Search PubMed⌕ Search

Biomedical subjects

S C Huang

Publications and source records attributed to S C Huang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Functional CCK-A and Y2 receptors in guinea pig esophagus.

Effects of cholecystokinin octapeptide (CCK-8), peptide YY (PPY), neuropeptide Y (NPY) and their analogs on muscle contractions of esophageal strips were investigated. CCK-8 induced a tetrodotoxin and atropine-sensitive contraction. The relative potencies for CCK related peptides to induce contractions were CCK-8 > desulfated CCK-8 > gastrin-17-I. The CCK-A receptor antagonist L-364,718 was 300-fold more potent than the CCK-B receptor antagonist L-365,260 at inhibiting CCK-8-induced contraction. These indicate that neural CCK-A receptors mediate this contraction. PYY or NPY did not cause muscle contraction or inhibit muscle contraction induced by carbachol, endothelin-1 or KCl. However, both PYY and NPY concentration-dependently inhibited contraction induced by CCK-8. This inhibition was not affected by nitric oxide (NO) synthase inhibitors L-NMMA or L-NAME. The relative potencies of PYY related peptides to inhibit CCK-8 induced contraction were PYY > NPY > NPY13-36 > [Leu(31), Pro(34)]NPY > pancreatic polypeptide (PP). We conclude that CCK interacts with neural CCK-A receptors to cause esophageal muscle contraction. PYY and NPY interact with Y2 receptors to inhibit this CCK-induced muscle contraction by an effect not related to NO.

Animals↗
PubMed2000

Echocardiographic evaluation of cardiac rhabdomyoma in infants and children.

PURPOSE: The objective of this study was to demonstrate the clinical presentation, echocardiographic findings, and morbidity and mortality rates for cardiac rhabdomyoma in Chinese infants and children by using echocardiography. METHODS: Two-dimensional echocardiography was performed at our institution from 1992 through 1999 on 12,800 children under 15 years of age. The diagnoses of cardiac rhabdomyoma were made primarily by echocardiography based on the presence of multiple tumors, cardiac tumors associated with tuberous sclerosis (TS), or histopathologic examination of surgical specimens. All patients were evaluated with 2-dimensional and Doppler echocardiography and then on follow-up examination every 3-6 months. Complete tumor regression was defined as no tumor visible by echocardiography. Partial tumor regression was defined as a decrease in tumor size of at least 15% from the previously measured size. RESULTS: A total of 29 tumors were found in 11 patients, 8 of whom had either TS or a family history of TS in 1 or more first-degree relatives. There were 9 boys and 2 girls 1 day-6.5 years old; (mean, 1.1 years). Three patients (newborns with heart failure) died, 2 after emergency surgery and 1 of intractable heart failure. The remaining 8 patients were managed conservatively and monitored for a mean duration of 3.3 years. Follow-up studies revealed that, of the 22 tumors in these 8 patients, 7 completely regressed, 7 partially regressed, and 8 remained stable. Our results showed no relationship between the tumor location and the regression rate (p = 0.34). CONCLUSIONS: Cardiac rhabdomyoma often presents in TS patients with no major arrhythmia or hemodynamic obstruction. However, in symptomatic neonates with or without TS, cardiac rhabdomyoma is usually fatal. Meticulous prenatal screening and routine echocardiographic examinations of patients with TS can reveal subclinical or clinically occult cardiac rhabdomyomas.

Adolescent↗
PubMed2000

Mid-trimester beta-hCG levels incorporated in a multifactorial model for the prediction of severe pre-eclampsia.

