Metabolism and acid-base status during hypoxic ventilatory depression

The ventilatory response to acute systemic hypoxia has been thought to be determined by the balance between hypoxic stimulation via peripheral chemoreceptors and hypoxic inhibition of the respiratory neurons. In moderate-severe hypoxia, the latter predominates the former resulting in ventilatory "depression" (HVD). However, ventilation relative to metabolic rate (V.O2) during HVD is "not depressed" but remains increased because of associated reduction in O2 uptake (V.O2). The experiment presented here was conducted to elucidate the changes in CO2 output (V.CO2) and acid-base status during hypoxia and their role in ventilatory regulation. Ventilation, metabolic rate (V.O2, V.CO2), acid-base status and blood lactate concentration were measured during and after inhalation of hypoxic gases in halothane-anesthetized and spontaneously breathing rats. The HVD occurred at FIO2 0.08 with increased blood lactate concentration, increased venous PCO2 and a large drop in venous pH without significant changes in arterial pH and PCO2. Furthermore, the amount of reduction in V.CO2 during HVD was much smaller than that of V.O2 and the V.CO2/V.O2 ratio increased. These findings suggest that CO2 output becomes relatively higher than O2 consumption in moderate-severe hypoxia. The possible origin of CO2 accumulation in the venous blood, such as the buffering of lactic acid by bicarbonate, and its role in ventilatory stimulation are discussed. Since there was no large increase in V.E and metabolic rate in the post-hypoxic period, "O2 debt" during HVD was small.

Experimental disseminated trichosporonosis in mice: tissue distribution and therapy with antifungal agents

Mice treated with cyclophosphamide were infected intravenously with titrated doses of Trichosporon asahii TIMM3140 or TIMM3144. Mortality and survival time correlated with inoculum size and fungal growth was found in the lung, heart, liver, spleen, kidney and brain. Fluconazole and amphotericin B prolonged survival time and reduced the CFU in the kidney, with fluconazole being superior to amphotericin B. The serum level of (1-->3)-beta-D-glucan was reduced by antifungal therapy and correlated well with the CFU/organ in kidney, but not CFU/ml in blood.

[Evaluation of marble burying behavior: induced alteration of monoamine metabolism in mouse brain]

Evaluation of marble burying behavior (MBB) housing-induced alteration of monoamine metabolism in mouse brain was performed by measuring metabolite levels with HPLC-ECD. Isolated housing of mice, each in a cage (22 x 32 x 14 cm; sawdust, 1-mm diameter; 5 cm in thickness) with 15 evenly spaced glass marbles on the floor (2.5-cm diameter; control, without marbles) for 24-168 hr, 5-HIAA contents were decreased in three regions: the midbrain, thalamus and hypothalamus. 5-HT turnover was not inhibited except for in the hypothalamus due to the decreases of 5-HT in the other two regions. On the other hand, DOPAC content and DA turnover were decreased in four regions: striatum, midbrain, thalamus, hypothalamus. The decrease in hypothalamic monoamine neurons was observed notably after 72 hr of MBB housing. No alterations were observed in feeding, water-drinking, spontaneous locomotor activity, number of buried marbles, serum corticosterone and serum glucose concentrations during MBB keeping compared with the control mice. These results suggested that the isolated mouse housed in a cage with evenly spaced glass marbles for a long period may be a model animal for alteration of monoamine metabolism in brain regions without physical infringement.

[Study on risk factors and late results of coronary artery bypass grafting for acute myocardial infarction]

