Search

Objective: Our aim was to investigate the influence of thymic polypeptides on pain sensitivity and to analyze a possible role of the opioid system in the implementation of the analgesia caused by immobilization stress., Methods: The study was performed on male Wistar rats at the Moscow state University named after M. V. Lomonosov. We studied effects of thymus peptides: thymuline (0.15 mg/kg), fraction 5 thymosin (0.25 microgram/kg) and cattle thymus extracted product (CTEP) (0.5 mg/kg) on pain sensitivity in rats using test "tail flick" without stress, with acute (3 h) and sub acute (12 h) immobilization stress. The comparison groups were animals treated with saline and spleen polypeptides., Results: It is shown that preparations of thymus increase the threshold of pain sensitivity in the intact animals. Immobilization stress duration 3 and 12 h in thymus peptides treated rats caused a less pronounced increase in pain threshold than in the control groups (immobilization stress 3 h: CTEP--p = 0.025, thymuline--p = 0.022, fraction 5 thymosin--p = 0.033; immobilization stress 12 h: CTEP--p = 0.034, thymuline--p = 0.027, fraction 5 thymosin--p = 0.036). The opioid receptor blocker naloxone (1 mg/kg) did not completely block the stress-induced analgesia, indicating the presence of both opioid and non -opioid components in this state. In thymus peptides treated rats, opioid component was less pronounced than in the control groups (CTEP--p = 0.031, thymuline--p = 0.026, fraction 5 thymosin--p = 0.029)., Conclusion: Pre-activation of the opioid system by the thymus polypeptides leads to an increase in the share of non-opioid component of the stress-induced analgesia and prevents the depletion of the opioid system in immobilization stress.

Diabetes is a debilitating disease with chronic evolution that affects many tissues and organs over its course. Thymus is an organ that is affected early after the onset of diabetes, gradually involuting until it loses most of its thymocyte populations. We show evidence of accumulating free fatty acids with generation of eicosanoids in the diabetic thymus and we present a possible mechanism for the involution of the organ during the disease. Young rats were injected with streptozotocin and their thymuses examined for cell death by flow cytometry and TUNEL reaction. Accumulation of lipids in the diabetic thymus was investigated by histology and electron microscopy. The identity and quantitation of accumulating lipids was done with gas chromatography-mass spectrometry and liquid chromatography. The expression and dynamics of the enzymes were monitored via immunohistochemistry. Diabetes causes thymus involution by elevating the thymocyte apoptosis. Exposure of thymocytes to elevated concentration of glucose causes apoptosis. After the onset of diabetes, there is a gradual accumulation of free fatty acids in the stromal macrophages including arachidonic acid, the substrate for eicosanoids. The eicosanoids do not cause thymocyte apoptosis but administration of a cyclooxygenase inhibitor reduces the staining for ED1, a macrophage marker whose intensity correlates with phagocytic activity. Diabetes causes thymus involution that is accompanied by accumulation of free fatty acids in the thymic macrophages. Excess glucose is able to induce thymocyte apoptosis but eicosanoids are involved in the chemoattraction of macrophage to remove the dead thymocytes.

Different mechanisms including oxidative stress are proposed for amyloid-β peptide (Aβ) neurotoxicity, and here we contribute to demonstrate that nitro-oxidative stress is playing a key role. Yeasts are a well-known model for H2O2 toxicity. Interestingly, yeast cell wall prevents interaction of Aβ fibrils with membrane receptors or calcium channels and we found a significant viability reduction in yeasts when challenged with Aβ fibrils. Furthermore, iron and copper chelators, as well as the antioxidants glutathione and trolox, were neuroprotective on neuroblastoma cells and mouse hippocampal neurons challenged with Aβ fibrils. Glutathione prevents the oxidation, glycation and nitrotyrosination of cell proteins induced by Aβ. Trolox protected neurons in cell viability studies, maintaining the vesicular transport integrity and preventing the trigger of apoptotic mechanisms. Interestingly, we have also found that brain derived neuronal factor (BDNF) and neurotrophin-3 (NT-3) were able to protect mouse hippocampal and cortical neurons against H2O2 and Aβ fibrils. Considering that superoxide anion, produced by Aβ cell damage, and nitric oxide, whose production is altered in AD, react to form the highly reactive peroxynitrite anion, we studied the role of trolox to ameliorate the peroxynitrite cell damage. Finally, one of the major proteins to be nitrotyrosinated in AD, the triose phosphate isomerase (TPI) was assayed searching for a denitrase activity that could reverse intracellular nitrotyrosination. We have found that human neuroblastoma SH-SY5Y cells express a constitutive denitrase activity that partially denitrated nitro-TPI. Altogether, our results support a key role of nitro-oxidative stress in the neuronal damage induced by Aβ fibrils.

