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Biomedical subjects

M Nishikawa

Publications and source records attributed to M Nishikawa.

At least 919 records · Page 51Linked to original sources
PubMedDate not supplied

A case of large neonatal arteriovenous malformation with heart failure. Color Doppler sonography, MRI and MR angiography as early non-invasive diagnostic procedures.

We report a case of a large arteriovenous malformation (AVM) of neonatal onset with heart failure. Transfontanel color Doppler sonography revealed abnormal vessels in the early stage of the investigation. Magnetic resonance imaging (MRI) revealed numerous flow voids suggesting abnormal vessels, and magnetic resonance angiography (MRA) disclosed numerous bizarre abnormal vessels. Color Doppler sonography is a convenient and appropriate procedure for the early bedside diagnosis of neonatal AVMs. MRI and MRA can replace cerebral angiography for the diagnosis of neonatal AVMs.

Arteriovenous Fistula↗
PubMedDate not supplied

Retroperitoneal schwannomas simulating adrenal tumors.

Tumors in the area of the adrenal were detected by chance in two patients who underwent a regular physical check-up. On arteriography the tumors were found to be fed by the adrenal artery. The diagnosis was retroperitoneal schwannoma, but in both patients it was difficult to differentiate the schwannoma from an adrenal tumor preoperatively.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Phorbol ester-induced activation of human platelets is associated with protein kinase C phosphorylation of myosin light chains.

Phosphorylation of the 20,000 molecular weight (MW) light chain of platelet myosin is associated with the activation of platelets and subsequent release of platelet granules, and the protein kinase catalysing this phosphorylation has been identified as the Ca2+/calmodulin-dependent enzyme, myosin light chain kinase. Tumour-promoting phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA), which activate Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C), can also cause platelet aggregation and phosphorylation of a 20,000-MW peptide in blood platelets. It was therefore of interest to ascertain whether the 20,000-MW peptide phosphorylated in platelets was the light chain of myosin and whether TPA-induced phosphorylation of the 20,000-MW peptide could be differentiated from thrombin-induced phosphorylation. We now report that TPA-induced activation of platelets is associated with the phosphorylation of the 20,000-MW light chain of myosin, that it appears to be mediated mainly through protein kinase C and that the site phosphorylated in the myosin light chain is distinct from that phosphorylated by myosin light chain kinase.

Blood Platelets↗
PubMedDate not supplied

Extent of cadmium accumulation and its effect on essential metals in liver, kidney, and body fluids.

Cadmium was injected sc into female Wistar rats at a dose of 3.0 mg Cd/kg body weight, 4 times a week for 1, 2, 3, 4, 5, and 6 wk. Cadmium and five essential metals in the livers and kidneys were determined simultaneously by inductively coupled plasma-atomic emission spectrometry. Concentration of cadmium in the livers increased linearly up to 3 wk, remained at an almost constant and highest value (440 micrograms Cd/g wet liver) for the following 2 wk, and then decreased. The difference between cadmium in the whole livers and cadmium bound to heat-stable proteins was wider during the plateau than during the other periods. Cadmium in the kidneys was close to a plateau after 6 wk of injections. Concentrations of zinc in the livers and copper in the kidneys changed dramatically with injections of cadmium, and the changes were related to the changes in concentrations of the two metals in plasma and urine. Concentration of iron in the kidneys decreased with injections of cadmium. The content ratio of calcium to magnesium was high in the case of liver edema and was suggested to be an indicator. Cadmium in urine was assumed to originate from the liver in the case of high accumulation of the metal.

Animals↗
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Determination of bromvalerylurea and its metabolites in biological samples by frit-fast atom bombardment liquid chromatography-mass spectrometry.

A simple, rapid, and sensitive method which allows us to simultaneously determine bromvalerylurea (BVU) and its three metabolites (3-methylbutyrylurea [MVU], alpha-(cystein-S-yl)isovalerylurea [CVU], and alpha-(N-acetylcystein-S-yl)isovalerylurea [AcCVU]) was investigated by frit-fast atom bombardment liquid chromatography-mass spectrometry (frit-FAB LC-MS). The LC-MS analysis was performed after the solid-phase extraction from tissue and urine samples with a Sep-Pak C18 cartridge. Tissue homogenates and urine were adjusted to pH 4.0 and applied to the cartridges. The retained BVU and its metabolites were eluted from the cartridge with 2 mL of acetonitrile/10 mM ammonium acetate buffer (pH 3.5, 50:50, v/v). The eluate was analyzed by LC-MS, which employs a semimicro type L-column ODS column. The proposed conditions are as follows: mobile phase A, 0.4% glycerol in acetonitrile/10 mM ammonium acetate buffer (pH 3.5) (5:95, v/v); mobile phase B, 0.4% glycerol in acetonitrile; elution mode, linear gradient, 100% A (5 min) to 100% B in 15 min; flow rate, 0.2 mL/min; split ratio, 1:40. Extraction recoveries of BVU and its metabolites were 91.90-97.79% from the spiked liver homogenate and 89.68-96.13% from the spiked urine. The detection limits ranged from 10 to 25 ng/g in selected ion monitoring mode.

