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Biomedical subjects

L C Chang

Publications and source records attributed to L C Chang.

At least 55 records · Page 3Linked to original sources
PubMed1996

Seven- to 10-year outcome of decompressive surgery for degenerative lumbar spinal stenosis.

STUDY DESIGN: Retrospective review and prospective follow-up of 88 patients who had decompressive laminectomy with or without fusion from 1983 to 1986. OBJECTIVE: To determine the 7- to 10-year outcome of surgery for degenerative lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: There is limited information on the impact of surgery for lumbar spinal stenosis on symptoms, walking ability, and satisfaction, as well as reoperation. METHODS: Patients completed standardized questionnaires in 1993 that included items about reoperations, back pain, leg pain, walking capacity, and satisfaction with surgery. Associations between preoperative demographic and clinical variables and outcomes 7 to 10 years after surgery were evaluated in univariate and multivariate analyses. RESULTS: Average preoperative age was 69 years and eight patients received fusion. Of 88 patients in the original cohort, 20 (23%) were deceased and 20 (23%) had undergone reoperation by 7- to 10-year follow-up. Fifty-five patients answered questionnaires. Average duration of follow-up was 8.1 years. Thirty-three percent of the respondents had severe back pain at follow-up, 53% were unable to walk two blocks, and 75% were satisfied with the results of surgery. The severity of current spine-related symptoms was a stronger correlate of physical functional status at the time of follow-up than age or nonspinal comorbid conditions. CONCLUSIONS: Seven to 10 years after decompressive surgery for spinal stenosis, 23% of patients had undergone reoperation and 33% of respondents had severe back pain. Despite a high prevalence of nonspinal problems in this elderly cohort, spinal symptoms were the most important correlate of reduced functional status.

Aged↗
PubMed1996

A micro liquid chromatographic assay for the determination of plasma-unbound atenolol.

An improved high performance liquid chromatographic assay for plasma-unbound atenolol is described. The assay has a wide range (10-5000 ng ml-1) of linearity and a detection limit of 5 ng ml-1 (or 0.1 ng per injection) with acceptable intra- and inter-assay reproducibilities using small volumes of plasma (100 microliters). Following administration of a single dose of atenolol to the rat, nine blood samples were collected over a period of 8 h. These samples were analyzed for atenolol concentrations by a sensitive and specific microbore high performance liquid chromatograph with a photodiode-array detector. This multi-channel detector was used to acquire spectral information on atenolol and demonstrated a superior performance in comparison to all other techniques in that both qualitative and quantitative information were acquired with the system. Because of it sensitivity and applicability to plasma analysis, the assay can be used for pharmacokinetic studies and is valuable in therapeutic drug monitoring.

Animals↗
PubMed1996

Can comorbidity be measured by questionnaire rather than medical record review?

Comorbidity generally is measured by medical record abstraction, which is expensive and often impractical. The aim of this study was to assess the reproducibility and validity of a comorbidity questionnaire. The authors developed a brief comorbidity questionnaire that included items corresponding to each element of the medical record-based Charlson index. The questionnaire was administered to 170 inpatients. Charlson scores were abstracted from these patients' medical records. We assessed test-retest reliability of the questionnaire and the Charlson index, the correlation between the questionnaire and the Charlson index, and correlations between each comorbidity measure and indicators of health resource utilization including medication use, hospitalizations in the past year, and hospital charges. Test-retest reliability, assessed with the intraclass correlation coefficient, was 0.91 for the questionnaire and 0.92 for the chart-based Charlson index. The Spearman correlation between these two measures was 0.63. The correlation between comorbidity measures was weaker in less educated patients. Correlations with indicators of resource utilization were similar for the two comorbidity instruments. The authors found that a questionnaire version of the Charlson index is reproducible, valid, and offers practical advantages over medical record-based assessments.

Aged↗
PubMed1996

Prenatal diagnosis of osteogenesis imperfecta congenita by ultrasonography.

