Search PubMed⌕ Search

Biomedical subjects

J C Yang

Publications and source records attributed to J C Yang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Prevalence and rapid identification of clarithromycin-resistant Helicobacter pylori isolates in children.

BACKGROUND: Little is known about the prevalence of antibiotic-resistant Helicobacter pylori infection in children. Culture and antimicrobial susceptibility testing are generally time-consuming and not a routine in many hospitals. OBJECTIVE: To investigate the prevalence of clarithromycin-resistant H. pylori strains in children, to identify those isolates via rapid methodology and to examine the severity of gastritis caused by the antibiotic-resistant H. pylori isolates. METHODS: Enrolled were 245 children investigated for H. pylori infection by endoscopic examination. The gastric antral specimens were subjected to DNA extraction and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with primers specific to the H. pylori 23S rRNA gene. Conventional bacterial cultures were performed simultaneously as the diagnostic standard. Minimal inhibitory concentrations of clarithromycin and metronidazole were determined by E test. This was used as a standard to determine the sensitivity and specificity of the above PCR-RFLP assay. The specimens were processed for histologic examination and evaluated by the updated Sydney system. RESULTS: H. pylori was isolated in 67 of the 245 children; 12 (18%) of them were clarithromycin-resistant and 6 (9%) were metronidazole-resistant. No difference in histologic examinations was noted between the antibiotic-resistant and -susceptible strains. We performed PCR-RFLP with all 12 clarithromycin-resistant isolates: 10 had a 23S ribosomal RNA A2144G point mutation; 1 had a mixture of an A2143G point mutant and susceptible strains; and 1 had neither of the 2 mutations. CONCLUSIONS: The prevalence of clarithromycin-resistant H. pylori isolates in Taiwanese children is 18%. PCR-RFLP had a high sensitivity (92%) and specificity (100%) for the clarithromycin resistance gene mutation determination. The dominant mutation is A2144G. PCR-RFLP provides a rapid and accurate approach to detect clarithromycin-resistant strains within 24 h.

Adolescent↗
PubMed2001

HMG-D complexed to a bulge DNA: an NMR model.

An NMR model is presented for the structure of HMG-D, one of the Drosophila counterparts of mammalian HMG1/2 proteins, bound to a particular distorted DNA structure, a dA(2) DNA bulge. The complex is in fast to intermediate exchange on the NMR chemical shift time scale and suffers substantial linebroadening for the majority of interfacial resonances. This essentially precludes determination of a high-resolution structure for the interface based on NMR data alone. However, by introducing a small number of additional constraints based on chemical shift and linewidth footprinting combined with analogies to known structures, an ensemble of model structures was generated using a computational strategy equivalent to that for a conventional NMR structure determination. We find that the base pair adjacent to the dA(2) bulge is not formed and that the protein recognizes this feature in forming the complex; intermolecular NOE enhancements are observed from the sidechain of Thr 33 to all four nucleotides of the DNA sequence step adjacent to the bulge. Our results form the first experimental demonstration that when binding to deformed DNA, non-sequence-specific HMG proteins recognize the junction between duplex and nonduplex DNA. Similarities and differences of the present structural model relative to other HMG-DNA complex structures are discussed.

Animals↗
PubMed2001

Medication lists for elderly patients: clinic-derived versus in-home inspection and interview.

OBJECTIVE: To determine how often the lists of regular medications derived in geriatric clinics by examination of "medication bags" and interview matched those found during in-home inspections and interviews. DESIGN: Prospective cross-sectional study. SETTING: Geriatric clinics at three university-affiliated hospitals. PARTICIPANTS: Consecutive community-dwelling outpatients 65 years or older who were newly referred. METHODS: The in-home medication inspection used a semistructured interview followed by a room-to-room search. The medications identified in the home were compared with the medication list derived in clinic by examination of the "medication bag" and interview. MAIN RESULTS: Fifty patients with a mean age of 78.9 years participated. The mean number of regular medications (prescription and nonprescription) was 6.3, and the mean number of regular prescription medications was 3.6. A comparison of clinic versus in-home medication lists revealed that 48% (95% confidence interval [95% CI], 34% to 62%) of patients had at least 1 omission of any regular medication and 19% (95%, CI 10% to 32%) of patients had at least 1 omission of a regular prescription medication. CONCLUSION: The clinic-derived medication list resulted in a complete listing of all regular medications in only 52% taking regular medications. More specific instructions to patients to bring all prescription and nonprescription medications and all vitamins, herbal, and natural remedies, and more directed questions by physicians may result in more complete clinic medication lists.

