Histological effects of 6-mercaptopurine on the fetal rat central nervous system: a light-microscopic study.

Wistar rats were administered single doses of 16 or 50 mg/kg 6-mercaptopurine (6-MP) on day 12 of pregnancy. Necrosis in the fetal forebrain and spinal cord was studied by light microscope 6, 12, 14, 48, 72, and 81 h and 8 days afterward. The extent of necrosis was dose dependent. The first necroses were seen after 24 h, regardless of location (brain, spinal cord) or dose; but the extent was greatest after 48 h. All necrotic cells had a typical appearance; they were ballooned and often fragmented, their nuclei were darkly colored and frequently pyknotic, and they were often karyorhexic. Necroses appeared almost exclusively at sites of beginning cellular differentiation, i.e., in the intermediate zone. In the spinal cord the ventricular zone was also necrotic and the alar plate (dorsal horn) always affected. Phagocytizing cells (macrophages) appeared in the spinal cord after 48 h and in the brain after 72 h. After 81 h all the necrotic material had been phagocytized, at which time there was a massive congestion of the extra- and intracerebral vessels. Hemorrhages appeared in defined localizations. Eight days after exposure to 16 mg/kg 6-MP fetuses no longer showed any visible deviations. Fetuses exposed to 50 mg/kg showed deviations in the cytoarchitecture of the neopallium: an extremely broadened ventricular zone, few cells in the intermediate zone, and extensive rarefaction cells in the cortical plate with no clear layer structure. In the spinal cord, cleft formations were especially noticeable in the dorsal-horn region. All fetuses showed a hydrocephalus externus after 50 mg/kg. The mechanism leading to necrosis is discussed.     

Effects of the cytostatic drug cis-platinum on the developing neocortex of the mouse

The effects of the new cytostatic drug cis-diamminedichloroplatinum(II) (cis-platinum) on the developing neocortex of NMRI mouse embryos or fetuses were investigated using light- and electron-microscopic methods. Single doses of 20 mg cis-platinum/kg were applied intraperitoneally on day 10, 11, . . ., or 16 of gestation. After treatment on day 10 or 11-i.e., during the phase of organogenesis-no morphological alterations could be detected in the neuroepithelium. However, after treatment on day 12 or later, the mitotic activity was markedly reduced and a great number of cells had become necrotic within 12-24 h after application of the drug. At the ultrastructural level, the development of necroses began with a condensation of the chromatin, culminating in the formation of large condensation plaques and shrinkage and fragmentation of the cytoplasm. The observed necroses can be classified according to Schweichel and Merker as type I necroses. It is argued that the apparent teratogenic inefficiency of cis-platinum on days 10 and 11 of murine pregnancy is caused by the inability of cis-platinum to pass the placental barrier at this stage of pregnancy.     

Corticosterone induction of cleft palate in mice dosed with orciprenaline sulfate

Orciprenaline sulfate is a beta-adrenoceptor stimulant chemically described as 1-(3,5-dihydroxyphenyl)-1-hydroxy-2-isopropylaminoethane sulfate (Alupent). The drug has broncho-dilating activity and has been developed in numerous countries since 1961. The purpose of these studies was to investigate the teratogenic potential of orciprenaline and its mode of action in pregnant Jcl:ICR mice, when administered during the period of organogenesis and, more systematically, during the critical period of palate formation. Daily doses of 5, 50, and 500 mg/kg were given orally by gavage to mice on days 6-15, 11-13, or on day 12 of gestation. Additional studies were done to evaluate the maternal cardiotoxic action of orciprenaline and its effects on adrenal cortex and endogenous serum corticosterone. Five mg/kg triamcin-olone acetonide, a glucocorticoid, were given subcutaneously as a positive control causing 100% cleft palate. Myocardial necroses occurred in pregnant mice only after 500 mg/kg orciprenaline had been given, and a significant increase in cleft palate occurred if exposure took place during days 11-13 or day 12 of gestation. This increase in cleft palate can be explained by the teratogenic effect of an elevated maternal serum corticosterone level 1 hr after orciprenaline treatment, about three times the control value.     

