Environmental lead exposure and its relationship to traffic density among Senegalese children: a pilot study

In Senegal, as in many developing countries, traffic density is increasing in urban areas; in Dakar more than 50% of vehicles use gasoline. Yet the extent and real magnitude of the problem has neither been recognized nor assessed in these countries. Systemic data assessment of lead pollution and people's exposure are not well known in Senegal. This study was also designed to determine the impregnation levels of the lead released by the exhaust of cars and the changes of some early biological markers in Senegalese children. Blood lead (BPb) levels showed that all the children enrolled were exposed. However, lead exposure levels (from 34.7 to 145.8 mg/L) were less important for children living in rural areas (60.99-18.3 mg/L) than for those living in urban areas (106.79-16.9 mg/L). These changes could be correlated to the difference in the automobile traffic between both these regions (P B-0.001). BPb mean levels found in boys were higher than those in girls (P B-0.05). Despite elevated BPb levels, all values for blood zinc protoporphyrin and urine delta-aminolevulinic acid were within physiological ranges. In addition, variations in some biological markers of oxidative stress and renal disorders were seen; however, they must be confirmed by a future epidemiological study.

Environmental lead exposure and its relationship to traffic density among Senegalese children: a cross-sectional study

Leaded-gasoline is probably the primary source of lead (Pb) exposure in Dakar (Senegal). The present cross sectional study was undertaken to investigate the levels of Pb in Senegalese children and to present helpful data on the relationship between Pb levels and changes in biological markers of heme biosynthesis and oxidative stress. A total of 330 children, living since birth either in rural or urban areas (ie, Khombole (n=162) and Dakar (n=168), respectively) were included. During this cross sectional study, the mean blood (B)-Pb level in all children was 7.32±5.33 ųg/dL, and was influenced by the area of residence and gender. In rural children, 27 subjects (16.7%), 18 boys (19.6%) and nine girls (12.9%), had a B-Pb level >10 ųg Pb/dL, whereas 99 urban children (58.9%), respectively, 66 boys (71.8%) and 33 girls (43.4%), had alarmingly high B-Pb levels. Accordingly, urine delta-aminolevulinic acid levels were higher in children living in the urban area than in the rural areas (P B±0.001), and closely correlated with the B-Pb levels (P B±0.01). Moreover, glutathione peroxidase (GPx) activity, selenium (Se) level, glutathione reductase (GR) activity, and glutathione status were significantly influenced by area of residence and/or by gender. GPx activity and Se level were not only negatively correlated with B-Pb levels, but also positively correlated together (P B±0.01). Taken together, the present results allow us to conclude that urban children have higher B-Pb levels than rural children, and that of these children, boys have higher B-Pb levels than girls, leading thereby to alterations of heme biosynthesis and pro-oxidant/antioxidant balance. We also suggest that exposure to Pb and the Pb-induced adverse effects merits attention and that the development of preventive actions are of increasing importance in Senegal.

Downregulation of CD94/NKG2A inhibitory receptor on decreased γδ T cells in patients with systemic lupus erythematosus

γδ T cells are characterized by recognizing conserved endogenous and stress-induced antigens without antigen presentation. It has been show that γδ T cells play an important role in anti-tumour/microbe responses, but their function in autoimmune diseases is yet not clear. Here, we reported the quantity and phenotype of peripheral blood γδ T cells from systemic lupus erythematosus (SLE). Both the percentages of γδ T cells in peripheral blood and among CD3(+) T cells of patients with SLE were significantly decreased, regardless of disease activity. However, activating marker CD69 and HLA-DR was upregulated, while inhibiting receptor CD94/NKG2A was downregulated in γδ T cells of patients with SLE. The expression of CD69 is negatively correlated with the quantity of γδ T cells. Moreover, the expression of CD94/NKG2A remained low even with antigen stimulation on those γδ T cells. Our results suggested that the low expression level of CD94/NKG2A upon γδ T cell activation might lead to the over-activation of γδ T cells in patients with SLE. These findings will be useful in elucidating the roles of γδ T cells in SLE pathogenesis.

