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Biomedical subjects

N Kamada

Publications and source records attributed to N Kamada.

At least 181 records · Page 10Linked to original sources
PubMed1994

The induction of immediate early genes in postischemic and transplanted livers in rats. Its relation to organ survival.

The protein products of the immediate early genes (IEG)s have been proposed to play an important role in long-term tissue plasticity such as cell repair or programmed cell death. The expression of liver IEGs was studied following liver ischemia (LI) or OLT in rats. In LI, 60 min of warm ischemia was induced in shunted rats (shunt LI group; 100% survival) and nonshunted rats (nonshunted LI group; poor survival). In OLT, donor livers were transplanted into the recipients within 1 hr (fresh liver OLT group; 100% survival) or after 24 hr of storage using University of Wisconsin solution (preserved liver OLT group; poor survival). Using both models, IEG mRNAs (c-fos and c-jun) were analyzed by Northern blot hybridization at various times before and after reperfusion. The expression of liver IEGs was not induced by warm ischemia and cold preservation alone. Reperfusion of livers following warm ischemia or cold preservation resulted in a distinctly different pattern of gene expression in viable and nonviable livers. In shunted LI and fresh liver OLT groups (viable), c-fos and c-jun mRNAs increased markedly to a peak value within 1-2 hr of reperfusion, returning to basal level by 3 hr. In nonviable livers, the level of these mRNAs was detected continuously at 3 hr of reperfusion in the nonshunted LI model and also at 6 hr after reperfusion in the preserved liver OLT group. Our data suggest that a protracted pattern of expression of c-fos and c-jun in the liver at the early stage of reperfusion might be correlated with the severity of liver transplant-related insults and subsequent graft failure.

Animals↗
PubMed1994

Morphometric analysis of infiltrating cells that adhere to the sinusoidal wall and migrate into the space of disse in the orthotopically transplanted rat liver.

To reveal the kinetics of infiltrating cells in the hepatic parenchyma after the liver transplantation, we identified the cell type (macrophages, monocytes, agranular lymphocytes, large granular lymphocytes, and neutrophils) and localization on toluidine blue-stained sections of perfusion-fixed liver grafts in rejecting and tolerant combinations and performed quantitative analysis of the density of each cell species infiltrating inside and outside the sinusoid at days 4 and 7. The number of total infiltrating cells per unit square became 9 times as high as that of an untreated liver at day 4 and 30 times as high at day 7. Macrophages accounted for a large part of the infiltrating cells both in and around the sinusoid: 72% of intrasinusoidal infiltrating cells and 88% of extrasinusoidal ones at day 4; 73% of intrasinusoidal ones and 93% of extrasinusoidal ones at day 7. The ratio of extrasinusoidal cell to intrasinusoidal cell of macrophages was 9:91 at day 4 and 34:66 at day 7, much higher than ratios of other infiltrating cells. This fact means that macrophages show a marked tendency to migrate out of the sinusoid in the liver graft. The proportion of macrophages to total infiltrating cells dropped at day 4 and went up again at day 7, while that of monocytes showed a reverse pattern. Histologically, immature macrophages, possibly derived from recipient monocytes, coexisted with vacuolated donor macrophages in the sinusoid at day 4, but the latter cells were diminished at day 7. These data indicate that transformation of recipient monocytes into macrophages in the sinusoid and subsequent extrasinusoidal migration of newly formed macrophages occur soon after the cell influx into the liver graft begins at day 4. The present study has revealed that macrophages, especially those migrating into the space of Disse, will be closely related to the pathogenesis of the liver transplantation.

Animals↗
PubMed1994

A reverse transcriptase-polymerase chain reaction detects heterogeneous chimeric mRNAs in leukemias with 11q23 abnormalities.

