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Biomedical subjects

J Wan

Publications and source records attributed to J Wan.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cloning and characterization of the CYP2D1-binding protein, retinol dehydrogenase.

A CYP2D1-binding protein, 29 k-protein (p29), has been isolated and its N-terminal amino acid sequence has been reported (Ohishi et al. (1993) Biochim. Biophys. Acta 1158, 227-236). In this study, p29 cDNA was isolated by PCR with oligonucleotide probes designed from the N-terminal amino acid sequence and p29 was found to be a microsomal retinol dehydrogenase, a member of the short-chain alcohol dehydrogenase family which metabolize hydroxysteroids and prostaglandins. CYP2D1 and p29 were expressed in Saccharomyces cerevisiae to characterize these proteins. CYP2D1 had an absorption maximum at 448 nm in a CO-reduced form. Expressed p29 in yeast cells was detected with anti-p29 antibody. Solubilized CYP2D1 and p29 from yeast microsomes were mixed and applied to an anti-CYP2D1 antibody-binding column. Both proteins were retained in the column and eluted with glycine buffer (pH 2.8). However, when applied alone, p29 was not retained in the column. The findings indicated that CYP2D1 bound tightly with p29. Catalytic activities of p29 expressed in yeast were investigated. p29 had retinal reductase activity in the presence of NADPH. Addition of CYP2D1 and NADPH-P450 reductase increased the retinal reductase activity of p29. These findings suggest that the complex of CYP2D1, p29, and NADPH-P450 reductase has an important role in the metabolism of retinoids.

Alcohol Oxidoreductases↗
PubMed1998

Oxidized cholesterol in oxidized low density lipoprotein may be responsible for the inhibition of LPS-induced nitric oxide production in macrophages.

Previous work has shown that oxidized low density lipoprotein (Ox-LDL) inhibited lipopolysacchride (LPS)-induced nitric oxide (NO) production in macrophages. In this paper, the role of different components of Ox-LDL in the inhibitory effect was studied by measuring nitrite in media. Ox-LDL inhibited LPS-induced NO production in macrophage cell line J774.A1. When compared with Ox-LDL, native and acetylated LDL had a lesser effect on NO production. Pre-clearance of lipid hydroperoxides (LOOH) in Ox-LDL and removal of soluble thiobarbituric acid reactive substances (TBARS) in Ox-LDL solution by dialysis had no influence on the inhibitory effect of Ox-LDL. The protein moiety of Ox-LDL had no effect on NO production, but the lipid moiety inhibited NO production to about the same extent as intact Ox-LDL. Linoleic acid and phosphatidylcholine, the main components of LDL lipid, whether oxidized separately or together, had no effect on NO production. However, if linoleic acid and cholesterol oxidized together, there was very strong inhibition of NO production. Cholesterol oxidized alone also had some inhibitory effect. These results suggest that oxidized cholesterol in Ox-LDL might be responsible for the inhibition of NO production in macrophages.

Animals↗
PubMed1998

Renal growth characteristics in children born with multicystic dysplastic kidneys.

OBJECTIVES: To report on the growth characteristics of the affected and contralateral kidneys in children born with multicystic dysplastic kidneys (MCDKs). METHODS: Thirty-three patients were enrolled from 1970 to 1995: 23 were initially managed nonoperatively (mean follow-up 3.39 years), and 10 underwent nephrectomy. Patients underwent radionuclide renal imaging and contrast voiding cystography. Serial ultrasonography was used to obtain measurements of the affected and contralateral kidneys. Blood pressure measurements and serum creatinine levels were available in some patients. RESULTS: Among the 23 nonoperative patients, the affected MCDK involuted in 4 patients during a mean follow-up of 4.5 years at a rate of 1.02 cm/yr (24% annually); 7 kidneys decreased in size at a mean rate of 0.38 cm/yr (5.8% annually); 6 grew at a mean rate of 1.16 cm/yr (9.9% annually); 1 kidney did not change in size; and 5 children were lost to follow-up. The mean size of the contralateral kidneys at birth was 5.3 cm, 2 standard deviations larger than normal. Over time, this relative hypertrophy was maintained at a growth rate of 0.89 cm/yr (18.5% annually). Two patients who had undergone nephrectomy also had serial postoperative ultrasonic renal measurements, and contralateral growth was 0.61 cm/yr (12.16% annually). All but 1 patient had normal blood pressure measurements and serum creatinine levels. CONCLUSIONS: Most MCDKs involute or decrease in size over time, although this may take many years. Contralateral hypertrophy is seen at birth and is maintained during childhood growth, regardless of whether the affected kidney is removed. There is no associated hypertension or malignancy when the dysplastic kidney is left in place.