Study was made on the operative results, risk factors, and late results of coronary artery bypass grafting (CABG) for acute myocardial infarction (AMI) conducted at our hospital. The subjects of the present study were 70 cases of AMI who underwent CABG during a period of five years from January 1991 to December 1995. They were composed of 61 males and 9 females whose mean age was 61.9 years. LMT disease was observed in 13 cases and preoperative shock in 18 cases. The mean aortic cross-clamp time was 64 minutes with the mean extracorporeal circulation time being 134 minutes and the mean number of grafts being 2.5. The mean preoperative-postoperative peak creatine kinase was 4479 IU/L. The number of operative deaths was 14 with a mortality rate of 20%. When compared with elective cases of CABG conducted during the same period with a mortality rate of 2.7%, the operative result of AMI was poor. The mortality rate by risk factor was 40% for age of 70 years or more, 46.2% for complication of LMT disease, 52.9% for preoperative shock, 58.3% for preoperative C.I. of less than 2.0, 80% for postoperative C.I. of less than 2.0, 28.2% for conduct of postoperative circulatory support, and 42.1% for peak creatine kinase of 5000 IU/L or more. Aortic cross-clamp time and reperfusion time (interval from onset of AMI to aortic declamp) were found not to be risk factors. Late death accounted for 5 cases including one case of cardiac death due to suspected AMI. Survival rate excluding operative deaths and hospital deaths was 98% in one year and 83.9% in five years. When compared to non cardiacevent cases, the survival rate of positive cardiac event cases was significantly poor. The operative results of severe myocardial ischemia cases represented by cases of complication of LMT disease were poor and it is considered that improvement of intraoperative myocardial protection and aggressive use of postoperative circulatory support are necessary in the future. The survival cases of those who could endure surgery was comparatively satisfactory, but when cardiac event developed, prognosis was poor and thus more rigid follow-up is considered to be necessary.

[Results of cardiac operation and thoracic aortic operation in patients aged 75 years or older]

A total of 121 patients aged 75 years or older underwent cardiac operation or thoracic aortic operation at our hospital between 1988 and February 1997. They were composed of 74 cases of ischemic heart disease, 22 cases of valvular disease, 1 case of myxoma, and 24 cases of thoracic aortic disease. Operative mortality rate was 13.5% in ischemic heart disease, 4.2% in valvular disease and myxoma, and 25% in thoracic aortic disease. In ischemic heart disease, the operative mortality rate was especially high in emergency operation for acute myocardial infarction. In thoracic aortic operation, further improvement should be made with regard to preoperative and intraoperative management.

Osteoclast precursors in bone marrow and peritoneal cavity

Osteoclasts differentiate from cells that share some phenotypes with mature macrophages and monocytes, but early precursors for osteoclasts still remain obscure. To characterize osteoclast precursors, using monoclonal anti-c-Fms and anti-c-Kit antibodies, bone marrow cells were separated and the frequency of clonogenic progenitors were measured. Osteoclast precursors in the bone marrow mainly expressed c-Kit and diminished in frequency when they expressed c-Fms. In contrast to bone marrow, the precursors in the peritoneal cavity were enriched with a population of c-Fms+. Injection of these antibodies into mice demonstrated that peritoneal osteoclast precursors were sensitive to anti-c-Fms but not to anti-c-Kit antibodies, whereas those in bone marrow only declined in the presence of both antibodies. Meanwhile, c-Fms as opposed to c-Kit played an essential role in the generation of osteoclasts in cultures. We also compared osteoclast precursors with colony forming cells (CFU-M) by a macrophage colony stimulating factor. CFU-M in bone marrow decreased when anti-c-Kit antibody was administered and no CFU-M was detected in peritoneum. In this study, we show differences between proliferative potential osteoclast precursors maintained in bone marrow and peritoneum and between CFU-M and osteoclast precursors.

Phorbol ester enhancement of IL-3-dependent proliferation of primitive hematopoietic progenitors of mice in culture

