Biomedical subjects

J Tanaka

Publications and source records attributed to J Tanaka.

At least 289 records · Page 16Linked to original sources

PubMed1997

Preparation and mechanical properties of calcium phosphate/copoly-L-lactide composites.

New artificial bone materials were prepared using calcium phosphates, hydroxyapatite and beta-tricalicum phosphate, and copoly-L-lactide, CPLA. Calcium phosphate powder and CPLA were mixed at 453 K for 10 min with various mixing ratios. Scanning electron microscope observations indicated that the composites of beta-tricalicum phosphate and CPLA were homogeneously dispersed and highly adhesive. Young's modulus of the composites was the same as bone, and bending strength was over half that of bone. The improvement of Young's modulus compared to the original two materials was due to a composite effect. The composites are expected to be usable as artificial bone materials.

Journal Article↗

PubMed1997

Intraductal secretin test is as useful as duodenal secretin test in assessing exocrine pancreatic function.

We assessed the clinical usefulness of the intraductal secretin test in order to ascertain whether it can substitute for the conventional duodenal secretin test. Duodenal juice was obtained with a triple-lumen tube and pure pancreatic juice was obtained by retrograde cannulation of the main pancreatic duct using a duodenofiberscope. Pancreatic secretion was stimulated by a bolus intravenous injection of secretin (100 units). The two tests showed comparable interindividual coefficients of variation, significantly good correlations, and comparable diagnostic efficiencies. The intraductal secretin test showed no less reproducibility than that of the duodenal secretin test as reported in the literature. In the intraductal secretin test, secretory volume, peak flow rate, bicarbonate output, and lipase output yielded the best diagnostic efficiency, followed by amylase output and maximal bicarbonate concentration. In the intraductal secretin test, a 10-min collection provided as much information as a 20-min collection. We conclude, therefore, that the 10-min intraductal secretin test is as useful as the conventional duodenal secretin test in assessing exocrine pancreatic function and that the most discriminatory parameters are secretory volume, bicarbonate output, and amylase (or lipase) output.

Adult↗

PubMed1997

The important balance between cytokines derived from type 1 and type 2 helper T cells in the control of graft-versus-host disease.

We have investigated cytokine mRNA expression in the peripheral blood mononuclear cells of 20 patients who received allogeneic hematopoietic stem cell transplants to assess the cytokine network after transplantation. IL-4 mRNA expression decreased in five of five (100%) patients with > or = grade III (severe) acute GVHD and increased in 10 of 22 (45%) patients without severe GVHD. In contrast, IL-12 mRNA expression increased in two of two (100%) patients with severe GVHD, but increased in only six of 18 (33%) patients without severe GVHD. Furthermore, IL-10 and/or IL-13 mRNA expression increased in 19 of 22 (86%) patients without severe GVHD, but increased in only one of three (33%) patients with severe GVHD. In patients with allogeneic PBSCT who had severe acute GVHD, the cytokine mRNA expression in patients with allogeneic PBSCT, who had no severe GVHD, showed a similar pattern to that in patients with allogeneic BMT. IL-4 mRNA expression increased in three of five (60%) patients and IL-10 and/or IL-13 mRNA expression increased in five of five (100%) patients. In contrast, IL-12 mRNA expression increased in only one of three (33%) patients. Serum IL-4 concentration in allogeneic PBSCT patients in the early engraftment phase was relatively high, while serum IL-12 concentration was low. These findings suggest that severe GVHD may be related to the cytokine imbalance between type 1 helper T (Th1) cells and type 2 helper T (Th2) cells.

Adult↗

PubMed1997

Evidence of brain ischemia in early neonatal sudden death syndrome.

Ten early neonatal sudden death victims (ENSD) were selected for neuropathological and immunohistochemical examinations. The gestational ages of the victims ranged from 36 to 42 weeks, and the postnatal ages from 8 hours to 10 days of life. In 6 of 10 patients, softening with rarefaction was observed in the subcortical or intermediate white matter, which was associated with minimal astrogliosis in the whole white matter. In 7 of the 10 ENSD victims, the number of GFAP-positive glia was significantly greater in both the deep and subcortical white matter than in controls. The brainstem showed mild gliosis in the reticular formation and vagal nuclei of the medulla oblongata in 8 of the 10 ENSD victims. In 8 of the 10 ENSD victims, the number of GFAP-positive astrocytes was greater in both the dorsal vagal nucleus and the reticular formation of the medulla oblongata than in controls. The high incidence of leukomalacia and astrogliosis in the cerebral white matter and brainstem suggests the presence of brain ischemic insults before death, which may be prenatal in some cases.

