Isolation of a rat histidase cDNA sequence and expression in Escherichia coli--evidence of extrahepatic/epidermal distribution

Histidase (histidine ammonia-lyase) is a cytosolic enzyme responsible for catalyzing the non-oxidative deamination of histidine to urocanic acid. Full-length cDNAs encoding rat histidase have been isolated from a lambdaZAP liver cDNA library using a partial cDNA fragment obtained by PCR. Whereas the initial description of the rat histidase 3' untranslated sequence contained a rare polyadenylation signal sequence, the data presented encompass a more distant 28-bp region, possessing a nucleotide stretch (AATATAAA), identical to that in the mouse histidase cDNA. Dideoxynucleotide chain-termination sequencing of two clones obtained by in vivo excision yielded an additional 376 bp and 105 bp of 5' and 3' untranslated sequences, respectively. A selected rat histidase cDNA clone was introduced into the pET-16b prokaryotic vector and expressed in BL21(DE3)pLysS Escherichia coli. After purification by nickel-chelation chromatography, recombinant histidine-tagged protein was employed to raise anti-(rat histidase) immunoglobulin in a Japanese white rabbit. The polyclonal rabbit antibody recognized and formed immune complexes with rat and recombinant human histidase proteins. Immunoblots of crude rat organ extracts detected a spectrum of histidase expression extending beyond that observed in liver and skin. Among other histidase-positive cells were those of the renal cortex tubular epithelium, fundic mucosal glands of stomach, gastric intramuscular (Auerbach's) plexus, and adrenal cortex. Immunohistochemical studies of histidase in rat liver produced discrete staining of hepatocytes in association with portal triads (Rappaport zone I). Furthermore, in contrast with previous reports of activity confined to epidermal stratum corneum, our findings demonstrate immunoreactive protein within and limited to the adjacent stratum granulosum.

Embryonic germ cells induce epigenetic reprogramming of somatic nucleus in hybrid cells

Genomic reprogramming of primordial germ cells (PGCs), which includes genome-wide demethylation, prevents aberrant epigenetic modifications from being transmitted to subsequent generations. This process also ensures that homologous chromosomes first acquire an identical epigenetic status before an appropriate switch in the imprintable loci in the female and male germ lines. Embryonic germ (EG) cells have a similar epigenotype to PGCs from which they are derived. We used EG cells to investigate the mechanism of epigenetic modifications in the germ line by analysing the effects on a somatic nucleus in the EG-thymic lymphocyte hybrid cells. There were striking changes in methylation of the somatic nucleus, resulting in demethylation of several imprinted and non-imprinted genes. These epigenetic modifications were heritable and affected gene expression as judged by re-activation of the silent maternal allele of Peg1/Mest imprinted gene in the somatic nucleus. This remarkable change in the epigenotype of the somatic nucleus is consistent with the observed pluripotency of the EG-somatic hybrid cells as they differentiated into a variety of tissues in chimeric embryos. The epigenetic modifications observed in EG-somatic cell hybrids in vitro are comparable to the reprogramming events that occur during germ cell development.

Hepatic denervation ameliorates sodium and water retention in experimental cirrhosis in rats

Increased activity in the hepatic sympathetic nervous system may exacerbate salt and water retention in patients with liver cirrhosis. The aim of this study was to evaluate sodium and water homeostasis in rats with cirrhosis induced by diethylnitrosamine and to investigate the influence of hepatic denervation in this model. Animals were randomized into three groups: diethylnitrosamine-treated rats with (N = 13) and without (N = 8) hepatic denervation and control rats (N = 8). Rats were fed a normal salt diet (0.23% sodium ad libitum). The 24-hr measurements for sodium balance, water balance, and creatinine clearance were performed every two weeks for 12 weeks after surgery. Diethylnitrosamine-induced cirrhosis was confirmed histologically. The cumulative change in sodium balance in the innervated diethylnitrosamine-treated rat increased progressively and was significantly higher than the control during the last four weeks of the study. Meanwhile, rats with hepatic denervation showed significantly smaller changes in cumulative sodium balance at week 12 than those in the innervated group. The cumulative changes in water balance in the innervated group were significantly greater at weeks 10 and 12 than those of the denervated and control group, which remained unchanged throughout the study. Creatinine clearance in the innervated group decreased at weeks 10 and 12 by approximately 70% from baseline (P < 0.05); in contrast, it did not change significantly in the denervated group and control group throughout the study. These results demonstrated that hepatic denervation ameliorates sodium and water retention as well as glomerular function in cirrhosis model in rats.

