Biomedical subjects

J T Cheng

Publications and source records attributed to J T Cheng.

258 records · Page 15Linked to original sources

PubMedDate not supplied

Mediation of beta-endorphin in exercise-induced improvement in insulin resistance in obese Zucker rats.

BACKGROUND: Aerobic exercise including treadmill running has long been used to successfully treat and/or prevent insulin resistance and type-2 diabetes. Increase of plasma beta-endorphin is observed with exercise. The present study was designed to clarify the role of endogenous beta-endorphin in exercise-induced improvement in insulin resistance. METHODS: We used a moderate exercise program consisting of treadmill running at 20 m/min and 0% grade for 1 h/day, 7 days/week, for 8 weeks. Plasma glucose concentration was assessed by the glucose oxidase method. The enzyme-linked immunosorbent assay was performed to quantify the plasma level of beta-endorphin-like immunoreactivity (BER). The glucose disposal rate (GDR) was measured by the hyperinsulinemic euglycemic clamp technique. Changes of the insulin signaling in isolated soleus muscle were then detected by immunoprecipitation and immunoblotting. RESULTS: An increase of plasma BER in parallel with the reduction of plasma glucose was obtained in exercise-trained obese Zucker rats. Different from a marked reduction in sedentary obese rats, the value of insulin-stimulated GDR obtained from the exercised obese rats was reversed to near that of the sedentary lean group, eight weeks after the last period of exercise. This effect of exercise was inhibited by naloxone or naloxonazine at doses sufficient to block opioid micro-receptors. Signaling-related defects in the soleus muscle of sedentary obese Zucker rats, which impaired glucose transporter subtype 4 (GLUT 4), included decreased phosphorylation of insulin receptor substrate (IRS)-1, as well as an attenuated p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3 kinase) and Akt serine phosphorylation. In contrast, exercise training failed to modify the levels of insulin receptor (IR), IRS-1, and IR tyrosine autophosphorylation in obese Zucker rats. CONCLUSION: Enhanced insulin sensitivity via exercise training might be mediated by endogenous beta-endorphin through an increase of postreceptor insulin signaling related to the IRS-1-associated PI3-kinase step that leads to the enhancement of GLUT 4 translocation and improved glucose disposal in obese Zucker rats.

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PubMedDate not supplied

Decrease in catechol-O-methyltransferase activity in the liver of streptozotocin-induced diabetic rats.

1. The present study compared the activity of catechol- O-methyltransferase (COMT) in the liver and plasma of streptozotocin (STZ)-induced diabetic rats with that in normal rats. The activity of COMT was estimated by the metabolism of noradrenaline to metanephrine (MN), both measured by high-performance liquid chromatography with electrochemical detection. 2. Formation of MN was decreased in the liver of STZ- diabetic rats compared with normal rats. The amount of MN was also decreased in plasma obtained from STZ-diabetic rats. A Michaelis-Menten plot showed a reduction in the maximum velocity and an increase in the Km for COMT in liver samples from STZ-diabetic rats. 3. The role of hyperglycaemia in the lowering of COMT activity was then investigated using phlorizin or insulin at doses sufficient to normalize plasma glucose from STZ-diabetic rats. Both insulin and phlorizin treatment of STZ-diabetic rats for 4 days restored the activity of COMT to that seen in normal rats. Thus, correction of hyperglycaemia in STZ-diabetic rats can reverse the decrease in COMT activity. The activity of COMT is lower in STZ-diabetic rats than in normal rats mainly due to the higher plasma glucose.

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PubMedDate not supplied

Serum pepsinogen I levels in patients with non-ulcer dyspepsia.

In order to understand whether the serum pepsinogen I (PGI) levels of non-ulcer dyspepsia (NUD) patients differed from those of healthy controls and which kinds of factors might influence these levels of the former, serum PGI levels were determined by radio-immunoassay in 120 healthy controls and 361 NUD patients. The mean serum PGI level was significantly lower in NUD patients than in the controls (75.8 +/- 38.2 ng/mL versus 95.9 +/- 39.3 ng/mL; P less than 0.0001); in NUD patients, it was significantly higher in males than in females (79.6 +/- 40.4 ng/mL versus 63.2 +/- 26.4 ng/mL; P less than 0.001). However, corrected serum PGI levels according to the lean body mass disclosed no sex difference. Nevertheless, there was a weak correlation between the ages of patients and serum PGI levels (r = 0.403). The serum PGI levels in blood groups A, B, AB and O did not differ significantly. Smoking might be a decisive factor, for the mean serum PGI level was significantly higher among the smokers than among the non-smokers (86.7 +/- 44.6 ng/mL versus 70.6 +/- 33.7 ng/mL; P less than 0.001). It is concluded that the mean serum PGI level of NUD patients, while affected by sex, age, smoker status and the body size, is lower than that of the healthy controls. Without endoscopy, assay of serum PGI level has no place in the diagnosis of dyspepsia because of the wide overlapping of serum PGI levels between NUD patients and patients with other common gastric lesions.

Age Factors↗

PubMedDate not supplied

Medical treatment of duodenal ulcer: acid inhibition or Helicobacter pylori eradication?

To ascertain whether acid inhibition or Helicobacter pylori (HP) colonization is the decisive factor in the healing of duodenal ulcer, we treated 54 patients with famotidine and carried out long-term follow-up. Helicobacter pylori colonization was found in 70.4% of patients before treatment. There were no differences in the pre-treatment characteristics between patients with HP positive or HP negative ulcers. The 4-week and 8-week healing rates after famotidine treatment were 72.5% and 82.4% respectively. No difference in HP colonization was found between patients with ulcer healed and those with ulcer not healed (78.4% vs 64.3% at 4th week and 77.3% vs 71.4% at 8th week, P greater than 0.05). In patients with ulcer healed at 4th week, the intragastric pH was raised significantly and the antral acute inflammation was less severe than those with ulcer not healed. Ulcer recurrence was found in 76.9% of patients within 1 year, but there was no difference in ulcer recurrence between the patients with positive or negative HP colonization at the time of ulcer healing. Our results suggest that duodenal ulcer healing and recurrence are closely related to acid inhibition rather than to HP colonization.

Duodenal Ulcer↗

PubMedDate not supplied

Markedly increased mesiotemporal lobe metabolism in a case with PLEDs: further evidence that PLEDs are a manifestation of partial status epilepticus.

The pathophysiologic and clinical significance of periodic lateralized epileptiform discharges (PLEDs) is unclear; whether PLEDs represent an ictal condition that should be treated remains uncertain. We performed FDG-positron emission computed tomography (FDG-PET) in a patient with PLEDs at 3 days, 18 days, and 10 weeks after onset. During left temporal PLEDs, the initial scan showed intense hypermetabolism of the left mesiotemporal region. The second scan, performed when PLEDs were resolving, displayed reduced hypermetabolism. The follow-up scan, when PLEDs had resolved, showed left temporal hypometabolism. These findings, together with clinical evidence from the literature, are compatible with the interpretation that PLEDs represent partial status epilepticus (SE); whether vigorous therapy is required to prevent neuronal damage from this focal seizure activity remains uncertain.

Aged↗

PubMedDate not supplied

Cardiovascular effect of skimmianine in rats.

Skimmianine, a general component contained in the plants of Rutaceae, was found to have a selective inhibitory effect on the 5-hydroxytryptamine-induced vasopressor responses of rats. A similar inhibitory action was also observed in the isolated atria. Moreover, skimmianine produced a nonspecific blockade of the cardiovascular functions at higher concentration.

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