Effect of 6-mercaptopurine on 65Zn distribution in the pregnant rat

The effect of 6-mercaptopurine (6-MP) on the distribution of gavaged 65Zn in maternal and embryonic tissues of Sprague-Dawley rats was examined 24 hr after injection of the drug on day 13 of pregnancy. 6-MP injection resulted in a significantly higher retention of counts of 65Zn in maternal liver and lower counts in maternal plasma, uterus, placenta, and embryo than in controls. Compared to controls, gel chromatography of maternal liver from 6-MP injected dams showed higher counts associated with a protein peak of molecular weight 6,000-8,000, the approximate molecular weight of the zinc-binding protein metallothionein. These results support the idea that the zinc deficiency, which is observed in day 21 fetuses from dams injected with 6-MP during midgestation, may be the result of a drug-induced sequestering of zinc into maternal liver followed by a decrease in maternal plasma zinc and subsequent reduction in fetal zinc uptake. We suggest that this 6-MP-associated redistribution of zinc into maternal liver may be due to induction of maternal metallothionein synthesis by the drug.     

Study of nucleic acid synthesis in rat embryos in relation to phase-specific characteristics of teratogenic effect of chloridine]

The maximal rate of incorporation of 32P-phosphate, 14C-formate and 14C-thymidine in DNA was recorded on the 13th day of development in the rat embryos and that of 14C-formate and 32P-phosphate in RNA and nucleotides of the acid-soluble fraction on the 12th day. The maximal incorporation of 14C-formate was recorded later: on the 15-16th days. Chloridin inhibited the incorporation of 14C-formate in DNA at all developmental stages, irrespective of the sensitivity of embryos to its teratogenic effect. The period of the maximal rate of DNA synthesis coincides with that of highest teratogenic activity of the drug. A suggestion is put forward to the effect that quantitative differences in the intensity of DNA synthesis at different stages of organgenesis provide one of the main causes of differential sensitivity of embryos to the teratogenic effect of inhibitors of nucleic acid synthesis.     

Relationship of dietary zinc to 6-mercaptopurine teratogenesis and DNA metabolism in the rat

The possible interaction between the level of maternal dietary zinc and the teratogenic activity of 6-mercaptopurine was investigated. Pregnant Sprague-Dawley rats were fed diets containing 9,100 or 1,000 ppm zinc from day zero of pregnancy and were given a single intraperitoneal injection of 6-MP (55mg/kg) on day 11. At term, females in the group fed 1,000 ppm zinc (a high intake) showed less pronounced effects on reproduction and embryogenesis than did those fed 9 ppm (marginally deficient) or 100 ppm (normal) zinc. Embryos examined on day 12 of gestation had similar concentrations of protein and RNA; however, the DNA content was lower and the incorporation of 3H-thymidine was greater in the drug treated groups than in non-drug treated controls. These results indicate that 6-mercaptopurine is acting to alter embryonic DNA metabolism and that high levesl of dietary zinc may ameliorate some of the deleterious effects of this drug on embryonic and maternal toxicity.     

Variability in the developmental toxicity of bropirimine with the day of administration