Protein kinase C (PKC) is a Ca++- and phospholipid-dependent protein kinase activated by diacylglycerol that is either released from cell membranes in response to certain growth factors or mimicked by 12-O-tetradecanoyl phorbol-13-acetate (TPA). We studied the effects of TPA on interleukin-3 (IL-3)-dependent colony formation of mouse bone marrow cells from mice injected with 5-fluorouracil 2 days before examination in order to clarify the significance of PKC in the proliferation of primitive hematopoietic progenitors. Although TPA alone did not support colony formation, TPA in combination with IL-3 increased colony numbers from 1.5 to 2 times that formed with IL-3 and vehicle. TPA increased not only the granulocyte/macrophage colonies, but also the multilineage colonies. A sequential colony count showed that TPA, unlike IL-6, did not hasten the appearance of colonies. Because TPA enhanced IL-3-dependent colony formation derived from lineage-negative marrow cells obtained from mice that received 5-FU 2 days before, it is possible that it might act directly on primitive progenitors. Prolonged pretreatment of marrow cells with TPA prevented TPA-augmented colony growth. Calphostin C, a specific PKC inhibitor, and certain specific tyrosine kinase inhibitors, such as genistein and herbimycin A, abrogated the enhancing effects of TPA on IL-3-dependent colony formation. These data suggest that TPA had a direct effect on the primitive progenitors and enhanced IL-3-dependent colony formation via activation of PKC and certain tyrosine kinases.

Expression of MAGE genes in osteosarcoma

Expression of MAGE genes that encode tumor-rejection antigens recognized by cytotoxic T lymphocytes with major histocompatibility complex class-I antigens was investigated in human osteosarcomas (20 cell lines and eight fresh tumor tissues). MAGE-1, 2, 3, 4, and 6 genes were expressed at the mRNA level in 11 (52.4%), 10 (47.6%), 10 (47.6%) one (4.8%), and 10 (47.6%) of 21 tumor cell lines, respectively, and in five (62.5%), six (75%), five (62.5%), one (12.5%), and five (62.5%) of eight fresh tumor tissues as determined by the reverse transcription-polymerase chain reaction method. MAGE-1 or 4 protein was detected by immunoblot analysis in eight of 11 or one of one tumor cell lines, respectively, where it was expressed at the mRNA level. Major histocompatibility complex class-I antigens were expressed in 19 of 21 tumor cell lines. These results suggest that MAGE tumor-rejection antigens are expressed in substantial numbers of osteosarcomas in a major histocompatibility class-I-restricted manner.

Ca2+ signaling and intracellular Ca2+ binding proteins

Changes in cytosolic Ca2+ concentrations evoke a wide range of cellular responses and intracellular Ca(2+)-binding proteins are the key molecules to transduce Ca2+ signaling via enzymatic reactions or modulation of protein/protein interations (Fig.1). The EF hand proteins, like calmodulin and S100 proteins, are considered to exert Ca(2+)-dependent actions in the nucleus or the cytoplasm. The Ca2+/phospholipid binding proteins are classified into two groups, the annexins and the C2 region proteins. These proteins, distributed mainly in the cytoplasm, translocate to the plasma membrane in response to an increase in cytosolic Ca2+ and function in the vicinity of the membrane. Ca2+ storage proteins in the endoplasmic or sarcoplasmic reticulum provide the high Ca2+ capacity of the Ca2+ store sites, which regulate intracellular Ca2+ distribution. The variety and complexity of Ca2+ signaling result from the cooperative actions of specific Ca(2+)-binding proteins. This review describes biochemical properties of intracellular Ca(2+)-binding proteins and their proposed roles in mediating Ca2+ signaling.

Isolation and characterization of the gene encoding an aminopeptidase involved in the selective toxicity of ascamycin toward Xanthomonas campestris pv. citri

An aminopeptidase gene named XAP has been isolated from Xanthomonas campestris pv. citri, a plant pathogenic bacterium. The bacterium is one of the rare micro-organisms susceptible to ascamycin, an aminoacyl nucleoside antibiotic that inhibits protein synthesis. Sequence analysis reveals that the gene encodes a 311 amino acid protein with a calculated molecular mass of 35134 Da and approx. 50% identity for amino acids to the proline iminopeptidase from Neisseria gonorrhoeae. The XAP gene product, Xap, expressed in Escherichia coli has proline iminopeptidase activity as well as ascamycin dealanylating activity in vitro.