As well as being a rare connective tissue disorder, osteogenesis imperfecta congenita (OIC) is also the most severe form of osteogenesis imperfecta (OI). We report a case that was diagnosed by sonography in a fetus at 22 weeks of gestation. The diagnosis was confirmed by postnatal radiography and autopsy. The prenatal sonographic findings were: short bowed femurs with fractures and thin skull with unusual clarity of intracranial structures. The postnatal radiography showed crumbled long bones and beaded ribs compatible with multiple fractures, similar to the prenatal sonographic findings. The major findings on autopsy were deformed skull and ribs and asymmetric deformity of the four extremities. The microscopic findings of the skeleton, including skull, vertebrae, ribs and long bones, revealed normal cartilagenous development but abnormal bone formation. The pathologic features of the skeleton were compatible with osteogenesis imperfecta type II, ie, OIC. Fractures and bone deformities are the cardinal symptoms of OIC which make intrauterine diagnosis possible. It should be differentiated from other types of OI (I, III and IV), as their prognoses are different. As OIC is lethal, the option of pregnancy termination should be offered at the time it is diagnosed. In the present report, termination by extraovular induction was performed immediately after OIC was noted on sonography.

Abortion, Induced↗
PubMed1996

Antituberculosis drug resistance in Keelung area-1993 to 1994.

Patterns of drug resistance of 176 isolates of Mycobacterium tuberculosis collected from 1993 to 1994 were reviewed retrospectively. The rates of resistance to isoniazid, rifampicin, ethambutol and streptomycin were 84.1%, 17.6%, 23.3% and 11.9% respectively and the incidence of multidrug-resistant M. tuberculosis was 17.0%. Comparisons between 1993 and 1994 showed decrease in rates of resistance to rifampicin (25% vs. 7.5%) and ethambutol (36.5% vs. 7.5%) and the incidence of multidrug-resistant tuberculosis (25% vs. 7.5%). In contrast, the rate of resistance to isoniazid increased from 79.2% to 84.1%. Due to the high frequency of resistance to multiple drugs in tuberculosis isolates at Chang Gung Memorial Hospital, Keelung, three-combined (isoniazid+rifampicin+ethambutol) regimen of antituberculosis drugs may be ineffective as initial therapy for one-fourth of patients in our hospital. Of epidemiological factors, previous treatment was found to influence the rates of drug resistance. Of roentgenographic features, stage of chest roentgenography was found to be a positive predictor of infection with multidrug-resistant tuberculosis. The information provided in this study may help us understanding the epidemiology of M. tuberculosis in Keelung and refining antituberculosis treatment for our patients.

Adult↗
PubMed1996

[In vivo study of potassium oxalate gel in tooth hypersensitivity].

This study was aimed to test the effectiveness of a new desensitizing agent-30% potassium oxalate gel in tooth hypersensitivity. Thirty adult patients with 41 hypersensitive teeth were selected at Department of Dentistry, Chang Gung Memorial Hospital at Kaohsiung, from September 1992 to March 1993. Sensitivity scales were measured as follows: (1) 0-no pain; (2) 1-mild pain; (3) 2-moderate pain; (4) 3-severe pain; (5) 4-pain continued after removal of stimulus. Both air blast and cold water stimuli were tested before and after using the new desensitizing agent. The response of each tooth was also compared before and after treatment according to each scale. The results showed that 30% potassium oxalate gel had a significant reduction in the responses to air blast and cold water (p < 0.05), suggesting that 30% potassium oxalate gel may be another agent of choice for tooth desensitization.

Adult↗
PubMed1995

Interaction of streptokinase and plasminogen. Studied with truncated streptokinase peptides.

The interaction of streptokinase (SK) with human plasminogen (HPlg) was investigated using truncated SK peptides prepared by gene cloning techniques. SK(16-414) and SK(16-378) could activate HPlg as efficiently as the authentic SK. SK(60-414), which had been preincubated with SK(1-59), could also activate HPlg. SK(91-414), SK(127-414), and SK(158-414), at a concentration of one-tenth of HPlg, all failed to activate HPlg. However, the truncated SK peptides in complexes with equimolar HPlg could form amidolytically active virgin enzymes that slowly converted to human plasmin (HPlm) after a lag period of 15 min. SK(16-316) could not activate HPlg. No virgin enzyme was detected when SK(16-316) was incubated with equimolar HPlg, but the HPlg in the complex was modified to HPlm after reaction for 20 min. SK(220-414) and SK(16-251) had no ability to transform HPlg to virgin enzyme or to HPlm in equimolar complex with HPlg, although they could bind to HPlg. The functions of five regions in the SK molecule (a, Ile1-Lys59; b, Ser60-Asn90; c, Val158-Arg219; d, Tyr252-Ala316; e, Ser317-Ala378) in interaction with HPlg are deduced. Region a is important in stabilizing the conformation of the SK molecule, and region b is essential for HPlg activation. Region c is required for induction of the conformational changes of HPlg to virgin enzyme. Regions c and d are required for the conversion of HPlg to HPlm in the HPlg.SK equimolar complex. Coordination of regions c, d, and e of SK is essential for a virgin enzyme formation, and coordination of regions b, c, d and e is required for an effective SK-type HPlg activator.

