Late appearance of a Philadelphia translocation with minor-BCR/ABL transcript in a t(7;11)(p15;p15) acute myeloid leukemia

We describe a patient with a t(7;11)(p15;p15) acute myeloid leukemia who was subsequently found to harbor the Philadelphia (Ph) translocation, in addition to the t(7;11), at the second relapse. A BCR/ABL transcript was detected at the second relapse by reverse transcription-polymerase chain reaction assay; the leukemic cells had a BCR/ABL fusion gene involving the minor breakpoint cluster region (minor-BCR; situated in intron 1 of the BCR gene). Although the Ph translocation is commonly detected in de novo acute leukemia and chronic myeloid leukemia as the primary leukemia-specific chromosomal translocation, our case suggests that this cytogenetic change might occur as an additional chromosomal change in neoplastic cells. Moreover, minor-BCR/ABL rearrangements may also occur as a late appearance of Ph translocation.

Nuclear bodies appearance rate in canine testicular Sertoli cell tumor

A number of nuclear bodies (NB) were observed in the canine testicular Sertoli cell tumors (SCT). We statistically examined nineteen cases of canine SCT concerning the NB appearance rate (NBAR), and also examined the NBAR in four cases of the normal testicular Sertoli cells. The mean value of the total number of the NBAR of SCT was significantly higher than that of normal Sertoli cells. The SCT were classified into three groups according to the Nielsen and Lein's histological classification (1974): intratubular SCT without invasion, intratubular SCT with invasion, and diffuse type SCT. The mean value of NBAR of the diffuse type SCT was significantly higher than that of the intratubular SCT with and without invasion, and there was no significant difference between the mean values of NBAR of the latter two groups. The distribution of NBAR of the diffuse type SCT was significantly different from that of the intratubular SCT with and without invasion. On the other hand, the individual differences of NBAR of the diffuse type SCT and the intratubular SCT with invasion was significantly higher than that of the intratubular SCT without invasion. The present study suggests that the increase of NBAR in canine SCT might be correlated with the tumor invasive progression.

Immortalisation of human oesophageal epithelial cells by a recombinant SV40 adenovirus vector

We introduced the origin-defective SV40 early gene into cultured human oesophageal epithelial cells by infection of a recombinant SV40 adenovirus vector. The virus-infected cells formed colonies 3-4 weeks after infection in medium containing fetal calf serum. When the cells derived from 'serum-resistant' colonies were then maintained in the serum-free medium with a low calcium ion concentration, some of them passed the cell crisis and kept growing for over 12 months. These cells, regarded as immortalised cells, resembled the primarily cultured oesophageal epithelial cells in morphology and had some of their original characteristics. Treatment of the cells with a high calcium concentration induced phenotypic changes. These cells still responded to transforming growth factor beta. When the immortalised cells were injected into severe combined immunodeficient mice, they transiently formed epithelial cysts, although the typical differentiation pattern of the oesophageal epithelium was not observed. These cysts regressed within 2 months without development into tumours. The results indicated that human oesophageal epithelial cells were reproducibly immortalised by infection with a recombinant SV40 adenovirus vector at relatively high efficiency. The immortalised cells should be useful in studies on oesophageal carcinogenesis and in assessing the cooperative effects with other oncogene products or carcinogens.

Identification of a 190-kDa protein as a novel substrate for the insulin receptor kinase functionally similar to insulin receptor substrate-1

Recently, we generated mice with a targeted disruption of the insulin receptor substrate-1 (IRS-1) gene and demonstrated that they exhibited growth retardation and mild insulin resistance, suggesting the presence of IRS-1-independent pathway that partially substitutes for IRS-1 in IRS-1-deficient mice (Tamemoto, H., Kadowaki, T., Tobe, K., Yagi, T., Sakura, H., Hayakawa, T., Terauchi, Y., Ueki, K., Kaburagi, Y., Satoh, S., Sekihara, H., Yoshioka, S., Horikoshi, H., Furuta, Y., Ikawa, Y., Kasuga, M., Yazaki, Y., and Aizawa, S. (1994) Nature 372, 182-186). We have examined the insulin-stimulated tyrosine-phosphorylated proteins in livers of wild type and IRS-1-deficient mice. Tyrosine phosphorylation of an 190-kDa protein (pp190) by insulin was significantly stimulated in livers of IRS-1-deficient mice, which was weakly observed in wild type mice in addition to IRS-1. We also demonstrated that pp190 was immunologically distinct from IRS-1 and was associated with both the 85-kDa subunit of phosphatidylinositol 3-kinase and the Grb2/Ash molecule as IRS-1. We identified pp190 as a novel substrate for insulin receptor kinase (IRS-2), which can bind both PI3-kinase and Ash/Grb2, and whose tyrosine phosphorylation is specifically induced in IRS-1-deficient mice. These data suggested that pp190 may play some physiological roles in insulin's signal transduction; furthermore, induction of tyrosine phosphorylation of pp190 may be one of the compensatory mechanisms that substitute for IRS-1 in IRS-1-deficient mice.

