Biomedical subjects

B H Lee

Publications and source records attributed to B H Lee.

At least 109 records · Page 6Linked to original sources

PubMed1999

Cloning of fish enzymes and other fish protein genes.

Fish metabolism needs special enzymes that have maximum activity at very different conditions than their mammalian counterparts. Due to the differences in activity, these enzymes, especially cold-adapted proteases, could be used advantageously for the production of some foods. In addition to the enzymes, this review describes some other unique fish polypeptides such as antifreeze proteins, fluorescent proteins, antitumor peptides, antibiotics, and hormones, that have already been cloned and used in food processing, genetic engineering, medicine, and aquaculture. Recombinant DNA technology, which allows these biological molecules to be cloned and overexpressed in microorganisms is also described, highlighting innovative applications. The expected impact of cloning fish proteins in different fields of technology is discussed.

Animals↗

PubMed1999

Characterization of angiotensin II antagonism displayed by SK-1080, a novel nonpeptide AT1-receptor antagonist.

The pharmacologic profile of SK-1080, a nonpeptide AT1-selective angiotensin-receptor antagonist, was investigated by receptor-binding studies, functional in vitro assays with rabbit and rat aorta, and in vivo experiments in pithed rats. SK-1080 inhibited the specific binding of [125I]-[Sar1, Ile8]-angiotensin II to human recombinant AT1 receptor with a 12-fold greater potency than losartan [median inhibitory concentration (IC50): 1.01 and 12.3 nM, respectively], but it did not inhibit the binding of [125I]-CGP 42112A to human recombinant AT2 receptor (IC50: >10 microM for both). The Hill coefficient for the competition curve of SK-1080 against AT1 receptor was not significantly different from unity (0.96). Scatchard analysis showed that SK-1080 interacted with human recombinant AT1 receptor in a competitive manner, as with losartan. In functional studies with rat and rabbit aorta, SK-1080 competitively inhibited the contractile response to angiotensin II (pKB values: 9.97 and 9.51, respectively) with 15-25% decrease in the maximal contractile responses, unlike losartan, which showed competitive antagonism without any change in the maximal contractile responses to angiotensin II (pA2 values, 8.02 and 7.59, respectively). In pithed rats, SK-1080 (i.v.) induced a nonparallel right shift in the dose-pressor response curve to angiotensin II (ID50, 0.07 mg/kg) with a dose-dependent reduction in the maximal responses; this antagonistic effect was approximately 25 times more potent than losartan (ID50, 1.74 mg/kg), which showed competitive antagonism. SK-1080 did not alter the responses induced by other agonists such as norepinephrine, KCI, and vasopressin in isolated rabbit aorta and pithed rats. These results suggest that SK-1080 is a highly potent AT1-selective angiotensin II-receptor antagonist with a mode of insurmountable antagonism.

Angiotensin II↗

PubMed1999

In vivo pharmacologic profile of SK-1080, an orally active nonpeptide AT1-receptor antagonist.

The pharmacologic profile of SK-1080, a newly synthesized AT1-receptor antagonist, was evaluated in conscious normotensive rats, conscious renally (RHRs) and spontaneously (SHRs) hypertensive rats, and conscious furosemide-treated beagle dogs. In angiotensin II-challenged normotensive rats, orally administered SK-1080 had no agonistic effect and dose-dependently inhibited the pressor response to angiotensin II with a slightly weaker potency (ID50: 1.12 and 0.47 mg/kg, respectively), but with a more rapid onset of action than losartan (time to Emax, 30 min and 6 h, respectively). In RHRs, orally given SK-1080 produced a dose-dependent and long-lasting (>24 h) antihypertensive effect with a potency similar to that of losartan (ED20, 5.06 and 3.36 mg/kg, respectively). Intravenously administered SK-1080 exerted a very highly potent antihypertensive effect (ED20, 0.06 mg/kg), thus indicating a poor oral bioavailability in rats. On repeated dosing for 21 days in SHRs, SK-1080 significantly reduced blood pressure without inducing tachycardia and tolerance throughout the dosing period. On repeated dosing, the antihypertensive effect gradually increased from days 1 to 7 (Emax on day 7, 15.0 and 19.7% at 10 and 30 mg/kg, respectively) and remained at a significant level on days 14 and 21. In furosemide-treated dogs, orally given SK-1080 produced a dose-dependent and long-lasting (>8 h) antihypertensive effect with a rapid onset of action (time to Emax, 1-1.5 h) and 10-fold greater potency than losartan (ED20, 0.72 and 8.13 mg/kg, respectively). In furosemide-treated dogs, SK-1080 showed a good oral bioavailability, unlike that in RHRs. These results suggest that SK-1080 is a potent, orally active AT1-receptor antagonist useful for the treatment of hypertension.

