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Biomedical subjects

K Homma

Publications and source records attributed to K Homma.

At least 37 records · Page 2Linked to original sources
PubMed2001

Apolipoprotein-E phenotype and basal activity of low-density lipoprotein receptor are independent of changes in plasma lipoprotein subfractions after cholesterol ingestion in Japanese subjects.

We investigated whether the apolipoprotein-E (apoE) phenotype and the basal activity of low-density lipoprotein (LDL) receptor, which were reported to be the major determinants for increase in plasma LDL levels by cholesterol ingestion, have the same role in Japanese subjects whose diet is low in fat and cholesterol. Cholesterol (750 mg/d) was added to the ordinary diet as a dried egg-yolk supplement for 4 wk to 110 subjects. Plasma levels of lipids, apolipoproteins, and cholesterol in lipoprotein subfractions were measured at the beginning and end of the test period. Phenotyping of apoE was determined by an isoelectric focusing-immunoblotting method, and LDL receptor activity in lymphocytes was determined by flow cytometry. Plasma levels of cholesterol in less-dense LDL (LDL(1)) and less-dense high-density lipoprotein (HDL(2)) were slightly but significantly increased, 3.4% and 4.1%, respectively, by cholesterol ingestion, but the increases were not statistically significant in any of E2, E3, and E4 groups. The distribution of the apoE phenotype was equivalent in all three LDL-cholesterol groups (no change, increase, and decrease by cholesterol ingestion). Plasma levels of LDL, LDL(1), and LDL(2) cholesterol were not significantly increased in the three groups of subjects with lymphocyte LDL-receptor activities (low, medium, and high). As with apoE phenotype, LDL-receptor activities were the same in all three LDL-cholesterol groups. In addition, there were no significant correlations between LDL-receptor activity and changes in plasma levels of lipids, apolipoproteins, and cholesterol in lipoprotein subfractions. Therefore, we concluded that cholesterol ingestion significantly increases plasma levels of less-dense LDL and HDL, but neither apoE phenotype nor basal LDL-receptor activity explain the variability in changes in plasma lipoprotein subfractions by cholesterol ingestion in Japanese subjects.

Apolipoproteins E↗
PubMed2001

Three-dimensional helical CT of the breast: accuracy for measuring extent of breast cancer candidates for breast conserving surgery.

OBJECTIVE: To evaluate the accuracy of three-dimensional (3D) helical computed tomography (CT) for assessing the extent of breast cancer of candidates for breast conserving surgery. METHODS: Results of helical CT were studied in 144 lesions of 144 patients with breast cancer before breast-conserving surgery. A lesion was defined as positive if focal enhancement was detected by CT within 100 s after contrast material administration. After resection, tumors were histopathologically mapped and correlated with the extent of 3D images. RESULTS: Helical CT enabled detection of 143 tumors but not of one ductal carcinoma in situ (DCIS). The median deviation of the tumor extension revealed by 3D helical CT images from pathological assessment was 7.7 mm (range 0-60 mm). The extent of tumors was significantly correlated with CT measurements (r = 0.714, p < 0.0001). By multivariate analysis, the presence of invasive tumors with intraductal extensions beyond the edge of the invasive tumor and histologic type (DCIS) were significant risk factors for deviation of the tumor extension revealed by 3D helical CT images from pathological assessment. CONCLUSION: Three dimensional helical CT of the breast is an accurate preoperative imaging modality for assessing the extent of breast cancer candidates for breast conserving surgery.

Adult↗
PubMed2001

Non-optical tip-sample distance control method for scanning near-field optical microscopy using a piezoresistive micro cantilever.

A piezoresistive micro cantilever is applied to monitor the displacement of an optical fibre probe and to control tip-sample distance. The piezoresistive cantilever was originally made for a self-sensitive atomic force microscopy (AFM) probe and has dimensions of 400 microm length, 50 microm width and 5 microm thickness with a resistive strain sensor at the bottom of the cantilever. We attach the piezoresistive cantilever tip to the upper side of a vibrating bent optical fibre probe and monitor the resistance change amplitude of the strain sensor caused by the optical fibre displacement. By using this resistance change to control the tip-sample distance, the two-cantilever system successfully provides topographic and near-field optical images of standard samples in a scanning near-field optical microscopy (SNOM)/AFM system. A resonant characteristic of the two-cantilever system is also simulated using a mechanical model, and the results of simulation correspond to the experimental results of resonance characteristics.