Electrochemotherapy significantly inhibits the growth of colon 26 tumors in mice

Electrochemotherapy is a novel antitumor treatment involving the systemic administration of bleomycin followed by the delivery of electrical pulses to the tumor. The present study investigates the effects of electrochemotherapy on the growth of colon 26 cells inoculated subcutaneously into the backs of BALB/c mice. The mice were divided into the following four experimental groups: 20 that received no further treatment after the inoculation of colon 26 cells (control group); 20 that received 500 micrograms of bleomycin intraperitoneally 7 and 9 days after the inoculation (BLM group); 20 that received electric pulses to the tumor 7 and 9 days after the inoculation (EP group); and 30 that received electrochemotherapy 7 and 9 days after the inoculation (ECT group). During 28 days of observation, no deaths due to tumor progression occurred in the ECT group, but there were 18 in the control group, 11 in the BLM group, and 18 in the EP group. While weight loss was observed in all groups, it was most remarkable in the control group. Tumor growth was significantly inhibited in the ECT group, compared to the other experimental groups (P < 0.01). The results of this study demonstrated that electrochemotherapy significantly inhibited the growth of colon 26 tumors in mice, without causing any remarkable adverse effects.

Apoptosis, bcl-2 protein, and Fas antigen in thymic epithelial tumors

We examined 35 thymic epithelial tumors by immunohistochemical techniques to investigate the extent of apoptosis detected by in situ end-labeling of fragmented DNA and the expression of bcl-2 and Fas. There were 22 thymomas (4 medullary, 9 mixed, 3 predominantly cortical, 6 cortical), 3 well-differentiated thymic carcinomas (WDTCs), and 10 high-grade thymic carcinomas (HGTCs), according to the Müller-Hermelink histologic classification. The HGTC showed the highest apoptotic index of the tumor cells. The apoptotic indices of the thymomas and WDTCs were significantly lower than those of the HGTCs (P < .001), but there was no significant difference among each type of thymoma and the WDTCs. bcl-2 protein was expressed in the tumor cells of the medullary-type thymomas and of the HGTCs but not in the other types of thymoma or WDTC. Fas antigen was negative in the HGTCs but was predominantly expressed in thymomas and WDTCs with advanced clinical stages (P < .05). From the immunostaining pattern, WDTC might be more likely to belong to the class of thymoma than to the category of HGTC.

Nucleolar organizing regions in primary intracranial malignant lymphomas

Twenty-two non-immunocompromised patients with primary intracranial malignant lymphomas were examined on surgical material by using an argyrophilic method for the demonstration of nucleolar organizer regions as Ag-NORs. The histopathological classifications of 22 patients included 3 small lymphocytic, 7 small cleaved, 9 large cell. 1 mixed large and small, and 2 small non-cleaved type. The numbers of Ag-NOR of malignant lymphoma patients varied from 1.36 to 5.02 (mean 3.46 +/- 0.25). The mean Ag-NOR numbers in the histopathological subtypes were small lymphocytic 1.63, small cleaved 3.18, large 4.21, mixed large and small 3.47, and small non-cleaved 3.78. The number of Ag-NORs in small lymphocytic type was significantly less than small cleaved or large cell type (p < 0.05). The small cleaved type also had a smaller Ag-NOR number than the large cell type (p < 0.05). Except for two patients who had postoperative deterioration, 20 patients received postoperative irradiation ranging from 36 to 54 Gy (median, 46 Gy). Sixteen patients had complete response to radiotherapy, and 4 had good partial response. Ten patients had tumor recurrence within the remission period of 3 months to 7 years and 10 months (median 4.8 months). Three patients with intracranial relapse at a remote site had a significantly longer remission period (mean 57.3 months) than 7 with local relapse (mean 6.29 months), p < 0.05. The mean Ag-NOR number of the short and long remission period were 3.13 +/- 0.34 and 3.8 +/- 0.80, respectively. No significant difference was found between these two groups. The survival period was 3.2 months to 12 years (median 20 months). The Ag-NOR numbers of survival period less than or more than 20 months were 3.62 +/- 0.40 and 3.27 +/- 0.37, respectively. The Ag-NOR numbers did not correlate with either the remission or the survival period. These results indicate that Ag-NOR numbers may correlate with the histopathologic types, but not with the prognosis of primary intracranial malignant lymphomas.

