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T Shiga

Publications and source records attributed to T Shiga.

At least 55 records · Page 3Linked to original sources
PubMed2000

Experimental use of a transportable hyperbaric chamber durable for 15 psi at 3700 meters above sea level.

A transportable hyperbaric chamber durable for 15 psi of pressure was used to treat a patient suffering from moderate acute mountain sickness at 3700 m above sea level. The symptoms were ameliorated a few minutes after pressurization in the chamber. After a 20-minute stay in the chamber, the patient was completely free of symptoms. Since the chamber can be inflated by using compressed air from a cylinder, no strenuous work was required of the operators. This transportable chamber seems to be useful for the treatment of high-altitude disorders at around 3000 m above sea level.

Acute Disease↗
PubMed1999

Dynamic computed tomography predicts tumor temperature and response to thermoradiotherapy in superficial and subsurface tumors.

BACKGROUND: Dynamic computed tomography (CT) was performed on patients undergoing thermoradiotherapy for superficial or subsurface tumors, and the correlation between tumor enhancement and tumor temperature during hyperthermia was evaluated. The authors further investigated whether tumor enhancement by dynamic CT is predictive of tumor response to thermoradiotherapy. METHODS: Thermoradiotherapy was given to 26 patients. Radiotherapy consisted of 40-70 gray. Hyperthermia was conducted over 3-5 sessions, and tumor temperature was measured at each session. Dynamic CT was performed prehyperthermia (within 1 week before the initiation of hyperthermia) and midtherapy (within 1 week after 2 sessions of hyperthermia). RESULTS: A complete response (CR) was obtained in 11 patients (42%) and either a partial response or no response (non-CR) in 15 (58%). There was no correlation between tumor enhancement obtained by prehyperthermia CT and tumor temperature parameters or response. However, the deltaCTmax (maximum increased enhancement) by prehyperthermia and midtherapy CT was 39.0 +/- 18.9 HU and 26.1 +/- 14.2 HU, respectively, in CR patients, and 46.4 +/- 21.1 HU and 49.6 +/- 19.1 HU, respectively, in non-CR patients. This change in deltaCTmax at midtherapy was significantly different between groups (P < 0.01). The deltaCTmax ratio for prehyperthermia and midtherapy CT studies correlated with the average tumor temperature (P < 0.05). CONCLUSIONS: Tumor enhancement by prehyperthermia and midtherapy dynamic CT predicted tumor temperature during hyperthermia and response to thermoradiotherapy for superficial or subsurface malignancies.

Adult↗
PubMed1999

Close spatial-temporal relationship between islet-1-expressing cells and growing primary afferent axons in the dorsal spinal cord of chick embryo.

The relationship between the appearance of Islet-1-expressing cells and the longitudinal growth of primary afferent axons (PAAs) in the dorsal spinal cord of chick embryos was examined. Islet-1-expressing cells first appeared in the dorsal spinal cord at embryonic days (E) 3-3.5. These immunoreactive cells were aligned in a longitudinal column in close proximity to longitudinally elongating PAAs in the presumptive dorsal funiculus. By E8, when many PAAs invade the spinal gray matter, Islet-1-expressing cells had disappeared in the dorsal spinal cord. Following the dorsoventral rotation of the spinal cord in ovo before the invasion of PAAs, a close topographical relationship between Islet-1-expressing cells and PAAs was maintained. These results suggest that Islet-1-expressing cells may play a role in the longitudinal growth of PAAs in the dorsal funiculus.

Animals↗
PubMed1999

Hyperventilation after tourniquet deflation prevents an increase in cerebral blood flow velocity.

PURPOSE: In this study we examined whether normocapnia maintained by hyperventilation after lower limb tourniquet deflation prevents an increase in cerebral blood flow velocity. METHODS: Thirteen patients, undergoing elective orthopedic surgery, requiring a pneumatic tourniquet around the lower extremity, were divided into two groups. In group 1, ventilation was controlled at tidal volume of 10 mL x kg(-1) and respiratory rate of eight per minute after tourniquet release. In group 2, ventilation was controlled to maintain P(ET)CO2 between 30 and 35 mmHg after tourniquet release. Arterial blood pressure, heart rate, peak and mean middle cerebral artery (MCA) flow velocity, and arterial blood gas were measured every minute for ten minutes after tourniquet release. The MCA blood flow velocity was measured using Transcranial Doppler ultrasonography (TCD). RESULTS: In group 1, the maximum peak MCA flow velocity was 53+/-6 cm x sec(-1) (50%+/-6% increase compared with pre- release value), and achieved 3+/-0.4 min after tourniquet release. In group 2, there was no increase either in mean or peak MCA velocity after tourniquet release. CONCLUSIONS: Normocapnia maintained by hyperventilation after tourniquet deflation prevents an increase in cerebral blood flow velocity.

