Biomedical subjects

A Chiba

Publications and source records attributed to A Chiba.

At least 55 records · Page 3Linked to original sources

PubMed1999

[Intralobar pulmonary sequestration presenting increased serum CEA, CA 19-9, and CA 125, and associated with asymptomatic pulmonary aspergillosis].

A 44-year-old woman was admitted to our hospital for further evaluation of a consolidated shadow in the left lower lobe and the evaluation of serum tumor markers (CEA 46.3 ng/ml, CA 19-9 1911 U/ml, and CA 125 103 U/ml). Chest computed tomography revealed an irregular shaped, low density mass shadow in the left S10 region, suggesting the diagnosis of pulmonary sequestration or bronchial atresia. However digital subtraction angiography failed to demonstrate an anomalous feeding artery. We could not rule out the possibility that a malignant lesion was included in the consolidated shadow. A left thoracotomy revealed an intralobar pulmonary sequestration of the left lower lobe. Hyphae of aspergillus were found in the lumen of the cystic bronchus of the resected lung. Immunohistochemical studies showed strong expression of CEA, CA 19-9, and CA 125 by bronchial epithelia in the pulmonary sequenstration. The serum values of tumor markers returned to their normal ranges after surgery.

Adult↗

PubMed1999

[In vitro activities of levofloxacin and other antibiotics against fresh clinical isolates].

In this study, the in vitro activity of levofloxacin (LVFX) against 1,020 fresh bacterial clinical isolates was compared with the activities of a range of ofloxacin, ciprofloxacin (CPFX), ampicillin (ABPC), cefaclor, cefpodoxime, methicillin and benzylpenicillin. The clinical isolates except Vibrio cholerae were collected in Japan during 1998 from patients with infectious diseases. MICs were determined using the agar dilution method according to the recommendations by the Japan Society of Chemotherapy. Some isolates of methicillin resistant Staphylococcus aureus (MRSA) and coagulase negative Staphylococcus were resistant to fluoroquinolones, but the MIC50 of LVFX against MRSA was 6.25 micrograms/ml. LVFX was the most active against MRSA among the antibiotics tested. Most of Staphylococcus epidermidis strains were susceptible to the fluoroquinolones. LVFX showed greater activity against all streptococci strains compared with fluoroquinolones tested. In particular, all Streptococcus pneumoniae strains including PRSP were susceptible to LVFX at < or = 1.56 micrograms/ml. Among Enterococcus, ABPC showed superior activity against Enterococcus faecalis but many isolates of Enterococcus species were resistant to ABPC. LVFX was more active against to these Enterococcus species compared with other fluoroquinolones. On the other hand, LVFX and CPFX showed similar activity against isolates of Enterobacteriaceae. CPFX had an MIC50/90 of 0.20, 0.39 microgram/ml and LVFX showed an MIC50/90 of 0.78, 1.56 micrograms/ml against Pseudomonas aeruginosa. LVFX (MIC50/90 0.10, 0.20 microgram/ml) was more active against Acinetobacter species than CPFX (MIC50/90 0.10, 0.39 microgram/ml). Haemophilus influenzae, Branhamella (Moraxella) catarrhalis and V. cholerae were inhibited by low concentration of the fluoroquinolones tested. The MIC90 of LVFX and CPFX were < or = 0.10 microgram/ml against above three species. Some isolates of Neisseria gonorrhoeae and Campylobacter species were moderately resistant to the fluoroquinolones tested but the MIC50 of LVFX and CPFX were < or = 0.39 microgram/ml. Among anaerobes, Propionibacterium acnes was more susceptible than Peptostreptococcus species, and the MIC90 of beta-lactams and fluoroquinolones tested were < or = 0.78 microgram/ml. In conclusion, this study, performed on large number of strains, confirmed an excellent and wide spectrum antibacterial activity of LVFX compared with the fluoroquinolones and beta-lactams tested. And our results suggest that LVFX may be useful in the treatment of various bacterial infections.