Excitable membranes and synaptic transmission: postsynaptic mechanisms. Localization of alpha-internexin in the postsynaptic density of the rat brain

The synaptic localization of alpha-internexin, a brain-specific intermediate filament protein, was investigated immunohistochemically in the rat brain. The specificity of the antibody used in this study was confirmed by Western blotting and the antibody specifically reacted with alpha-internexin in the neurofilament preparation and in the postsynaptic density (PSD) fraction. The alpha-internexin immunoreactivity was distributed in neurons, especially in the somata and dendrites, throughout the cerebral cortex. Immunoelectron microscopic examination showed the immunoreactivity in the PSD, while neurofilament M was not in the PSD. Thus alpha-internexin and neurofilament M are differentially localized in neuronal cells. Alpha-internexin content in the PSD fraction was relatively high even before the period of synaptogenesis and the content in the fraction was unchanged between young and adult rats (2-6 weeks old). These results suggest a role of alpha-internexin for early development and organization of the PSD.

Mouse liver T cells: their change with aging and in comparison with peripheral T cells

Mouse liver contains both IL-2Rbeta- (or low positive) high T-cell receptor (TCR(hi)) cells and IL-2Rbeta+ intermediate TCR (TCR(int)) cells. TCR(int) cells consist of natural killer 1.1 (NK1)+ and NK1- subsets. NK1- TCR(int) cells increase constantly with age whereas TCR(hi) cells decrease. NK1+ TCR(int) cell proportions in the liver increase until middle age and decrease thereafter. Although NK1+ TCR(int) cells in other organs are few regardless of age, NK1- TCR(int) cells gradually appear in other lymphoid organs with aging. Skewed usage of Vbeta7 and Vbeta8 TCR was observed in NK1+ TCR(int) cells in the liver but the predominance was less obvious in NK1- TCR(int) and TCR(hi) cells in the liver and other organs. TCR V alpha14 messenger RNA (mRNA) was detected in NK1+ TCR(int) cells but not in the other two populations. In contrast, although NK1+ TCR(int) cells contain virtually no V alpha11+ T cells, NK1- TCR(int) cells contain a much higher proportion (approximately 12%) of V alpha11+ T cells, whereas approximately 4% of TCR(hi) cells are V alpha11+. NK activities of liver mononuclear cells (MNC) and splenocytes decrease with aging, although the former is always greater than the latter. NK activity of liver MNC is a function of NK cells, partly NK1+ TCR(int) cells but not NK1- TCR(int) cells or TCR(hi) cells. These results suggest that lymphocytes of liver and other organs at old age are no longer occupied solely by conventional thymus-derived T cells, and the increase of extrathymic IL-2Rbeta+ NK1- TCR(int) cells in liver and periphery could be closely related to immunological changes with aging.

Effectiveness of mammographic screening for breast cancer in women aged over 50 years in Japan

The optimal age for effective screening of subjects for breast cancer by mammography in Japan was studied based on the results of two mammographic screening systems (systems I and II) in Tokushima Prefecture. System I consisted of visit screening using a bus equipped with a mammographic apparatus. System II consisted of central screening performed at Tokushima Health Screening Center. The examinees numbered 2,500 and 3,707 in systems I and II, respectively. There was a significant difference between the two screening systems in the age distribution of the examinees. The detection rates of breast cancer were 0.6% and 0.24% in systems I and II, respectively, which are 2-5 times higher than that (0.12%) obtained by conventional screening using physical examination alone. The detection rate increased especially in the sixth and seventh decades of life. The sensitivity of mammography screening was 93.3% in system I and 81.1% in system II. Higher sensitivity (100%) than that (73%) of screening by physical examination was obtained in women aged over 50. The proportion of stage I was 60% in system I and 66.7% in system II, compared with 32-65% in the United States and Europe. The rates of no nodal involvement were high, being 77.8% and 83.3% in systems I and II, respectively, compared with 57-71% in other countries. Breast-conserving therapy was applied to 18 of the 24 patients with breast cancer detected by the two screening systems. In addition, in Wolfe's classification of mammograms, the proportion of DY (mammary dysplasia) pattern was remarkably low, being 3.2% in the sixth decade and 0.8% in the seventh decade, compared with 16.6% in women aged 49 years. These results indicate that mammographic screening is effective in women aged over 50 years in Japan, as has been found in other countries.