Base Sequence↗
PubMed1995

Inhibition of plasma extravasation by abruquinone A, a natural isoflavanquinone isolated from Abrus precatorius.

Polymyxin B-induced hind-paw edema was suppressed by abruquinone A, an isoflavanquinone isolated from Abrus precatorius, in normal as well in adrenalectomized mice. Unlike dexamethasone, abruquinone A did not increase the liver glycogen content in fasting adrenalectomized mice. The volume of exuded plasma was significantly reduced by abruquinone A in neurogenic inflammation, passive cutaneous anaphylactic reaction and compound 48/80-induced ear edema. Histamine-, serotonin-, bradykinin- and substance P-induced plasma extravasation in ear edema was also suppressed by abruquinone A. Abruquinone A, like isoproterenol, significantly reduced the bradykinin- and substance P-induced plasma extravasation in normal as well as in compound 48/80-pretreated mice. In addition, abruquinone A suppressed the bradykinin- and substance P-induced ear edema to a significantly greater extent than diphenhydramine/methysergide did. In the in vitro experiments, abruquinone A suppressed the compound 48/80-induced histamine and beta-glucuronidase released from isolated rat peritoneal mast cell preparations. These results suggest that the anti-inflammatory effect of abruquinone A is mediated partly via the suppression of the release of chemical mediators from mast cells and partly via the prevention of vascular permeability changes caused by mediators. The glucocorticoid activity and the release of glucocorticoid hormones from the adrenal gland are probably not involved.

Adrenalectomy↗
PubMed1995

Inhibition of hind-paw edema and cutaneous vascular plasma extravasation in mice by acetylshikonin.

Acetylshikonin, a naphthoquinone isolated from the Chinese herb medicine, tzu ts'ao, was demonstrated to inhibit the polymyxin B-induced hind-paw edema in normal as well as in adrenalectomized mice. Liver glycogen content was increased in adrenalectomized mice pretreated with dexamethasone, but not with acetylshikonin. Like diphenhydramine, methysergide and isoproterenol, acetylshikonin reduced the plasma exudation evoked in dorsal hind-paw skin by antidromic stimulation of the saphenous nerve, and in passive cutaneous anaphylactic reaction, bradykinin-, substance P-, compound 48/80-, histamine- and serotonin-induced ear edema. Indomethacin was ineffective in these respects. Bradykinin- and substance P-induced plasma exudation were also significantly reduced when [Thi5,8,D-Phe7]bradykinin and [D-Pro2,D-Trp7,9]substance P were coinjected with bradykinin and substance P, respectively. In isolated rat peritoneal mast cell preparation, acetylshikonin produced a concentration-dependent inhibition of histamine and beta-glucuronidase release from mast cells challenged by compound 48/80. In compound 48/80-pretreated mice, acetylshikonin and isoproterenol produced significantly more inhibitory effect on bradykinin- and substance P-induced plasma exudation than did diphenhydramine in combination with methysergide. Pretreatment with diphenhydramine/methysergide in compound 48/80-pretreated mice significantly further reduced the bradykinin- and substance P-induced plasma exudation if [Thi5,8,D-Phe7]bradykinin and [D-Pro2,D-Trp7,9]substance P were coinjected with bradykinin or substance P, respectively. The results suggest that the inhibitory effect of acetylshikonin on the edematous response is due neither to the release of steroid hormones from the adrenal gland nor to the glucocorticoid activity, but probably partly to the suppression of mast cell degranulation and partly to protection of the vasculature from mediator challenge.

Adrenalectomy↗
PubMed1995

Degenerative lumbar spinal stenosis. Diagnostic value of the history and physical examination.