The MLL gene involved in 11q23 translocations found in the majority of infantile leukemias and some secondary leukemias makes fusion transcripts with genes such as LTG4 (chromosome 4), LTG9 (chromosome 9), and LTG19 (chromosome 19) as a result of reciprocal translocation. We have examined 25 cases of leukemias with 11q23 abnormalities by Southern blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR). Using various primer pairs, chimeric mRNAs could be amplified in 6 of 7 leukemias with t(4;11), 6 of 8 leukemias with t(9;11) including secondary leukemia, 8 of 9 leukemias with t(11;19), and 1 with a deletion at 11q23. The chimeric mRNAs were heterogeneous and differential usage of the MLL exons was found, irrespective of the partner chromosomes. Sensitivity studies showed that a single clone with chimeric mRNA in 10(4) to 10(5) cells could be detected. These findings show that the present RT-PCR settings provide a rapid, accurate, and sensitive tool for diagnosing leukemias with 11q23 translocations and for monitoring response to therapy in these patients.

Adult↗
PubMed1994

A technique for complete thymectomy in adult rats.

50 open thymectomies were performed in adult rodents using intubation combined with a fibrin glue able to prevent hemorrhage and pulmonary air leakage. This method had a 100% success rate and lower mortality than the ordinal suction procedure. Although the conventional suction thymectomy has been widely used, the open thymectomy method would permit more complete thymectomies for immunological studies.

Animals↗
PubMed1994

Elevated blood pressure and craniofacial abnormalities in mice deficient in endothelin-1.

The endothelin-1 (ET-1) gene was disrupted in mouse embryonic stem cells by homologous recombination to generate mice deficient in ET-1. These ET-1-/- homozygous mice die of respiratory failure at birth and have morphological abnormalities of the pharyngeal-arch-derived craniofacial tissues and organs. ET-1+/- heterozygous mice, which produce lower levels of ET-1 than wild-type mice, develop elevated blood pressure. These results suggest that ET-1 is essential for normal mouse development and may also play a physiological role in cardiovascular homeostasis.

Animals↗
PubMed1994

Portosystemic shunt for orthotopic liver transplantation in the rat.

Despite several technical improvements, orthotopic liver transplantation (OLT) in the rat remains the most difficult experimental microsurgical transplant to perform. The short anhepatic phase tolerated by the rat makes it difficult for beginners to perform the suprahepatic and portal vein anastomoses in the limited time available. To overcome this obstacle, we examined the ability of a portosystemic shunt, induced previously by subcutaneous transposition of the spleen (STS), to decompress the portal system during hepatic pedicle clamping and thus prolong the anhepatic phase of OLT in the rat. Effective drainage was shown by the ability of rats subjected to STS 3 weeks previously to survive portal pedicle clamping of 120 min, while normal rats all died after 90 min of clamping. We demonstrated that, in STS rats, OLT performed with an anhepatic phase of 1 hr had 100% survival at 1 week, while this procedure caused 100% death in normal rats. The ablation in STS rats of the drastic pH decrease and appearance of endotoxins seen in the portal blood of normal rats subjected to "OLT-like" clamping corroborated these results. This application of the STS model to the field of OLT has already proved in our laboratory to be extremely useful during the surgical learning phase of liver transplantation in the rat.

Animals↗
PubMed1994

Effect of granulocyte colony-stimulating factor on neutropenia in liver transplant recipients with hypersplenism.

The authors present details of their initial experience with use of recombinant human granulocyte colony-stimulating factor (rhG-CSF) for preventing neutropenia caused by hypersplenism, and, possibly, for reducing the risk of postoperative infections in pediatric liver transplant recipients. Seven patients with end-stage liver disease, three of whom had severe hypersplenism, underwent living related liver transplantation (LRLT). The rhG-CSF was administered to the latter three patients. Peripheral neutrophil counts decreased immediately after reperfusion (to 1500 +/- 300/microL) in the three patients, and returned to normal with use of rhG-CSF 3 to 10 days after transplantation. The dosage was adjusted to maintain peripheral leukocyte and granulocyte counts above 5,000/microL and 2,000/microL, respectively. This initial clinical trial showed that rhG-CSF administration restores the leukocyte counts of patients who have hypersplenism, without any significant adverse effects, and that rhG-CSF holds promise for reducing the risk of infections after liver transplantation.

Child↗
PubMed1994

Small bowel transplantation for pediatric short bowel syndrome: evaluation of the graft length required for development and the immunologic aspects relating to graft length.