Ampicillin↗

PubMed1998

Genetic analysis on the role of integrin during axon guidance in Drosophila.

Heterodimeric cell surface receptor integrin is widely expressed in the nervous system, but its specific role during axon development has not been directly tested in vivo. We show that the Drosophila nervous system expresses low levels of positron-specific (PS) integrin subunits alphaPS1, alphaPS2, and betaPS during embryonic axogenesis. Furthermore, certain subsets of neurons express higher levels of integrin mRNAs than do the rest. Null mutations in either the alphaPS1 or alphaPS2 subunit gene cause widespread axon pathfinding errors that can be rescued by supplying the wild-type integrin subunit to the mutant nervous system. In contrast, misexpressing either the alphaPS1 or alphaPS2 integrin subunit in all neurons leads to no obvious axon pathfinding errors. We propose that integrin does not itself serve as either a "clutch" constituting molecule or a specific growth cone "receptor," as proposed previously, but rather as part of a molecular network that cooperatively guarantees accurate axon guidance.

Animals↗

PubMed1998

Characteristics of muscular contraction caused by magnetic stimulation.

Characteristics of muscular contraction induced by magnetic stimulation were studied using isolated gastrocnemius muscles of a frog. The figure-eight coil position was regarded as 0 degrees when the direction of induced current was parallel to the muscle fiber axis, and 90 degrees when the induced current was perpendicular to the muscle fiber axis. Muscular contraction readily occurred with lower outputs of magnetic stimulation at 0 degrees and 180 degrees, but it was weak at 90 degrees and 270 degrees. Magnetic stimulation did not directly induce muscular contraction but it acted on the synapses forming end plates to muscle cells, and muscular contraction occurred if the direction of the eddy current was parallel to the nerve which innervated the muscle cells.

Animals↗

PubMed1998

Differential regulation of expression of hyaluronan-binding proteoglycans in developing brain: aggrecan, versican, neurocan, and brevican.

We have used a slot-blot radioimmunoassay to quantitate the levels of hyaluronan-binding chondroitin sulfate proteoglycans in developing rat brain from embryonic day 14 (E 14) to eight months postnatal. Recombinant nonhomologous regions of the core proteins were used for immunization to obtain polyclonal antibodies specific for aggrecan, the alpha and beta domains of versican mRNA splice variants, and N- and C-terminal portions of neurocan, while brevican was quantitated using a specific monoclonal antibody. The concentration of aggrecan increased steadily during brain development up to 5 months of age, when it reached a level that was 18-fold higher than at E14. Alternatively spliced versican isoforms containing the alpha domain of the glycosaminoglycan attachment region were present at a relatively low level during the late embryonic and early postnatal period, decreased by approximately 50% between 1 and 2 weeks postnatal, and then increased steadily in concentration to reach a maximum at 100 days that was 7-fold that present at 10 days postnatal. In contrast to these results, versican isoforms containing the beta domain more than doubled in concentration between E14 and birth, after which they decreased by greater than 90% to reach a low "mature" level that remained unchanged between 2 and 8 months. The N- and C-terminal portions of neurocan (produced by a developmentally-regulated proteolytic cleavage in the middle of its chondroitin sulfate attachment region) both increased in embryonic brain during development, reached a peak in the early postnatal period, and then declined thereafter. As in the case of aggrecan, only traces of brevican were detected in embryonic brain and its concentration increased steadily after birth to reach an adult level that was approximately 14-fold higher than that present in neonatal brain. These striking and distinctive changes in the concentrations of the different members of this family of structurally related proteoglycans in developing brain, including changes in opposite directions for versican mRNA splice variants, indicate that the individual proteoglycans and their isoforms probably serve unique functions during nervous tissue histogenesis.

Aggrecans↗

PubMed1998

High affinity binding and overlapping localization of neurocan and phosphacan/protein-tyrosine phosphatase-zeta/beta with tenascin-R, amphoterin, and the heparin-binding growth-associated molecule.