Antigenicities of enteropathogenic Escherichia coli, lysozyme, and alpha-1-antichymotrypsin on macrophages of genitourinary malacoplakia

Seven cases of genito-urinary malacoplakia were analyzed histologically, ultrastructurally and immunohistochemically in a comparison with two cases of xanthogranulomatous pyelonephritis. Immunohistochemically, von Hansemann cells and Michaelis-Guttmann bodies, both hallmarks for the diagnosis of malacoplakia, showed a common antigenicity for enteropathogenic Escherichia coli as cytoplasmic granules of varying sizes. These microscopic manifestations corresponded ultrastructurally to a series of phagolysosomal degradations of coliform bacilli. Serogroups against E. coli OK antigens, which were positive for malacoplakic cells, were not confined to a particular group. Macrophages of xanthogranulomatous pyelonephritis did not show the E. coli antigenicity. Antigenicity of lysozyme and alpha-1-antichymotrypsin on the von Hansemann cells was equivocal, but these enzymes were strongly positive on macrophages of xanthogranulomatous pyelonephritis. The macrophages of both malacoplakia and xanthogranulomatous pyelonephritis were positive for antihuman macrophage antibody. These results indicate that malacoplakia depends mainly on infection by a non-specific strain of enteropathogenic E. coli and may arise from defective digestive enzyme activity of infiltrating macrophages. Immunohistochemical analysis using antisera against E. coli OK antigens, lysozyme and alpha-1-antichymotrypsin was useful in identifying the prediagnostic stage of malacoplakia and in differentiating the lesion from xanthogranulomatous pyelonephritis.

Monoclonal-antibodies 5g8 and 2h6 are complementary immunohistochemical markers of lung carcinomas

Two murine monoclonal antibodies (MAbs) 5G8 and 2H6 were generated by fusing spleen cells obtained from mice immunized with human fetal tissue extract (14 weeks, Nonidet P-40 membrane fraction) from the early first trimester, followed by a booster injection of a lung cancer cell line. The MAb 5G8 recognized antigens with a molecular weight of 90, 50, 20 kDa, was neuraminidase-resistant and showed cross-reactivity with both carcinoembryonic antigen and non-specific cross-reacting antigen. The MAb 2H6 reacted with a sialomucin whose molecular weight was more than 1000 kDa and was different from previously known tumor associated-marker antigens. The distribution of the MAb-recognizing antigens in various tissues was investigated immunohistochemically. In malignant epithelial tumors of the lung, acinar adenocarcinoma and bronchioloalveolar carcinoma were positive for both MAbs; papillary adenocarcinoma, squamous cell carcinoma, and adenoid cystic carcinoma were positive only for MAb 5G8; solid carcinoma with mucin formation, small cell carcinoma, and large cell carcinoma were positive only for MAb 2H6. The combination of the two MAbs covered almost all histological types of lung carcinomas (23 of 24 cases) except carcinoid tumors. MAbs 5G8 and 2H6 reacted also with a restricted number of adenocarcinomas of the other organs. MAb 5G8 did not react with normal fetal or adult tissues, except for metaplastic gastric mucosa, acinar cells of the breast and leucocytes, whereas MAb 2H6 reacted with the surface epithelium of the stomach and colon, the Brunner gland of the duodenum and uterine cervix as well as the epithelium of the fetal digestive tract. Thus, MAb 2H6 which recognized oncofetal sialomucin, played a complementary role to MAb 5G8 as a CEA-related MAb in the immunohistochemical diagnosis of lung carcinomas.

