Biomedical subjects

T Kumai

Publications and source records attributed to T Kumai.

At least 73 records · Page 4Linked to original sources

PubMed1995

Effects of submaxillariectomy on ovarian androgen and estrogen production in adult female rats.

Submaxillariectomy causes an increase in uterine weight in adult female rats. This increase is due to the elevation of the plasma 17 beta-estradiol (E2) level which is brought on by enhancement of ovarian E2 production. Furthermore, enhancement of ovarian E2 production is due to the enhancement of testosterone and androstenedione production which are the precursors of ovarian E2. However, submaxillariectomy did not affect ovarian progesterone and 17 alpha-hydroxyprogesterone levels. These findings suggest that the submaxillary gland may inhibit the production of ovarian E2 mainly because of the inhibition of ovarian androgen production. Thus the submaxillary gland may play a physiological role in female reproductive systems caused by the change in ovarian steroidogenesis.

17-alpha-Hydroxyprogesterone↗

PubMed1995

Comparative studies on bile flow and biliary lipid excretion after bile-acid loading in normal and partially hepatectomized rats.

This study was performed to investigate sequential changes in bile secretion and biliary lipids after taurocholic acid (TCA) loading of regenerating rat liver. TCA was administered intravenously at stepwise-increasing doses to groups of non-operated control and partially hepatectomized rats, 24, 72 and 168 h after surgery. Bile flow, bile-acid output (BAO) and phospholipid output (PLO) (expressed per gram of liver) in partially hepatectomized rats increased more than in the controls. Using an isolated perfusion rat-liver system, TCA infusion was also carried out on groups of non-operated control and hepatectomized rats 72 h after operation. Again bile flow, BAO and PLO (expressed per gram of liver) were significantly higher in the partial hepatectomy case, mirroring the results obtained in vivo. When horseradish peroxidase (HRP) was pulse-loaded in isolated perfusion preparations, the second peak of biliary HRP secretion in hepatectomized rats was significantly higher than in controls. We conclude that increased bile-acid flow in partially hepatectomized rats is dependent upon acceleration of vesicular transport accompanying or following proliferation in regenerating livers.

Animals↗

PubMed1995

Influence of androgen on tyrosine hydroxylase mRNA in adrenal medulla of spontaneously hypertensive rats.

We investigated the effects of castration and testosterone propionate on tyrosine hydroxylase mRNA, its activity, and catecholamine synthesis in the adrenal medulla of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Four-week-old male rats were castrated. Testosterone propionate (500 micrograms per rat) was administered subcutaneously twice a week to castrated rats (between 14 and 25 weeks of age). Systolic pressure was measured at the age of 25 weeks, and rats were decapitated. The systolic pressure of castrated SHR was significantly lower than that of control and testosterone-replaced SHR. Epinephrine and norepinephrine levels, tyrosine hydroxylase activity, and tyrosine hydroxylase mRNA in the adrenal medulla of castrated SHR were significantly lower than in control and testosterone-replaced SHR. Systolic pressure and epinephrine and norepinephrine levels, tyrosine hydroxylase activity, and tyrosine hydroxylase mRNA levels in the adrenal medulla of WKY showed no significant differences among the control, castrated, and testosterone-replaced groups. These results suggest that androgens contribute to the development and maintenance of hypertension in SHR via sustained enhancement of tyrosine hydroxylase synthesis in the adrenal medulla, leading to increased epinephrine and norepinephrine levels.

Actins↗

PubMed1995

Radiographic analysis of hallux valgus. A two-dimensional coordinate system.

A new method was devised for the evaluation of medial and lateral splaying of the foot on dorsoplantar radiographs made while the patient is bearing weight. This method involves use of a two-dimensional coordinate system; the axis of the shaft of the second metatarsal is the x axis, the intersection of the x axis with the proximal end of the second metatarsal is the point of origin, and the perpendicular to the x axis that passes through the point of origin is the y axis. This method was used to study the radiographs of 177 feet of 112 female patients who had symptomatic hallux valgus and those of ninety-four normal feet of sixty-four female subjects. The site of origin of metatarsus primus varus in the patients who had hallux valgus was the first metatarsocuneiform joint. The great toe and first metatarsal of the patients who had hallux valgus were longer, on the average, than those of the normal subjects. However, the x coordinates at the tip of the great toe and at the end of the first metatarsal were larger only in the patients who were less than twenty years old, because of the progression of angulation of the great toe and of the first metatarsal in the older patients.

