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Biomedical subjects

K Kaneko

Publications and source records attributed to K Kaneko.

At least 289 records · Page 16Linked to original sources
PubMed1998

[Implementing HPN in an SEP case following long-term CAPD].

BACKGROUND: Sclerosing encapsulating peritonitis (SEP) is one of the most serious complications in continuous ambulatory peritoneal dialysis (CAPD). SEP causes severe bowel obstruction leading to malnutrition and eventually to a high mortality rate. The basic strategy for the care of SEP is to sustain the rest of the bowel, i.e., long-term TPN. We report a case successfully restored to a useful life through HPN. CASE PRESENTATION: The patient is a 26-year-old man, diagnosed as primary nephrotic syndrome in 1980. He had to begin hemodialysis (HD), which was immediately switched to CAPD, due to uremia in 1983. He had been on CAPD for 12 years since that time. He developed SEP as a serious complication of CAPD in July, 1995. CAPD was discontinued, and maintenance HD was started three times a week. Although only liquid diet (such as Renalen and Ensure-Liquid) was allowed as a meal, he often developed intermittent bowel obstruction and repeated hospitalizations were needed to relieve the symptoms. Home parenteral nutrition (HPN) was implemented in May, 1997, in the hope of improving his quality of life. No hospitalization has been needed since then. At present, he is working as an active pharmacist utilizing the HPN system developed by Terumo Co., Ltd. So far a few HPN pump failures have been encountered, but they were promptly handled by the Home Health Care Business Project staff at Terumo Co., Ltd. CONCLUSION: Although further improvements of the present HPN system are necessary, HPN can be a useful tool to effectively manage SEP patients who are suffering from persistent or intermittent bowel obstruction.

Adult↗
PubMed1997

Spatial distribution of corticospinal potentials following transcranial electric and magnetic stimulation in human spinal cord.

To investigate the spatial distribution of the human corticospinal tract in the spinal cord, evoked spinal cord potentials (ESCPs) following transcranial electrical and magnetic stimulation were recorded simultaneously from both the anterior and posterior epidural space in five anesthetized patients. One ESCP component following transcranial electrical stimulation (D-wave) and at least two ESCP components (initially D-wave and later I-wave) following transcranial magnetic stimulation were recorded in all subjects. The negative peak latency of all the potentials recorded from the posterior epidural space was the same as that recorded anteriorly. The amplitude ratio of the ESCP following electrical stimulation (posterior/anterior) was 1.10+/-0.12, while that of ESCPs following magnetic stimulation was 1.08+/-0.12 (N1) and 1.15+/-0.16 (N2). These results suggest that lateral corticospinal tract descending dorsolateral fasciculus in the spinal cord is main corticospinal pathway and spatial distribution of D and I-waves are similar in the human cervical cord.

Cerebral Cortex↗
PubMed1997

Identification and characterization of an anti-glial fibrillary acidic protein antibody with a unique specificity in a demented patient with an autoimmune disorder.

We detected an antibody to a 48 kd antigen of the central nervous system in the serum from a demented patient with an autoimmune disorder. To identify and characterize the antigen, we screened a human cerebral cDNA library and performed immunoblot analysis following two-dimensional gel electrophoresis (2-D blotting). The sequences of the isolated cDNA fragments were homologous to human glial fibrillary acidic protein (GFAP). Two-D blotting using patient serum revealed that the antibody reacted with a restricted subset of GFAP molecules which exhibited relatively high isoelectric points. Furthermore, to elucidate the importance of the anti-GFAP antibody in dementia, we screened for the presence of an anti-GFAP antibody in the sera of 46 demented patients: 26 with Alzheimer's disease and 20 with vascular dementia (VD). We found an anti-GFAP antibody in the serum of only one patient with VD. Two-D blotting revealed that the anti-GFAP antibody in the serum from the VD patient reacted with a more acidic subset of GFAP molecules compared with the anti-GFAP antibody from our patient. In conjunction with the fact that the GFAP molecule with high isoelectric point was insoluble and less degraded, these results suggested that the anti-GFAP antibody in the serum of our patient was not generated due to a secondary response to soluble and degraded GFAP which leaked through the damaged blood-brain barrier as found in the VD patient, but was generated actively on the basis of dysregulation of the immune system. Possible effects of the autoantibody on astrocytic function and the pathogenesis in dementia are discussed.