Pre-eclampsia remains a major cause of perinatal morbidity and mortality worldwide. Proposed predicting tests for early detection of pregnant women destined to develop pre-eclampsia remain unsatisfactory. The aim of this study was to investigate the clinical utility of combining mid-trimester maternal serum beta-human chorionic gonadotrophin (MShCG) levels with selected clinical determining factors as a multifactorial predictive test for pre-eclampsia. Thirty-nine cases with mild pre-eclampsia and 56 with severe pre-eclampsia were recruited as the study groups. Normotensive women (957) were enrolled as controls. Potential determining risk factors for severe pre-eclampsia were selected using a multiple logistic regression to build various combined prediction models. A receiver-operator characteristic curve was employed to assess the performance of each prediction test for pre-eclampsia. The prediction efficacy of each test was examined by the area under the curve (AUC). Our data show that mid-trimester MShCG levels significantly correlated with severity of pre-eclampsia (Spearman rank correlation coefficient=0.195, p<0.001). Women with mild pre-eclampsia had a 2.61-times greater chance, while women with severe pre-eclampsia had a 6.13-times greater chance of having MShCG exceeding 2.0 multiples of the median than did women with a normal pregnancy. A combined prediction model composed of MShCG levels, body mass index (BMI), parity, and age as a predictive test for severe pre-eclampsia was superior to MShCG levels alone (AUC 0.765 versus 0.648). The integrated multifactorial model could identify women at risk early on for developing severe pre-eclampsia, with a sensitivity of 70% and a specificity of 71%. Thus, we demonstrate a potentially effective and convenient method by which women at risk for developing severe pre-eclampsia can be identified early, based on a multifactorial predictive model composed of midtrimester MShCG levels, BMI, parity, and age.

Adult↗
PubMed2000

Effects of menopause and obesity on lipid profiles in middle-aged Taiwanese women: the Chin-Shan Community Cardiovascular Cohort Study.

In this cross-sectional study, we examined the associations between lipid profiles and menopausal status, age, and obesity in Taiwanese women. The study population, established in 1990-91, consisted of 671 premenopausal and 872 postmenopausal women from the Chin-Shan Community Cardiovascular Cohort (CCCC). The associations of age, body mass index (BMI), and menopausal status with serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), apoproteins (Apo) A-1 and B, and lipoprotein (a) [Lp (a)] were evaluated. The results showed that menopause was associated with significant increases in TC, LDL-C, TG, and Apo B levels (all P < 0.001). Total cholesterol, LDL-C, TG, and Apo B levels increased consistently with BMI in middle-aged women, regardless of menopausal status. Among women aged 45-49, menopausal women had significantly higher levels of TC and LDL-C than premenopausal women (P < 0.01). However, TG and Apo B levels were higher in postmenopausal than in premenopausal women aged 50-54 years (P < 0.05). Standardized regression analyses showed all lipid variables, except those of Apo A1 and Lp (a) before menopause and TC, LDL-C, and Lp (a) after menopause, were significantly associated with BMI (all P < 0.01). We conclude serum lipid levels in Taiwanese women are no more strongly associated with menopause and BMI than with age.

Adult↗
PubMed2000

Genetic heterogeneity in three Chinese children with Fukuyama congenital muscular dystrophy.

Three Chinese patients, two boys and one girl, were afflicted with the typical clinical, myopathological and neuroradiological findings of Fukuyama congenital muscular dystrophy (FCMD). Polymorphism analysis of our patients did not reveal the founder haplotype (138-192-147-183 in D9S2105-D9S2170-D9S2171-D9S2107) of Japanese FCMD, even though one patient was descended from Japanese ancestry. Full mutational analysis of the fukutin gene revealed that there is neither 3 kb insertion nor point mutation. These findings suggest genetic heterogeneity between Chinese and Japanese FCMD patients.

Child↗
PubMed2000

Anatomy of SUV. Standardized uptake value.

Standardized uptake value (SUV) for [F-18]fluorodeoxyglucose (FDG) studies that is commonly used to differentiate malignant from benign tumors and to assess the efficacy of therapy is reviewed as a simplified calculation of the more general modeling approach. Based on such a basis, the merits and limitations of the SUV approach is examined with reference to literature reports on tumor uptake of FDG. Results indicate the complexity and large variation of glucose uptake mechanism in tumors. Consistently performed procedures and more basic studies are needed to improve the utility of FDG SUV.