Control of lymphopoiesis by p50csk, a regulatory protein tyrosine kinase

The csk gene encodes a nonreceptor protein tyrosine kinase that acts in part by regulating the activity of src-family protein tyrosine kinases. Since the src-family kinases p56lck and p59fyn play pivotal roles during lymphocyte development, it seemed plausible that p50csk might contribute to these regulatory circuits. Using a gene targeting approach, mouse embryonic stem cell lines lacking functional csk genes were generated. These csknull embryonic stem cells proved capable of contributing to many adult tissues, notably heart and brain. However, although csknull progenitors colonized the developing thymus, T and B cell differentiation were both blocked at very early stages. This represented a relatively selective interdiction of lymphocyte maturation, since csknull hematopoietic progenitors supported the development of normal-appearing MAC-1+ blood leukocytes, and the successful maturation of granulocyte/macrophage-colony-forming units from fetal liver progenitors. We conclude that p50csk regulates normal lymphocyte differentiation, but that it almost certainly does so by acting on targets other than p56lck and p59fyn.

Flagellar filament structure and cell motility of Salmonella typhimurium mutants lacking part of the outer domain of flagellin

We have isolated spontaneous mutants of Salmonella typhimurium which can swim in the presence of antifilament antibodies. The molecular masses of flagellins isolated from these mutants were smaller than that (52 kDa) of wild-type flagellin. Two mutants which produced the smallest flagellins (42 and 41 kDa) were selected, and the domain structures of the flagellins were analyzed by trypsin digestion and then subjected to amino acid sequencing. The two flagellins have deletions at Ala-204 to Lys-292 and Thr-183 to Lys-279, respectively. These deleted parts belong to the outer domain (D3) of flagellin, which is believed to be at the surface of the filament. These mutant filaments aggregated side by side in the presence of salt, resulting in disordered motility.

p53 controls proliferation of early B lineage cells by a p21 (WAF1/Cip1)-independent pathway

We examined a role of p53 in early B cell development using fetal liver (FL) cells from p53 deficient (-/-) mice. Expression of p53 was detected in early B lineage (pre-B) cells developed in the stromal cell-dependent FL cell culture. Proliferation of the pre-B cells from the p53(-/-) mice was augmented, suggesting that p53 negatively regulates proliferation of pre-B cells. Although p21 (WAF1/Cip1) is a downstream effector of p53 and mediates growth arrest by inhibiting the action of cyclin-dependent kinases, expression of p21 was also induced in the pre-B cells from p53(-/-) mice. These results indicate that expression of the p21 in pre-B cells is independent of p53 and that the regulatory effect of p53 on proliferation of pre-B cells is mediated by a p21-independent pathway.

Reduced hippocampal LTP and spatial learning in mice lacking NMDA receptor epsilon 1 subunit

The NMDA (N-methyl-D-aspartate) receptor channel is important for synaptic plasticity, which is thought to underlie learning, memory and development. The NMDA receptor channel is formed by at least two members of the glutamate receptor (GluR) channel subunit families, the GluR epsilon (NR2) and GluR zeta (NR1) subunit families. The four epsilon subunits are distinct in distribution, properties and regulation. On the basis of the Mg2+ sensitivity and expression patterns, we have proposed that the epsilon 1 (NR2A) and epsilon 2 (NR2B) subunits play a role in synaptic plasticity. Here we show that targeted disruption of the mouse epsilon 1 subunit gene resulted in significant reduction of the NMDA receptor channel current and long-term potentiation at the hippocampal CA1 synapses. The mutant mice also showed a moderate deficiency in spatial learning. These results support the notion that the NMDA receptor channel-dependent synaptic plasticity is the cellular basis of certain forms of learning.

