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Biomedical subjects

C F Chang

Publications and source records attributed to C F Chang.

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

Regulation of plasma gonadotropin II secretion by sex steroids, aromatase inhibitors, and antiestrogens in the protandrous black porgy, Acanthopagrus schlegeli Bleeker.

Plasma gonadotropin II (GTH II) concentrations were significantly higher (approx. 15-20-fold) in estradiol-17beta (E(2)) treated (1.0 microg or 2.5 microg g(-1) body weight) female black porgy from days 4 to 12 compared with the control. E(2) (1 microg g(-1) wt.) had a stronger stimulation on plasma GTH II in early recrudescent phase (low GSI) males (11-fold) than in high GSI and late spermiating males (2.6-fold, P< 0.05). No effect of androgens (testosterone, T; 5alpha-dihydrotestosterone, DHT) on plasma GTH II levels was observed either sex. The levels of plasma GTH II were stimulated in 1,4,6-androstatriene-3,17-dione (ATD, 1 microg g(-1), 2 microg g(-1) body wt.) and fadrozole-treated (1 microg g(-1), 3 microg g(-1) body wt.) groups compared to control. Tamoxifen (1 microg g(-1), 3 microg g(-1) body wt.) but not enclomiphene could stimulate high GTH II levels in plasma. In another experiment of ATD in combination with T, T treatment further attenuated the ATD stimulation of plasma GTH II levels. We concluded that GTH II secretion is positively regulated by an estrogen-specific effect in female and male black porgy. Gonadal stage had significant effects on the responsiveness of GTH II to E(2) stimulation in males. A negative aromatase-dependent feedback control of plasma GTH II levels was also suggested in the protandrous black porgy, Acanthopagrus schlegeli.

Animals↗
PubMed2001

Utilization of agricultural waste corn cob for the preparation of carbon adsorbent.

In the present study, a series of activated carbons were prepared from agricultural waste corn cob by chemical and physical activations with potassium hydroxide (KOH)/potassium carbonate (K2CO3) and carbon dioxide (CO2). The effect of process variables such as impregnation ratio, impregnation time, activation temperature and soaking time of CO2 was studied in order to relate these preparation parameters with the physical properties of final carbon products. The resulting activated carbons were characterized by nitrogen adsorption-desorption isotherms at 77 K. The surface areas and pore volumes of carbons were estimated by the BET equation, the Langmuir equation and the t-plot method. Under the experimental conditions investigated, the main parameters in the activation of corn cob were found to be the impregnation ratio and activation temperature. The soaking time of CO2 is another important variable, which had a strong effect on the pore volume development. The BET surface area and total pore volume were as large as about 2000 m2/g and about 1.0 cm3/g, respectively. This study showed that the activation of agricultural waste corn cob with KOH/K2CO3 and CO2 was suitable for the preparation of large-surface-area activated carbons.

Adsorption↗
PubMed2001

Hepatocellular carcinoma with Pancoast's syndrome as an initial symptom: a case report.

Pancoast's syndrome refers to a condition consisting of Horner's syndrome and arm pain that is most commonly found in patients with a lung tumor of the superior sulcus invading the upper ribs or spine, lower brachial plexus and sympathetic chain. We report a 76-year-old female who had a thoracic inlet mass that presented as Pancoast's syndrome, showing profound pain, numbness and weakness of the left upper limb. Further evaluation revealed an increased level of serum alpha-fetoprotein (24278 ng/ml), cryptogenic liver cirrhosis and primary hepatocellular carcinoma with protruding T3 vertebra metastasis that resulted in Pancoast's syndrome. To our knowledge, it is a rare case and only one case has been reported previously.

Aged↗
PubMed2001

Use of dexamethasone on the prophylaxis of nausea and vomiting after tympanomastoid surgery.

