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Biomedical subjects

N Kojima

Publications and source records attributed to N Kojima.

At least 181 records · Page 10Linked to original sources
PubMed1989

Purification to homogeneity of human placental acid sphingomyelinase.

Acid sphingomyelinase was purified to homogeneity from human placenta in the presence of a dialyzable detergent, n-octyl-beta-D-glucopyranoside. The major steps in the procedure included column chromatographies with Con A-Sepharose, sphingosylphosphorylcholine-Sepharose 4B, hexyl-agarose, and Mono P. The purified enzyme with pI 7.4 had a specific activity of approx 170,000 units/mg protein with a yield of 3.6%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single protein band of Mr 62,000. Gel filtration with a Superose 12 column gave a single peak, and the enzyme in the presence 50 mM n-octyl-beta-D-glucopyranoside was of Mr 123,000, indicating that the native enzyme occurs in a dimeric form. The optimal pH was 5.5 with both sphingomyelin and an artificial substrate, 2-N-hexadecanoylamino-4-nitrophenylphosphorylcholine. The Km values were 55 microM with sphingomyelin and 340 microM with the artificial substrate. The enzyme activity was not affected by Mg2+ (1-5 mM), confirming that the enzyme is acid sphingomyelinase. The enzyme was stable at -80 degrees C for more than 4 months. In addition to the enzyme with pI 7.4, the Mono P chromatofocusing gave two peaks (pI 7.0 and 6.7) possessing the enzymatic activity.

Chromatography, Gel↗
PubMed1988

Pyruvic-acid-containing polysaccharide in the cell wall of Bacillus polymyxa AHU 1385.

Three acidic polymer fractions with molecular masses of about 16 kDa, 35 kDa and 70 kDa were isolated from lysozyme digests of N-acetylated cell walls of Bacillus polymyxa AHU 1385 by ion-exchange chromatography and gel chromatography. These fractions, containing mannosamine, glucosamine and pyruvic acid in a molar ratio of about 1:1:1 together with glycopeptide components, were characterized as polysaccharide-linked glycopeptides with one, two and more polysaccharide chains. On the other hand, treatment of the cell walls with glycine/HC1 buffer, pH 2.5, at 100 degrees C for 10 min followed by separation of water-soluble products on ion-exchange chromatography gave three polysaccharide fractions, PS-I-III, which contained different amounts of pyruvic acid (0,0.6 and 0.9 residue/mannosamine residue) along with equimolar amounts of mannosamine and glucosamine. Pyruvate-free polysaccharides similar to PS-I were also obtained from PS-II, PS-III and polysaccharide-linked glycopeptides by treatment with 10 mM HC1 at 100 degrees C for 1 h. Results of analyses of these polysaccharide preparations by 1H-NMR and 13C-NMR measurement and methylation, together with data from characterization of fragments obtained by hydrogen fluoride hydrolysis, lead to the most likely structure, ----3)[4,6-O-(1-carboxyethylidene)]ManNAc(beta 1----4)GlcNac(beta 1----, for the acidic polysaccharide of this strain.

Acetylglucosamine↗
PubMed1988

Molecular cloning of a cDNA for the developmentally regulated brain protein, drebrin.

A lambda gt11 cDNA library from 10-day-old chicken embryo was screened immunologically using an antiserum against drebrins E1, E2 and A, proteins previously designated S5, S6 and S54, respectively. A cDNA clone for a common domain of drebrin was isolated. Northern blot analysis of chicken brain indicated that drebrin mRNAs are about 2.7 kilobases in molecular size and that expression of these proteins is developmentally regulated.

Animals↗
PubMed1988

Nucleotide sequences of two embryonic drebrins, developmentally regulated brain proteins, and developmental change in their mRNAs.