Objective: To examine determinants of thymus size at age 6 months and investigate whether thymus size at this age is a determinant of subsequent mortality., Study Design: Thymus size was measured by transsternal sonography in 923 6-month-old children participating in a measles vaccination trial in Guinea-Bissau., Results: Thymus size was strongly associated with anthropometric measurements. Boys had larger thymuses than girls, controlling for anthropometry. Crying during sonography made the thymus appear smaller. Children who were not vaccinated with Bacille Calmette-Guérin (BCG) or were vaccinated with BCG in the preceding 4 weeks before inclusion into the study had larger thymuses. Children who had malaria or had been treated with chloroquine or Quinimax in the previous week before inclusion had smaller thymuses. Controlled for background factors associated with thymus size and mortality, small thymus size remained a strong and independent risk factor for mortality (hazard ratio = 0.31; 95% confidence interval = 0.18 to 0.52)., Conclusions: Small thymus size at age 6 months is a strong risk factor for mortality. To prevent unnecessary deaths, it is important to identify preventable factors predisposing to small thymus size.

This review is dedicated to John Newsom-Davis, who was an exceptional colleague and friend, always exchanging ideas with respect and consideration. We shall not forget his involvement and passion in search for the truth on the role of thymectomy in the management of Myasthenia Gravis (MG). In this short review, we shall summarize what we learnt from DNA microarrays applied to MG thymus. We shall focus on three main comparisons of the thymic transcriptomes: 1) highly hyperplastic MG patients versus non-MG adults; 2) corticosteroid-treated versus untreated seropositive MG patients; and 3) seronegative versus seropositive MG patients.

The thymus is believed to play an important role in the pathogenesis of myasthenia gravis (MG). The 80% of MG patients with anti-acetylcholine receptor autoantibodies fall into three clinical subgroups: 1) thymoma; 2) early-onset MG (

Here we show that in myasthenic thymus several cell types, including thymic epithelial cells (TEC) and immune cells, were the source and the target of the neurotrophic factor brain-derived growth factor (BDNF). Interestingly, many actively proliferating medullary thymocytes expressed the receptor TrkB in vivo in involuted thymus, while this population was lost in hyperplastic or neoplastic thymuses. Furthermore, in hyperplastic thymuses the robust coordinated expression of BDNF in the germinal centers together with the receptor p75NTR on all proliferating B cells strongly suggests that this factor regulates germinal center reaction. Finally, all TEC dying of apoptosis expressed BDNF receptors, indicating that this neurotrophin is involved in TEC turnover. In thymomas both BDNF production and receptor expression in TEC were strongly hindered. This may represent an attempt of tumour escape from cell death.

Background: Thymostimulin is a thymic peptide fraction with immune-mediated cytotoxicity against hepatocellular carcinoma in vitro. In a phase II trial, we investigated safety and efficacy including selection criteria for best response in advanced or metastasised hepatocellular carcinoma., Methods: 44 patients (84 % male, median age 69 years) not suitable or refractory to conventional therapy received thymostimulin 75 mg subcutaneously five times per week for a median of 8.2 months until progression or complete response. 3/44 patients were secondarily accessible to local ablation or chemoembolisation. Primary endpoint was overall survival, secondary endpoint tumor response or progression-free survival. A multivariate Cox's regression model was used to identify variables affecting survival., Results: Median survival was 11.5 months (95% CI 7.9-15.0) with a 1-, 2- and 3-year survival of 50%, 23% and 9%. In the univariate analysis, a low Child-Pugh-score (p = 0.01), a low score in the Okuda- and CLIP-classification (p < 0.001) or a low AFP-level (p < 0.001) were associated with better survival, but not therapy modalities other than thymostimulin (p = 0.1) or signs of an invasive HCC phenotype such as vascular invasion (p = 0.3) and metastases (p = 0.1). The only variables independently related to survival in the Cox's regression model were Okuda stage and presence of liver cirrhosis (p < 0.01) as well as response to thymostimulin (p < 0.05). Of 39/44 patients evaluable for response, two obtained complete responses (one after concomitant radiofrequency ablation), five partial responses (objective response 18%), twenty-four stable disease (tumor control rate 79%) and eight progressed. Median progression-free survival was 6.4 months (95% CI 0.8-12). Grade 1 local reactions following injection were the only side effects., Conclusion: Outcome in our study rather depended on liver function and intrahepatic tumor growth (presence of liver cirrhosis and Okuda stage) in addition to response to thymostimulin, while an invasive HCC phenotype had no influence in the multivariate analysis. Thymostimulin could therefore be considered a safe and promising candidate for palliative treatment in a selected target population with advanced hepatocellular carcinoma, in particular as component of a multimodal therapy concept., Trial Registration: Current Controlled Trials ISRCTN29319366.

