Search PubMed⌕ Search

Biomedical subjects

S J Wang

Publications and source records attributed to S J Wang.

At least 19 recordsLinked to original sources
PubMed1999

Long-term depression of excitatory synaptic transmission in the rat amygdala.

In view of the fact that both kindling and fear-potentiated startle are expressed by long-term enhancement of synaptic transmission in the amygdala, synaptic plasticity in this area of the brain is of particular importance. Here, we show for the first time that low-frequency stimulation of the lateral nucleus at 1 Hz for 15 min elicited a long-term depression (LTD) in the basolateral amygdala (BLA) neurons. LTD is expressed specifically at the lateral-BLA synapses but not at ventral endopyriform nucleus-BLA synapses. The induction of LTD requires activation of both NMDA and metabotropic glutamate receptors. Loading cells with a Ca(2+) chelator BAPTA or extracellular superfusion with protein phosphatase inhibitors prevents LTD, suggesting that LTD may result from dephosphorylation of AMPA receptors. The same stimulating protocol could not elicit LTD in neurons from kindled animals, whereas neurons from sham-operated or age-matched control rats were able to exhibit LTD. Together, this study characterizes the properties of LTD in the naïve amygdala slices for the first time and demonstrates that epileptogenesis in vivo induces disruption of LTD in the in vitro preparation.

Amygdala↗
PubMed1999

ApoE genotype in relation to AD and cholesterol: a study of 2,326 Chinese adults.

OBJECTIVE: To calculate the frequencies of apolipoprotein E (apoE) alleles in a large Chinese community sample and to compare the serum cholesterol levels of epsilon2, epsilon3, and epsilon4 carriers. BACKGROUND: In comparison with Western populations, a lower frequency of the apoE epsilon4 allele among the Chinese has been proposed as one factor for the lower prevalence of AD found in Chinese populations, but there are insufficient Chinese data on epsilon4 frequency that are based on large community samples. In addition, although Western studies have repeatedly found a lower cholesterol level in epsilon2 carriers and a higher cholesterol level in epsilon4 carriers in comparison with epsilon3 homozygotes, two Chinese studies have yielded inconsistent findings between them. METHODS: During the incidence phase of an epidemiologic survey of several neurologic disorders in a Chinese community, the authors took blood samples from 2,326 participants to determine the apoE genotypes and to measure cholesterol levels. RESULTS: The allelic frequencies of epsilon2, epsilon3, and epsilon4 were 11.8%, 76.4%, and 11.8% among 17 AD patients, and 7.8%, 84.1%, and 8.1% for the entire sample. The mean cholesterol level of the epsilon2 carriers was significantly lower, and that of the epsilon4 carriers significantly higher, than that of the epsilon3 homozygotes. CONCLUSIONS: The obtained epsilon4 rate of 8.1% is lower than most of the Western findings, and this may account in part for the lower prevalence of AD found among the Chinese. The associations between the apoE genotype and serum cholesterol level are similar between Chinese and white populations.

Aged↗
PubMed1999

Colour doppler imaging for diagnosis of intracranial hypotension.

BACKGROUND: Measurement of CSF pressure is the only known way to confirm the diagnosis of intracranial hypotension. We aimed to assess colour doppler flow imaging (CDFI) for measurement of blood flow of the superior ophthalmic vein for the diagnosis of intracranial hypotension. METHODS: We enrolled 25 consecutive patients with orthostatic headache who had clinical features of intracranial hypotension. We defined low-pressure headache as cerebrospinal-fluid pressure below 60 mm H2O. We used CDFI to measure the diameter and maximum flow velocity of the superior ophthalmic vein in all patients. Magnetic resonance imaging of the brain and lumbar puncture with measurement of cerebrospinal-fluid pressure within 24 h were also done after sonographic examination. The control group comprised 13 healthy individuals of a similar age; in addition, those patients who had orthostatic headache without low pressure served as a control group for the patients. FINDINGS: Of the 25 patients recruited for this study, 13 satisfied the criteria for low-pressure headache. The remaining 12 patients with normal cerebrospinal-fluid pressure had transformed migraine (five patients) or chronic tension-type headache (seven patients), and therefore served as the control group for the patients. The mean diameter of the superior ophthalmic vein was substantially larger in the patients with intracranial hypotension (3.9 [SD 0.2] mm) than in the healthy controls (2.6 [0.4] mm) and the controls from the patients' group (2.7 [0.2] mm) (p<0.0001). The mean maximum flow velocity was significantly higher in the intracranial-hypotension group (17.0 [SD 3.4] cm/s) than in the healthy controls (7.9 [1.1] cm/s) and the other patients (7.3 [1.7] cm/s) (p<0.0001). Seven patients with intracranial hypotension were reassessed after treatment with epidural blood patch. After this treatment the clinical symptoms were relieved and there was a striking reversal of the superior ophthalmic vein flow. INTERPRETATION: CDFI to measure blood flow of the superior ophthalmic vein provides a practical, simple, and non-invasive diagnostic method for suspected intracranial hypotension.