[Quality of butter sold in Dakar (Sénégal)]

Among foods that are introduced in Senegal, butter takes a significant place particularly at home where it is frequently eaten. Nevertheless, Senegalese authorities don't carry out any quality control under those different types (mark) of butter. In consequence, to find butter without quality or characteristics of authentic butter may be high. The aim of this work is to analyse quality of main varieties of butter in Dakar market. Chemical methods were used to determine the characteristic of butter samples and gas chromatography was made to authentify their fatty acid profile. Our results have shown that most of analysed sample respected the standards of quality. In fact the composition of fatty acid and characteristic factors of authentic butter were certified by this study.

[Antiparasitic effect of Senegalese Annonaceae used in traditional medicine]

Annonaceae is a large family of plants widely used in alimentation and traditional medicine. The interest of their study is raised up by the presence of biologically active substances among that the acetogenins which are specific to them. In Senegal, three species are widely used in traditional medicine for various indications and particularly in parasitic diseases: Annona senegalensis, Uvaria chamae and Xylopia aethiopica. The study of antiparasitical extracts from various organs showed an interesting activity of the fruits and leaves of Xylopia aethiopica on Leishmania donovani, the stem barks and roots of Uvaria chamae on Trypanosomia brucei and the roots of Annona senegalensis on the chloroquino-resistant strain of Plasmodium falciparum. Bioguided fractionation of the active extracts led to isolate Annonaceous acetogenins. Therefore, thirteen acetogenins, from the roots of Uvaria chamae and Annona senegalensis, were identified. The presence of acetogenins, substances with antiparasitical activity, could partly explain the biological proprieties of these various drugs.

[Aflatoxins in food: tests of decontamination of peanut cakes by ionizing treatment]

The efficacy of ionising treatment for decontaminating peanut cakes was tested. The influence of cakes water content and the effect of ionisation dose rate were studied. The results obtained after a reverse phase liquid chromatographic determination of B1, B2, G1 and G2 aflatoxins have revealed an important contamination of the peanut cakes (up to 1000 ppb of total aflatoxin's contents). After ionising treatment at 25 kGy, the aflatoxins degradation in peanut cake's was less important in dried samples (about 5-10% at 0.55 water activity: aw) than in the humid ones (40-60% degradation at 0.95 water activity). At this dose, any indicative difference of the degradation rate of aflatoxins, with regard to the ionising process was observed. The efficacy of ionising treatment for decontaminating peanut cakes could probably be improved, however the economic interest of such process as alternative of the treatment with ammonia is questionable.

[Pesticide bioaccumulation: measurement and levels of organochlorine residues in products of vegetable origin]

Because of their lipophilic properties and their persistence, organochlorine pesticides residues can be accumulated in human body by consuming regularly plants products. This study consisted of the monitoring of the contamination level of pesticides residues from various plants products, in order to assess the long- term intoxication risk to which Senegalese consumer is exposed ant identify throughout these plants some indicators of atmospheric pollution. The chromatographic analysis of medicinal plants, fruits and vegetables extracts showed that they could be contaminated by organochlorine residues. About ten of these pesticides residues were found confirming that the analysed plants were really contaminated. The residues level in medicinal plants (from 0.1 to 45 micrograms/kg) were widely below the maximum allowed concentrations and were also lower than those in fruits and vegetables (from 0.1 microgram/kg to 460 micrograms/kg). Heptachlorine residues contents of tomatoes and citrus fruits were higher than FAO/WHO norms, so that, a regular monitoring of the plants products is recommended for better protection of consumers.

Antitumor activity of expanded human tumor-infiltrating gammadelta T lymphocytes

BACKGROUND

The objective of this study was to investigate the antitumor activity of selectively expanded gammadelta T cells in tumor-infiltrating lymphocytes (gammadeltaTILs) or tumor ascites lymphocytes (gammadeltaTALs) from patients with colorectal and ovarian epithelial carcinoma (OEC) in vitro and in vivo.

METHODS

gammadeltaTILs/TALs were expanded by the solid-phase antibody method; their cytolytic and proliferative activities in vitro were detected by the MTT method and 3H-TdR incorporation and their effect in vivo was evaluated by the nude mice model.

