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Biomedical subjects

H Sakata

Publications and source records attributed to H Sakata.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Serratia marcescens brain abscess in a newborn].

The patient was born by emergency cesarean section for fetal distress at 35 weeks gestation with a weight of 2740 g. The early neonatal course was complicated by transient tachypnea and renal failure. He was receiving oxygen and diureticus in incubator for 5 days and his condition was very improved on day 5. On day 7 he became lethargy and there was inability to tolerate feeding. Investigation of the cerebrospinal fluid revealed 8,000 leukocytes/microliter. S. marcescens was grown from cultures of both blood and cerebrospinal fluid. Treatment was started with cefotaxime and ampicillin every 6 hour. On day 14 the CT showed a brain abscess located parietooccipitally on the left side and diffuse infarction on the right side. On day 14 and 23 recurrence of increased leukocytes in the cerebrospinal fluid, high values of serum CRP and deterioration of clinical symptoms were observed. It is thought that the episodes show rupture of the abscess into the lateral ventricle. On day 55 surgical drainage was performed for the hydrocephalus. On day 110 the abscess was not found in the brain CT scan. His psychomotor development 3 years later was equivalent to two years old and he had secondary epilepsy.

Brain Abscess↗
PubMed1998

Measles virus attenuation associated with transcriptional impediment and a few amino acid changes in the polymerase and accessory proteins.

Measles virus (MV) isolated in B95a cells, a marmoset B-cell line, retains full pathogenicity for cynomolgus monkeys, while its derivative obtained by adaptation to the growth in Vero cells, a monkey kidney cell line, loses the pathogenic potential (F. Kobune, H. Sakata, and A. Sugiura, J. Virol. 64:700-705, 1990). Here, we show with a pair of strains, a fresh isolate (9301B) in B95a cells and its Vero cell-adapted form (9301V), that the in vivo attenuation parallels the decrease of replication and syncytium-inducing capabilities in the original B95a cells and that these in vitro phenotypes are attributable to impediment of transcription, which is already obvious at the level of primary transcription catalyzed by the virion-associated RNA polymerase. On the other hand, cell fusion assays detected no functional difference between the glycoproteins of the two viruses. Essentially the same transcriptional impediment with reduced syncytium induction following Vero cell adaptation was found with two other pairs of strains that had been similarly prepared. Nucleotide sequence comparison between the 9301B and 9301V viruses revealed that a few (at most five) amino acid changes, which sporadically took place in the polymerase (L and P proteins) and/or accessory V and C proteins, were responsible for the in vitro and in vivo attenuation through adaptation to growth in Vero cells.

Adaptation, Physiological↗
PubMed1998

LDL apheresis for arteriosclerosis obliterans with occluded bypass graft: change in prostacyclin and effect on ischemic symptoms.

To study the mechanism of efficacy of low-density lipoprotein (LDL) adsorption for arteriosclerosis obliterans (ASO), eight ASO patients without indication for bypass surgery underwent LDL apheresis twice a week for 5 weeks and the change in prostaglandin 12 (PGI2) and thromboxane A2 (TXA2) due to LDL apheresis was measured. The concentration of 6-keto-PGF1alpha, a metabolite of PGI2, in systemic venous blood significantly increased from 10.4 +/- 1.8 to 42.0 +/- 10.6 pg/mL (P<0.05) after one session of LDL apheresis, while no significant change of TXB2, a metabolite of TXA2, was encountered. The ratio of 6-keto-PGF1alpha/TXB2 also rose dramatically from 0.213 +/- 0.044 to 0.522 +/- 0.128 (P<0.05). In five patients, the ischemic clinical symptoms improved and both the concentration of 6-keto-PGF1alpha and the ratio of 6-keto-PGF1alpha/TXB2 increased significantly, whereas in three patients there was no effect on clinical symptoms and neither parameter changed. These results suggest that elevated production of PGI2 from vascular cells due to LDL apheresis might contribute to improvement of ischemic symptoms.

Aged↗
PubMed1998

A wild-type Japanese measles virus strain inducing predominant early down-regulation of CD46.