Animals↗
PubMedDate not supplied

Discrimination of dimethylamphetamine and methamphetamine use: simultaneous determination of dimethylamphetamine-N-oxide and other metabolites in urine by high-performance liquid chromatography-electrospray ionization mass spectrometry.

A simple and sensitive method by high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) has been investigated for the simultaneous determination of dimethylamphetamine (DMA), its specific yet labile main metabolite dimethylamphetamine-N-oxide (DMAO), and other metabolites, methamphetamine (MA) and amphetamine (AP), in urine. A combination of Bond Elut SCX columns for the solid-phase extraction of urine and a semi-micro SCX column for LC separations provided satisfactory results. The use of acetonitrile/5mM ammonium acetate buffer adjusted to pH 4 (65:35, v/v) as the mobile phase at a flow rate of 0.2 mL/min was found to be the most effective. The detection limits were 5 ng/mL for DMAO, 10 ng/mL for DMA and MA, and 50 ng/mL for AP in the SIM mode.

Central Nervous System Stimulants↗
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Does a porcine hepatocyte hybrid artificial liver prolong the survival time of anhepatic rabbits?

To examine cultured porcine hepatocytes as a bioreactor of a hybrid artificial liver (HAL) in rabbits, a small version of a multiplated HAL was manufactured. In vitro and ex vivo studies were performed to evaluate the small HAL. The HAL consisted of 50 glass plates (10 x 5 x 0.04 cm each) on which porcine hepatocytes were cultured in a monolayer at confluent cell density. After 2 days of standard cultivation, the glass plates with hepatocytes were placed in the module and were used for studies. The module contains about 5 grams of hepatocytes (1/10 of 2 kg.bw rabbit liver). After undergoing perfusion culture for 5 days, the HAL showed satisfactory hepatic function. Glucose and urea were synthesized at the rate of 4.06 +/- 0.7 mg/module/hr and 0.62 +/- 0.09 mg/module/hr, respectively, and loaded ammonia was metabolized at the rate of 1.29 +/- 0.26 mg/module/hr. Ex vivo extracorporeal plasma perfusion studies revealed that the module with cultured porcine hepatocytes, which were heterogeneous to rabbits, showed a tendency to prolong the survival time of anhepatic rabbits. These results indicate that the HAL system, using multiplated porcine hepatocyte monolayers, is a promising artificial liver support system for clinical cases.

Animals↗
PubMedDate not supplied

Comparative studies of glycoprotein Ib in heparin coated and nonheparin coated extracorporeal circulation circuits.

Contact between blood and artificial materials has various effects on blood. Impairment of platelet function is an especially important and well known effect, but its precise mechanism is not clearly understood. The authors constructed a circulation model to investigate the effect of extracorporeal circulation on platelet membrane glycoproteins (GPs), especially GP Ib, and to compare the changes in GP Ib in heparin coated (group C) and nonheparin coated (group N) circuits. As determined by flow cytometry, GP Ib in both groups decreased on initiating circulation, but the decrease in group N was significantly larger than that in group C. There was no observed change in GP IIb/IIIa levels in either group. The extent of shear stress induced platelet aggregation significantly decreased during circulation in both groups. Decreases in the extent of shear stress induced platelet aggregation were significantly less with the use of heparin coated circuits. In addition, the amount of GP Ib in the high speed pellet decreased progressively during circulation in both groups. In contrast, the amount of GP Ib in the Triton insoluble (low speed) pellet increased dramatically during circulation. However, expression of GP Ib in the Triton soluble platelet fraction was low in both groups. From the results, it was concluded that the cause of the decrease in platelet function during extracorporeal circulation is attributable to the internalization of GP Ib from the platelet surface inside the platelet. It also can be said that a heparin coated circuit is one effective means of controlling this change.

Blood Platelets↗
PubMedDate not supplied

Differentiation between hepatoma and hemangioma with inversion-recovery snapshot FLASH MRI and Gd-DTPA.