OBJECTIVE: The aim of this study was to evaluate the prophylactic effect of dexamethasone on postoperative nausea and vomiting (PONV) in patients undergoing tympanomastoid surgery. STUDY DESIGN: Eighty patients (n = 40 in each of two groups) undergoing tympanomastoid surgery under general anesthesia were enrolled in this randomized, double-blind, placebo-controlled study. METHODS: After tracheal intubation, group 1 received 10 mg dexamethasone intravenously, whereas group 2 received saline intravenously. Several parameters concerning with the occurrence of PONV were evaluated. RESULTS: We found that dexamethasone reduced the total incidence of nausea and vomiting by 45%, with a 95% confidence interval of 26% to 64% (P <.001). Furthermore, dexamethasone reduced the incidence of vomiting episodes >4 times and the incidence of patients requiring rescue antiemetics (P <.05). CONCLUSION: Dexamethasone at a dosage of 10 mg administered intravenously is effective in preventing PONV in patients undergoing tympanomastoid surgery.

Adult↗
PubMed2001

The association of smoking and the cost of military training.

OBJECTIVE: To determine if premature discharge from the US Air Force was associated with the smoking status of recruits. DESIGN AND SETTING: A total of 29 044 US Air Force personnel recruited from August 1995 to August 1996 were administered baseline behavioural risk assessment surveys during basic military training. They were tracked over a 12 month period to determine those who were prematurely discharged. MAIN OUTCOME MEASURES: Excess training costs as a result of premature discharge. RESULTS: In this 12 month period, 14.0% of those entering the US Air Force were discharged at a one year follow up. In both univariate and multivariate models, the best single predictor of early discharge was smoking status. Overall, 11.8% of non-smokers versus 19.4% of smokers were prematurely discharged (relative risk 1.795). CONCLUSIONS: Using US Department of Defense data on the cost of military training, recruits who smoke in the US Air Force are associated with $18 million per year in excess training costs. Applied to all service branches, smoking status, which represents a constellation of underlying behaviours and attitudes that can contribute to early discharge, is associated with over $130 million per year in excess training costs.

Adult↗
PubMed2001

Methamphetamine potentiates ischemia/reperfusion insults after transient middle cerebral artery ligation.

BACKGROUND AND PURPOSE: Previous studies have indicated that both methamphetamine (MA) and ischemia/reperfusion injuries involve reactive oxygen species formation and activation of apoptotic mechanism. That MA could have a synergistic or additive effect with stroke-induced brain damage is possible. The purpose of the present study was to investigate whether administration of MA in vivo would potentiate ischemic brain injury. METHODS: Adult CD-1 mice were pretreated with MA or saline. Each animal later was anesthetized with chloral hydrate and placed in a stereotaxic frame. A subset of animals received intracerebral administration of glial cell line-derived neurotrophic factor (GDNF). The right middle cerebral artery and bilateral carotids were transiently occluded for 45 minutes. Regional cerebral blood flow was measured by laser Doppler. Animals were sacrificed for triphenyltetrazolium chloride staining and p53 mRNA Northern blot assay after 24 hours of reperfusion. Cortical and striatal GDNF levels were assayed by ELISA. RESULTS: We found that pretreatment with MA increased ischemia-induced cerebral infarction. Ischemia or MA alone enhanced p53 mRNA expression. Moreover, MA potentiated expression of p53 mRNA in the ischemic mouse brain. MA pretreatment decreased GDNF levels in ischemic striatum. Intracerebral administration of GDNF before ischemia reduced MA-facilitated infarction. CONCLUSIONS: Our data indicate that MA exacerbates ischemic insults in brain, perhaps through the inhibition of GDNF-mediated pathways and suggest that MA may antagonize endogenous neuroprotective pathways as part of its mechanism of action.

Animals↗
PubMed2001

Bone morphogenetic protein-6 reduces ischemia-induced brain damage in rats.