Aged↗
PubMed2001

Effect of American ginseng extract (Panax quinquefolius) on formalin-induced nociception in mice.

Twenty-three ICR mice were force fed orally with American ginseng extract, Panax quinquefolius, (Cold FX) for 4 days. Another 20 mice were fed with water as placebo in a similar fashion. Formalin tests which yield typically two phases of pain behavior were done in both groups. Although there was no difference in the first phase between groups, mice treated with Cold FX spent significantly less time in licking and biting of the injured paws in the second phase. The data indicate that American ginseng may have analgesic effect in this chronic pain model.

Analgesics↗
PubMed2001

A preliminary report on the Chinese Cancer Pain Assessment Tool (CCPAT): reliability and validity.

BACKGROUND: This study was to establish the validity and reliability of the Chinese Cancer Pain Assessment Tool (CCPAT) for Chinese patients with cancer pain in Hong Kong. METHODS: It was a quasi-experimental study. The CCPAT was tested for its reliability and validity by 26 cancer pain patients and 26 chronic non-cancer pain patients. McGill Pain Questionnaire (MPQ), with its established reliability and validity, was used as the criterion tool for comparison. RESULTS: An internal consistency of 0.88 and the inter-rater reliability of 0.96 were obtained for the CCPAT. The Spearman's Rho correlations between the functional and emotional dimensions of the CCPAT and the present pain intensity of the MPQ positively correlated. This indicated a satisfactory concurrent validity. Discriminant validity was performed with MANOVA. The CCPAT was able to predict 80.8% of the subjects correctly as cancer pain patient from the cancer pain group. CONCLUSIONS: The constructed CCPAT is a valid and reliable cancer pain assessment tool in a Chinese context. The developed CCPAT is the first of its kind for the Chinese community in Hong Kong. It is anticipated that the results can provide the health care professionals with the best possible instrument and indicator. The CCPAT also lays the theoretical construct for the professionals with a better understanding of the experience of cancer pain from a multidimensional perspective.

Adult↗
PubMed2001

Lack of retroperitoneal lymphadenopathy predicts survival of patients with metastatic renal cell carcinoma.

