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Biomedical subjects

S Feng

Publications and source records attributed to S Feng.

228 records · Page 13Linked to original sources
PubMedDate not supplied

Ischemic preconditioning improves rat kidney graft function after severe ischemia/reperfusion injury.

UNLABELLED: Ischemic preconditioning (IP) has been shown to ameliorate renal ischemia reperfusion injury. Using a rat kidney transplantation model we determined if IP improves graft function after prolonged cold storage. MATERIALS AND METHODS: Syngeneic rat kidneys were divided into two groups. Prior to 42 hours of cold storage in UW and transplantation, one group (n = 10) received IP (15 minutes of warm ischemia/10 minutes of reperfusion), whereas another group (n = 10) received no treatment. Early graft function and 1-week recipient survival were assessed. RESULTS: Recipient survival was not significantly different between groups [70% (IP) vs 40% (non-IP); P = .28]. IP treatment led to a quicker recovery of renal function. On PODs 3 and 6, serum creatinine levels in the IP group were significantly lower compared with the untreated group. In conclusion, one cycle of IP (15/10) accelerates recovery of renal graft function after severe ischemia reperfusion injury. This simple treatment modality may improve outcomes of renal transplants with prolonged cold storage.

Animals↗
PubMedDate not supplied

Characterization of a 30-kDa Borrelia burgdorferi substrate-binding protein homologue.

A Borrelia burgdorferi chromosomal gene encodes a 30-kDa antigen (P30) that has considerable homology with periplasmic substrate-binding proteins of Gram-negative bacteria, and is recognized by antibodies in sera from a subset of patients with Lyme disease and from B. burgdorferi-infected mice. The p30 gene is 801 nucleotides in length and P30 contains 267 amino acids, with a predicted molecular mass of 30 kDa. The P30 amino acid region 36-258 has homology to conserved domains of the oligopeptide permease A of Gram-negative bacteria. Immunofluorescence studies using murine anti-P30 serum suggest that P30 is on the outer surface of B. burgdorferi. P30 expression could be detected in representatives of all 3 subspecies of B. burgdorferi sensu lato, but not in all of the tested strains. Antibodies to P30 were detected in sera of 18 out of 82 patients (22%) with Lyme disease, including individuals with early- or late-stage infection. Although antibodies to P30 are present in the sera of C3H/HeN mice infected with B. burgdorferi for at least 90 days, immunization with recombinant P30 does not protect mice from infection. We conclude that P30 is a putative substrate-binding protein of B. burgdorferi and is immunologically recognized in human and murine Lyme borreliosis.

Animals↗
PubMedDate not supplied

Transcatheter embolization of biopsy-related vascular injury in the transplant kidney: immediate and long-term outcome.

PURPOSE: To assess the effect of transcatheter embolization for treatment of biopsy-related vascular injury in renal allografts, specifically evaluating technical success, clinical benefit, and long-term effect on renal function. MATERIALS AND METHODS: A retrospective review was performed of all postbiopsy renal allograft vascular injuries referred for embolization during a 113-month period. The likelihood of a prolonged detrimental effect on allograft function was estimated from observed variation in serum creatinine levels before and after the procedure. RESULTS: Embolic therapy with use of metallic coils and superselective technique was performed in 21 renal transplant patients. Technical success was achieved in 95% of cases. There were no serious complications. Eradication of the clinical sign or symptom prompting referral was seen in 15 of 17 (88%) patients. Eleven of 19 (58%) patients analyzed demonstrated no evidence of a long-term detrimental effect on allograft function. A detrimental effect was possibly present in six of 19 (32%) patients, and probable in only two of 19 (10%) patients. CONCLUSIONS: Transcatheter embolization can be an appropriate and effective therapeutic choice for biopsy-related renal allograft vascular injury.

Adolescent↗
PubMedDate not supplied

Evaluation of urinary 1-hydroxypyrene, S-phenylmercapturic acid, trans,trans-muconic acid, 3-methyladenine, 3-ethyladenine, 8-hydroxy-2'-deoxyguanosine and thioethers as biomarkers of exposure to cigarette smoke.