Journal Article↗
PubMed2001

Color Doppler sonography in monitoring after free jejunum transplantation.

The authors assessed the usefulness of color Doppler imaging in the monitoring of vascular circulation after free jejunum transplantation. Seven male patients were examined daily with color Doppler sonography for the first postoperative week between 1999 and 2000. All sonographic examinations were performed with an SSD5500 ultrasound scanner. Arterial and venous signals were documented reliably in all patients. The flashing red spots around the serosal wall revealed the patency of the anastomosed artery and vein. No failures of the graft occurred. The presence of the color Doppler signals was considered sufficient to define vascular patency. The real-time monographic (B-mode) examination revealed the thickness and the plicae circulares of the jejunum wall. These monographic (B-mode) images supported the viability of the transplanted jejuna. The authors found color Doppler sonography to be a reliable and effective form of monitoring after free jejunum transplantation.

Esophagus↗
PubMed2001

Treatment of ischial pressure ulcers with a posteromedial thigh fasciocutaneous flap.

This study describes the use of the posteromedial thigh fasciocutaneous flap for the treatment of ischial pressure sores. The authors prefer this flap because it is the fasciocutaneous flap nearest to the ischial region, it is easy to raise, and it causes no donor-site morbidity. In this study, 11 ischial pressure sores in 10 paraplegic patients were closed using the posteromedial thigh fasciocutaneous flaps. All flaps survived, although two caused distal necrosis; after these same two flaps were readvanced, they survived. After an average follow-up time of 77 months, seven of the 10 patients have had no recurrence of ulcers. This fasciocutaneous flap was previously described by Wang et al. However, this study revealed that the arrangement of the vascular pedicle was different from that described by Wang et al. To reveal the vascular supply of this flap, anatomic dissections were conducted. The source of circulation to this flap was the suprafascial vascular plexus, in addition to the musculocutaneous perforator. The dominant pedicle was the musculocutaneous perforator from either the adductor magnus muscle or the gracilis muscle. The key to safe elevation of this flap was the accurate outlining of the skin island directly over the vascular pedicle and the preservation of the proximal fascial continuity. Of the 11 flaps, two viability problems occurred. These partial flap losses resulted from the failure to properly include the perforator. It is the authors' conclusion that the width of the flap should be greater than 5 cm. In addition, it is safe to make a flap within a 1:3 base-to-length ratio in a fatty, diabetic patient. This posteromedial thigh fasciocutaneous flap was found to be a valuable alternative for reconstruction of primary or recurrent ischial pressure ulcers.

Adult↗
PubMed2001

In vitro high-resolution helical CT of small axillary lymph nodes in patients with breast cancer: correlation of CT and histology.

OBJECTIVE: This study seeks to determine whether high-resolution in vitro helical CT can show the internal structure of small axillary nodes and to establish the CT characteristics of benign versus metastatic axillary nodes in patients with breast cancer. SUBJECTS AND METHODS: We obtained in vitro helical CT images of 212 nodes excised from 19 patients with breast cancer. The longest mean size was 5.9 mm, and the range was 0.5 to 26.5 mm. The hilar and cortical characteristics, the size, and the ratio of the longest axis to the shortest axis were evaluated. CT findings were correlated with histologic findings. RESULTS: Pathologic assessment of excised nodes with a central low-density hilum visualized on CT showed arteries, veins, lymphatic sinuses, and fatty tissue. A peripheral high-density cortex on CT contained mostly lymphatic tissue. Abnormal (eccentric, irregular) cortices were observed in malignant nodes (p<0.0001). Marked differences were observed among the proportions of benign and malignant nodes when the ratio of the longest axis to the shortest axis was less than 2 and an abnormal cortex was observed. CT could also detect extracapsular lymph node extension. CONCLUSION: In vitro high-resolution helical CT can detect the internal structure of small nodes. Morphologic changes detected on helical CT help distinguish benign from malignant nodes.