RESULTS

Expanded gammadeltaTILs from colorectal tumors demonstrated marked cytotoxicities to allogeneic human colon adenocarcinoma HR8348 and lymphoma Daudi cells, as well as xenogeneic murine thymoma EL-4 cell lines. Cytokines, including IL-2, IL-4, IL-12, IL-15, TNF-alpha and INF-gamma, could promote the cytotoxicities of gammadeltaTILs to tumor cells, whereas IL-10, GM-CSF and TFG-beta had no effect on such killing activities. Rested gammadeltaTILs could proliferate strongly in response to mitomycin C-treated Daudi and EL-4 tumor cells, but not to HR8348 tumor cells, suggesting that the latter might possess only cytotoxicity-related antigen recognized by gammadeltaTILs. Either alphabetaTILs or gammadeltaTILs from patients with OEC displayed cytotoxicities to allogeneic or autologous OEC cell lines at a similar strength in vitro. Transferring gammadeltaTILs into Daudi cell-bearing BALB/c nude mice with an injection of IL-2 was able to maintain a high survival rate of the mice for 30 days, when compared with mice treated with alphabetaTILs or without any treatment (p < 0.05). Without coinjection of IL-2, after 3 months of Daudi tumor inoculation, a high survival rate was observed in gammadeltaTIL-treated mice. Similarly, adoptive gammadeltaTALs from the ascites of patients with OEC transferred into nude mice displayed a stronger antitumor response to OEC SKOV3 cells than alphabetaTALs in vivo. Tumor volumes in gammadeltaTAL-treated mice were smaller than in alphabetaTAL-treated or non-TAL-treated mice within the period from day 23 to day 50 after tumor inoculation (p < 0.05). Fifty days after SKOV3 tumor inoculation, a decreasing trend of carcinogenic rate was observed in gammadeltaTAL-treated nude mice.

CONCLUSION

Taken together, our results suggest that gammadeltaT cells could be a new candidate for adoptive immunotherapy in the future treatment of patients with cancer.

[Contamination by aflatoxins of local peanut oils prepared in Senegal]

Aflatoxins are mycotoxins produced by certain strains of fungus (Aspergillus) which develop in peanut seeds. Peanut oil and peanut meal are widely used in Senegal. The risk of intoxication is quite real. We determined aflatoxin contamination levels in peanut oil and food prepared by small scale production plants in the Kaolack and Diourbel regions of Senegal. High performance liquid chromatography (HPLC) of the different samples showed that 80% of them were contaminated. Aflatoxin B(1), B(2), G(1) and G(2) were detected. The pattern of contamination was similar for the two regions. Aflatoxin B(1) was prevalent and found in over 85% of the samples. The mean content of this mycotoxin (the most dangerous toxin) was about 40 ppb, a value which largely exceeds specifications for allowable levels.

[Well water pollution in the Khombole district: research on the contamination by organochlorine pesticide residues and organic substances (feces)]

The study realized in the district of Khombole (SENEGAL) has permit to estimate the contamination levels of wells waters used by the populations. The research and the dosage of the organichlorine pesticide residues, nitrites and nitrates and microbiologic analysis have been done on 19 wells chosen after a drawning of lots. The organochlorine pesticide residues which have been found prove that the wells are permanently exposed to these chemical substances which don't constitute nevertheless a major risk for the populations health. The results of our research proved also that there is a real risk of intoxication with the nitrogen oxides. In effects more than 50% of the wells have revealed nitrates contents up to the indicative value (25 mg/l). As for the nitrates, with a few exceptions (5/18), the contents are superior to the authorized norm (0.1 mg/l). By another way the bacteriologic analysis has revealed in the one hand a DBT (Total Bacterian Count) up to 10,000 germs/l for all the wells, and in the other hand the presence of Escherichia coli, Enterococcus faecalis that confirm a faecal contamination.

