Biomedical subjects

Y Katoh

Publications and source records attributed to Y Katoh.

At least 181 records · Page 10Linked to original sources

PubMed1989

Water diffusion pathway, swelling pressure, and biomechanical properties of the intervertebral disc during compression load.

The behavior of water in the intervertebral disc of pig tail and its physiologic and biomechanical properties were investigated in relation to compression load. The water content, chemical composition, and swelling pressure in the intervertebral disc were measured, and the mechanism of the generation of the swelling pressure in relation to compression load stress was studied. The swelling pressure, through regulation of the water content of the disc and the resistance of the external load, differs with the region of the intervertebral disc. In the nucleus pulposus and the inner layer of the anulus fibrosus, the swelling pressure rises in proportion to the load, but few changes occur in the outer layer of the anulus fibrosus, and the constant pressure environment is thus maintained. The tritiated water (3H2O) uptake of the disc under various loads was measured. The molar partition coefficient of tritiated water is almost equal to 1 even under a compression load, which suggests that water is freely exchangeable. The diffusion of 3H2O in the intervertebral disc was traced using two pathway models: the perianular route and the end-plate route. The diffusion of water in the unloaded disc for both uptake and washout was about 2 to 3 times larger in the perianular route than in the end-plate route. Under load, the water diffusion was inhibited in both pathways. The relation between the load and displacement revealed viscoelastic properties indicating creep and stress relaxation. Young's modulus and the stiffness increased with a rise in load speed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Multiple-site optical monitoring of neural activity evoked by vagus nerve stimulation in the embryonic chick brain stem.

1. Electrical activity in the embryonic chick brain stem has been monitored optically. The vagus-brain stem preparations isolated from 7-day-old chick embryos were stained with voltage-sensitive merocyanine-rhodanine dyes. 2. Voltage-related optical absorption signals evoked by vagus nerve stimulation with depolarizing and hyperpolarizing pulses using a suction electrode were recorded simultaneously from 127 adjacent loci in the brain stem using a 12 x 12-element photodiode array. 3. The optical signals evoked by the stimulation appeared to be concentrated longitudinally in the central region and in the lateral region, both on the stimulated side of the brain stem, and they did not spread to the opposite side. In addition, the evoked optical responses were detected from small areas on the dorsal surface of the stimulated side, in experiments using transverse slices of brain stem. 4. The optical action potential signals evoked by the brief depolarizing stimulus were conducted slowly and were blocked completely by tetrodotoxin. With relatively long-duration depolarizing and hyperpolarizing stimulations, electrotonic responses were recorded. 5. When 2 microA/2 ms hyperpolarizing pulse stimulations were applied, anode-break excitation signals were detected, and these signals were also blocked by tetrodotoxin. 6. On the basis of the data obtained from these experiments, we constructed maps of the electrical response area and demonstrated the spatial pattern of the vagus dorsal nucleus in the 7-day-old embryonic chick brain stem.

Action Potentials↗

PubMed1989

No specific organ removes atrial natriuretic peptide from the human plasma.

The fate of atrial natriuretic peptide (ANP) was studied by arterial and venous catheterization in ischemic heart disease patients, and arterio-venous blood sampling in healthy kidney donors at the time of transplantation. In vitro ANP degradation was examined using healthy human plasma. In ischemic heart disease, the plasma ANP concentration at the inferior vena cava was 62.6% of that at the left ventricle, and that at the superior vena cava was 82.8%. Arterio-venous gradients were similar from pulmonary artery to vein (88.3%), from celiac artery to the hepatic vein (75.5%) and from the femoral artery to vein (85.4%). In the donor for kidney transplantation, renal arterio-venous gradient was also similar at 77.1%. No platelet consumption of ANP was noted, and the molecular forms of ANP present in the circulation were similar in samples obtained from both the coronary sinus and the superior or inferior vena cava. We conclude that no specific organ plays a dominant role in ANP degradation, and that ANP molecular forms may not be altered during circulation.

