Modulation of baroreflex function by rosiglitazone in prediabetic hyperglycemic rats.

Baroreflex sensitivity (BRS) is abnormal in the prediabetic state. This study was conducted to determine effects of chronic rosiglitazone (RSG), an insulin sensitizer, on BRS in prediabetic hyperglycemic (PDH) rats induced by nicotinamide and streptozotocin. The fasting and postprandial blood glucose levels were 5.6-6.9 and 7.8-11.0 mmol/l, respectively. Rats were treated with RSG or saline for 12 weeks. BRS response to phenylephrine (PE-BRS) or sodium nitroprusside (NP-BRS) was determined by linear regression method. Cardiac sympathetic and parasympathetic influences were determined by autonomic blockades. In the saline-treated PDH rats, PE-BRS was enhanced early at week 4 and became greater at week 12. Abnormalities in NP-BRS and cardiac autonomic influences were found only after week 12. Four weeks of RSG treatment normalized blood glucose levels but not PE-BRS. All altered cardiovascular variables were completely restored by 12 weeks of RSG treatment. The correlation between BRS and blood glucose levels in saline-treated PDH rats was significant at week 12, but no correlation was found in RSG-treated rats. In conclusion, hyperglycemia, even in the prediabetic state, may play a role in BRS abnormalities. RSG treatment early in the prediabetic state may normalize BRS via cardiac autonomic modulation, besides its anti-hyperglycemic action.

Arylamine N-acetyltransferase activity and 2 aminofluorene-DNA adducts formation in rat glial tumor cells.

Arylamine N-acetylation capacity by the N-acetyltransferase (NAT) may be an important causative factor in the initiation of cancer. Arylamine-DNA adducts formation have been correlated with the carcinogenic effect of heterocyclic aromatic amines. NAT activity in rat glial tumor cells was measured by high performance liquid chromatography (HPLC) using 2-aminofluorene (2-AF) and p-aminobenzoic acid (PABA) as substrares. 2-AF-DNA adducts formation in rat glial tumor cells was investigated by gamma-[32p]-dATP and HPLC using 2-aminofluorene as substrates. The activities (Mean +/- SD) of NAT in rat glial cells was 1.08 +/- 0.18 nmol/min/mg protein for the acetylation of 2-aminofluorene (n = 12), and 0.96 +/- 0.16 nmol/min/mg protein for the acetylation of p-aminobenzoic acid (n = 12). 2-AF-DNA adducts formation in rat glial tumor cells with 30 microM and 60 microM AF were 0.48 +/- 0.16 and 0.70 +/- 0.12 pmol/mg DNA, respectively. The results indicate that NAT was present in rat glial tumor cells, activating AF to become a metabolite able to bind covalently with DNA to form 2-AF-DNA.

Use of esophagectomy to treat recurrent hyperplastic tissue obstruction caused by multiple metallic stent insertion for corrosive stricture.

We report a case of a 75-year-old woman who received repeated metallic stent insertion for corrosive esophageal injury. She underwent esophagectomy and gastric tube reconstruction about 3 years after injury because both stents were occluded in turn by overgrowth of granulation tissue. The gross and microscopic changes of the esophagus secondary to prolonged stent insertion are described. In the literature, no reports of similar cases have been recorded. Our limited experience revealed that using metallic stents to treat benign esophageal stricture should be handled very cautiously because of the complications which can commonly occur and are difficult to manage. Repeated stent insertion, although effective for temporarily relieving dysphagia, is ineffective in the long run and can create complications. We suggest that the feasibility of esophagectomy should be evaluated after the improvement of the general condition of the patient.