Identification of a thymus-seeding progenitor originating from human bone marrow (BM) constitutes a key milestone in understanding the mechanisms of T cell development and provides new potential for correcting T cell deficiencies. We report the characterization of a novel lymphoid-restricted subset, which is part of the lineage-negative CD34(+)CD10(+) progenitor population and which is distinct from B cell-committed precursors (in view of the absence of CD24 expression). We demonstrate that these Lin(-)CD34(+)CD10(+)CD24(-) progenitors have a very low myeloid potential but can generate B, T, and natural killer lymphocytes and coexpress recombination activating gene 1, terminal deoxynucleotide transferase, PAX5, interleukin 7 receptor alpha, and CD3epsilon. These progenitors are present in the cord blood and in the BM but can also be found in the blood throughout life. Moreover, they belong to the most immature thymocyte population. Collectively, these findings unravel the existence of a postnatal lymphoid-polarized population that is capable of migrating from the BM to the thymus.

The level of natural apoptosis in rat thymus on day 18 of embryo development attained 25%, while at subsequent terms it was about 5%. In the spleen, this parameter gradually decreased from 15 to 37% starting from day 18 of embryo development to postnatal day 30. Tactivin prevented the development of dexamethasone-induced apoptosis in thymocytes of 30-day-old rats, but had no effect on spontaneous apoptosis. Tactivin can be used as a modulator of apoptotic processes.

The alternative TrkAIII splice variant is expressed by murine and human thymus. Alternative TrkAIII splicing predominates in postembryonic day E13 (E17 and E18), postnatal murine (3 week and 3 month) and human thymuses, with TrkAIII mRNA expressed by selected thymocyte subsets and thymic epithelial cells (TECs) and a 100 kDa immunoprecipitable TrkAIII-like protein detected in purified thymocyte and whole thymus extracts. FACS and immunohistochemical analysis indicate a non-cell surface localisation for the TrkAIII-like protein in cortical CD4+/CD8+ double positive and, to a lesser extent, single positive thymocyte subsets at the cortex/medulla boundary and in Hassle's corpuscles, reticular epithelial and dendritic cells of the thymic medulla. TrkA(I/II) expression, on the other hand, predominates in sub-capsular regions of the thymus. TrkAIII-like immunoreactivity at the cortex/medulla boundary associates with regions of thymocyte proliferation and not apoptosis. A potential role for thymic hypoxia in thymocyte alternative TrkAIII splicing is supported by reversal to TrkAI splicing by normoxic but not hypoxic culture and induction of Jurkat T cell alternative TrkAIII splicing by the hypoxia mimic CoCl2. In contrast, TEC expression of TrkAIII predominates in both normoxic and hypoxic culture conditions. The data support a potential role for TrkAIII in thymic development and function, of particular relevance to intermediate stage CD4+/CD8+ thymocyte subsets and TECs, which potentially reflects a reversible thymocyte and more permanent TEC adaptation to thymic environment. Since intracellular TrkAIII neither binds nor responds to NGF and can impede regular NGF/TrkA signalling (Tacconelli et al., Cancer Cell, 2004), its expression would be expected to provide an alternative and/or impediment to regular NGF/TrkA signalling within the developing and developed thymus of potential functional importance.