Down-regulation of CD46 secondary to stimulation with measles virus (MV) was investigated using CD46-positive cell lines and Japanese wild-type MV strains. The cells used were simian cell lines B95a and Vero in which MV strains have been adapted to be amplified, and Chinese hamster ovary (CHO) cell transfectants expressing human CD46 with (CHO(tail+)) or without (CHO(tail-)) the cytoplasmic tail. Of four Vero-adapted and three B95a-adapted MV strains, one Vero-adapted strain named Khono (KO), down-regulated CD46 within 60 min (early down-regulation) in all cell lines examined except Vero. No strains other than Toyoshima (TY), which induced early down-regulation only in CHO(tail+) cells, induced early down-regulation of CD46 in any combination. On the other hand, conventional down-regulation of CD46 was observed 24 h post-MV inoculation (late down-regulation) when cell lines used were adapted to MV strains. Thus, we concluded that there are two modes of CD46 down-regulation by MV and the unique strain KO markedly induces early down-regulation. Also, the CD46 homologue of B95a, which fails to act as a MV receptor, is down-regulated concomitantly with MV replication (>24 h) in cells principally by competent virus strains.

Amino Acid Sequence↗
PubMed1998

Para-anastomotic aneurysms: incidence, risk factors, treatment and prognosis.

BACKGROUND: The purpose of this retrospective study was to analyze the incidence, risk factors, treatment, and prognosis of para-anastomotic aneurysms. METHODS: During the period between January, 1980 and August, 1996, 511 patients underwent surgical operations for arterial diseases with grafts and were followed for more than 30 days (average: 3.5 years). The number of anastomoses was 1445 in all. Until October, 1996, 18 para-anastomotic aneurysms had been detected in 13 patients. By Kaplan-Meier's method, the incidence of para-anastomotic aneurysms at 5, 10, and 15 years was 0.8, 6.2, and 35.8%, respectively. Univariate analysis indicated that arteriosclerosis obliterans, hypertension, thromboendarterectomy and an anastomosis in the groin were significant risk factors, while stepwised multivariate analysis revealed only hypertension as significant. The mean interval from the primary operation to the diagnosis was 79 months. Ten aneurysms were operated and seven were produced by dehiscence of the anastomotic line, namety anastomotic aneurysms, and three were juxta-anastomotic aneurysms with intact anastomotic lines. Eight patients underwent resection or exclusion of the aneurysm and reconstruction with a new graft and two patients underwent a replacement of the aneurysmal autovein patch to a Dacron one and aneurysmorrhaphy of the parent aneurysmal artery. RESULTS: No recurrence has been detected. In eight patients who were followed conservatively, two died of rupture and renal failure following acute arterial occlusion. CONCLUSIONS: Since para-anastomotic aneurysms can lead to fatal complications, an enlarging or symptomatic aneurysm should be treated promptly.

Adult↗
PubMed1997

Functional and biophysical characterization of recombinant human hepatocyte growth factor isoforms produced in Escherichia coli.

Hepatocyte growth factor (HGF) is a pluripotent secreted protein that stimulates a wide array of cellular targets, including hepatocytes and other epithelial cells, melanocytes, endothelial and haematopoietic cells. Multiple mRNA species transcribed from a single HGF gene encode at least three distinct proteins: the full-length HGF protein and two truncated HGF isoforms that encompass the N-terminal (N) domain through kringle 1 (NK1) or through kringle 2 (NK2). We report the high-level expression in Escherichia coli of NK1 and NK2, as well as the individual kringle 1 (K1) and N domains of HGF. All proteins accumulated as insoluble aggregates that were solubilized, folded and purified in high yield using a simple procedure that included two gel-filtration steps. Characterization of the purified proteins indicated chemical and physical homogeneity, and analysis by CD suggested native conformations. Although the K1 and N-terminal domains of HGF have limited biological activity, spectroscopic evidence indicated that the conformation of each matched that observed when the domains were components of biologically active NK1. Both NK1 and NK2 produced in bacteria were functionally equivalent to proteins generated by eukaryotic systems, as indicated by mitogenicity, cell scatter, and receptor binding and activation assays. These data indicate that all four bacterially produced HGF derivatives are well suited for detailed structural analysis.

Circular Dichroism↗
PubMed1997

Heparin binding and oligomerization of hepatocyte growth factor/scatter factor isoforms. Heparan sulfate glycosaminoglycan requirement for Met binding and signaling.

