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Biomedical subjects

K Katoh

Publications and source records attributed to K Katoh.

At least 127 records · Page 7Linked to original sources
PubMed1996

Accuracy verification of a PSD-equipped camera-based photostereometric system developed for measuring cranial movements in six degrees of freedom.

The overall objective of this research is to develop a new type of X-ray television that allows quantitative analysis of jaw movement. Previous X-ray televisions require the patient's head to be held immobile in a normalized orientation by means of a positioning jig. This immobilization, however, is somewhat time consuming and also restricts natural jaw movements. In order to avoid these problems, we have been developing an automatic head-positioning system, consisting of two subsystems: a robotized chair and a head-position sensor. This paper describes the latter sensing subsystem and focuses on its measurement accuracy. To obtain the position and orientation of the head, two video cameras, equipped with a position-sensitive device (PSD), detect the three-dimensional positions of four non-coplanar LED markers mounted on the head. The position data obtained is then utilized to operate the robotized chair so as to hold the head in the same orientation. Accuracy verification study revealed that the overall error of the LED position lay within 1.56 mm (2.8% of total range of the motion. 55 mm) and the spatial resolution at all LEDs was 0.19 mm when using an averaging filter.

Calibration↗
PubMed1996

[Anesthetic management of a patient with erythroderma].

We gave anesthesia to a patient with erythroderma for distal partial gastrectomy. Erythroderma is an inflammatory disorder in which generalized erythema and scaling occur, either as a specific phase of processes such as T cell lymphoma, as a manifestation of underlying malignancy or in the absence of preexisting diseases. Severe cases of erythroderma may involve disturbances in the cardiovascular, thermoregulatory and metabolic systems which make the management of general anesthesia difficult. Systemic scale also causes a difficulty in placing ECG monitor electrodes and endotracheal tube. In the present case, dyspnea and asthmatic bronchitis occurred postoperatively. Therefore, in a patient with erythroderma, we recommend careful systemic management throughout the perioperative period.

Adenocarcinoma↗
PubMed1995

The putative actin-binding role of hydrophobic residues Trp546 and Phe547 in chicken gizzard heavy meromyosin.

In the course of myosin-catalyzed ATP hydrolysis, certain amino acid residues in myosin interact with counterparts in actin to produce the relational changes that underlie muscle contraction; some of these interactions are ionic, but the stronger interactions are hydrophobic. In an effort to identify myosin residues participating in hydrophobic interactions, myosin (from smooth muscle) fragments with mutations at suspected sites were engineered and compared with wild-type fragments. It was found that the ATPase of doubly mutated (Trp546Ser and Phe547His) fragments was minimally activated by actin and did not decorate actin well to form the regular arrowhead pattern characteristic of myosin binding to actin filaments. Thus, we suggest that Trp546 and Phe547 are important participants in the hydrophobic actin-myosin interaction.

Actins↗
PubMed1995

Focal adhesion proteins associated with apical stress fibers of human fibroblasts.

Human fibroblasts stained with fluorescently labeled phalloidin revealed many stress fibers within the apical cytoplasm in addition to those located along the basal plasma membrane and associated with focal adhesions. The staining patterns of these apical stress fibers with fluorescent phalloidin, anti-alpha-actinin, and antimyosin were identical to those of the basal stress fibers, suggesting the same macromolecular organization for both types of stress fibers. There were two types of apical stress fibers that clearly interacted with the apical plasma membrane, those extending between the basal and the apical plasma membrane and those having both ends on the basal membrane forming arches whose top interacted with the apical plasma membrane. By electron microscopy, we observed that apical stress fibers were associated with the apical plasma membrane via electron-dense plaques reminiscent of the focal adhesion. Since several proteins have been specifically localized to the focal adhesion site, we examined whether they were also present at the apical stress fiber-membrane association site by using immunocytochemical methods and image reconstruction techniques. We found that vinculin, talin, paxillin, a fibronectin receptor protein, several integrin subunits including beta 1, fibronectin, and proteins with phosphorylated tyrosine were also components of the apical plaque. These observations indicate that apical stress fibers are attached to the plasma membrane by using principally the same molecular assembly as the focal adhesion associated with the basal stress fiber. We suggest that the complex molecular organization of the focal adhesion is not demanded by cell adhesion, but rather it is needed for anchoring stress fibers to the plasma membrane. Apical plaques did not stain with the anti-integrin alpha v subunit or anti-focal adhesion associated kinase (FAK), although these antibodies stained focal adhesions. These results suggest that the apical stress fiber-membrane contact has some important functions different from those of the focal adhesion.

Antibody Specificity↗
PubMed1995

Synthetic peptides demonstrate RGD-independent platelet glycoprotein IIb/IIIa recognition site in cell binding domain of human fibronectin.