[A case report of Epstein syndrome]

Epstein's triad which is a syndrome with the combination of macrothrombocytopenia, deafness and nephritis, is similar to Alport's syndrome. We report on a case of Epstein syndrome and describe the results of morphological examination of a renal biopsy, specimen. The patient was a 14-year-old girl with the diagnosis of chronic idiopathic thrombocytopenic purpura that had preseated from the age of 3 years. She was referred to Daisan Hospital of the Jikei University School of Medicine on April 1, 1991 for refractory thrombocytopenia. She had shown sensorineural hearing loss since the age of 6 years and her peripheral blood smear revealed giant platelets on admission. She was treated with interferon, prednisolone, and high-dose gamma-globulin (400 mg/day x 5 days). However, the platelet count did not increase, but hypermenorrhea continued. She subsequently showed proteinuria and hematuria. She underwent splenectomy and renal biopsy on August 12, 1992. The glomeruli appeared to be almost normal under light microscopy. The interstitium showed regional fibrosis containing foam cells and the renal tubuli showed mild atrophy. Under electronmicroscopy, the basement membrane of the glomeruli was associated with mesangial interposition and the lamina densa was split into several layers. These ultrastructural findings were compatible with those of Alport's syndrome.

A clinical and immunohistochemical study of papillary adenocarcinoma of the prostate

Clinical and immunohistochemical studies were conducted to evaluate prostatic papillary adenocarcinoma and prostatic papillary hyperplasia. Subjects consisted of 5 cases of papillary adenocarcinoma and 2 cases of papillary hyperplasia. There is no conclusive clinical factor for preoperative diagnosis, but we attach importance to endoscopic findings. PSA, PAP, high molecular weight cytokeratin, and PCNA were evaluated immunohistochemically. PSA became positive in every instance but one--a case of papillary adenocarcinoma which became +/-. PAP was + in all cases, except for 1 case of papillary adenocarcinoma. Basal cells were positive for high molecular weight cytokeratin in 2 cases of papillary hyperplasia but were missing in papillary adenocarcinoma. Although PCNA was free from positive nuclei in papillary hyperplasia, positive nuclei were found in all cases of papillary adenocarcinoma. Considering these immunohistochemical results, papillary adenocarcinoma can be said to originate in the glandular epithelium of the prostate, as does ordinary prostatic carcinoma.

Case report of a malignant Brenner tumor with hyperestrogenism

A rare malignant Brenner tumor of the ovary presenting with hyperestrogenism in a 79 year old woman was examined immunohistochemically and by light and electron microscopy. High pre-operative serum and urinary estrogen concentrations, low serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels, and histologically confirmed atypical endometrial hyperplasia suggested the presence of hyperestrogenism. The reduction in serum and urinary estrogen and the increase in serum LH and FSH concentrations after tumor removal confirmed that the tumor was synthesizing estrogen. Histologically, the malignant element was predominantly a squamous cell carcinoma. Transitional cell carcinoma was partially found on the cyst wall. There was a spectrum of morphologic changes between benign and malignant elements with an intermediate area with a proliferating Brenner tumor. Immunohistochemically, only the carcinoembryonic antigen was positive exclusively on the malignant element as well as in the microcyst in the benign epithelial cord, whereas all of the markers for germ cell tumors were negative. The ultrastructural features of the stromal cells were of two types: fibroblasts and steroid-producing cells. The latter type of cells might correspond morphologically to estrogen-producing cells. The present case is the fourth report showing a malignant Brenner tumor combined with apparent hyperestrogenism.

[Analysis of T cell subsets in autoimmune hemolytic anemia patients]

To clarify a role of immunoregulatory T cells in the pathophysiology of autoimmune hemolytic anemia (AIHA), we investigated T cell subsets in the peripheral blood of 15 patients with AIHA by two color analysis using flow cytometry. Consequently both CD4+ cells and CD4+CD45RA+ cells decreased in proportion, irrespective of the disease activity (active or remission phase). CD4+CD45RA+ cells are regarded as naive T cells. Incidentally the ratio of CD45RA+ cells in CD4+ cells also fell in the low level in active phase, but it recovered to the normal ratio in remission. On the other hand, CD8+ cells and CD8+ +S6F1+ cells that may represent activated cytotoxic T lymphocytes increased in active phase and then both entered the normal range in remission. These findings suggest that AIHA could be caused partly by the alternative balance of CD4+CD45RA+ cells probably constituting a member of IRT and moreover by the activation of CTL.