[Aflatoxin contamination level in artisanal and industrial peanut butter food in Dakar (Senegal)]

Aflatoxins are mycotoxins produced by some strains of fungus (Aspergillus) which develop in peanut seeds. Peanut oil and past are very used up in Senegal, then the aflatoxin poisoning risk is very actual. The aim of this study was to determinate the aflatoxin level in artisanal and industrial peanut pastry food from Dakar (Sénégal). High Performance Liquid Chromatography (HPLC) analysis of the different samples showed that the most contaminated by aflatoxins are artisanal pastry sold in different market of Dakar (Sénégal). Indeed, 40% of these samples contained mean values of aflatoxin B1 (the most dangerous) widely over allowable EEC specifications (5ppb). Furthermore, most of industrial and domestic peanut pastry were cleaned and could be consumed without risk.

[Mango leaves (Manguifera indica, Anacardiacea) used as biomarker of pollution by pp'Dichlorodiphenyltrichloroethane (pp'DDT)]

Dichlorodiphenyltrichloroethane (DDT), organochlorine pesticide, byanother way cumulative pesticide is banned in mostdeveloped countries. Whatever, it is still used in many countries in the Third World. This work consist to check whether this chemical compound is still used in Senegal. The biomarker of pollution by this pesticide for this research was mango leaves (mango tree is widespread in Senegal) open to accumulate halogenated hydrocarbons. Leaves sample were taken in many sites in the centerline of Dakar-Thiès (Senegal), then analysed by gas chromatography. The results allowed to note the presence of DDT and its metabolites [(dichlorodiphenyltrichloroethylen (DDE), (dichlorodiphenyltrichloroethane (DDD)] in most of samples. The comparison of DDT content in relation to those of the principal metabolite allowed to make the difference according to sample sites, an old contamination of an utilisation more or less recent of this pesticide. From those results, we can conclude that DDT, typical pesticide by its big persistence is still used in some spherical zones in this country, in particular in farming gardening zones.

[Air pollution by lead emitted from vehichles in the Dakar region]

The use of super carburant involves a lot of lead particles by the vehicles. This type of pollution specially affects the urban populations and the environment. This phenomenon is emphasized in the big cities like Dakar where more than 60% of the national car park move. This study shows that the trees can be used as indicator of lead pollution level. Unfortunately, the estimation of the pollution level isn't always easy whereas numerous factors can play a role in the mechanism. In this study, we have shown that the atmospheric pollution of Dakar by the muffler gases is a real fact.

[Construction of eukaryotic vector for human interleukin-15 cDNA and its expression in lung carcinoma cell lines]

OBJECTIVE

Human interleukin(hIL)-15 expression of lung cancer cell lines transfected by rhIL-15 cDNA in vitro was observed.

METHODS

The recombinant plasmid pL-IL-15-SN was established by inserting IL-15 cDNA into vector pLXSN at sites of EcoR I and BamH I. The pL-IL-15-SN was transfected into human lung squmosuse carcinoma (PG) cell line and murine lung adenocarcinoma (LA795) cell line, respectively. Positive clones were obtained by the selection in G418 conditioned culture. Bioactivity on rIL-15 was detected by dependant-proliferation of CTLL-2 cells in vitro.

RESULTS

Three positive PG and four positive LA795 cell clones were obtained respectively. The results of the assays for hIL-15 bioactivity showed that the expression levels of rhIL-15 ranged from 142 to 201 or from 138 to 178U/(ml.10(6)) for positive PG cells or LA795 cells, respectively.

CONCLUSIONS

Human and murine lung carcinoma cells transfected with IL-15 cDNA can express hIL-15 with bioactivity.

[Efficient, stable expression of human interleukin-15 cDNA in Chinese hamster oval cells]

OBJECTIVE

To express the human interleukin 15(IL-15) cDNA in Chinese hamster oval (CHO) cells, which would benefit to the further research in the biological activities and the clinical applications of IL-15.

METHODS

The entire human interleukin-15(IL-15) coding region, deleted of all the uncoding fragments, was amplified by PCR. The amplified products were subcloned into the EcoR I and Xba I sites of the pcDNA3 plasmid, forming the recombinant eukaryotic expressing vector, pcDNA3-IL-15, which was then identified by the Bg1 II enzymatic digestion, PCR amplification and the sequence analysis. The construct was transfected into CHO cells by means of lipofectamine, followed by a series of determinations to screen the positive cell colonies, such as RT-PCR, SDS-PAGE, ELISA and CTLL-2 proliferation assay.