Adult↗
PubMed1999

Human very-long-chain acyl-CoA synthetase: cloning, topography, and relevance to branched-chain fatty acid metabolism.

Very-long-chain acyl-CoA synthetases (VLCS) activate very-long-chain fatty acids (VLCFA) containing 22 or more carbons to their CoA derivatives. We cloned the human ortholog (hVLCS) of the gene encoding the rat liver enzyme (rVLCS). Both hVLCS and rVLCS contain 620 amino acids, are expressed primarily in liver and kidney, and have a potential peroxisome targeting signal 1 (-LKL) at their carboxy termini. When expressed in COS-1 cells, hVLCS activated the VLCFA lignoceric acid (C24:0), a long-chain fatty acid (C16:0), and two branched-chain fatty acids, phytanic acid and pristanic acid. Immunofluorescence and immunoblot studies localized hVLCS to both peroxisomes and endoplasmic reticulum. In peroxisomes of HepG2 cells, hVLCS was topographically oriented facing the matrix and not the cytoplasm. This orientation, coupled with the observation that hVLCS activates branched-chain fatty acids, suggests that hVLCS could play a role in the intraperoxisomal reactivation of pristanic acid produced via alpha-oxidation of phytanic acid.

Amino Acid Sequence↗
PubMed1999

Ossification of the posterior longitudinal ligament of the spine. A case-control risk factor study.

STUDY DESIGN: A case-control study. OBJECTIVES: To determine the risk factors for ossification of the posterior longitudinal ligament (OPLL) of the spine. SUMMARY OF BACKGROUND DATA: Previous epidemiologic studies conducted in Japan showed consuming vegetable protein and salt was a risk factor for OPLL. Dietary habits of the Taiwanese and Japanese people are similar. Whether the similar dietary habits play an important role in the high prevalence of OPLL in Taiwan was of interest. METHODS: A case-control study was conducted in a tertiary teaching hospital. The study included 98 consecutive cervical spine patients with OPLL, with 98 age-matched patients with cervical spondylosis serving as control subjects. Radiologic examinations, clinical interviews, physical examinations, and risk factor questionnaires were administered to all the participants. RESULTS: Compared with incidence in the control patients, the frequency of the ossification of the anterior longitudinal ligaments was significantly higher in OPLL patients with OPLL (31% vs. 19%; P = 0.049), but there was no difference in incidence of ossification of the ligamentum flavum (13.3% vs. 16.3%; P = 0.546). More OPLL patients preferred a high-salt diet (OPLL/CS, no:somewhat:yes = 23/38:18/25:57/35;, X2 for trend = 6.3; P = 0.001) and pickled foods (OPLL/CS, no:somewhat:yes = 39/56:11/11:48/31; X2 for trend = 6.7; P = 0.0099). Fewer patients with OPLL consumed meat daily (63% vs. 79%; P = 0.018). High-salt diet (odds ratio = 2.62) and daily meat intake (odds ratio = 0.39) showed persistent association with OPLL in a multivariate logistic regression. CONCLUSIONS: The similar dietary habits, particularly a high-salt and low meat intakes, may partially explain the high prevalence of OPLL in Taiwan and Japan. Modifying dietary habits may help prevent this disease, especially in those high-risk populations.

Aged↗
PubMed1999

Cross-modulation of synaptic plasticity by beta-adrenergic and 5-HT1A receptors in the rat basolateral amygdala.