Changes in chicken embryo thymus after partial decerebration (including the hypophysis) and hypophyseal allograft were investigated. Chicken embryos were partially decerebrated at 36-40 hr of incubation and on day 12 received a hypophyseal allograft from 18-day-old donor embryos. The embryonic thymuses were collected on day 18 and examined with histological methods, tested for the anti-thymostimulin-like immune-reaction, and for histoenzymatic activities and compared with normal and sham-operated embryos at the same age. After partial decerebration, the thymic cortical and medullary compartments diminished markedly in size. Anti-thymostimulin, succinic dehydrogenase and ATPase enzymatic activities tested, yielded negative reactions. In partially decerebrated hypophyseal allografted embryos, the same thymic compartments improved and anti-thymostimulin-like immune-reaction and enzymatic activities partially recovered. These findings confirmed the key role of hypophysis in thymic ontogenic development and provided new information in metabolic enzymatic pathways and synthesis of a thymostimulin-like substance in the thymus.

Exogenous antioxidants, e.g. tocopherol, prevent undesirable changes in the thymus and accelerate its recovery after intensive physical exercise. Four weeks after the end of training (swimming) the general structure of the thymus and content of LPO products in rats treated with tocopherol corresponded to the control values, in contrast to animals receiving no correction.

The enzyme poly(ADP-ribose) glycohydrolase (PARG) catalyzes the hydrolysis of glycosidic bonds of ADP-ribose polymers, producing monomeric ADP-ribose units. Thus, in conjunction with poly(ADP-ribose) polymerase (PARP), PARG activity regulates the extent of in vivo poly(ADP-ribosyl)ation. Small molecule inhibitors of PARP and PARG have shown considerable promise in cellular models of ischemia-reperfusion injury and oxidative neuronal cell death. However, currently available PARG inhibitors are not ideal due to cell permeability, size, and/or toxicity concerns; therefore, new small molecule inhibitors of this important enzyme are sorely needed. Existing methodologies for in vitro assessment of PARG enzymatic activity do not lend themselves to high-throughput screening applications, as they typically use a radiolabeled substrate and determine product quantities through TLC analysis. This article describes a method whereby the ADP-ribose product of the PARG-catalyzed reaction is converted into a fluorescent dye. This highly sensitive and reproducible method is demonstrated by identifying two known PARG inhibitors in a 384-well plate assay and by subsequently determining IC(50) values for these compounds. Thus, this high-throughput, nonradioactive PARG assay should find widespread use in experiments directed toward identification of novel PARG inhibitors.

A major process through which the immune system becomes tolerant to self-proteins involves the deletion of self-reactive clones in the thymus, but clonal deletion is not single mechanisms of thymic tolerance. There is now much evidence that intrathymic antigen expression results in anergy induction of T helper type-1 (Th1) clones in the periphery. Blood-thymus barrier is most important structure for prevention of unwanted penetration of antigens into the thymus. Impermeability of the barrier restrain induction of acquired thymic tolerance on unwanted antigens like microbes and tumor cells. Nevertheless, one of most important mechanism of tumor and trophoblast escape is in anergy of Th1 cells and in Th2 cells domination. Many mechanisms are included in disarrangement of Th1/Th2 balance in pregnancy and tumor bearers, but one of possibility is in failure of blood-thymus barrier. Possible consequences of blood-thymus barrier failure are trophoblast-specific or tumor-specific antigens penetrate into the thymus, deletion or anergy of antigen-specific clones and acquired thymic tolerance induction. Blood-thymus barrier is variable structure in anatomical and functional sense so that in certain condition foreign antigens probably can permeate across the barrier. Probability that some factors like hormones, cytokines, prostaglandine and neuromediators can affect blood-thymus barrier permeability and contribute in mechanisms of trophoblast and tumor escape is real but relatively unexplored.