Granulocyte-colony stimulating factor and stem cell factor are the crucial factors in long-term culture of human primitive hematopoietic cells supported by a murine stromal cell line

The findings that murine marrow stromal cell line MS-5 supported the proliferation of human lineage-negative (Lin-) CD34+CD38- bone marrow cells in long-term culture have been reported. In this study, we analyzed this proliferating activity of MS-5-conditioned medium (CM) on human primitive hematopoietic cells. When Lin-CD34+CD38- cells of normal human cord blood cells were co-cultured with MS-5, colony forming cells (CFCs) were maintained over 7 weeks in vitro. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using membrane filter (0.45 micron) was negligible for this activity. This indicated that the activity of MS-5 on human primitive hematopoietic cells is a soluble factor(s) secreted from MS-5, which is not induced by the contact between MS-5 and Lin-CD34+CD38- cells. We tried to purify this soluble activity. An active material with a molecular weight of about 150 kDa, determined by gel filtration chromatography, solely supported the growth of Lin-CD34+CD38- cells and Mo7e, a human megakaryocytic cell line. This activity not only reacted with anti-mouse stem cell factor (mSCF) antibody on Western blots, but it was also neutralized in the presence of anti-mSCF antibody. Another active material with a molecular weight of about 20-30 kDa synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed to do so alone, although this synergy was inhibited in the presence of soluble mouse granulocyte-colony stimulating factor (mG-CSF) receptor, which is a chimeric protein consisting of the extracellular domain of mG-CSF receptor and the Fe region of human IgG1. In addition, the latter molecule supported the growth of the G-CSF dependent cell line FD/GR3, which is a murine myeloid leukemia cell line, FDC-P2, transfected with mG-CSF receptor cDNA. Adding of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-CM. Recombinant (r) mSCF and rmG-CSF had synergistic activity on the growth of Lin-CD34+CD38- cells. These results indicated that the activity on Lin-CD34+CD38- cells included in MS-5-CM is based upon the synergistic effects of mSCF and mG-CSF.

Isoform-specific intracellular vesicle formation by recombinant annexin XI-A in Sf9 cells

Annexins are a group of structurally related proteins that bind phospholipids in a Ca2(+)-dependent manner and have the ability to self-aggregate and to promote vesicle aggregation and membrane fusion. Two isoforms of annexin XI, termed XI-A and XI-B, were previously identified by screening a bovine chondrocyte cDNA library. But little is known about differences in their biological function. In the present study, we therefore examined the results of expression of the two proteins in Spodoptera frugiperda (Sf9) insect cells, and in mammalian COS-7 cells. Annexin XI isoforms were expressed in Sf9 cells using a baculovirus expression system. Recombinant annexin XI-A but not XI-B caused formation of spherical "annexin XI-associated vesicles, " in the cytoplasm of Sf9 cells. Furthermore, indirect immnocytofluorescence studies showed similar phenomenon, that of local aggregation, with transfected annexin XI-A in COS-7 cells, whereas annexin XI-B remained diffusely distributed throughout the cytoplasm. Since annexin XI isoforms differ in amino acid sequence only in the alternative splicing region of the N-terminal domain, these findings suggest that this domain has distinct biological significance in terms of aggregation and vesicle formation.

Suppression by IL-10 and IL-4 of cytokine production induced by two-way autologous mixed lymphocyte reaction

The immune response of T cells to self-HLA antigens on autologous non-T cells is known as the autologous mixed lymphocyte reaction (AMLR), and is defective in various diseases. We have investigated the effects of exogenous IL-10, a potential agent to treat various inflammatory diseases, on cytokine production induced by two-way AMLR in human peripheral blood mononuclear cells (PBMC). Effects of exogenous IL-4 were also investigated. IL-10 suppressed IL-6, IL-8, TNF-alpha and GM-CSF production when added at the beginning of culture and added 24 h after incubation. It abolished IL-1 alpha production only when added at the beginning of culture. IL-10 did not inhibit IL-3 production. The pattern of suppression by IL-10 of cytokine production induced by anti-CD3 mAb or PHA was similar to that induced by AMLR. Although IL-4 showed a largely similar pattern of inhibition when added at the beginning of culture, the level of inhibition was much lower than that of IL-10. IL-4 did not inhibit cytokine production when added 24 h after culture. These results indicate that IL-10, but not IL-4, is a potent inhibitor to cytokine production induced by two-way AMLR.