The aim of this study was to determine the mechanism by which bropirimine exerts its developmental toxicity. This drug is an immunomodulator and interferon inducer with antiviral and antitumor activities in experimental models. Timed-pregnant Upj:TUC(SD)spf (Sprague-Dawley) rats were given a single oral (gastric intubation) dose of bropirimine at 200 or 400 mg/kg (doses as high as 100 mg/kg/day have been employed in human cancer trials) on days 5, 6, 7, 8, 9, 10, 11, or 12 of gestation and in a second experiment on day 12, 13, 14, 15, 16, 17, 18, or 19 of gestation. The dams were killed 24 hours after dosing and their uterine contents examined. In a third experiment, bropirimine (400 mg/kg) was administered on day 4 of gestation and the uteri of different groups were examined on day 8, 9, 10, 11, or 12 of gestation. Serum progesterone levels were measured at sacrifice. In the first two experiments a battery of hematologic/clinical chemistry assays also were performed. In all three experiments, bropirimine-related maternal toxicity was observed; such toxicity was characterized by significant decreases in weight gain, relative to the concurrent vehicle controls, as well as significant differences in several blood parameters including platelets, white blood cells, alanine aminotransferase, and aspartate transaminase. In the first experiment, bropirimine treatment on day 11, but not day 12, resulted in significant decreases in the mean number of live embryos per litter. In the second experiment, significant decreases in the number of live fetuses per litter occurred 24 hours after dosing on day 18 (200 and 400 mg/kg groups) or day 19 (400 mg/kg group). Decreases in serum progesterone appeared to correlate well with the embryolethal effects seen after treatment between days 6 and 11 of gestation, but not with the fetal lethality seen when treatment was given on day 17 or 18. The decreases in serum progesterone levels found most likely were the result of a luteolytic effect, although it is unknown if bropirimine has a direct or indirect effect on the corpora lutea. In the third experiment, bropirimine treatment on day 4 of gestation resulted in only slight preimplantational losses, but significant decreases were found in mean number of live embryos per litter after day 9. Uterine decidual necrosis has been observed in the first experiment where bropirimine was given on day 11; however, treatment on day 4 resulted in an apparent decrease in decidual development but not necrosis.     

Developmental-stage-dependent radiosensitivity of neural cells in the ventricular zone of telencephalon in mouse and rat fetuses

Pregnant ICR mice were treated with single whole-body X-radiation at a dose of 0.24 Gy on day 10, 13, or 15 of gestation. Fetuses were obtained from mothers during 1 and 24 hours after irradiation. Pyknotic cells in the ventricular zone of telencephalon were counted in serial histological sections. Incidence of pyknotic cells peaked during 6 and 9 hours after irradiation in each gestation day group. Then, dose-response curves were obtained 6 hours after 0-0.48 Gy of irradiation. All three dose-response curves showed clear linearity in the dose range lower than 0.24 Gy. Ratios of radiosensitivity estimated from the slopes of dose-response curves in day 10, 13, and 15 groups were 1, 1.4, and 0.4, respectively. These demonstrated that ventricular cells in the day 13 fetal telencephalon were the most radiosensitive among the three different age groups. In order to confirm the presence of the highly radiosensitive stage common to mammalian cerebral cortical histogenesis, pregnant F344 rats were treated with single whole-body gamma-irradiation at a dose of 0.48 Gy on day 13, 14, 15, 17, or 19 of gestation. The incidence of pyknotic cells in the ventricular zone of telencephalon was examined microscopically during 1 and 24 hours after irradiation. The peak incidence was shown 6 hours after irradiation in all the treated groups, and the highest peak incidence was shown in day-15-treated group. The developmental stage of telencephalon of day 15 rat fetuses was comparable to that of day 13 mouse fetuses. Thus, the highest radiosensitivity in terms of acute cell death was shown in the same developmental stage of brain development, i.e., the beginning phase of cerebral cortical histogenesis, in both mice and rats.     

The initial accumulation of carbamoylphosphate synthetase in embryonic rat hepatocytes, and the cell cycle

The hormone-induced expression of the hepatocyte-specific enzyme carbamoylphosphate synthetase can take place in each phase of the cell cycle and is not restricted to the G1 or the G0 phase. To arrive at this conclusion, the cell cycle parameters of embryonic day 14 rat hepatocytes in vitro were determined by autoradiography after labeling with (3H)-TdR or with (3H)- and (14C)-TdR. An S-phase of approximately 14 h, a G2 + M-phase of 8 h, a G1-phase of 8-13 h and a total cell cycle of 30-35 h were measured. Freshly isolated embryonic hepatocytes have exponential growth parameter values, but shift to a steady state growth under culture conditions in the presence of hormones (glucocorticosteroids, thyroid hormones and cyclic AMP). The length of the S-phase and of the total cell cycle remain constant during the culture time. The time course of accumulation of carbamoylphosphate synthetase protein in embryonic hepatocytes is identical in all phases of the cell cycle. It is suggested that hormones, in particular glucocorticosteroids, simultaneously and independently regulate growth mode and gene expression in developing hepatocytes. The nucleotide-analogue 5-bromodeoxyuridine inhibits the hormone-induced expression of carbamoylphosphate synthetase only in cells that are exposed to the drug during early S-phase, indicating replication of the carbamoylphosphate synthetase gene in that part of the cell cycle.     