The Bursa of Fabricius of 15 day, 1-, 3-, and 6 month-old adult chickens (White Leghorn strain) were studied by histological and histochemical staining, histoenzymatic reactions (LDH, SDH, a-GPDH, NAD, NADPH, Ca++-dependent ATP-ase, pH 8.5) and by anti-thymostimulin immunoreaction. Positive reactions for mucopolysaccharides and enzymatic activities were located in the epithelia of the follicles, i.e. in follicle-associated-epithelium (FAE), inter-follicle-epithelium (IFE) and in different epithelial compartments of cortical and medullary zones. Positive reaction for thymostimulin-like (TS-like) substance was restricted to FAE cells and weakly to the basal lamina of IFE. In 6-month-old chickens, the FAE cells disappeared; the phenomenon of bursal regression was evident, although not all the follicles were involved. In the few still normal follicles, the good reactivity to the enzymes tested suggests that residual physiological activity is still present, even if reduced.

The immunomodulating and antimetastatic activity of clinically approved, low molecular weight, standardized thymic peptide (TP) preparations was evaluated in BALB/c-mice. Daily applications (subcutaneously, s.c.; intraperitoneally, i.p.; intramusculary, i.m.) of two commercially available TP preparations (7 consecutive days, 10, 50 and 100 micrograms per mouse and injection) up-regulated the thymus weight and thymocyte counts as well as peripheral blood leukocyte and lymphocyte counts in liver metastases-bearing mice. The immunomodulating activity of TP application was most pronounced and statistically significant for thymus weight and counts of thymocytes, leukocytes and lymphocytes after s.c. administration of both TP preparations and concentrations. I.p. and i.m. TP-injections were less effective at reaching statistical significance, however, for defined dosages and parameters, only. To evaluate the influence of TP on experimental liver metastases, RAW 117 lymphosarcoma cells were intravenously inoculated into BALB/c-mice. TP (10, 50, 100 micrograms/mouse) were s.c., i.p. and i.m. administered daily for 7 consecutive days starting 24 hours after tumor cell challenge. Liver colonization was investigated on day 14 after tumor cell inoculation and demonstrated a statistically significant (p < 0.05) reduction of experimental liver metastases for s.c. (both preparations and concentrations) as well as i.p. and i.m. (dose-dependent) TP-treated mice.

Proliferating cell nuclear Ag (PCNA) occurs as a component of multiprotein complexes during cell proliferation. We found the complexes to react with murine anti-PCNA mAbs, but not with anti-PCNA Abs in lupus sera. The complexes were purified from rabbit thymus extract by affinity chromatography using anti-PCNA mAbs (TOB7, TO17, and TO30) and analyzed by ELISA, immunoprecipitation, immunoblotting, and HPLC gel filtration. That PCNA was complexed with other proteins was demonstrated by its copurification with a group of proteins excluded by an HPLC G3000 SW column. Although immunoblot analysis showed the mAbs to react exclusively with the 34-kDa PCNA polypeptide, they nonetheless immunoprecipitated the same group of proteins, confirming the interaction of the isolated PCNA with other proteins. Anti-PCNA sera, including AK, which reacts with biologically functional sites on PCNA, did not react with complexed PCNA, but did react with it once it was dissociated from the complexes. PCNA complexes in turn reacted with murine anti-DNA mAbs, as well as with Abs against p21, replication protein A, DNA helicase II, cyclin-dependent kinases 4 and 5, and topoisomerase I. These findings suggest that the PCNA complexes purified using anti-PCNA mAbs comprise the "protein machinery" for DNA replication and cell cycle regulation. They also suggest that anti-PCNA mAbs are useful tools with which to characterize the protein-protein interactions within PCNA complexes, as well as the autoimmune responses to proteins interacting with PCNA, which may shed light on the mechanisms of autoantibody production in lupus patients.