Alzheimer Disease↗
PubMed1997

Evidence for protein X binding to a discontinuous epitope on the cellular prion protein during scrapie prion propagation.

Studies on the transmission of human (Hu) prions to transgenic (Tg) mice suggested that another molecule provisionally designated protein X participates in the formation of nascent scrapie isoform of prion protein (PrPSc). We report the identification of the site at which protein X binds to the cellular isoform of PrP (PrPC) using scrapie-infected mouse (Mo) neuroblastoma cells transfected with chimeric Hu/MoPrP genes even though protein X has not yet been isolated. Substitution of a Hu residue at position 214 or 218 prevented PrPSc formation. The side chains of these residues protrude from the same surface of the C-terminal alpha-helix and form a discontinuous epitope with residues 167 and 171 in an adjacent loop. Substitution of a basic residue at positions 167, 171, or 218 also prevented PrPSc formation: at a mechanistic level, these mutant PrPs appear to act as "dominant negatives" by binding protein X and rendering it unavailable for prion propagation. Our findings seem to explain the protective effects of basic polymorphic residues in PrP of humans and sheep and suggest therapeutic and prophylactic approaches to prion diseases.

Animals↗
PubMed1997

Solution structure of a 142-residue recombinant prion protein corresponding to the infectious fragment of the scrapie isoform.

The scrapie prion protein (PrPSc) is the major, and possibly the only, component of the infectious prion; it is generated from the cellular isoform (PrPC) by a conformational change. N-terminal truncation of PrPSc by limited proteolysis produces a protein of approximately 142 residues designated PrP 27-30, which retains infectivity. A recombinant protein (rPrP) corresponding to Syrian hamster PrP 27-30 was expressed in Escherichia coli and purified. After refolding rPrP into an alpha-helical form resembling PrPC, the structure was solved by multidimensional heteronuclear NMR, revealing many structural features of rPrP that were not found in two shorter PrP fragments studied previously. Extensive side-chain interactions for residues 113-125 characterize a hydrophobic cluster, which packs against an irregular beta-sheet, whereas residues 90-112 exhibit little defined structure. Although identifiable secondary structure is largely lacking in the N terminus of rPrP, paradoxically this N terminus increases the amount of secondary structure in the remainder of rPrP. The surface of a long helix (residues 200-227) and a structured loop (residues 165-171) form a discontinuous epitope for binding of a protein that facilitates PrPSc formation. Polymorphic residues within this epitope seem to modulate susceptibility of sheep and humans to prion disease. Conformational heterogeneity of rPrP at the N terminus may be key to the transformation of PrPC into PrPSc, whereas the discontinuous epitope near the C terminus controls this transition.

Amino Acid Sequence↗
PubMed1997

Molecular properties of complexes formed between the prion protein and synthetic peptides.

Complexes of the Syrian hamster cellular prion protein (PrPC) and synthetic Syrian hamster PrP peptides were found to mimic many of the characteristics of the scrapie PrP isoform (PrPSc). Either PrPC expressed in chinese hamster ovary (CHO) cells or a C-terminal fragment of 142 residues of recombinant PrP protein (rPrP) produced in Escherichia coli was mixed with an excess of a synthetic 56 amino acid peptide, denoted PrP(90-145). Complex formation required PrPC or rPrP to be destabilized by guanidine hydrochloride (GdnHCl) or urea and PrP(90-145) to be in a coil conformation; it was enhanced by an acidic environment, salt and detergent. If PrP(90-145) was in a beta-sheet conformation, then no complexes were formed. While complex formation was rapid, acquisition of protease resistance was a slow process. Amorphous aggregates with a PrPC/PrP(90-145) ratio of 1:1 were formed in phosphate buffer, whereas fibrils with a diameter of approximately 10 nm and a PrPC/PrP(90-145) ratio of 1:5 were formed in Tris buffer. The complexes were stable only in the presence of excess peptide in either the coil or beta-sheet conformation; they dissociated rapidly after centrifugation and resuspension in buffer without peptide. Neither a peptide having a similar hydrophobicity profile/charge distribution to PrP(90-145) nor a scrambled version, denoted hPrP(90-145) and sPrP(90-145), respectively, were able to induce complex formation. Although hPrP(90-145) could stabilize the PrPC/PrP(90-145) complexes, sPrP(90-145) could not. Studies of PrPC/peptide complexes may provide insights into how PrPC interacts with PrPSc during the formation of a nascent PrPSc molecule and into the process by which PrPC is converted into PrPSc.

