Biomedical subjects

S Y Chang

Publications and source records attributed to S Y Chang.

At least 109 records · Page 6Linked to original sources

PubMed1999

Isolation and characterization of cDNA clone for human liver 10-formyltetrahydrofolate dehydrogenase.

A cDNA clone encoding 10-formyltetrahydrofolate dehydrogenase (10-FTHFDH) was isolated from a human fetal liver cDNA library. It contained the open reading frame of 2,709 base pairs and predicted a protein comprising 902 amino acids with a calculated molecular weight of 98,700 Da. The deduced protein showed about 93.6% homology (90.5% identity, 3.1% favored substitutions) when compared with rat 10-FTHFDH. The distribution of 10-FTHFDH transcript in various human tissues was studied by Northern blot analysis using poly(A+) RNAs from different tissues. The 10-FTHFDH transcript with an approximate size of 2.7 kb was mainly expressed in human kidney, skeletal muscle, and liver and rarely expressed in other tissues.

Amino Acid Sequence↗

PubMed1999

Comparison of sliced and whole lung sets for the LLNL and JAERI torso phantoms using GE detectors.

The performance characteristics of sliced lung sets were compared to lung sets with activity homogeneously distributed throughout the lung tissue substitute material. The activity estimate from planar sources differs from the estimate from homogeneous sources by a factor of 0.88 to 1.09 depending on the photon energy. This error is small compared to other uncertainties commonly encountered in lung counting, i.e., activity deposition in the lung, detector placement, size difference between individuals, etc. Sliced lung sets could be used instead of homogeneous lung sets to test or provide an interim calibration for a lung counting system.

Calibration↗

PubMed1999

Contralateral hemilaryngotracheal flap reconstruction of the hypopharynx in pyriform carcinoma resection.

OBJECTIVES: To simplify the approach and reconstruction for advanced hypopharyngeal cancer, a modified technique-laryngotracheal fissure approach and laryngotracheal flap reconstruction--is presented. STUDY DESIGN: Prospective. METHODS: From August 1991 to December 1995, 44 consecutive patients with advanced hypopharyngeal cancer, mostly involving pyriform sinus, were operated on with this technique. The functional and oncologic results and complications were evaluated. RESULTS: Reconstruction was completed by using the laryngotracheal flap in 75% of patients, while the other 25% required additional patch-on pectoralis major myocutaneous flaps. Pharyngoesophageal stenosis occurred in one patient after radiotherapy and pharyngocutaneous fistula was noted in two. No local recurrence was noted. Seven cervical metastases developed in the follow-up period and six over the contralateral neck not treated surgically. The 5-year Kaplan-Meier disease-free survival was 46.8%. CONCLUSIONS: The authors' experience indicates that this is a simplified, radical treatment for most advanced hypopharyngeal cancer, with high applicability, good oncologic results, and low complication.

Adult↗

PubMed1999

Prefabrication of jejunum for challenging reconstruction of cervical esophagus.

A significant benefit exists for a jejunal replacement of the cervical esophagus, if indicated. The absence of available recipient vessels may impede free tissue transfer. If vascular induction between a vascular carrier and the selected jejunal segment is done as a kind of flap prefabrication, the jejunal interposition flap can be used without the need for complex microsurgery.

Adult↗

PubMed1999

Effect of capsaicin on the micturition reflex in normal and chronic spinal cord-injured cats.

The effect of capsaicin (10-80 mg/kg sc) on reflex activity of the urinary bladder was examined in anesthetized normal as well as anesthetized and awake chronic spinal cord-injured (SCI) cats. In normal cats, capsaicin elicited a transient increase in the frequency of isovolumetric bladder contractions and reduced the volume threshold for inducing micturition, but did not depress the amplitude of bladder contractions or the reflex firing on bladder nerves. In anesthetized SCI cats, capsaicin depressed reflex bladder activity and firing on bladder nerves. In awake SCI cats, capsaicin initially decreased the volume threshold for inducing micturition; however, after a delay of 3-6 h the volume threshold increased and intravesical voiding pressure decreased. This effect persisted for 4-12 days. It is concluded that capsaicin-sensitive C fiber bladder afferents are not involved in initiating reflex micturition in normal cats, but play an essential role in triggering automatic micturition in chronic SCI cats. The results are consistent with the clinical data indicating that C fiber bladder afferents contribute to bladder hyperactivity and incontinence in patients with neurogenic bladder dysfunction.