BACKGROUND AND PURPOSE: Bone morphogenetic protein-6 (BMP6) and its receptors are expressed in adult and fetal brain. Receptors for BMP6 are upregulated in adult brain after injury, leading to the suggestion that BMP6 is involved in the physiological response to neuronal injury. The purpose of this study was to determine whether there was a neuroprotective effect of BMP6 in vivo and in vitro. METHODS: Lactate dehydrogenase and microtubule-associated protein-2 (MAP-2) activities were used to determine the protective effect of BMP6 against H(2)O(2) in primary cortical cultures. The neuroprotective effects of BMP6 were also studied in chloral hydrate-anesthetized rats. BMP6 or vehicle was injected into right cerebral cortex before transient right middle cerebral artery (MCA) ligation. Animals were killed for triphenyl-tetrazolium chloride staining, caspase-3 immunoreactivity and enzymatic assays, and TUNEL assay. A subgroup of animals were used for locomotor behavioral assays. RESULTS: Application of H(2)O(2) increased lactate dehydrogenase activity and decreased the density of MAP-2(+) neurons in culture. Both responses were attenuated by BMP6 pretreatment. Complementary in vivo studies showed that pretreatment with BMP6 increased motor performance and generated less cerebral infarction induced by MCA ligation/reperfusion in rats. Pretreatment with BMP6 did not alter cerebral blood flow or physiological parameters. There was decreased ischemia-induced caspase-3 immunoreactivity, caspase-3 enzymatic activity, and density of TUNEL-positive cells in ischemic cortex in BMP6-treated animals. CONCLUSIONS: BMP6 reduces ischemia/reperfusion injury, perhaps by attenuating molecular events underlying apoptosis.

Animals↗
PubMed2001

Experimental induction of chronic borreliosis in adult dogs exposed to Borrelia burgdorferi-infected ticks and treated with dexamethasone.

OBJECTIVE: To develop a method to experimentally induce Borrelia burgdorferi infection in young adult dogs. ANIMALS: 22 healthy Beagles. PROCEDURE: All dogs were verified to be free of borreliosis. Twenty 6-month-old dogs were exposed to Borrelia burgdorferi-infected adult ticks and treated with dexamethasone for 5 consecutive days. Two dogs not exposed to ticks were treated with dexamethasone and served as negative-control dogs. Clinical signs, results of microbial culture and polymerase chain reaction (PCR) testing, immunologic responses, and gross and histologic lesions were evaluated 9 months after tick exposure. RESULTS: Predominant clinical signs were episodic pyrexia and lameness in 12 of 20 dogs. Infection with B burgdorferi was detected in microbial cultures of skin biopsy specimens and various tissues obtained during necropsy in 19 of 20 dogs and in all 20 dogs by use of a PCR assay. All 20 exposed dogs seroconverted and developed chronic nonsuppurative arthritis. Three dogs also developed mild focal meningitis, 1 dog developed mild focal encephalitis, and 18 dogs developed perineuritis or rare neuritis. Control dogs were seronegative, had negative results for microbial culture and PCR testing, and did not develop lesions. CONCLUSIONS AND CLINICAL RELEVANCE: Use of this technique successfully induced borreliosis in young dogs. Dogs with experimentally induced borreliosis may be useful in evaluating vaccines, chemotherapeutic agents, and the pathogenesis of borreliosis-induced arthritis.

Animals↗
PubMed2001

A critical review of the arguments for insurance coverage for smoking-cessation therapies.

This article elucidates the reasons most insurance companies do not cover smoking-cessation therapies despite their obvious benefits. It critically reviews the arguments for and against using a universal mandate as a strategy to increase use of smoking-cessation programs to realize the associated health benefits and cost-savings. While convincing arguments exist to mandate insurance coverage for self-destructive health behaviors, their merit is tempered by several valid counter arguments. For example, insurance coverage for small, routine, and predictable events, such as smoking-cessation treatment, violates the "first principles" of what ought to be covered when considered from the traditional insurance perspective. An insurance solution to risky behaviors may be to make undesirable behaviors more undesirable to individuals by raising premiums rather than to make them less undesirable with subsidies.

Cost Savings↗
PubMed2001

Access to prenatal, delivery, and newborn care among undocumented Hispanics in the Memphis area.