RESULTS

8 positive cell colonies highly expressed human IL-15 were obtained after G418 selection. The bioassay showed that the mean activities of the supernatants from the CHO-IL-15 cells were (318.54 +/- 32.76) U/(10(6) cells.d) and maintained stable after 6 months culture.

CONCLUSIONS

Human IL-15 cDNA was expressed efficiently and persistently in CHO cells.

Expansion and immunological study of human tumor infiltrating gamma/delta T lymphocytes in vitro

Goffa/delta T cells have stimulated a lot of interest because of their unique features in antigen recognition and cytotoxicities to many autologous and/or allogeneic tumor cells. We have developed a novel method to selectively expand larger amounts of human tumor-infiltrating gamma/delta T lymphocytes (gamma/delta TILs) ex vivo by immobilized pan- anti-TCRgamma/delta monoclonal antibody in the presence of exogenous IL-2. The expanded gamma/delta TILs mainly expressed CD45RO and HLA-DR molecules and did not express CD4. CD8+ gamma/delta TILs accounted for 19% of gamma/delta TILs. The expression of CD25 molecule on expanded gamma/delta T cells was inducible and downregulated following a time course. The Vdelta1 and Vdelta2 subsets amount to 37 and 58%, respectively. The expanded gamma/delta TILs show an IL-2-dependent proliferation, MHC class I-unrestricted and TCRgamma/delta-related cytotoxicities to two MHC class I+ and two MHC class I+ allogeneic tumor cell lines in vitro.

[Measurement and levels of aflatoxins in small-scale pressed peanut oil prepared in the Diourbel and Kaolack regions of Senegal]

Aflatoxins are mycotoxins produced by some strains of fungus (Aspergillus) which develops in peanuts seeds. Peanuts oil and past are very used up in Senegal, then the aflatoxins poisoning risk are very actual. This study relates to the determination of contamination levels by aflatoxins from peanut oil food prepared by small scale production in areas of Kaolack and Diourbel. High Performance Liquid Chromatography (HPLC) analysis of the different samples showed that 80% of them were contaminated in the areas of Kaolack and Diourbel. Aflatoxin B1, B2, G1 and G2 has been detected with a profile of contamination almost identical in the both areas. Aflatoxin B1 was prevalent and has been found in over 85% of samples. Mean contents of this mycotoxin (the most dangerous toxin) is about 40 ppb, value widely superior to allowable specifications.

[Recombinant human GM-CSF retroviral vector construction and expression in human breast cancer cells]

OBJECTIVE

To provide an effective GM-CSF gene transferring vector mediated by retrovirus and a basis for study of GM-CSF gene-modified tumor cell vaccines.

METHODS

The recombinant retroviral vector pDORGM was constructed by cloning the GM-CSF cDNA into the replication defective retroviral vector pDORneo, and transferred into packaging cell line PA317 by Lipofectin method. The viral titer was determined with the NIH3T3. Using the NIH3T3 amplification assay, replication competent retroviral particles were detected. A high titer of retrovirus was used to infect the human breast cancer cell line MCF-7.

RESULTS

The retrovirus containing GM-CSF gene had a highest titer of virus of 1 x 10(6) colony-forming units/ml. No replication competent retrovirus were detectable in the vector preparation from the packaging cells. GM-CSF gene-modified MCF-7 cell lines stably released 500 to 800 units/10(6) cell of GM-CSF within 24h in vitro.

CONCLUSION

The GM-CSF gene transferring vector mediated by retrovirus was effective and safe. These results provied a basis for study of GM-CSF gene used in cancer gene therapy.

Treatment of 121 patients with malignant effusion due to advanced lung cancer by intrapleural transfer of autologous or allogeneic LAK cells combined with rIL-2

Lymphocytes isolated from malignant pleural effusion in patients with advanced lung cancer or from allogeneic peripheral blood of healthy donors were induced to become LAK cells after in vitro culture with rIL-2. One hundred and twenty-one patients with malignant effusions were treated by intrapleural transfer of autologous or allogeneic LAK cells combined with rIL-2. The effusion disappeared in 71 patients (58.6%) and was significantly decreased in 45 patients (36.2%). Five patients did not respond to treatment. Tumor cells in pleural effusions disappeared or were significantly decreased in number, whereas the lymphocytes were significantly increased in number in all responders. Except for transient fever in 10 patients, no serious side effect was observed.