We have studied the interactions of the nervous tissue-specific chondroitin sulfate proteoglycans neurocan and phosphacan with the extracellular matrix protein tenascin-R and two heparin-binding proteins, amphoterin and the heparin-binding growth-associated molecule (HB-GAM), using a radioligand binding assay. Both proteoglycans show saturable, high affinity binding to tenascin-R with apparent dissociation constants in the 2-7 nM range. Binding is reversible, inhibited in the presence of unlabeled proteoglycan, and increased by approximately 60% following chondroitinase treatment of the proteoglycans, indicating that the interactions are mediated via the core (glyco)proteins rather than by the glycosaminoglycan chains, which may in fact partially shield the binding sites. In contrast to their interactions with tenascin-C, in which binding was decreased by approximately 75% in the absence of calcium, binding of phosphacan to tenascin-R was not affected by the absence of divalent cations in the binding buffer, although there was a small but significant decrease in the binding of neurocan. Neurocan and phosphacan are also high affinity ligands of amphoterin and HB-GAM (Kd = 0.3-8 nM), two heparin-binding proteins that are developmentally regulated in brain and functionally involved in neurite outgrowth. The chondroitin sulfate chains on neurocan and phosphacan account for at least 80% of their binding to amphoterin and HB-GAM. The presence of amphoterin also produces a 5-fold increase in phosphacan binding to the neural cell adhesion molecule contactin. Immunocytochemical studies showed an overlapping localization of the proteoglycans and their ligands in the embryonic and postnatal brain, retina, and spinal cord. These studies have therefore revealed differences in the interactions of neurocan and phosphacan with the two major members of the tenascin family of extracellular matrix proteins, and also suggest that chondroitin sulfate proteoglycans play an important role in the binding and/or presentation of differentiation factors in the developing central nervous system.

Animals↗

PubMed1998

"Painting" the target: how local molecular cues define synaptic relationships.

A majority of studies on neuronal growth cones focus on the features that particular groups of neurons share. In contrast, questions such as how specific growth cones respond very differently to the same extrinsic cues require cell-specific experimentation. The most succinct cell-specific growth cone responses occur during synaptic targeting. Recent studies have examined one specific growth cone, the Drosophila RP3 motoneuron growth cone, in variously altered microenvironments. In this review, we summarize how such studies are beginning to uncover the repertoire of extrinsic cues that influence the synaptic targeting of a single growth cone.

Animals↗

PubMed1998

Ontogeny of serotonin-immunoreactive cells in the gut epithelium of the cloudy dogfish, Scyliorhinus torazame, with reference to coexistence of serotonin and neuropeptide Y.

The ontogeny of serotonin (5-HT)-immunoreactive (IR) cells in the gut epithelium of an oviparous elasmobranch, Scyliorhinus torazame, was examined immunohistochemically. 5-HT-IR cells first appeared in the proximal part of the vitellointestinal duct (VID) and in the anterior part of the midgut of the embryo (30 mm in total length). At the 40-mm stage, the cells slightly increased in number and spread to the posterior part of the midgut, but no labeled cells were found in the foregut or hindgut. By the late embryonic (74- and 80-mm) stages, 5-HT-IR cells were markedly increased in number in the spiral intestine and stomach, whereas they were few in the VID and rectum. During these stages, the density of the cells in the inner yolk sac, the derivative of the VID, tended to be increased. This tendency seemed to be consistent in the posthatching juveniles at the 95-mm stage. In juveniles, 125 mm in length and 1.7 months after hatching, the cells further increased in number in the spiral intestine, reaching their adult value. Double immunostaining by the use of anti-5-HT and -neuropeptide Y (NPY) antisera demonstrated that some of the 5-HT-IR cells were also positive for NPY.

Animals↗

PubMed1998

A possible role of the pineal gland in acute immobilization-related suppression of naloxone-induced LH release in ovariectomized estrogen-primed rats.