Stimulation of transcription in cultured cells by high mobility group protein 1: essential role of the acidic carboxyl-terminal region

Several in vitro studies have suggested that high mobility group (HMG) protein 1 has a role in gene regulation as a trans activator or quasi-transcription factor. However, data on the molecular functions of HMG1 protein in these reactions are contradictory or obscure. In order to assess whether HMG1 protein does, in fact, have transcriptional activation potential, two assay systems in cultured cells were employed. HMG1 protein introduced into COS-1 cells as a complex with a reporter plasmid carrying the lacZ gene enhanced the level of the gene expression. Cotransfection of an expression plasmid carrying HMG1 cDNA into the cells with the reporter plasmid enhanced the activity of beta-galactosidase 2-3-fold in comparison with that of the control effector plasmid. The enhancement was proved to be dependent not on the replication but on the transcription of the reporter plasmid. In the cotransfection experiments, an expression plasmid the HMG1 molecule lacking the acidic carboxyl terminus repressed the expression of the reporter gene. The binding of an HMG1 protein variant lacking the acidic carboxyl terminus to DNA gave an extremely large shift of gel retardation in comparison with the complete HMG1 molecule. Together, these results indicate that HMG1 protein can enhance expression in cells in culture at the step of gene transcription and that the DNA binding domains comprising two-thirds of the HMG1 protein molecule are responsible for the inhibition property. Also, the acidic terminus of the HMG1 molecule is essential for the enhancement of gene expression in addition to elimination of the repression caused by the DNA binding. (ABSTRACT TRUNCATED AT 250 WORDS)

Bone marrow transplantation from Fv-4-resistant donors rescues Friend leukemia virus-infected mice from leukemia: a model of bone marrow transplantation therapy against retroviral infection

Bone marrow transplantation experiments were conducted in mice in order to develop an experimental bone marrow transplantation therapy model, with which to investigate possible means to cure retrovirus-infected hosts with bone marrow or stem cells from virus-resistant donors. In one experiment, lethally irradiated Friend leukemia virus (FLV)-sensitive C3H/He (C3H; Fv-2s, Fv-4s, Rfv-1s, Rfv-2s Rfv-3s) mice were transplanted with (i) bone marrow cells from FLV-resistant BALB/c-Fv-4Wr (C4W; Fv-2s, Fv-4r, Rfv-1s, Rfv-2s, Rfv-3s) mice (C4W --> C3H) or (ii) a mixture of bone marrow cells from C4W and C3H mice (C4W + C3H --> C3H). They were then inoculated with FLV 3-4 months later and leukemia development was examined. The results indicated that C4W --> C3H chimeras were completely resistant to FLV-induced leukemogenesis and that C4W + C3H --> C3H mixed chimeras that contained as low as 30% C4W-derived cells, or as high as 70% C3H-derived cells, did not develop leukemias. In another experiment, bone marrow cells from C57BL/6 (B6; Fv-2r, Fv-4s, Rfv-1r, Rfv-2r, Rfv-3r) or C4W donors were grated to FLV-sensitive DBA/2 mice (DBA; Fv-2s, Fv-4s, Rfv-1s, Rfv-2s, Rfv-3s) that had been infected with FLV 6 days earlier (DBA-FLV). The results indicated that most, if not all, FLV-infected DBA mice which received bone marrow transplantation from B6 donors developed B6-derived leukemias, although the survival time of these mice was dramatically prolonged as compared to that of untreated DBA-FLV mice. In contrast, bone marrow transplantation from Fv-4r-bearing C4W donors successfully rescued FLV-infected DBA mice from leukemic deaths. Thus, the bone marrow transplantation therapy against retroviral infection of hemopoietic cells was shown to be feasible, provided that donor cells carry a resistant allele that functions via receptor blockade as in the case of Fv-4r, but less effective when the roles of the resistant alleles partially interfered with the virus replication, leukemic transformation and/or cycling of target cells as suggested for Fv-2r gene action, or to resist virus infection by immunological means as are known for Rfv-1r, Rfv-2r and Rfv-3r genes which are also carried by B6-strain mice. Implication of these findings on the somatic gene therapy against retrovirus infection diseases in man are discussed.