Administration, Oral↗

PubMed1999

Bacterial production of D-erythroascorbic acid and L-ascorbic acid through functional expression of Saccharomyces cerevisiae D-arabinono-1,4-lactone oxidase in Escherichia coli.

D-Arabinono-1,4-lactone oxidase, which catalyzes the terminal step in the biosynthesis of D-erythroascorbic acid in Saccharomyces cerevisiae, was functionally expressed in Escherichia coli inherently lacking the enzyme. The recombinant E. coli strain expressing the enzyme could overproduce D-erythroascorbic acid and L-ascorbic acid when supplied with D-arabinono-1,4-lactone and L-galactono-1,4-lactone, respectively.

Ascorbic Acid↗

PubMed1999

Pharmacological characterization of KR-30988, a novel non-peptide AT1 receptor antagonist, in rat, rabbit and dog.

The pharmacological profile of KR-30988, a non-peptide AT1-selective angiotensin receptor antagonist, has been investigated by use of a variety of experimental models in-vitro and in-vivo. KR-30988 inhibited the specific binding of [125I][Sar1, Ile8]-angiotensin II to the recombinant AT1 receptor from man with a potency similar to that of losartan (IC50 values, the concentrations of drugs displacing 50% of specific binding, 13.6 and 12.3 nM, respectively), but did not inhibit the binding of [125I]CGP 42112A to recombinant AT2 receptor from man (IC50 >10 microM for both drugs). Scatchard analysis showed that KR-30988 interacted competitively with recombinant AT1 receptor from man in the same manner as losartan. In functional studies with rat and rabbit aorta, KR-30988 noncompetitively inhibited the contractile response to angiotensin II (pD2, = -log EC50 (where EC50 is the dose resulting in 50% of a reference contraction), 8.64 and 7.73, respectively) with a 20-85% decrease in the maximum contractile responses, unlike losartan. In pithed rats intravenous KR-30988 resulted in a non-parallel shift to the right of the dose-pressor response curve to angiotensin II (ID50 value, the dose inhibiting the pressor response to angiotensin II by 50%, 0.09 mg kg(-1)) with a dose-dependent reduction in the maximum responses; in this antagonistic effect KR-30988 was 20 times (approx.) more potent than losartan (ID50 1-74 mg kg(-1)). In conscious renal hypertensive rats oral administration of KR-30988 produced a dose-dependent and long-lasting (>24 h) anti-hypertensive effect; the potency was six times that of losartan (ED30 values, the dose reducing mean arterial blood pressure by 30 mmHg, 0.48 and 2.97 mg kg(-1), respectively). In conscious furosemide-treated dogs oral administration of KR-30988 produced a dose-dependent and long-lasting (>8 h) hypotensive effect with a rapid onset of action (time to Emax, the maximum effect, 1-2 h); KR-30988 was eight times more potent than losartan (ED20, the dose reducing mean arterial blood pressure by 20 mm Hg, 1.04 and 7.96 mg kg(-1), respectively). These results suggest that KR-30988 is a potent, orally active selective AT1 receptor antagonist with a mode of insurmountable antagonism.

Angiotensin I↗

PubMed1999

Proposing sequences for peptides derived from whey fermentation with potential bioactive sites.

In fed-batch fermentation by Kluyveromyces marxianus var. marxianus, whey-soluble proteins were converted into oligopeptides. To assess whether bioactive peptides could be produced during whey fermentation, K. marxianus was cultured in batch in deproteinized media containing 5 or 15% (wt/vol) dehydrated whey for 20 h and then was in fed-batch mode for 50 h. After harvesting the biomass (25,000 x g, 15 min), at 6-h intervals, the wort was analyzed to determine protein consumption and oligopeptide production by HPLC. The proteins in the wort showed an oscillatory degradation with a constant increase in the production of oligopeptides. Four major peaks were collected and were analyzed by API mass spectroscopy. Sequences of fermented peptides were compared with sequences of known bioactive peptides. On the basis of their molecular weights, two amino acid sequences were proposed. The presence of sites containing the peptide sequence of beta-lactorphin (YLLF) suggests that these oligopeptides may have antihypertensive properties.

Amino Acid Sequence↗

PubMed1999

Purification and identification of potentially bioactive peptides from enzyme-modified cheese.