The objective was to evaluate the utility of urinary 1-hydroxypyrene (1-OHP), S-phenylmercapturic acid (S-PMA), trans,trans-muconic acid (t,t-MA), 3-methyladenine (3-MeAd), 3-ethyladenine (3-EtAd), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and thioethers as biomarkers for assessing the exposure in adult smokers who switched from smoking conventional cigarettes to candidate potential reduced exposure products (PREP) or who stopped smoking. Two electrically heated smoking systems (EHCSS) were used as prototype cigarettes that have significant reductions in a number of mainstream smoke constituents as measured by smoking machines relative to those from conventional cigarettes. Urine samples were collected from a randomized, controlled, forced-switching study in which 110 adult smokers of a conventional cigarette brand (CC1) were randomly assigned to five study groups. The groups included the CC1 smoking group, a lower-tar conventional cigarette (CC2) smoking group, EHCSS1 group, EHCSS2 group and a no smoking group that were monitored for 8 days. Biomarkers were measured at baseline and day 8. The daily excretion levels of these biomarkers were compared among the groups before and after switching, and the relationships between the daily excretion levels of these biomarkers and cigarette smoking-related exposure were investigated using Pearson product-moment correlation and multiple regression analyses. It was concluded that under controlled study conditions: (1) 1-OHP, S-PMA and t,t-MA are useful biomarkers that could differentiate exposure between smoking conventional and EHCSS cigarettes or between smoking conventional cigarettes and no smoking; between S-PMA and t,t-MA, the former appeared to be more sensitive; (2) 3-MeAd could only differentiate between smoking conventional cigarettes and no smoking; the results for 3-EtAd were not conclusive because contradictory results were observed; (3) 8-OHdG had a questionable association with smoking and therefore the utility of this biomarker for smoking-related exposure could not be established; and (4) urinary excretion of thioethers as a biomarker lacked sensitivity to demonstrate a clear dose-response relationship in conventional cigarette smokers, although it could differentiate the excretion levels between those subjects who smoked a conventional cigarette and those who stopped smoking.

8-Hydroxy-2'-Deoxyguanosine↗
PubMedDate not supplied

delta 9-THC metabolites in meconium: identification of 11-OH-delta 9-THC, 8 beta,11-diOH-delta 9-THC, and 11-nor-delta 9-THC-9-COOH as major metabolites of delta 9-THC.

Gas chromatography-mass spectrometry (GC-MS) analysis of meconium specimens screening positive for cannabinoids by the EMIT 20 Assay showed a low confirmation rate for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). A study was designed to investigate the possible contribution of other delta 9-tetrahydrocannabinol (THC) metabolites, including glucuronides, to the overall response of the EIA. delta 9-THC-glucuronide was synthesized in order to develop the most efficient procedure for hydrolysis of glucuronides in meconium. Procedures were developed for the extraction and GC-MS analysis of delta 9-THC, 11-OH-delta 9-THC, 8 alpha- and 8 beta-OH-delta 9-THC, 8 beta,11-diOH-delta 9-THC, and THCCOOH, after enzymatic hydrolysis of meconium extracts. It is concluded that enzymatic hydrolysis of meconium extracts is necessary for efficient recovery of delta 9-THC metabolites; delta 9-THC and its 8-OH metabolite(s) are basically absent in meconium specimens; and 11-OH-delta 9-THC and 8 beta,11-diOH-delta 9-THC contribute significantly to the immunoassay response of meconium extracts. Analysis of several meconium specimens that screened positive for cannabinoids but failed to confirm for THCCOOH showed significant amounts of 11-OH-delta 9-THC and 8 beta,11-diOH-delta 9-THC. Therefore, GC-MS confirmation of cannabinoids in meconium should include analysis for these two metabolites in addition to THCCOOH.

Dronabinol↗
PubMedDate not supplied

Analysis of methadone and its metabolites in meconium by enzyme immunoassay (EMIT) and GC-MS.

