Role of Vitamin D3 on the Activity Patterns of Hepatic Drug Metabolizing Enzymes in Transplantable Murine Lymphoma

Vitamin D₃ D₃) has been found to exert varied pharmacological actions including restriction of cell growth of a number of malignant cell lines in vitro and inhibition of the promotion of chemical carcinogenesis in mouse skin. In an attempt to confirm the efficacy of D₃ as an antineoplastic agent, the present investigation aims at characterizing the importance of D₃ in modulating hepatic drug metabolizing enzymes, namely, cytosolic glutathione S-transferase (GSHT), microsomal UDP glucuronyl transferase (UDPGT), and cytochrome P-450, which have been reported by us in recent literature as significant neoplastic markers in mice bearing Dalton's lymphoma (DL). Results show that D₃ causes a 150% elevation of GSHT activity and the maintenance of normal, near-control UDPGT activity and cytochrome P-450 content, up to almost 30 days following tumor transplantation, along with bringing about a twofold increase in survival of the host mice. In conclusion, we confirm the definite and significant antitumorigenic role of D₃ and its involvement with the discussed hepatic tumor markers in monitoring the processes that lead to cell survival     

Role of β-carotene on the changes in activity patterns and levels of biotransforming enzymes in transplantable murine lymphoma

The differential levels of induction of hepatic microsomal cytochrome P-450 (cyt. P-450), UDP-glucuronyl transferase (UDPGT) and cytosolic glutathione-S-transferase (GST) activities were evaluated over various periods of time, following tumor transplantation in male Swiss albino mice in the presence and absence of β-carotene supplementation in their basal diet (100 mg/kg). An increase in the total hepatic microsomal cytochrome P-450 and UDP-glucuronyl transferase and cytosolic GSH-transferase activities (1.5 to 2 fold) occurred during the later stage of tumor progression (22 ± 2 days onwards). However, β-carotene supplementation throughout the study increased or decreased the random activity trends of the above markers significantly (P < 0.05−< 0.01). Finally, β-carotene supplementation could enhance the survival of the host bearing lymphoma by almost 2-fold (50–60 days) over and above the lymphoma controls (30–35 days).     

Evidence that cyclic AMP phosphodiesterase inhibitors suppress interleukin-2 release from murine splenocytes by interacting with a ‘low-affinity' phosphodiesterase 4 conformer

1. We have investigated the suppressive effects of rolipram, RP 73401 (piclamilast) and other structurally diverse inhibitors of cyclic AMP-specific phosphodiesterase 4 (PDE4) on interleukin (IL)-2 generation from Balb/c mouse splenocytes exposed to the superantigen, Staphylococcocal enterotoxin-A (Staph. A). The purpose was to determine whether their potencies are more closely correlated with inhibition of PDE4 from CTLL cells, against which rolipram displays weak potency (low-affinity PDE4), or displacement of [³H]-(±)-rolipram from its high-affinity binding site (HARBS) in mouse brain cytosol.
2. RP 73401 (IC₅₀ 0.46±0.07 nM, n=4) was a very potent inhibitor of Staph. A-induced IL-2 release from Balb/c mouse splenocytes, being >1100 fold more potent than (±)-rolipram (IC₅₀ 540±67 nM, n=3).
3. A close correlation (r=0.95) was observed between suppression of IL-2 release by PDE inhibitors and inhibition of PDE4. In contrast, little correlation (r=0.39) was observed between suppression of IL-2 release and their affinities for the high-affinity rolipram binding site (HARBS).
4. RP 73401 only inhibited partially (30–40%) Staph. A-induced incorporation of [³H]-thymidine into splenocyte DNA. The PDE3 inhibitor, siguazodan (10 μM), had little or no effect on IL-2 release or DNA synthesis. This concentration of siguazodan did not enhance the inhibitory action of RP 73401 on IL-2 release but potentiated its effect on DNA synthesis, increasing potency and efficacy.
5. Staph. A-induced DNA synthesis was only partially inhibited by anti-IL-2 neutralizing antibody, whereas dexamethazone (100 nM) and cyclosporine A (100 nM) completely blocked the response.
6. RP 73401 (IC₅₀ 6.3±1.9 nM, n=4) was 140 fold more potent than rolipram (IC₅₀ 900±300 nM, n=3) in inhibiting Staph. A-induced [³H]-thymidine incorporation into splenocyte DNA.
7. The results implicate a low-affinity form of PDE4 in the suppression of Staph. A-induced IL-2 release from murine splenocytes by PDE inhibitors. The data also indicate that mitogenic factors other than IL-2, whose elaboration or responses to which are regulated by PDE3 as well as PDE4, contribute to the superantigen-induced DNA synthesis.