Antihypertensive peptides inhibiting angiotensin I-converting enzyme have been isolated from enzymatic hydrolysates of various food materials, but no information is available on the isolation of antihypertensive peptides from enzyme-modified cheese. In this study, several bioactive peptides, mainly potential antihypertensive peptides from enzyme-modified cheese prepared by commercial and Lactobacillus casei enzymes, were purified and identified. Enzyme-modified cheese samples were prepared by combination of Neutrase (1883.0 U/ml), L. casei enzymes (amino peptidase activity 86.4 leucine aminopeptidase U/g), and Debitrase (22.0 leucine aminopeptidase U/g). The water-soluble fractions of the enzyme-modified cheeses that were prepared by different enzymes were subjected to reverse-phase HPLC on a Delta Pak C18 column. Each peak was purified on the same column using a binary gradient. One peak from the Neutrase digest, five peaks from the Neutrase-Debitrase digest, and two peaks from the Neutrase-Lactobacillus enzyme digest were purified and identified by API mass spectrometry. On the basis of their molecular masses, amino acid sequences of purified peptides were identified. beta-Casomorphin with a sequence like that of beta-casein (YPFPGPI f 60-66) was found after the Neutrase digest. All of the peptides purified from the digests with combination of Neutrase and Debitrase or Neutrase and L. casei enzymes contained active sites in their sequences. The presence of sites containing potential antihypertensive peptides suggests that the purified peptides may have antihypertensive properties. Thus, the enzyme-modified cheese process, mainly designed to produce flavor ingredients, may simultaneously produce bioactive peptides, which are considered to be of physiological importance.

Amino Acid Sequence↗

PubMed1999

The efficacy of 0.2% brimonidine for preventing intraocular pressure rise following argon laser trabeculoplasty.

Brimonidine tartrate of 0.5% was identified as the most effective and safe dose for acute intraocular pressure (IOP) lowering. The efficacy of brimonidine tartrate 0.2% in preventing IOP elevation after an argon laser trabeculoplasty (ALT) was evaluated. Eighty patients were selected for a randomized, prospective study. Each patient was assigned to one of four treatment regimens: (1) brimonidine before and after ALT(B/B), (2) brimonidine before and placebo after ALT(B/P), (3) placebo before and brimonidine after ALT(P/B), (4) placebo before and after ALT(P/P). IOP elevation of 5 mmHg or greater occurred in 3.3% (2/60) of brimonidine-treated patients and in 30% (6/20) of placebo-treated patients. There was a mean decrease of IOP from baseline during the first 3 hours after ALT in all brimonidine-treated groups (7.1 +/- 3.4, 6.2 +/- 4.4, 3.5 +/- 2.9 mmHg for the B/B, B/P, P/B groups), but no change of mean IOP in the Placebo-treated group. Only one drop of brimonidine tartrate of 0.2% installed either before or after ALT was sufficient to prevent post-ALT IOP spike and minimize the undesired systemic adverse effects that two drop installation can produce.

Adrenergic alpha-Agonists↗

PubMed1999

Solid mesenchymal hamartoma of the liver in adult.

This paper presents an unusual solid mesenchymal hamartoma of the liver (MHL) in adult. A well defined solid mass in the left lobe of the liver was found in a 57-year-old female. Preoperative radiologic examinations demonstrated solid mass with multifocal calcifications abutting the gallbladder. By light microscopy, the lesion was composed of dense fibrous stroma with hyalinization, bile ducts and thick-walled vessels without hepatocytes. The solid and hyalinized mesenchymal component would suggest an unusual degenerative change representing a burnt-out MHL.

Female↗

PubMed1999

Preventive effects of a mixed disulphide from dithiocarbamate and N-acetylcysteine on the genotoxicity of N-nitrosodiethylamine.

A mixed disulphide model compound, S-(N,N-diethyldithiocarbamoyl)-N-acetylcysteine (AC-DDTC), prepared from diethyldithiocarbamate and N-acetylcysteine, was investigated for protective effects against the genotoxicity of the environmental carcinogen N-nitrosodiethylamine (NDEA). AC-DDTC was found to be a potent inhibitor of genotoxicity induced by NDEA. The mutagenicity of NDEA to Salmonella typhimurium was inhibited by 70% at 3.2 micromol AC-DDTC per plate and the effect was dose-dependent. In the chromosome aberration assay, NDEA elicited a significant increase in the number of aberrant cells. Pretreatment with AC-DDTC suppressed the chromosome-damaging effect of NDEA. The micronucleus-inducing capacity of NDEA was reduced by 32% by treatment with AC-DDTC at 1.5 mmol kg(-1). These results suggest that AC-DDTC might have a role to play in reducing the risk of cancer induced by NDEA.