Follow-Up Studies↗
PubMed1998

The effect of essential oils of basil on the growth of Aeromonas hydrophila and Pseudomonas fluorescens.

Basil essential oils, including basil sweet linalool (BSL) and basil methyl chavicol (BMC), were screened for antimicrobial activity against a range of Gram-positive and Gram-negative bacteria, yeasts and moulds using an agar well diffusion method. Both essential oils showed antimicrobial activity against most of the micro-organisms examined except Clostridium sporogenes, Flavimonas oryzihabitans, and three species of Pseudomonas. The minimum inhibitory concentration (MIC) of BMC against Aeromonas hydrophila and Pseudomonas fluorescens in TSYE broth (as determined using an indirect impedance method) was 0.125 and 2% (v/v), respectively; the former was not greatly affected by the increase of challenge inoculum from 10(3) to 10(6) cfu ml-1. Results with resting cells demonstrated that BMC was bactericidal to both Aer. hydrophila and Ps. fluorescens. The growth of Aer. hydrophila in filter-sterilized lettuce extract was completely inhibited by 0.1% (v/v) BMC whereas that of Ps. fluorescens was not significantly affected by 1% (v/v) BMC. In addition, the effectiveness of washing fresh lettuce with 0.1 or 1% (v/v) BMC on survival of natural microbial flora was comparable with that effected by 125 ppm chlorine.

Acyclic Monoterpenes↗
PubMed1998

The synergistic preservative effects of the essential oils of sweet basil (Ocimum basilicum L.) against acid-tolerant food microflora.

Essential oils extracted by hydrodistillation from five different varieties of Ocimum basilicum L. plants (Anise, Bush, Cinnamon, Dark Opal and a commercial sample of dried basil) were examined for antimicrobial activity against a wide range of foodborne Gram-positive and -negative bacteria, yeasts and moulds by an agar well diffusion method. All five essential oils of basil showed antimicrobial activity against most of the organisms tested with the exception of Flavimonas oryzihabitans and Pseudomonas species. The inhibitory effect of Anise oil, in comparison with mixtures of the predominant components of pure linalool and methyl chavicol, against the acid-tolerant organisms, Lactobacillus curvatus and Saccharomyces cerevisiae, was examined in broth by an indirect impedance method. Synergistic effects between Anise oil, low pH (pH 4.2) and salt (5% NaCl) were determined. The antimicrobial effect of Anise oil was also assessed in a tomato juice medium by direct viable count, showing that the growth of Lact. curvatus and S. cerevisiae was completely inhibited by 0.1% and 1% Anise oil, respectively. The results of the current study indicate the need for further investigations to understand the antimicrobial effects of basil oils in the presence of other food ingredients and preservation parameters.

Acyclic Monoterpenes↗
PubMed1998

The comparative effects of nitrogen and oxygen on the microflora of beef steaks in carbon dioxide-containing modified atmosphere vacuum skin-packaging (MA-VSP) systems.