The purpose of this study was to examine the prenatal, delivery, and newborn care received by undocumented Hispanics in the Memphis area. The focus was to sketch a demographic profile of this population, identify barriers encountered in obtaining prenatal, delivery and newborn care, and present a five-year projection of the demand for prenatal care for this population. Participants included 97 undocumented Hispanic women, who either were pregnant or had a baby within the past 12 months, and health care providers. Most women came from Mexico (90.7%). They tended to be young, to have low educational attainment, to be homemakers, to have a high number of members in their households, to be financially supported by their spouses, and to live at or below the poverty line. The average length of time that they had been in the United States and Memphis were 42 and 21 months respectively. With regard to access to health care, undocumented Hispanics who migrated to the Memphis area lacked adequate prenatal and delivery care, and we estimated that the demand for prenatal care in this population will increase over 60% in the next five years.

Adolescent↗
PubMed2000

Localization of the cyclic ADP-ribose-dependent calcium signaling pathway in hepatocyte nucleus.

CD38 is a type II transmembrane glycoprotein found on both hematopoietic and non-hematopoietic cells. It is known for its involvement in the metabolism of cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate, two nucleotides with calcium mobilizing activity independent of inositol trisphosphate. It is generally believed that CD38 is an integral protein with ectoenzymatic activities found mainly on the plasma membrane. Here we show that enzymatically active CD38 is present intracellularly on the nuclear envelope of rat hepatocytes. CD38 isolated from rat liver nuclei possessed both ADP-ribosyl cyclase and NADase activity. Immunofluorescence studies on rat liver cryosections and isolated nuclei localized CD38 to the nuclear envelope of hepatocytes. Subcellular localization via immunoelectron microscopy showed that CD38 is located on the inner nuclear envelope. The isolated nuclei sequestered calcium in an ATP-dependent manner. cADPR elicited a rapid calcium release from the loaded nuclei, which was independent of inositol trisphosphate and was inhibited by 8-amino-cADPR, a specific antagonist of cADPR, and ryanodine. However, nicotinic acid adenine dinucleotide phosphate failed to elicit any calcium release from the nuclear calcium stores. The nuclear localization of CD38 shown in this study suggests a novel role of CD38 in intracellular calcium signaling for non-hematopoietic cells.

ADP-ribosyl Cyclase↗
PubMed2000

Natural and experimental infection of white spot syndrome virus (WSSV) in benthic larvae of mud crab Scylla serrata.

White spot syndrome virus (WSSV), the causative agent of white spot syndrome in shrimp, has a wide host range which extends to crabs, copepods and other arthropods. In this study, benthic larvae of the mud crab Scylla serrata were captured from Taiwan's coastal waters and screened for the presence of WSSV by polymerase chain reaction (PCR) and in situ hybridization. WSSV was detected in around 60% of the larvae, and this prevalence rate remained fairly constant when the captured larvae were subsequently maintained in an aerated system in the laboratory. WSSV-free larvae obtained from a hatchery were challenged by immersion in a WSSV inoculum. Fifteen days after challenge, cumulative mortality in the experimental group reached 43% compared to 20% in the control group. PCR detection of WSSV in both moribund and surviving specimens clearly implicated the virus as the cause of death in most cases. Histological and in situ hybridization data confirmed that WSSV tissue tropism in Scylla serrata crab larvae is similar to that found in shrimp.

Animals↗
PubMed2000

Localization of plasma membrane CD38 is domain specific in rat hepatocyte.

CD38 is a 42- to 45-kDa type II transmembrane glycoprotein with the ability to synthesize cADPR, a metabolite with potent calcium mobilizing properties independent of IP(3). We report here the primary characterization and localization of CD38 in the plasma membrane fraction of rat hepatocyte. Western blot analysis of a partially purified plasma membrane fraction with a panel of polyclonal antibodies against CD38 detected a 42- to 45-kDa protein band which is characteristic of CD38. ADP-ribosyl cyclase activity was found to be present in the plasma membrane fraction, indicating the presence of functionally active CD38. Subfractionation of the plasma membrane to the sinusoidal and bile canalicular membrane fractions showed the presence of ADP-ribosyl cyclase activity in both fractions with the sinusoidal membrane fraction having a 10-fold higher specific activity than the bile canalicular membrane fraction. Immunohistochemical staining with the same panel of polyclonal antibodies showed exclusive differential spatial localization to both the nuclei and sinusoidal domain of the plasma membrane. It is possible that the different spatial distribution of CD38 in the rat hepatocyte might be responsible for its myriad of previously known functional roles.