Amino Acid Sequence↗
PubMed1997

Effect of coil position and stimulus intensity in transcranial magnetic stimulation on human brain.

Evoked spinal cord potentials (ESCPs) from the cervical and high thoracic epidural space following transcranial magnetic stimulation were recorded from eight subjects in awake and anesthetized condition. Motor evoked potentials (MEPs) from the right abductor digiti minimi (ADM) and rectus femoris (RF) muscles were simultaneously recorded during voluntary contraction. The stimulus intensity was at 30% above the MEPs threshold of the ADM when the coil center was fixed on 10-20 international Cz position. In awake condition, multiple ESCP components (greater than 3) were recorded from the cervical epidural space but no or minimal components were recorded from the upper thoracic epidural space. When the coil was moved anteriorly so that the posterior edge of the coil was positioned on Cz, the amplitude of the first ESCP component was significantly increased (P < 0.02) and shortened (not significant) at cervical levels. In addition, several ESCP components were more evident at high thoracic levels. Although the amplitude of the ADM was not enhanced, that of the RF was enhanced. During general anesthesia with volatile anesthetics (sevoflurane), only the first component of the ESCPs (D-wave) was elicited. Its amplitude was enhanced (P < 0.02) when the coil edge was fixed on Cz, similar to results in awake condition. This enhancement of the first ESCP component was accompanied by enhancement of those recorded from the high thoracic epidural space. However the amplitude of D-wave was the same in the two different coil positions when the stimulus intensity was set a 100% of the output. These results suggest that at low stimulus intensity, positioning the coil edge on Cz is optimal in inducing D-wave effectively but at high stimulus intensity, D-wave generation can be achieved in either if the two different coil position.

Adult↗
PubMed1997

Developmental acquisition of enhancer function requires a unique coactivator activity.

Enhancers are believed to stimulate promoters by relieving chromatin-mediated repression. However, injection of plasmid-encoded genes into mouse oocytes and embryos revealed that enhancers failed to stimulate promoters prior to formation of a two-cell embryo, even though the promoter was repressed in the maternal nucleus of both oocytes and one-cell embryos. The absence of enhancer function was not due to the absence of a required sequence-specific enhancer activation protein, because enhancer function was not elicited even when these proteins either were provided by an expression vector (GAL4:VP16) or were present as an endogenous transcription factor (TEF-1) and shown to be active in stimulating promoters. Instead, enhancer function in vivo required a unique coactivator activity in addition to enhancer-specific DNA binding proteins and promoter repression. This coactivator activity first appeared during mouse development in two- to four-cell embryos, concurrent with the major onset of zygotic gene expression. Competition between various enhancers was observed in these embryos, but not competition between enhancers and promoters, and competition between enhancers was absent in one-cell embryos. Moreover, enhancer function in oocytes could be partially restored by pre-injecting mRNA from cells in which enhancers were active, the same mRNA did not affect enhancer function in two- to four-cell embryos.

Animals↗
PubMed1997

COOH-terminal sequence of the cellular prion protein directs subcellular trafficking and controls conversion into the scrapie isoform.

Efficient formation of scrapie isoform of prion protein (PrP(Sc)) requires targeting PrP(Sc) by glycophosphatidyl inositol (GPI) anchors to caveolae-like domains (CLDs). Redirecting the cellular isoform of prion protein (PrP(C)) to clathrin-coated pits by creating chimeric PrP molecules with four different COOH-terminal transmembrane domains prevented the formation of PrP(Sc). To determine if these COOH-terminal transmembrane segments prevented PrP(C) from refolding into PrP(Sc) by altering the structure of the polypeptide, we fused the 28-aa COOH termini from the Qa protein. Two COOH-terminal Qa segments differing by a single residue direct the transmembrane protein to clathrin-coated pits or the GPI form to CLDs; PrP(Sc) was formed from GPI-anchored PrP(C) but not from transmembrane PrP(C). Our findings argue that PrP(Sc) formation is restricted to a specific subcellular compartment and as such, it is likely to involve auxiliary macromolecules found within CLDs.

