Search PubMed⌕ Search

Biomedical subjects

K Nagashima

Publications and source records attributed to K Nagashima.

At least 289 records · Page 16Linked to original sources
PubMed1994

Quantitative analysis of rod-cored vesicles and dense granules of large granular lymphocytes in the liver, spleen, and peripheral blood of rats.

Large granular lymphocytes (LGL) comprise a natural defense system in the liver and exert an inhibitory effect on tumor cell metastasis. In order to demonstrate the maturation of LGL in the liver from the morphological aspect, we evaluated electron-microscopically the frequency of 0.2 micron vesicles (rod-cored and "empty" vesicles) and dense granules in LGL from the liver, spleen, and peripheral blood of the rat. Both of these cell organelles are characteristic to LGL and may relate to natural killer-mediated cytolysis. On the average, there were 12.7 of the 0.2 micron vesicles and 4.3 rod-cored vesicles (RCV) per cell section in the liver, 6.6 0.2 micron vesicles and 1.6 RCV in the spleen, and 8.6 0.2 micron vesicles and 0.9 RCV in the peripheral blood. The number of 0.2 micron vesicles per cell section ranged from 0 to 19 with the exception of a few higher instances. Therefore, LGL were divided into vesicle-rich (> 9 0.2 micron vesicles per cell section) and vesicle-poor (< 8 per cell section) populations. Hepatic LGL consisted mainly of a vesicle-rich population while splenic LGL consisted mainly of a vesicle-poor population, and peripheral blood contained equal proportions of both populations. In addition to diversity with regard to the number of 0.2 micron vesicles, LGL obtained from various organs also displayed heterogeneity in the number and size of dense granules.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Analysis of virus-cell binding characteristics on the determination of Japanese encephalitis virus susceptibility.

The susceptibility of fourteen established cell lines to infection with Japanese encephalitis virus (JEV) was assayed using an indirect fluorescent antibody technique. In kinetic studies, the degree of binding and internalization of JEV allowed the identification of high susceptibility and low-susceptibility cells. Scatchard analysis showed that JEV specifically bound to high-susceptibility Vero cells with greater affinity than to low-susceptibility NRK cells. Microinjection of viral genomic RNA into NRK cells induced highly efficient production of viral antigen and infectious virions. A hemagglutinin-inhibiting monoclonal antibody against JEV (MAb 301) inhibited the binding of JEV to the Vero and NRK cells. JEV was found to bind to a 74K molecule present in the membrane fraction of Vero cells and this binding was inhibited by MAb 301. Importantly, the 74K molecule was not detected in the membrane faction of NRK cells. These results suggest that early events in the JEV-cell interaction influence the susceptibility of cells to infection, and in particular suggests that the 74K molecule may be a possible candidate or component of the cellular receptor for JEV.

Animals↗
PubMed1994

Inhibition of myelin formation by HIV-1 gp120 in rat cerebral cortex culture.

To study the role of HIV-1 gp120 in loss of myelin in HIV encephalopathy, the binding of gp120 to various types of neural cells and its effects on myelination were examined in rat primary brain culture. Double-staining of cultured cells with gp120 and specific antibodies for different neural cell types showed that gp120 bound to most of the galactocerebroside (GalC)-positive oligodendrocytes, a small population of type-2-like astrocytes and a few small neurons. Gp120 did not bind to type-1-like astrocytes, most neurons, or to macrophage/microglia. To assay myelination, cells were bathed in a myelination medium containing chick embryo extract and high glucose, with or without gp120. Seven days after the application, myelination in the culture was observed morphologically and by staining with anti-myelin basic protein (MBP) antibody, and was found to be significantly inhibited by the addition of gp120 (50-100 nM). The processes of oligodendrocytes were reduced in length and arborization relative to the control, but MBP production by oligodendrocytes was unaffected. These results show that gp120 can cause a functional disorder of oligodendrocytes and thus could underlie the diffuse loss of myelin sheaths of HIV encephalopathy.

