Histological changes in rat duodenum mucosa after whole-body gamma irradiation.

In order to understand the mechanisms of intestinal injuries due to ionizing radiation, various groups of rats have been whole-body irradiated by gamma-rays at two dose rates (1 Gy/min and 1 Gy/hr), three doses (1, 2 and 4 Gy) and two post-irradiation times (24 and 48 hr). Duodenum samples of the animals were prepared for light microscopy, according to classical methods for histology and TUNEL reaction. A small number of morphological differences were observed within the mucosa between the two dose rates used. The extent and the number of lesions were more important at the slower dose rate (1 Gy/hr) and increased with the total dose. Clear cavities were seen inside the lamina propria which appeared like capillaries free of blood cells. The mitotic index calculated from crypt cells showed a regular decrease with the dose, which was exacerbated at 48 hr post-irradiation. On the other hand, the apoptotic index increased with the dose and the postirradiation time. Our results lead to hypothesize another mechanism of intestinal mucosa renewal allowing to explain mucosa denudations observed after radiotherapy. Thus we propose a new concept in which the duodenal mucosa renewal may occur by whole villi shedding into the duodenal lumen.

Genetic regulation of slowly progressing mild muscle atrophy in fast-twitch muscles of BUF/Mna rats.

BUF/Mna strain rats spontaneously develop slowly progressing mild-moderate muscle atrophy of extensor digitorum longus, tibialis, and extraocular muscles, which consist mainly of fast-twitch type fibers, at nearly 100% incidence. They have lighter extensor digitorum longus muscles than soleus muscles, when alive for more than 6 weeks. Genetic segregation of the development of the muscle atrophy was studied by crossing the BUF/ Mna strain with three other strains, ACI/NMs, WKY/NCrj, and BDIX, which were free of muscle atrophy. Two autosomal dominant susceptible genes, Mas-1 and Mas-2, determine the development of the muscle atrophy in these combinations of crosses.

Genetically determined thymus enlargement in the early life in BUF/Mna rats.

BUF/Mna (B) rat is a mutated strain, having much larger thymus than WKY/ NCrj (W), ACI/NMs (A), and F344 (F) rats throughout their life-span. Rats of the latter 3 strains have normal sized thymuses, being less than 5.3 in the thymus to body weight ratio (mg/g), when they were killed at 6 weeks of age. Genetic segregation of large thymus size in the B strain at 6 weeks of age was studied by crossing B rats with W, A or F rats. All of 3 types of the F1 hybrid rats between the B strain and the other strains showed intermediate thymus ratios between those of both parental strains. In F2 rats between the B and W strains, the distribution of thymus ratios showed about 5 different peaks. These findings might indicate that two polymeric autosomal loci, thymus enlargement-1 (Ten-1) and thymus enlargement-2 (Ten-2), can enlarge the thymus size in B rats. Histometrically, whole thymus and cortex areas of the B rats were 2-5 times larger than the W rats during 6-12 weeks of age, but medulla areas were slightly different between the strains, showing that larger thymuses in B rats were mainly due to the enlarged cortex areas.

Genetic mapping of genes regulating the thymus size in back-cross rats between the laboratory BUF/Mna strain and the MITE strain derived from the wild rat, Rattus norvegicus.

The thymoma prone BUF/Mna (B) rat is a useful model for studying the genes responsible for thymus enlargement during the stage of young growth. Among the strains of rats, B rats have the largest thymuses at all stages of life. A locus, Ten-1, which contributes to thymus enlargement in back-cross (BC) rats between the B and WKY/NCrj (W) strains, was mapped on chromosome 1. To determine the precise location of the locus, ¿B x(B x MITE)F1¿ BC rats were generated by crossing the B strain with the inbred MITE (M) strain, which was established from captured, Japanese wild rats, and were examined by linkage study using polymerase chain reaction with 67 microsatellite markers. Linkages with thymus enlargement were found in genotypes of seven markers, BSIS, LSN, MYL2, IGF2, PBPC2, D1Mgh11, and D1MIt6, by chi2-test and Student's t-test, which confirmed the presence of the genetic locus associated with thymus enlargement, Ten-1, in this region. Paradoxically, a suppressive locus, Tsu-1, to thymus enlargement was also found on chromosome 3, showing linkages of phenotype of the small thymus with genotypes of SCN2A, CAT, D3MIt16, and D3MIt13. By analyses of MAPMAKER/EXP and MAPMAKER/QTL, Ten-1 was mapped at 4.6 cM proximal from IGF2 locus on chromosome 1 and Tsu-1 at 4.0 cM proximal from CAT locus on chromosome 3, respectively.