Drebrins are developmentally regulated proteins found in chicken brain and are classified into two forms of the embryonic type (E1 and E2) and one form of the adult type (A). Although the time courses of their appearance are different from each other, the structures of the 3 forms are closely related. Two kinds of drebrin cDNA, designated gDcw6 and gDcw17, were isolated from the cDNA library of the chicken embryo and their nucleotide sequences were determined. Their sequences were entirely identical except for a deletion of an internal 129-nucleotide sequence, and the gDcw17 insert contained an open reading frame capable of encoding 607 amino acids. These cDNAs seemed to correspond to two embryonic forms of drebrin mRNAs. The predicted drebrin molecules are highly hydrophilic and have proline-rich sequences and long stretches of glutamate in the carboxyl-terminal region. RNA dot-blot analysis using the drebrin cDNA as a probe demonstrated that the amounts of drebrin mRNAs were also developmentally regulated as those of drebrins. Southern blot analysis showed that the chicken genome has a single copy of the drebrin gene per haploid complement. These findings suggest that the multiple forms of drebrins result from alternative splicing of the single drebrin gene during neural development.

Amino Acid Sequence↗
PubMed1988

Tethered cord syndrome of delayed onset following repair of myelomeningocele.

Nine (15%) of 60 patients with repaired myelomeningocele exhibited late deterioration of neurological function with a tethered cord syndrome. Dense adhesions at the lowest laminae and at the site of previous repair were the most common findings at surgery. Postoperatively, 71% of the patients improved. Magnetic resonance (MR) imaging was performed in 29 of the 60 patients. Eight of these 29 patients exhibited a tethered cord syndrome. The MR images in all patients showed a low-lying conus fixed at the site of previous repair, irrespective of the presence or absence of a tethered cord syndrome. The MR images were classified into two groups depending upon the site of adhesions: Group A had potential sites of tethering at the ventral aspect of the last laminae and at the site of previous repair, and Group B showed the adhesion point only at the site of previous repair. Most patients with a tethered cord syndrome were found to be in Group A; conversely, most patients without the syndrome were in Group B. An enlarged low conus was seen in symptomatic patients more commonly than in those without this syndrome. It is concluded that the presence of adhesions specifically at the last laminae as well as a widened low-lying conus may be the cause of tethered cord syndrome in patients with repaired myelomeningoceles. A clear understanding of the tethering process and preoperative evaluation of potential sites of tethering, based on the MR findings, are very important for planning surgery. The release of adhesions at the lowest laminae by laminectomy appeared essential for improvement.

Adolescent↗
PubMed1988

Mode of binding of adriamycin with sulfatide-containing liposomes.

Association constants and maximum binding numbers of sulfatide- and phosphatidylserine (PS)-containing liposomes for their binding with adriamycin (ADM) were determined by the column equilibration method. Although these liposomes have two kinds of binding sites, hydrophobic and electrostatic, the majority of ADM molecules was associated with the liposomes via their latter binding sites. Since the association constant for the electrostatic binding of ADM was smaller in sulfatide-containing liposomes (3 x 10(3) M-1) than in PS-containing ones (1.1 x 10(4) M-1), high efficiency of sulfatide-containing liposomes for the entrapment of ADM might be explained by the effect of sulfatide making the liposomes rigid, thereby preventing the leakage of the entrapped ADM.

Binding Sites↗
PubMed1988

[Evaluation of shunt treatment in hydrocephalus with myelomeningocele: some factors relating to mental prognosis].

From 1971 to 1986, the authors experienced 64 patients of myelomeningocele. Sixty out of 64 cases (94%) had both myelomeningocele and hydrocephalus. A retrospective analysis about these hydrocephalic patients was conducted on various factors relating to intelligence. Forty-nine cases received cerebrospinal fluid diversion operation within 2 years of life, while 6 cases had ventriculo-peritoneal shunt after 7 years of age and 5 cases had no surgical treatment for hydrocephalus. Statistically the following factors were significantly related to low intelligence: 1) ventriculitis suffered within two months of life: 2) association of symptomatic Arnold-Chiari malformation, and 3) myelodysplasia at or above the L2 level. However, there was no statistically significant relationship between mental prognosis and age at initial shunt, degree of ventricular dilatation before and after shunt, numbers of shunt revision, epilepsy, or subdural hematoma after shunt. These findings suggest that hydrocephalic patients with myelomeningocele will be expected to have better mental prognosis if the hydrocephalus is well controlled by shunting and if they do not have other severe malformations of the central nervous system.

