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Biomedical subjects

T Imai

Publications and source records attributed to T Imai.

At least 217 records · Page 12Linked to original sources
PubMed1999

Cortical asymmetries of the human somatosensory hand representation in right- and left-handers.

Hemispheric asymmetry is known for higher brain functions like language and attention. We tested whether such an asymmetry also exists in the representation of elementary sensory functions. Magnetic source imaging was used to compare the cortical somatosensory hand representation in seven right- and five left-handed individuals. In all right-handers the representation of the dominant hand was larger than the contralateral one in the corresponding hemispheres. In contrast, only two out of five left-handers revealed a larger representation of the dominant left hand compared to the right one. In agreement with previous findings on the lateralization of language and attention, there is a strong correlation between handedness and the extent of the cortical hand representation in right-, but not in left-handers. We conclude that a profound functional hemispheric asymmetry also exists in primary sensory cortices.

Adult↗
PubMed1999

Alteration in amino acids in motor neurons of the spinal cord in amyotrophic lateral sclerosis.

Little is known concerning the changes of amino acid composition in different regions of the spinal cord in patients with amyotrophic lateral sclerosis (ALS). We performed quantitative amino acid analyses in the posterior funiculus, the lateral corticospinal tract, and the anterior horn of cervical enlargement of the spinal cord from seven ALS patients, and the results were compared with those of seven patients with other neurologic diseases (control A) and seven patients without neurologic diseases (control B). The levels of collagen-associated amino acids, hydroxyproline, proline, glycine, and hydroxylysine, were markedly lower in the lateral corticospinal tract and the anterior horn of ALS patients than in controls A and B. The contents of the acidic amino acids glutamate and aspartate were also significantly decreased in the lateral corticospinal tract and the anterior horn of ALS patients as compared with those of controls A and B. These data suggest that decreased contents of collagen-associated amino acids and excitatory amino acids are related to the degeneration of the upper and lower motor neurons in the spinal cord in ALS.

Adult↗
PubMed1999

Vascular response to angiotensin II is exaggerated through an upregulation of AT1 receptor in AT2 knockout mice.

Blood pressure is elevated and pressor response to angiotensin II (Ang II) is exaggerated in AT2 null mice. The purpose of the present study was to elucidate the mechanism for the increased responsiveness to Ang II in the mice. The contraction of aortic strips generated by Ang II was significantly greater in the AT2 gene-deleted mice than the control, which was completely abolished by AT1 antagonist losartan. The aortic content of AT1 receptor was significantly increased (P < 0.05, n = 5) in the AT2 null mice (212 +/- 58.2 fmol/mg protein) compared with the control (98.2 +/- 55.9 fmol/mg protein). While both AT1 and AT2 mRNAs were expressed in the aorta of the control mice, only AT1 mRNA was expressed in the AT2 knockout mice. The expression of AT1 mRNA in the AT2 knockout mice was significantly higher (1.5-fold, P < 0.05, n = 5) than that in the control. The present study clearly demonstrated that the increased vascular reactivity to Ang II in AT2 knockout mice is at least partly due to an increased vascular AT1 receptor expression and suggested that AT2 counteracts AT1-mediated vascular action of Ang II through downregulation of AT1 receptor by a crosstalk between these receptors by some as yet unknown mechanisms.

Aldosterone↗
PubMed1999

Structure, backbone dynamics and interactions with RNA of the C-terminal RNA-binding domain of a mouse neural RNA-binding protein, Musashi1.