Adolescent↗

PubMed1989

[An immune adjuvant activity of mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate, derived from Gordona aurantiaca].

A mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate (GaGM), derived from Gordona aurantiaca, an acid-fast bacterium closely related taxonomically to Mycobacterium, was investigated for its immune adjuvant activity on cell-mediated responses in the mouse. I.V. injection of liposomes containing GaGM enhanced the generation of cytotoxic T-lymphocyte (CTL) against syngeneic and allogeneic tumor cells. In addition, the injection of GaGM augmented the natural killer (NK) activity and the antibody-dependent cellular cytotoxicity (ADCC). These results suggest that the injection of GaGM induces the production of interleukin-2 (IL-2), since such effector cells as CTL, NK and K cells have been shown to require IL-2 for their development.

Adjuvants, Immunologic↗

PubMed1989

[In vitro activation of immune cells by a mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate, derived from Gordona aurantiaca].

A mycolic acid-containing glycolipid, trehalose-2,3,6'-trimycolate (GaGM), derived from Gordona aurantiaca, an acid-fast bacteria closely related taxonomically to Mycobacterium, was investigated for its immune adjuvant activity in vitro. The liposomes containing GaGM showed strong mitogenic effects on murine spleen cells at the doses used (25-100 micrograms/ml), but not on T-cell-depleted spleen cells or macrophage-depleted spleen cells. These results suggest that the mitogenic property of liposomes containing GaGM differs from that of such as lipopolysaccharide, a B-cell mitogen and that its mitogenic effects depend on the presence of macrophages. In addition, liposomes containing GaGM augmented the mixed lymphocyte reaction (MLR) and in vitro induction of cytotoxic T-lymphocytes (CTLs) against allogeneic tumor cells. These results suggest that liposomes containing GaGM have immune adjuvant properties in vitro and the adjuvant activity may be related to such cytokines as interleukin-1 and -2.

Adjuvants, Immunologic↗

PubMed1989

[The effect of the interval from dinner until retiring on the concentration of lithogenic substances during sleep].

The relationship between the interval from dinner until retiring and the concentration of various substances secreted into the urine during sleep was studied in 69 healthy men who had eaten the same meal. The specific gravity and the concentrations of creatinine, uric acid and magnesium in the morning spot urine were highest in subjects who had retired within 2 hours after dinner. The concentrations of calcium and oxalate in the morning spot urine were highest in those who had retired between 2 and 4 hours. The specific gravity and urinary concentrations of creatinine, uric acid and oxalate were markedly higher in those with the interval less than 4 hours than in those 4 hours or longer. The concentrations of calcium, magnesium and citrate were not significantly different between the two groups. From these results, we recommend that the interval from dinner until retiring be prolonged and fluid be drunk before going to bed to decrease the concentration of lithogenic substances during sleep.

Adult↗

PubMed1989

[Influence of dietary animal protein on renal stone disease].

The effect of dietary protein load on the incidence of nephrolithiasis was studied in rats and men. Three groups of adult male Wister rats were fed with a standard protein diet, a high protein diet, or a low protein diet for 4 weeks. In the high protein group, calcium excretion was significantly increased and citrate excretion was remarkably decreased. This group also exhibited low grade metabolic acidosis due to catabolism of excess amino acids, and increases in urinary cyclic AMP excretion and bone resorption. These findings indicate that protein-induced hypercalciuria is due to low grade metabolic acidosis, which directly affects renal handling of calcium. Long-term calcium loss in the urine may lead to negative calcium balance and hyperfunction of the parathyroid gland may induce bone resorption. The influence of 40 g animal protein load on urinary risk factors of calcium stone formation was investigated in 23 healthy males and 26 patients with nephrolithiasis. All subjects were given control diets each day containing 60 g protein for a week and during the next week each received an additional 40 g animal protein. In the controls, added dietary protein resulted in decreased urinary citrate and increased urinary uric acid, with no change in urinary calcium or cyclic AMP excretion. In contrast, the patients showed increased urinary calcium and cyclic AMP as well as decreased urinary citrate. Further examination of the patients revealed that the significant increases of calcium and cyclic AMP excretion occurred only in hypercalciuric patients, who seemed to be classified into renal hypercalciuria.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Study on microleakage and gap observation of composite resin restoration.