Abnormalities, Multiple↗
PubMed1988

[Clinical evaluation of an isolated fourth ventricle].

Since the introduction of the CT scan in 1976, we have experienced 6 cases of the isolated fourth ventricle among 244 hydrocephalic patients (2.5%). Age at diagnosis of the isolated fourth ventricle ranged from 1 year 8 months to 13 years (mean age, 8 years, 6 months). The time interval between the first shunting procedure and the diagnosis of the isolated fourth ventricle varied from 1 year 5 months to 7 years 4 months (mean interval, 4 years 1 months). The prior hydrocephalus were due to intraventricular hemorrhage in two patients, meningomyelocele in a patient and brain tumor in three patients. Two patients had history of cerebrospinal fluid (CSF) infection and five cases underwent multiple shunt revisions. Posterior fossa signs were evident in all cases. It was quite easy to make a diagnosis of the isolated fourth ventricle with CT scan, which demonstrated a large rounded or pear-shaped midline cyst in the posterior fossa. Slit-like lateral ventricles were noted in three cases, while the remaining three had enlarged lateral ventricles. Ventriculography confirmed the isolation of the fourth ventricle in 5 cases. Metrizamide which had been injected into the fourth ventricle was diluted when CT scan was performed 48 hours later, and contrast medium disappeared since then. Magnetic resonance imaging (MRI) well showed the characteristic findings of the isolated fourth ventricle: cystic dilatation of the fourth ventricle, compression and distortion of the brain stem, upward tentorial herniation, occlusion of the aqueduct, downward displacement of the occipital lobe, septum formation of the fourth ventricle and accompanied anomalies such as, Chiari malformation or syringomyelia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Preparation of an immunoadsorbent interacting specifically with cortisol-binding globulin (CBG) and its application to the interaction between CBG and cortisol--evaluation of the association constant (Ka) between CBG and cortisol in normal subjects].

We have developed a simple method for the evaluation of the association constant (Ka) between cortisol binding globulin (CBG) and cortisol using immunoadsorbent and a small amount of serum. Immunoadsorbent was prepared as follows; gamma-globulin fraction was obtained from goat anti-human CBG antiserum by salting out using 50% ammonium sulfate, followed by coupling to CNBr-activated Sepharose 4B. Immunoadsorbent thus prepared was used for the evaluation of Ka value between cortisol and CBG. Sera obtained from 5 healthy subjects (3 males and 2 females) were treated with charcoal (Norit A) to remove endogenous cortisol. Each of 10 microliter of serum was incubated with a constant amount of 125I-cortisol and different concentrations of unlabelled cortisol for 12 hours at 25 degrees C, pH 7.4. Then, 50 microliter of anti-CBG-Sepharose 4B (immunoadsorbent) was added to each incubation mixture, followed by incubation for another 4 hours at 25 degrees C. After centrifugation, radioactivity of the precipitate was counted and the results were analyzed using Scatchard plot. The Ka value between serum CBG and cortisol in 5 healthy subjects was 1.70 X 10(8)M-1 (SD = 0.24), which is comparable with that of a previously reported value using purified CBG from a large amount of serum. Interassay variation of this method was satisfactory with CV value of 10.1%. Our present method is considered to be clinically relevant, since it does not require purification of CBG from serum, and a relatively small amount (total amount, less than 200 microliter) of serum is enough to evaluate Ka value between CBG and cortisol.

Adult↗
PubMed1987

Four synaptic vesicle-specific proteins: identification by monoclonal antibodies and distribution in the nervous tissue and the adrenal medulla.