Biological Transport↗
PubMed2000

A study on pruritus after parathyroidectomy for secondary hyperparathyroidism.

BACKGROUND: The effective therapy for uremic pruritus remains a clinical challenge, and the factors affecting the pruritus before and after parathyroidectomy have not been defined. STUDY DESIGN: Thirty-seven patients were operated on for secondary hyperparathyroidism. Their ages ranged from 14 to 73 years, and the duration of dialysis from 12 to as long as 168 months. Indications for surgery were skin itch in 22 patients and other reasons in 15 patients. Serum levels of calcium, phosphorus, intact PTH (i-PTH), and alkaline phosphatase were checked at two different intervals-before surgery and 1 week after operation. Immunohistochemical stain of mast cells, antihuman macrophage (CD68), antihuman dendritic reticulum cell (CD35), and i-PTH (IHPTH) were performed on skin specimens. Skin samples were prepared into tissue homogenates and analyzed for concentrations of interleukin-2 (II-2) and tumor necrosis factor-alpha (TNF-alpha). II-2 and TNF-alpha were measured by sandwich enzyme-linked immunosorbent assay. The extent of pruritus was evaluated on a visual analog scale (VAS) ranging from 0 to 10 and a behavior rating scale (BRS) ranging from 0 to 5, at a preoperative stage and 1 week after operation. RESULTS: Serum levels of calcium, phosphorus, the product of calcium and phosphorous (Ca x P), alkaline phosphatase, and i-PTH changed significantly after parathyroidectomy. The VAS decreased from 5.4 +/- 3.2 to 1.8 +/- 1.5 (p < 0.001). Significant improvement of BRS was achieved 1 week after surgery (p < 0.001), and in the followup period. Before surgery, there was no correlation between serum levels of calcium, phosphorus, Ca x P, alkaline phosphatase, i-PTH, number of mast cells, CD68, CD35, and IHPTH, and the scale of itch estimated with either VAS or BRS. The tissue levels of Il-2 and TNF-alpha were not detectable in any of them. We noted that high levels of phosphorus and Ca x P affected the postoperative extent of pruritus. But a linear regression test showed Ca x P was the only factor affecting postoperative itch. CONCLUSIONS: Pruritus in patients with secondary hyperparathyroidism can be reduced by parathyroidectomy. Apparently, high-level Ca x P is the only factor that seems to affect the postoperative extent of pruritus.

Adult↗
PubMed2000

Nigrostriatal reduction of aromatic L-amino acid decarboxylase activity in MPTP-treated squirrel monkeys: in vivo and in vitro investigations.

Aromatic L-amino acid decarboxylase (AAAD) activity was examined in vivo with positron emission tomography (PET) using 6-[18F]fluoro-L-DOPA (FDOPA) in squirrel monkeys lesioned with graded doses of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In vitro biochemical determinations of AAAD activity in caudate, putamen, substantia nigra, and nucleus accumbens were performed in the same animals to establish a direct comparison of in vivo and in vitro measurements. In vivo and in vitro AAAD activities in caudate/ putamen were substantially reduced in animals treated with the highest dose of MPTP (2.0 mg/kg). The percent change in the striatal FDOPA uptake (K(i)) and decarboxylation rate constant (k3) values resulting from MPTP treatment showed highly significant correlations with in vitro-determined AAAD activities. However, decarboxylase rates within individual animals presented as approximately 10-fold difference between in vivo and in vitro values. Lower in vivo k3 measurements may be attributed to several possibilities, including transport restrictions limiting substrate availability to AAAD within the neuron. In addition, reductions in AAAD activity in the substantia nigra did not parallel reductions in AAAD activity within the striatum, supporting the notion of a nonlinear relationship between nigrostriatal cell degeneration and terminal losses. This work further explores the role of AAAD in Parkinson's disease, a more important factor than previously thought.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2000

Dissociation of cerebral glucose metabolism and level of consciousness during the period of metabolic depression following human traumatic brain injury.