Acetylcysteine↗

PubMed1999

The effect of continuous ambulatory peritoneal dialysis on change in serum leptin.

OBJECTIVE: Elevated serum leptin can contribute to anorexia and poor nutrition in patients with chronic renal failure, because leptin is elevated in chronic renal failure patients with or without dialysis, especially in chronic ambulatory peritoneal dialysis (CAPD) patients. The aim of this study was to find whether leptin can be removed by peritoneal dialysis (PD) and to analyze factors that can affect serum leptin after start of CAPD by observing the change in serum leptin shortly after start of CAPD and its correlation with body mass index (BMI), with serum insulin, and with residual renal function. DESIGN: Twenty patients who started CAPD during the observation period were studied. Serum leptin was measured by radioimmunoassay before start of CAPD, 3-5 days after start of CAPD, and 1 month and 3 months after start of CAPD. Simultaneously, body weight, serum insulin, and residual renal function were measured. To compensate for the circardian rhythm of leptin, removal of leptin was assessed by measuring dialysate leptin divided by average serum leptin before and after a peritoneal equilibration test (PET). RESULTS: Leptin was eliminated by PD with a dialysate-to-serum ratio of 0.16+/-0.07, which was comparable to removal of beta2-microglobulin (0.14+/-0.06). The mean serum leptin concentrations did not decrease after 3-5 days of CAPD (8.4+/-13.1 ng/mL-->11.9+/-18.0 ng/mL) despite its removal by PD, and levels increased markedly to 189% of basal serum leptin 1 month after start of PD and to 260% of basal serum leptin 3 months after start of PD. Correlation coefficients (Spearman's rho) between change of serum leptin and change of BMI, of serum insulin, of glomerular filtration rate (average of urine creatinine clearance and urine urea clearance) were 0.267 (p > 0.05, n = 20), 0.441 (p > 0.05, n = 16), 0.706 (p > 0.05, n = 8) respectively. CONCLUSION: Leptin is removed by peritoneal dialysis. Serum leptin did not decrease in 5 days after the start of PD despite its removal by PD, but increased markedly thereafter, within 3 months after start of PD. We could not find a significant correlation between the change in leptin and the change in BMI. Factors other than fat-mass gain can stimulate leptin increase shortly after start of PD.

Adipose Tissue↗

PubMed1999

The effect of dialysate dwell on gastric emptying time in patients on continuous ambulatory peritoneal dialysis.

METHODS AND PATIENTS: We evaluated gastric emptying time (GET) with a technetium (Tc) 99m-sulfur colloid gastric emptying scan in 11 patients on continuous ambulatory peritoneal dialysis (CAPD) (6 males, 5 females) and in 14 controls. We investigated the effect of dialysate dwell on GET by studying the subjects twice: once without dialysate in the abdomen (drained) and once with 2 L of dialysate in the abdomen (full). We also investigated the relationship between body surface area (BSA) and delayed gastric emptying. RESULTS: (1) The mean gastric emptying rate in 120 minutes in patients on CAPD when drained (67.8%+/-13.4%) was not different from that in controls (65.4%+/-8.6%). (2) The mean gastric emptying rate in 120 minutes in patients on CAPD when full was significantly slower than that when drained (55.6%+/-14.6% versus 67.8%+/-13.4%, p < 0.05). In four of the 11 patients (36.4%), gastric emptying was extremely delayed from normal to abnormal range when full. (3) The BSA of patients who had extremely delayed GET from normal to abnormal range was smaller than that of patients who had minimal delayed or unchanged GET when full (1.5+/-0.11 m2 versus 1.74+/-0.22 m2). CONCLUSION: This study showed that patients on CAPD had normal gastric emptying when drained, and that gastric emptying was delayed by dialysate dwell, especially in patients who has less than 1.5 m2 of body surface area. Therefore, we suggest that, based on adequacy, intermittent nocturnal peritoneal dialysis or a small volume of dialysate be considered for patients with small body surface area.

Dialysis Solutions↗

PubMed1998

Regulation of fibronectin gene expression by cyclic AMP and phorbol myristate acetate in HT-1080 human fibrosarcoma cells.

We studied the regulation of fibronectin (FN) gene expression by cAMP and phorbol-12-myristate-13-acetate (PMA) in HT-1080 human fibrosarcoma cells. Dibutyryl cAMP increased FN synthesis and mRNA levels, while PMA inhibited the cAMP-induced FN synthesis. In transient transfection assays, cAMP increased FN promoter activity, while PMA paradoxically enhanced the cAMP-induced promoter activity. Stable transfection experiments, however, showed that neither cAMP or PMA alone nor together affected FN promoter activity. These results suggest that PMA antagonizes the cAMP-induced FN gene expression and that both the action of cAMP and the inhibition of its action by PMA may occur at the posttranscriptional level in HT-1080 cells.