The effects of 80% oxygen-20% carbon dioxide (O2-CO2) and 80% nitrogen-20% carbon dioxide (N2-CO2) atmospheres were compared with respect to the microbial and sensory characteristics of vacuum skin-packaged grain-fed beef steaks stored at -1 and 4 degrees C. In both N2-CO2 and O2-CO2 atmospheres, lactobacilli were predominant over Brochothrix, pseudomonads, enterobacteria and yeasts and moulds. The results of the current investigation showed that the O2-CO2 atmospheres did not yield total viable counts in excess of 10(5) cfu cm-2 on beef steaks after 4 weeks of storage. However, the sensory analysis and thiobarbituric acid (TBA) values (as a measure of oxidative rancidity) of the products were unacceptable at this time. In contrast, the N2-CO2 atmospheres yielded maximum total viable counts of approximately 10(7) cfu cm-2 and the sensory analysis and TBA values of the product were judged to be acceptable after 4 weeks of storage at -1 degree C. These results indicate that sensory effects of the product were influenced to a greater extent by the chemical effects of high concentration of O2 on rancidity than by the high levels of lactobacilli.

Animals↗
PubMed1998

In vitro interactions between a potyvirus-encoded, genome-linked protein and RNA-dependent RNA polymerase.

Recent studies have shown that potyvirus VPg/ proteinases and RNA-dependent RNA polymerases are capable of protein-protein interactions in yeast cells. We have extended these studies in vitro. We found that tobacco vein mottling virus (TVMV) VPg is retained on glutathione-Sepharose matrices if co-incubated with a glutathione S-transferase (GST)-NIb fusion protein, but not with GST, which is suggestive of a direct physical interaction between these two proteins. However, a mutation in the VPg (Y1860S) that eliminates virus infectivity and the interaction in yeast cells had little effect on the in vitro interaction. We also found that the TVMV VPg and NIa proteins are capable of stimulating the polymerase activity of the NIb protein. Since this stimulatory activity is retained when the proteinase domain of the NIa is removed, we conclude that the VPg is the moiety responsible for the stimulation of polymerase activity. As with the interaction revealed by co-purification, the Y1860S mutation had little or no effect on the stimulation of polymerase activity. Moreover, the VPg was able to stimulate a mutant NIb with an altered 'GDD' motif. Our studies thus provide two lines of evidence indicative of in vitro interactions between the TVMV VPg and NIb proteins.

Amino Acid Sequence↗
PubMed1998

A protein-bound polysaccharide synergistic with lipopolysaccharide induces nitric oxide release and antioxidant enzyme activities in mouse peritoneal macrophages.

The aim of this study is to examine whether polysaccharide krestin, a protein-bound polysaccharide, can prevent the progression of atherosclerosis and lipoperoxidative injury caused by oxidatively modified low density lipoprotein (Ox-LDL) to macrophages. The alterations of GSHPx (glutathione peroxidase), SOD (superoxide dismutase) activity and NO (nitric oxide) release in PSK-treated mouse peritoneal macrophages, and the effect of LPS on them were investigated. With peritoneal injection of PSK, the following were observed in the mouse peritoneal macrophages: 1) an increase in SeGSHPx activity, 2) elevation in non-SeGSHPx and SOD activity; 3) the enzyme activities were further improved by addition of lipopolysaccharide (LPS); and 4) much NO was found to be released by PSK-treated mouse peritoneal macrophages stimulated by LPS.

Animals↗
PubMed1998

The effect of tert-butyl hydroperoxide on peritoneal macrophages and the protective effect of protein-bound polysaccharide administered intraperitoneally and orally.

Our previous studies have shown that a protein-bound polysaccharide, polysaccharide krestin (PSK), can protect macrophages from lipoperoxidative injury induced by tert-butyl hydroperoxide (tbOOH) and oxidatively modified low density lipoprotein (O-LDL). PSK was administered intraperitoneally to mice, and the peritoneal macrophages harvested were used as an experimental model. PSK does not reveal any protective effect on macrophages injured by tbOOH when incubated in vitro. In order to elucidate its mode of action, in the present study, the protective effects of PSK were further investigated using morphological changes and viability as indices. It was shown that, compared with the non-PSK group, the viability of macrophages was much higher in the PSK group, and the morphological changes in the PSK group were much less than those in the non-PSK group. The protective effect of PSK administered intraperitoneally and orally on macrophages injured by tbOOH was comparable. Furthermore, the serum of the PSK treated mice had the same protective effect.

Administration, Oral↗
PubMed1998

Oxidative and malondialdehyde modification of low-density lipoprotein: a comparative study of binding and degradation by macrophages and endothelial cells.