Blood Flow Velocity↗
PubMed1999

Validity of 99mTc-DMSA renal uptake by planar posterior-view method in children.

Renal uptake of 99mTc-DMSA has been quantified by various methods. The aim of this study is to obtain a normal value for 99mTc-DMSA renal uptake calculated by the posterior view method and age variation, and to assess its clinical validity. Scintigrams of 238 children (0-12 years) with 99mTc-DMSA were reviewed. All the children had a clinical history of primary vesicoureteral reflux and/or neurogenic bladder, ureteral or urethral anomalies. Their kidneys were divided into two groups, "normal" and "abnormal" according to their scintigraphic findings and split renal functions. Percent renal uptake per injected dose (% RU) was quantitated from planar images at 2 hours after injection of an age-adjusted dose (26-95 MBq) of 99mTc-DMSA. Calculated total % RU, individual % RU of the right and left kidneys (mean +/- sd) in patients with normal kidneys were 40.7 +/- 5.0%, 20.2 +/- 3.0%, 20.4 +/- 2.7%, respectively. There was no significant correlation between % RU and age (r = 0.231). Longitudinal variation in the % RU in 9 patients ranged from 1.2% to 18%. Our conventional method for quantifyng % RU is simple, practical and feasible in routine clinical practice, especially for children under follow up.

Adolescent↗
PubMed1999

Administration time-dependent effect of nitrendipine on the reduction of cardiac hypertrophy in spontaneously hypertensive rats.

The influence of administration time of nitrendipine on the regression of cardiac mass was studied in spontaneously hypertensive rats (SHR). Nitrendipine (100 mg/kg) was given once daily at 10 AM or 10 PM for 16 weeks. Similar reductions of the trough blood pressure were observed in both groups. Cardiac biventricular mass in the animals dosed at 10 PM was significantly less than that in the vehicle-treated rats, whereas in the rats dosed at 10 AM no significant reduction was noted in the cardiac mass. These data suggest that the administration time of nitrendipine has a different effect on the regression of cardiac hypertrophy in SHR.

Animals↗
PubMed1999

Osteoporosis influences the late period of fracture healing in a rat model prepared by ovariectomy and low calcium diet.

To elucidate the influence of osteoporosis on the fracture healing, we produced a rat osteoporosis model by ovariectomy and by maintaining a low calcium diet; and monitored the healing process radiographically, histologically, and biomechanically for 12 weeks. Radiologic, histologic and biomechanical findings of the fracture areas 6 weeks after making the fractures were almost identical in both the osteoporosis group and the control group. However, 12 weeks after making the fractures, newly generated bones in the osteoporosis group showed histological osteoporotic changes and their bone mineral density on the fracture site decreased. These findings show that estrogen-deficient and low calcium conditions greatly affect the bone in the later period of the healing process, but do not affect remarkably the early healing period. This is clinically important when we consider fracture treatments for patients with osteoporosis due to menopause.

Animals↗
PubMed1999

Hypoxia potentiates ultraviolet A-induced riboflavin cytotoxicity.

Flavins are thought to be important chromophores for chronic photo-induced skin injury, but the mechanism is not well known. We have reported that the primary cytotoxicity remaining in ultraviolet A-irradiated riboflavin solution is attributable to hydrogen peroxide. Because the dermis is more hypoxic than the atmosphere, we investigated the cytotoxicity of riboflavin solution during and after ultraviolet A irradiation under hypoxia. Riboflavin solution showed stronger cytotoxicity during irradiation under hypoxia than under air. Riboflavin solution that had been irradiated under hypoxia at lower ultraviolet A doses showed stronger cytotoxicity and contained more hydrogen peroxide than solution irradiated under air at the same doses. At higher ultraviolet A doses, however, the cytotoxicity and hydrogen peroxide quantity were similar in riboflavin solutions irradiated under different oxygen conditions. The effect of a singlet oxygen quencher, sodium azide, on the induction of cytotoxicity and production of hydrogen peroxide by ultraviolet A irradiation of riboflavin solution was examined. The presence of sodium azide in the solution during ultraviolet A irradiation suppressed the cytotoxicity and hydrogen peroxide production to similar levels at various ultraviolet A doses regardless of oxygen conditions. At the maximum suppression by sodium azide, hydrogen peroxide production decreased to 10% of the unsuppressed production. About 40% of the oxygen molecules of hydrogen peroxide produced was thought to be derived from oxygen dissolved in the riboflavin solution.