T-cell subset-specific expression of the IL-4 gene is regulated by a silencer element and STAT6

During development of CD4+ T lymphocytes in the periphery, differential expression of cytokine genes, such as those of interleukin (IL)-2 and IL-4, occurs in distinct T-cell subsets. IL-4 is a cytokine produced by T-helper 2 (Th2) cells, and the IL-4 receptor (IL-4R)-mediated signaling pathway is thought to be required for commitment to the Th2 phenotype. However, the molecular basis for development of the Th subset-specific production of IL-4 remains unclear. We demonstrate here that the IL-4 promoter is functional in Th1 and B cells which do not normally form IL-4 transcripts as well as in IL-4-producing T cells. Based on studies of the effect of several different upstream and downstream regions of the IL-4 gene on IL-4 promoter activity, a Th1-specific IL-4 silencer element was identified in the 3'-untranslated region. The silencer region contained a consensus sequence for a transcriptional factor that is normally regulated by the IL-4 R signaling pathway, STAT6. Nuclear expression of STAT6 protein, which was shown to bind to the silencer region, was observed in Th2 cells but not in Th1 cells. Deletion of the STAT6-binding site from the silencer region and inhibition of STAT6 function resulted in the appearance of silencing function even in Th2 cells. These results provide evidence that the silencer element, and the binding of STAT6 to this element, play a permissive role in determining the commitment into Th2 phenotype.

Autologous killing by a population of intermediate T-cell receptor cells and its NK1.1+ and NK1.1- subsets, using Fas ligand/Fas molecules

Self-reactive clones, estimated by anti-V beta monoclonal antibodies (mAb) in conjunction with the Mls system, are confined to a population of intermediate (int) T-cell receptor (TCR) (or CD3) cells (i.e. TCRint cells), but are not found among TCRhigh cells. The next questions to be answered are whether autologous killing is confined to TCRint cells and how such killing is mediated. In this study, 51Cr-labelled thymocytes of syngeneic or allogeneic origin were used as target cells (4-hr assay). When liver and splenic mononuclear cells (MNC) obtained from B6 mice were used as effector cells, prominent autologous killing was seen in liver MNC, but not splenic MNC. Such killing was not seen when thymocytes from B6-lpr/lpr mice (i.e. Fas-) were used as target cells, nor when liver MNC from MRL-gld/gld mice (i.e. Fas ligand-) were used as effector cells (target thymocytes of MRL(-)+/+ mice). Cell separation experiments using a cell sorter revealed that autologous killing was mediated for the most part by CD3int cells, while allogeneic killing was mediated entirely by natural killer (NK) cells, TCRint cells and TCRhigh cells. Among CD3int cells, the NK1.1+ subset (i.e. NK1.1+ T cells) manifested a higher level of autologous killing than did the NK1.1- subset. Consistent with the results of a functional assay, it was found by reverse-transcription-polymerase chain reaction (RT-PCR) assay that CD3int cells among liver MNC showed the expression of Fas ligand mRNA, while thymocytes expressed Fas mRNA. When class I major histocompatibility complex (MHC)- thymocytes (from beta 2-microglobulin-deficient mice) were used as target cells, NK cells, but not CD3int cells, showed potent cytotoxicity. These results suggest that autologous killing is a major function of TCRint cells with self-reactivity, and that such killing is mediated by means of Fas ligand/Fas molecules.

Self-reactive forbidden clones are confined to pathways of intermediate T-cell receptor cell differentiation even under immunosuppressive conditions

It is believed that self-reactive forbidden T-cell clones are generated by 'failure' of the pathway of T-cell differentiation in the thymus, if it is disturbed. We examined how such forbidden clones are generated under immunosuppressive conditions. Mice were treated with an injection of deoxyspergualin, FK506, or cycloporin A. From day 3, the number of cells yielded by various organs decreased. Because of the resistance of intermediate (int) T-cell receptor (TCR) cells (i.e. TCRint cells), they became more prominent in proportion than TCRhigh cells. TCRhigh cells are conventional T cells generated through the mainstream in the thymus, whereas TCRint cells are primordial T cells generated by the extrathymic pathway or an alternative intrathymic pathway. Similar to untreated mice, forbidden V beta 3+ and V beta 11+ clones in C3H/He (Mls-1b2a) mice were confined to TCRint cells after treatment; there was no leakage of forbidden clones into TCRhigh cells in the thymus and periphery. In parallel with the increase in the proportion of TCRint cells, the proportion of forbidden clones also increased under immunosuppressive states, especially in the liver. Liver mononuclear cells isolated from treated mice still had the potential to mediate autologous killing. The present results suggest that the generation of self-reactive clones is highly restricted to the pathways of TCRint cell differentiation even under immunosuppressive conditions.