Adolescent↗

PubMed1995

Low tibial osteotomy for osteoarthritis of the ankle. Results of a new operation in 18 patients.

Primary osteoarthritis of the ankle with no history of trauma is rare. We report the use of a low tibial osteotomy on 18 ankles in 18 patients, two men and 16 women. The osteotomy is designed to correct the varus tilt and anterior opening of the distal tibial joint surface where it has been shown by weight-bearing radiographs and arthroscopy that there is healthy articular cartilage on the lateral side of the ankle. An opening-wedge osteotomy was used to achieve slight overcorrection. Follow-up of the 18 ankles at an average of 6 years 11 months (2.7 to 12.10) showed the results by our own scoring system to be excellent in six ankles, good in nine, and fair in three with no poor results. Of the three patients with fair results, two had been undercorrected and the third had little residual articular cartilage. Arthroscopic examination of ten ankles showed repair by fibrocartilage in seven. We conclude that slight overcorrection of deformity by low tibial osteotomy is effective in treating intermediate-stage primary osteoarthritis of the ankle.

Activities of Daily Living↗

PubMed1994

The mutant Eisai hyperbilirubinemic rat is resistant to bile acid-induced cholestasis and cytotoxicity.

We investigated bile flow and biliary excretion of bile acids in the Eisai hyperbilirubinemic rat, a Sprague-Dawley mutant rat with conjugated hyperbilirubinemia, using both in vivo and in vitro models. In vivo bile flow was lower in Eisai hyperbilirubinemic rats than in the control rats before and after taurocholate was infused. After taurocholate was infused, bile acid output was similar in the Eisai hyperbilirubinemic rats and control rats. In the isolated perfused rat liver, biliary excretion of bile acids was higher in the Eisai hyperbilirubinemic rats than in the control rats after a high-dose infusion of taurocholate (0.33 mumol/min/gm liver). Infusion of taurochenodeoxycholate (0.22 mumol/min/gm liver) did not produce cholestasis and did not reduce the biliary excretion of bile acids in the Eisai hyperbilirubinemic rats. Taurochenodeoxycholate significantly increased the phospholipid/bile acid molar ratio and slightly reduced bile acid-induced alkaline phosphatase output into bile. The release of lactate dehydrogenase from the perfused liver 30 min after the start of the taurochenodeoxycholate infusion was 10 times lower in the Eisai hyperbilirubinemic rats than in the control rats (2.0 +/- 0.8 vs. 28.7 +/- 6.8 mU/min/gm liver). When the isolated perfused rat liver was infused with a 1-min pulse of horseradish peroxidase (25 mg), we observed an early and late peak of biliary excretion of horseradish peroxidase. The Eisai hyperbilirubinemic rats showed a significant increase in the late peak.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗

PubMed1994

Effects of hysterectomy on ovulation and related ovarian functions in regular estrous cycle rats.

The number of ovulation was significantly higher in hysterectomized rats with regular estrous cycles than in sham-operated rats at the estrous stage 20-24 days after operations (13.2 +/- 0.33 vs. 11.8 +/- 0.41, P < 0.05). This finding suggests that hysterectomy facilitates the follicular maturation in rats. To examine the mechanism of facilitation on follicular maturation in hysterectomized rats, plasma FSH level, ovarian estradiol-17 beta (E2) and ovarian aromatase activity were measured 20 days after hysterectomy. Hysterectomy had no effect on plasma FSH levels at any of the estrous stages. Ovarian E2 level and aromatase activity (AA) were significantly increased by hysterectomy only at diestrus-2 stage of the estrous cycle (E2; 3.76 +/- 0.49 vs. 1.48 +/- 0.49 ng/g ovarian tissue, P < 0.05, AA; 1.36 +/- 0.15 vs. 0.83 +/- 0.11 pmol/h. mg ovarian tissue, P < 0.05), but ovarian testosterone level was not affected by the operation. These results support the hypothesis that in rats hysterectomy facilitates follicular maturation. This may be due to an increase in ovarian E2 level at the diestrus-2 stage, caused by heightened ovarian aromatase activity.