Neurotransmitter receptors are often colocalized in a neuron with other receptors, and activation of one receptor can either amplify or antagonize the response to a colocalized receptor. The aim of this study was to investigate the cross-regulation of synaptic transmission by beta-adrenergic and serotonin 1A (5-HT1A) receptors and to elucidate their underlying mechanisms. Stimulation of presynaptic beta-adrenergic receptors with isoproterenol (Iso) in the basolateral amygdala resulted in a long-lasting increase in synaptic transmission. This effect was mimicked by forskolin, an activator for adenylyl cyclase and a cAMP analog. In addition, the effect of forskolin was blocked by catalytic and regulatory site antagonists for cAMP-dependent protein kinase (PKA), indicating a PKA-mediated mechanism. Application of 5-HT depressed the synaptic transmission and blocked Iso- and forskolin-induced potentiation. The effect of 5-HT was mimicked by the selective 5-HT1A agonist 8-hydroxy-dipropylaminotetralin and was blocked by the selective 5-HT1A antagonist 1-(2-methoxyphenyl)-4[4-(2-phthalimido)butyl]piperazine, indicating its mediation by 5-HT1A receptors. To determine the locus of interaction, Sp-cAMPS, a membrane-permeable activator of PKA, was applied, and the potentiation produced by Sp-cAMPS was completely blocked in slices pretreated with 5-HT. These results suggest that the interaction between the intracellular signaling pathways activated by 5-HT1A and beta-adrenergic receptors occurs at a step downstream from cAMP production.

Adrenergic beta-Agonists↗
PubMed1999

Human liver-specific very-long-chain acyl-coenzyme A synthetase: cDNA cloning and characterization of a second enzymatically active protein.

Activation of fatty acids, catalyzed by acyl-coenzyme A (acyl-CoA) synthetases, is required for their subsequent metabolism. Peroxisomes and microsomes contain very-long-chain acyl-CoA synthetases (VLCSs) capable of activating fatty acids with a chain length of 22 or more carbons. Decreased peroxisomal VLCS activity is, in part, responsible for the biochemical pathology in X-linked adrenoleukodystrophy (X-ALD), illustrating the importance of VLCSs in cellular fatty acid homeostasis. We previously cloned two human genes encoding proteins homologous to rat peroxisomal VLCS; one (hVLCS) is the human ortholog to the rat VLCS gene and another (hVLCS-H1) encodes a related heart-specific protein. Here, we report the cloning of a third gene (hVLCS-H2) and characterization of its protein product. The hVLCS-H2 gene is located on human chromosome 19 and encodes a 690-amino-acid protein. The amino acid sequence of hVLCS-H2 is 44-45% identical and 67-69% similar to those of both hVLCS and hVLCS-H1. COS-1 cells transiently overexpressing hVLCS-H2 activated the very-long-chain fatty acid lignocerate (C24:0) at a rate >1.5-fold higher than that of nontransfected cells (P < 0.002). The hVLCS-H2-dependent activation of long- and branched-chain fatty acids following transient transfection was less striking. However, hVLCS-H2-dependent acyl-CoA synthetase activity with long- and very-long-chain fatty acid substrates was detected in COS-1 cells stably expressing hVLCS-H2. For all substrates tested (C18:0, C20:0, C24:0, C26:0), the hVLCS-H2 catalyzed activity was significantly increased (P < 0.01 to P < 0.0001). By both Northern analysis and reverse transcription polymerase chain reaction, hVLCS-H2 is expressed primarily in liver. Indirect immunofluorescence of COS-1 cells or human hepatoma-derived HepG2 cells expressing epitope-tagged hVLCS-H2 revealed that the protein was associated with the endoplasmic reticulum but not with peroxisomes. Thus, the primary role of hVLCS-H2 is likely to be in fatty acid elongation or complex lipid synthesis rather than in degradation.

Amino Acid Sequence↗
PubMed1999

Prevalence of paraesophageal varices and gastric varices in patients achieving variceal obliteration by banding ligation and by injection sclerotherapy.

BACKGROUND: The impact of banding ligation and injection sclerotherapy on paraesophageal varices and gastric varices has received scarce attention. We conducted a study using endoscopic ultrasound (EUS) to visualize paraesophageal varices and gastric varices in patients who underwent sclerotherapy and banding ligation. METHODS: Patients with esophageal variceal bleeding whose varices were obliterated by ligation (44 patients) and by sclerotherapy (35 patients) were enrolled. EUS was used to compare the prevalences of paraesophageal varices and gastric varices between the treatment groups. The correlation between paraesophageal varices and esophageal variceal recurrence and recurrent bleeding was assessed. RESULTS: The prevalence of paraesophageal varices was 86% in the ligation group compared with 51% in the sclerotherapy group (p = 0.002). The prevalence of gastric varices was slightly higher in the ligation group than in the sclerotherapy group (43% vs. 26%, p = 0.18). Esophageal varices recurred in 70% of the ligation group and 43% of the sclerotherapy group (p = 0.04). Patients in both groups with more severe paraesophageal varices had a significantly higher rate of variceal recurrence (p = 0.002 in ligation group and p = 0.001 in sclerotherapy group). Bleeding recurred in 6 patients in the ligation group and 4 patients in the sclerotherapy group. All patients with recurrent bleeding had paraesophageal varices. The rate of recurrent bleeding was significantly higher in patients with paraesophageal varices (p < 0.0001). CONCLUSIONS: EUS was helpful in the imaging of paraesophageal and gastric varices after sclerotherapy or banding ligation. Paraesophageal varices were more frequently noted in patients undergoing ligation. The presence of paraesophageal varices may predict the recurrence of esophageal varices and recurrent bleeding.