An EMIT-ETS d.a.u. immunoassay screening method for methadone in meconium and a gas chromatography-mass spectrometry (GC-MS) method for methadone and its metabolites including 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenylpyrroline (EMDP) in meconium were described. The GC-MS method showed good linearity (r2 > or = 0.998) over a concentration range of 25-2000 ng/g with limits of detection of 10, 25, and 10 ng/g for methadone, EDDP, and EMDP, respectively, and a limit of quantitation of 25 ng/g for all three analytes. Fifty pooled meconium samples were screened using a cutoff of 200 ng/g, and all samples screened negative. GC-MS analysis of all samples showed four samples to contain methadone (35.2 to 79.9 ng/g), EDDP (28.5 to 557.2 ng/g), or both, with no detectable amount of EMDP. The negative results on the four specimens at the cutoff used may be explained by the fact that EMIT-ETS d.a.u. antibody for methadone was specific to the parent drug. The results point to the fact that immunoassays should be directed to EDDP for detection of prenatal exposure of methadone through analysis of meconium specimens.

Enzyme Multiplied Immunoassay Technique↗
PubMedDate not supplied

Serum and urine concentrations of flunitrazepam and metabolites, after a single oral dose, by immunoassay and GC-MS.

A clinical study was conducted to assess the ability of commercially available immunoassays to detect flunitrazepam (FNP) in plasma and urine samples and to compare the results with those obtained by gas chromatography-mass spectrometry (GC-MS). The clinical study consisted of four individuals (two male and two female) who had taken a single 2-mg dose of FNP. Serum was collected over a 48-h period and urine was collected over a 72-h period. The serum and urine samples were analyzed by the COBAS INTEGRA Serum Benzodiazepines assay (SBENZ), the TDx serum and urine Benzodiazepines assay, and GC-MS. The GC-MS procedure was developed for analysis of FNP and metabolites in plasma and urine using an acid hydrolysis step resulting in the formation of specific benzophenones corresponding to FNP and its metabolites. The relative sensitivities of the assays for the detection of FNP and metabolites in serum and urine were GC-MS > SBENZ > TDx. The immunoassay results for serum samples showed peak concentrations of FNP metabolites at 8 h after FNP ingestion for three individuals and at about 1 h for the fourth individual. The GC-MS, SBENZ, and TDx urine immunoassays detected drug above the stated limit of detection (LOD) in 44, 41, and 35 serial FNP urine samples, respectively. FNP metabolites were detected in urine samples with all three assays for up to 72 h after a 2-mg dose. The improved detection rate with the SBENZ assay as compared to the TDx assay is likely explained by its higher cross-reactivity with the major metabolite, 7-amino-flunitrazepam (7-amino-FNP), and its lower LOD.

Administration, Oral↗
PubMedDate not supplied

Parathyroid reoperation with use of technetium 99m sestamibi radiolocalization and an intraoperative gamma counter.

OBJECTIVE: To describe a new intraoperative technique for localization of abnormal parathyroid tissue. METHODS: We report a case and discuss the difficulties encountered in reexploration of the neck area. RESULTS: Parathyroid reoperation remains a formidable challenge to even the most experienced endocrine surgeon. Despite the advances in radiographic imaging and localization techniques, accurate intraoperative identification of abnormal parathyroid tissue in a scarred field with obliterated anatomic planes is frequently tedious and occasionally unsuccessful. In a 48-year-old woman with hyperparathyroidism, extensive exploration of the area identified (on the basis of preoperative magnetic resonance imaging and technetium 99m sestamibi scans) as suspicious for the presence of abnormal parathyroid tissue revealed only an aberrant vein. With use of a handheld gamma counter to provide intraoperative guidance during parathyroid reexploration after preoperative intravenous injection of technetium 99m sestamibi, quick identification of a small, intrathyroidal, fifth gland adenoma responsible for persistent primary hyperparathyroidism was facilitated. CONCLUSION: Because of suboptimal precision and specificity, current preoperative localization studies can occasionally provide misleading information. Particularly in difficult cases of parathyroid reexploration, an instrument capable of localizing abnormal parathyroid tissue, which can be used intraoperatively with ease, can be an invaluable tool to ensure a safe, expedient, and successful surgical outcome.

Journal Article↗