Comparative study of cell cycle kinetics and induction of apoptosis or necrosis after exposure of human Mono Mac 6 cells to radiofrequency radiation

The possible harmful effects of radiofrequency electromagnetic fields (RF EMFs) are controversial. We have used human Mono Mac 6 cells to investigate the influence of RF EMFs in vitro on cell cycle alterations and BrdU uptake, as well as the induction of apoptosis and necrosis in human Mono Mac 6 cells, using flow cytometry after exposure to a 1,800 MHz, 2 W/kg specific absorption rate (SAR), GSM-DTX signal for 12 h. No statistically significant differences in the induction of apoptosis or necrosis, cell cycle kinetics, or BrdU uptake were detected after RF EMF exposure compared to sham or incubator controls. However, in the positive control cells treated with gliotoxin and PMA (phorbol 12 myristate-13 acetate), a significant increase in apoptotic and necrotic cells was seen. Cell cycle analysis or BrdU incorporation for 72 h showed no differences between RF EMF- or sham-exposed cells, whereas PMA treatment induced a significant accumulation of cells in G(0)/G(1)-phase and a reduction in S-phase cells. RF EMF radiation did not induce cell cycle alterations or changes in BrdU incorporation or induce apoptosis and necrosis in Mono Mac 6 cells under the exposure conditions used.     

6-Mercaptopurine reduces cytokine and Muc5ac expression involving inhibition of NFκB activation in airway epithelial cells

Background

Mucus hypersecretion and excessive cytokine synthesis is associated with many of the pathologic features of chronic airway diseases such as asthma. 6-Mercaptopurine (6-MP) is an immunosuppressive drug that is widely used in several inflammatory disorders. Although 6-MP has been used to treat asthma, its function and mechanism of action in airway epithelial cells is unknown.

Methods

Confluent NCI-H292 and MLE-12 epithelial cells were pretreated with 6-MP followed by stimulation with TNFα or PMA. mRNA levels of cytokines and mucins were measured by RT-PCR. Western blot analysis was performed to assess the phosphorylation of IκBα and luciferase assays were performed using an NFκB reporter plasmid to determine NFκB activity. Periodic Acid Schiff staining was used to assess the production of mucus.

Results

6-MP displayed no effect on cell viability up to a concentration of 15 μM. RT-PCR analysis showed that 6-MP significantly reduces TNFα- and PMA-induced expression of several proinflammatory cytokines in NCI-H292 and MLE-12 cells. Consistent with this, we demonstrated that 6-MP strongly inhibits TNFα-induced phosphorylation of IκBα and thus attenuates NFκB luciferase reporter activity. In addition, 6-MP decreases Rac1 activity in MLE-12 cells. 6-MP down-regulates gene expression of the mucin Muc5ac, but not Muc2, through inhibition of activation of the NFκB pathway. Furthermore, PMA- and TNFα-induced mucus production, as visualized by Periodic Acid Schiff (PAS) staining, is decreased by 6-MP.

Conclusions

Our data demonstrate that 6-MP inhibits Muc5ac gene expression and mucus production in airway epithelial cells through inhibition of the NFκB pathway, and 6-MP may represent a novel therapeutic target for mucus hypersecretion in airway diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0236-0) contains supplementary material, which is available to authorized users.     