Membrane attack complex of complement and 20 kDa homologous restriction factor (CD59) in myocardial infarction

In order to investigate the mechanism of deposition of the complement membrane attack complex (MAC) in cardiomyocytes in areas of human myocardial infarction, the 20 kDA homologous restriction factor of complement (HRF20; CD59) and complement components (Clq. C3d and MAC) were analysed immunohistochemically using specific antibodies. Myocardial tissues obtained at autopsy from nine patients who died of acute myocardial infarction were fixed in acetone and embedded in paraffin. The ages of the infarcts ranged from about 3.5 h to 12 days. In cases of myocardial infarction of 20 h or less, MAC deposition was shown in the infarcted cardiomyocytes without loss of HRF20. Where the duration was 4 days or more, the cardiomyocytes with MAC deposition in the infarcted areas also showed complete loss of HRF20. Outside the infarcts, HRF20 in the cardiomyocytes was well preserved without MAC deposition. The present study suggests that the initial MAC deposition in dead cardiomyocytes can occur as a result of degradation of plasma-membrane by a mechanism independent of complement-mediated injury to the membrane. Loss of HRF20 from dead cardiomyocytes may not be the initial cause of MAC deposition, but may accelerate the deposition process of MAC in later stages of infarction.

Enhancement of tumor radio-response by irinotecan in human lung tumor xenografts

We investigated the ability of 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11) to increase tumor radio-response in vivo using human lung tumor xenografts. The xenografts were treated with (1) CPT-11 (10 mg/kg) intraperitoneally on days 1, 5 and 9, (2) single dose radiation (10 Gy/leg) on day 1, or (3) a combination regimen of both treatments in which radiation was given 1 h after the first dose of CPT-11. DNA flow cytometry studies were performed to define the cell cycle changes following treatment for 1 to 12 h with 0, 0.5, 2.0 or 8.0 ng/ml SN-38, the major active metabolite of CPT-11. In both small cell lung cancer (MS-1) and small cell/large cell carcinoma (LX-1) xenografts, combination treatment resulted in significant tumor regression compared with the use of CPT-11 (P = 0.0005, 0.0053) or radiation treatment (P = 0.00221, 0.0035) alone. Neither severe body weight loss nor enhanced skin reaction was observed following the combined treatment. In flow cytometry studies, the proportion of cells in G2/M-phase, the most radio-sensitive phase, increased after 1 h exposure to the lowest dose of SN-38 (0.5 ng/ml). These findings suggest that CPT-11 is a potent radiosensitizing agent, and that its activity is related to the cell cycle. This is the first report to indicate that CPT-11 serves as a radiosensitizer in vivo.

Absolute dependence of T cell receptor(hi) cell generation and relative dependence of T cell receptor(int) cell generation on the thymus

Recent evidence indicates that conventional T cells are generated by the mainstream of T cell differentiation in the thymus and acquire a high density of T cell receptor expression (i.e. TCRhi). In contrast, primordial T cells (or NK1.1+ T cells) are generated by the extrathymic pathways or an alternative intrathymic pathway and express an intermediate density of TCR (i.e. TCRint). To obtain further evidence, it was examined how thymus grafting influenced the distribution of T cell populations in athymic nude mice. When BALB/c nu/nu mice were engrafted with thymocyte-depleted BALB/c+/+ fetal thymi, two changes emerged after grafting: nude mice generated TCRhi cells de novo in the periphery as well as in the grafted thymi, and the absolute number of interleukin-2 receptor beta chain+ TCRint cells increased prominently in number in the periphery. Among thymic hormones tested, the administration of thymosin alpha induced a slight expansion of CD3int cells in nude mice. To examine a possible interaction of TCRint cells with TCRhi cells in the periphery, B6 nu/nu mice (Ly5.2+) were injected with TCRhi cells purified from the spleen of B6 Ly5.1 congenic mice. In this case, TCRint (Ly5.2+) cells expanded well in all tested organs of nude mice. These results suggest that the generation of TCRhi cells is absolutely dependent on the thymus and that TCRint cells expand under the influence of the thymus (humoral) and due to interaction with thymus-derived conventional T cells.

