrA, PrB, PrC, and PrD) that we used are specific for regions of cDNA coded by genome segment A of aquatic birnaviruses. PrA identifies a large fragment (1,180 bp) within the pVP2-coding region, and PrB identifies a 524-bp fragment within the sequence amplified by PrA. Primer set PrC frames a genome fragment (339 bp) within the NS-VP3-coding region, and PrD identifies a 174-bp sequence within the fragment identified by PrC. PrB and PrD amplified cDNAs from all nine recognized serotypes of aquatic birnavirus serogroup A as well as the N1 isolate that may represent a 10th serotype. These results indicate that these three primer sequences are highly conserved and can be used in PCR assays for group identification of these viruses. PrA routinely produced amplification products from eight serotypes but exhibited variable results with one serotype, and primer PrC identified 6 of the 11 virus isolates tested. The qualitative sensitivity of the RT-PCR assay was evaluated by comparison of the results with those of cell culture isolation assays. With the exception of one sample, the RT-PCR assay with primer PrD was as accurate as cell culture isolation for detecting virus in kidney and spleen tissues from naturally infected, asymptomatic carrier fish. These results indicate that the RT-PCR assay can be a rapid and reliable substitute for cell culture methods for the detection of aquatic birnaviruses.

Superoxide dismutase 1 subunits with mutations linked to familial amyotrophic lateral sclerosis do not affect wild-type subunit function

Mutations in superoxide dismutase 1 (SOD1) have been linked to familial amyotrophic lateral sclerosis, a dominantly inherited motor neuron disorder of midlife. Because SOD1 is a homodimeric enzyme, dimerization of mutant and wild-type SOD1 subunits could dominantly alter the activity, stability, or localization of wild-type SOD1 subunits. To explore these possibilities, we used transient and stable gene transfection to express high levels of either of two mutant human SOD1 subunits in the presence of limited levels of wild-type mouse and/or human SOD1 subunits. Although both mutant subunits displayed diminished half-lives and free radical scavenging activities, their presence caused no change in the half-life or activity of wild-type SOD1 subunits. Our data indicate that mutant subunits do not dominantly affect the function of wild-type SOD1 subunits. These findings, together with observations that many mutant SOD1 subunits retain significant stability and activity, suggest that motor neuron damage in familial amyotrophic lateral sclerosis is caused by the acquisition of injurious properties by mutant SOD1 subunits.

22 genes from chromosome 17q21: cloning, sequencing, and characterization of mutations in breast cancer families and tumors

In our effort to identify BRCA1, 22 genes were cloned from a 1-Mb region of chromosome 17q21 defined by meiotic recombinants in families with inherited breast and/or ovarian cancer. Subsequent discovery of another meiotic recombinant narrowed the region to approximately 650 kb. Genes were cloned from fibroblast and ovarian cDNA libraries by direct screening with YACs and cosmids. The more than 400 cDNA clones so identified were mapped to cosmids, YACs, and P1 clones and to a chromosome 17 somatic panel informative for the BRCA1 region. Clones that mapped back to the region were hybridized to each other and consolidated into clusters reflecting 22 genes. Ten genes were known human genes, 5 were human homologs of known genes, and 7 were novel. Each gene was sequenced, compared to genes in the databases to find homologies, and analyzed for mutations in BRCA1-linked families and tumors. Eight mutations were found in tumors or families and not in controls. In the gene encoding alpha-N-acetylglucosaminidase, approximately 100 kb proximal to the 650-kb linked region, somatic nonsense, missense, and splice junction mutations occurred in 3 breast tumors, but not in these patients' germline DNA nor in controls. In an ets-related oncogene in the linked region, a missense mutation cosegregated with breast cancer in one family and was not observed in controls. In a human homolog of a yeast pre-mRNA splicing factor, 3 different mutations cosegregated with breast cancer in 3 families and were not observed in controls. In these and the other genes in the region, 36 polymorphic variants were observed in both cases and controls.

The search for BRCA1

BRCA1, a gene predisposing to breast and ovarian cancer, was mapped to chromosome 17q21 by linkage analysis. Loss of heterozygosity in breast and ovarian tumors from BRCA1-linked patients always involved loss of wild-type alleles from chromosome 17q21, suggesting that BRCA1 acts as a tumor suppressor gene. Meiotic recombination in linked families constrained the BRCA1 region to an estimated physical size of 650 kilobases. Twenty-two candidate genes were isolated by screening complementary DNA libraries with yeast artificial chromosomes and cosmids from the critical region. Of these, 8 were known human genes, 7 were homologues of genes identified in other species, and 7 encoded novel transcripts. Each gene were sequenced and analyzed for variation, revealing 44 variants, including two missense mutations in two genes which segregated with breast cancer and were not found in controls. However, no frame-shift, nonsense, or regulatory mutations were found.

Metabolic effects of troglitazone on fructose-induced insulin resistance in the rat

Troglitazone is a new orally active hypoglycemic agent that has been shown to reduce insulin resistance and hyperinsulinemia in both diabetic animal models and non-insulin-dependent diabetes mellitus (NIDDM) subjects. To determine whether this drug could prevent the development of fructose-induced insulin resistance and related abnormalities, we studied the effects of troglitazone on the insulin resistance induced by fructose feeding in rats. Normal male Sprague-Dawley rats were fed a high-fructose diet for 3 weeks with and without troglitazone as a food admixture (0.2%) or were fed normal chow to serve as a control group. In vivo insulin resistnace was measured by the euglycemic hyperinsulinemic clamp technique at two different insulin infusion rates, 29 (submaximal stimulation) and 290 (maximal stimulation) pmol.kg-1.min-1. Fructose feeding markedly reduced submaximal glucose disposal rate (GDR) (113.8 +/- 8.3 vs. 176.0 +/- 5.6 mumol.kg-1.min-1, P < 0.05) and maximal GDR (255.9 +/- 5.6 vs. 313.6 +/- 10.5 mumol.kg-1.min-1, P < 0.05), reduced the suppressibility of submaximal hepatic glucose production (HGP; 45.5 +/- 5.0 vs. 11.7 +/- 5.0 mumol.kg-1.min-1, P < 0.05), and resulted in hypertriglyceridemia and hypertension. Troglitazone treatment completely restored the GDR (submaximal 158.2 +/- 5.6, maximal 305.3 +/- 6.1 mumol.kg-1.min-1) and submaximal HGP (9.4 +/- 2.8 mumol.kg-1.min-1) to control levels and also normalized the elevated plasma triglyceride concentration and systolic blood pressure levels in fructose-fed rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and regional mapping of 110 chromosome 22 STSs

As part of a larger effort to create a complete physical map of the human genome, we have developed 110 new STSs specific for human chromosome 22. Clones isolated and sequenced from chromosome 22-enriched libraries provided a source of primers. These STSs were localized to regions of chromosome 22 using a panel of somatic cell hybrids. In building a refined physical map of chromosome 22, this set of STSs should provide a substantial backbone.