Association between the DRB1*08032 histocompatibility antigen and methimazole-induced agranulocytosis in Japanese patients with Graves disease

OBJECTIVE

To determine the association between HLA class II genes and methimazole-induced agranulocytosis in patients with Graves disease.

DESIGN

Case-control study.

SETTING

Kuma Hospital, which specializes in thyroid diseases, in Kobe, Japan.

SUBJECTS

24 patients with Graves disease who had methimazole-induced agranulocytosis diagnosed by peripheral granulocyte counts of less than 0.5 x 10(9)/L, and 68 patients with Graves disease treated with methimazole, who were free from agranulocytosis. Controls were 525 healthy, unrelated Japanese student volunteers at Kyushu University in Japan.

MEASUREMENTS

All HLA class II genes were analyzed for polymorphisms at the DNA level by using the polymerase chain reaction sequence-specific oligonucleotide probes method. The allele frequencies in the agranulocytotic Graves disease group were compared with those in the nonagranulocytotic Graves disease and control groups.

RESULTS

A strong positive association was seen in DRB1*08032 between the agranulocytotic group and both the control and nonagranulocytotic Graves disease groups.

CONCLUSION

The HLA DRB1*08032 allele was strongly associated with susceptibility to methimazole-induced agranulocytosis, suggesting that cellular autoimmunity may be involved in its development.

Functional hierarchy of c-kit and c-fms in intramarrow production of CFU-M

Whereas the molecular natures of M-CSF/CSF-1 and its receptor c-fms are well characterized, its actual role in the intramarrow hematopoiesis remains obscure. This is because disruption of this signaling pathway results in the osteopetrosis mouse that lacks the bone cavity for hematopoiesis. To elucidate the role of c-fms in intramarrow hematopoiesis, we produced an antagonistic monoclonal antibody to murine c-fms and investigated its expression and function in the normal bone marrow. c-fms+ cells were detected both in mature and immature hematopoietic cells. Morphologically, c-kit+c-fms-, c-kit+c-fms+ and c-kit-c-fms+ cells were medium sized blasts, large promyelocytes with azurophilic granules and mature monocytes respectively. CFU-M was 10-fold more enriched in the c-kit+c-fms- than c-kit+c-fms+ fraction. Moreover, injection of the anti c-fms antibody had no effect on the production of CFU-M in the bone marrow, while anti-c-kit mAb could deplete them. As c-kit+c-fms+ cells were readily generated in the culture of c-kit+c-fms- cells, most of the CFU-M in the bone marrow are, in fact, c-fms- cells that differentiate into c-fms+ upon culture. These observations indicate a clear functional hierarchy of c-kit and c-fms in the bone marrow. Namely, c-kit plays the primary role in the production and maintenance of CFU-M, while c-fms, though it co-expressed with c-kit and functions as the growth receptor for M-CSF in the culture, has only a minimum role in the proliferation of c-fms+ cells in the bone marrow.

Clinical characteristics of subacute thyroiditis classified according to human leukocyte antigen typing

We investigated human leukocyte antigen (HLA) class I and class II antigens in 56 Japanese patients with subacute thyroiditis (SAT) who visited our out-patient clinic between 1988 and 1990. We found SAT to be associated with not only HLA-B35 (40 patients; P < 0.000001; relative risk, 18.02), but also with HLA-B67 antigens (9 patients; P < 0.00001; relative risk, 11.20). No heterozygotes of HLA-B35 or HLA-B67 were found in any of the 56 patients with SAT. Either HLA-B35 or HLA-B67 antigen is found in 87% of patients with SAT. When season of onset and clinical course of SAT were compared in the 49 patients with HLA-B35-positive SAT (B35-SAT) and HLA-B67-positive SAT (B67-SAT), we were able to identify certain characteristics: 1) B67-SAT often followed the course from transient thyrotoxicosis to a hypothyroid phase to a euthyroid phase [6 of 9 B67-SAT (67%) vs. 10 of 40 B35-SAT (25%); P < 0.05]; and 2) B67-SAT occurred mostly during the summer or autumn and at a higher rate than did B35-SAR [8 of 9 B67-SAT (89%) vs. 17 of 40 B35-SAT (43%)], whereas B35-SAT occurred throughout the year. We conclude that there are at least two types of SAT that can be classified by association with either HLA-B35 or HLA-B67 antigens.