Animals↗

PubMed1999

Flow-cytometric measurement of cellular changes in urine: a simple and rapid method for perioperatively monitoring patients after kidney transplantation.

OBJECTIVE: In renal transplant patients having graft dysfunction, it is usually difficult to obtain the accurate diagnosis, such as acute rejection, acute tubular necrosis, infection, or cyclosporin nephrotoxicity. An accurate diagnosis can provide the proper treatment of these patients, thereby lessening the chance of kidney loss. METHODS: A total of 42 patients were enrolled. By using the flow-cytometric technique, the white cell populations of urine in these patients were analyzed and linked to their clinical course. All patients underwent sonography-guided biopsy of the transplanted kidney with a definitive diagnosis. RESULTS: When 10% lymphocytes and 15% granulocytes in urine were set as the cutoff point of a normal ratio threshold, the flow-cytometric analysis presented the highest sensitivity and the highest negative predictive rate for acute tubular necrosis. However, a lower sensitivity and positive predictive rate was found in acute rejection cases. CONCLUSIONS: Our results suggest that flow-cytometric analysis of the urinary cell population can be used as an adjunct in patient follow-up after kidney transplantation.

Acute Disease↗

PubMed1999

Fosinopril and hydrochlorothiazide combination versus individual components: lack of a pharmacokinetic interaction.

OBJECTIVE: To evaluate the pharmacokinetic interaction and bioequivalence of a combination formulation of the angiotensin-converting enzyme inhibitor fosinopril and the diuretic hydrochlorothiazide (HCTZ). METHODS: In an open-label, balanced, randomized incomplete block, three-way crossover fashion, healthy men received single doses of three of four regimens in one of two independent studies. Regimens for study A (36 subjects): (1) fosinopril 10-mg tablet, (2) HCTZ 12.5-mg tablet, (3) a combination tablet of fosinopril 10 mg plus HCTZ 12.5 mg, or (4) coadministered tablets of fosinopril 10 mg and HCTZ 12.5 mg. Study B (40 subjects) received: (1) fosinopril 20-mg tablet, (2) HCTZ 12.5-mg tablet, (3) a combination tablet of fosinopril 20 mg plus HCTZ 12.5 mg, or (4) coadministered tablets of fosinopril 20 mg and HCTZ 12.5 mg. RESULTS: There was no evidence of any significant effect of HCTZ on the pharmacokinetics of fosinoprilat, based on maximum concentration value, AUC, or cumulative urinary recovery over 24 hours. Fosinoprilat had no clinically important effect on the pharmacokinetics of HCTZ only slightly decreasing its AUC by 14% in study A. Coadministration was well tolerated; no new adverse events were reported with the combination tablet. CONCLUSIONS: Fosinopril and HCTZ in a combination tablet display pharmacokinetic profiles similar to those achieved when either drug is administered alone or when coadministered in separate tablets. When used with HCTZ, the favorable pharmacokinetic feature of fosinopril, dual and compensatory pathways of renal and hepatic elimination, is preserved.

Adolescent↗

PubMed1999

Nucleotide and peptide sequences of the open reading frame encoding a truncated toxin A gene of Clostridium difficile strain CCUG 20309.