Small bowel transplantation (SBT) is thought to be the only radical treatment for short bowel syndrome in childhood. It is very important that the length of the graft and the type of intestine be chosen carefully because this will determine the outcome of transplantation. This model of short bowel syndrome in the rat confirms that total intestinal resection results in malnutrition and failure to gain weight. After 10 cm of ileum was transplanted orthotopically in a syngeneic combination in rats with total intestinal resection, the animals gained weight. The authors determined that 10 cm of terminal ileum is the minimum length required for survival. Second, the immunologic basis of lethal graft-versus-host reaction (GVHR) as it relates to the intestinal graft length was also evaluated. Ileal grafts of 10 cm from LEW (RT1l) rats were implanted heterotopically into (LEW x BN)F1 rats. Ileal grafts of 10 or 40 cm were implanted from BN(RT1n) rats into (LEW x BN)F1 animals. A lethal GVHR always occurred after grafting a 10 cm ileum in the LEW/F1 combination, whereas only 17% of the BN/F1 recipients died of typical GVHR. However, in the latter combination, 67% lethal GVHR was induced when 40 cm of the intestinal graft was implanted. These results indicate that mesenteric lymph nodes are a major source of lethal GVHR, but gut-associated lymphoid tissue can also induce this.

Animals↗
PubMed1994

Effects of 252Cf neutrons, transmitted through an iron block on human lymphocyte chromosome.

Chromosome aberration of human peripheral blood lymphocytes exposed to californium-252 (252Cf) neutrons transmitted through a 15 cm thick iron block was analysed. The spectrum of the filtered neutrons ranged from 0.1 to 2 MeV with a peak at 0.7 MeV, simulating the Hiroshima atomic bomb neutron spectrum as shown in the Dosimetry System 1986 (DS86). Chromosome aberration frequencies after exposure to filtered and unfiltered 252Cf radiation were compared. Acentric ring chromosomes were significantly increased (p < 0.05) in the filtered condition. However, yields of dicentrics and centric rings induced by the filtered neutrons were not statistically different from those induced by the unfiltered neutrons (p > 0.1). The relative biological effectiveness (RBE) of the neutrons with respect to the formation of dicentrics and centric rings was 10.9 and 12.3 in the filtered and unfiltered conditions respectively, but the difference was not statistically significant. These results provide useful information for the re-evaluation of the biological effect of the Hiroshima atomic bomb radiations.

Californium↗
PubMed1994

Prevention by liver transplantation of the graft-versus-host reaction and allograft rejection in a rat model of small bowel transplantation.

In the rat combination of DA (MHC haplotype RT1av1) donor into PVG(RT1c) recipient, liver grafts are not rejected and allow the acceptance of other organ grafts from the same donor strain. Here we show that an existing DA liver graft allows the acceptance of a DA small bowel graft in the PVG; the liver graft also prevented the graft-versus-host reaction normally associated with small bowel grafting. In addition, a liver graft could suppress the GVHR in F1 hybrid recipients of parental lymphoid cells, a classic GVHR model. GVHR suppression was immunologically specific and required that donor lymphocytes and liver be of the same strain. Besides their clinical implications, these results demonstrate the capacity of the liver for tolerance induction and suggest that it may play a physiological role in negative selection of T cells.

Animals↗
PubMed1994

Telomere reduction of specific chromosome translocation in acute myelocytic leukemia.

The length of telomere restriction fragments (TRF) was studied by Southern blotting in 42 patients with acute myelocytic leukemia (AML) including 15 patients with 8;21 translocation, 8 with 15;17 translocation and 19 with a normal karyotype. The TRF length of leukemic cells with a normal karyotype and with 8;21 or 15;17 translocation showed significant reduction compared to that of lymphocytes from normal individuals (P < 0.05). In addition, there was a statistically significant difference in TRF length between leukemic cells with a normal karyotype and 8;21 translocation (P < 0.05). Therefore, the significant difference of telomere reduction in 8;21 translocation may be an important factor in the leukemogenic process.