PURPOSE: Patients with metastatic renal cell carcinoma have a reported 5-year survival of 0% to 20%. The ability to predict which patients would benefit from nephrectomy and interleukin-2 (IL-2) therapy before any treatment is initiated would be useful for maximizing the advantage of therapy and improving the quality of life. MATERIALS AND METHODS: A retrospective analysis of the x-rays and charts of patients treated at the National Institutes of Health Surgery Branch between 1985 and 1996, who presented with metastatic renal cancer beyond the locoregional area and the primary tumor in place, was performed. Preoperative computerized tomography or magnetic resonance imaging, or radiological reports if no scans were available, were used to obtain an estimate of the volume of retroperitoneal lymphadenopathy. Operative notes were used to evaluate whether all lymphadenopathy was resected or disease left in situ, or if any extrarenal resection, including venacavotomy, was performed. Mean survival rate was calculated from the time of nephrectomy to the time of death or last clinical followup. If patients received IL-2 therapy, the response to treatment was recorded. Mean survival and response rate for IL-2 were compared among patients in 3 separate analyses. Patients without preoperatively detected lymphadenopathy were compared with those with at least 1 cm.3 retroperitoneal lymphadenopathy. Also, the patients who had detectable lymphadenopathy were divided into subgroups consisting of all resected, incompletely resected, unresectable and unknown if all disease was resected. Each subgroup was compared with patients without detectable preoperative lymphadenopathy. Patients with less than were compared to those with greater than 50 cm.3 retroperitoneal lymphadenopathy. Patients undergoing extrarenal resection at nephrectomy (complex surgery) due to direct invasion of the tumor into another intra-abdominal organ were compared with those undergoing radical nephrectomy alone, regardless of lymph node status. Statistical analysis was done with the Mantel-Cox test for comparison of survival on Kaplan-Meier curves and with Fisher's exact test for response rates for IL-2. RESULTS: A total of 154 patients with metastatic renal cell carcinoma underwent cytoreductive nephrectomy as preparation for IL-2 based regimens. There were 82 patients with metastatic renal cell carcinoma and no preoperative retroperitoneal lymphadenopathy who survived longer (median 14.7 months) than the 72 with lymphadenopathy (median 8.5, p = 0.0004). Patients with incompletely resected, unresectable or an unknown volume resected had decreased survival compared to those with no retroperitoneal lymphadenopathy. A multivariate analysis of survival was performed evaluating the known prognostic indicators, performance status and tumor burden, as represented by the number of organs involved with metastases, and the new prognostic factor, lymphadenopathy. Lymphadenopathy was more closely associated with survival than performance status, and appeared to be a new prognostic variable. Patients with and without retroperitoneal lymphadenopathy at initial presentation had similar rates for treatment with IL-2 (54% for both groups). Of the 82 patients with no lymphadenopathy 11 (13%) had long-term survival greater than 5 years. Of the 6 complete responses to IL-2, 5 occurred in this group. Only 1 other patient with incompletely resected retroperitoneal lymphadenopathy survived longer than 5 years. No significant difference in survival was seen between patients who did or did not undergo complex surgery. CONCLUSIONS: Patients who presented with metastatic renal cancer and retroperitoneal lymphadenopathy had a shorter survival than those with no detectable retroperitoneal lymphadenopathy. It is warranted to continue to perform complex extrarenal resection during nephrectomy since no significant difference in the response rate for IL-2 or mean survival compared with those of patients undergoing nephrectomy alone is currently detectable.

Adult↗
PubMed2000

The structural basis for the recognition of acetylated histone H4 by the bromodomain of histone acetyltransferase gcn5p.

The bromodomain is an approximately 110 amino acid module found in histone acetyltransferases and the ATPase component of certain nucleosome remodelling complexes. We report the crystal structure at 1.9 A resolution of the Saccharomyces cerevisiae Gcn5p bromodomain complexed with a peptide corresponding to residues 15-29 of histone H4 acetylated at the zeta-N of lysine 16. We show that this bromodomain preferentially binds to peptides containing an N:-acetyl lysine residue. Only residues 16-19 of the acetylated peptide interact with the bromodomain. The primary interaction is the N:-acetyl lysine binding in a cleft with the specificity provided by the interaction of the amide nitrogen of a conserved asparagine with the oxygen of the acetyl carbonyl group. A network of water-mediated H-bonds with protein main chain carbonyl groups at the base of the cleft contributes to the binding. Additional side chain binding occurs on a shallow depression that is hydrophobic at one end and can accommodate charge interactions at the other. These findings suggest that the Gcn5p bromodomain may discriminate between different acetylated lysine residues depending on the context in which they are displayed.

Acetylation↗
PubMed2000

Bcl-2 does not inhibit the permeability transition pore in mouse liver mitochondria.