[Drug prescription in Dakar and outskirts]

Drugs are very important to human life due to their human mission and to the essential role they play in modern society through their real social function. When used in certain conditions, drugs are expensive, ineffective and can even become dangerous and the source of poisoning with serious consequences. In order to minimize risks and accidents, special attention is paid to drugs from their conception to their elimination by the body, resulting inter alia in a severe control of their prescription. In Dakar, where are can find the greatest number of prescribers in Senegal, this control is rarely respected. This situation can be fraught with serious consequences for the health of populations.

[Surveillance of heavy metal pollution of mangrove oysters in Senegal]

Joal-Fadiouth, located in department of Mbour (region of Thies), 118 kilometers from Dakar, the capital of Senegal, is an area where one can find a large swamp with mangroves whose self-propagating roots serve as growth support for young oysters. The importance of those oysters, both on the domestic and foreign markets and the ever greater threat of pollution of our coasts led us to search for and measure out heavy metals. In fact, it is well know that the accumulation of those elements in the food chain can be at the origin of severe poisoning. It appears, in the light of the results obtained that the level of pollution by heavy metals in this part of the senegalese coast has not yet reached alarming limits.

The arrest of T cell maturation in spontaneously hypertensive rats with a deficient production of thymic factors

Spontaneously hypertensive rats (SHR) which regularly develop hypertension and periarteritis nodosa showed a progressive loss of T cell numbers and functions early in life. When six months old and compared with W rats, the original strain of SHR, they were found to possess a reduced number of thymocytes that formed rosettes with guinea pig erythrocytes and that reacted to anti-Thy1. 1 and anti-T (W3/13) sera. The number of spleen and lymph node cells which reacted to anti-T (W3/13) and anti-helper T (W3/25) sera also decreased. The antibody response of 3-month-old SHR spleen cells to SRBC was about one-fifth that of Wistar rats and progressively declined with age. Subcutaneous grafting of 3-month-old SHR thymus tissues failed to promote differentiation and functions of T cells in the spleen of nude mice, whereas 3-month-old W thymus tissues showed significant recovery of T cell generation and functions. The T cell functions of old SHR was completely restored by grafting adult W thymus tissues but was not restored by grafting adult SHR thymus tissues. Similar recovery was also obtained by the injection of thymus extracts from W thymus tissues. These results suggest that thymic epithelial cell products regulating T cell maturation may decrease in SHR with increasing age.

Screening of various immunopotentiators in spontaneously hypertensive rats with T-cell depression

A strain of SHR which develops hypertension spontaneously is marked by a selective depression of T-cell functions associated with an early appearance of natural thymocytotoxic autoantibody and a deficiency of thymic hormone. Present results demonstrate that various immunopotentiators (IPs) such as thymostimulin (TS), PS-K, SPG, neurotropin (NSP), and K-247 partially or almost completely reversed the T-cell depression in these SHR as detected by a rosette forming test, plaque-forming assay and blastogenesic response to PHA and Con A. In contrast, these IPs had no effect on the immune responsiveness of WKA rats with normal T-cell functions. Among the IPs, NSP, which had an almost complete restorative effect on the T-cell functions of SHR, induced significant transplantation resistance to the syngeneic tumor challenge. A new synthetic product K-247 also induced a significant suppression of lethal tumor growth in SHR, though its restorative effect on T-cell functions was weak. The fact that K-247 had a suppressive effect on tumor cell growth in vitro indicates that biochemical modifications rather than immunological ones may be involved. However, none of the IPs induced antitumor resistance in normal WKA rats. These results suggest that this strain of SHR provides a useful animal model for evaluation of various IPs.