The degree of marginal leakage in the cervical cavity restored with Clearfil Bond System F was determined using an autoradiographic technique with 45Ca isotope solution. The isotope used was 0.1 mci/ml of solution in the form of calcium chloride with pH adjusted to 7.0. In addition, the gaps between tooth and restoration were examined by SEM on replicated specimens to evaluate the degree of adaptability. 1. Although there was some degree of difference concerning the leakage between restorative methods, it was found that the leakage in the gingival margin was greater than that of occlusal margin. 2. It was found that the leakage was effectively reduced by etching on the occlusal enamel wall but no effect was observed on the gingival margin. 3. Total etching of the cavity surface was extremely effective in decreasing microleakage of the cavity. Statistically, there was a highly significant difference between the group totally etched and the groups partially etched or not etched at all. 4. The group restored without etching showed a greater increase in leakage after thermal stress was applied. 5. SEM observation suggested that the total etching was significantly effective in improving the bond between tooth surface and restorative materials. 6. The degree of gaps of each portion of the cavity increased in the following order: gingival cementum wall, cavity floor, and gingival dentine wall. No gaps, however, were observed on the occlusal wall. 7. The gaps observed on the cavity floor gradually increased from the occlusal wall to the gingival wall, and the maximum gap was usually observed near the pulpo-gingival line angle. These results indicate that total etching is far more effective in reducing the microleakage.

Acid Etching, Dental↗

PubMed1989

Gap measurement between composite fillings and cavity walls in three different cavities.

Adaptabilities of 8 kinds of resinous restorations on class 5, cervical, and root surface cavities were compared and examined. Human extracted premolars were used as experimental specimens. Restored specimens were divided into two groups: a short storage group stored for 2 weeks and a long storage group for 6 months. After thermal cycling had been undertaken with each group during storage, replicas on vertical section were made to be observed by SEM, the gaps of which were measured on the photographs. These following conclusions were obtained as a result: 1. The appearance and width of gaps between resin and cavity walls were characterized by kinds of cavities. 2. In the class 5 cavity gaps were observed on cavity floor, while almost no gaps were observed in other areas which shows fine adaptability. 3. In the cervical cavity gaps appeared in only cavity floor and on gingival wall. 4. In the root surface cavity the gaps were observed on all cavity walls, whose width was smaller on occlusal wall and especially wider on cavity floor. 5. Clearfil-F and Clearfil-FII showed fine adaptability on all cavities in general, especially on dentinal cavity wall. 6. Isopast without bonding agent and Pile-A as control showed wider gaps than the other adhesive resin. 7. Almost all the materials showed a tendency to form gaps which increased over the passage of time. The difference of width, however, varies depending on the materials; especially stable in Clearfil-F and Clearfil-FII their adhesive power showed no decrease during the experimental period.

Adhesives↗

PubMed1989

[Five cases referred to the First Department of Oral Surgery due to failure of impacted mandibular third molar extraction].

Of patients referred to our department over the post two years due to failure of tooth extraction 5 with impacated mandibular third molars were treated. We found that extraction had been hindered by the narrow operative field due to inadequate incision of the overlying mucosal tissue, insufficient bone resection and inadequate separation of the crown and root.

Humans↗

PubMed1989

Different effect of prostaglandin E2 on B-cell activation by two distinct B-cell differentiation factors, B151-TRF1/IL-5 and B151-TRF2: selective inhibition of B151-TRF2-induced antibody response through increases in intracellular cyclic AMP levels.