The open reading frame encoding a putative truncated toxin A gene of Clostridium difficile in strain CCUG 20309 (ATCC 8864), a strain that produces toxin B but not toxin A, was sequenced by cycle sequencing method. The coding region contains 2097 base pairs and has a GC content of 26.4%. The deduced polypeptide is 50 kDa and is generally hydrophilic. Although strain CCUG 20309 of C. difficile was reported not to produce toxin A, it is enterotoxic, an inherent property of toxin A in pathogenic strains of C. difficile. It therefore remains to be determined whether a truncated form of toxin A could actually be expressed from the open reading frame by this strain of C. difficile.

Amino Acid Sequence↗

PubMed1999

Effects of short-course buserelin therapy on adenomyosis. A report of two cases.

BACKGROUND: Hysterectomy and hysteroscopic endometrial ablation remain common treatment of symptomatic adenomyosis for women who have completed childbearing. However, for patients who wish to avoid surgery and in whom adenomyosis is suspected of causing infertility, repeated abortion or physical symptoms, medical treatment with gonadotropin-releasing hormone analogue (GnRH-a) should be considered. CASES: Two cases of documented adenomyosis were suspected of causing infertility; both were treated with a three-month course of GnRH-a via a nasal spray. Both patients experienced relief of symptoms and conceived within six months of the cessation of treatment. CONCLUSION: The efficacy and safety of a short course of GnRH-a treatment of adenomyosis may be considered in patients who take less time than others to achieve a significant reduction of uterine size and relief of symptoms and in those who develop side effects.

Administration, Intranasal↗

PubMed1999

Multiple pregnancy with adnexal torsion after in vitro fertilization: case report.

Assisted reproductive techniques (ART) are widely accepted procedures for infertile couples. Rare complications, like heterotopic pregnancy, bilateral tubal pregnancy, and adnexal torsion during pregnancy, have been diagnosed with increasing frequency after ART. We present a case of an early triplet pregnancy complicated with adnexal torsion. The patient was pregnant through in vitro fertilization. Early ultrasound examination revealed a triplet pregnancy within the uterine cavity. At 7 weeks' gestational age, an acute onset of lower abdominal pain, progressive abdominal distension, and massive internal bleeding prompted emergency laparotomy. The right ovary was enlarged, twisted, necrotic and hemorrhagic. Attempts to preserve the ovary failed because of the friable nature of the affected ovary, and an oophorectomy had to be performed. Although the removed ovary contained a corpus luteum, the pregnancy continued smoothly after only short luteal support. A precise pre-surgery diagnosis in our case was difficult based on the patient's initial clinical presentation. However, with high clinical suspicion in addition to color Doppler ultrasound, the physician should be able to make an early decision for an exploratory laparotomy or laparoscopy, gaining the benefit of more conservative treatment.

Adnexal Diseases↗

PubMed1999

Retinal detachment in postpartum preeclampsia and eclampsia: report of two cases.

Retinal detachment is an unusual complication of hypertensive disorder in pregnancy. It has been reported in 1% to 2% of patients with severe preeclampsia and in 10% of patients with eclampsia. Choroidal ischemia may be the cause of retinal detachment. We know that mild arteriolar spasm involving the bulbar conjunctival vessels has been observed in the normal pregnancy, but in pregnancy-induced hypertension the vasospasm may be severe and result in choroidal ischemia. Most patients with retinal detachment in pregnancy-induced hypertension have had full spontaneous resolution within a few weeks, and they did not have any sequelae. Medical treatment with antihypertensive drugs and steroids may be helpful. We report two rare cases of retinal detachment and persistent hypertension in association with postpartum eclampsia and post-cesarean section preeclampsia. These patients had normotension throughout pregnancy. Preeclampsia or eclampsia developed after delivery, and blurred vision, headache, and reduced vision accompanied serous retinal detachment. The serous retinal detachment disappeared within 3 weeks. Good outcomes were found in the follow-up examinations in both of these cases. For women who had been normotensive at the time of delivery and then complained in the postpartum period of blurred vision, headaches, nausea and vomiting, we should consider the possibility of retinal detachment and perform fundoscopy.

Adult↗

PubMed1999

[Development of a multi-channel physiological telemetry system].