Animals↗
PubMed1994

Occurrence of multiple JC virus variants with distinctive regulatory sequences in the brain of a single patient with progressive multifocal leukoencephalopathy.

We established 99 JC virus (JCV) DNA clones directly from the brain of a single patient with progressive multifocal leukoencephalopathy (PML). Based upon restriction patterns, the cloned viral DNAs were classified into two major groups (NY-1A and -1B) containing 53 and 35 clones, respectively, and several minor groups containing one or a few clones. The regulatory sequences of representative clones were compared with the archetypal regulatory sequence, which has been detected in JCV DNAs cloned from the urine of healthy and nonimmunosuppressed individuals. The regulatory sequence of NY-1B had the two structural features common to most PML-type regulatory regions, duplication and deletion of specific segments in the archetypal sequence, while that of NY-1A contained a small deletion and an insertion of a 29-bp sequence originating from the early region of the JCV genome. A regulatory region similar to that of NY-1A has never been detected in JCV isolates obtained thus far.

AIDS-Related Opportunistic Infections↗
PubMed1994

Regeneration of mesenteric lymphatic vessels in a new experimental model of orthotopic intestinal transplantation in rats.

A new experimental model of orthotopic intestinal transplantation was performed using microsurgical techniques in rats; the physiological flow of blood, lymph, and food was reconstructed. Regeneration of mesenteric lymphatic vessels, which plays an extremely important role in lipid absorption of the transplanted intestine, was studied by mesenteric lymphangiography. Regeneration of mesenteric lymphatic vessels was first confirmed on the seventh postoperative day by mesenteric lymphangiography, and favorable regenerative patterns, without obstruction, were observed on the 32nd, 58th, and 93rd postoperative days.

Animals↗
PubMed1994

Altered peptidase and viral-specific T cell response in LMP2 mutant mice.

MHC class I molecules present peptides generated by processing of endogenously synthesized proteins to CD8+ T lymphocytes. Recently, large proteolytic complexes, termed proteasomes, were implicated in antigen processing. Two proteasomal subunits, LMP2 and LMP7, are encoded within the MHC class II region, but their precise role in antigen processing is unknown. We have generated mice that harbor a disruption in their LMP2 gene. Proteasomes purified from spleen and liver of these mutant mice exhibit altered peptidase activities, and antigen-presenting cells showed reduced capacity to stimulate a T cell hybridoma specific for H-2Db plus a nucleoprotein epitope of an influenza A virus. The mutant mice have reduced (60%-70% of wild type) levels of CD8+ T lymphocytes and generate 5- to 6-fold fewer influenza nucleoprotein-specific cytotoxic T lymphocyte precursors. These findings indicate that LMP2 influences antigen processing.

Animals↗
PubMed1994

Relationship between bladder neck diameter and hydraulic energy at maximum flow.

A pressure-flow study was performed with a 5-micro-tip transducer catheter in 6 normal male volunteers (bladder neck diameters 0.80 cm. or larger) and 13 male subjects suspected of having bladder neck contracture. Intraurethral pressure was measured at various sites in the urethra at maximum flow to calculate hydraulic energy at these sites using the Bernoulli equation. When the subjects were divided into 2 groups (1 group with a bladder neck diameter of 0.73 cm. or larger and 1 with a bladder neck diameter of 0.60 cm. or smaller), the relative value of energy (ratios to the initial energy generated in the bladder) at the external urethral sphincter was significantly (p < 0.01) greater in the former than in the latter group. Therefore, the "flow rate controlling zone" lies at the external urethral sphincter in the former group and at the bladder neck in the latter group.

Humans↗
PubMed1994

Primary pulmonary choriocarcinoma in a four month old boy complicated with precocious puberty.