Effects of prostaglandin E2 (PGE2) on murine B-cell activation induced by two distinct B-cell differentiation factors, B151-TRF1/IL-5 and B151-TRF2, were examined. A final differentiation of unprimed B cells into IgM-producing cells induced by B151-TRF2 was markedly inhibited by PGE2 at physiological concentrations (around 10(-8) M), whereas B151-TRF1/IL-5- induced antibody responses of unprimed as well as activated B cells were not affected by PGE2, even at 10(-6) M. B-cell responses induced by B151-TRF2-like factors from autoimmune-prone MRL/lpr mice were also inhibited by PGE2. Biphasic increases in intracellular cyclic AMP (cAMP) levels were induced by culturing B cells with 10(-6) or 10(-8) M PGE2: rapid increases within 8 min and delayed increases around 16 hr. The direct addition of dibutyryl cAMP to cultures of B cells resulted in marked inhibition of antibody responses when stimulated with B151-TRF2 but not with B151-TRF1/IL-5. The B151-TRF2-induced antibody responses were also inhibited by cAMP-elevating reagents such as forskolin, cholera toxin and theophylline. Furthermore, 2'.5'-dideoxyadenosine, which is an inhibitor of adenylate cyclase, prevented the PGE2-mediated cAMP accumulation in unprimed B cells as well as the PGE2-mediated inhibition of B151-TRF2-induced B-cell responses when added at the initiation of culture. These results suggest that PGE2 inhibits B151-TRF2-induced antibody responses through the activation of adenylate cyclase and subsequent accumulation of intracellular cAMP, whereas B151-TRF1/IL-5-responsive B cells are resistant to the inhibitory effect of PGE2 and cAMP.

Adjuvants, Immunologic↗

PubMed1989

[The study on the platelet aggregation inhibition activity of placental brush border (the mechanism of platelet aggregation inhibition)].

To clarify the role of placental brush border in the regulation of placental microcirculation, we investigated the platelet aggregation inhibition activity of placental brush border membrane vesicles (BBMV) and obtained the following results. 1. There was very strong platelet aggregation inhibiting activity in placental BBMV. In the 20-40 micrograms/ml protein concentration, the BBMV almost completely inhibited the platelet aggregation induced by ADP, arachidonic acid and collagen, and in the 100-150 micrograms/ml protein concentration, the BBMV almost completely inhibited the platelet aggregation induced by ristocetin. 2. There existed a very strong ADP degrading activity (ADPase activity) in the placental BBMV. The platelet aggregation activity of ADP was completely lost when ADP was preincubated with the placental BBMV. 3. The placental BBMV inhibited platelet malondialdehyde (MDA) production. With the 20 micrograms/ml and 100 micrograms/ml protein concentrations of placental BBMV, 22% and 65% of platelet MDA production was inhibited respectively.

Adenosine Diphosphate↗

PubMed1989

[Dietary habits of Japanese renal stone formers and clinical effects of prophylactic dietary treatment].

The daily consumption of various nutrients and the daily habits of 241 male stone formers were investigated. The patients (especially uric acid stone formers and hypercalciuric (greater than or equal to 300 mg/day) calcium stone formers) ingested much more total protein and animal protein than healthy Japanese. However, the amount of ingested calcium by the patients (470 mg) was less than that of healthy subjects (553 mg) and did not reach the level of the daily nutritive requirement (600 mg). The amount of ingested nutrients during the evening meal by the patients was about 50% of the daily amount with over 60% of the daily animal protein being ingested at dinner. This tendency was high in subjects who were in their 20's to 40's. The interval from dinner until retiring in the patients was not different from that of healthy males, but it was under 4 hours in over 50% of those in their 30's and 40's in both groups. From these results, we thought that a rapid change in nutritional status and dietary style in the short period after World War II had strongly affected the incidence of renal stone disease in Japan. Therefore, we have established the following general guidelines: 1) increased fluid intake, especially after dinner, 2) correct and avoid unbalanced diet (the diet should include all kinds of food, with vegetables being eaten at every meal and avoidance of an excessive intake of meat), 3) eat three meals a day and avoid an excessive intake at dinner, and 4) extend the interval from dinner until retiring. By following these individual dietary guidelines, the 5-year stone recurrence rate and the stone episode rate decreased remarkably in the period of not only outpatient visits but also in the period when the outpatient visits were discontinued. From these results, we conclude that individual dietary management should be the primary measure for the prophylaxis of renal stone disease in Japan.