Blotting, Northern↗

PubMed1998

D-arabinose dehydrogenase and its gene from Saccharomyces cerevisiae.

D-Arabinose dehydrogenase was purified 843-fold from the cytosolic fraction of Saccharomyces cerevisiae with a recovery of 9%. The purified enzyme gave two bands with a molecular mass of 40 and 39 kDa on SDS-PAGE. The native enzyme had a molecular mass of 74 kDa as estimated by Sephacryl S-200 chromatography. Therefore, this enzyme was considered to be a heterodimer. The purified enzyme exhibited maximum activity at pH 10.0 and around 30 degrees C. The enzyme catalysed the oxidation of D-arabinose, L-xylose, L-fucose and L-galactose in the presence of NADP+. The apparent Km values at pH 10.0 with 50 microM NADP+ for D-arabinose, L-xylose, L-fucose, and L-galactose were 161, 24, 98 and 180 mM, respectively. The pH profile of Vmax and kcat/Km showed one ionisable groups around pH 8.3. D-Erythroascorbic acid was formed in vitro from D-arabinose by D-arabinose dehydrogenase and D-arabinono-1,4-lactone oxidase. The N-terminal amino acid sequence of the heavy subunit was Ser-Thr-Glu-Asn-Ile-Val-Glu-Asn-Met-Leu-His-Pro-Lys-Thr-. The N-terminus of the light subunit was blocked. The obtained peptide sequence was identical to the translational product of an unknown open reading frame, YBR149W, in chromosome II of S. cerevisiae. When compared with the translational product of this open reading frame, the peptide sequence was identical to the amino acid sequences of residues 7 to 20. The first six amino acids of this open reading frame were lost in protein sequence, which may be modified post-translationally. The heavy subunit was composed of 344 amino acid residues and its deduced amino acid sequence contained the motifs I, II, and III of aldo-keto reductase and also leucine zipper motif. This enzyme is the first heterodimeric protein of aldo-keto reductase family. In the deletion mutant of this gene, D-arabinose dehydrogenase activity and D-erythroascorbic acid were not detected.

Alcohol Oxidoreductases↗

PubMed1998

Anthelmintic beta-hydroxyketoamides (BKAs).

We have prepared several anthelmintic coumarins based on the beta-hydroxyketoamide (BKA) template and have shown that this template remains valid over a wide range of changes to the coumarin moiety allowing for the inclusion of carbocyclic, bicyclic, and heterocyclic rings.

Animals↗

PubMed1998

C24 and C25 substituted marcfortine A derivatives.

The dioxepinoindole ring found in marcfortine A (1) is unique among natural products. In order to determine the importance of the substitution pattern of the C24-C25 olefin, we synthesized a variety of analogs at these positions. With the exception of compound 5, none of these compounds exhibited any anthelmintic activity.

Animals↗

PubMed1998

In vitro chromosome aberration assay using human bronchial epithelial cells.

The determination of chromosome aberrations (CA) in Chinese hamster lung fibroblast (CHL) cells was compared with that in normal human bronchial epithelial (BEAS-2B) cells, which upon adenovirus infection were reported to possess carcinogen metabolizing capacities similar to polycyclic aromatic hydrocarbons. CHL and BEAS-2B cells were treated with increasing concentrations of benzo[a]pyrene (BaP) or N-nitrosodiethylamine (NDEA). In BEAS-2B cells, BaP, at a concentration of 50 microg/ml, produced a significant increase in the CA frequency, while NDEA did not markedly alter the number of aberrations in the absence of S9 mixture. The CHL cells exposed to BaP and NDEA in the presence of S9 mixture responded as anticipated with a 30% and 14% frequency of CA observed in the BaP (50 microg/ml) and NDEA (1000 microg/ml) treated cells, respectively. The results of this study show that the CA assay using human cell line with intrinsic metabolic activation system, such as BEAS-2B cells, may be a useful model for predicting human clastogens and carcinogens.

Animals↗

PubMed1998

Inhibition of electric eel acetylcholinesterase by porphin compounds.

Synthetic porphin compounds have been found to be reversible inhibitors of acetylcholinesterase from electric eel with Ki values of microM range. It seems that the number and position of fluorine on the phenyl ring and metal of an inhibitor play an important role for binding of an inhibitor to the enzyme active site.

Acetylcholinesterase↗