Acinar cell proliferation in the parotid and submandibular salivary glands of the neonatal rat

Abstract. Although the rat salivary glands are deficient in acini at birth, acinar cells proliferate rapidly during the early post-natal period. The pattern of acinar cell proliferation was analysed in the parotid and submandibular glands of neonatal rats from day of birth until day 34. Mitotic and [³H]thymidine ([³H]TdR) labelling indices of the two glands show distinctly different patterns. Analysis of cell division in the rat parotid gland demonstrated a peak of mitotic index at 14 days (2.9 ± 0.4%) and labelling index at 16 days (25.2 ± 2.1%). Submandibular gland acinar cell proliferation reaches a zenith between 7–8 days; labelling index (14.2 ± 1.1%) and mitotic index (2.3 ± 0.3%). Cell proliferation decreases rapidly in both glands after reaching a peak in activity. Gland size increases more rapidly in the submandibular gland which correlates with the earlier shift from cell proliferation to differentiation which occurs in this organ. Circadian rhythms of [³H]TdR incorporation were also investigated in this study. A circadian rhythm of [³H]TdR incorporation into DNA occurs at 15 days after birth with a peak at 06.00 hours in both glands and a trough occurring at 15.00 hours in parotid gland and 18.00 hours in the submandibular gland. Determination of specific activity of DNA (ct/min per μg DNA) on days 8, 10, 12, 13, 14, 15, and 16 after birth at 06.00 and 15.00 hours indicated that a circadian rhythm in [³H]TdR incorporation into DNA began on day 14. The developmental switch from suckling to solid food may be an initiating factor in the sychronization of the circadian rhythm in cell proliferation.     

Primary antibody response studied by using inhibitors of nucleic acid synthesis

Inhibitors of nucleic acid synthesis were tested for the effect on the primary antibody response. Antibody formation by adult spleen cells mixed with antigenin vitro and transferred to newborn rabbits was completely suppressed by 6-mercaptopurine administered in the initial phase of antibody induction. The extent of inhibition decreased proportionately to the time interval between cell transfer and treatment with 6-MP. Different sensitivity of immunologically competent cells towards 6-MP at various periods of differentiation and interference of 6-MP with synthesis of specific ribonucleic acid is suggested. Actinomycin D did not show any inhibitory effect on the primary antibody responsein vivo which may be due either to the toxicity of the drug or to some other mechanism of synthesis of immunoglobulins than is known for bacterial proteins. Mitomycin C was also ineffective in suppressing the inductive phase of antibody formation. From results with 6-MP and mitomycin C it is concluded that DNA synthesis and mitotic division are not essential steps in the induction of antibodies.     

Circadian Variations in Human Peripheral Blood on Days With and Without Bone Marrow Sampling and Relation to Bone Marrow Cell Proliferation

Fifteen bone marrow (BM) and venous blood circadian profiles were obtained from 13 diurnally-active, healthy men sampled every 4-5 h for 24 h. Peripheral blood (PB) was also sampled in subsets of 5 men either for 24 h immediately preceding the BM procedure or 5-6 months afterwards. Cortisol and white and red cell parameters were determined in PB. BM cell cycle distribution was investigated in parallel by flow cytometry for S-phase DNA of total mononuclear cells and subpopulations of erythroid and myeloid precursor cells. On a group basis, significant circadian rhythms were found in PB variables commonly referred to as "marker" rhythms (cortisol, total white cells [WBC], neutrophils [N], lymphocytes [L]), with acrophases less than 2 h apart between the contro l day prior to and during BM sampling. Thus, major, but relatively short-lasting physiological stress, like BM aspirations or blood sampling itself, although repeated several times over 24 h, seemed to have minor influence on these rhythms on days of the BM procedure. When comparing the times of highest or lowest values in PB with times of highest or lowest values in BM, several temporal relationships were found. Among other associations, timing of lowest values in WBC, N and L or highest values in cortisol was significantly predictive of highest values in myeloid cells occurring in the following 12 h, whereas highest values in erythroid cells occurred significantly more often in the 12 h interval beginning 4 h after the time of lowest values in WBC, L and N. The stability in the circadian rhythms of the PB variables suggests that information obtained on one day can be used to guide procedures on the next, such as BM myelotoxic chronotherapy or BM harvesting.     