Fibronectin binds to platelet membrane glycoprotein (GP) IIb/IIIa in both an Arg-Gly-Asp (RGD)-dependent and -independent manner. The identification of an RGD-independent binding domain(s) that interacts with GPIIb/IIIa may be the key to understand the mechanism of thrombus formation. A recombinant fibronectin fragment containing the residues from Ile1359 to Ser1436 (lacking the RGD sequence) had been shown to bind to GPIIb/IIIa in a divalent cation- and activation-dependent manner. To identify a minimal peptide ligand that participates in the recognition of GPIIb/IIIa, we synthesized peptides extending this region, which consist of 12 amino acid residues in length and overlapping by six amino acids. We obtained evidence that two 12-residue peptide sequences from this region (residues 1371-1382 and 1377-1388) inhibit fibronectin binding to GPIIb/IIIa by interacting directly with this receptor, with IC50s of 95 +/- 16 and 104 +/- 19 microM, respectively. These peptides inhibited the binding of fibrinogen to GPIIb/IIIa, as well as ADP-induced platelet aggregation. These results indicate that an RGD-independent GPIIb/IIIa binding site in the cell binding domain of fibronectin was localized within the residues His1377-Ile1382.

Adenosine Diphosphate↗
PubMed1995

Case report: inhalation therapy of paromomycin is effective for respiratory infection and hypoxia by cryptosporidium with AIDS.

A 24-year-old man with AIDS and hemophilia A had intractable diarrhea and fever. Upon examination of stool and of a sigmoidal biopsy specimen, cryptosporidium was revealed. Approximately 2 months after admission, respiratory infection with hypoxia due to cryptosporidium developed. Paromomycin inhalation was effective therapy. To the authors' knowledge, this is the first case of respiratory cryptosporidiosis treated successfully by paromomycin inhalation.

AIDS-Related Opportunistic Infections↗
PubMed1995

Role of transforming growth factor beta 1 on hepatic regeneration and apoptosis in liver diseases.

AIMS: To investigate the effects of transforming growth factor beta 1 (TGF-beta 1) on regeneration and induction of apoptosis of liver cell and bile duct in various liver diseases. METHODS: Formalin fixed paraffin wax sections of 18 liver tissue samples were obtained by needle biopsy, surgery, or necropsy; these included six liver cirrhosis, three obstructive jaundice; five fulminant hepatitis, one subacute hepatitis, and three normal liver. Expression of TGF-beta 1, apoptosis related Le(y) antigen, Fas antigen, a receptor for tumour necrosis factor, and biotin nick end labelling with terminal deoxynucleotidyl transferase mediated dUTP (TUNEL) for locating DNA fragmentation, was investigated histochemically. RESULTS: TGF-beta 1 was expressed in areas of atypical bile duct proliferation, where bile duct continuously proliferated from liver cells. In occlusive jaundice and fulminant hepatitis, TUNEL was positive in nuclei and cytoplasm of metaplastic cells which formed incomplete bile ducts, and these cells appeared to extend from TGF-beta 1 expressing liver cells. Fas antigen was found only on the cell membrane of proliferated bile duct in fulminant hepatitis, which differed from TGF-beta 1 and TUNEL positive areas. Le(y) antigen was expressed in liver cell and bile duct at the areas with atypical bile duct proliferation, but its coexpression with TUNEL was rare. CONCLUSIONS: TGF-beta 1 plays a role in the arrest of liver cell regeneration and atypical bile duct proliferation, and in areas of rapidly progressing atypical bile duct proliferation, such as in fulminant hepatitis or bile retention. Apoptosis appears to be induced by TGF-beta 1. This phenomenon may account for the inadequate hepatic regeneration that occurs with liver disease.

Apoptosis↗
PubMed1995

[A review of studies of the delayed neurotoxicity induced by organophosphorus esters].