Musashi1 is an RNA-binding protein abundantly expressed in the developing mouse central nervous system. Its restricted expression in neural precursor cells suggests that it is involved in the regulation of asymmetric cell division. Musashi1 contains two ribonucleoprotein (RNP)-type RNA-binding domains (RBDs), RBD1 and RBD2. Our previous studies showed that RBD1 alone binds to RNA, while the binding of RBD2 is not detected under the same conditions. Joining of RBD2 to RBD1, however, increases the affinity to greater than that of RBD1 alone, indicating that RBD2 contributes to RNA-binding. We have determined the three-dimensional solution structure of the C-terminal RBD (RBD2) of Musashi1 by NMR. It folds into a compact alpha beta structure comprising a four-stranded antiparallel beta-sheet packed against two alpha-helices, which is characteristic of RNP-type RBDs. Special structural features of RBD2 include a beta-bulge in beta2 and a shallow twist of the beta-sheet. The smaller 1H-15N nuclear Overhauser enhancement values for the residues of loop 3 between beta2 and beta3 suggest that this loop is flexible in the time-scale of nano- to picosecond order. The smaller 15N T2 values for the residues around the border between alpha2 and the following loop (loop 5) suggest this region undergoes conformational exchange in the milli- to microsecond time-scale. Chemical shift perturbation analysis indicated that RBD2 binds to an RNA oligomer obtained by in vitro selection under the conditions for NMR measurements, and thus the nature of the weak RNA-binding of RBD2 was successfully characterized by NMR, which is otherwise difficult to assess. Mainly the residues of the surface composed of the four-stranded beta-sheet, loops and C-terminal region are involved in the interaction. The appearance of side-chain NH proton resonances of arginine residues of loop 3 and imino proton resonances of RNA bases upon complex formation suggests the formation of intermolecular hydrogen bonds. The structural arrangement of the rings of the conserved aromatic residues of beta2 and beta3 is suitable for stacking interaction with RNA bases, known to be one of the major protein-RNA interactions, but a survey of the perturbation data suggested that the stacking interaction is not ideally achieved in the complex, which may be related to the weaker RNA-binding of RBD2.

Amino Acid Sequence↗
PubMed1999

Chemokine PARC gene (SCYA18) generated by fusion of two MIP-1alpha/LD78alpha-like genes.

Two loci in the human genome, chromosomes 4q12-q21 and 17q11.2, contain clusters of CXC and CC chemokine subfamily genes, respectively. Since mice appear to contain fewer chemokine genes than humans, numerous gene duplications might have occurred in each locus of the human genome. Here we describe the genomic organization of the human pulmonary and activation-regulated CC chemokine (PARC), also known as DC-CK1 and AMAC-1. Despite high sequence similarity to a CC chemokine macrophage inflammatory protein-1alpha (MIP-1alpha)/LD78alpha, PARC is chemotactic for lymphocytes and not for monocytes and does not share its receptor with MIP-1alpha. Analyses of the BAC clones containing the human PARC gene indicated that the gene is located most closely to MIP-1alpha (HGMW-approved symbol SCYA3) and MIP-1beta (HGMW-approved symbol SCYA4) on chromosome 17q11.2. Dot-plot comparison suggested that the PARC gene had been generated by fusion of two MIP-1alpha-like genes with deletion and selective usage of exons. Base changes accumulated before and after the fusion might have adapted the gene to a new function. Since there are variably duplicated copies of the MIP-1alpha gene called LD78beta (HGMW-approved symbol SCYA3L) in the vicinity of the MIP-1alpha gene, the locus surrounding the MIP-1alpha gene seems to be a "hot spring" that continuously produces new family genes. This evidence provides a new model, duplication and fusion, of the molecular basis for diversity within a gene family.

Animals↗
PubMed1999

Selective expression of a novel surface molecule by human Th2 cells in vivo.

The search for reliable marker molecules discriminating between human Th1 and Th2 cells identified a gene encoding a novel member of the G protein-coupled leukocyte chemoattractant receptor family, which is selectively expressed in Th2 but not Th1 lineage cells, thereby named CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells). Studies with anti-CRTH2 mAbs demonstrated that CRTH2 was expressed in a small population (0.4-6.5%) of CD4+ T cells in fresh PBMCs of healthy adults, but no remarkable expression was seen in B cells and NK cells. In some cases, CD8+ T cells ( approximately 3.5%) expressed CRTH2. Phenotypes of CD4+ T cells expressing CRTH2 were CD45RA-, CD45RO+, and CD25+, similar to those of Ag-activated effector/memory T cells. Freshly isolated CRTH2+ CD4+ T cells produced Th2- but little or no Th1-type cytokines upon stimulation with PMA and ionomycin. In addition, an allergen-induced proliferative response in fresh PBMCs was significantly and selectively reduced by subtracting CRTH2+ cells. Together, these results indicate that CRTH2 is selectively expressed in vivo in an activated state of Th2 cells including allergen-responsive Th2 cells, suggesting its pivotal roles in ongoing Th2-type immune reactions.