Hepatocyte growth factor/scatter factor (HGF/SF) is a heparin-binding polypeptide that stimulates cell proliferation, motility, and morphogenesis by activation of its receptor, the c-Met tyrosine kinase. HGF/SF consists of a series of structural units, including an amino-terminal segment with a hairpin loop, four kringle domains, and a serine protease-like region. In this study, we demonstrate that the amino-terminal (N) domain retains the heparin-binding properties of full-length HGF/SF. In contrast to a previous hypothesis, selected basic amino acid residues in the hairpin loop are not critical for heparin binding, although alanine substitution at a subset of these sites markedly reduced the biological activity of the HGF/SF isoform, HGF/NK1. Covalent cross-linking experiments performed with wild-type and heparan sulfate glycosaminoglycan (HSGAG)-deficient Chinese hamster ovary (CHO) cells revealed that Met-HGF/NK1 binding was strongly dependent on HSGAG. Addition of heparin to HSGAG-deficient CHO cells not only restored ligand binding, but also increased ligand-dependent Met tyrosine phosphorylation and c-fos expression. Moreover, our results showed that heparin stimulated ligand oligomerization through an interaction with the N domain. These findings establish the importance of the N domain for heparin-ligand and ligand-ligand interactions, and demonstrate a crucial role for HSGAG in receptor binding and signal transduction.

Amino Acid Sequence↗
PubMed1997

Serum Soluble Interleukin-2 Receptor Levels in Patients with Breast Cancer.

Preoperative levels of serum soluble interleukin-2 receptor (1L-2R) were examined in 37 patients with breast cancer. We investigated the correlations of serum soluble IL-2R levels with various factors such as stage grouping, lymph node metastasis, distant metastasis, tumor size, histophthological type, estrogen receptor (ER), progesterone receptor (PgR) and CA 15-3. Serum soluble 1L-2R levels were measured with an enzyme-linked immunosorbent assay. Levels of serum soluble 1L-2R in the patients with stage III and IV breast cancer were significantly higher than those in the normal controls, and patients with stage I and II breast cancer. Preoperative levels of serum soluble IL-2R in patients with T3 and T4 were also significantly higher than those in patients with T1 and T2. Serum levels of IL-2R in patients with distant metastasis were also significantly higher than those in patients without distant metastasis. Moreover, serum levels of soluble IL-2R in patients with higher CA 15-3 were significantly higher than those in patients with normal CA 15-3 levels. We conclude that preoperative serum soluble IL-2R levels in patients with breast cancer may be a valuable parameter, especially in evaluating whether they have distant metastasis or not.

Journal Article↗
PubMed1997

Visual working memory for shape and 3D-orientation: a PET study.

In order to determine the neural substrate of working memory for shape and 3D-orientation, regional cerebral blood flow (rCBF) changes were estimated using positron emission tomography (PET). Subjects were scanned during the performance of two delayed-matching-to-sample tasks using flat polydedrical objects of different shapes and 3D-orientations presented in a virtual environment. The shape matching task was associated with activation in the occipito-temporal junction, occipito-parietal cortex and mesial frontal pole of the right hemisphere. During the orientation matching task, rCBF increased in the mesial occipito-temporal cortex, superior temporal gyrus and middle frontal gyrus of the left hemisphere. The right supramarginal gyrus was also activated. These results suggest that both visual pathways are engaged in the processing of objects presented in different orientations. The dorsal stream is involved mainly in working memory of 3D-orientation, while the ventral stream is involved especially in shape working memory.

Adult↗
PubMed1997

Intermittent claudication associated with persistent sciatic artery: report of two cases.

Two elderly women complaining of intermittent claudication complicated with persistent sciatic artery are herein reported. A direct femoral arteriogram showed hypoplasty of the superficial femoral artery and an unnatural anatomical relationship between the distal superficial femoral artery and the proximal popliteal artery, thus suggesting the presence of persistent sciatic artery. The diagnosis of persistent sciatic artery was finally made based on the aortography findings including the iliac arterial system and computed tomography (CT) scan. Magnetic resonance imaging (MRI) was helpful to demonstrate the entire image of this anomaly in cases with non-thrombolized sciatic artery. These diagnostic methods were useful in designing the optimal surgical strategy. The first case with a gluteal pulsating mass underwent exclusion of the persistent sciatic artery including the aneurysm through a retroperitoneal approach with a combination of femorotibial bypass, while the second case with thrombosed persistent sciatic artery only underwent femoropopliteal bypass. To recognize such a rare lesion, awareness of the differential diagnosis is important, and to provide appropriate treatment, an accurate whole image including adequate angiography, a CT scan, and magnetic resonance imaging is necessary.