Organophosphorus esters have been used in the plastics industry as antioxidants and plasticizers, in agriculture as insecticides, and in the military as nerve agents. Some of these compounds have organophosphorus ester-induced delayed neurotoxicity (OPIDN) different from the acute toxicity caused by the acetylcholine esterase inhibiting activity. this review describes recent progress in studies on OPIDN and, discusses the future direction of studies. OPIDN is characterized by a more than 7 day incubation period, lower limb paralysis accompanied by axonal degeneration, and age- and species-specificity. Younger animals and rodents are not very sensitive to OPIDN. As well as fast recovery of inhibited neurotoxic esterase or neuropathy target esterase (NTE) in the sciatic nerve, detoxicating mechanisms including carboxylesterases are contributing to age- and species-specificity for OPIDN. Although, anterograde axonal transport does not seem to be affected by OPIDN, slow down of retrograde axonal transport was observed. Inhibition of NTE, and aging of inhibited NTE has been thought to be responsible for OPIDN, but there are some arguments against the role of NTE in OPIDN. Phosphorylation of cytoskeletal proteins by kinases such as calcium dependent-calmodulin kinase II and/or high affinity neurotoxic compound binding site(s) are possible candidates for the initiation of OPIDN. Triphenyl phophite (TPP), a compound commonly used in the plastics industry, has delayed neurotoxicity that is somewhat different from OPIDN. The onset of TPP-induced neuropathy is earlier than that of OPIDN, and rodents are sensitive to TPP. In addition to the axonal damage, cell damage is observed in TPP-induced neuropathy. Mitochondrial energy metabolism-related enzymes could be the target of this neuropathy. Future studies should be focused on the relation of OPIDN to the phosphorylation of cytoskeletal proteins and high affinity binding site(s), and on the development of rodent models. These studies would answer the questions related to OPIDN, and further contribute toward elucidating the pathogenesis of degenerative neuronal diseases.

Aging↗
PubMed1995

Biliary metabolites of semotiadil fumarate in the rat.

After oral administration of 14C-semotiadil fumarate to rat, 81.3% of the dosed radioactivity was excreted into the bile. Five major biliary metabolites were detected and characterized as phenolic O-glucuronides by FAB mass spectrometry and 1H-nmr spectrometry. From these results it was concluded that the first step in the metabolism of semotiadil in rat was oxidations at various portions around the molecule to produce phenols. These oxidations implied the ring-opening of the methylenedioxy ring, O-demethylation of the methoxybenzene, hydroxylation of the ring, and aromatic N-demethylation. The next step was O-glucuronidation of the resulting intermediate phenolic metabolites.

Animals↗
PubMed1995

The immunosuppressant FK506 increases the rate of axonal regeneration in rat sciatic nerve.

The axonal regenerative properties of the new immunosuppressant drug FK506 (tacrolimus) are further explored in this continuing study. In an initial report (Gold et al., 1994a), we described the ability of FK506 to reduce the time until return of function in the hind feet of rats following a sciatic nerve crush. In the present study, we examined the morphological correlate underlying this enhancement of functional recovery. In rats receiving daily subcutaneous injections of FK506 (1.0 mg/kg) for 18 d following a sciatic nerve crush the regenerating axons appeared larger in size compared to saline-injected control animals. Morphometric analysis of axonal calibers in the soleus nerve demonstrated that mean axonal areas for the largest 30% of axons were increased over axotomized control values by 93% in the FK506-treated animals. Next, the rate of axonal regeneration was determined by radiolabeling the L5 dorsal root ganglion (DRG) at 9 and 14 d following axotomy. Regression analysis of the outgrowth distances for sensory axons between 10 and 15 d revealed a 16% increase in regeneration rate. Electron microscopy of intramuscular nerve branches in the interosseus muscles confirmed that the axons in the FK506-treated animals were further advanced toward their targets; in some instances, axons were shown to reinnervate muscle spindles. The results are discussed in terms of the known ability of FK506 to inhibit the activity protein phosphatase 2B (calcineurin).

Animals↗
PubMed1995

[A case report: postoperative recurrence of peritoneal dissemination of gastric cancer responding to sequential methotrexate and 5-FU (5-fluorouracil)].

In a 61-year-old female patient, the recurrence of peritoneal dissemination after total gastrectomy due to gastric cancer responded well to chemotherapy of sequential methotrexate and 5-FU. A total of 10 courses of this chemotherapy diminished ascites, normalized the value of CA 19-9, and re-opened the left obstructed ureter. During this therapy, the patient's condition was good, with no experience of nausea or leukopenia.

Adenocarcinoma↗
PubMed1995

Relationship between the therapeutic effects or side-effects and the serum disopyramide or mono-N-dealkylated disopyramide concentration after repeated oral administration of disopyramide to arrhythmic patients.