Mapping of two genetic loci, Ten-1 and Ten-2, associated with thymus enlargement in BUF/Mna rats.

The thymoma-prone BUF/Mna rat is a useful model for human thymoma. Thymoma develops spontaneously in these rats at an incidence of nearly 100%. At pre-thymoma age, BUF/Mna rats have extremely large thymuses when compared with those of rats of the other strains, suggesting the presence of genes that regulate the thymus enlargement. We performed linkage study to identify the genetic loci associated with thymus enlargement in {(WKY/NCrj x BUF/Mna) F1 x BUF/Mna} backcross rats. Linkage study showed the significant associations between thymus size and markers on Chromosomes (Chrs) 1 and 13, suggesting the presence of two genes, Ten-1 and Ten-2, which regulate the thymus enlargement. Ten-1 was located between myosin light chain, muscle 2 (MYL2) and D1Mgh11 loci on Chr 1, and Ten-2 was located between synaptotagmin II (SYT2) and D13N2 loci on Chr 13.

Linkage of the athymic nude locus with the myeloperoxidase locus in the rat.

In rats of the BUF/Mna strain epithelial thymoma development is regulated by a single autosomal susceptible gene, Tsr-1. In pre-thymoma stage, BUF/Mna rats have extremely large thymuses, when compared with those of other strains of rats. The large thymus size of this strain is contributed by a thymus-enlargement gene, Ten-1. On the other hand, reduced thymus size and suppression of thymoma development were found in heterozygous BUF/Mna-rnu/+ rats. Linkage studies between RNU and microsatellite and restriction fragment length polymorphism markers in ([BUF/Mna-rnu/rnu x WKY/NCrj] F1 x WKY/NCrj)- and (WKY/NCrj x [BUF/Mna-rnu/rnu x WKY/NCrj] F1)- backcross rats have led to the localization of RNU on chromosome 10. The rat homolog of mouse Mpo (myeloperoxidase) was also assigned to the chromosome 10. The gene order on the chromosome was MYHSE (myosin heavy chain of embryonic skeletal muscle)--(1.0 centimorgan [cM])--SHBG (sex hormone-binding globulin)--(4.0 cM)--RNU (Rowett rat nude)--(10.0 cM)--MPO--(13.0 cM)--AEP (anion exchange protein). Conserved linkage of homologous loci mapped to rat chromosome 10 and mouse chromosome 11 supports the hypothesis that the RNU and MPO loci are rat homologs of the mouse nu and Mpo loci.

Chromosomal mapping of genetic locus associated with thymus-size enlargement in BUF/Mna rats.

The thymoma-prone rat of the BUF/Mna strain is a useful model for human thymoma. In this strain thymoma development is regulated by a single autosomal susceptible gene, Tsr-1. At pre-thymoma age, BUF/Mna rats have extremely large thymuses, when compared to those of other strains of rats. Genetic studies in crosses between BUF/Mna rats with large thymuses and WKY/NCrj rats with small thymuses suggested the presence of a major autosomal gene, Ten-1, which contributes to thymus enlargement in a backcross population. Linkage studies between Ten-1 and microsatellite markers in backcross rats of (WKY/NCrj x BUF/Mna)F1 x BUF/Mna have led to the localization of Ten-1 in chromosome 1. This result may provide an approach to clone Tsr-1, which could be allelic to Ten-1.

[Increased serum levels of soluble IL-2 receptor in food intolerance: possible mechanism of delayed immunity in milk intolerance]. / Aumento sérico del receptor soluble de IL-2 en la intolerancia alimentaria: posible mecanismo de inmunidad retardada en la alergia a la leche de vaca.