Aged↗
PubMed1997

The TINS Lecture. The parietal association cortex in depth perception and visual control of hand action.

Recent neurophysiological studies in alert monkeys have revealed that the parietal association cortex plays a crucial role in depth perception and visually guided hand movement. The following five classes of parietal neurons covering various aspects of these functions have been identified: (1) depth-selective visual-fixation (VF) neurons of the inferior parietal lobule (IPL), representing egocentric distance; (2) depth-movement sensitive (DMS) neurons of V5A and the ventral intraparietal (VIP) area representing direction of linear movement in 3-D space; (3) depth-rotation-sensitive (RS) neurons of V5A and the posterior parietal (PP) area representing direction of rotary movement in space; (4) visually responsive manipulation-related neurons (visual-dominant or visual-and-motor type) of the anterior intraparietal (AIP) area, representing 3-D shape or orientation (or both) of objects for manipulation; and (5) axis-orientation-selective (AOS) and surface-orientation-selective (SOS) neurons in the caudal intraparietal sulcus (cIPS) sensitive to binocular disparity and representing the 3-D orientation of the longitudinal axes and flat surfaces, respectively. Some AOS and SOS neurons are selective in both orientation and shape. Thus the dorsal visual pathway is divided into at least two subsystems, V5A, PP and VIP areas for motion vision and V6, LIP and cIPS areas for coding position and 3-D features. The cIPS sends the signals of 3-D features of objects to the AIP area, which is reciprocally connected to the ventral premotor (F5) area and plays an essential role in matching hand orientation and shaping with 3-D objects for manipulation.

Animals↗
PubMed1997

Postoperative posterior retinal holes after pars plana vitrectomy for primary retinal detachment.

BACKGROUND: Although retinal breaks occur frequently during vitrectomy, the postoperative occurrence of new retinal holes close to the vascular arcade after vitrectomy for rhegmatogenous retinal detachment rarely has been reported. METHODS: Three patients with rhegmatogenous, retinal detachment were treated by vitrectomy. More than 49 days after vitrectomy, posterior retinal holes with no retinal detachment occurred halfway between the vascular arcade and the chorioretinal scar around the extrusion hole or the primary retinal tear. RESULTS: These new holes were effectively managed with photocoagulation. CONCLUSION: New hole formation could be caused by the technique of the internal drainage, the contraction of the photocoagulation scar, or epiretinal membrane contraction. Another possibility is that new holes occur through two opposite tangential traction contractile forces: one induced by the contraction of the photocoagulation scar, the other caused by the contraction of the premacular cortical vitreous attached to the vascular arcade.

Aged↗
PubMed1997

[Trend of bacterial meningitis in children over a 14 year period (1981 through 1994) in Japan--an analysis based on studies in 27 institutions].

We observed 266 children with purulent meningitis in 27 institutions in Japan during the 14 years from 1981 on dividing these years into 3 periods, 1981-1985, 1986-1990 and 1991-1994, and studied the trend of causative organisms identified in 254 among the 266 patients. Their ages were less than 3 months after birth in 50 children and 3 months or older in 216: there were 141 boys and 125 girls. The causative organisms were H. influenzae in 134 patients and S. pneumoniae in 50, most of them being aged 3 months or older. Next to the above bacteria ranked S. agalactiae in 29 and E. coli in 12, many of the patients were aged less than 3 months. Staphylococcus spp. was found in 7 patients and about 70% of them were aged 3 months or older. L. monocytogenes was found in 4 patients and N. meningitidis in 3 and they were aged 3 months or older in both patient groups. S. pyogenes, Enterococcus spp., Peptostreptococcus spp., P. Mirabilis and Enterobacter spp. were detected each in 1 patient. The causative organism was unknown in 21 patients and there was no double infection. H. influenzae were detected in 18 patients in 1981-1985 period (36.7%), in 56 in 1986-1990 (54.9%) and in 60 in 1991-1994 (63.8%) showing an increasing tendency, but S. pneumoniae exhibited neither an increasing nor decreasing tendency. There was a decreasing tendency with S. agalactiae and E. coli, but the details were not clear because there were few patients aged less than 3 months. Although the period of coexistence of 4 main bacterial species was not made clear in this study. Listeria is considered to develop mainly in the early childhood, and we believe that the conventional way of using a cephem preparation and ampicillin combined for patients under 6 years need not be altered. However, panipenem (phonetic) is likely to be effective for insensible S. pneumoniae for the time being.