Studies on the Photoperiodic Responses in Short-Day Plant Helianthus tubevotus

Plants of Helianthus tuberosus, variety white tuber, were treated with various daylengths of 4, 6, 8, 10, 11, 12, 13, 14, 15, 18 h. for 25 days as soon as six leaves on a plant appeard Irradiation for 6–13 h per day induced the plants to form flower buds and flowering, daylength with 14 h or longer kept the plants in vegetative growth. The experiments showed that this variety of Helianthus tuberosus required short days for flowering and the critical daylength was about 13 h. The plants were treated with short days for different durations. At least 17 days were required, Formation of flower buds and flowering had positive correlation with the number of short days over 17 days. After short-day induction, the shorter the daylength is, the more the flower buds inverted. Long-day treatment after an appropriate period of short days wouid reduce the number of flower and induce new vegetative branches from flowering granehes.     

Role of 6-Mercaptopurine in the potential therapeutic targets DNA base pairs and G-quadruplex DNA: insights from quantum chemical and molecular dynamics simulations

The theoretical studies on DNA with the anticancer drug 6-Mercaptopurine (6-MP) are investigated using theoretical methods to shed light on drug designing. Among the DNA base pairs considered, 6-MP is stacked with GC with the highest interaction energy of –46.19 kcal/mol. Structural parameters revealed that structure of the DNA base pairs is deviated from the planarity of the equilibrium position due to the formation of hydrogen bonds and stacking interactions with 6-MP. These deviations are verified through the systematic comparison between X–H bond contraction and elongation and the associated blue shift and red shift values by both NBO analysis and vibrational analysis. Bent’s rule is verified for the C–H bond contraction in the 6-MP interacted base pairs. The AIM results disclose that the higher values of electron density (ρ) and Laplacian of electron density (?²ρ) indicate the increased overlap between the orbitals that represent the strong interaction and positive values of the total electron density show the closed-shell interaction. The relative sensitivity of the chemical shift values for the DNA base pairs with 6-MP is investigated to confirm the hydrogen bond strength. Molecular dynamics simulation studies of G-quadruplex DNA d(TGGGGT)₄ with 6-MP revealed that the incorporation of 6-MP appears to cause local distortions and destabilize the G-quadruplex DNA.     

Comparative effects of TGFβ on proliferation of 7- and 14-day-old chick embryo fibroblasts and lack of involvement of the ODC/PA system in the TGFβ signaling pathway

The growth regulatory activity of transforming growth factor β (TGFβ) on chick embryo skin fibroblasts was compared in two developmental ages, days 7 and 14. The time course of ³H-thymidine incorporation, an S-phase marker of replication, was determined during 36 hr of TGFβ treatment. Seven-day-old cells showed a prereplicative phase of 6 hr, and 14-day-old cells showed a prereplicative phase of 12 hr. DNA synthesis peaked at 24 hr in 7-day-old fibroblasts and was 10 times higher than that in 14-day-old fibroblasts. Ornithine decarboxylase (ODC) activity and content of the natural polyamines spermine (Spm), spermidine (Spd), and putrescine (Put) differed during cell cycle. ODC activity peaked at 12 hr in 7-day-old cells and at 6 hr in 14-day-old cells. Its level was two times higher at day 7 and was associated with a greater content of ODC mRNA. The maximum of polyamine (PA) concentration was determined after 12 hr of treatment in 7-day-old cells and after 36 hr in 14-day-old cells. These findings indicate that the TGFβ proliferative response of embryo fibroblasts changes during development and is associated with activation of the ODC/PA system. Cotreatment with α-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ODC, did not reduced growth rate. Inhibition of ODC resulted in levels of Put and Spd comparable to that of quiescent fibroblasts, whereas Spm concentration remained higher. Because an altered ODC metabolism does not convey the effects of TGFβ on DNA synthesis, the ODC/PA system may not play a role in the pathway of TGFβ signaling. J. Cell. Physiol. 178:304–310, 1999. © 1999 Wiley-Liss, Inc.     