A four month old boy with pulmonary choriocarcinoma, showing iso-sexual precocious puberty is reported. His serum human chorionic gonadotropin (HCG) was highly elevated. A round isolated tumor in the right lung, found by chest X-ray, magnetic resonance imaging and gallium scintigraphy, was removed surgically a month and a half after clinical manifestations were noticed. It was determined to be choriocarcinoma on the basis of histological findings and positive HCG on histochemical examination. Skull irradiation and chemotherapy (cisplatinum, vinblastine and bleomycin) had only a transient effect on reducing tumor size and normalizing the serum level of HCG. This case suggests that a more effective treatment regimen needs to be established.

Choriocarcinoma↗
PubMed1994

Effect of ageing on ultrastructure of slow and fast skeletal muscle tendon in rabbit Achilles tendons.

This reports presents the changing morphological characteristics of collagen and fibroblasts in the soleus and gastrocnemius muscle tendon of female Japanese white rabbits with ageing. The fibroblasts decreased in number per 37 microns 2 with ageing in each group, and their morphology became longer and more slender through ageing. The mean fibril area and diameter of the collagen fibrils of soleus muscle tendon (SMT) and lateral gastrocnemius muscle tendon (GMT) in 8- to 10-month old rabbits were significantly higher than those of 3-wk-old rabbits during growth (P < 0.01). The mean area and diameter of collagen fibrils of SMT and GMT decreased during senescence: the values for 4- to 5-yr-old rabbits were lower than those for 8- to 10-month-old rabbits, but the difference was not significant. Statistically significant differences in fibril area and diameter between the SMT and GMT were not found during ageing. The number of thick fibrils increased during growth, but decreased in senescence. There were more thin fibrils (30-60 nm) in the 3-wk-old rabbits than in the 8- to 10-month old and 4 to 5-yr-old groups, and the large-diameter collagen (300-360 nm) was more abundant in the 8- to 10-month-old group than in the 3-wk-old and 4- to 5-yr-old groups. Differences in fibril size between slow and fast muscle tendons were not observed during ageing.

Achilles Tendon↗
PubMed1994

Function of the cytoplasmic domain of a retroviral transmembrane protein: p15E-p2E cleavage activates the membrane fusion capability of the murine leukemia virus Env protein.

In the murine leukemia viruses (MuLVs), the Env complex is initially cleaved by a cellular protease into gp70SU and pre15ETM. After the virus particle is released from the cell, the C-terminal 16 residues are removed from the cytoplasmic domain of pre15E by the viral protease, yielding the mature p15ETM and p2E. We have investigated the function of this cleavage by generating a Moloney MuLV mutant, termed p2E-, in which the Env coding region terminates at the cleavage site. This mutant synthesizes only the truncated, mature form of TM rather than its extended precursor. When cells expressing this truncated Env protein are cocultivated with NIH 3T3 cells, they induce rapid cell-cell fusion. Thus, the truncated form, which is normally found in virions but not in virus-producing cells, is capable of causing membrane fusion. We conclude that the 16-residue p2E tail inhibits this activity of Env until the virus has left the cell. p2E- virions were found to be infectious, though with a lower specific infectivity than that of the wild type, showing that p2E does not play an essential role in the process of infection. Fusion was also observed with a chimeric p2E- virus in which gp70SU and nearly all of p15ETM are derived from amphotropic, rather than Moloney, MuLV. In a second mutant, an amino acid at the cleavage site was changed. The pre15E protein in this mutant is not cleaved. While the mutant Env complex is incorporated into virions, these particles have a very low specific infectivity. This result suggests that the cleavage event is essential for infectivity, in agreement with the idea that removal of p2E activates the membrane fusion capability of the Env complex.

Amino Acid Sequence↗
PubMed1994

Fibronectin synthesis bioactivity in human breast milk.