Identification of major tyrosine-phosphorylated proteins in Csk-deficient cells

Csk is a non-receptor protein-tyrosine kinase that acts as a negative regulator of Src family tyrosine kinases. Csk-deficient mouse embryos exhibited developmental defects including inability to turn and impaired formation of neural tube. In these embryos, an accumulation of tyrosine phosphorylated proteins was observed as a consequence of constitutive activation of Src family kinases. In order to identify those tyrosine phosphorylated proteins, we established a Csk-deficient cell line from embryos lacking both Csk and the anti-oncogene product p53. On surveying several proteins known as Src substrates, we found that phosphorylation level of p80/85 (cortactin) was markedly elevated in the Csk-deficient cells. Enhancement of cortactin phosphorylation was also seen in Csk-deficient embryos. Furthermore, immunoprecipitated Src was able to directly phosphorylate cortactin in vitro. Thus, we suggest that cortactin is a good substrate of activated Src family kinases in vivo and may play important roles in signaling pathways mediated by Src family kinases.

A novel nonreceptor tyrosine kinase, Srm: cloning and targeted disruption

We have isolated a novel nonreceptor tyrosine kinase, Srm, that maps to the distal end of chromosome 2. It has SH2, SH2', and SH3 domains and a tyrosine residue for autophosphorylation in the kinase domain but lacks an N-terminal glycine for myristylation and a C-terminal tyrosine which, when phosphorylated, suppresses kinase activity. These are structural features of the recently identified Tec family of nonreceptor tyrosine kinases. The Srm N-terminal unique domain, however, lacks the structural characteristics of the Tec family kinases, and the sequence similarity is highest to Src in the SH region. The expression of two transcripts is rather ubiquitous and changes according to tissue and developmental stage. Mutant mice were generated by gene targeting in embryonic stem cells but displayed no apparent phenotype as in mutant mice expressing Src family kinases. These results suggest that Srm constitutes a new family of nonreceptor tyrosine kinases that may be redundant in function.

Percentages of bone marrow blasts and chromosomal changes in patients with refractory anemia help to determine prognoses

We statistically analyzed the hematologic findings of patients with refractory anemia (RA) to identify parameters associated with a poor prognosis. We first separated the RA patients into two groups: one group with disease progression and one without. The patients with disease progression were predominantly male and had a significantly higher percentage of bone marrow (BM) blasts at the time of diagnosis (3.06 +/- 1.29% vs. 1.44 +/- 1.38%, P < 0.005). This finding was confirmed when the patients were separated into the two groups; those who survived and those who expired (BM blasts: 2.68 +/- 1.59% vs. 1.37 +/- 1.27%, P < 0.005). The survival probabilities were calculated depending on whether or not the RA patients had > or = 3% BM blasts. The RA patients with > or = 3% BM blasts had a significantly worse prognosis (P < 0.01) than the patients with < 3% BM blasts. Notably, the RA patients with > or = 3% BM blasts did not show any significant differences in the incidence of disease progression, mortality rate, or survival probability, when compared with the patients with RA with an excess of blasts (RAEB). The present findings indicate that RA patients are heterogeneous with regard to prognosis, and the RA patients with > or = 3% BM blasts might have a poorer prognosis than those with fewer BM blasts. Thus we propose a general approach in predicting the prognosis of RA patients: those with complex chromosomal changes will expire shortly. Secondly, when the patients do not have any complex changes, the prognosis might be linked to the percentage of BM-blasts at the MDS diagnosis.

Roles of FliK and FlhB in determination of flagellar hook length in Salmonella typhimurium

The length of flagellar hooks isolated from wild-type and mutant cells with various hook lengths were measured on electron micrographs. The length of the wild-type hook showed a narrow distribution with a peak (+/- standard deviation) at 55.0 +/- 5.9 nm, whereas fliK mutants (so-called polyhook mutants) showed a broad distribution of hook lengths ranging from 40 to 900 nm, strongly indicating that FliK is involved in hook length determination. Among pseudorevertants isolated from such polyhook mutants, fliK intragenic suppressors gave rise to polyhook filaments. However, intergenic suppressors mapping to flhB also gave rise to hooks of abnormal length, albeit they were much shorter than polyhooks. Furthermore, double mutations of flhB and flgK (the structural gene for hook-associated protein 1; HAP1) resulted in polyhooks, suggesting another way in which hook length can be affected. The roles of FliK, FlhB, and HAP1 in hook length determination are discussed.