Utilizing [18F]fluorodeoxyglucose positron emission tomography (FDG-PET), we studied the correlation between CMRglc and the level of consciousness within the first month following human traumatic brain injury. Forty-three FDG-PET scans obtained on 42 mild to severely head-injured patients were quantitatively analyzed for the determination of regional cerebral metabolic rate of glucose (CMRglc). Reduction of cerebral glucose utilization, defined as a CMRglc of < or =4.9 mg/100 g/min, was present regionally in 88% of the studies. The prevalence of global cortical CMRglc reduction was higher in severely head-injured patients (86% versus 67% mild-moderate), although the absolute magnitude was similar across the injury severity spectrum (mean CMRglc 3.9 +/- 0.6 mg/100 g/min). The level of consciousness, as measured by the Glasgow Coma Scale, correlated poorly with the global cortical CMRglc value (r = 0.08; p = 0.63). With regards to severity of head injury, this correlation was worst for the severely injured (r = -0.11; p = 0.58) and better for the mildly injured patients (r = 0.50; p = 0.07). In most cases, intraparenchymal hemorrhagic lesions were associated with either focal CMRglc reduction or elevation. It is concluded that the etiologies of CMRglc reduction are likely multifactorial given the complex nature of traumatic brain injury and that the reduction of CMRglc represents a fundamental pathobiologic state following head injury that is not tightly coupled to level of consciousness.

Adult↗
PubMed2000

A nonerythroid isoform of protein 4.1R interacts with components of the contractile apparatus in skeletal myofibers.

The approximately 80-kDa erythroid 4.1R protein is a major component of the erythrocyte cytoskeleton, where it links transmembrane proteins to the underlying spectrin/actin complexes. A diverse collection of 4.1R isoforms has been described in nonerythroid cells, ranging from approximately 30 to approximately 210 kDa. In the current study, we identified the number and primary structure of 4.1R isoforms expressed in adult skeletal muscle and characterized the localization patterns of 4.1R message and protein. Skeletal muscle 4.1R appears to originate solely from the upstream translation initiation codon (AUG-1) residing in exon 2'. Combinations of alternatively spliced downstream exons generate an array of distinct 4.1R spliceoforms. Two major isoform classes of approximately 105/110 and approximately 135 kDa are present in muscle homogenates. 4.1R transcripts are distributed in highly ordered signal stripes, whereas 4.1R protein(s) decorate the sarcoplasm in transverse striations that are in register with A-bands. An approximately 105/110-kDa 4.1R isoform appears to occur in vivo in a supramolecular complex with major sarcomeric proteins, including myosin, alpha-actin, and alpha-tropomyosin. In vitro binding assays showed that 4.1R may interact directly with the aforementioned contractile proteins through its 10-kDa domain. All of these observations suggest a topological model whereby 4.1R may play a scaffolding role by anchoring the actomyosin myofilaments and possibly modulating their displacements during contraction/relaxation.

Actins↗
PubMed2000

Striatal kinetic modeling of FDOPA with a cerebellar-derived constraint on the distribution of volume of 30MFD: a PET investigation using non-human primates.