Endosonography↗
PubMed1999

Effect of reaction conditions on preparations of rhenium-188 hydroxyethylidene diphosphonate complexes.

Rhenium-186 (Re-186) hydroxyethylidene diphosphonate (HEDP) has been shown to localize in metastatic foci within bone in a manner similar to Tc-99m bone-seeking agents. Usually, in the preparation of diagnostic Tc-99m radiopharmaceuticals, the concentration of Tc is at trace level (10(-8) M). However, large amounts of carrier are included in the preparation of Re-186 radiopharmaceuticals (10(-4) M), which may significantly affect the preparation of Re-HEDP. In this study, Re-188 was used as an Re tracer. The effects of pH and concentrations of Re carrier on the preparation of Re-HEDP were investigated. Re-188-Sn-HEDP was prepared by reconstitution of a kit of lyophilized HEDP mixture, and tin chloride with a radioactive solution of perrhenate in saline. The total concentration of Re present in this work ranged from 10(-8) to 10(-3) M. The results showed that high labeling efficiency was obtained for each preparation. Although the chemical behaviors of the Re-188 HEDP complexes, with and without carrier, were similar, the biodistribution patterns of carrier free Re-188 HEDP in rats were found to differ from the biodistribution patterns of carrier-added Re-188 HEDP.

Animals↗
PubMed1999

Open bedside tracheotomy in the intensive care unit.

OBJECTIVE: To demonstrate that open bedside tracheotomy is an efficient, safe, and cost-effective procedure. STUDY DESIGN: Retrospective review of more than 200 open bedside tracheotomies performed at UCLA Medical Center, Harbor-UCLA Medical Center, and West Los Angeles VA Medical Center from 1995 to 1998. METHODS: The only personnel required for the procedure were an attending or senior resident and a junior resident or intern, as well as the respiratory therapist to withdraw the endotracheal tube. No anesthetist or scrub nurse was present for any of the procedures. The procedure took an average of 15 to 25 minutes. Patients were followed for 30 days after surgery to determine the incidence of complications. RESULTS: The incidence of major complications related to the procedure, including hemorrhage and myocardial infarction, was less than 1%. The incidence of minor complications, including moderate bleeding at the tracheotomy site, was 4%. Overall mortality within 30 days was 8%, but was not related to the tracheotomy for any patients in this series. The charge for the procedure was $233 for the tracheotomy tube supplies and instruments. This cost compares favorably with an average charge of more than $3000 for the procedure in the operating room and about $1000 for a percutaneous tracheotomy kit. CONCLUSION: Review of our experience demonstrates that open bedside tracheotomies can be performed more efficiently and economically than operating room tracheotomies. The safety of this procedure is comparable to percutaneous tracheotomy but at a decreased cost.

Adolescent↗
PubMed1999

Radiotherapy followed by neck dissection for small head and neck cancers with advanced cervical metastases.

Patients with small or occult primary carcinomas of the head and neck with advanced cervical metastases present a difficult problem for the otolaryngologist. A retrospective review was performed of patients who presented to UCLA Medical Center between January 1986 and June 1996 with small or occult primary tumors of the head and neck with advanced cervical metastases. The treatment algorithm consisted of initial radiotherapy to the primary site and the neck, followed in 6 to 8 weeks with endoscopy and biopsy of the primary tumor site. As long as the repeat biopsy of the primary tumor site was negative by frozen section, an immediate neck dissection was performed, even if no residual neck disease was present. Almost 40% of patients with no clinical evidence of neck disease following radiotherapy had evidence of metastatic cancer on histopathologic examination. While some would consider a watchful waiting policy when there is no clinically detectable neck disease following radiotherapy, we believe it is preferable to perform immediate surgery in such patients, in light of the high incidence of microscopic metastatic disease.

Carcinoma, Squamous Cell↗
PubMed1999

Impact of dairy farming on well water nitrate level and soil content of phosphorus and potassium.