Comparative study of oxidatively modified low-density lipoprotein (Ox-LDL) and malondialdehyde-modified low-density lipoprotein (MDA-LDL) is important for further understanding the biological properties of Ox-LDL, such as its toxic effects, immunogenicity and multiplicity of scavenger receptor binding. In this study, the characteristics of Ox-LDL and MDA-LDL binding and degradation were compared. The results show that when their degree of modification (as determined by relative electrophoretic mobility) was similar, the binding and degradation of Ox-LDL by the macrophage cell line P388D1 were greater than those of MDA-LDL. The binding and degradation of Ox-LDL by macrophages and human umbilical vein endothelial cells increased with the degree of modification. In addition, Ox-LDL or MDA-LDL could competitively inhibit binding of labelled Ox-LDL or labelled MDA-LDL to their respective macrophage receptors, and could partially inhibit each other.

Animals↗
PubMed1998

[A multiple variable analysis about the risk factors of breast cancer in women].

A comprehensive investigation to the risk factors of breast cancer was carried out in 146 pairs of women subjects, with the method of 1:1 matched case-control study, and of logistic regression analysis and principal component analysis. As a result, a regression equation which includes 5 independent variables has been established by logistic regression analysis; Ten principal components were extracted from 22 risk factors of breast cancer through principal component analysis, and the cumulative contribution of variances of the 10 principal components is 64.8%. The result combining the mono-factor analysis and the multiple variables analysis indicated that the principal risk factors of breast cancer are cadre occupation, the age of primiparity and late marriage, more intake of salted meat and sausage, passive smoking, having the history of family tumor, of breast benign tumor, and of the mastadenitis; but the more number of giving births, longer period of time of lactation, more vegetable intake, and taking more vitamin may have preventive effect for breast cancer.

Adult↗
PubMed1998

[Development and clinical application of a brain stereotactic endoscope].

OBJECTIVE: To investigate the feasibility, indications and advantages of endoscopic surgery for brain neoplasms and hypertensive haematoma. METHOD: A self-designed brain endoscope with a wide working channel was used for resection of deep-seated brain neoplasm or other cranial cerebral operations of 30 patients operated on endoscopically, 13 had intracranial tumor, 15 hypertensive intracerebral haematoma, 1 thalamic abscess, and 1 cysticercosis. RESULT: Total removal of tumor was achieved in 4 patients, subtotal or major partial removal in 7, and biopsy in 2. Completely evacuation of haematoma was achieved in 7 patients and partial evacuation in 8 (over 80%). The abscess was evacuated and the solitary cysticercosis focus was removed with our endoscope. No obvious postoperative complications were noted. CONCLUSION: The advantages of stereotactic endoscopy for deep-seated brain neoplasm include accurate intraoperative localization, minimal invasion, good recovery, no or a few complications. The indications for this intervention are small lesions deep in the brain parenchyma with well-defined boundary and light vascularity. Intracerebral haematoma can be evacuated under direct vision endoscopically, without damage to the haematoma cavity wall.

Brain Neoplasms↗
PubMed1998

Molecular characterization of multiresistant strains of Salmonella typhi from South Asia isolated in Ontario, Canada.

Two hundred and fourteen isolates of Salmonella typhi submitted to our laboratory between 1992 and 1996 were tested for susceptibility to 20 antimicrobial agents. Forty-eight of the 214 isolates (22.4%), recovered from individuals who had travelled in South Asia, were multiresistant. Forty-four of the 48 isolates were resistant to ampicillin, chloramphenicol, tetracycline, streptomycin, sulfamethoxazole, trimethoprim, cotrimoxazole, ticarcillin, and piperacillin; the other four isolates were resistant to four to six agents. Forty-two of the multiresistant isolates belonged to Vi phage type E1, two isolates from the Punjab State belonged to phage type A, another from the Punjab State belonged to phage type E3, one isolate from Pakistan belonged to type M1, and one isolate from India belonged to type J1. Plasmids from 45 of 48 isolates showed a temperature-sensitive mechanism of transfer to Escherichia coli K-12 strains, characteristic of H1 incompatibility group plasmids. The majority of plasmids had an estimated molecular weight of 120 MDa and encoded both citrate utilization and mercury resistance. Plasmids from three isolates had an estimated molecular weight of 112-115 MDa; one of these isolates encoded citrate utilization but not mercury resistance. Analysis of isolates by pulsed-field gel electrophoresis after digestion with XbaI and SpeI indicated that the majority of multiresistant isolates shared a common restriction profile, while four isolates had unique patterns.