Astrocytes↗

PubMed1997

Does recurrent acute pancreatitis lead to chronic pancreatitis? Sequential morphological and biochemical studies.

The pathogenesis of chronic pancreatitis (CP) has been debated as to whether it is a de novo process or the consequence of acute pancreatitis (AP). We investigated whether recurrent AP in rats leads to CP, by sequential morphological and biochemical studies. Thirty male Wistar rats were fed a choline-deficient diet with intraperitoneal ethionine injections twice daily at a dose of 60 mg/100 g body weight twice weekly, and six rats were killed at 4, 6, and 8 weeks; the remaining 12 rats, followed without further treatment, were killed at 12 and 16 weeks. The pancreata from study and control groups were examined by histology, immunohistochemistry, and bio- and immunoassays. Histologically, moderate to severe intra- and perilobular fibrosis and other CP-like lesions appeared maximally at 8 weeks. Immunohistochemically, the earliest extracellular matrix change was strong fibronectin staining at 4 weeks, with a progressive increase to 8 weeks. Collagens I and III came to show strong, and collagen IV moderate, interstitial staining at 6-8 weeks. These morphological changes, however, returned to nearly normal at 16 weeks. Prolyl hydroxylase was significantly elevated at 4 and 6 weeks and normalized after 8 weeks, with no significant change in collagenase. In conclusion, our results suggest that even severe CP-like lesions induced by recurrent AP are reversible in the absence of persistently elevated prolyl hydroxylase and/or suppressed collagenase. The mechanism regulating these changes remains to be studied further.

Acute Disease↗

PubMed1997

Diminished salt appetite in spontaneously hypertensive rats following local administration of the angiotensin II antagonist saralasin in the median preoptic area.

Previous studies have suggested that angiotensin (ANG) synthesis, receptor activation, or both, in the median preoptic nucleus (MnPO) are responsible for initiating ANG-related salt appetite in normotensive rats. The present study was designed to test whether treatment with saralasin (Sar), an ANG II antagonist, in the MnPO area causes changes in saline (0.3 M NaCl solution) and water intakes in the spontaneously hypertensive rat (SHR), which is known to show greater salt appetite compared to normotensive Wistar-Kyoto (WKY) rats. Treatment with Sar in the MnPO area produced significantly attenuated saline intake, but had no effect on water intake. The results may support the importance of the ANG system in the MnPO area for salt appetite, and suggest that a disorder in the system may cause abnormal salt intake in SHR.

Angiotensin II↗

PubMed1997

Inhaled low-dose nitric oxide for postoperative care in patients with congenital heart defects.

Postoperative pulmonary hypertensive crisis is a major problem that may account for a substantial part of the postoperative mortality and morbidity. We, therefore, evaluated the effect of inhalation of low-dose nitric oxide (NO) on postoperative care in pediatric patients with pulmonary hypertension. We studied 10 infants and children ages 1-108 months (median age, 11 months) with congenital heart disease associated with pulmonary hypertension. The NO and N2 gas mixture was then mixed with varied quantities of air and oxygen and delivered into a respirator instead of an inspiratory tube. Patients were treated with inhaled NO for 38.6 +/- 19.6 h (range 1-200 h). All patients were eventually weaned from high level sedation and respirator. The NO concentration ranged from 2 to 5 parts per million. During NO inhalation patients demonstrated a statistically significant reduction in systolic pulmonary arterial pressure by approximately 26%; from 55 +/- 10 to 41 +/- 20 mm Hg. Inhalation of NO resulted in a significant increase of Pao2 from 110 +/- 16 to 149 +/- 29 mm Hg. A-aDo2 significantly decreased from 284 +/- 27 to 247 +/- 31 mm Hg. In conclusion, we have shown that a low-dose NO inhalation acted as pulmonary vasodilator in patients with preexisting pulmonary hypertension.