Thirty-eight patients with focal liver tumors (20 hepatomas, 18 hemangiomas) were studied by dynamic sequential inversion recovery (IR) snapshot fast low angle shot (FLASH) MR imaging with Gd-DTPA. Immediately after 0.05 mmol/kg Gd-DTPA was administered intravenously for 2-3 s followed by flushing with normal saline for 4-5 s, 10 images were obtained in the first 20 s (time zero is the end of flush, early phase). Then, one image every 30 s from 1 to 3 min (late phase) and images at 5 min and 7 min (delayed phase) were obtained serially. Hepatomas showed total enhancement in 18 of 20 patients in the early phase, and isointense or low intensity enhancement with respect to the surrounding liver parenchyma in 18 patients in the late to delayed phases. Hemangiomas showed peripheral enhancement in 14 patients in the early phase, but did not show total enhancement (except for two hemangiomas less than 3 cm in size) in the early phase, and showed high intensity enhancement in 15 patients in the late phase. Ninety percent of hepatomas and 82% of hemangiomas showed their characteristic enhancement patterns in the early to delayed phases. We conclude that dynamic sequential IR snapshot FLASH MR images enhanced with Gd-DTPA can facilitate differentiation between hepatomas and hemangiomas.

Aged↗
PubMedDate not supplied

Protective effect of docosahexaenoic acid against retinal ischemic injury: an electroretinographic study.

PURPOSE: To determine whether docosahexaenoic acid (DHA) can reduce the retinal damage induced by transient retinal ischemia. METHODS: Retinal ischemia was induced by increasing intraocular pressure (IOP). Retinal circulation was restored by lowering IOP. An intraperitoneal injection of 1,000 mg/kg of DHA-ester (DHA-E) was given 5 h before the ischemia. Electroretinograms were recorded just before the ischemia and at 60-min intervals up to 4 h after circulation was restored. RESULTS: The ratio of the amplitudes after the ischemia to that just before ischemia was significantly higher in eyes administered DHA-E than in controls at each time point (p < 0.01). CONCLUSION: DHA-E is effective in protecting the retina against transient retinal ischemia.

Animals↗
PubMedDate not supplied

Alterations in alpha adrenergic receptors in human cerebral arteries after subarachnoid hemorrhage.

The nature of alpha adrenergic receptors in human cerebral arteries was characterized and alteration of these receptors after subarachnoid hemorrhage (SAH) was examined using a radioligand binding assay. The specific 3H-prazosin binding to human cerebral arteries was saturable and of high affinity (KD = 4.1 nM) with a Bmax of 92 fmol/mg protein. Specific 3H-yohimbine binding to these tissues was also saturable and of high affinity (KD = 23 nM) with a Bmax 250 fmol/mg protein. IC50 values of adrenergic agents for 3H-prazosin binding were as follows: prazosin, 1.2 X 10(-10) M; phentolamine, 1.3 x 10(-6) M; yohimbine, 1.2 x 10(-5); norepinephrine, 4.9 x 10(-4) M; epinephrine greater than 1 x 10(-3) M. IC50 values of adrenergic agents for 3H-yohimbine binding were as follows: phentolamine, 1.7 x 10(-7) M; yohimbine, 4.2 x 10(-7) M; prazosin, 1.9 x 10(-5) M; epinephrine, 4.4 x 10(-5) M; norepinephrine, 7.9 x 10(-4) M. KD and Bmax of 3H-prazosin and 3H-yohimbine binding after SAH were compared with findings in the non-SAH group. KD and Bmax of 3H-prazosin binding of SAH group were 6 +/- 3 nM and 90 +/- 10 fmol/mg protein, respectively (N = 3). KD and Bmax of 3H-yohimbine binding of SAH group were 42 +/- 6 nM and 460 +/- 30 fmol/mg protein, respectively (N = 5). On the other hand, KD and Bmax of 3H-prazosin binding in the non-SAH group were 4 +/- 1 nM and 90 +/- 20 fmol/mg protein, respectively (N = 5), KD and Bmax of 3H-yohimbine binding of non-SAH group were 20 +/- 5 nM and 260 +/- 30 fmol/mg protein, respectively (N = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Treatment with bifemelane for optic nerve damage following high intraocular pressure in rat eyes.

This study found that pretreatment with 4-(o-benzylphenoxy)-N- methylbuty-lamine hydrochloride (bifemelane hydrochloride, Celeport) reduced ischemia-reperfusion injury in rat eyes. Bifemelane (25 mg/kg) was injected intraperitoneally 30 minutes before an ischemic insult, then acute ischemia of the retina and optic disc was induced by increasing intraocular pressure to 110 mmHg for 45 minutes. After one week, the axonal count of the optic nerve was investigated using electron microscopy. The control group consisted of vehicle-treated eyes which received normal saline. The axon count was 93.4 +/- 7.9 for the bifemelane treated group, and 79.2 +/- 6.4 for the controls. The axon count in the treated group was significantly higher. These results suggest that bifemelane, which prevents cerebral nerve cell damage from ischemia, can reduce ischemic retinal nerve cell injury.