The levels of soluble interleukin-2 receptor (sIL-2R) were measured in 35 serum samples from children with food intolerance; 19 had an IgE-mediated sensitization and were considered as atopic patients, skin tests and RAST were negative in the remaining 16 children and they were diagnosed as having cow milk intolerance (CMI) Forty-three coeliac patients were included as a positive control group and 18 normal children as the negative control group. The atopic group showed normal values of sIL-2R (1,183 +/- 468 u/ml); however, it was increased in children with CMI (1,453 +/- 469 u/ml, p < 0.05). The sIL-2R mean value was highest in patients with gastrointestinal symptoms (1,458 +/- 461 u/ml, p: 0.03) and the presence of atopic dermatitis was not relevant. The sIL-2R was also elevated in 8 children with igE-mediated sensitization against cow's milk (1,477 +/- 328 u/ml, p < 0.05). These results suggest that a delayed cellular mechanism occurred in CMI, similar to that present in coeliac disease, although it was less severe. In addition, there is an overlap of humoral and cellular immunological mechanisms in the IgE-mediated sensitization to cow's milk, but we did not find this coincidence in the allergy to remaining foods. From a pathogenic point of view, to separate CMI from IgE-mediated allergies to milk does not seem to be sufficiently justified at the present time. It is possible that the atopy against cow milk proteins in children has a different immunological mechanism than the atopy to other foods, which would explain its better prognosis.

[Diagnostic evaluation of cervical adenopathies in childhood]. / Evaluación diagnóstica de las adenopatías cervicales en pediatría.

Between 1985 and 1990, 45 children were studied in an inpatient basis hospital because of cervical lymphadenopathy. This was the most important clinical sign in these patients. Forty-three had true adenitis. In the others, one was submaxillitis and one a sarcoma. The age range was from 2.1 to 13.3 years. Seven children (16%) had neoplastic adenitis (2 papillary carcinoma of the thyroid, 4 Hodgkin's lymphoma and one non-Hodgkin's lymphoma). Thirty-six patients had benign disorders (18 mononucleosis infections, 7 nonspecific adenitis, 5 infections of mycobacteria, 2 of toxoplasma and 2 of rickettsia, one cervical Whipple and one desmopathic adenitis). We did no find any differences related to age or morphological characteristics of the lymph nodes. The evolution time in patients with malignant tumors was 16.4 weeks and 9.6 weeks in the benign group. All of the cases with supraclavicular location had a lymphoma. The mean LDH in patients with malignant tumors was 214 U/L and 614 U/L in those with non-malignant tumors (p < 0.01).

Establishment of transplantable tumor lines and in vitro cell lines of malignant thymoma developed in a BUF/Mna rat.

A spontaneous malignant thymoma was found in an 18-month-old female BUF/Mna rat and serially transplanted subcutaneously in both syngeneic BUF/Mna rats (designated as MTH-R) and KSN nude mice (MTH-NM) for more than 5 years. Both tumors shared the histological appearance of sarcomatoid carcinoma as seen in the original tumor. However, MTH-NM grew faster than MTH-R in the respective hosts. The MTH-NM grew in both KSN-nude mice and BUF/Mna-rnu/rnu rats but not in BUF/Mna rats, the host of the original tumor. Three continuous tissue culture cell lines (MTHC-1, MTHC-2 and MTHC-3) were established from the MTH-NM tumors at the 2nd, 15th and 17th transplantation generations, respectively. The MTH-NM tumors and latter two tissue culture cell lines carried one or more mouse chromosomes, probably acquired by cell fusion with mouse cells during passages in vivo. The presence of the mouse chromosomes was confirmed by the presence of mouse DNA and of antibodies to the MTHC-2 and MTHC-3 cells in the sera of BUF/Mna rats transplanted with MTH-NM.

Adenomatous hyperplasia and adenomas in the lung induced by chronic feeding of butylated hydroxyanisole of Japanese house musk shrew (Suncus murinus).

A carcinogenicity study on butylated hydroxyanisole (BHA) was carried out in Japanese house musk shrews (Suncus murinus) (suncus), which have no forestomach. BHA was mixed with the basal diet and was processed into pellets. One hundred and twenty-two female and 130 male suncus were maintained with a diet containing 0, 0.5, 1.0 or 2.0% BHA for 80 weeks. All of the suncus of the 2.0% BHA groups died of bleeding in the gastrointestinal tract within 8 weeks after the commencement of the treatment. The majority of the animals in the other groups survived for greater than 52 weeks. Adenomatous hyperplasias of the lung were induced in suncus of both sexes of the 0.5 and 1.0% BHA groups at significantly higher rates than in the control groups. Lung adenomas were also induced in three suncus of the BHA groups. Pilosebaceous and musk gland tumors, mammary carcinoma, kidney hemangioma and other tumors developed in a few suncus, with no significant differences between the groups. The present study indicates that BHA induces adenomatous hyperplasia of the lung in the suncus.