Immunologic suppression of carcinogenesis in spontaneously hypertensive rats (SHR) with T cell depression

A strain of spontaneously hypertensive rats (SHR) showed a selective depression of T cell functions brought about by aging. Conversely, this strain had a high NK cell activity as compared to other normal rat strains. This SHR strain was found to be much more sensitive to the carcinogenic activity of low doses of MCA than were WKA rats with normal T cell functions. Allogeneic thymus grafts almost completely restored the T cell functions of SHR, whereas injection of an immunopotentiator, NSP, enhanced NK cell activity and also caused a partial recovering of T cell functions. When immunologic restoration was achieved, generation of killer T cells to syngeneic SMT-5 tumor cells was induced and the cytotoxic activity of NK cells to K-562 cells was also enhanced. But the cytotoxic activity to the SMT-5 cells of NK cells and macrophages from the treated or untreated SHR was not detected. Allogeneic thymus grafts induced a significant transplantation resistance against a syngeneic SMT-5 tumor and injection of NSP enhanced only the survival days of the rats. Allogeneic thymus grafts also significantly suppressed the incidence of tumors induced by MCA, whereas the injection of NSP was not effective in the prevention of tumor development but was effective in prolongation of latency periods. These results support the hypothesis that immune surveillance mediated by T cells is an important mechanism for the control of tumor development.

Immunologic suppression of carcinogenesis in spontaneously hypertensive rats (SHR) with T cell depression

A strain of spontaneously hypertensive rats (SHR) showed a selective depression of T cell functions brought about by aging. Conversely, this strain had a high NK cell activity as compared to other normal rat strains. This SHR strain was found to be much more sensitive to the carcinogenic activity of low doses of MCA than were WKA rats with normal T cell functions. Allogeneic thymus grafts almost completely restored the T cell functions of SHR, whereas injection of an immunopotentiator, NSP, enhanced NK cell activity and also caused a partial recovering of T cell functions. When immunologic restoration was achieved, generation of killer T cells to syngeneic SMT-5 tumor cells was induced and the cytotoxic activity of NK cells to K-562 cells was also enhanced. But the cytotoxic activity to the SMT-5 cells of NK cells and macrophages from the treated or untreated SHR was not detected. Allogeneic thymus grafts induced a significant transplantation resistance against a syngeneic SMT-5 tumor and injection of NSP enhanced only the survival days of the rats. Allogeneic thymus grafts also significantly suppressed the incidence of tumors induced by MCA, whereas the injection of NSP was not effective in the prevention of tumor development but was effective in prolongation of latency periods. These results support the hypothesis that immune surveillance mediated by T cells is an important mechanism for the control of tumor development.

Restoration of T cell depression and suppression of blood pressure in spontaneously hypertensive rats (SHR) by thymus grafts or thymus extracts

Spontaneously hypertensive rats (SHR) that develop hypertension and arterial lesions resembling human periarteritis nodosa were found to possess a selective depression of T cell functions with an appearance of natural thymocytotoxic autoantibody (NTA). The relationship between T cell depression and hypertension in these animals was investigated. The immune responsiveness of T cell-depressed SHR was completely recovered by histocompatible thymus grafts and was partially restored by histoincompatible allogeneic or xenogeneic thymus grafts or by injection of thymus extracts. Transplantation of compatible thymus tissues into neonatal SHR produced long-lasting recovery of immune functions. When complete immunologic restoration was achieved, significant suppression of high blood pressure was obtained. The SHR that showed high blood pressure were always accompanied with high NTA titers and arterial lesions. Thymus grafts or thymus extracts significantly decreased the titers of NTA. The development and dissemination of arterial lesions, which may cause increased blood flow resistance, were completely prevented by compatible thymus grafts into neonatal SHR. These results suggest that thymus grafts and thymus extracts may suppress the development of hypertension by preventing or curing the periarteritis nodosa in SHR.