OBJECTIVE: To develop an instrument used in measurement of physiological parameters in laboratories or field. Method A: computer was used to process data in the telemetry system. The frequency-time division modulation technique was adopted. The low frequency signals were directly connected to the computer serial port after demodulation, and measurement control was achieved by single-chip computer. Temperature measurement results were obtained by conversion table. RESULT: It is capable of telemeter and processing ECG, wind speed and temperature signals in real-time. Good results were gained in high temperature condition and -17 degrees C environment. CONCLUSION: The instrument has many advantages, such as high accuracy, good processing ability, reliability, long operation distance, small volume and easy operation.

Aerospace Medicine↗

PubMed1999

[Thermal physiological analysis of man in an Intravehicular Activity space suit].

OBJECTIVE: To analyze the thermal physiological changes of man in a Intravehicular Activity (IVA) space suit. METHOD: Combined second design was used to arrange 24 tests in 6 young male subjects wearing an IVA space suit at sea level. RESULT: The relationship between common thermal physiological measurements and air ventilating parameters (air temperature, flow rate and its relative humidity) together with metabolic state (rest or work) of man were established in mathematical models. Possible applications of these models were illustrated. Metabolic heat production which influences the relations was also discussed. CONCLUSION: Thermal physiological changes of man in the space suit were properly expressed by the mathematical models in this paper.

Adolescent↗

PubMed1998

Virological and immunological features of long-term human immunodeficiency virus-infected individuals who have remained asymptomatic compared with those who have progressed to acquired immunodeficiency syndrome.

Infection with the human immunodeficiency virus (HIV) leads to a decrease in CD4(+) T cells and disease progression within a decade of seroconversion. However, a small group of infected people, despite being infected by HIV for 10 or more years, remain clinically asymptomatic and have stable CD4(+) cell counts without taking antiretroviral medication. To determine why these individuals, known as long-term survivors (LTS), remain healthy, the hematological profiles, viral load and properties, HIV coreceptor genotype, and anti-HIV immune responses of these people were compared with those of individuals who have progressed to disease (Progressors) over the same time period. Unlike Progressors, LTS have a low circulating viral load and a low number of HIV-infected cells. These differences in the levels of the viral load were not associated with a dominant biologic viral phenotype, varying growth kinetics of the virus, mutation in the cellular CCR5 gene, or the presence of neutralizing antibodies. Importantly, the difference in viral load could be explained by the enhanced ability of CD8(+) cells from LTS to suppress HIV replication.

Acquired Immunodeficiency Syndrome↗

PubMed1998

High-performance liquid chromatography with a column-switching system and capillary electrophoresis for the determination of ibuprofen in plasma.

Quantitative aspects of high-performance liquid chromatography with a column-switching system (CSS-HPLC) and capillary electrophoresis (CE) were investigated for the determination of ibuprofen in plasma. For CSS-HPLC, 100 microl of plasma was directly injected onto the column system for the three separation steps: (1) deproteinization and fractionation of plasma samples with a polymer-coated mixed-function phase column, (2) concentration with an intermediate column and (3) final separation with a main column. For CE, a mixture of 50 microl of plasma and 1 ml of acetonitrile was centrifuged and the supernatant was introduced onto the capillary (66 cmX50 microm I.D.; 62 cm to detector) at 20 degrees C. Run buffer was 250 mM sodium borate buffer (pH 8.5) and applied electric field was 379 V cm(-1). Linear dynamic ranges were 0.1-250 microg ml(-1) in CSS-HPLC and 1-1000 microg ml(-1) in CE. Intra-day and inter-day coefficients of variation were less than 5.6% and 6.5% for CSS-HPLC, 6.3% and 6.5% for CE, respectively. The limits of detection (S/N=3) for CSS-HPLC and CE were 25 ng ml(-1) and 300 ng ml(-1), respectively. CSS-HPLC was superior in simplicity and sensitivity, while CE was better in efficiency, rapidity, and cost.