Adolescent↗
PubMed1994

Characteristics of human hepatocellular carcinoma cell lines (Hep-KANO) derived from a non-hepatitic, non-cirrhotic hepatitis B virus carrier.

We have established two cell lines of hepatocellular carcinoma [Hep-KANO, clone 1 (CL-1) and clone 2 (CL-2)] from tissue obtained at autopsy of a hepatitis B virus (HBV) carrier without histological signs of hepatitis or liver cirrhosis. These cell lines differed considerably from each other in morphology, proliferation pattern, alpha-fetoprotein secretion, albumin synthesis, cytokine secretion, modal chromosome number and transplantability to nude mice. Histologic examinations also revealed differences between them. Amplification of N-myc, L-myc, H-ras, K-ras, N-ras, c-erb-B and c-erb-B-2 and rearrangement of p53 were not found in either of the cell lines. However, CL-1 and CL-2 showed an identical HBV-DNA integration pattern. A 4-fold amplification of c-myc was observed in CL-1, but not in CL-2. Hep-KANO cell lines, CL-1 and CL-2 may be useful in clarifying the question of whether hepatocarcinogenesis is directly caused by HBV infection.

Adult↗
PubMed1994

Efficacy of prostacyclin analogue (OP-2507) in viable hepatic grafts from pigs with non-beating hearts.

We investigated whether the stable prostacyclin analogue (OP-2507; OP) would ameliorate warm ischemia-related injury of the liver graft under conditions of a nonbeating heart. Thirty-six mongrel pigs were arranged into 3 groups of 6 pairs. Group 1 pigs underwent orthotopic liver transplantation from heart-beating donors (HBD). In group 2, animals received liver grafts from nonheart-beating donors (NHBD), defined as 30 min of cardiac arrest. Group 3 pigs received grafts from NHBD, but the donor had been pretreated with OP by intraportal infusion (2 microg/kg x min for 30 min immediately before the induction of cardiac arrest). The grafts were preserved at 4 degrees C in Euro-Collins solution in which OP was dissolved at 200 microg/l. Five-day survival rates after transplantation improved significantly in OP-treated animals (3/6, for group 3), compared with 0/6 for group 2 (P < 0.05, generalized Wilcoxon test). Five of 6 animals survived more than 5 days in the HBD group (group 1). Although the serum transaminase activities and bile production did not differ in the early phase of recirculation among the groups, there was a significant improvement in the hepatic microcirculatory environment in the surviving groups (groups 1 and 3). Analysis of arterial prostanoid levels showed a substantial suppression of PGE2 release by OP treatment following reperfusion. Our data indicate that a stable prostacyclin analogue can be clinically useful for expanding the donor pool by improving the quality of the liver graft.

Animals↗
PubMed1994

Successful methods of pancreas transplantation in the rat using a cuff technique.

Two models of pancreas transplantation were examined in the rat with a view to choosing one for regular use in functional experiments. A cuff technique applied to the renal vessels of the recipient was used. The histology and endocrine functioning of whole pancreas-duodenal transplant (Tx) plus bladder drainage (drainage model), and the pancreatic duct ligated segmental pancreas Tx (ligated model) were examined. Syngeneic operations were performed using either Lewis or Wistar rats. Streptozotocin (STZ) 60 mg/kg intravenously (i.v.) was used to render the recipient rats diabetic. A cuff technique was used with both models to anastomose the grafts to the renal vessels instead of the conventional technique of hand suturing to the abdominal vessels. This allows a shorter warm ischaemia time for the donor pancreas and leaves the systemic circulation intact leading to a high success rate for both techniques. Operation survival rates were 93% (n = 30) and 90% (n = 10) in the ligated and drainage models, respectively. The recipients in both groups were normoglycaemic for > 100 days. Histological examination revealed atrophic exocrine tissue early in the ligated group but only two from the drainage group showed exocrine atrophy at > 100 days. There was no statistical difference in i.v. glucose tolerance tests with both models showing a normal pattern. Thus, endocrine function remained independent of exocrine function. Both models are quicker than the conventional techniques. The duct ligation model was a simpler transplant to perform, suggesting that this should be the technique of choice in future experiments.