It has been recently reported that acute immobilization stress almost completely suppresses the luteinizing hormone (LH) release induced by naloxone, a mu-opioid antagonist, in ovariectomized estrogen-primed rats. The present study examined the possible involvement of the pineal gland in the acute immobilization-related suppression of the naloxone-induced LH release. An intraventricular (ICV) injection of 15 microg naloxone produced an abrupt increase in circulating LH concentrations in non-stressed rats. The naloxone-induced LH release was completely eliminated when tested 60 min after the end of a 30 min session of acute immobilization. The same stress conditions did not affect LH-releasing hormone (LHRH)-induced LH release, suggesting that the stress-related suppression of the naloxone-induced LH release was a suprapituitary event. In chronically-pinealectomized rats, but not in sham-pinealectomized rats, naloxone injected 60 min after the end of the stress session evoked a significant increase in serum LH concentrations. However, naloxone injected ICV during the acute immobilization did not elicit LH release in either pinealectomized or sham-operated rats. Under non-stressed conditions, the LH secretory response to naloxone was similar in pinealectomized and sham-operated animals. The same stress (30 min immobilization) significantly increased pineal melatonin content as well as plasma melatonin concentrations in rats bearing intact pineal glands, indicating that stress actually affected the pineal function. These results provide evidence for a role of the pineal in the suppression of the LH response to naloxone after stress, but not during stress.

Animals↗

PubMed1998

Anti-GQ1b ganglioside antibody and ophthalmoplegia of undetermined cause.

BACKGROUND/AIM: Serum antibody against ganglioside GQ1b is reported to be closely associated with immune mediated ophthalmoplegia in the Fisher and Guillain-Barré syndromes. Its presence against glycolipids, in particular ganglioside GQ1b, was investigated in patients with ophthalmoplegia of unknown origin. METHODS: 16 patients with ophthalmoplegia, the cause of which could not be confirmed from clinical findings or diagnostic testing, were tested. 34 patients who had ophthalmoplegia of definite cause, 16 healthy people, and 23 patients with typical Fisher syndrome served as the controls. The ELISA was used to check for serum antibodies against glycolipids in all study participants. RESULTS: Two of the 16 patients with ophthalmoplegia of unknown cause had serum IgG antibody against GQ1b but not against other glycolipids, and 22 of the 23 patients with typical Fisher syndrome had this antibody. No anti-GQ1b antibodies were found in the patients with ophthalmoplegia of definite cause or in the normal controls. CONCLUSION: A common underlying cause appears to bring about the pathogenesis of palsy in Fisher syndrome and in the ophthalmoplegia with positive anti-GQ1b IgG antibody, called atypical Fisher syndrome. This antibody may prove a useful clinical marker for differentiating Fisher syndrome, typical and atypical, in patients with ophthalmoplegia.

Adult↗

PubMed1998

Upper cervical myelopathy associated with low CSF pressure: a complication of ventriculoperitoneal shunt.

A patient who had undergone ventriculoperitoneal shunting developed upper cervical myelopathy. His CSF pressure was markedly low, and deformation of the spinal cord and shrinkage of the subarachnoid space at the upper cervical level were found in radiologic examinations. Ligation of the shunt tube resulted in almost complete recovery. The effect of excessive drainage may have caused the abnormalities.

Cerebral Ventriculography↗

PubMed1998

Commissureless endocytosis is correlated with initiation of neuromuscular synaptogenesis.

We show that the Commissureless (COMM) transmembrane protein is required at neuromuscular synaptogenesis. All muscles in the Drosophila embryo express COMM during the period of motoneuron-muscle interaction. It is endocytosed into muscles before synaptogenesis. In comm loss-of-function mutants, motoneuron growth cones fail to initiate synaptogenesis at target muscles. This stall phenotype is rescued by supplying wild-type COMM to the muscles. Cytoplasmically truncated COMM protein fails to internalize. Expressing this mutant protein in muscles phenocopies the synaptogenesis defects of comm mutants. Thus, synaptogenesis initiation is positively correlated with endocytosis of COMM in postsynaptic muscle cells. We propose that COMM is an essential part of the dynamic cell surface remodeling needed by postsynaptic cells in coordinating synaptogenesis initiation.