Adult↗
PubMed2000

Ca(2+)-dependent regulation of the motor activity of myosin V.

Mouse myosin V constructs were produced that consisted of the myosin motor domain plus either one IQ motif (M5IQ1), two IQ motifs (M5IQ2), a complete set of six IQ motifs (SHM5), or the complete IQ motifs plus the coiled-coil domain (thus permitting formation of a double-headed structure, DHM5) and expressed in Sf9 cells. The actin-activated ATPase activity of all constructs except M5IQ1 was inhibited above pCa 5, but this inhibition was completely reversed by addition of exogenous calmodulin. At the same Ca(2+) concentration, 2 mol of calmodulin from SHM5 and DHM5 or 1 mol of calmodulin from M5IQ2 were dissociated, suggesting that the inhibition of the ATPase activity is due to dissociation of calmodulin from the heavy chain. However, the motility activity of DHM5 and M5IQ2 was completely inhibited at pCa 6, where no dissociation of calmodulin was detected. Inhibition of the motility activity was not reversed by the addition of exogenous calmodulin. These results indicate that inhibition of the motility is due to conformational changes of calmodulin upon the Ca(2+) binding to the high affinity site but is not due to dissociation of calmodulin from the heavy chain.

Actins↗
PubMed2000

Immunosuppressive effect on T cell activation by interleukin- 16-cDNA-transfected human squamous cell line.

It is well known that it is difficult to induce an immunotolerance with allogeneic skin transplantation. We attempted to find the immunosuppressive protocol for prolonging skin allograft rejection by using interleukin-16 because IL-16 is considered one of the natural ligands to CD4 molecules. First we examined whether synergistic immunosuppressive effects of recombinant IL-16 plus anti-CD4 mAbs are induced in mixed lymphocyte reaction (MLR). Next we used IL-16-cDNA-transfected OSC-20 (human oral squamous cell carcinoma cell line) as an in vitro model of the epidermal keratinocyte equivalent and examined whether this transfectant could inhibit the activation of allogeneic T cells. Our data indicated that IL-16 clearly inhibited human MLR and that IL-16 increased synergistically the immunosuppressive effect of anti-CD4 mAb. We also used IL-16 transfectant and this produced more than 50 ng/ml of IL-16 in the supernatant by which human MLR was significantly inhibited. Furthermore, this transfectant also inhibited the activation of allogeneic lymphocytes stimulated directly with transfectant cells. These results indicated that the IL-16-producing allogeneic skin graft might have a local immunosuppressive action that would prolong graft survival.

Antibodies, Monoclonal↗
PubMed2000

Urinary steroid profile in adrenocortical tumors.

Determination of the urinary steroid profile has been proposed as a sensitive tool for diagnosing adrenocortical tumors. The urinary steroid profiles were determined for patients with adrenocortical tumors. Urinary steroids were extracted, derivatized to form methyloxime-trimethylsilyl ether and analyzed by gas chromatography/mass spectrometry. Patients with adrenal adenomas from primary hyperaldosteronism had increased metabolites of 18-hydroxycorticosterone and aldosterone, and those with Cushing's syndrome had elevated excretion of 11 -deoxycortisol, cortisol, 18-hydroxycortisol, and cortisone metabolites. In patients with adrenocortical carcinomas, increased levels of metabolites of 11-deoxycortisol or 33-hydroxy-5-ene steroids were observed. The urinary steroid profiles of adrenal adenomas and adrenocortical carcinomas were quite different, suggesting the diagnostic validity for discriminating malignant from benign diseases.

Adenoma↗
PubMed2000

Technique for selective microangiography of skin flaps with high contrast and fine detail.

The technical factors of microangiography were studied, and the authors found that the main limiting factors in resolution were the injection pressure of the contrast medium and the thickness of the materials. A gentle manual hand pressure injection, with the aid of visual monitoring under the operating microscope, were keys to obtaining beautiful microangiograms.

Angiography↗
PubMed2000

Evidence for recycling of cytochrome P450 sterol 14-demethylase from the cis-Golgi compartment to the endoplasmic reticulum (ER) upon saturation of the ER-retention mechanism.