Adult↗
PubMed1999

Characterization of esterases involved in the stereoselective hydrolysis of ester-type prodrugs of propranolol in rat liver and plasma.

An inhibition study showed that the stereoselective hydrolysis of butyryl propranolol (butyryl PL) in rat liver microsomes and plasma involves carboxylesterase. The hydrolysis of (S)-butyryl PL in plasma was specifically inhibited by eserine and bis-nitrophenyl phosphate (BNPP), compared to the (R)-isomer, despite the non-stereoselective hydrolysis of butyryl PL in plasma. In addition, inhibition of hydroloysis by eserine and BNPP showed little stereoselectivity for butyryl PL in liver, although liver microsomes showed an (S)-preferential hydrolysis for butyryl PL (R/S ratio of Vmax/Km: 2.1 +/- 0.2). The hydrolysis of butyryl PL was not inhibited by a polyclonal antibody against a high affinity carboxylesterase (hydrolase A, RH1). Moreover, the high Km value and the high IC50 for phenylmethylsulfonyl fluoride (PMSF) against the hydrolysis of butyryl PL in rat liver microsomes suggest that a low affinity carboxylesterase (perhaps hydrolase B) might be involved in this hydrolysis in rat liver.

Adrenergic beta-Antagonists↗
PubMed1999

Selective expression of liver and activation-regulated chemokine (LARC) in intestinal epithelium in mice and humans.

The liver and activation-regulated chemokine (LARC), also termed MIP-3alpha and Exodus, is a novel human CC chemokine with a selective chemotactic activity for lymphocytes and dendritic cells. Here we describe genomic and cDNA clones encoding the murine orthologue of LARC (mLARC). The gene consists of four exons and three introns. The 5'-noncoding region of about 400 bp contains typical TATA and CAAT boxes but no other potential regulatory elements so far described. The cDNA encodes a CC chemokine of 97 amino acid residues with the highest homology to human LARC (64% amino acid identity). The 3'-noncoding region contains as many as five potential mRNA destabilization signals. mLARC was strongly and transiently induced in the murine monocytoid cell line J774 by lipopolysaccharide (LPS) but not by cytokines such as TNF-alpha, IFN-gamma, IL-1beta or IL-4. In normal mice, mLARC mRNA was expressed selectively in intestinal tissues such as small intestine and colon. Upon treatment with LPS, mLARC expression was enhanced in intestinal tissues and induced in some lymphoid tissues such as lymph nodes. Because of alternative splicing, there are two types of transcripts encoding mLARC and its variant mLARCvar with and without an N-terminal alanine in the mature protein, respectively. Both types of transcripts appeared to be expressed in various mouse tissues. In situ hybridization revealed that epithelial cells of intestinal tissues, especially those lining lymphoid follicles, expressed mLARC. Localization of LARC mRNA in epithelial cells was also demonstrated in a human appendix. Furthermore, mLARC was efficiently chemotactic for cells such as gammadelta type T cells in intestinal epithelium and naive B cells in Peyer's patches. Thus, in both humans and mice, LARC may be physiologically involved in formation and function of the mucosal lymphoid tissues by attracting lymphocytes and dendritic cells toward epithelial cells.

Amino Acid Sequence↗
PubMed1999

Almost pure I(alpha) cellulose in the cell wall of Glaucocystis.

Crystalline features of cellulose microfibrils in the cell walls of Glaucocystis (Glaucophyta) were studied by combined spectroscopy and diffraction techniques, and the results were compared with those of Oocystis (Chlorophyta). Although these algae are grouped into two different classes, by the composition of their chloroplasts for instance, their cell walls are quite similar in size and morphology. The most striking features of their cellulose crystallites are that they have the highest cellulose I(alpha) contents reported to date. In particular, the I(alpha) fraction of cellulose from Glaucocystis was found to be as high as 90% from (13)C NMR analysis. The mode of preferential orientation of cellulose crystallites in their cell walls is also interesting; equatorial 0.53-nm lattice planes were oriented parallel to the cell surface in the case of Glaucocystis, while the 0.62-nm planes were parallel to the Oocystis cell surface. Such a structural variation provides another link to the evolution of cellulose structure, biosynthesis, and its biocrystallization mechanism.

Cell Wall↗
PubMed1999

Successful surgical treatment of a solitary parapharyngeal metastasis from thyroid cancer, using the mandibular swing-transcervical approach: report of a case.