OBJECTIVE: To assess the value of the history and physical examination findings in the diagnosis of symptomatic degenerative lumbar spinal stenosis (LSS). METHODS: The study was performed in 3 specialty clinics, and included patients with low back pain who were at least age 40. Findings from a standardized history and physical examination were compared with the diagnostic impression of expert attending clinicians. Imaging studies were available in 88% of those with LSS, and the findings further supported the diagnosis of LSS in each case. The sensitivity, specificity, and likelihood ratio associated with each history and physical examination finding were calculated in bivariate analyses, and independent correlates of LSS were identified with multivariate analyses. RESULTS: Ninety-three patients were evaluated. History findings most strongly associated with the diagnosis of LSS (likelihood ratio > or = 2) were greater age, severe lower-extremity pain, and absence of pain when seated. Physical examination findings most strongly associated with the diagnosis were wide-based gait, abnormal Romberg test result, thigh pain following 30 seconds of lumbar extension, and neuromuscular deficits. Independent correlates of LSS included advanced age (P = 0.0001), absence of pain when seated (P = 0.006), wide-based gait (P = 0.013), and thigh pain following 30 seconds of lumbar extension (P = 0.002). CONCLUSION: Specific history and physical examination findings are useful in the diagnosis of LSS and should be ascertained routinely in older patients with low back pain.

Adult↗
PubMed1995

Solid state characterization of dehydroepiandrosterone.

Three polymorphs (forms I-III), a monohydrate (form S2), and three new solvates [4:1 hydrate (form S1), monohydrate (form S3), and methanol half-solvate (form S4)] were isolated and characterized by X-ray powder diffractometry (XRPD), IR spectroscopy, differential scanning calorimetry (DSC), hot stage microscopy, solution calorimetry, and their dissolution rates. A new polymorph, designated as form V, melting at 146.5-148 degrees C, was observed by hot stage microscopy. Our results indicate that only forms I and S4 exhibit reproducible DSC thermograms. Five of the isolated modifications undergo phase transformation on heating, and their DSC thermograms are not reproducible. Interpretation of DSC thermograms was facilitated by use of hot stage microscopy. The identification of each modification is based on XRPD patterns (except forms S3 and S4, for which the XRPD patterns are indistinguishable) and IR spectra. In the IR spectra, a significant difference was observed in the OH stretching region of all seven modifications. In a purity determination study, 5% of a contaminant modification in binary mixtures of several modifications could be detected by use of XRPD. To obtain a better understanding of the thermodynamic properties of these modifications, a series of increasing heating rates and different pan types were used in DSC. According to Burger's rule, forms I-III are monotropic polymorphs with decreasing stability in the order form I > form II > form III. The melting onsets and heats of fusion for forms I-III are 149.1 degrees C, 25.5 kJ/mol; 140.8 degrees C, 24.6 kJ/mol; and 137.8 degrees C, 24.0 kJ/mol, respectively. For form III the heat of fusion was calculated from heat of solution and DSC data. In the case of form S1 the melting point, 127.2 degrees C, was obtained by DSC using a hermetically sealed pan. The relative stabilities of the six modifications stored under high humidity conditions were predicted to be, on the basis of the heat of solution and thermal analysis data, from S2 > form S3 > form S1 > form I > form II > form III. However, the results of the dissolution rate determination were inconsistent with the heat of solution data. The stable form I shows a higher initial dissolution rate than the metastable form II and unstable form III. All modifications were converted into the stable monohydrate, form S2, during the dissolution study, suggesting that the moisture level in solid formulations should be carefully controlled.

Calorimetry, Differential Scanning↗
PubMed1995

RT/PCR detection of SIL-TAL-1 fusion mRNA in Chinese T-cell acute lymphoblastic leukemia (T-ALL).

The TAL-1 gene is located on chromosome 1p32. In about 20% of T-cell acute lymphoblastic leukemias (T-ALL), this gene is disrupted in its 5' portion by a site-specific 100-kg deletion and is fused with the 5' part of the SIL gene, to form SIL-TAL-1 chimeric gene. In this study, we established a "nested" retrotranscriptase/polymerase chain reaction (RT/PCR) technique which allows detection of the SIL-TAL-1 transcriptional expression. A chimeric mRNA was observed in four of 17 T-ALL cases and has been shown to result from the fusion between the exon 1 of SIL and exon 3 of TAL. A sensitivity test showed that this RT/PCR procedure could detect one leukemic cell among 10(6) normal cells. A positive RT/PCR result was obtained in two cases during clinical remission, suggesting the presence of minimal residual disease (MRD). One patient developed clinical relapse 3 months after PCR positivity. Moreover, analysis of the Tald rearrangement by DNA-based PCR in four patients with SIL-TAL-1 fusion revealed the type A (Tald1) rearrangement in all cases. Sequence analysis demonstrated the presence of N region and non-random "P" nucleotide, as well as base deletions at the genomic SIL-TAL-1 joining site. These data indicate that detection of TAL-1 gene abnormality is important for diagnosis and monitoring of MRD in a subset of T-ALL.