Animals↗
PubMed1997

Coexisting peripheral nerve and cervical cord compression.

STUDY DESIGN: The authors investigated the clinical usefulness of recording motor evoked potentials after transcranial magnetic stimulation in coexisting peripheral nerve and cervical cord lesions. OBJECTIVE: To show that the measurement of central motor conduction time from the abductor policis brevis and the abductor digiti minimi can be used as a good screening method for double lesions involving peripheral nerves and the cervical cord. SUMMARY OF BACKGROUND DATA: Transcranial magnetic stimulation has been used in the diagnosis of compressive cervical myelopathy. This technique could be useful in the assessment of patients with an entrapment neuropathy and cervical myelopathy. METHODS: Motor evoked potentials after transcranial magnetic stimulation, compound muscle action potentials, and F waves after supramaximal peripheral nerve stimulation were recorded from the abductor policis brevis and the abductor digiti minimi. The central motor conduction time was calculated by subtracting the peripheral conduction time from the motor evoked potentials latency. RESULTS: Ten patients with coexisting peripheral nerve and cervical cord lesions were evaluated. Two patients did not show satisfactory improvement after the decompression of the entrapment lesions, and six patients had hyperreflexia of lower limbs. In seven of these patients, the central motor conduction time was prolonged an average of 2.5 standard deviation of the normal value. The remaining two patients had spinal cord compression due to the ossification of the posterior longitudinal ligament. The spinal cord compression was demonstrated by magnetic resonance imaging, but the central motor conduction time was normal. Subjective symptoms improved in these two patients after decompressive surgery at the entrapment site alone. CONCLUSIONS: Measurement of the central motor conduction time using motor evoked potentials is an ideal diagnostic approach for patients with coexisting entrapment neuropathy and cervical cord compression.

Carpal Tunnel Syndrome↗
PubMed1997

Isologous diversification: a theory of cell differentiation.

An isologous diversification theory for cell differentiation is processed, based on simulations of interacting cells with biochemical networks and the cell division process following consumption of some chemicals. According to the simulations of the interaction-based dynamical systems model, the following scenario of the cell differentiation is proposed. (1) Up to some threshold number, divisions bring about almost identical cells with synchronized biochemical oscillations. (2) As the number is increased, the oscillations lose synchrony, leading to groups of cells with different phases of oscillations. (3) Amplitudes of oscillation and averaged chemical compositions start to differ by groups of cells. The differentiated behavior of states is transmitted to daughter cells. (4) Recursivity is formed so that the daughter cells keep the identical chemical character. This "memory" is made possible through the transfer of initial conditions. (5) Successive differentiation proceeds. The mechanism of tumor cell formation, origin of stem cells, anomalous differentiation by transplantations, apoptosis and other features of cell differentiation process are also discussed, with some novel predictions.

Animals↗
PubMed1997

Operative treatment of congenital stenoses of the intrahepatic bile ducts in patients with choledochal cysts.

BACKGROUND: Postoperative complications including intrahepatic calculi may develop after the complete excision of a choledochal cyst. Since congenital stenoses of the intrahepatic bile ducts are more likely the cause of intrahepatic calculi, operative procedures for intrahepatic stenoses are reported. METHODS: There were 16 patients with choledochal cysts who underwent surgery for stenoses of intrahepatic bile ducts. The stenoses were excised at the opening of the common hepatic duct. RESULTS: In the 16 patients, 25 of the 26 stenoses that involved an intraluminal membrane or septum could be excised from the divided end of the common hepatic duct at the hepatic hilum. In 1 patient, the stenosis could not be accessed from the hepatic hilum, and a left hepatic lobectomy was required. In postoperative follow-up, all 16 patients were in good health. CONCLUSIONS: Stenoses of the intrahepatic bile ducts should be treated from the divided end of the common hepatic duct at the initial operation for choledochal cysts. The need for a second operation or hepatic lobectomy may thus be avoided.