Administration, Inhalation↗

PubMed1997

Inflammatory cytokine production enhancement in the presence of lipopolysaccharide after hepatic resection in cirrhotic patients.

Postoperative infection is one of the main factors that affect mortality after hepatic resection, especially in patients with liver cirrhosis. In the pathogenesis of postoperative organ failures complicating endotoxemia or other surgical injuries, inflammatory cytokine has proved to play an important role. We herein report the changes in tumor necrosis factor-alpha, interleukin-1 beta, and granulocyte colony-stimulating factor in production from macrophages/monocytes stimulated with lipopolysaccharide (LPS) after hepatic resection of cirrhotic livers. Seven hepatocellular carcinoma patients with liver cirrhosis who were undergoing limited resection or segmental resection of the liver were examined. Peripheral blood monocytes were separated and incubated with 10 microg/ml LPS, and cytokine release was measured by ELISA before surgery as well as on Postoperative Days (PODs) 1, 3, 7, and 14. Preoperative cytokine production in cirrhotic patients was greater than cytokine production in noncirrhotic controls. Cytokine productivity increased after hepatic resection. TNF-alpha production was 1,846.6 +/- 882.6 pg/ml, 1,947.3 +/- 221.9 pg/ml, 2,486.9 +/- 519.7 pg/ml, and 1,640.2 +/- 416.0 pg/ml on PODs 1, 3, 7, and 14, respectively. The values on all PODs were significantly greater than the healthy control value, and the value on POD 7 was significantly greater than the preoperative value. Interleukin-1 beta and granulocyte colony-stimulating factor production values corroborated this result in general. In conclusion, macrophages/monocytes are primed in cirrhotic patients preoperatively, and they are supposed to carry greater cytokine producing abilities after hepatic resection. When endotoxin spills over in the blood or in the liver after hepatic resection, postoperative hepatic failure could develop as a result of hypercytokinemia.

Aged↗

PubMed1997

Administration of aminoglycosides to hemodialysis patients immediately before dialysis: a new dosing modality.

We describe a new modality for administering aminoglycosides to hemodialysis (HD) patients, namely, a modification of the once-daily regimen which consists of administering the aminoglycosides over 60 min by drip infusion just before each HD session, with a preplanned peak concentration being reached at the beginning of the session and then with a rapidly decreasing concentration being achieved by the start of HD. The area under the concentration-time curve (AUC), i.e., the accumulation of the drug in the body, is thus minimized by this modality. Arbekacin (ABK) was given at a dose of 2 mg/kg of body weight to 10 HD patients infected with methicillin-resistant Staphylococcus aureus (MRSA) for 2 weeks (six sessions in total), resulting in the complete disappearance of MRSA in 5 patients. A high rate of elimination of ABK was attained for each patient while the patient was on HD (range, 0.20 to 0.42 h-1; mean 0.28 +/- 0.08 h-1) by using high-performance dialyzers provided with membranes made of either polymethylmethacrylate, cellulose triacetate (CTA), or ethylene vinyl alcohol. The best results were obtained with the CTA membrane, as revealed by the overall mass transfer coefficient (Ko). The AUC in the simulation model for the variation in the serum ABK concentration in this modality was calculated to be 40% of that of the conventional post-HD dosing modality, suggesting that a much higher dose could be administered to HD patients who receive HD thrice weekly (4 h per session), giving, e.g., 4 mg/kg initially and before the HD sessions, when there is an interval of 68 h from HD session to HD session, and giving 2 mg/kg before the other sessions.

Aged↗

PubMed1997

Invasive pulmonary aspergillosis complicated by subclavian artery occlusion following allogeneic stem cell transplantation.

We describe an unusual case of invasive pulmonary aspergillosis (IPA) complicated by subclavian artery occlusion in a 32-year-old man with severe aplastic anemia, who underwent allogeneic stem cell transplantation. He was severely neutropenic after the conditioning for transplantation, but he had no history of fungal infection. Five days after the transplantation, he developed IPA in the left upper lung, complicated by left subclavian artery occlusion. Extensive chronic graft-versus-host disease, which required the administration of potent immunosuppressants for a long period of time, interfered with the resolution of the IPA.