Adolescent↗
PubMed1997

Expression of four rat CYP2D isoforms in Saccharomyces cerevisiae and their catalytic specificity.

We cloned four cDNAs belonging to the CYP2D subfamily to express these enzymes in yeast cells and to compare their catalytic activities simultaneously. Three are believed to be alleles of CYP2D1, 2D2, and 2D3, respectively, based on high nucleotide sequence similarity, while CYP2D4 had both sequences of CYP2D4 and CYP2D18. Expression plasmids carrying CYP2D cDNAs were transformed into Saccharomyces cerevisiae. Typical P450 CO-difference spectra with absorbance maximum at 448 nm were recorded with microsomal preparations from the yeast cells expressing the four CYP2D forms. A catalytic study of these CYP2D forms was done with debrisoquine, bufuralol, and lidocaine. CYP2D2 had the highest debrisoquine 4-hydroxylation (2.2 nmol/min/nmol P450) activity, similar to that (2.2 nmol/min/nmol) of human CYP2D6 expressed in yeast cells. CYP2D3 had high lidocaine N-deethylation (43 nmol/min/nmol P450) activity, and both CYP2D3 and 2D2 exhibited high lidocaine 3-hydroxylation (2.4 and 1.6 nmol/min/nmol P450, respectively) activity. Bufuralol 1'-hydroxylation catalytic capabilities were comparable among the four isoforms. The activity of CYP2D1 was relatively low toward the three substrates (debrisoquine, 0.091; bufuralol, 1.5; lidocaine 3-hydroxylation, 0.019; lidocaine N-deethylation, 2.8 nmol/min/nmol P450). These findings indicate that debrisoquine, a typical substrate for CYP2D forms, was mainly metabolized by CYP2D2 but not CYP2D1 in rat liver and that the CYP2D forms have different substrate specificity.

Animals↗
PubMed1997

Enuresis and common voiding abnormalities.

Voiding problems, and in particular nocturnal enuresis, can usually be evaluated and managed without resorting to complex procedures or invasive tests. A good history with attention to toilet habits and the possible presence of infection can help distinguish patients who may have significant organic pathologic conditions who require further investigation. Wetting alarms are effective with a low recidivism rate but are noisy. DDAVP is effective, works rapidly, and is discrete but has a higher recidivism rate. Treatment is aimed at correcting any poor toilet habits and using the appropriate alarm device or medication.

Behavior Therapy↗
PubMed1997

Detection of bacteriocins of lactic acid bacteria isolated from foods and comparison with pediocin and nisin.

A total of 663,533 colonies from 72 dairy and meat sources showed a detection rate of 0.2% for bacteriocin producers using direct plating techniques. A further 83,000 colonies from 40 fish and vegetable sources showed a detection rate of 3.4% for bacteriocin producers using selective enrichment procedures. A collection of seven purified isolates showing a different host spectrum of bacteriocin activity and with the ability to produce bacteriocins in broth culture were compared with nisin and pediocin (with respect to their inhibitory activity, determined by the critical dilution method), against various indicator bacteria in agar and broth. The sensitivity of Listeria species to various bacteriocins was influenced by the agar and broth test systems used. A Lactobacillus curvatus strain was found to be the most suitable indicator for quantitating antimicrobial effects of all the bacteriocins investigated in both agar and broth test systems. The bacteriocin-producing isolates were characterized by biochemical reactions and DNA restriction enzyme profiles and taxonomic identification revealed species of Lactobacillus, Carnobacterium and Lactococcus assigned on the basis of 16S rDNA sequences.

Agar↗