The mechanism by which the mitochondrially-localized Bcl-2 protein inhibits apoptosis is still unclear. Some authors have proposed that apoptosis is dependent on induction of the mitochondrial permeability transition pore (PTP), and that activators of apoptosis such as Bax work through activation of PTP, whereas inhibitors of apoptosis such as Bcl-2 work through inhibition of PTP, and the consequent activation or inhibition of PTP-dependent release of mitochondrial apoptotic factors, including cytochrome c. PTP opening is classically measured by a light-scattering assay of large-amplitude swelling of rodent liver mitochondria in sucrose media. Thus to test the hypothesis that Bcl-2 inhibits either the PTP or the PTP-dependent release of cytochrome c, the rate and extent of PTP, and PTP-dependent release of cytochrome c were compared in liver mitochondria from control and Bcl-2 transgenic mice. We demonstrated that Bcl-2 protein was expressed to high levels in mitochondria of transgenics versus controls. We confirmed that while control mice undergo massive hepatic cell death upon exposure to anti-Fas antibody, the Bcl-2 transgenic livers were resistant, by the criteria of gross morphology, serum enzyme release, and caspase 3 activity. We purified mitochondria from livers of the Bcl-2 transgenics and measured PTP directly by the mitochondrial swelling assay. Purified mitochondria from both transgenics and controls were induced to undergo large-amplitude swelling that was dependent on the classical PTP inducers calcium ion (Ca(2+)), t-butyl hydroperoxide (tBOOH) and atractyloside (Atr); and as expected, pretreatment of mitochondria with cyclosporin A (CsA) completely abolished mitochondrial swelling. However, there was no difference in the rate or final extent of PTP induction in Bcl-2 overexpressors versus control mitochondria. Furthermore, there was no difference in the PTP dependent release of cytochrome c from Bcl-2 overexpressors versus control mitochondria. Therefore, while we observe a strong inhibition of Fas-dependent apoptosis by Bcl-2 overexpression in mouse liver, we observe no effect of Bcl-2 overexpression on either the rate or extent of mitochondrial PTP, or upon the release of cytochrome c from mitochondria in which the PTP has been induced. The simplest explanation of these results is that Bcl-2 inhibits neither PTP nor PTP-dependent release of cytochrome c, however, other possibilities are discussed.

Animals↗
PubMed2000

Morphine and methadone have different effects on calcium channel currents in neuroblastoma cells.

Using patch-clamp technique, cellular calcium channel currents were studied on nine mouse neuroblastoma N1E115 cells. Both morphine and methadone decreased the T-type calcium currents in dose-dependent fashion. These effects were partially blocked by naloxane. On L-type calcium currents, morphine showed no effect. However, methadone inhibited the L-calcium currents in dose-dependent fashion. This effect was not antagonised by naloxone. Hence, the action of methadone on L-calcium channel is probably not associated with mu receptors.

Animals↗
PubMed2000

A morphometric evaluation of allograft matrix combinations in the treatment of osseous defects in a baboon model.

Recent and ongoing research efforts have been made to increase the efficacy of biomaterials as structural fillers during in vivo bony reconstructions. Although the selection of the possible material choices has grown, a biomaterial that can be physically molded to the defect/void space as well as offer biomimetic tissue regeneration has yet to be made available. With the potential success of demineralized freeze-dried bone allografts (DFDBA) combined with tendonous collagen as an effective filling material, further research should help to elucidate its use. The purpose of this study was to evaluate the regenerative healing response of five allograft mixtures via the morphology of filled, periodontal defects. Critical size mandibular and maxillary osseous defects were surgically created in six adult baboons. The filling response of four combinations of DFDBA and tendon collagen was compared with an all-collagen graft after 3 months of implantation. The overall results indicate that all combinations of DFDBA and collagen provided a better fill response than the all-collagen matrix (P < 0. 05). Statistically, however, all of the combinations were similar (P > 0.05) with a 60:40 collagen to DFDBA mass ratio resulting in the largest defect fill response.

Alveolar Ridge Augmentation↗
PubMed2000

Rapid and Semi-automated Method for Analysis of the Number of Atoms of Ultra-small Platinum Clusters on Carbon.

Very high angle ( approximately 100 mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the number of atoms in a cluster on a support material. We have developed a computer program which will automatically find the location of the particles and then integrate the intensity to find the number of atoms per cluster. We have examined ultra-small Pt clusters on a C substrate by this novel mass-spectroscopic technique. We discovered that the Pt clusters maintain their three-dimensional shape, and are probably spherical.

