Relationship between diurnal rhythm of cell cycle and interferon receptor expression in implanted-tumor cells.

Whether the diurnal rhythm of cell cycle is associated with that of interferon-alpha/beta receptor (IFNAR) expression was investigated in implanted-tumor cells. The expression of IFNAR mRNA significantly increased when the proportion of tumor cells in DNA synthesis (S) phase increased in vitro. A diurnal rhythm was observed for cell cycle distribution in implanted-tumor cells. The specific binding of interferon-alpha to receptor and IFNAR mRNA increased when the proportion of tumor cells in S phase increased in vivo. The time-dependent expression of IFNAR was supported by that of transcription factor level induced by interferon-beta. The present result suggests that the rhythm of IFNAR expression is closely related to that of cell cycle distribution in implanted-tumor cells.

High serum level of procollagen type III amino-terminal peptide contributes to the efficacy of spironolactone and angiotensin-converting enzyme inhibitor therapy on left ventricular hypertrophy in essential hypertensive patients.

We recently demonstrated that spironolactone may have beneficial effects on left ventricular hypertrophy in selected patients with essential hypertension undergoing treatment with an angiotensin-converting enzyme (ACE) inhibitor. To clarify the possible mechanisms by which spironolactone improves cardiac hypertrophy, we investigated the change in serum procollagen type III amino-terminal peptide (PIIINP) in 11 patients with essential hypertension treated with spironolactone and an ACE inhibitor for 24 weeks. Both blood pressure and serum PIIINP levels were significantly decreased by treatment. There was a statistical significant correlation between the changes in LVMI and those in PIIINP. The reduction in PIIINP was significant in patients whose initial serum PIIINP levels were above the normal range. Before treatment, there were no statistically significant correlations between serum PIIINP levels and either LVMI, blood pressure, or plasma aldosterone concentration. Essential hypertensive patients matched in terms of duration of therapy, blood pressure and LVMI and treated with an ACE inhibitor alone showed no change in serum PIIINP levels. In conclusion, the results of the present study demonstrate that patients with essential hypertension and high serum levels of PIIINP are particularly responsive to MR blockade in terms of left ventricular hypertrophy. Moreover, these results suggest that spironolactone limits cardiac collagen turnover in such patients. Larger studies may provide definitive evidence for the involvement of aldosterone in left ventricular hypertrophy in patients with abnormally high PIIINP levels.

Effect of dosing schedule on pharmacokinetics of alpha interferon and anti-alpha interferon neutralizing antibody in mice.

The influences of dosing time and dosing schedule on the plasma alpha interferon (IFN-alpha) concentration and the production of anti-IFN-alpha neutralizing antibodies were investigated in ICR male mice adapted to cycles of 12 h of light and 12 h of dark. In mice pretreated with IFN-alpha for 21 days, the plasma IFN-alpha concentrations were significantly lower than those in control mice (P < 0.01). The clearance of IFN-alpha and its volume of distribution obtained at steady state were significantly higher in the animals with IFN-alpha pretreatment than in the mice without IFN-alpha pretreatment. The area under the concentration-time curve and the mean residence time of IFN-alpha were significantly smaller in IFN-alpha-pretreated animals than in control animals. The plasma IFN-alpha levels (measured 2 h after dosing) were significantly lower in mice treated daily with IFN-alpha, while the anti-IFN-alpha neutralizing antibody levels (measured 24 h after dosing) were significantly increased on days 15 and 21 of treatment. Plasma IFN-alpha levels were significantly decreased in association with the production of anti-IFN-alpha neutralizing antibodies in mice treated with IFN-alpha daily at either 0900 or 2100 h. By contrast, the plasma IFN-alpha levels (measured 2 h after dosing) remained stable in mice treated with IFN-alpha at 0900 h on alternate days, while they were significantly lower after 21 days of treatment in mice treated with IFN-alpha at 2100 h on alternate days. These changes were associated with a significant increase in the levels of anti-IFN-alpha neutralizing antibodies in the latter group. The present findings suggest that an appropriate dosing schedule and/or dosing time for IFN-alpha may reduce the level of production of anti-IFN-alpha neutralizing antibodies in experimental and clinical situations.

[Chronological changes of lacunar infarctions on fluid-attenuated inversion recovery magnetic resonance images].