Cell Line↗
PubMed1999

Clinical characteristics of amiodarone-induced thyrotoxicosis and hypothyroidism in Japan.

Since amiodarone was introduced in Japan in 1992, the incidence of the drug-induced thyroid dysfunction has been increasing. We studied the thyroid function of 13 patients with amiodarone-induced thyrotoxicosis (AIT) and 11 patients with amiodarone-associated hypothyroidism (AAH) who had been referred to our Institute in the last 6 years. AIT and AAH developed after 39+/-21 and 20+/-16 months of amiodarone treatment, respectively. One patient developed AAH followed by AIT. The AIT ranged from subclinical to overt thyrotoxicosis. Four patients with moderate to marked AIT were treated with methimazole. Their thyrotoxicosis persisted for 3 to 9 months, despite administration of antithyroid agents. One patient with mild thyrotoxicosis was treated with prednisolone, resulting in a euthyroid state in a few months. Eight patients with asymptomatic to moderate thyrotoxicosis resolved spontaneously without any treatment. In four asymptomatic patients with AIT, serum levels of T3 and T4 were in the upper normal range or slightly high (< 12 microg/dl), accompanied by suppressed TSH (<0.1 microU/ml) and high thyroglobulin levels, suggesting destruction-induced thyrotoxicosis. Such a subclinical thyrotoxicosis developed repeatedly in one patient. Ultrasonographic studies revealed no nodular lesion in the thyroid, and color flow Doppler sonography demonstrated no hypervascularity in the thyroid gland in any AIT patient. Although it is postulated in Europe that there are two types of AIT, namely type I, which develops in patients with latent Graves' disease or toxic multinodular goiter, and type II, which develops in an apparently normal thyroid as destructive thyroiditis, all AIT patients we have seen so far had developed destructive type AIT. Sufficient intake of iodide and a very low incidence of toxic multinodular goiter may account for the rare incidence of type I AIT in our country. Mild to moderate AIT resolved spontaneously without discontinuing amiodarone, but it was discontinued in two of 13 AIT patients because of extrathyroidal adverse reactions.

Adult↗
PubMed1999

Relationship among 201T1 uptake, nuclear DNA content and clinical behavior in metastatic thyroid carcinoma.

UNLABELLED: A prospective study of 201TI uptake was performed to compare 201TI uptake with nuclear deoxyribonucleic acid (DNA) content and clinical behavior of tumors in metastatic thyroid carcinoma and to assess the significance of 201TI uptake in evaluating clinical characteristics of thyroid carcinoma. METHODS: Fifty-six patients with metastases of differentiated thyroid carcinoma had 201TI scintigraphy. Grade of 201TI uptake was semiquantitatively assessed according to tumor-to-background ratio on 2-h late scan. Nuclear DNA content was analyzed within 3 wk of 201TI study by flow cytometry using biopsy material and was classified as diploidy or aneuploidy. Patients were followed up to examine incidence of tumor growth and/or anaplastic transformation. RESULTS: DNA content was diploidy in 48 patients and aneuploidy in 8 patients. 201TI uptake in the DNA-aneuploid group (2.61 +/- 0.29) was significantly higher than that in the DNA-diploid group (1.82 +/- 0.35, P < 0.01 for both groups). Tumor growth was observed in all patients with DNA aneuploidy but in only 5 of 48 patients with DNA diploidy (P < 0.01). Anaplastic transformation was observed in 3 patients in the DNA-aneuploid group but in none of the patients in the DNA-diploid group. CONCLUSION: High 201TI uptake indicates greater incidence of abnormal DNA content with aggressive clinical behavior of metastatic tumors. Thus, 201TI scintigraphy may be useful in characterizing metastatic thyroid carcinoma and in identifying those patients with poorer prognoses.

Adenocarcinoma, Follicular↗
PubMed1999

[Visualization of normal organs in whole-body FDG-PET imaging].