Adult↗

PubMed1997

Antenatal detection of Meckel-Grüber syndrome in only one dizygotic twin following in vitro fertilization and embryo transfer.

The first case of Meckel-Grüber syndrome in a dizygotic twin pregnancy following in vitro fertilization and embryo transfer is reported. An ultrasound examination at 26 weeks of gestation revealed multiple malformations of the presenting twin: the combination of an occipital encephalomeningocele, bilateral polycystic kidneys and postaxial polydactyly was suggestive of Meckel-Grüber syndrome. Diagnosis was confirmed after birth. The importance of this case is stressed since particular care must be taken to avoid multiple pregnancies in couples at risk undergoing assisted reproduction.

Diseases in Twins↗

PubMed1997

Biphasic effects of D3-receptor agonists, 7-OH-DPAT and PD128907, on the D1-receptor agonist-induced hyperactivity in mice.

Effects of D3-receptor agonists, 7-OH-DPAT and PD128907, on the D1-receptor agonist SKF81297-induced hyperactivity in mice were examined. 7-OH-DPAT and PD128907 significantly suppressed the SKF81297-induced hyperactivity at low doses, but significantly potentiated the hyperactivity at high doses. These D3-agonists alone had no effect on the motor activity. A kappa-receptor agonist that reduces dopamine release had no effect on the SKF81297-induced hyperactivity. These results suggest that lower doses of 7-OH-DPAT and PD128907 may negatively influence the D1-receptor mediated behaviors via post synaptic D3-receptors. On the other hand, higher doses of these compounds may positively influence these behaviors via D2- or D3-receptors.

Analysis of Variance↗

PubMed1997

Suppression by platelet factor 4 of the myogenic activity of basic fibroblast growth factor.

The effect of platelet factor 4 (PF4) on myoblast cultures with or without basic fibroblast growth factor (bFGF) or other growth factors was investigated in the present in vitro experiments, with reference to bFGF binding to myoblast membrane fraction. When PF4 was added to the culture medium 1 day after myoblast cultivation, the nuclei of both myoblasts and myotubes were markedly reduced in number in a dose-dependent manner, whereas the inhibitory effect of PF4 on myoblast development was not observed when PF4 was added to the culture medium 3, 7, or 14 days after myoblast cultivation. In contrast, bFGF significantly increased the numbers of myoblast and myotube nuclei. When bFGF and PF4 were simultaneously added to the culture medium, PF4 abolished the facilitatory effects of bFGF on myogenesis. The real-time biospecific interaction analysis (BLA) core system showed that the myoblast membrane fraction at 1 day after cultivation contains bFGF-binding elements which are blocked by PF4 in a dose-dependent manner. Moreover, [126I]-bFGF binding experiments indicated the existence of both high and low affinity binding sites on myoblast membranes, although the high affinity binding sites decreased in number and the dissociation constant increased in value as the culture period was prolonged. Among the six other growth factors examined, acidic fibroblast growth factor and platelet-derived growth factor-BB stimulated myogenesis, and their effects were blocked by PF4 treatment. These findings suggest that: 1) PF4 inhibits myoblast proliferation and myotube formation only for a limited initial period of cultivation, possibly because of the time-dependent down-regulation of high affinity bFGF receptors: and 2) PF4 may be used as a tool to investigate the function of endogenous heparin-binding growth factors upregulated transiently at a certain developmental stage or in case of tissue damage and repair, even though it is not monospecific to bFGF.

Animals↗

PubMed1997

Vomiting induction by ipecac syrup in dogs and ferrets.

The dog has been used as an experimental animal in emesis research. In this study, we analyzed the emetic effects of ipecac syrup using a smaller animal, the ferret, and compared its response to that of the dog. Dogs and ferrets were divided into 4 groups (n = 4, each). Each group was given either 0.1, 0.25, 0.5, or 1.0 ml/kg of ipecac syrup, and the latency and numbers of retching and vomiting were recorded. Animals given an equal volume of saline served as controls. The numbers of vomiting and retching increased dose-dependently in both dogs and ferrets, and there was no difference in latency and numbers of vomiting between them. The numbers of retching were greater in ferrets than in dogs at > or = 0.25 ml/kg. Taking these results into consideration, the ferret seems to be as useful as the dog in studies on emetic effects of ipecac syrup.