Synaptic vesicles from the guinea-pig cerebrum were isolated and administered to mice for the production of monoclonal antibodies (MAb). Four vesicle-associated proteins in the guinea-pig nervous tissue were specifically and differentially recognized by MAbs thus obtained. These proteins had molecular weights of 30,000, 36,000, 38,000 and 65,000 Da and were named SVPs (synaptic vesicle proteins) 30, 36, 38 and 65, respectively. Immunohistochemistry demonstrated that all SVPs were localized in the synaptic regions throughout the central nervous system and in the adrenal medulla. Nerve terminals in skeletal muscle, smooth muscle and sympathetic ganglion contained SVPs 36 and 38. Immunoelectron microscopy of the cerebellar cortex confirmed the localization of SVPs in the synaptic vesicles and the adjacent membranes of the presynaptic nerve terminals. Fractionation of the cerebral tissue and treatment with various agents showed that SVPs were localized in the synaptic vesicles and the synaptic plasma membrane and that SVPs were integrated within the membrane and liberated only after solubilization of the membrane.

Adrenal Medulla↗
PubMed1987

Molecular events associated with neural development.

Analyses of the chick embryo using two-dimensional gel electrophoresis or immunohistochemistry with monoclonal antibodies (MAbs) revealed several molecules which were highly concentrated in the nervous tissue. The properties and developmental changes of these substances were investigated. Three acidic proteins (molecular weights 95, 100 and 110 kDa, respectively) appeared characteristically during the embryonic development. One of them predominated alternatively at each developmental stage. They showed a high degree of homology in the peptide map and complete cross-reactivity with any specific antibodies. Therefore these proteins were considered to make a protein family and were collectively named drebrins. MAbs were produced against the membrane fraction of the neural tubes and somites of three-day chick embryos. Five MAbs stained the migrating neural crest cells and their progeny in histochemistry. In addition, the otic vesicle, including the differentiated labyrinth, and subtypes of human lymphocytes were recognized by these MAbs.

Animals↗
PubMed1987

Possible neurotransmitters of the dorsal column afferents: effects of dorsal column transection in the cat.

We investigated quantitative changes in markers of possible neurotransmitters in the dorsal column nuclei following transection of the dorsal column in the cat. Seven days after unilateral transection of the dorsal column at the upper cervical level, choline acetyltransferase activity and concentrations of glutamate, aspartate, gamma-aminobutyrate and substance P were measured throughout the longitudinal axis of the dorsal column nuclei. In addition, high-affinity uptake of choline, D-aspartate and gamma-aminobutyrate into the synaptosomal fraction of the dorsal column nuclei were also measured. Choline acetyltransferase activity and high-affinity choline uptake were reduced by approx. 30% on the caudal to the obex. Reduction of high-affinity uptake of D-aspartate by approx. 30% was observed on the operated side in the central part of these nuclei, although the decrease in glutamate and aspartate was not significant in the nuclei on the operated side compared with that on the intact side. No significant changes were found in the high-affinity uptake of gamma-aminobutyrate or the contents of gamma-aminobutyrate and substance P in any areas of the dorsal column nuclei. These results suggest that not only glutamate and/or aspartate but also acetylcholine may be neurotransmitter candidates for the ascending fibres terminating in the dorsal column nuclei, whereas there may be few fibres containing substance P or gamma-aminobutyrate in the dorsal column.

Animals↗
PubMed1987

Immunohistochemical studies on GABAergic neurons in the rat locus coeruleus, with special reference to their relationship to astrocytes.

Purified antisera against GABA were prepared. A few small GABAergic neurons in the rat locus coeruleus were immunohistochemically demonstrated by both the unlabeled peroxidase-antiperoxidase method and the avidin-biotin peroxidase complex method using affinity-purified GABA antibodies. The glial fibrillary acidic protein immunoreactivity in this nucleus was localized by the latter method in the astrocytal framework encircling medium-sized and small neurons as well as in straight processes. Astrocytes may play a role as energy donors to these neurons.

Animals↗
PubMed1987

Myelopathy due to diffuse thickening of the cervical dura mater in Maroteaux-Lamy syndrome: report of a case.

A rare case of diffuse thickening of the cervical dura mater leading to cord compression in Maroteaux-Lamy syndrome (mucopolysaccharidosis VI) is reported. Spinal computed tomographic scans after intrathecal metrizamide injection and magnetic resonance images are shown. This condition presents as cervical myelopathy. Early decompression can be beneficial for patients with this infrequent metabolic disorder.

Adult↗