Animals↗

PubMed1998

Isolation of cDNA clones encoding human histone macroH2A1 subtypes.

cDNA clones encoding two different subtypes of histone macroH2A1, macroH2A1.1 and macroH2A1.2, have been isolated from human liver tissue. The open reading frames in the isolated clones predicted proteins comprising 368 and 371 amino acids respectively. Estimated molecular masses of the two proteins were 39.0 kDa and 39.4 kDa. Human histone macroH2A1.1 and macroH2A1.2 showed about 98% identity with their counterparts isolated from rat. The features of the nucleotide sequences of the two macroH2A1 subtypes in human were the same as in the rat system. Northern blot analysis showed that the macroH2A1.1 and macroH2A1.2 subtypes were expressed as mRNA species with a size of 1.5 and 4.4 kb, respectively. They were expressed in all human tissues examined.

Amino Acid Sequence↗

PubMed1998

Prenatal diagnosis of de novo interstitial deletion of proximal 4q by maternal serum screening for Down syndrome.

Deletion of the proximal portion of chromosome 4q is apparently rare. To our knowledge, prenatal diagnosis of the interstitial deletion of 4q12-21.1 has never been reported. We present a prenatal case of 4q deletion in association with a positive Down syndrome screening test of an elevated maternal serum free beta human chorionic gonadotrophin (beta-hCG) level. The prenatal sonogram revealed intra-uterine growth retardation (IUGR) and shortening of the femur. Facial dysmorphism included micrognathia, depressed nasal bridge and low-set ears, these anomalies were evident at the postnatal examination. All of the anomalies were consistent with those described in proximal 4q deletion syndrome. Our case suggests that chromosome studies may be indicated for patients with high maternal serum free beta-hCG and IUGR in the early second trimester.

Adult↗

PubMed1998

Monoclonal antibodies against renal tumors: the potential application in discrimination of ambiguous adenocarcinoma or transitional cell carcinoma of kidney.

PURPOSE: We tested the discrimination ability of 2 monoclonal antibodies, mAB 90 and 2-2, in renal carcinomas, including renal cell carcinoma and transitional cell carcinoma of the kidney. MATERIALS AND METHODS: Two monoclonal antibodies raised in renal adenocarcinoma (mAB 90, IgG3 subclass and mAB 2-2, IgG1 subclass), have been generated in our laboratory by hybridoma technique. The tumor associated antigens recognized by these IgG subclass monoclonal antibodies are located in the cell membrane of tumor cells. Antibodies were purified from mice ascites through protein A-Sepharose 4B affinity column and then conjugated with fluorescein isothiocyanate fluorescence by dimethyl sulfoxide method. The binding activity of these antibodies was measured by direct immunofluorescence method and analyzed in a flow cytometer. Forty-five cases of renal cell carcinoma and 16 cases of transitional cell carcinoma of the renal pelvis were collected, and the recognition power of these 2 antibodies was tested. Frozen tumor tissues were prepared and allocated into single cell suspensions in phosphate buffered saline before adding diluted (1:10) conjugated antibodies. Irrelevant antibody and negative tumor cell lines without any reaction with these antibodies were used as background fluorescence control. RESULTS: Reactivities of mAB 90 and mAB 2-2 for renal cell carcinoma tissues were 80 and 91%, respectively. On the contrary the reactivities of mAB 90 and mAB 2-2 for transitional cell carcinoma of renal pelvis tissues were 0 and 69%, respectively. mAB 90 (+)/mAB 2-2 (-) expression pattern had 76% accurate diagnostic rate for renal cell carcinoma and mAB 90 (+)/mAB 2-2 (+) pattern had 69% accurate diagnostic rate for transitional cell carcinoma of the kidney. CONCLUSIONS: When facing pathologically ambiguous kidney tumors, the binding specificity of mAB 90 and mAB 2-2 may be useful for discrimination between renal cell carcinoma tumors and transitional cell carcinoma of the renal pelvis.

Antibodies, Monoclonal↗