Animals↗

PubMed1994

Role of proprioceptors in the mylohyoid muscle.

Afferent discharges of the mylohyoid muscle branch during respiration were studied electrophysiologically in the rat. Afferent discharges from the mylohyoid muscle branch of the mylohyoid nerve were found to be synchronized with respiration. Stretching of the mylohyoid muscle elicited afferent discharges of the mylohyoid muscle branch, suggesting that lengthening of the mylohyoid muscle caused electrical activity in the proprioceptors. When the central cut end of the mylohyoid muscle branch was stimulated electrically, reflex discharges were recorded from the EMG lead at the sternohyoid muscle where it is innervated by the cervical nerve. The latency between the electrical stimulation and the action potential in the sternohyoid muscle was 3-4 ms. Therefore, the mylohyoid muscle branch may transmit information to the sternohyoid muscle regarding the stretching actions of the mylohyoid muscle resulting from movements of the hyoid bone.

Afferent Pathways↗

PubMed1994

Statistics of differential Lissajous EMG for normal occlusion and Class II malocclusion.

Differential Lissajous electromyography (DL-EMG), a method of representing the simultaneous EMG values of two paired muscles as a single, continuous figure, was used in chewing tests with a sample of Japanese women having normal occlusion compared with a like group of Japanese female adolescents, having Class II, Division 1 malocclusion. For the normal sample, the DL-EMG figures described by the coordinated activity of the bilateral temporal and masseter muscles during chewing gum mastication typically appeared as repetitions of loops. Statistical data were gathered on the total EMG voltages, and on the location, rotational direction, and orientations of the DL-EMG loops when graphed onto Cartesian coordinates. These data were compared with those taken from the Class II sample. Significant differences were observed in the latter group for the EMG voltage levels of the balancing-side masseter muscles. The DL-EMG figures of the Class II group also showed irregularities in the shapes, locations, rotational directions, and orientations of the loops, indicative of irregular masticatory patterns. These data suggest that with sufficient control of factors such as age and sex, electromyography and especially DL-EMG techniques can be useful for characterizing masticatory differences between various occlusal groups.

Adolescent↗

PubMed1994

Elevated tyrosine hydroxylase mRNA levels in the adrenal medulla of spontaneously hypertensive rats.

We investigated the expression of tyrosine hydroxylase (TH) mRNA and its activity in the adrenal medulla of spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). The TH mRNA levels were determined by Northern blot and dot blot analyses. The TH activity and the expression of TH mRNA in the adrenal medulla of SHR were significantly higher than those of WKY (P < 0.01). These results suggested that the hypertension of SHR may be related to the high activity of TH due to the high level of TH mRNA, which increases epinephrine and norepinephrine levels in the adrenal medulla.

Adrenal Medulla↗

PubMed1994

Possible involvement of androgen in increased norepinephrine synthesis in blood vessels of spontaneously hypertensive rats.

We investigated the effects of castration and testosterone propionate on sympathetic nervous systems in spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). Four-week-old male rats were castrated. For replacement of androgen, testosterone propionate (500 micrograms/rat) was administered subcutaneously 2 times a week to castrated rats after their 14th week. The systolic blood pressure of the castrated SHR (44 weeks) was significantly lower than those of intact SHR and testosterone-replaced SHR. The norepinephrine (NE) levels and the tyrosine hydroxylase (TH) activities in the abdominal aorta and mesenteric artery of castrated SHR (45-50 weeks) were significantly lower than those of intact SHR. The NE levels and the TH activities in these blood vessels of testosterone-replaced SHR recovered to the levels obtained in those of intact SHR. As well as the systolic blood pressure, the NE levels and TH activities in blood vessels of WKY were significantly lower than those of intact SHR and showed no significant difference among the three groups. These results suggest that androgen may contribute to the development of hypertension in SHR via sustained enhancement of TH activity in blood vessels leading to increased NE level.

Androgens↗

PubMed1994

Papaverine inhibits bile acid excretion in isolated perfused rat liver.