     

Production of human alloreactive antibodies by uremic sensitized lymphocytes engrafted in severe combined immunodeficient mice.

BACKGROUND: Numerous studies have documented antibody responses to nominal antigens in human peripheral blood lymphocyte (hu-PBL)-severe combined immunodeficient (SCID) mice engrafted with PBL. We suggest, therefore, that engraftment of SCID mice by allosensitized cells produces alloreactive antibodies (allo-Ab). As such, SCID mice can be used as a model to examine the cellular basis of the sustenance of humoral alloresponses. METHODS: C.B-17 SCID mice were engrafted intraperitoneally with PBL from sensitized uremic patients for 5 weeks and classified into the following: group 1, 8 mice engrafted with unactivated cells (n = 5; n = sensitized patients); group 2, 6 mice engrafted with unactivated PBL (n = 3) followed 2 days later by in vivo activation with interleukin-2 (IL-2) and lipopolysaccharide (LPS); group 3, 11 mice engrafted with cells preactivated in vitro with IL-2 and LPS (n = 6); group 4, 9 mice engrafted with cells preactivated with irradiated allogeneic transformed B cells, IL-2, and LPS (n = 5); group 5, 10 mice engrafted with cells preactivated with IL-2, LPS, and HLA class II allopeptides and adjuvant (n = 6); group 6, 8 control mice engrafted with control cells preactivated with IL-2 and LPS. Two weeks later, each group was rechallenged by the same stimuli. Allo-Ab production was measured by the panel-reactive antibody PRA-STAT ELISA method. Results. Allo-Ab was produced in 54.5% of group 3, 43% of group 4; 80% of group 5, and 0% of groups 1, 2, and 6. The ratio of alloreactive positive wells in the allo-Ab-producing PBL-hu-SCID mice to that present in the respective patient's sera was 82%, 52%, and 87% in groups 3, 4, and 5, respectively. Conclusions. The study demonstrates the feasibility of using the hu-PBL-SCID model to study alloreactive memory B-cell function in humans. Discrete HLA-class allopeptides (group 5) appeared more potent allo-Ab producers than allogeneic cells (group 4).     

Arsenic health risk assessment in drinking water and source apportionment using multivariate statistical techniques in Kohistan region,northern Pakistan

The present study was conducted in Kohistan region, where mafic and ultramafic rocks (Kohistan island arc and Indus suture zone) and metasedimentary rocks (Indian plate) are exposed. Water samples were collected from the springs, streams and Indus river and analyzed for physical parameters, anions, cations and arsenic (As³⁺, As⁵⁺ and arsenic total). The water quality in Kohistan region was evaluated by comparing the physio-chemical parameters with permissible limits set by Pakistan environmental protection agency and world health organization. Most of the studied parameters were found within their respective permissible limits. However in some samples, the iron and arsenic concentrations exceeded their permissible limits. For health risk assessment of arsenic, the average daily dose, hazards quotient (HQ) and cancer risk were calculated by using statistical formulas. The values of HQ were found >1 in the samples collected from Jabba, Dubair, while HQ values were <1 in rest of the samples. This level of contamination should have low chronic risk and medium cancer risk when compared with US EPA guidelines. Furthermore, the inter-dependence of physio-chemical parameters and pollution load was also calculated by using multivariate statistical techniques like one-way ANOVA, correlation analysis, regression analysis, cluster analysis and principle component analysis.