Animals↗

PubMed1998

Analysis of nucleotide sequence variations in herpes simplex virus types 1 and 2, and varicella-zoster virus.

To analyze the difference in the degree of divergence between genes from identical herpesvirus species, we examined the nucleotide sequence of genes from the herpes simplex virus type 1 (HSV-1) strains VR-3 and 17 encoding thymidine kinase (TK), deoxyribonuclease (DNase), protein kinase (PK; UL13) and virion-associated host shutoff (vhs) protein (UL41). The frequency of nucleotide substitutions per 1 kb in TK gene was 2.5 to 4.3 times higher than those in the other three genes. To prove that the polymorphism of HSV-1 TK gene is common characteristic of herpesvirus TK genes, we compared the diversity of TK genes among eight HSV-1, six herpes simplex virus type 2 (HSV-2) and seven varicella-zoster virus (VZV) strains. The average frequency of nucleotide substitutions per 1 kb in the TK gene of HSV-1 strains was 4-fold higher than that in the TK gene of HSV-2 strains. The VZV TK gene was highly conserved and only two nucleotide changes were evident in VZV strains. However, the rate of nonsynonymous substitutions in total nucleotide substitutions was similar among the TK genes of the three viruses. This result indicated that the mutational rates differed, but there were no significant differences in selective pressure. We conclude that HSV-1 TK gene is highly diverged and analysis of variations in the gene is a useful approach for understanding the molecular evolution of HSV-1 in a short period.

Amino Acid Sequence↗

PubMed1998

Gastric vascular network in stroke-prone spontaneously hypertensive rats.

The gastric vascular architecture in stroke-prone spontaneously hypertensive rats (SHRSP) was studied three-dimensionally by vascular casting; controls were Wistar Kyoto rats (WKY). The vascular network of the gastric mucosa of WKY showed a cylindrical shape with regular morphology (honeycomb-like capillary network) along the vascular course. In contrast, in SHRSP, an irregular vascular network was formed, and arterioles in the gastric mucosa and serous membrane were difficult to detect. Aneurysms were also detected in some capillaries in SHRSP. We concluded that the development of hypertension may have caused the irregular capillary networks in the rat stomach.

Animals↗

PubMed1998

Changes in the gastric vascular network of malignant stroke-prone spontaneously hypertensive rats (M-SHRSP) after administration of the calcium antagonist manidipine.

In malignant SHRSP (M-SHRSP), a strain of stroke-prone spontaneously hypertensive rat (SHRSP), blood pressure rapidly increases during early development (5 weeks of age). Changes in the gastric vascular architecture of WKY and M-SHRSP were investigated using scanning electron microscope images of vascular casts focusing on the morphological differences in the three-dimensional arrangement of the capillaries. In WKY, the density, tortuosity and regular honeycomb formation of the gastric vessels were studied. The casts of gastric capillaries were 5.9 +/- 0.6 microns in diameter with a regular smooth surface. In M-SHRSP, the overall vascular pattern was not regularly organized at 6.3 +/- 1.9 microns in capillary diameter. Administration of the Ca antagonist, manidipine, to 11-week-old M-SHRSP with hypertensive vascular lesions decreased blood pressure and prolonged the rats' survival. With the administration of manidipine, vascular morphological patterns became similar to that of normotensive WKY, and the mean capillary diameter was 8.4 +/- 1.2 microns. It seems that manidipine plays a role in the recovery of normal vascular structure, as well as decreasing blood pressure.

Animals↗

PubMed1998

Magnetically induced motor evoked potentials and H-reflex during nembutal and ketamine anesthesia administration in rats.