Escherichia coli↗
PubMed1997

[Study of septicemia due to Enterobacter cloacae in a neonatal intensive care unit].

A study was made of Enterobacter cloacae septicemia in 15 newborns in the neonatal intensive care unit (NICU) of the Asahikawa Kosei Hospital from April, 1979 to March, 1996. Their gestational age was 29.7 +/- 4.5 (mean +/- SD) weeks and their birth weight was 1,270 +/- 562 g. The age at the onset of septicemia was 10.3 +/- 7.2 days. Four infants died and the mortality was 26.7%. These infants died within 72 hours after onset of septicemia. Thrombocytopenia (< 50,000/microliter) in the patients who died was significantly more than in the patients who improved (p < 0.05). Antibiotic susceptibilities were determined by the Kirby-Bauer method. Three E. cloacae strains isolated in 1982 were sensitive to ampicillin (ABPC) and cefotaxime (CTX), 4 strains between 1983 and 1984 were resistant to ABPC and were sensitive to CTX, 5 strains between 1985 and 1992 were resistant to ABPC and CTX, and 3 strains between 1993 and 1995 were resistant to ABPC and were sensitive to CTX. These results suggested that the emergence of resistant E. cloacae was related to the use of corresponding antibiotics. Our observations showed that E. cloacae was one of the potential pathogens seen in nosocomial infections which is becoming progressively common in newborns and routine bacteriological surveillance is very important in the NICU.

Bacteremia↗
PubMed1997

[A case of bacterial meningitis induced by strongyloidiasis].

A 75-year-old female with diabetes mellitus, who was born and lived in West north Kyusyu, was admitted to our hospital, because of unconsciousness and loss of appetite. The physical examination showed neck stiffness and a high fever. The laboratory data showed accentuation of inflammatory reaction and azotemia and positive HTLV-1 antibody. The spinal fluid showed increase of cell count and amount of protein. A stool and sputum smear revealed rhabditis form larvae of the nematode. Antibiotics and ivermectin were administered for the bacterial meningitis and hyperinfection of the strongyloides, respectively. Consequently, meningitis and strongyloidiasis improved. It was considered that the patient was infected with strongyloides from her husband who serve in the army during World-War II, and hyperinfection of strongyloides resulted from the immunosuppressive state of diabetes mellitus. Ivermectin, and anti-strongyloides agent, was effective, and no side effects were seen. However, the therapeutic resistance in this case was associated with the positive HTLV-1 antibody.

Aged↗
PubMed1997

Auditory evoked responses under total spinal anesthesia in rats.

In order to investigate the function of the auditory pathway from the cochlea to the brain stem under total spinal anesthesia, the auditory brain stem response (ABR), compound action potential of the cochlear nerve (CAP), and cochlear microphonics (CM) were simultaneously recorded in rats. Total spinal anesthesia was induced by infusion of 2% lidocaine hydrochloride at a constant rate of 0.10 mL/min into the cerebrospinal fluid through the rats' skulls. The ABR completely disappeared within 1.5 to 4 minutes. After cessation of the injection, the ABR reappeared, starting from wave I and progressing through waves II and III to wave IV. The latency change of the CAP throughout the recording period was quite similar to that of wave I of the ABR. A reduction in amplitude of the CM was observed, but the CM did not disappear during the recording period. Disappearance of the ABR was due, not to loss of cochlear function, but to anesthetic effects on the acoustic nerve and the brain stem. Monitoring of the ABR provided information on the level of neural activity in the brain stem under total spinal anesthesia.

Action Potentials↗