To evaluate the effect of milk feeding on fibronectin in the perinatal period, fibronectin synthesis bioactivity (FnSA) in human breast milk was examined. FnSA was measured by bioassay using the cell-lined fibroblast. For the characterization of the FnSA, the milk samples were chromatographed. In gel chromatography (Sephadex G-100), three fractions of FnSA were detected. Two fractions overlapped with those of immunoreactive epidermal growth factor (ir-EGF). The other was present in the low-molecular-weight portion. In the high-performance liquid chromatography, two of four fractions with FnSA presented ir-EGF. One of two fractions with FnSA in heparin-binding affinity chromatography almost coincided with the portions of basic brain fibroblast growth factor (ir-bFGF). From these findings, we speculated that human milk has the bioactivity of fibronectin synthesis and it is composed of EGF, FGF, and unknown low-molecular-weight factors. Although the clinical meanings of FnSA have not been clarified, our data indicate a new characteristic of human milk.

Biological Assay↗
PubMed1994

P300 event-related potentials in epileptic children.

To evaluate the cognitive function of epileptic children, we examined P300 in 50 patients, 32 with idiopathic generalized epilepsy (IGE) and 18 with temporal lobe epilepsy (TLE), and 39 normal children. There were significant negative correlations between age and P300 latencies at Pz and Cz in normal controls. For data analysis, we used the age-corrected latency, which was calculated as the interval between the actual and predicted P300 latencies. The predicted latency was calculated with the regression equation as the relationship between P300 latency and age in normal controls. The age-corrected P300 latencies recorded from Pz and Cz were significantly longer in patients with IGE (41.5 +/- 13.1, 42.0 +/- 12.5) than in control subjects (0 +/- 7.5, 0 +/- 7.9). There were no significant differences in age-corrected P300 latencies between patients with TLE (21.2 +/- 17.6, 31.5 +/- 17.0) and controls, or IGE and TLE. Recently, it was considered that the mesencephalic reticular formation and thalamus may play major roles in the genesis of generalized epilepsy, so we speculate that dysfunction of these systems may contribute to the prolongation of P300 in children with idiopathic generalized epilepsy.

Adolescent↗
PubMed1994

Familial congenital hypopituitarism with central diabetes insipidus.

Congenital hypopituitarism (CH) presenting with central diabetes insipidus is typically associated with midline facial deformities or ophthalmological abnormalities. We present three brothers with CH and central diabetes insipidus not associated with any of these predisposing conditions. All three subjects presented with clinical features typical for CH (neonatal hypoglycemia, short stature, protruding forehead, and microgenitalia). All had hypoplastic genitalia indicating in utero gonadotropin deficiency, and all had complete GH deficiency. One represented low levels of thyroid hormones and TSH, indicating central hypothyroidism. Water deprivation examination in two of the brothers demonstrated complete arginine vasopressin deficiency in one and partial deficiency in the other. Magnetic resonance imaging indicated absence of the pituitary stalk, severe hypoplastic anterior pituitary in all three brothers, and absence of any posterior pituitary gland in two of the three. The other sibling had an ectopic posterior pituitary. This first report of familial CH with central diabetes insipidus may represent a previously unknown midline anomaly and provide new insights into the genetic control of pituitary and hypothalamic development.

Antibodies↗
PubMed1994

Somatostatin-related peptides isolated from the eel gut: effects on ion and water absorption across the intestine of the seawater eel.