We investigated the effects of papaverine on bile acid excretion into bile in the presence of infusions of taurocholic acid, tauroursodeoxycholic acid, taurochenodeoxycholic acid and taurodehydrocholic acid in a single-pass, isolated perfused rat liver model. Although continuous infusion of papaverine (1.6 mumol/min) did not reduce bile acid excretion in the presence of low-dose (1.0 mumol/min) infusions of taurocholic acid or tauroursodeoxycholic acid, papaverine significantly inhibited biliary excretion of bile acids in the presence of low-dose taurochenodeoxycholic acid (-50%) and high-dose (3.0 mumol/min) taurocholic acid (-54%), tauroursodeoxycholic acid (-37%) and taurodehydrocholic acid (-31%). During continuous infusion of taurocholic acid (3 mumol/min), a 15-min infusion of papaverine (3.2 mumol/min) reduced bile acid excretion significantly; however, total uptake of bile acid was slightly decreased by the papaverine infusion. Bile acid excretion increased over the baseline value after the papaverine infusion was stopped and then returned to baseline. These results suggest that papaverine does not affect the uptake phase of bile acids at the sinusoidal membrane but may affect the intracellular transport phase or the excretory phase at the bile canalicular membrane. When taurocholic acid was infused at a constant rate of 3 mumol/min for 20 min without papaverine and then stopped, bile acid excretion decreased gradually and was nearly zero by 52 min. Cumulative bile acid excretion in the 52 min after the end of the infusion reached 3.3 +/- 0.2 mumol/gm liver and represented the storage capacity of the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Difference in chewing patterns between involved and opposite sides in patients with unilateral temporomandibular joint and myofascial pain-dysfunction.

Surface electromyograms (EMG) during maximal clenching and gum and peanut chewing were recorded from the temporal and masseter muscles of 30 patients with unilateral temporomandibular joint and myofascial pain-dysfunction (TMD). The gum-chewing integrated EMGs were transformed to a differential Lissajous EMG figure (DL-EMG) to facilitate comparison of mastication on the dysfunctional and opposite side. Variables, mainly those in the gum-chewing DL-EMG, were statistically analysed, and were compared with those of normal subjects. Patients were then classified into three types: (1) same side, (2) opposite side and (3) intermediate side. Same-side patients chewed peanuts on the dysfunctional side, although this side did not necessarily show abnormal behaviour during gum chewing. Opposite-side patients chewed peanuts by avoiding the dysfunctional side and showed excellent chewing activity on the side opposite the dysfunction. Intermediate-side patients had a chewing pattern that was a combination of the first two types. The relation between the pain side, the preferred or habitual mastication side, and the side showing better mastication in the EMG pattern was shown to be important in research on the origin of TMD syndromes. It was speculated that in the same-side patients, overwork on the side with the better dental condition for chewing was the main cause of the dysfunction, and that so-called hyperactivity on the dysfunctional side in TMD patients may result from habitual unilateral mastication.

Adolescent↗

PubMed1993

Masticatory function in a patient with mandibular midline cleft.

Bone grafting of a midline cleft is required to allow reasonable masticatory function. However, changes in the rhythm of mastication have not been investigated before and after such bone grafting procedures. We performed bone grafting in a patient with multiple craniofacial anomalies including a midline mandibular cleft. The patient showed a marked improvement in the rhythm of mastication after repair of the midline mandibular defect. Bone grafting proved to be an effective method for securing stable occlusion with better mandibular movement.

Bone Transplantation↗

PubMed1993

Duodenal stromal tumor with neural differentiation.

A 49-year-old woman was admitted to our hospital for detailed evaluation of an abdominal mass. Ultrasonography and computed tomography revealed two tumors, one a submucosal lesion of the duodenal second portion and the other a left adrenal tumor. Angiography showed that the tumors were hypervascular. Both tumors were removed surgically and examined histologically using hematoxylin-eosin staining. The duodenal tumor (10 x 6 x 5 cm) was initially diagnosed as a schwannoma, but immunohistochemical studies showed that it was S-100 protein negative and neuron-specific enolase positive. Therefore, this tumor was identified as a stromal tumor with neural differentiation. The left adrenal tumor was a nonfunctioning adenoma.

Adenoma↗

PubMed1993

Effects of dibutyryl cyclic AMP and papaverine on intrahepatocytic bile acid transport. Role of vesicle transport.