Anastomosis, Surgical↗
PubMed1994

Cellular characteristics of acute myeloblastic leukemia associated with t(8;21)(q22;q22). The Japanese Cooperative Group of Leukemia/Lymphoma.

A large number of AML cases is reviewed in order to clarify biological characteristics of t(8;21) AML cells. The incidence of positivities for stem cell antigens, CD34 and HLA-DR, on blasts in t(8;21) AML is higher in comparison with those in other M2 or M3 categories. Frequent expression of CD34 and HLA-DR is indicative of the stem cell derivation of t(8;21) AML cells. The non-blastic leukemic cells in t(8;21) AML tend to lose the immature phenotype with discordant maturation such as low CD33 expression. Further, the blasts show frequent expression of the B-cell antigen, CD19, without other B-cell antigens and immunoglobulin gene rearrangements. AML cells with t(8;21) showed poorer response to granulocyte-macrophage colony-stimulating factor (GM-CSF) due to a decreased number of GM-CSF binding sites. The absence of monocytic differentiation in t(8;21) AML cells might represent the abnormal response to growth factors at the bifurcation stage of granulocyte and monocyte differentiation. Recently, breakpoint region genes for the 8;21 translocation in chromosome 8 and 21 have been isolated, 48-50 and have been named AML1 and ETO, respectively. The AML1 gene showed a strong homology with the Drosophila segmentation gene, runt, which is thought to be necessary for the Sex lethal gene expression. Since the GM-CSF receptor alpha chain gene locates in the pseudoautosomal region of the sex chromosome, the decrease of GM-CSF binding sites might be related to the AML1/ETO fusion gene expression. Further molecular genetic investigations of the breakpoint genes in the future are expected to clarify the unique biological events seen in this type of leukemia.

Acute Disease↗
PubMed1994

High frequency of RAS oncogene mutation in chronic myeloid leukemia patients with myeloblastoma.

To determine the role of the mutated RAS oncogene during development into the blast phase, we sequentially analysed RAS oncogene mutations in the bone marrow of 27 patients with chronic myeloid leukemia (CML). DNA from CML patients in chronic and blast phases and nude mouse tumor DNA formed by a tumorigenicity assay (in vivo selection assay) were subjected to the polymerase chain reaction (PCR) and oligonucleotide hybridization. In addition, one patient in the chronic phase and five in the blast phase were also analysed. PCR analysis of DNA from the leukemic patients revealed that 3.6% (1 of 28) and 15.6% (5 of 32) of the patients in the chronic and blast phases, respectively, had RAS mutations. N- or K-RAS oncogene mutations were found mostly in the blast phase (4 of the 5 patients with the RAS oncogene mutation). Of the 5 patients with the RAS oncogene mutation, three developed myeloblastoma, a myeloblast cell tumor, in the blast phase. None of the 28 patients without the RAS mutation developed myeloblastoma. These results suggest that the RAS oncogene mutation occurred in the late stage of the disease and contributed to transformation to the blast phase in some CML patients. The findings also indicate an association between the presence of the RAS mutation and the formation of myeloblastoma.

3T3 Cells↗
PubMed1994

Biological characteristics of a continuous cultured cell line derived from a human malignant fibrous histiocytoma.

A continuous cultured cell line, NATO, was established from a human malignant histiocytoma of bone. The cultured cells consisted of at least 3 types of tumor cells; polygonal, long spindle and occasionally giant cells, which were primarily observed in the original tumor of the patient. Ultrastructurally, they were mostly immature cells that had poorly developed cell organelles and a few lysozomal granules. The cultured cells had phagocytotic activity and were positive for acid phosphatase, transferrin receptor, alpha 1-antitrypsin, alpha-naphthyl acetate esterase and HLA-DR, but negative for Fc- and C3-receptors. Allotransplantation of the cells into athymic nude mice produced tumors at early passages, but did not 3 years later. Four cloned sublines isolated from the parent line also showed essentially an identical morphology with that of the parent cell line, indicating that the 3 cell types were interchangeable.

Animals↗