Journal Article↗
PubMed2000

Tumorigenicity and immunogenicity of murine tumor cells expressing an MHC class II molecule with a covalently bound antigenic peptide.

The significance of CD4+ lymphocytes and major histocompatibility complex (MHC) class II-restricted antigens in antitumor immunity has been demonstrated in several animal models as well as in some human tumors. However, because of the lack of known class II-restricted antigens, the participation of CD4+ cells in antitumor responses has not been well characterized. Recent reports showed that class II proteins covalently linked to an antigenic peptide could be constructed and cells expressing these fusion proteins were recognized by specific TH cells. The aim of this study was to determine the effect of the expression of a class II-peptide construct on the tumorigenicity and immunogenicity of transfected murine tumor cells. We have constructed a gene for I-Ed beta chain covalently coupled to the I-Ed-restricted TH cell determinant of sperm whale myoglobin (SWM132-145). This class II fusion protein was recognized by a specific TH cell line on the surface of COS-7 cells or BALB/c sarcoma cells. The sarcoma cells expressing the MHC-peptide complex were rejected by immunocompetent BALB/c mice, and in vivo T-cell subset depletion experiments suggested the importance of CD4+ cells in the rejection. Moreover, splenocytes from mice immunized with tumor cells expressing the I-Ed-SWM complex showed specific peptide recognition in vitro. Such covalent MHC-peptide complexes could prove useful in studies on the role of CD4+ lymphocytes in antitumor immune responses, and also in designing new, more effective vaccine approaches to the immunotherapy of cancer, as class II-restricted tumor-associated antigens are identified for human cancers.

Amino Acid Sequence↗
PubMed2000

Preoperative Multidimensional Affect and Pain Survey (MAPS) scores predict postcolectomy analgesia requirement.

OBJECTIVES: One aim of this study was to evaluate the relation of scores on the Multidimensional Affect and Pain Survey (MAPS) that was administered before surgery to postoperative morphine consumption and patient-controlled analgesia. A second aim of the study was to compare the ability of MAPS administered postsurgery with the commonly used Numerical Pain Rating Scale to predict patient-controlled analgesia behavior. DESIGN: The MAPS questionnaire measures pain, suffering, and well-being. It was administered to patients 1 day before and 1 day after left hemicolectomy for colon cancer. The relations of the two scores to postoperative pain control were determined. PATIENTS: Thirty-four patients in the surgical ward of a general hospital admitted for colorectal cancer surgery participated in this study. RESULTS: High preoperative MAPS scores on sensory and emotional words predicted postoperative morphine dosage, dose presses, and lockout presses. Greater morphine consumption was correlated positively with high presurgery MAPS scores in four of the eight "Suffering" subclusters (Depressed Mood, Anger, Anxiety, and Fear). High presurgery MAPS scores in 13 of the 17 "Sensory Qualities" subclusters (e.g., Bothersome, Intense Pain, Pain Extent, Incisive Pressure, Traction/Abrasion) were correlated positively with lockout presses. Neither the postsurgery MAPS nor the postsurgery Numerical Pain Rating Scale predicted patient-controlled analgesia behavior. CONCLUSION: The emotional states and attitudes of the patients toward pain before surgery are important factors in determining patient-controlled analgesia pressing behavior and postoperative demand for analgesics.

Adult↗
PubMed2000

The lens model: assessment of cancer pain in a Chinese context.