Differences in MHC class I self peptide repertoires among HLA-A2 subtypes

To investigate how single amino acid substitutions in MHC class I molecules affect differences in peptide repertoires, we eluted and sequenced the naturally processed peptides from three HLA-A2 subtypes (HLA-A*0204, -A*0206, and -A*0207) that differ by a single amino acid residue substitution each with HLA-A*0201 at the floor of the binding groove. Allele-specific peptide motifs for each HLA-A2 subtype substantially differed from that of HLA-A*0201 in the dominant anchor residues. The relative signal intensities for 18 self peptides, determined by mass spectrometry, precisely reflected these peptide motifs. Some overlapping peptides were isolated from both HLA-A*0201 and a single HLA-A2 variant, but no peptide was ubiquitously found across all variants. To rationalize the differences in peptide motifs, possible conformations of each allele were computer modeled by energy minimization calculations based on the reported crystal structure of HLA-A*0201. According to our models, the differences in peptide motifs could be explained by substituted-residue-driven conformational changes for each MHC-peptide complex. These results demonstrate the fine differences between HLA-A2 subtype self peptide repertoires and contribute to the prediction of antigenic peptides.

Differences in MHC class I self peptide repertoires among HLA-A2 subtypes

To investigate how single amino acid substitutions in MHC class I molecules affect differences in peptide repertoires, we eluted and sequenced the naturally processed peptides from three HLA-A2 subtypes (HLA-A*0204, -A*0206, and -A*0207) that differ by a single amino acid residue substitution each with HLA-A*0201 at the floor of the binding groove. Allele-specific peptide motifs for each HLA-A2 subtype substantially differed from that of HLA-A*0201 in the dominant anchor residues. The relative signal intensities for 18 self peptides, determined by mass spectrometry, precisely reflected these peptide motifs. Some overlapping peptides were isolated from both HLA-A*0201 and a single HLA-A2 variant, but no peptide was ubiquitously found across all variants. To rationalize the differences in peptide motifs, possible conformations of each allele were computer modeled by energy minimization calculations based on the reported crystal structure of HLA-A*0201. According to our models, the differences in peptide motifs could be explained by substituted-residue-driven conformational changes for each MHC-peptide complex. These results demonstrate the fine differences between HLA-A2 subtype self peptide repertoires and contribute to the prediction of antigenic peptides.

Terminal differentiation of murine resident peritoneal macrophages is characterized by expression of the STK protein tyrosine kinase, a receptor for macrophage-stimulating protein

STK, a new member of the hepatocyte growth factor receptor family, is the receptor for macrophage-stimulating protein (MSP), which acts on murine resident peritoneal macrophages. We established polyclonal and monoclonal antibodies against STK and characterized the structure of STK protein and STK expression on cells of the mononuclear phagocyte system. Western blotting showed that the STK transcript is translated into a single-chain precursor and then cleaved into a 165-kD disulfide-linked heterodimer composed of a 35-kD alpha-chain and a 144-kD beta-chain. Western blotting detected STK protein on resident peritoneal macrophages, a target of MSP, and showed that it was autophosphorylated in cells stimulated by MSP. By flow cytometric analysis using a monoclonal anti-STK antibody, we showed that STK protein is expressed on restricted macrophage populations such as resident peritoneal macrophages, but not on exudate peritoneal macrophages or mononuclear phagocytes of the bone marrow, peripheral blood, spleen, or alveoli. Resident peritoneal macrophages were classified into two fractions according to their reactivity with an anti-STK antibody and a marker antibody for macrophages: STKhigh-F4/80high cells and STKnegative-F4/80low cells. Acute exudative macrophages were all STKnegative-F4/80low, but they gradually became predominantly STKhigh-F4/80high several days after entrance into the peritoneal cavity. These results showed that after monocytes migrate into the peritoneal cavity, they undergo terminal differentiation in the peritoneal microenvironment. This is the first evidence of tissue-specific terminal differentiation of peritoneal macrophages, and this terminal differentiation can be characterized by the expression of STK receptor tyrosine kinase.