Animals↗
PubMedDate not supplied

An adult case of acute lymphoblastic leukemia with necrotizing leukoencephalopathy.

A 19-year-old man with common acute lymphoblastic leukemia (ALL) developed necrotizing leukoencephalopathy (NL) after extensive chemotherapy and irradiation. Clinicians should exercise care in the treatment of leukemia, since chemotherapy has shown a trend of becoming more intensive, and the survival time of patients with leukemia is being extended.

Adult↗
PubMedDate not supplied

Pathogenesis of encephaloschisis in retinoic-acid-treated hamster embryos I: a morphometric study of the craniofacial structures.

The severity of the developmental disorders of the paraxial mesoderm and neuroectoderm must objectively be compared to determine which of the two structures is more deeply involved in the pathogenesis of encephaloschisis. In the present study, hamster fetuses were obtained from dams that had been treated with retinoic acid, and divided into two groups: fetuses with encephaloschisis and those without apparent external malformations in the cranium and face. Mid-sagittal serial sections of the head were prepared, histologically processed, and utilized for the reconstruction of the profile of the head structures. Using this reconstructed profile, we measured the length of the skull base bone structures (basisphenoid and basiocciput), which develop from the paraxial mesoderm, brain structures (mesencephalon and metencephalon), which develop from the neuroectoderm, and facial bone structures (nasal septum and hard palate), which develop from cephalic neural crest cells. The measured length of each structure was compared between the treated and control groups. It was found that treatment with retinoic acid resulted in significantly (P < 0.05) shortened lengths of the skull base bone structures both in fetuses with encephaloschisis and those without apparent external malformations in the cranium and face. In the brain structure of fetuses without encephaloschisis, as well as in the facial bone structures, however, this shortness was not observed. These results suggest that developmental disorders in the paraxial mesoderm may play an important role in the pathogenesis of encephaloschisis.

Animals↗
PubMedDate not supplied

Dynamic MR studies of hepatocellular carcinoma with portal vein tumor thrombosis.

Gd-DTPA enhanced dynamic MR studies were evaluated in six patients with hepatocellular carcinoma associated with portal vein tumor thrombus. The portal vein tumor thrombus was clearly visualized as a low intensity lesion. The hepatic segment supplied by the portal vein showed high intensity, probably due to decreased portal blood flow and compensatory arterial blood flow. Tumors located in this segment were shown as areas of relatively low intensity compared with segmental high intensity areas. Thus dynamic MR study was found to be a useful method for differentiating the tumor from the surrounding nontumorous tissue with decreased portal blood flow.

Adult↗
PubMedDate not supplied

[Microorganism "Montezuma" of the order Rickettsiales: the potential causative agent of tick-borne disease in the Far East of Russia].

A new microorganism, tentatively named "Montezuma" was detected in ticks and in specimens (blood, bioptic specimens of the primary affect) taken from patients with an acute fever disease, etiologically linked with the bites of Ixodes ticks in the Far East of the Russian Federation. After sequencing the products of the amplification of DNA isolated from ticks with wide-spectrum primers new primers were developed, highly specific to the unusual sequence thus obtained. The study revealed that ticks of the species Ixodes persulcatus (97%) and Haemophysalis concinnae (5%) contained DNA of this microorganism. The same DNA was detected in materials taken from the patients. The phylogenetic analysis of the gene showed that this organism formed an independent and well defined branch within the order Rickettsiales. The nearest homology (89%) was observed with recently detected endosymbiotes Acanthamoeba. The similarity with their relatives from the families Rickettsiaceae and Anaplasmataceae of the order Rickettsiales was within 81-86%, which made it possible to infer the existence of, probably, only a new genus, but also a family. The isolated DNA belonged, supposedly, to the new microoganism which caused a tick-borne disease in humans, transmitted through bites of Ixodes ticks, and was, supposedly, widely spread in the southern area of the Khabarovsk Territory.

Acute Disease↗
PubMedDate not supplied

Primary round cell liposarcoma of the omentum. A case report.

Liposarcomas are the most common of the malignant soft tissue tumors arising in the mediastinum and retroperitoneum. We have treated patients for round cell liposarcoma, an unusual histologic subtype, which is reported to be histologically mistaken for Ewing's sarcoma, lymphoma and other round cell neoplasms. The successful resection of a 2,300-g round cell liposarcoma of the omentum was recently performed at our hospital. Ultrastructural observations of this tumor are characterized by massive proliferation of the mitochondria in addition to the presence of lipid vacuoles in tumor cells. To our knowledge, no description of substantial mitochondrial proliferation in round cell liposarcoma has appeared previously in the literature; therefore, this is the first case report of histopathologic, cytopathologic and electron microscopic observations on this extremely rare tumor.

Female↗