Carcinogenicity and toxicity study of m-phenylenediamine administered in the drinking-water to (C57BL/6 x C3H/He)F1 mice.

m-Phenylenediamine (m-PDA, CAS: 108-45-2), a component of hair-dye formulations, was administered in the drinking-water to groups of female and male (C57BL/6 x C3H/He)F1 (B6C3F1) mice at concentrations of 0.02 or 0.04% for 78 wk. All the surviving mice were killed after a further 5-7 wk on untreated drinking-water, 83-85 wk after the start of treatment. Survival of the treated mice was similar to that of the corresponding controls. Body weights were significantly lower in high-dose females and males and somewhat lower in low-dose females than in the controls. The incidences of hepatocellular tumours were low to moderate in all male groups and in the control females, but the treated groups had significantly lower incidences than the controls. A few tumours of the lungs, haematopoietic organs and other organs and tissues were observed in all female and male groups. However, there were no statistically significant increases in the incidences of tumours in these organs and tissues in m-PDA-treated mice of either sex. Under the conditions of this study m-PDA showed no carcinogenic potential in either female or male B6C3F1 mice when administered in drinking-water. No non-neoplastic changes attributable to the compound were found in the treated mice, except for the deposition of brown pigment in follicular epithelial cells of the thyroid gland and in macrophages in some organs and tissues, and pigment impregnation of the bronchioli.

Characteristics of three human gastric cancer cell lines, NU-GC-2, NU-GC-3 and NU-GC-4.

Three human gastric cancer cell lines, NU-GC-2, NU-GC-3 and NU-GC-4 were established in vitro from the cancer tissues obtained from 3 patients during surgery. The pathological findings of the gastric tumors of these cases revealed poorly differentiated adenocarcinoma (and partial signet-ring cell carcinoma in the case of NU-GC-4). NU-GC-2 and NU-GC-4 were originally obtained from metastatic paragastric lymph nodes and NU-GC-3 was obtained from a metastatic tumor in the brachial muscle. The cells of NU-GC-2 and NU-GC-3 are polygonal in shape and grow as a monolayer sheet. NU-GC-4 cells, however, are mainly spherical in shape with a few free floating cells. Electron microscopy revealed epithelial characteristics in all 3 cell lines. The average doubling time of NU-GC-2 was 36.1 hours, that of NU-GC-3 was 38.2 hours and that of NU-GC-4 was 29.9 hours. The modal chromosome number of NU-GC-2 was 62, that of NU-GC-3 was 58 and those of NU-GC-4 grown in in vitro and in vivo were 52-54 and 53, respectively. In vitro and in vivo lines of NU-GC-4 were established from the same tumor. These two cell lines are quite similar in morphology, but slightly different in karyotype. The in vitro sensitivity to anticancer agents was highest in NU-GC-4 and lowest in NU-GC-2. Of the anticancer agents, mitomycin C and adriamycin were most effective on the cells of all 3 cell lines.

Cytological characteristics of cultured epithelial cells from thymomas in BUF/Mna rats.

Epithelial cells (ECs) from spontaneously developed thymomas in BUF/Mna rats were cultured, characterized and compared with ECs from normal thymuses. The ECs from thymomas had many more keratin filaments and PAS-positive vesicles in the cytoplasm than ECs from normal thymuses. The size and shape of ECs and their nuclei were heterogeneous and about 20% of ECs from thymomas had more than one nucleus. However, the growth rates and saturation densities of ECs from thymomas in monolayer culture were not markedly different from those of normal thymuses. The ECs from thymomas cultured in soft agar did not form any colonies. The distribution of the numbers of chromosomes found in ECs from thymomas was slightly broader than that in normal ECs, but no specific abnormalities nor marker chromosomes were noted. These findings indicate that ECs from thymomas are abnormal, but suggest that they are not malignant in nature.