ADP-ribosyl Cyclase↗
PubMed2000

Hyperbaric oxygen therapy for treatment of postischemic stroke in adult rats.

The efficacy of hyperbaric oxygen (HBO) therapy for treatment of stroke remains to be validated in the laboratory. We report here that adult rats subjected to occlusion of the middle cerebral artery and subsequently exposed to HBO (3 atm, 2 x 90 min at a 24-h intervals; animals terminated shortly after the second treatment) or hyperbaric pressure (HBP; 3 atm, 2 x 90 min at a 24-h interval; animals terminated shortly after the second treatment) immediately after the ischemia or after a 60-min delay generally displayed recovery from motor deficits at 2.5 and 24 h of reperfusion, as well as a reduction in cerebral infarction at 24 h of reperfusion compared to ischemic animals subjected to normal atmospheric pressure. While both HBO and HBP treatments promoted beneficial effects, HBO produced more consistent protection than HBP. Treatment with HBO immediately or 60 min after reperfusion equally produced significant attenuations of cerebral infarction and motor deficits. In contrast, protective effects of HBP treatment against ischemia were noted only when administered immediately after ischemia, which resulted in a significantly reduced infarction volume, but only produced a trend toward decreased behavioral deficits. The present results demonstrate that HBO and, to some extent, HBP reduced ischemic brain damage and behavioral dysfunctions.

Age Factors↗
PubMed2000

Immunomodulation by dietary beta-1, 3-glucan in the brooders of the black tiger shrimp Penaeus monodon.

The present study evaluated the effectiveness of beta-1,3-glucan derived from Schizophyllum commune in enhancing shrimp survival as well as haemocyte phagocytosis and superoxide anion production in brooder Penaeus monodon. Pond-reared P. monodon adults (135 +/- 25 g) stocked in outdoor or indoor tanks were fed either a test diet containing beta-1,3-glucan (2.0 g kg(-1) or a glucan-free control diet for 40 days. Their survival was compared. The brooders reared in indoor tanks were analysed at days 0, 1, 3, 6, 12, 24, 30 and 40 for their haemocyte phagocytic activity and superoxide anion production. The results showed that regardless of indoor or outdoor rearing the survival rate of shrimp fed the glucan diet was significantly higher (P<0.001) than that of the control group. The brooders showed enhanced haemocyte phagocytic activity, cell adhesion and superoxide anion production when glucan was administered in their diets. The immunostimulatory enhancement peaked at day 24 after starting the dietary exposure and subsequently decreased to the pre-feeding level at the end of the 40 days feeding trial.

Adjuvants, Immunologic↗
PubMed2000

Profiles of gonadal development, sex steroids, aromatase activity, and gonadotropin II in the controlled sex change of protandrous black porgy, Acanthopagrus schlegeli Bleeker.

The objectives of the present study were to investigate the effects of oral administration of estradiol-17 beta (E(2)) on the sex steroids and gonadotropin II (GTH II) in plasma, aromatase activity in gonad and brain, and sex change in protandrous black porgy, Acanthopagus schlegeli Bleeker. Two-year-old black porgy were divided into two groups, one fed a control diet and the other a diet mixed with E(2) (4.0 mg/kg feed) for 7 months. Significantly higher GSI was observed in the E(2) group. Fish treated with E(2) showed complete suppression of spermatogenesis and spermiation and induced sex change with vitellogenic oocytes and large primary oocytes. Lower levels of plasma 11-ketotestosterone and higher levels of plasma vitellogenin were shown in the E(2) group. Higher gonadal aromatase activity in concordance with elevated plasma levels of GTH II was observed in the E(2) group. The highest aromatase activity in the forebrain in the control group was observed in January. Higher aromatase activity in forebrain, midbrain, and hindbrain was also detected in the E(2) group than the control group. The change of aromatase activity in brain was more susceptible than that in gonad. The data showed that the increase of plasma GTH II levels and gonadal aromatase activity may be important to the controlled sex change by administration in black porgy.

Animals↗