RK-682, a potent inhibitor of tyrosine phosphatase, arrested the mammalian cell cycle progression at G1phase

A specific inhibitor of protein tyrosine phosphatase (PTPase), RK-682 (3-hexadecanoyl-5-hydroxymethyl-tetronic acid) was isolated from microbial metabolites. In vitro, RK-682 inhibited dephosphorylation activity of CD45 and VHR with IC50 54 and 2.0 microM, respectively. In situ, sodium orthovanadate and RK-682 enhanced the phosphotyrosine level of Ball-1 cells, a human B cell leukemia, but not the phosphoserine/threonine level. The PTPase inhibitors, however, had the different arrest point on the cell cycle progression. Sodium orthovanadate inhibited the cell cycle progression at G2/M boundary phase, on the other hand, RK-682 inhibited the G1/S transition.

Hematopoietic stem cells found in lineage-positive subsets in the bone marrow of 5-fluorouracil-treated mice

It is known that treatment of mice with 5-fluorouracil (5-FU, 150 mg/kg) confers radioprotection. To investigate this effect, we performed bone marrow transplantation (BMT) using C57BL/6-Ly5 congenic mice treated with 5-FU five days prior to experiments. The mononuclear cells (MNC) in 5-FU-treated bone marrow (BM) were 10 times more radioprotective than those in untreated BM. Moreover, the number of BM MNC expressing c-kit on their surface from 5-FU-treated mice was markedly decreased relative to those from untreated controls. These results showed that the surface characteristics of cells that contributed to this radio-protective effect differ from those of stem cells as reported recently. BM MNC of mice treated with 5-FU were separated on the basis of expression of the lineage-specific antigens (Lin), c-kit, and Ly6A/E. When injected into lethally irradiated mice, 1,000 Lin+ and Lin-c-kit+Ly6A/E+ cells showed radioprotective effects such that 100% and 60% survived, respectively. Flow cytometric analysis 165 days after BMT showed that 88.8% and 65.1% of peripheral blood (PB) in mice transplanted with Lin+ and Lin-c-kit+Ly6A/E+ was derived from donor mice, respectively. After six months, donor-derived Lin-c-kit+Ly6A/E+ cells which showed radioprotective effects on a secondary irradiated host were detected from mice transplanted with Lin+ cells from 5-FU-treated mice. Taken together, these findings demonstrated that stem cells expressing Lin+ present in the BM of mice treated with 5-FU other than Lin-c-kit+Ly6A/E+ cells and these Lin+ cells play an important role in the recovery of myeloablative mice.

The rat neutrophil low-affinity Fc receptor for IgG: molecular cloning and functional characterization

A complementary DNA (cDNA) clone encoding rat Fc gamma receptor II (Fc gamma RII) was isolated from rat neutrophils and characterized. The cDNA encodes a type I transmembrane protein with 285 amino acids having an extracellular domain consisting of two immunoglobulin-like domains (179 amino acids), a transmembrane domain (26 amino acids), and a cytoplasmic domain (47 amino acids). The nucleotide sequences are identical to that of recently cloned Fc gamma RII from rat mast cells. This protein was expressed on FcR-negative Chinese hamster ovary (CHO) cells. The characterization of cDNA-transfected CHO cells clearly indicated that the protein encoded by the cDNA clone binds guinea-pig IgG1 and IgG2 complexes and unexpectedly binds monomeric rat IgG1, but not IgG2. Furthermore, the affinity for immune complexes was significantly augmented by protease treatment of transfectants. In addition, endocytosis of immune complex was noted in transfectants.