Recurrent thrombo-embolic episodes and pregnancy loss, thrombocytopenia and the presence of antiphospholipid antibodies, first described in 1983 by Hughes and defined by Harris in 1987, are characteristic of the primary antiphospholipid syndrome (APS). APS is the cause of obstetrical problems in the form of recurrent miscarriages, intrauterine fetal death or growth retardation, and EPH gestosis. Clinical symptoms described above are probably mediated by antiphospholipid antibodies which interact with endothelial and trophoblastic cells, blood platelets, embryonic tissue cells, as well as with coagulation factors and proteins involved in the coagulation cascade or in antibody binding. Management of APS includes antiaggregation, anticoagulation, immunosuppression, and intravenous administration of gamma globulins. Successful treatment is not always the case and search for more efficient therapies continues. The importance of animal experiments led to the design at the Department of Pathology of Pregnancy and Labour of an APS model in pregnant and nonpregnant rabbits. As Turowski et al. have confirmed the immunomodulating action of TFX in rabbits, it seemed justified to examine the properties of this preparation in pregnant rabbits with experimentally induced APS. The material consisted of 30 pregnant New Zealand rabbits, divided into the following groups: I--10 pregnant rabbits (and 63 fetuses) treated intradermally twice weekly since the 10th day of pregnancy with cardiolipin together with adjuvant; I-K--5 pregnant rabbits (and 17 fetuses) treated with cardiolipin and adjuvant in the same manner as group I and additionally with intramuscular injections of 0.9% NaCl on the 20th, 21st, and 22nd day; I-T--10 pregnant rabbits (and 66 fetuses) treated with cardiolipin with adjuvant in the same manner as group I and additionally with intramuscular injections of 10 mg/day of TFX (Jelfa, Poland) on the 20th, 21st, and 22nd day of pregnancy; K--5 pregnant rabbits (and 27 fetuses) treated with injections of 0.9% NaCl twice weekly. Blood samples for laboratory analysis were collected by cardiac puncture before immunization (sample I) and on the day of caesarean section (sample II). Platelet counts and APTT tests were done. Numbers of live and dead newborns, resorbed fetuses, body mass, newborn viability and survival rates were recorded. TFX administered to pregnant rabbits with experimentally induced antiphospholipid syndrome increased the number of live newborns, reduced the incidence of fetal resorption, increased the viability and survival rate of newborn rabbits. The beneficial effect of TFX on APTT and platelet count was revealed, such that these parameters remained within the normal range despite immunization. Morphological changes observed in the placenta were not specific.

The gene segments encoding the beta chain of the T-cell antigen receptor undergo rearrangement in a precise developmental order: a D beta gene segment joins to a J beta gene segment prior to the rearrangement of a V beta gene segment to join the D/J beta fusion. Current evidence suggests that the rearrangement of V beta is restricted to T cells, whereas D-to-J beta rearrangements may occur in both B and T cells. Thus, the T-cell specificity seems to be regulated by the V beta coding region or its 5' flanking sequence. In support of this hypothesis, evidence is provided for thymus-specific factors that bind a highly conserved 10-base-pair (decamer) sequence that is an essential promoter element in mouse and human V beta genes. The presence of decamer-binding activities was assayed by gel mobility-shift analysis using protein extracts from thymus, spleen, and nonlymphoid organs of adult mice. Two shifted complexes, designated T2 and T3, were seen only when the decamer was incubated with extracts from thymus. When extracts from mice of various gestational ages were tested for decamer-binding activity, one of the thymus-specific complexes, T2, was first detected at day 16; this coincides with the time of initial activation of the V beta locus. No decamer-binding activity was detected in extracts prepared from the thymuses of SCID (severe combined immunodeficiency) mice, which characteristically fail to rearrange these genes. Moreover, neither T2 nor T3 was detectable with extracts from spleen or from two T-cell lines that express the beta chain; this suggests that the presence of these two complexes is not absolutely required for transcription of the T-cell receptor beta locus. We conclude that there are tissue-specific and developmentally regulated factors that form complexes with the decamer sequence 5' of V beta; these may represent initiation factors that control the activation of germ-line T-cell receptor V beta genes for transcription and/or rearrangement.

The localization of three monoclonal (A,B,C) anti-cytokeratin antibodies and of an anti-thymostimulin antibody were studied in normal children's thymuses, aged from 2 months to 10 1/2 years and in Down's children thymuses, aged from 5 months to 6 1/2 years. Two anti-cytokeratins were positive in the thymus: the anti-B was found in the epithelial cells of all thymic zones, the anti-C only in the external cells of Hassall's corpuscles. The distribution and the intensity of immuno-reactions were the same in normal and in Down's thymuses. The distribution of anti-thymostimulin was superimposed to the distribution of anti-cytokeratin B and was similar in normal and in the youngest Down's thymuses, whereas in the 6 1/2 years-old Down's thymuses there was a loss of anti-TS reaction in the subcapsular zone. A relationship between the reduction of anti-thymostimulin immuno-reaction and the beginning of an eventual loss of T-lymphocyte differentiation was supposed.