The peripherally born metabolite of FDOPA, 3-O-Methyl-FDOPA (3OMFD), crosses the blood-brain barrier, thus complicating positron emission tomography-FDOPA (PET-FDOPA) data analysis. In previous reports the distribution volume (DV) of 3OMFD was constrained to unity. We have recently shown that the forward transport rate-constant of FDOPA (K(S1)) and the cerebellum-to-plasma ratio (C(b)/C(p)), a measure for the DV of 3OMFD, are functions of plasma large neutral amino acid (LNAA) concentration. Given large interstudy and intersubject differences in plasma LNAA levels, variations in the DV of 3OMFD are significant. In this report, the authors propose a constraint on the DV of 3OMFD that accounts for these variations. Dynamic PET-FDOPA scans were performed on 12 squirrel monkeys and 12 vervet monkeys. Two sets of constraints were employed on the compartmental model--M1 or M2. In M1, the striatal DV of 3OMFD was constrained to unity; in M2, the striatal DV of 3OMFD was constrained to an estimate derived from the cerebellum. Striatal and cerebellar time-activity curves were fitted using FDOPA and 3OMFD plasma input functions. The estimate of K(S1) and that of the compartmental FDOPA uptake-constant (K(i)), both obtained using M2, were adjusted to values corresponding to average LNAA levels. Finally, K(i) was compared with the graphical uptake-constant (PK(j)). With the use of constraint M2, intersubject variability of squirrel monkey k(S3) and K(i) was reduced by 45% and 53%, respectively; and for vervet monkeys, by 54% and 44%, respectively. Intersubject variability of K(1) and K(i) was further reduced after correction for variations in intersubject plasma LNAA levels (for squirrel monkeys, by 67% and 41%; for vervet monkeys, by 40% and 36%, respectively). K(i) correlation to PK(i) was enhanced to identity. Finally, average cerebellar k(C2) estimates were more than 2.5-fold higher than striatal k(S2) estimates (P < 0.0001). In modeling of PET-FDOPA data, it cannot be assumed that the DV of 3OMFD is unity. The cerebellar-derived constraint furnishes a reliable estimate for the DV of 3OMFD. Invoking the constraint and correcting for variations in plasma LNAA significantly reduced interstudy and intersubject variations in parameter estimates.

Animals↗
PubMed2000

Distribution volume of 3-O-methyl-6.

The distribution volume (DV) of 6-[F-18]fluoro-L-DOPA (FDOPA) in the cerebellum recently has been linked using positron emission tomography (PET) to plasma large neutral amino acid (LNAA) concentrations in monkeys. In this article the authors provide additional experimental support for this relation by directly measuring the DV as the steady-state tissue to plasma radioactivity ratio in rats using a labeled LNAA analog 3-O-methyl-6-[F-18]FDOPA (OMFD), a compound that has no known specific enzyme or receptor interactions in brain tissue. The measured DV for OMFD (tissue OMFD concentration/plasma OMFD concentration) was found to be inversely related to plasma LNAA concentrations. The relation (DV = 1.5-0.00094*[LNAA], R--2 = 0.79) resulted in an 8% DV decrease per 100 nmol/mL plasma LNAA increase within the observed range of 330 to 510 nmol/mL. This was similar to recent noninvasive observations with FDOPA PET in vervet monkeys and with 6-[F-18]Fluoro-m-tyrosine PET in squirrel monkeys. The OMFD striatum to cerebellum (Str/Cb) ratio was greater than 1.0 for all measurements, averaging 1.09 +/- 0.04, and was approximately equal to the Str/Cb LNAA ratio of 1.12 +/- 0.05. This current study verifies the variation of DV of OMFD or FDOPA as a function of plasma LNAA concentrations and suggests the possibility of using OMFD for measuring cerebral LNAA noninvasively with PET.

Amino Acids, Neutral↗
PubMed2000

Diagnostic usefulness of telomerase activity in nasopharyngeal carcinoma.