In 26 patients with lacunar syndromes, emergence of new lacunar infarctions were identified within 13 days from onset by diffusion-weighted magnetic resonance images. The identified lacunar infarctions were repeatedly imaged using fluid-attenuated inversion recovery (FLAIR) sequence up to 600 days from onset. On FLAIR images taken by 23 days from onset, lacunar infarctions showed homogeneous hyperintensity. On the later FLAIR images beyond 25 days from onset they were observed as heterogeneously hyperintense lesions in half of the patients. In the other patients, lacunar infarctions were observed as hypointense areas with a hyperintense rim beyond 41 days from onset, which indicates cystic transformation with surrounding gliosis. These FLAIR images of lacunar infarction differ from those of dilated perivascular space which is observed as an area of simple hypointensity.

Basis for dosing time-dependent changes in the antiviral activity of interferon-alpha in mice.

The influence of dosing time on the pharmacological effect (antiviral activity) of interferon-alpha (IFN-alpha), and the pharmacological and pharmacokinetic mechanisms, were investigated in ICR male mice under a 12-h light/dark cycle (lights on from 7:00 AM to 7:00 PM). 2'-5'Oligoadenylate synthetase activity in plasma at 24 h after IFN-alpha (10 MI.U./kg, i.v.) injection, as an index of antiviral activity, was significantly higher for injections given at 9:00 AM than for injections given at 9:00 PM (P <.05). The uptake of [(3)H]thymidine by lymphocytes after 24-h incubation with IFN-alpha, as an index of lymphocyte-stimulating effect, was significantly higher in cells obtained at 9:00 AM than in the cells obtained at 9:00 PM (P <.01). The number of receptors per cell and the expression of interferon-stimulated gene factor in lymphocytes after 24-h incubation with IFN-alpha were significantly higher in the cells obtained at 9:00 AM than at 9:00 PM (P <.05). A significant dosing time-dependent difference was demonstrated for the pharmacokinetic parameters of IFN-alpha, which showed higher clearance for injections given at 9:00 PM than for those at 9:00 AM (P <.05). The metabolism of IFN-alpha was significantly higher in kidney obtained at 9:00 PM than at 9:00 AM (P <.05). These findings support that choosing the most appropriate time of day for administration of IFN-alpha, associated with the rhythmicity of IFN-alpha receptor function and IFN-alpha pharmacokinetics, may increase the antiviral activity in experimental and clinical situations.

Chronopharmacology of antitumor effect induced by interferon-beta in tumor-bearing mice.

The mechanisms underlying the dosing time-dependent change in the antitumor effect of interferon-beta (IFN-beta) were investigated based on the sensitivity of tumor cells and the pharmacokinetics of the drug. Tumor-bearing mice were housed under standardized light-dark cycle conditions (lights on at 7:00 AM, off at 7:00 PM) with food and water available ad libitum. The antitumor effect of IFN-beta (0.5 MI.U./kg, intratumoral) was more efficient in early light phase than in early dark phase. The higher antitumor effect of IFN-beta was observed when specific binding of IFN receptor and DNA synthesis in tumor cells increased, and the lower effect was observed when these levels decreased. The dosing time-dependent effect of IFN-beta was supported by the time-dependent expression of transcription factor (signal transducers and activators of transcription 1) and cell proliferation inhibitor (p21 wild-type p53-activated fragment 1) protein induced by IFN-beta. There was a significant dosing time-dependent change in IFN-beta concentration in tumor, with a higher level in early light phase and a lower level in early dark phase. The dosing time-dependent change of IFN-beta concentration in tumor was associated with that of IFN-beta-induced antitumor effect. These results suggest that by choosing the most suitable dosing time for IFN-beta, the efficacy of the drug can be increased in certain experimental and clinical situations.

Evidence that gender difference affects peritoneal dialysis capacity in continuous ambulatory peritoneal dialysis patients.

The progression of renal disease is reported to be more rapid in male patients than in premenopausal females. However, few studies compare the difference in dialysis therapy between males and females. We compared the efficacy of peritoneal dialysis capacity, using measurements of retention volume and pelvic cavity by helical section of computed tomography (CT) in 6 male and 6 female patients. The patients did not differ significantly in age (males: 54 +/- 3 years; female: 56 +/- 4 years). Males were heavier than females (p < 0.05). Retention volume in the visceral cavity was significantly larger in males (1787 +/- 43 mL) than in females (1580 +/- 59 mL) (p < 0.05). Peritoneal dialysis capacity was evaluated by peritoneal equilibration test (PET). Although no significant differences were observed in the PET data, when the PET results at 4 hours were divided by body weight in kilograms, a significant difference between males and females was seen (p < 0.05). There was a mild, but not significant, correlation between the volume of the pelvis as measured by helical CT and the PET data per kilogram body weight (p = 0.07). These results suggest that gender differences in peritoneal dialysis capacity relate partially to the difference in pelvic cavity volume.