Adult↗

PubMed1989

[A case of atresia hymen with urinary retention].

A case of atresia hymen with urinary retention was reported. The patient was a 13-year-old female, who visited our clinic complaining of urinary retention and constipation. Examination of the external genitalia revealed atresia hymen . Intravenous pyelography showed hydronephrosis was not present. The symptoms disappeared completely after a hymenal incision was made. This case indicates necessity for caution concerning urological symptoms in females.

Adolescent↗

PubMed1989

[Multiple myeloma in a patient with primary hyperparathyroidism].

A 50-year-old man presented with knee pain and general fatigue and was found to have severe hypercalcemia and renal failure. Hyperparathyroidism was suspected by hypercalcemia and a nodular lesion of the thyroid gland with CT-scan of the patient's neck. Exploration of the neck disclosed two slightly enlarged parathyroid glands. After surgery, the patient's serum calcium levels remained normal for two weeks, but after that his serum calcium levels rose again and renal failure continued. So needle biopsy of the kidney was enforced, and myeloma of the kidney was suspected. Multiple myeloma was diagnosed by bone marrow puncture.

Humans↗

PubMed1989

[An analysis of DNA histogram and the expression of carbohydrate antigens regarding the degree of malignancy in gastric cancer].

We investigated both DNA histogram and the expression of carbohydrate antigens concerning to 168 patients with gastric cancer. Gastric cancer with type II DNA ploidy pattern showed a high incidence of vascular invasion and liver metastasis in the DNA analysis. Furthermore, ten patients with Stage II died of recurrence of gastric cancer within 2 years, of these nine patients showed type II or III DNA ploidy pattern. Then, gastric cancer with type II or III DNA ploidy pattern showed a high incidence of the expression of carbohydrate antigens, where they tended to distribute to cytoplasm and stroma. In conclusion, an analysis of nuclear DNA content appeared useful to predict prognosis in gastric cancer, in which type II DNA ploidy pattern showed the highest degree of malignancy, and both the expression of carbohydrate antigens and their localization possibly fill the role of parameter of the degree of malignancy.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed1989

[A case of right ureteral stricture due to endometriosis in the pouch of Douglas].

A case of right ureteral stricture due to endometriosis in the pouch of Douglas was presented. A 46-year-old housewife was referred to our clinic with asymptomatic macroscopic hematuria on August 22, 1985. Intravenous pyelography (IVP) and abdominal computed tomographic scanning revealed right hydronephrosis and retrograde pyelography showed that ureteral stenosis existed at the lower portion of the right ureter. Right stenotic ureter was removed in 5 cm and ureterovesiconeostomy with psoas hitch method was performed following hysterectomy, left adenexotomy, right salpingectomy on November 28, 1985. Pathological specimen of the ureter revealed that endometriosis existed around the ureteral mucosa. Medication with Danazol was started from the third operative day. Two months later, IVP revealed decreasing right hydronephrosis and she was quite healthy without complaints.

Douglas' Pouch↗

PubMed1988

Atrial natriuretic peptide in human urine.

A highly sensitive radioimmunoassay to measure atrial natriuretic peptide (ANP) concentration in urine has been established, and its clinical usefulness is presented. ANP in urine was stable at 4 degrees C for several days and was easily measured by our radioimmunoassay. The average ANP excretion in 65 healthy persons was 25.0 +/- 1.4 ng/day (mean +/- SEM) and the fractional excretion of ANP was 0.7 +/- 0.05%. In 14 patients with congestive heart failure, the average ANP excretion was 119.2 +/- 29.4 ng/day, which decreased to 53.3 +/- 11.0 after successful treatment.

Adult↗