Telomeres are specialized structures at the ends of eukaryotic chromosomes which are composed of simple repetitive G-rich hexameric sequences. Activation of telomerase, a ribonucleoprotein that synthesizes telomeric DNA, is found in most malignant tumors. However, little data is available concerning the correlation between telomerase activity and NPC (nasopharyngeal carcinoma). In this study, telomerase activation was determined using the TRAP (telomerase repeat amplification protocol) assay in 62 nasopharyngeal biopsies (25 NPC, 25 non-malignant nasopharyngeal lymphoid tissues, 12 post-irradiated nasopharyngeal tissues). The results showed that strong telomerase activity was present in both NPC and non-malignant nasopharyngeal biopsies. Post-irradiated nasopharyngeal samples had a significantly lower telomerase activity than NPC and non-malignant nasopharyngeal lymphoid tissues. It is well known that nasopharyngeal tissue is infiltrated by numerous lymphocytes, which might retain telomerase activity. Therefore, the finding that the telomerase activation was lowest in post-irradiated nasopharyngeal tissues is reasonable because of the destruction of activated lymphocytes and NPC by radiation. NPC biopsies with positive lymph node involvement exhibited higher levels of telomerase compared to those without lymph node involvement. Our data indicate a positive association between telomerase activity and tumor potential for lymphatic spreading in limited local tumors. In addition, telomerase activity may be useful as a diagnostic marker in the detection of tumor cells in recurrent NPC, but not in primary NPC.

Adolescent↗
PubMed2000

Head injury in facial impact--a finite element analysis of helmet chin bar performance.

The chin bar of a motorcycle helmet protects the rider from facial and head injuries. To evaluate the protective performance of chin bars against head injuries from facial impacts, an explicit finite element method was used to simulate the Snell Memorial Foundation test and a proposed drop test. The maximum acceleration and Head Injury Criterion (HIC) were employed to assess the impact-absorbing capability of the chin bar. The results showed that the proposed approach should be more practical than the Snell test, and provided more information for improving the chin bar design to protect against head injuries. The shell stiffness was important in determining the protective ability of the chin bar, but a chin bar with only an outer shell and comfort foam offered inadequate protection. An energy-absorbing liner was essential to increase the protective performance of the chin bar and the liner density should be denser than that used in the cranial portion of the helmet. For the chin bar with energy-absorbing liner, a shell design that is less stiff would provide better protection.

Craniocerebral Trauma↗
PubMed2000

Renal dysplasia and situs inversus totalis: an autopsy case report and literature review.

Renal dysplasia has rarely been reported to be associated with situs inversus. Only 4 cases were reported previously with a spectrum of anomalies including bilateral renal dysplasia, situs inversus totalis, and pancreatic and hepatic fibrosis. Recently we encountered another case. A 22-year-old mother, gravida 1 para 0, was in her 23rd week of gestation when she was found to have oligohydramnios. A dead baby was delivered by extraovular induction. On autopsy, Potter's sequences including flattened, low-set ears, receding chin, upturned nose, and club hands and feet were noted. The posterior fontanel was obliterated. Internal examination showed situs inversus totalis, bilateral renal dysplasia, and agenesis of bilateral ureters. There was increased interstitial fibrosis in the pancreas. None of the family members was known to have any renal anomalies. Pinar and Rogers suggested a new syndrome when situs inversus totalis was combined with bilateral renal dysplasia as well as multisystem fibrosis. In our case, 2 major abnormalities, i.e., situs inversus totalis and bilateral renal dysplasia, were present though the increase of interstitial fibrosis within the pancreas was not as significant. This case is likely to be within the spectrum of anomalies mentioned by Pinar and Rogers.

Adult↗
PubMed2000

Laparoscopic cystectomy of a twisted, benign, ovarian teratoma in the first trimester of pregnancy.

Adnexal torsion is an unusual, but serious complication in pregnancy. The treatment is surgical, but this may increase the risk of pregnancy loss in the first trimester. The use of laparoscopic surgery, which is less invasive than traditional laparotomy, has been limited by diagnostic and technical difficulties including determination of ovarian tumor nature and spillage of cyst contents intraoperatively. A 25-year-old woman in her 11th week of pregnancy had acute severe left lower-abdominal pain, which was diagnosed as left ovarian teratoma with torsion. She underwent emergency laparoscopic surgery with unwinding of the twisted fallopian tube and ovary and cystectomy of the teratoma. The patient subsequently delivered a full-term baby, without complications. Accurate ultrasound and cytologic diagnoses along with copious intraoperative warm, normal saline irrigation were likely contributing factors to the successful outcome of this case.

Adult↗