Fyn expression during early neurogenesis in mouse embryos

Fyn is a member of the Src family of tyrosine kinases which are thought to play important roles in cell to cell interactions during morphogenesis. The developmental profile of Fyn expression was examined using mutant mice in which lacZ gene was introduced into this locus. The expression was characteristic in the neural system. Though at low levels, it was detected in the headfold at embryonic day (E) 7.5 and in the luminal surface of neuroectoderm along the entire neural groove at E8.5. The expression appeared regional in rhombomeres at E8.5 and E9.5. Consistent expression was also found at a low level in the notochord. The expression was high in later stages of the neural tube which consists of three layers; it was in the marginal layer but not in the germinal layer. High expression was also found in developing dorsal root filaments of neural crest origin. Non-expression in dividing neuroepithelial cells and expression in developing neural fibers appeared ubiquitous features of Fyn expression throughout the entire brain.

Cytotoxic effect of extracellular ATP on L1210 leukemic cells and normal hemopoietic stem cells

The cytotoxic effect of extracellular adenosine triphosphate (ATP) was examined on normal murine hemopoietic stem cells and a representative leukemic cell line (L1210). After L1210 cells were incubated with 4 mM ATP for 3 h, 3H-thymidine incorporation was almost completely inhibited. The number of viable L1210 cells was also significantly decreased and L1210 colony formation was suppressed to approximately 30% of the control level after treatment. The CFU-GM survival rate was reduced to 70%, however, CFU-S and marrow nucleated cell numbers were not changed after the same treatment with ATP. All mice that were injected with the untreated mixture of normal marrow cells (3.3 x 10(4)) and L1210 cells (3.3 x 10(3)) died of leukemia within 18 days. On the contrary, 85% of the recipients given ATP-treated grafts survived more than 70 days. These findings indicate that ATP extra vivo treatment is useful for purging the residual leukemic cells in autologous bone marrow transplantation.

Increased UV-induced SCEs but normal repair of DNA damage in p53-deficient mouse cells

UV-induced sister chromatid exchanges (SCEs) in p53-deficient mouse cells were studied to obtain more evidence regarding the involvement of p53 protein in the DNA repair pathway as a checkpoint protein. After 5 J/m2 UV irradiation, mutant-type homozygous cells for p53-deficiency showed the same number of SCEs as the heterozygous and wild-type homozygous cells. In the heterozygous and wild-type homozygous cells, no further increase of SCEs was observed after 10 J/m2 UV irradiation. In contrast, in mutant-type homozygous cells about twice as many SCEs were induced by 10 J/m2 UV as by 5 J/m2 UV. In mutant-type homozygous cells, fractions of S-phase cells decreased just after 10 J/m2 UV irradiation, but recovered to higher than control levels within a short time, while in heterozygous and wild-type homozygous cells, the decrease in S-phase cells was prolonged by more than 6 hr and no increase above control levels was observed. Although no difference in UV sensitivity and repair of UV-induced DNA damage was found among the 3 genotypes, which were determined by the relative colony-forming ability after UV irradiation and removal of thymine dimers and (6-4) photoproducts from cellular DNA, our data strongly suggest an impaired checkpoint function in p53-deficient cells when DNA is damaged.

Selective planting of cationized, haptenized ovalbumin on the rat tubular basement membrane

We developed an experimental protocol for planting exogenous antigens with different molecular weights and charges on the constituents of the renal tubulointerstitium. The cationized antigens were injected selectively into the left renal arteries of Wistar rats. Antigen localization was documented by immunohistochemistry on frozen sections. Cationized bovine serum albumin (BSA; 68 kDa, isoelectric point = 9.5) localized almost exclusively along the glomerular capillary wall. After application of highly cationic polyethyleneimine, cationized BSA given subsequently was found in a linear distribution along the glomerular capillary wall and along the peritubular capillaries. The fate of highly cationized ovalbumin conjugated with trinitrophenol (TNP-OA), subjected to gel filtration to obtain monomers (42 kDa, isoelectric point > 10) differed; it was deposited in a linear pattern on the tubular basement membrane (TBM) and Bowman's capsule, and remained up to 36 h after injection. Noncationized, monomeric TNP-OA (42 kDa, isolectnic point = 4.6) showed fine granular deposition in the tubular epithelium exclusively. These findings indicate that the barrier of the glomerular BM acts selectively on antigens with different molecular weights. They either settle on the peritubular capillaries, after passing the glomerular, or reach the urinary space, after which they are reabsorbed by the tubular epithelial cells to reach the TBM.