The effects of nembutal and ketamine anesthesia on motor evoked potentials (MEPs) and spinal segment reflex (H-response, F and M waves) were investigated in rats by magnetic stimulation. These potentials were generated by magnetic stimulation of the motor cortex and the spinal cord (L4-L5). After application of nembutal, MEP and H-response decreased in amplitude, eventually disappearing. The amplitudes of F and M waves increased and persisted at the increased levels during anesthesia. The latencies of F and M waves were constant before and after anesthesia. Following ketamine administration, the threshold, latency and amplitude of the magnetically induced MEPs, and M, F and H responses were not influenced systematically. The results suggested that MEPs and H-response depression and/or disappearance due to synaptic site suppression after nembutal anesthesia, and the increase and persistence of increased F and M waves amplitudes were all due to the increasing motoneuron excitability, whereas ketamine did not affect synaptic sites subjected to magnetic stimulation.

Anesthesia↗

PubMed1997

Targeted gene expression without a tissue-specific promoter: creating mosaic embryos using laser-induced single-cell heat shock.

We have developed a method to target gene expression in the Drosophila embryo to a specific cell without having a promoter that directs expression in that particular cell. Using a digitally enhanced imaging system to identify single cells within the living embryo, we apply a heat shock to each cell individually by using a laser microbeam. A 1- to 2-min laser treatment is sufficient to induce a heat-shock response but is not lethal to the heat-shocked cells. Induction of heat shock was measured in a variety of cell types, including neurons and somatic muscles, by the expression of beta-galactosidase from an hsp26-lacZ reporter construct or by expression of a UAS target gene after induction of hsGAL4. We discuss the applicability of this technique to ectopic gene expression studies, lineage tracing, gene inactivation studies, and studies of cells in vitro. Laser heat shock is a versatile technique that can be adapted for use in a variety of research organisms and is useful for any studies in which it is desirable to express a given gene in only a distinct cell or clone of cells, either transiently or constitutively, at a time point of choice.

Animals↗

PubMed1997

A role of dystroglycan in schwannoma cell adhesion to laminin.

Dystroglycan is encoded by a single gene and cleaved into two proteins alpha- and beta-dystroglycan by posttranslational processing. Recently, alpha-dystroglycan was demonstrated to be an extracellular laminin-binding protein anchored to the cell membrane by a transmembrane protein beta-dystroglycan in striated muscle and Schwann cells. However, the biological functions of the dystroglycan-laminin interaction remain obscure, and in particular, it is still unclear if dystroglycan plays a role in cell adhesion. In the present study, we characterized the role of dystroglycan in the adhesion of schwannoma cells to laminin-1. Immunochemical analysis demonstrated that the dystroglycan complex, comprised of alpha- and beta-dystroglycan, was a major laminin-binding protein complex in the surface membrane of rat schwannoma cell line RT4. It also demonstrated the presence of alpha-dystroglycan, but not beta-dystroglycan, in the culture medium, suggesting secretion of alpha-dystroglycan by RT4 cells. RT4 cells cultured on dishes coated with laminin-1 became spindle in shape and adhered to the bottom surface tightly. Monoclonal antibody IIH6 against alpha-dystroglycan was shown previously to inhibit the binding of laminin-1 to alpha-dystroglycan. In the presence of IIH6, but not several other control antibodies in the culture medium, RT4 cells remained round in shape and did not adhere to the bottom surface. The adhesion of RT4 cells to dishes coated with fibronectin was not affected by IIH6. The known inhibitors of the interaction of alpha-dystroglycan with laminin-1, including EDTA, sulfatide, fucoidan, dextran sulfate, heparin, and sialic acid, also perturbed the adhesion of RT4 cells to laminin-1, whereas the reagents which do not inhibit the interaction, including dextran, chondroitin sulfate, dermatan sulfate, and GlcNAc, did not. Altogether, these results support a role for dystroglycan as a major cell adhesion molecule in the surface membrane of RT4 cells.

Animals↗