Magnetic resonance galactography for a patient with nipple discharge

A new method of galactography using magnetic resonance imaging for a patient with nipple discharge is developed. The method is as follows; coronal T1-weight images are obtained after an injection of contrast medium of 1 mmol/L Gd-DTPA directly into the discharge duct, before and after rapid intravenous infusion of Gd-DTPA. A case of a 29-year-old woman with ductal carcinoma in situ with minimal invasion is reported, in which all portions of the entire discharge duct system is clearly shown as viewed from the surface and the surrounding area is enhanced with Gd-DTPA. The enhanced area is coincidental with the extent of the disease. This magnetic resonance galactography for patients with nipple discharge may be used to supplement conventional mammography and/or galactography especially for the evaluation of the extent of disease, although it is somewhat inferior to mammographic galactography in terms of differential diagnosis of ductal disease.

The immune system as a supersystem

I coined a term "supersystem" to designate highly integrated life systems such as the immune system, nervous system, and embryogenesis. While the mechanistic system is defined as a set of diverse elements so connected and related as to form an organic whole for a particular purpose, the "supersystem" engenders its own elements from a single progenitor. The diverse elements thus generated form relationship by mutual adaptation and coadaptation, and thus they create a dynamic self-regulating system through self-organization. It is a closed self-satisfied system, yet open to the environment, receiving outside signals to transduce them into internal messages for self-regulation and expansion. Unlike a mechanistic system, the "supersystem" has no defined purpose and determines its own fate by referring to its self-established behavioral pattern. Both the immune and nervous systems develop and function as a typical "supersystem." The prototype of the supersystem can be seen in embryogenesis and evolution. The concept of the supersystem can also be applied to the development of language, or a city, or other cultural phenomena that human beings have created as a result of their vital activities.

Ischemic colitis arising in watershed areas of the colonic blood supply: a report of two cases

There are several weak points in the colonic blood supply, known as watershed areas, which result from incomplete anastomoses of the marginal arteries. These watershed areas are more vulnerable to ischemic injury than other parts of the colon. We report herein the cases of two patients who developed ischemic colitis well localized in the cecum, and in the rectosigmoid region at Sudeck's point, respectively. This report and our review of the literature suggest that watershed areas, including the splenic flexure, or Griffith's point, Sudeck's point, and the ileocecal region, are high-risk regions for the development of ischemic colitis.

Two distinct commonly deleted regions on chromosome 13q suggest involvement of BRCA2 and retinoblastoma genes in sporadic breast carcinomas

BACKGROUND

Frequent allelic losses on the long arm of chromosome 13 in sporadic breast carcinomas suggest that a tumor suppressor gene(s) on 13q is involved in this type of carcinoma. The presence of a familial breast carcinoma susceptibility gene, BRCA2, and the retinoblastoma susceptibility gene (RB) on the same chromosomal arm implies that one or the other, or both, of these genes may be critically affected by those allelic losses.

METHODS

To investigate the possible involvement of BRCA2 and RB in sporadic breast carcinomas, the authors examined allelic losses in 246 breast carcinomas with 14 polymorphic microsatellite markers on 13q12.q14.

RESULTS

Allelic loss was observed in 95 of the 246 sporadic breast carcinomas (39%). Detailed deletion mapping identified two commonly deleted regions. The more proximal of these two segments was located in a 6-cM interval flanked by marker loci D13S289 and D13S267 and containing the BRCA2 gene; the more distal region was located in a 9-cM interval flanked by marker loci D13S328 and D13S172 and containing the RB gene. Allelic loss on 13q was found more frequently in tumors of the solid tubular histologic type (36 of 66; 55%) than in other types (52 of 146; 36%) (P = 0.0096). Furthermore, a significant association was observed between allelic loss on 13q and the absence of progesterone receptor (P = 0.0001).

CONCLUSIONS

The results indicate that BRCA2 and RB are independent targets of allelic loss and that inactivation of either of these genes may play a role in the development of some sporadic breast carcinomas, particularly those of the solid tubular type.

Level of myelopoiesis in the bone marrow is influenced by intestinal flora

Mice were orally given kanamycin (50 mg/day/ mouse) for 1 or 2 weeks. Almost all bacteria in the intestine were eliminated within a week. In parallel with this elimination, the level of granulocytes in the bone marrow decreased from 41 to 31%. Since the total number of bone marrow cells decreased as well (up to one-third), the decrease in the level of granulocyte generation in the bone marrow was substantial. Kanamycin is not absorbed from the intestine into the body; namely, it does not have a direct effect on the bone marrow. It is speculated that the interaction of granulocytes or epithelial cells with intestinal bacteria accelerates the production of free radicals and superoxids, some cytokines, or unknown factors and that such substances then stimulate the generation of granulocytes in the bone marrow. The present results suggest that intestinal flora and other resident bacteria are important for maintaining the level of myelopoiesis in the bone marrow.