A 72-year-old man presented with a right parapharyngeal mass, 4 cm in diameter, which was subsequently diagnosed as a metastasis originating from papillary carcinoma of the thyroid gland. The parapharyngeal tumor was successfully removed by the mandibular swing-transcervical approach with pharyngeal reconstruction, performed using a buccal mucosal island flap based on the facial artery. His postoperative course was uneventful, and the preoperative clinical symptoms such as dysphagia and headaches completely resolved after surgery.

Aged↗
PubMed1999

Thoracoscopic lung volume reduction surgery for emphysema. Evaluation using ventilation-perfusion scintigraphy.

Thoracoscopic lung volume reduction surgery was conducted in 28 consecutive patients (bilateral 21, unilateral 7). The bilateral procedure was conducted simultaneously in 16 and as a planned staged approach in 5, using stapler resection with Nd:YAG laser ablation. Perfusion and ventilation scintigraphy were used to evaluate status before and after surgery. One operative death (3.6%) due to pneumonia occurred after a simultaneous bilateral procedure. Three to 6 months after surgery, the forced expiratory volume in 1 second (FEV1.0) had improved an average of 44% after the bilateral procedure and 17% after unilateral. Improved ventilation and perfusion distribution in the lower lung field correlated significantly with improved dyspnea scale (p < 0.01). Mean transit time was shortened significantly in each lung field (p < 0.01). Improved mean transit time correlated significantly with improved FEV1.0 and maximum oxygen consumption (VO2max) (p < 0.05). In conclusion, we found that bilateral thoracoscopic lung volume reduction surgery produces short-term functional outcomes superior to those of the unilateral procedure, and should be considered the procedure of choice for most patients. Ventilation and perfusion scintigraphy are useful both in determining target areas for resection and in evaluating lung volume reduction surgery effects.

Aged↗
PubMed1999

Laparoscopic partial adrenalectomy.

BACKGROUND: Most laparoscopic adrenalectomies involve total removal of the whole adrenal gland, and reports of laparoscopic partial adrenalectomies have been very few. The criteria for performing a laparoscopic partial adrenalectomy have not been described. METHODS: (a) Patients with functioning adrenal tumors smaller than 3 cm in diameter were selected. (b) The solitary adrenal tumors were evaluated by preoperative thin-slice computed tomography (CT) scan. (c) Solitary lesions were reconfirmed with intraoperative ultrasonography. (d) Partial adrenalectomy was performed with at least a 5-mm margin using a vascular stapler. RESULTS: Laparoscopic partial adrenalectomy was performed in five patients using the vascular stapler. Hemostasis was perfect in all five patients. The tumor was located in the inferior part of the right adrenal gland in three cases and in the upper pole of the left adrenal gland in two cases. The postoperation pathologic diagnosis was adrenocortical adenoma in all five patients, and excessive hormonal levels or symptoms all disappeared. CONCLUSIONS: Laparoscopic partial adrenalectomy can be performed safely using a vascular stapler.

Adenoma↗
PubMed1999

A case-controlled study of laparoscopic compared with open lateral adrenalectomy.

BACKGROUND: Few studies have been done regarding laparoscopic transperitoneal lateral adrenalectomy compared with open transretroperitoneal lateral adrenalectomy in a case-controlled fashion. METHODS: A case-controlled study of 40 laparoscopic and 40 open adrenalectomies was done in patients who were matched for age, gender, endocrine disorder, side and size of tumor, and area of body surface. Follow-up was complete in 92.5% of the patients, with a mean follow-up period of 30 months. RESULTS: Statistically significant differences (P <0.05) were present (laparoscopic versus open) when the following results were compared: estimated blood loss (40 g versus 172 g), operating time (147 versus 79 minutes), analgesic equivalents (2.9 versus 5.2 times), hospital stay (12 versus 18 days), and late morbidity (0% versus 47.5%). There were no statistically significant differences between the laparoscopic and open groups with regard to time to oral intake, time to walking, intraoperative and early complications, and total cost. CONCLUSIONS: Laparoscopic adrenalectomy is a safe technique that results in greater patient comfort, decrease in estimated blood loss, and earlier discharge than open adrenalectomy, with no increase in cost. It should be adopted as the technique of choice for the removal of functioning adenomas and for adrenal masses less than 6 cm in diameter.