Adolescent↗
PubMed1995

Anti-inflammatory effect of magnolol, isolated from Magnolia officinalis, on A23187-induced pleurisy in mice.

In the present study, A23187-induced pleurisy in mice was used to investigate the anti-inflammatory effect of magnolol, a phenolic compound isolated from Chinese medicine Hou p'u (cortex of Magnolia officinalis). A23187-induced protein leakage was reduced by magnolol (10 mg kg-1, i.p.), indomethacin (10 mg kg-1, i.p.) and BW755C (30 mg kg-1, i.p.). A23187-induced polymorphonuclear (PMN) leucocyte infiltration in the pleural cavity was suppressed by magnolol and BW755C, while enhanced by indomethacin. Like BW755C, magnolol reduced both prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels in the pleural fluid of A23187-induced pleurisy, while indomethacin reduced PGE2 but increased LTB4 formation. In the rat isolated peripheral neutrophil suspension, magnolol (3.7 microM) and BW755C (10 microM) also suppressed the A23187-induced thromboxane B2 (TXB2) and LTB4 formation. These results suggest that magnolol, like BW755C, might be a dual cyclo-oxygenase and lipoxygenase inhibitor. The inhibitory effect of magnolol on the A23187-induced pleurisy is proposed to be, at least partly, dependent on the reduction of the formation of eicosanoids mediators in the inflammatory site.

Animals↗
PubMed1995

Differential responses of hormone-sensitive lipase gene to nutritional transition in adipose tissue, liver, and skeletal muscle of pigs.

To study the regulation of hormone-sensitive lipase gene in pigs, we amplified and sequenced partial porcine hormone-sensitive lipase cDNA. Nucleotide analysis indicated that porcine hormone-sensitive lipase cDNA was 86% homologous with the rat. In agreement with the rat, a 3.3 kb mRNA transcript was detected in adipose tissue but not in skeletal muscle of pigs by Northern hybridization. With more sensitive PCR method, hormone-sensitive lipase mRNA was found in adipose tissue, liver, heart, skeletal muscle, testis, and spleen. The gene expression in adipose tissue and liver was elevated after 2 days of fasting, and refeeding for another 2 days decreased the mRNA abundance. In contrast, the levels in skeletal muscle were not altered during identical nutritional transition. Combined evidences suggest that differential control may occur in porcine hormone-sensitive lipase gene in a tissue-specific fashion.

Adipose Tissue↗
PubMed1994

Triosephosphate isomerase requires a positively charged active site: the role of lysine-12.

The role of lysine-12 at the active site of yeast triosephosphate isomerase has been elucidated by a combination of site-directed mutagenesis, Fourier transform infrared spectroscopy, enzyme kinetics, and X-ray crystallography. Several lines of evidence suggest that the mutant isomerase in which lysine has been changed to methionine cannot bind substrate. This mutant enzyme has no detectable catalytic activity, and infrared experiments show no evidence of binding dihydroxyacetone phosphate nor dihydroxyacetone sulfate to the active site. Furthermore, crystals of the enzyme grown in the presence of phosphoglycolohydroxamate, a potent reaction intermediate analog, show an open active site with no inhibitor bound. Mutation of lysine-12 to arginine produces a protein with a value Km elevated by a factor of 22, a Vmax reduced by a factor of 180, and a Ki for phosphoglycolohydroxamate elevated by a factor of 290. Mutation of lysine-12 to histidine produces an enzyme that shows virtually no catalytic activity at neutral pH, but below pH 6.1 this enzyme is active, suggesting that protonation of the histidine in this mutant is required for activity. These studies, together with the structural results reported in an accompanying paper, provide convincing evidence that a positive charge is required for substrate binding at the active site of triosephosphate isomerase and that lysine-12 provides this positive charge.

Amino Acid Sequence↗