After we had developed a method to determine simultaneously the blood concentrations of disopyramide (DP) and its metabolite mono-N-dealkylated disopyramide (MND) by high-performance liquid chromatography, DP was administered repeatedly to arrhythmic patients in order to examine the relationship between the serum DP or MND concentration and the therapeutic effects or side-effects. To 79 arrhythmic patients (57 patients with ventricular premature contraction, 13 with supraventricular arrhythmia and 9 with atrial fibrillation), DP was administered repeatedly at an initial oral dose of 200 to 400 mg/day. Of the 61 patients which were possible to evaluate after reaching a steady state, 32 were evaluated as effective and 29 as non-effective, the effective rate being 52.5%; the mean blood DP concentration (+/- S.D.) was 2.14 +/- 0.65 and 1.74 +/- 0.62 micrograms/ml, respectively, with a significant difference between the two groups (p +/- 0.05). At the final dose, 40 patients were evaluated as effective and 18 as non-effective, the effective rate being 69.0%; the mean blood DP concentration was 2.03 +/- 0.67 and 2.09 +/- 0.68 micrograms/ml, respectively, with no significant difference between the two groups. Among 42 patients with premature contraction, 26 were evaluated as effective and 16 as non-effective, the effective rate being 62%; the mean blood DP concentration was 2.01 +/- 0.62 and 2.20 +/- 0.70 micrograms/ml respectively, with no significant difference between the two groups. The incidence of side-effects was 17.7%, and there were no significant differences in blood DP or MND concentrations between the groups with and without side-effects. A blood DP concentration more than 2 micrograms/ml may be required to achieve the therapeutic effect of DP administered repeatedly.

Adult↗
PubMed1994

Immunohistochemical demonstration of embryonic expression of an odor receptor protein and its zonal distribution in the rat olfactory epithelium.

Using an antibody raised against an odor receptor protein, we investigated immunohistochemically the spatial distribution in the embryonic and adult rat olfactory epithelium of the olfactory receptor neurons that express the odor receptor protein. In adults, the immunoreactive olfactory receptor neurons were intermingled with immuno-negative receptor neurons, but were mostly restricted within a circumferential zone located in the lateral part of the epithelium. The immunoreactive olfactory receptor neurons were observed as early as embryonic day 14, with a strong tendency to localize in the lateral part of the epithelium. These results indicate that both selection of the odor receptor protein by individual olfactory receptor neurons and zonal segregation of the odor receptor protein expression occur early in embryonic development of the olfactory system.

Animals↗
PubMed1994

Development of glomerular structure in rabbit olfactory bulb: three-dimensional reconstruction under the confocal laser scanning microscopy.

Confocal laser scanning imaging was used to reconstruct the three-dimensional distribution of the aggregates of olfactory receptor axons terminating within individual glomeruli in the rabbit main olfactory bulb. Two monoclonal antibodies, R2D5 and R4B12, were used to mark selectively the olfactory receptor axons. Thick coronal sections (100-200 microns in thickness) through the bulb were labeled with either of the antibodies, and then serial optical sectioning was performed to reconstruct three-dimensional optic images of the labeled axons in the glomeruli. The results revealed an intricate internal structure of the glomeruli with a mesh-like arrangement of bundles of terminal olfactory axons. Developmental study showed that primitive glomeruli lacking the internal structure of the adult form first appear in the 22-day embryo and that the characteristic internal structure of the glomeruli develops mainly during postnatal days. The confocal laser scanning image method together with specific molecular markers provides a simple tool for the three-dimensional analysis of the glomerular structure.

Age Factors↗
PubMed1994

Calcium regulating hormones and bone mineral content in patients after subtotal gastrectomy.

Twenty-nine men who had undergone Billroth I gastrectomy and 19 men who had undergone Billroth II gastrectomy were studied to examine the changes in their calcium regulating hormones and bone mineral content following surgery. The serum calcium and phosphate concentrations in the patients with Billroth I and Billroth II were normal. The Billroth II group had an elevated level of serum alkaline phosphatase and reduced bone mineral content. The 24,25(OH)2D concentration was reduced (P < 0.01) and 25(OH)D and 1,25(OH)2D concentrations were increased (P < 0.01, P < 0.05, respectively) in the Billroth II group. It was suggested by our study that the Billroth II patients had a reduced bone mineral content and an elevated 1,25(OH)2D concentration. Therefore, the pathophysiology of postgastrectomy bone metabolic disease is not due to vitamin D deficiency, but may instead be due to reduced calcium absorption in the intestine.

Aged↗
PubMed1994

Direct evidence for erythropoietin-induced release of endothelin from peripheral vascular tissue.

The effect of recombinant human erythropoietin (r-HuEPO, 0.1 to 2.0 U/ml) on endothelin-1 (ET-1) release was examined in isolated hind legs perfused with Krebs-Ringer solution from normal rats. r-HuEPO increased immunoreactive (ir-) ET-1 release in a dose-dependent fashion; the maximal percent increment in ir-ET-1 release evoked by r-HuEPO (2.0 U/ml) was about +210% over the basal rate of release. However, r-HuEPO showed no effect on release of angiotensin II, thromboxane B2 or vasodilatory prostaglandin I2 from the vasculature. These results not only provide direct evidence that r-HuEPO has the potential to specifically stimulate release of ET-1 from peripheral vascular beds, but, hence, suggest a contributory role of ET-1 in r-HuEPO-induced hypertension in anemic human subjects undergoing r-HuEPO therapy.

6-Ketoprostaglandin F1 alpha↗