Cytochrome P450 sterol 14-demethylase (P450-CYP51) is the enzyme that catalyzes 14alpha demethylation of lanosterol, a step in ergosterol biosynthesis, on the cytoplasmic side of the endoplasmic reticulum (ER) in Saccharomyces cerevisiae. To investigate its localization and the localization mechanism(s), we constructed a chimera by inserting a 30-residue segment, Leu(283)-Leu(312) of P450-CYP51 containing a potential N-glycosylation site in the cytoplasmic region, into the N-terminus of the same protein and tagging the C-terminus with three repeats of a hemagglutinin epitope. This chimera complements gene disruption on a single-copy vector and undergoes N-glycosylation, showing that it functions normally in vivo. Indirect immunofluorescence microscopy revealed that this chimera is localized exclusively to the ER when it is expressed on either a single-copy or multicopy vector. We carried out pulse-chase experiments and found that this chimera, when expressed on a multicopy plasmid, gradually undergoes alpha1-->6 glycosylation, a cis-Golgi-specific modification, but not alpha1-->;3 glycosylation, a medial Golgi-specific modification. In contrast, a single-copy expression of this chimera does not lead to the cis-Golgi-specific modification. These findings suggest that, when expressed on a multicopy plasmid, a fraction of this chimera is transported from the ER to the cis-Golgi compartment and subsequently recycled to the ER, but when expressed on a single-copy plasmid, no significant transport of this protein from the ER takes place. We thus suggest the possibility that cytochrome P450 is retained in the ER by a saturable static mechanism.

Aspartic Acid Endopeptidases↗
PubMed2000

Solution structure of myosin-ADP-MgFn ternary complex by fluorescent probes and small-angle synchrotron X-ray scattering.

In the presence of excess amounts of fluorine, a physiological divalent cation, magnesium (Mg(2+)), forms a novel phosphate analogue, magnesium fluoride (MgFn). Park et al. [Biochim. Biophys. Acta 1430, 127-140 (1999)] previously demonstrated that MgADP. MgFn forms a complex with myosin subfragment-1 (S-1), and the S-1.ADP. MgFn ternary complex mimics a transient state in the activity cycle of ATPase. In the present study, localized conformations in the regions of highly reactive cysteine and lysine residues, Cys 707 (SH1), Cys 697 (SH2), and Lys 83 (RLR), which change their conformations markedly during ATP hydrolysis, were studied using fluorescent probes and chemical modification. The global shape of the complex was also studied using small angle X-ray solution scattering and compared it with other previously reported myosin.ADP. fluorometal ternary complexes. The results suggest that the overall conformation and localized functional regions of the complex are quite similar to those in the presence of ATP, indicating that the complex mimics the M(**).ADP.P(i) steady state.

Adenosine Diphosphate↗
PubMed2000

Conformational changes in the unique loops bordering the ATP binding cleft of skeletal muscle myosin mediate energy transduction.

Myosin has three highly-conserved, unique loops [B (320-327), M (677-689), and N (127-136)] at the entrance of the ATP binding cleft, and we previously showed that the effects of actin are mediated by a conformational change in loop M [Maruta and Homma (1998) J. Biochem. 124, 528-533]. In the present study, loops M and N were photolabeled respectively with fluorescent probes Mant-8-N(3)-ADP and Mant-2-N(3)-ADP in order to study conformational changes in the loops related to energy transduction. The effect of actin on the conformation of loop N was examined by analyzing fluorescence polarization and acrylamide quenching; the results were then compared with those previously reported for loop M. In contrast to loop M, the fluorescence polarization and the value of K(sv) of the Mant-groups crosslinked to loop N were slightly affected by actin binding. To study conformational changes in loops M and N during the ATPase cycle, FRET was analyzed using TNP-ADP.BeFn and TNP-ADP. AlF(4)(-) as FRET acceptors of Mant fluorescence. The resultant estimated distances between loop M and the active site differed for the Mant-S1.TNP-ADP.BeFn and Mant-S1.TNP-ADP.AlF(4)(-) complexes, whereas the distances between loop N and the active site differed slightly. These findings indicate that the conformation of loop M changes during the ATPase cycle, suggesting that Loop M acts as a signal transducer mediating communication between the ATP- and actin-binding sites. Loop N, by contrast, is not significantly flexible.