Four somatostatin-related peptides were isolated from eel guts. Two of them were the same as eel SS-25II (eSS-25II) and eel SS-25I (eSS-25I) isolated from European eel pancreas. The remaining two peptides were C-terminal tetradecapeptides (eSS-14II and eSS-14I) of eSS-25II and eSS-25I, respectively. These four peptides all enhanced the serosa-negative transepithelial potential difference and short-circuit current across the seawater eel intestine after pretreatment with isobutylmethylxanthine, serotonin (5-HT) and methacholine, an agonist of acetylcholine (ACh). Among these peptides, eSS-25II was the most potent enhancer, followed by eSS-25I and eSS-14II. Since the large peptide (eSS-25II) acts at a lower concentration than the small somatostatin (eSS-14II), the 11 N-terminal amino acid residues seem to potentiate somatostatin action in the eel intestine. In contrast, eSS-14II was more potent than mammalian SS-14, indicating that the three amino acid residues (Tyr18, Gly21, Pro22) in the C-terminal portion also contribute to the potency of somatostatin. Endogenous somatostatin (eSS-25II) activated net Na+, Cl- and water fluxes across the seawater eel intestine. This stimulatory action was not inhibited by tetrodotoxin or yohimbine, an adrenergic antagonist, indicating that eSS-25II does not act through neuronal firing or through catecholamine release. Thus, eel somatostatins may act directly on the enterocytes, but on a distinct receptor from that for adrenaline, to antagonize the inhibition of NaCl and water absorption by 5-HT and ACh in the seawater eel intestine.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Effects of KW-3902, a novel adenosine A1-receptor antagonist, on cephaloridine-induced acute renal failure in rats.

We investigated the possible renal protective effects of KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine), a selective and potent adenosine A1-receptor antagonist, against cephaloridine (CER)-induced acute renal failure (ARF) in rats. ARF was induced by intravenous injection of CER at a dose of 600 mg/kg body weight. KW-3902 at doses higher than 0.01 mg/kg (p.o.) dose-dependently attenuated the decrease of creatinine clearance and the increase of proteinuria in rats with CER-induced ARF. In contrast, furosemide and trichlormethiazide (TCM) increased urinary protein and aggravated the serum parameters. These results suggest that KW-3902 has some advantages over furosemide and TCM when used in combination with CER. In the diuretic study in the rats with established ARF induced by CER, KW-3902, furosemide and TCM caused a significant increase in sodium excretion, whereas acetazolamide was ineffective. These results suggest that the proximal tubule is functionally damaged in rats with CER-induced ARF, in accord with the histological observation demonstrating the degeneration of the proximal tubule. From the fact that KW-3902 induces diuretic action even in CER-induced ARF, it is suggested that KW-3902 acts, directly or indirectly, on the proximal tubule or other tubular sites in the kidney, resulting in the diuretic effect.

Acute Kidney Injury↗
PubMed1994

The significance of herpes viral latency in the spiral ganglia.

To better understand the pathogenesis of idiopathic sudden hearing loss (ISHL), the possibility of latent virus infection in the spiral ganglion cell was considered. Only few spiral ganglion cells showed positive viral antigen after systemic guinea pig-specific cytomegalovirus (GPCMV) inoculation indicating the absence of hearing loss but the possibility of a subsequent latent infection. By using a modern molecular biological technique we have detected the herpes simplex virus type-1 (HSV-1) DNA in human spiral ganglia. The concept of establishing viral latency in the spiral ganglion cells with periods of reactivation fits with the clinical picture seen in ISHL, even though the mechanism of reactivation still remains unclear.

Adult↗
PubMed1994

[Left ventricular-right atrial shunt with bacterial and rheumatic endocarditis of tricuspid valve].

A 14-year-old boy who was operated on for left ventricular-right atrial shunt with bacterial and rheumatic endocarditis of the tricuspid valve (TV) is reported. The patient was pointed out perimembranous ventricular septal defect (VSD) at 4-month old and had complaint of occasional high fever for a half year. The echocardiography showed a vegetation at the TV. The vegetation did not disappear despite of administration of antibiotics for 2 weeks, and pulmonary embolism occurred. Then, the patient underwent resection of the vegetation and direct closure of VSD. The left ventricular-right atrial shunt was formed by the direct communication between VSD below TV annulus and the perforation of septal leaflet of TV adhered to the ventricular septum due to bacterial and rheumatic endocarditis. Earlier operation is needed for this type of case because antibiotics is not effective for the valvular disease.

Adolescent↗