The changes in various hydroxyproline fractions in aortic tissue of rabbits are closely related to the progression of atherosclerosis.

BACKGROUND: The most important function of collagen and elastin is to induce several mechanical parameters which are known to play a dominant role in governing mechanical properties of the blood vessels. The aortic tissue of rabbit is one of the important sources of collagen and elastin. The effects of high fat diet (HFD) on the hydroxyproline (Hyp) fractions in serum and aortic tissues of rabbits and collagen content in the aortic tissues of rabbits have not been documented before. The present study was undertaken to investigate the changes in Hyp fractions in serum and aortic tissues of rabbits and collagen content in the aortic tissues of rabbits during the progression of atherosclerosis. The atherosclerotic model used in this study was the New Zealand white rabbit (male; 12 weeks old). Twenty five rabbits were individually caged, and divided into control group (NOR; n = 10) and HFD group (CHO; n = 15). The control group was fed (100 g/day) of normal (NOR) diet for a period of 15 weeks. The HFD group was fed normal diet supplemented with 1.0% cholesterol plus 1.0% olive oil (100 g/day) for the same period of time. RESULTS: We found that the TC, LDLC, and TG (mg/dl) were significantly (p < 0.001) increased in HFD rabbits compared with control rabbits with percentage normalized changes of 1198%, 1591%, and 710%, respectively. The peptide-bound Hyp in the serum was significantly (P < 0.05) increased in HFD rabbits compared with control rabbits with percentage normalized change of 517% while it significantly (P < 0.01) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 65%. The protein-bound Hyp in the serum was significantly (P < 0.01) increased in HFD rabbits compared with control rabbits with percentage normalized change of 100%; the protein-bound Hyp in the aortic tissues of control rabbits was 235.30 +/- 55.14 (Mean +/- SD) while it was not detectable (ND) in HFD rabbits. Total serum Hyp showed no significant (P < 0.05) change in HFD rabbits compared with control rabbits while it was significantly (P < 0.05) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 73%. The total collagen was significantly (p < 0.01) decreased in aortic tissues of HFD rabbits compared with control rabbits with percentage normalized change of 73% which was supported by histological study. CONCLUSIONS: These results suggest that percentage decrease in various Hyp fractions in aortic tissue of HFD rabbits are closely related to percentage decrease of collagen content in aortic tissues of HFD rabbits. These results also suggest that it may be possible to use the changes in various Hyp fractions in aortic tissues of rabbits as an important risk factor during the progression of atherosclerosis.

Oral theophylline changes renal carnitine palmitoyltransferase activity in rats.

BACKGROUND: Carnitine plays a critical role in lipid metabolism. Carnitine deficiency may adversely affect the oxidation of fatty acids and further aggravate abnormal lipid metabolism. Our objective was to investigate the effect of theophylline on the activity of carnitine palmitoyltransferase (CPT) in renal tissues of rats for 5-week-interval treatments. METHODS: The study was a randomized, controlled animal study. Theophylline was given at 100 mg/kg body weight (b.w.)/day and effects were monitored after a treatment period of between 1 and 5 weeks. RESULTS: Theophylline treatment caused a significant increase in renal CPT activity as compared to either control or placebo groups. Moreover, the results showed positive correlations between the renal concentration of long-chain acylcarnitine (LC), activity of CPT, urinary excretion of acylcarnitine (AC), and plasma concentration of LC (p <0.01), respectively. CONCLUSIONS: The observed changes in activity of renal CPT might be due to the result from theophylline-enhanced mobilization of lipid from adipose tissues that consequently stimulated an increased carnitine transport into the renal tissues to form palmitoylcarnitine groups for subsequent beta-oxidation inside the mitochondria. Thus, these accumulations of palmitoylcarnitine groups in mitochondria may increase the catalytic action of CPT.

Effect of beta-arteether treatment on erythrocytic methemoglobin reductase system in Plasmodium yoelii nigeriensis infected mice.

BACKGROUND: The methemoglobin reductase system plays a vital role in maintaining the equilibrium between hemoglobin (Hb) and methemoglobin (MetHb) in blood. Exposure of red blood cells to an oxidative stress (pathological/physiological) may cause impairment in this equilibrium. OBJECTIVE: The status of MetHb and the related reductase system was studied during Plasmodium yoelii nigeriensis (P. y. nigeriensis) infection and beta-arteether treatment in mice. METHODS: Mice were divided into four groups. Normal group, normal mice treated with beta-arteether, P. y. nigeriensis infected mice and P. y. nigeriensis infected mice treated with beta-arteether. RESULTS: The present investigation revealed a marked decrease in the activity of MetHb reductase, with concomitant rise in MetHb levels during P. y. nigeriensis infection in mice erythrocytes (P < 0.001) as compared to normal mice. However, the activities of the associated enzymes viz., lactate dehydrogenase, glucose 6-phosphate dehydrogenase and glutathione reductase were found to be increased with progressive rise in parasitemia. beta-Arteether treatment (12.5 mg/kg body weight) of infected mice (parasitemia 20-25%) from day 5 of post infection resulted in complete clearance of parasitemia on day 7 of post infection, which was accompanied by restoration of all the altered above mentioned indices to near normal levels as compared to infected mice (P < 0.001). CONCLUSION: These results suggest that there is a marked impairment of methemoglobin and methemoglobin reductase system during P. y. nigeriensis infection in mice. beta-Arteether treatment of infected mice resulted in complete clearance of parasitemia which also caused the restoration of methemoglobin and methemoglobin reductase system to near normal levels.