Adenoma↗
PubMed1999

Long-term effects of prostaglandin E2 on the mineralization of a clonal osteoblastic cell line (MC3T3-E1).

Prostaglandin (PG) E2 is thought to be a mediator of the effect of mechanical stress on bone formation, but its effects on osteoblasts have not yet been fully described. Here, the effects of the continuous application of PGE2 and indomethacin, an inhibitor of prostaglandin G/H synthase (cyclo-oxygenase), on the proliferation, differentiation and mineralization of a clonal osteoblastic cell line, MC3T3-E1, were investigated. The cells were cultured in media with either a high (1 microg/ml) or a low (1 ng/ml) concentration of PGE2, with indomethacin (1 microg/ml) and, as a control, with neither agent. The effects of PGE2 and indomethacin were assessed quantitatively. Indomethacin and a high concentration of PGE2 increased the total protein compared to the control and low-PGE2 cultures. 7 days after confluence, alkaline phosphatase (ALP) activity within the cells and extracellular matrices increased. This increase was highest with indomethacin and lowest with a high concentration of PGE2. ALP activity also increased in the medium, but only 21 days after confluence; the effects of the agents were similar to those on the cells and matrices. The accumulation of calcium, inorganic phosphate and hydroxyproline was highest with indomethacin. PGE2 production was at its maximum when the cells were at confluence and was inhibited by indomethacin. Specific [3H]PGE2 binding to the microsomal fraction of the cell was also measured to examine the expression of the PGE2 receptor. The amount of [3H]PGE2 binding per mg of protein was highest at confluence, then decreased and again increased in the mineralizing stage. These results suggest that indomethacin increases ALP activity and the accumulation of mineralized tissue in MC3T3-E1 cells, presumably by inhibiting the production of PGE2. PGE2 could signal the suppression of mineralization as early as confluence.

3T3 Cells↗
PubMed1999

Transcatheter renal arterial embolization therapy on a patient with polycystic kidney disease on hemodialysis.

We report a patient with autosomal dominant polycystic kidney disease (ADPKD) undergoing long-term hemodialysis who underwent transcatheter arterial embolization (TAE) of the renal arteries to shrink enlarged kidneys. In 1983, the patient started hemodialysis because of chronic renal failure secondary to ADPKD. However, renal size continued to increase. In January 1997, he was admitted to our hospital with abdominal distension and anorexia, in addition to progression of anemia. Upper gastroendoscopy showed an esophageal ulcer and severe external compression of the stomach. Renal angiography using the Seldinger technique showed stretched and deformed segmental renal arteries with massive enlargement of the kidneys. TAE with stainless steel coils was performed on both renal arteries. With a rapid and progressive decrease in kidney size, anorexia and anemia were improved, and the gastrointestinal compression was eliminated. In some patients with ADPKD, renal size continues to increase even after the initiation of dialysis. In about 10 years, patients develop gastrointestinal complications, such as dysphagia, ileus, severe constipation, and intestinal perforation. Surgical procedures such as nephrectomy are not satisfactory. This report shows that TAE is a safe and effective therapy for patients with ADPKD with massively enlarged kidneys.

Angiography↗
PubMed1999

A case report of gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation.

We report herein an unusual gastric carcinosarcoma with rhabdomyosarcomatous and neuroendocrinal differentiation in a 63-year-old Japanese male. The tumor was a pedunculated large polypoid tumor (7 x 6.5 x 3.5 cm) located in the pylorus. Histologically, it invaded to the subserosa and was composed of both adenocarcinomatous and sarcomatous components. Adenocarcinomatous foci generally showed tubular to solid patterns and occupied the parts facing the gastric lumen, while the sarcomatous components showed a generally irregular and solid arrangement. There were transitions between the sarcomatous and carcinoma elements. In addition, carcinoma cells with a cord-like or trabecular arrangement similar to that seen in endocrine carcinoma expressed chromogranin A, and were mainly observed in an intermediate area between the adenocarcinomatous and sarcomatous foci. The sarcomatous areas were mainly composed of spindle cells and occasionally contained a sarcomatous component showing rhabdomyosarcomatous differentiation. This is an interesting case to consider how the variety of cell type appeared in such a type of tumor in the stomach.

Biomarkers, Tumor↗