Pteridines are produced during interleukin 2-induced T-cell proliferation and modulate transmission of this signal

Pteridine levels of interleukin 2 (IL-2) receptor+ T-cell populations have been determined by HPLC after iodine oxidation; neopterin was monitored in the culture supernatants by radio-immunoassay. Upon addition of IL-2, cellular levels of biopterin and 6-hydroxymethylpterin rise transiently from 0.02 to 0.9 pmol/10(6) cells, cellular levels of neopterin from 1.5 to 4.1 pmol/10(6) cells. They peak at 8 and 13 h, respectively, after exposure to IL-2. Neopterin is not accumulated in the culture supernatant. DNA synthesis in T cells begins 10-12 h after adding the lymphokine and the portion of cells that undergo S-phase transition gradually increases during the subsequent 10 h. Entry into DNA synthesis phase is markedly accelerated if IL-2 is supplied together with tetrahydrobiopterin (0.8-1.6 X 10(-6) M) and the kinetics of entry into the S-phase transition during the period of 6-20 h become linear. This indicates that tetrahydrobiopterin modulation of IL-2 activity (Ziegler, I. et al. Naturwiss 72 (1985) 330) is an early event occurring during IL-2 signal transmission.     

Modification of immune reactions by antigen-immunosuppressive agent conjugates. V. Studies on antigen-specific activity of 6-mercaptopurine bovine gamma globulin conjugates on the humoral immune response in rabbits]

Rabbits treated daily and for seven consecutive days with 6-mercaptopurine bovine gamma globulin conjugates (MPI--n-BGG; 'I'--characterizes the king of chemical binding and 'n' the number of coupled MP-residues per one mole BGG) show an altered immunological reactivity. A following intradermal immunization with BGG alum adsorbate results in a suppressed anti BGG antibody production on the third day after antigen application (antibody titer 1:320, antibody titer of control animals--pretreated with BGG and uncoupled 6-MP equals 1:5120). Already three days later the antibody titers of the test groups show a significant increase and are two dilution stages higher than the titers of the controls. A suppressive effect on the third day is induced by MPI--13-BGG, MPI--26-BGG, MPI--36-BGG and MPI--46-BGG; the later adjuvant effect can only be seen in the MPI--26-BGG, MPI--36-BGG and MPI--46-BGG but not in the MPI--13-BGG pretreated animal group. While the short time suppression was antigen specific--the humoral immune response against a second unrelated antigen was not reduced--the adjuvans effect was not antigen specific. A pretreatment with the substances mentioned above results in an increased anti BGG and anti HSA serum antibody level. Comparing investigations on the unspecific immunosuppression in rabbits by 6-mercaptopurine shows that application of 10 mg 6-MP/kg/day for seven days at first leads to a suppression but later on to an enhancement of antibody production. Application of 10 mg 6-MP/kg/day for 10 days results in a long lasting suppression without enhancement effect. As a reason for these differences the different catabolism of immunosuppressive agent and antigen is discussed. For the phenomena following antigen specific immunosuppression, similar mechanisms can be responsible.     

Anthelmintic effects of bithionol, paromomycin sulphate, flubendazole and mebendazole on mature and immature Hymenolepis nana in mice

The anthelmintic effects of anti-tapeworm drugs, bithionol, paromomycin sulphate, flubendazole and mebendazole on immature and mature Hymenolepis nana in mice were compared. Immature worms were not affected by paromomycin sulphate or flubendazole administered for 12 consecutive days (days one to 12 after infection) at 100 mg/kg/day but 48% and 100% of H. nana were eliminated from mice by bithionol and mebendazole respectively, at the same dosage regimen. Bithionol, paromomycin sulphate, flubendazole and mebendazole given at 100 mg/kg/day for five consecutive days (days 12 to 16 after infection) eliminated 32%, 29%, 36% and 100% of mature worms respectively. 10 and 20 mg of mebendazole/kg/day for five consecutive days (days 12 to 16 after infection) had little effect on mature worms whereas 50 and 100 mg/kg/day for the same period eliminated 99% and 100% of mature worms, respectively. ED50 of mebendazole in the elimination of mature H. nana was 14 or 15 mg/kg/day for five days from the reduction in dry weight or in number of worms recovered respectively. The effects of mebendazole given 2 to 4 days, 8 to 10 days or 13 to 15 days after infection at 100 mg/kg/day were compared. Very low, if any, activity of the drug given 2 to 4 days after infection was seen, whereas the drug given 8 to 10 days or 13 to 15 days after infection eliminated 84% and 86% of H. nana respectively.