Acrylamide↗
PubMed2000

Anaerobic orbital abscess/cellulitis in a Yorkshire Terrier dog.

A retrobulbar abscess/cellulitis occurred in a Yorkshire Terrier dog. The clinical signs were exophthalmos, prolapsed nictitating membrane and purulent ocular discharge. Ultrasonography showed a marked soft tissue swelling of the retrobulbar tissues as well as echogenic parallel lines between the globe and the medial orbital rim. Surgical exploration of the orbit was performed and no foreign body was found. The pterygopalatine fossa was incised and therapeutic retrobulbar drainage attempted. A drain was placed to encourage ventral drainage of the abscess. Anaerobic cultures revealed heavy growth of gram negative rods (prevotella bivia and prevotella buccae were isolated). Recovery was successful but subsequent treatment for keratoconjunctivitis sicca was necessary. A full recovery of tear production occurred after several weeks.

Abscess↗
PubMed2000

[Correlation between prior coronary revascularization and perioperative cardiac events in patients for noncardiac surgery].

We evaluated the influence of interval between prior coronary revascularization and subsequent noncardiac surgery on perioperative cardiac events. We retrospectively identified 162 consecutive patients with previous revascularization procedures who had undergone noncardiac surgery. Postoperative cardiac complications occurred in 10 (6.2%) patients, cardiac death in 1 patient, and significant arrhythmia in 3 patients. These patients had higher rates of unstable angina, myocardial infarction within 3 months, cerebrovascular disease, peripheral vascular disease, renal dysfunction (Cr > or = 1.9 mg.dl-1) and higher preoperative risk scores as described by the Cleveland Clinic (P < 0.05). Also, the incidence of cardiac complications increased when noncardiac surgery was performed within 1 week of previous percutaneous transluminal coronary angioplasty (PTCA) and in more than 5 years after coronary artery bypass grafting or PTCA (P < 0.05). Although PTCA is widely accepted, especially in Japan, early lesion progression was observed during the first several days and atherosclerotic progression was apparent in more than 5 years after the procedure. Therefore, the time between coronary revascularization and noncardiac surgery, as well as atherosclerotic risk factors, is important in evaluating patients with history of previous revascularization procedures.

Aged↗
PubMed1999

An 86 kDa diapause protein 1-like protein is a component of early-staged encapsulation-relating proteins in coleopteran insect, Tenebrio molitor larvae.

Recently, we reported two novel early-staged encapsulation-relating proteins (56 kDa and 48 kDa ERPs) isolated from the hemolymph of coleopteran insect, Tenebrio molitor larvae [Cho et al. (1999) Eur. J. Biochem. (in press)]. Here, a cDNA clone for another early-staged encapsulation-relating protein (86 kDa) was isolated. We found that the 86 kDa protein shows high homology with insect diapause protein 1. The 86 kDa protein was localized in the fat body and hemolymph, but not hemocyte lysate. A significant level of 86 kDa protein was detected in pre-pupae stage, but it decreased rapidly at late larvae and pupae, and no protein was found in embryo, early larvae and adult stages. This diapause protein 1-like protein is likely to be a component of early-staged encapsulation-relating proteins in the insect cellular defense reaction.

Amino Acid Sequence↗
PubMed1999

The pro-phenoloxidase of coleopteran insect, Tenebrio molitor, larvae was activated during cell clump/cell adhesion of insect cellular defense reactions.

To characterize the proteins involved in cell clump/cell adhesion of insect cellular defense reactions, we induced the cell clump/cell adhesion reaction in vitro with the hemolymph of larvae of the coleopteran insect, Tenebrio molitor. The 72 kDa protein was specifically enriched in the residues of cell clump/cell adhesion and was purified to homogeneity. A cDNA clone for the 72 kDa protein was isolated. We found that the 72 kDa protein was an activated phenoloxidase from Tenebrio pro-phenoloxidase. We suggest that activated phenoloxidase is involved in the cell clump/cell adhesion reaction as well as in the synthesis of melanin.

Amino Acid Sequence↗