Restoration of T cell depression and suppression of blood pressure in spontaneously hypertensive rats (SHR) by thymus grafts or thymus extracts

Spontaneously hypertensive rats (SHR) that develop hypertension and arterial lesions resembling human periarteritis nodosa were found to possess a selective depression of T cell functions with an appearance of natural thymocytotoxic autoantibody (NTA). The relationship between T cell depression and hypertension in these animals was investigated. The immune responsiveness of T cell-depressed SHR was completely recovered by histocompatible thymus grafts and was partially restored by histoincompatible allogeneic or xenogeneic thymus grafts or by injection of thymus extracts. Transplantation of compatible thymus tissues into neonatal SHR produced long-lasting recovery of immune functions. When complete immunologic restoration was achieved, significant suppression of high blood pressure was obtained. The SHR that showed high blood pressure were always accompanied with high NTA titers and arterial lesions. Thymus grafts or thymus extracts significantly decreased the titers of NTA. The development and dissemination of arterial lesions, which may cause increased blood flow resistance, were completely prevented by compatible thymus grafts into neonatal SHR. These results suggest that thymus grafts and thymus extracts may suppress the development of hypertension by preventing or curing the periarteritis nodosa in SHR.

[Immunological suppression of carcinogenesis in spontaneously hypertensive rats (SHR) with T-cell depression (author's transl)]

We have reported that a strain of SHR have a selective depression of T-cell functions by aging, which may be due to an early appearance of natural thymocytotoxic autoantibody and a deficiency of thymic hormone. Results presented here showed that the tumor incidence in SHR by low doses of MCA was higher than those in WKA rats with normal T-cell functions. Depression of T-cell functions in SHR could be almost completely restored by allogeneic thymus grafts or injection of extracts from vaccinia virus-infected skin tissues (NSP). When immunological restoration was achieved, generation of killer T-cells against syngeneic tumor cells in SHR was induced and activity of NK cells against K-562 cells was significantly enhanced. Effect of thymus grafts or NSP on MCA-induced primary tumors in SHR was studied. Effect of thymus grafts or NSP on MCA-induced primary tumors in SHR was studied. The tumor incidence was significantly suppressed and average latent periods were also prolonged in SHR grafted with allogeneic thymus. The administration of NSP was not effective on tumor incidence but prolonged latent periods for developments of tumors. From these results, it is suggested that the SHR is a suitable animal model for investigation of role of cell-mediated immunity in carcinogenesis.

[Immunological analysis of immunopotentiators in spontaneously hypertensive rats with T-cell depression (author's transl)]

A strain of spontaneously hypertensive rats (SHR) had a selective depression of T-cell functions associated with an early appearance of natural thymocytotoxic autoantibody and a deficiency of thymic hormone. In this paper, the ability of immunopotentiators (IPs) to restore immune functions and to induce antitumor resistance in the T-cell depressed SHR is investigated. In addition, the effect of IPs on activities of natural killer (NK) cells and macrophages is also studied. The results indicate that administration of SPG or Lysozyme enhanced T-cell functions as detected by the rosette formation test and blastogenic responses to PHA. None of the IPs used promoted NK cell activity but Lysozyme and PS-K rather suppressed. In contrast, all IPs used had a effect on activation of macrophages and especially PS-K showed strong activating effect. Following survival and tumor rejection in SHR transplanted with a syngeneic tumor after treatment with the IPs, treatment with SPG produced significant prolongation of survival days but the remaining two IPs had no effect. We propose that the SHR is a suitable animal for quantitative evaluation of the IPs in inducing T-cell mediated immunity an antitumor immune responses.

[Restoration of immune functions in T-cell depressed spontaneously hypertensive rats (SHR) by injection of neurotropin (author's transl)]

A strain of spontaneously hypertensive rats (SHR) showed a progressive decline in T-cell functions with aging. In order to restore the depressed immune functions, the effect of immunopotentiators such as Neurotropin, PS-K or thymus extract on immune responses of SHR was studied. The results presented here demonstrated that injection of Neurotropin completely restored the T-cell functions in SHR as detected by a rosette forming test, a plaque forming assay and blastogenesis. Administration of thymus extract also restored the immune functions except helper T-cell activity. However, administration of PS-K increased only numbers of rosetting cells in the thymus of SHR. Biological significance of Neurotropin as immunopotentiators was discussed.

[Lipolysis and aflatoxin production in Aspergillus flavus (author's transl)]

Lipolysis in relation to toxinogenesis has been studied in various strains of Aspergillus flavus. Toxinogenic strains show a lipolytic activity which is twice the activity of non-toxinogenic strains. This enzymatic activity seems to be directly linked to the biosynthesis of toxins.