The Cornell Teaching and Research Dairy Farm was used to study the historical influence of dairy farming on water quality and soil chemical properties. The farm has milked approximately 360 cows for the past 20 yr and is situated on 526 ha of cropland (390 ha utilized for dairy production) near Harford, New York. Mass nutrient balances (N, P, K) were constructed with historical data from 1979 and 1994 for the 390 ha used for dairy production. The amount of imported N increased more than 40% from 1979 to 1994, although there were year-to-year variations, depending on crop yields. Although nutrient balance (imported minus exported nutrients) as a percentage of imported nutrients on the farm remained relatively unchanged during this period, balance of N increased from 43.1 metric tonnes in 1979 to 66.0 metric tonnes in 1994. However, P and K remained about the same because of the reduced use of fertilizers in the 1990s. During the 15-yr period, total milk production increased more than 40% (2502 to 3604 metric tonnes from 1979 to 1994). Analysis of well water suggested that increasing amount of N balance on the farm resulted in increased well NO3-N concentration. The mean of five wells located in the corn fields increased from 3.3 to 7.0 mg/kg in NO3-N concentration, 70% of the EPA upper limit. Soil P increased from 6.0 to 24.0 (kg/ha) during the same period. Soil K did not change. Mass nutrient balances are important in determining the amount of nutrients remaining on farm. This study suggests N, P, and K balance can be used as an indicator of potential for increased NO3-N concentrations in wells and soil P and K levels, respectively.

Animal Feed↗
PubMed1999

Botulism: heart rate variation, sympathetic skin responses, and plasma norepinephrine.

BACKGROUND: Botulism may involve the autonomic nervous system. METHODS: We assessed the autonomic function of 6 botulism patients with heart rate variations, sympathetic skin responses, and plasma norepinephrine. RESULTS: Two weeks after onset, all the patients had absent sympathetic skin response in the palm and sole. Compared with controls, the heart rate variation of botulism patients was significantly decreased at rest (3.1 +/- 1.2% vs. 20.9 +/- 2.0%, p = 0.0018) and during deep breathing (4.3 +/- 2.3% vs. 29.7 +/- 2.6%, p = 0.0018). The botulism patients had significantly lower plasma norepinephrine levels (supine 29.2 +/- 10.1 pg/ml vs. 257.5 +/- 65.8 pg/ml, p = 0.0018; standing 40.3 +/- 13.1 pg/ml vs. 498.5 +/- 85.6 pg/ml, p = 0.0018). The heart rate variation and sympathetic skin response was greatly improved 6 months after onset. CONCLUSIONS: Heart rate variation, absence of sympathetic skin response, and low plasma norepinephrine are all manifestations of autonomic dysfunction in botulism patients.

Adult↗
PubMed1999

Gastric emptying rate assessment based on the proportion of intra-abdominal radioactivity in the stomach.

UNLABELLED: Using scintigraphic techniques, the rate of gastric emptying is calculated by quantifying the absolute radioactivity within a gastric region of interest (intragastric method) with the time of meal completion considered 100% retention. However, this technique has significant limitations arising from subject movement and radionuclide gamma-ray attenuation, which may render curve fitting difficult, particularly in patients with gastroparesis. In an attempt to minimize these limitations, we have expressed the intragastric content as a percentage of the total abdominal radioactivity (abdominal method) and compared these two methods. METHODS: Forty-five subjects in a sitting position consumed a meal consisting of two fried eggs labeled with 99mTc, two slices of toast and 300 mL 5% glucose water (412 kcal). Data were acquired at a rate of one frame every 5 min from the left anterior oblique view. Using the two methods, the intragastric retention ratios at 30, 60, 90, 120 and 240 min and the 50% emptying time (T50) were obtained from both observation and calculation by power exponential fit. R2, representing goodness of fit of the nonlinear curve fitting, was calculated. RESULTS: There were no differences in the calculated values of T50 between the two methods. Quantitative estimates of T50 by extrapolation of a power exponential fit were feasible in 42 of the 45 subjects when the abdominal method was used, compared with only 29 of the 45 subjects when the intragastric method was used. In the 23 subjects with delayed emptying, quantitative estimates of T50 were feasible in 20 subjects when the abdominal method was used, compared with 7 subjects when the intragastric method was used. Using the abdominal method as opposed to the intragastric method also significantly improved R2. The difference between observed values and estimated values of T50 and intragastric retention ratios at 30, 90 and 120 min was smaller using the abdominal method. CONCLUSION: Scintigraphic measurement of gastric emptying calculated using the proportion of the abdominal radioactivity in the stomach offers substantial advantages over conventional methods, particularly in patients with gastroparesis.

Adult↗