Animals↗

PubMed1997

Myelinated nerve fibre analysis of the human small splanchnic nerve.

The aim of the present study is to analyse nerve fibres of the human small splanchnic nerve in relation to the ageing process. The analysis was conducted with the use of a new staining method that makes it possible to discriminate various structures of the nervous tissue. An image-analysing digitiser, a microscope with a drawing tube and a personal computer for storing data and performing statistical analyses were employed in this study. We examined 30 human small splanchnic nerves which were taken from cadaver specimens (20 males and 10 females) aged from 44 to 96 years. Our report may provide a first information concerning the ageing process of the human small splanchnic nerve. The results indicate that a decrease in transverse area and perimeter of myelinated axons in one of the important changes occurring in the human small splanchnic nerve with the ageing process.

Adult↗

PubMed1997

Clinical relevance of serum soluble interleukin-2 receptor levels in acute and chronic graft-versus-host disease.

Soluble interleukin-2 receptor (sIL-2R) levels were analyzed in the sera from 27 patients who underwent allogeneic bone marrow transplantation (BMT) in order to to examine whether there was any correlation between sIL-2R levels and graft-versus-host disease (GVHD). The sIL-2R levels markedly increased at the engraftment period, mainly due to cytokine administration shortly after BMT. Although the sIL-2R levels increased at the onset of acute GVHD, the subsequent development of GVHD could not be predicted by the sIL-2R levels documented before acute GVHD. As acute GVHD improved, the sIL-2R levels decreased, thus showing that the sIL-2R levels correlated with the disease status. In patients without acute GVHD, the sIL-2R levels gradually decreased with time and returned to the pretransplant levels after about 12 weeks post BMT. The sIL-2R levels were higher in unrelated allogeneic BMT patients with acute GVHD when compared with related allogeneic BMT patients. There was a significant increase in the sIL-2R levels at the engraftment period and at the onset of acute GVHD. At the onset of chronic GVHD, the sIL-2R levels once again increased and then decreased as chronic GVHD improved. Prolonged increase in sIL-2R levels was followed by subsequent development of chronic GVHD. Patients with a poor prognosis had higher sIL-2R levels than those with a good prognosis. Therefore, it seems that sIL-2R is a useful marker for monitoring the disease status of acute and chronic GVHD.

Adolescent↗

PubMed1997

A translocation t(8;14) and c-myc gene rearrangement associated with the histological transformation of B-cell acute lymphocytic leukemia (FAB-L2) into Burkitt's type (FAB-L3) leukemia.

We report a case of B-cell acute lymphocytic leukemia which showed histological transformation from an FAB-L2 into a Burkitt's type (FAB-L3). Both leukemias had identical immunoglobulin heavy-chain joining gene and kappa light-chain joining gene rearrangements, indicating the clonal identity of the two leukemias. A chromosomal analysis of leukemia cells on the onset indicated normal karyotype, whereas that of the transformed FAB-L3 showed t(8;14)(q24;q32). Furthermore, the proto-oncogene c-myc was in the germline configuration in the initial leukemia but in the rearranged configuration after transformation. Presence of t(8;14)(q24;q32) and the c-myc gene rearrangement after transformation suggested that the chromosomal translocation followed by the activation of the c-myc proto-oncogene might be involved in the Burkitt's type transformation of the FAB-L2 leukemic clone, but not in the leukemogenesis of the initial FAB-L2 leukemia.

Adolescent↗

PubMed1997

Low levels of serum soluble c-kit relates to delayed engraftment after bone marrow transplantation.

Serum soluble c-kit concentrations were measured in 28 patients undergoing bone marrow transplantation (BMT). The c-kit levels in patients with delayed engraftment (time to leukocyte recovery > 1.0 x 10(9)/L being more than 20 days after BMT) were significantly lower than those in patients with early engraftment (time to leukocyte recovery being less than 19 days after BMT) from the start of conditioning until day 100 after BMT. The data from this study indicates that the measurement of serum soluble c-kit concentrations may be a useful indicator of engraftment.

Adolescent↗