Adolescent↗
PubMed1997

A new hepatic portoenterostomy with division of the ligamentum venosum for treatment of biliary atresia: a preliminary report.

BACKGROUND/PURPOSE: Kasai's operation consists of transection of the fibrous portal cord including the bile duct remnant. However, it is difficult to transect the fibrous cord at the level of the posterior surface of the portal vein, because the portal vein is fixed at the porta hepatis. METHODS: The authors described a new hepatic portoenterostomy to transect the fibrous cord under an appropriate visual field by division of the ligamentum venosum (Arantius' canal). Between February and December 1996, six patients who had biliary atresia underwent this procedure. RESULTS: Jaundice resolved completely (TB < or = 1.0 mg/dL) in all six patients within 40 days. Postoperative cholangitis did not occur and good bile drainage was obtained. CONCLUSIONS: Using this procedure, the portal vein becomes fully mobile after dividing the ligamentum venosum, and the porta hepatis can be widely exposed. The fibrous cord of the porta hepatis can be easily dissected off posteriorly and laterally.

Biliary Atresia↗
PubMed1997

Effect of retained placenta on subsequent bacteriological and cytological intrauterine environment and reproduction in Holstein dairy cows.

To determine the effect of retained placenta on the characteristics of the intrauterine environment in dairy cows, bacteriological and cytological tests were performed on intrauterine perfusion fluid. The rate of cows with more than 70% neutrophils or fewer than 40% lymphocytes in inflammatory cells was 48.0% (12/25), while the rate and with more than 50 bacterial colonies/0.1 ml of perfusate was 96.0% (24/25) at 30 d after parturition. Actinomyces pyogenes was isolated from 56.0% (14/25). At 60 d after parturition, however, these values were significantly improved to 20.0% (5/25), 48.0% (12/25) and 12.0% (3/25), respectively. No significant differences in subsequent reproductive performance were observed between cows with and without retained placenta. The results suggest that injury to the intrauterine environment caused by retained placenta is largely healed by 60 d after parturition.

Journal Article↗
PubMed1997

Neuropathic pain and prolonged regional inflammation as two distinct symptomatological components in complex regional pain syndrome with patchy osteoporosis--a pilot study.

To reappraise symptomatology of complex regional pain syndrome (CRPS), we investigated the clinical symptoms of seven patients with CRPS who showed associated patchy osteoporosis. The incidence of moderate to severe spontaneous pain, burning pain, mechanical allodynia was higher in patients with significant nerve injury than in those without. Periarticular tenderness adjacent to osteoporotic bones, abnormalities of blood flow, edema and impairment of motor function were seen in both groups of patients. Our clinical observations of patients with CRPS associated with patchy osteoporosis suggest that CRPS may have the following two distinct components: (1) neuropathic pain that includes severe spontaneous pain or severe persistent mechanical allodynia and (2) prolonged regional inflammation, the early phase of which could be indicated by positive inflammatory symptoms of pain (tenderness), heat, redness, swelling and loss of function and their alleviation with corticosteroids.

Adult↗
PubMed1997

Morphology of capillary-like structures in a three-dimensional aorta/collagen gel culture.

The morphology of capillary-like tubes was investigated by electron microscopy (TEM and SEM) using an in vitro model of capillarogenesis (aorta/collagen type I gel). This model allowed morphological comparisons with in vivo capillaries and an evaluation of the functional maturity of the endothelium to be made. The lumina developing in vitro were demarcated by endothelial cells of varying thickness (0.1-2 microns). Pericytes were resting on the outside. The endothelial cells were characterized by contacts of varying length with tight and gap junctions and occasional indentations. The inner surface exhibited areas both with pronounced and without any endocytotic activity. In addition to a large Golgi apparatus, a varying number of cell organelles occurred depending on the thickness of the endothelium. Bundles consisting of microfilaments were often located underneath the outer cell membrane and in the vicinity of contact areas. A lamina densa was in the process of formation. The capillaries grown in vitro closely resembled those in vivo and showed a high degree of differentiation. Hence, this in vitro model allows the study of a number of functions of endothelial cells.

Animals↗