The secondary messenger cyclic AMP plays an important role in regulating biliary excretory function by stimulating the transcytotic vesicle transport system, whereas papaverine exerts an inhibitory effect on this system. We therefore investigated their effects on bile acid-induced cytotoxicity and intrahepatocytic content of bile acid in primary cultured rat hepatocytes. Simultaneous addition of 1 mM dibutyryl cyclic AMP (DBcAMP), an analogue of cAMP, with 1 mM taurochenodeoxycholic acid (TCDCA) significantly decreased the release of lactate dehydrogenase (LDH) as compared with the case with 1 mM TCDCA alone (7.1 +/- 0.13% of total versus 10.7 +/- 0.3%). In contrast, 0.1 mM papaverine approximately doubled the amount of LDH (22.0 +/- 0.6% of total versus 10.7 +/- 0.3%; P < 0.01). The intracellular content of TCDCA 180 min after the administration of 1 mM TCDCA alone was 20.8 +/- 0.7 nmol/mg protein, that after simultaneous administration of 1 mM DBcAMP, 16.2 +/- 1.0 nmol/mg protein, and that after the simultaneous administration of 0.1 mM papaverine, 38.5 +/- 1.9 nmol/mg protein. A clear correlation between the release of LDH from hepatocytes and the intracellular content of TCDCA was thus observed. When given together with 1 mM taurocholic acid (TCA) or 1 mM tauroursodeoxycholic acid (TUDCA), papaverine exerted little effect on cytotoxicity or intrahepatocytic bile acid content. When cells were bathed in a medium free of bile acid after pretreatment with 1 mM TCDCA and 1 mM DBcAMP, additional exposure to DBcAMP for 30 min significantly stimulated reduction of intracellular TCDCA content (30.2 +/- 0.4% of total versus 44.0 +/- 1.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Tactile-evoked response of sensory fibers in buccal and submandibular regions of the rat.

Evoked neural responses to tactile stimulation were recorded electrophysiologically from the mechanoreceptive afferent fibers innervating the buccal and submandibular regions of Wistar rats anesthetized with sodium thiopental. Miniature probes 200 microns in diameter were used, and data analysis was performed on the mechanosensitivity of responses to tactile stimulation in the areas innervated by the mental, mylohyoid, auriculotemporal, and cervical nerves. Mechano-sensitivity of each area showed a characteristic distribution of slowly adapting (SA), rapidly adapting (RA), C-fiber (CF), and hair follicle (HF) units in individual receptive fields. The density of the SA units was high in the areas innervated by the mylohyoid and auriculotemporal nerves. The CF units were concentrated in the small dome in the area of the mylohyoid nerve and the auriculotemporal nerve, as shown by a significant response to the dynamic features of stimulation. Estimation of the current needed for tactile acuity suggests an important role of the SA fibers in the areas innervated by the auriculotemporal, mylohyoid, and cervical nerves.

Afferent Pathways↗

PubMed1993

[Natural history and URSO dissolution therapy of gallbladder stones in the elderly].

To determine how to treat silent gallstones in the elderly, 1771 autopsied cases 65 years of age or older were studied retrospectively, and 121 cases with asymptomatic gallbladder stones were followed for over 3 years. Of these, 47 cases treated with ursodeoxycholic acid (UDC) for over 3 years were investigated to determine the efficacy of UDC therapy. In the autopsied cases, the incidence of gallbladder stones was 16%, and increased with age. The ratio of males to females was 1:1.2. Only 3.2% of people with silent gallstones developed symptoms. Autopsy studies showed that the majority of people with gallstones died of unrelated causes such as benign respiratory and circulatory diseases. Only 1.8% of patients with gallstones died of acute cholecystitis or gallbladder carcinoma. UDC treatment was effective in 55.9% of patients with radiolucent stones. The percentage of patients requiring surgery due to becoming symptomatic was much lower (6.4%) in UDC-treated patients. The visualization of the gallbladder on cholecystogram improved in cases treated with UDC. These results indicate that elderly patients with silent gallstones generally develop neither symptoms nor carcinoma. Therefore, follow-up management by ultrasonography and cholecystography can be allowed. We also emphasized that a satisfactory response was obtained with long term UDC therapy.

Administration, Oral↗