At concentrations of 25, 50, and 100 microM, capsaicin, which is the major component in various aspects of Capsicum hot peppers, decreased the binding of aflatoxin (AFB1) to calf thymus DNA by 19%, 44%, and 71%, respectively, in incubations with rat liver S9. At concentrations of 50 and 100 microM, capsaicin decreased the formation of AFB-DNA adducts (AFB1-N7-Gua) by 53% and 75% as determined by high-pressure liquid chromatography (HPLC). HPLC analysis of organo-soluble fractions showed that these effects correlated with a concentration-dependent decrease in S9-mediated metabolism of AFB1 by capsaicin. Capsaicin also altered the formation of water-soluble conjugates of AFB1. This was indicated by a decrease in radioactivity in water-soluble fractions and in glutathione conjugates of AFB1 analyzed by HPLC. These results suggest that capsaicin inhibited the biotransformation of AFB1 by modifying Phase I hepatic enzyme activity.

An anti-thymostimulin (TS) serum was tested on rabbit, guinea-pig, lamb and pig thymuses to study the localization of the hormonal factor. The immuno-peroxidase method, with some modifications, was applied to tissue fixed in Bouin's or in Bouin-PAF liquids and embedded in paraffin wax. Immuno-reactivity was shown in reticulo-epithelial cells in the cortex, in the medulla and in the external cells of the Hassall's corpuscles. The intensity of the immuno-reaction is stronger in pig thymus, whereas in lamb, rabbit and guinea-pig thymuses it is more uniform and pale, but to varying degrees. Comparison with the localization of TS in thymuses of other mammals and man and the problem of species-specificity were discussed.

The serum level of a circulating thymic factor (FTS) described in our laboratory diminishes in mice after adult thymectomy and with age. However, thymuses from old mice, when grafted into young adult thymectomized recipients lacking circulating FTS, can still partially restore the circulating FTS level of the recipients, whereas newborn thymuses are less efficient in restoring the serum level of FTS in old recipients than in young adult thymectomized recipients. Taken together, our results suggests that in addition to an intrinsic deficiency of the thymic secretion, "environmental" factors play a role in the disappearance of circulating FTS with age, the more so since we observed in old mouse sera factors inhibiting the in vitro biologic activity of FTS, factors that are absent from young mouse sera.

An anti- thymostimulin (TS) serum was tested on calf thymus to study the localization of the hormonal factor. The immunoperoxidase method was applied to tissue fixed in Bouin's fluid and embedded in paraffin, or to tissue fixed in paraformaldehyde and embedded in Epon for semi-thin sections. Immuno-reactivity was shown, with DAB- Fluka , in reticulo-epithelial cells in the medulla, and between the cortex and the medulla, while with DAB-Sigma reactivity was found in the cortex as well. The external cells of Hassall's corpuscles were also reactive. Myoid cells were not reactive. In semi-thin sections a weak reactivity was noted at the periphery of a few lymphocytes. Comparison with the localization of other thymic factors, and the possibility of a functional cycle of the epithelial cells synthesizing one or more factors are discussed.

Thymomodulin (Leucotrofina), an orally administrable thymic derivative endowed with interesting immunomodulating and myelomodulating properties, was tested for mutagenicity by means of the following in vitro and in vivo tests: mutagenesis on S. typhimurium with and without metabolic activation system (S-9), gene conversion on S. cerevisiae D 7 with and without metabolic activation, urinary assay in the mouse with and without metabolic activation, urinary assay in the mouse with S. cerevisiae D 7, host mediated assay in the mouse with S. cerevisiae and DNA repair test with and without metabolic activation. On the basis of the results obtained thymomodulin proved to be free of mutagenic activity.

As a first step toward improving dideoxynucleoside inhibition of human immunodeficiency virus replication in human lymphocytes, we examined the kinetics of 5'-phosphorylation of a series of 2',3'-dideoxynucleosides, using deoxycytidine kinase purified from human thymus extracts. Nucleosides with the 2'-deoxyribose moiety were activated 30 times faster than were 2',3'-dideoxynucleosides. The adenosine deaminase inhibitor, 2'-deoxycoformycin, showed an unexpected ability to inhibit purine and pyrimidine dideoxynucleoside phosphorylation; such inhibition was not competitive and was not observed when 2'-deoxycytidine was the substrate. 2'-Deoxycytidine, the natural substrate, inhibited dideoxynucleoside phosphorylation in a manner similar to that observed with 2'-deoxycoformycin. Thus, dideoxynucleosides are activated by deoxycytidine kinase through a different catalytic interaction than occurs in 5'-activation of 3'-hydroxynucleosides by this enzyme.