Identification and minisatellite linkage analysis of SMXA recombinant inbred strains of mice by DNA fingerprinting

SMXA recombinant inbred (RI) strains of mice were produced by systematic inbreeding from the F2 generation of a cross between two progenitor inbred strains, A/J and SM/J, which differ considerably with respect to many characteristics, and consists of 28 inbred strains. In this study, we investigated the applicability of DNA fingerprinting with M13 phage DNA to the identification of these closely related strains. DNA fingerprints of the SMXA RI strains and their progenitors, SM/J and A/J, showed strain-specific patterns, with the same banding patterns within each strain. Linkage analysis by using strain distribution patterns of minisatellite loci with 108 genetic markers containing microsatellites, biochemical and immunological marker genes allowed 23 minisatellite loci to be assigned to 11 chromosomes. The results suggested that DNA fingerprinting with M13 phage DNA is applicable not only for strain identification but also for genetic monitoring of RI strains on almost all chromosomes.

RP105, a novel B cell surface molecule implicated in B cell activation, is a member of the leucine-rich repeat protein family

The RP105 Ag is a murine B cell surface molecule that transmits an activation signal into B cells following ligation with anti-RP105 mAb. The activation leads to protection of B cells from irradiation- or dexamethasone-induced apoptosis, and to B cell proliferation. A cDNA encoding the RP105 Ag was isolated. An encoded protein is a type I transmembrane protein consisting of 641 amino acids in a mature form. Northern hybridization with a probe specific for the cDNA clone detected a transcript with a size of approximately 3 kb. The transcript was observed in spleen, but not in thymus, kidney, muscle, heart, brain, or liver. Stable transfection of the cDNA clone conferred the expression of the RP105 Ag on a pro-B cell line, which was confirmed by immunofluorescence staining and immunoprecipitation with anti-RP105 mAb. The RP105 molecule possesses 22 tandem repeats of a leucine-rich motif. These repeated motifs are observed in members of the leucine-rich repeat protein family, and have been implicated in protein-protein interactions, such as cell adhesion or receptor-ligand binding. Amino- and carboxyl-flanking regions that are characteristically conserved among members of the family are located on both sides of tandemly repeated leucine-rich motifs in RP105 molecule. These results demonstrate that RP105 is a novel member of the leucine-rich repeat protein family, and the first member that is specifically expressed on B cells.

RP105, a novel B cell surface molecule implicated in B cell activation, is a member of the leucine-rich repeat protein family

The RP105 Ag is a murine B cell surface molecule that transmits an activation signal into B cells following ligation with anti-RP105 mAb. The activation leads to protection of B cells from irradiation- or dexamethasone-induced apoptosis, and to B cell proliferation. A cDNA encoding the RP105 Ag was isolated. An encoded protein is a type I transmembrane protein consisting of 641 amino acids in a mature form. Northern hybridization with a probe specific for the cDNA clone detected a transcript with a size of approximately 3 kb. The transcript was observed in spleen, but not in thymus, kidney, muscle, heart, brain, or liver. Stable transfection of the cDNA clone conferred the expression of the RP105 Ag on a pro-B cell line, which was confirmed by immunofluorescence staining and immunoprecipitation with anti-RP105 mAb. The RP105 molecule possesses 22 tandem repeats of a leucine-rich motif. These repeated motifs are observed in members of the leucine-rich repeat protein family, and have been implicated in protein-protein interactions, such as cell adhesion or receptor-ligand binding. Amino- and carboxyl-flanking regions that are characteristically conserved among members of the family are located on both sides of tandemly repeated leucine-rich motifs in RP105 molecule. These results demonstrate that RP105 is a novel member of the leucine-rich repeat protein family, and the first member that is specifically expressed on B cells.