Obtaining a result closest to patients' reports about pain is crucial in pain management. The literature in the West supports the view that there are cultural differences in perception, interpretation, and expression of pain. However, there has been minimal review in Chinese communities. Therefore, the concepts of cancer pain among Chinese patients with cancer were explored by data source triangulation. There were 33 informants: 18 adult Chinese patients with cancer who were in pain, 7 physicians, and 8 nurses. The interview dialogue was transcribed into written Chinese, followed by coding and categorization. There were no predetermined themes for categorization. The dialogue was coded according to the contextual meaning. The nature and number of categories depended entirely on the coding. Five dimensions were identified: functional, pharmacologic, pain belief and meanings, psychosocial, and emotional. With reference to the five dimensions, a lens model was constructed to explain the cancer pain experience in a Chinese context. In the lens model, two lenses were used to illustrate the relations of the dimensions and cancer pain experience in the Chinese context. The pain experience was named as total pain intensity. The functional, pharmacologic, psychosocial, and emotional dimensions were the independent variables. The pain beliefs and meanings dimension was the mediating variable, and the dependent variable was the total pain intensity in the assessment of cancer pain.

Adult↗
PubMed2000

Chemical modification of a variant of human MIP-1alpha; implications for dimer structure.

A sequence variant of human MIP-1alpha, in which Asp26 has been replaced by Al alpha, has been chemically modified by the addition of 13C-labeled methyl groups at each of the lysine residues and the N-terminus. The sites of methylation have been verified by a combination of MALDI-TOF mass spectrometric experiments and tryptic digestion followed by N-terminal mapping. The effect of the modification on the structure and activity of the protein have been determined by analytical ultra-centrifugation, 13C NMR spectroscopy and receptor binding studies. The results of these experiments suggest that huMIP-alpha D26A (BB10010), when present as a dimer, adopts a globular structure, like MCP-3, rather than the elongated or cylindrical structure determined for dimers of huMIP-1beta and RANTES.

Alanine↗
PubMed2000

Accurate diagnosis of Helicobacter pylori infection by stool antigen test and 6 other currently available tests in children.

Invasive and noninvasive tests have been developed for the diagnosis of Helicobacter pylori infection. Because H pylori infection is acquired in childhood and adolescence, accurate diagnosis of the infection in the pediatric population is important. We conducted a study to compare invasive tests: culture, biopsy urease test, histology, and polymerase chain reaction on gastric biopsy specimens, with noninvasive tests: serology, (13)C-urea breath test, and a new diagnostic modality, stool antigen test to diagnose H pylori infection. A total of 53 children with symptoms were enrolled in this study, and all had completed the 7 diagnostic tests for H pylori. All the diagnostic tests except serology were excellent methods of diagnosing H pylori infection in children; the diagnostic accuracy was as follows: stool antigen test 96.2%, biopsy urease test 96.2%, histology 98.1%, polymerase chain reaction 94.3%, culture 98.1%, (13)C-urea breath test 100%, and serology 84.9%. The stool antigen test, being highly sensitive and specific, will be potentially very helpful in diagnosing H pylori infection in children.

Adolescent↗
PubMed2000

Combined effect of isoflurane and esmolol on sympathetic responses to tracheal intubation.

BACKGROUND: Influences of isoflurane and esmolol on endotracheal intubation induced sympathetic changes could be different. The effect of isoflurane and its combination with esmolol on catecholamine, blood pressure and pulse during endotracheal intubation were investigated. METHODS: Thirty patients were anesthetized with 3.0% isoflurane and tracheal intubation was carried out at the 5th min following the exposure to isoflurane. Half of them received intravenous saline and the other half received esmolol 2 mg/kg at the 4th min. Cardiovascular parameters were recorded and venous blood samples were taken for measurement of catecholamines every min. RESULTS: One min after administration of isoflurane, there was increase of heart rate (P < 0.05), while at the same time the epinephrine level fell (P < 0.05) and norepinephrine level remained unaltered. Both catecholamines raised after intubation (P < 0.05). The sympathetic responses to and the beta-antagonistic effect of esmolol on intubation were not significantly changed in the presence of isoflurane. CONCLUSIONS: Isoflurane increased heart rate while paradoxically decreased epinephrine. Norepinephrine was more specifically related to endotracheal intubation, for its serum level had little change before the event. Based on catecholamine findings, the mechanism of isoflurane effect on the sympathetic system is probably different from that of endotracheal intubation.

Adrenergic beta-Antagonists↗