The covalent binding of 14C-1,1,2-trichloroethylene (14C-TRI) metabolites to calf thymus DNA in vitro and to RNA and DNA of mouse brain, lung, liver, kidney, spleen, pancreas, and testis after repeated i.p. injections has been studied. Hydrolysates of DNA reacted with 14C-TRI in vitro and hydrolysates of RNA and DNA from selected organs were separated on Aminex A6 for quantitation of alkylation products. The presence of 3,N4-etheno(deoxy)cytidine, 1,N6-etheno(deoxy)adenosine and 1,N6-ethenoadenine was investigated. No radioactivity could be registered in DNA incubated with 14C-TRI in the absence of liver microsomes. Covalent binding of 14C-TRI to DNA took place in the presence of liver microsomes from control mice. The binding was enhanced by 50% if liver microsomes from phenobarbital pretreated mice were used. The radioactivity in DNA reacted with 14C-TRI and microsomes from control mice was eluted in early fractions and together with thymidine. The same two peaks appeared on chromatography of DNA incubated with 14C-TRI and liver microsomes from phenobarbital pretreated mice. In addition, radioactivity was eluted together with 1,N6-ethenoadenine. Radioactivity was registered in RNA and DNA from all of the studied organs after i.p. injections of 14C-TRI. The radioactivity in RNA increased in the order brain less than testis less than pancreas less than kidney less than liver less than lung less than spleen. The radioactivity in DNA increased in the order brain less than kidney less than testis less than lung less than pancreas less than liver less than spleen. Aminex A6 chromatography revealed that the entire radioactivity in RNA from liver and kidney and in DNA from kidney, testis, lung, pancreas, and spleen was due to metabolic incorporation, particularly into guanine and adenine. This finding indicates that the C-C bond in TRI is split, with the formation of C1-fragments, during biotransformation in vivo. In liver DNA, the metabolic incorporation of radioactivity was insignificant. Instead, the dominant part of the radioactivity in liver DNA was eluted in early fractions. The elution profile of radioactivity in liver DNA gave no direct evidence of the formation of TRI-DNA adducts in vivo. No etheno-derivatives were identified as alkylation products of TRI in vivo, which is consistent with current theories of the metabolic fate of TRI.

Anti-bovine thymostimulin serum reacts with reticulo-epithelial cells in the cortex and in the medulla of rat and mouse thymuses. The immuno-reaction is present in a smaller number of cells which have more pallid color than those found in calf thymus. Comparative examination as to the distribution of other thymic factors and as to species-specificity was conducted.

New Zealand Black (NZB) mice develop after 16 weeks of age an autoimmune and lymphoproliferative disease which is a model for systemic lupus erythematosus and lymphoid malignancy in humans. At this age, the mice manifest a progressive decline in T lymphocyte (thymus-derived lymphocyte) functions and serum thymosin levels. Thymocytes from 8-week old NZB mice exhibit an abnormal DNA synthetic response when transplanted into lethally irradiated C57B1/6 recipients. DNA synthesis (measured as the incorporation of radioactively labeled 5-iodo-2'-deoxyuridine) is delayed in onset and still increasing 6 days after cell transfer. By contrast, 2-week old NZB thymocytes show a normal response which is rapid in onset and completed by day 6.NZB mice were injected with thymosin fraction 5 or with bovine serum albumin starting at 2 weeks of age. Thymocytes from 8-week old thymosin-treated mice showed a normal DNA synthetic response, whereas the albumin-treated controls showed the abnormal response expected at this age. The ability of thymosin to correct the DNA synthetic response was related to dose and duration of treatment. These results suggest that thymosin can induce a more normal state of thymocyte differentiation in NZB mice. If abnormal thymocyte differentiation is related to the subsequent emergence of autoimmunity and lymphoid malignancy, then continuous treatment with thymosin may have therapeutic potential. These experiments suggest that an endocrine disturbance may contribute to autoimmune and lymphoproliferative disease in NZB mice and possibly in humans.