It is important to know FDG accumulation in the normal distributions for interpreting whole-body PET imaging for tumor detection. Twenty-eight normal subjects were studied with whole-body PET imaging and were examined the intensity of FDG uptake in major organs and the factors which caused it's variety. Emission images were acquired and images were reconstructed without attenuation correction. The intensity of FDG uptake was classified into 4 grades visually. No accumulation was found in the thyroid, the esophagus and the spleen. The oral cavity, the liver, the stomach, and the colon were visualized in all subjects. The laryngeal muscle, the cervical muscle, and the heart accumulated FDG with various grade from 1 to 4 grades. No association was found between the intensity of uptake in the organs and volunteer's age. The fasting time was shorter in volunteers whose heart showed "high" grade than those showed less accumulation (p < 0.05). Serum concentration of free fatty acid was significantly lower in them, too (p < 0.05). Various FDG uptake was observed in many organs, especially the laryngeal muscle, the cervical muscle, and the heart. In our study, there was no facter which caused FDG uptake in organs except for the fasting time and the value of free fatty acid in the heart. Such analysis of whole-body FDG distributions in the normal subjects is valuable for tumor detection with FDG-PET.

Adult↗
PubMed1998

Tissues exhibiting inhibitory [correction of inhibiory] and repulsive activities during the initial stages of neurite outgrowth from the dorsal root ganglion in the chick embryo.

To elucidate the mechanisms underlying the projection of dorsal root ganglion (DRG) axons into the dorsal root entry zone in the dorsolateral region of the spinal cord, we examined tissue interactions which affect neurite outgrowth from DRG. We cultured explants or dissociated cells of DRG from embryonic day 4 (E4) chick embryos in combination with E3 spinal cord, notochord, and dermomyotome in three-dimensional collagen gels. The ventral spinal cord, notochord, and dermomyotome, which are located close to the initial projection pathway of DRG but do not receive direct innervation, strongly inhibited DRG neurite outgrowth and repelled DRG neurites. These inhibitory/repulsive cues appear diffusible in nature, because this activity was observed in the absence of direct contacts between tissue explants and DRG neurites. Furthermore, in heterochronic cultures, E9 DRG lost its responsiveness to inhibitory/repulsive factors from E3 ventral spinal cord, while retaining responsiveness to E3 notochord and dermomyotome, suggesting that the E3 ventral spinal cord may secrete a different inhibitory/repulsive signal than notochord and dermomyotome. Putative inhibitory/repulsive signals secreted from tissues along the axonal pathway may serve to guide growing DRG axons to the dorsal root entry zone.

Animals↗
PubMed1998

Platelet-activating factor receptor antagonist attenuates endotoxin-induced vascular hyporeactivity in the pithed rat.

The role of platelet activating factor (PAF) and nitric oxide (NO) in the endotoxin-induced hyporeactivity to noradrenaline was studied in the pithed rat. Pressor dose-response curves to noradrenaline (0.01-10 microg/kg, i.v.) were made starting 1 h after the administration of endotoxin (0.5 mg/kg, i.v.) to the rats. Saline was administered to the control rats. The PAF receptor antagonist, TCV-309 (3-bromo-5-[N-phenyl-N-[2-[[2-(1,2,3,4-tetrahydro-2-isoquinolylcarbon yloxy)ethyl]carbamoyl]ethy]carbamoyl]-1-propylpyridinium nitrate, 100 microg/kg, i.v.), or the NO synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMMA, 30 mg/kg, i.v.), was administered to the endotoxin-treated rats 20 or 10 min before the noradrenaline challenge. L-NMMA reversed endotoxin-induced hyporeactivity completely. TCV-309 produced a significant, but partial attenuation of the hyporeactivity to noradrenaline (P < 0.01). There was still significant hyporeactivity when compared with the control rats (P < 0.01) and the L-NMMA-treated endotoxin-administered rats (P < 0.05). These data suggest that endogenous PAF contributes to the vascular hyporeactivity to noradrenaline induced by endotoxin and that NO plays a major role in the endotoxin-induced hyporeactivity.

Animals↗
PubMed1998

Transesophageal echocardiographic evaluation during negative-pressure ventilation using the Hayek oscillator.

OBJECTIVES: To evaluate the effects of negative-pressure ventilation (NPV) on hemodynamics using the Hayek oscillator (Breasy Medical Equipment, London, UK) and to determine whether the oscillation frequency can modify the hemodynamics, assessed by transesophageal echocardiography (TEE). DESIGN: A prospective study. SETTING: A university hospital. PARTICIPANTS: Eleven American Society of Anesthesiologists class I patients undergoing orolaryngeal surgery. INTERVENTIONS: The ultrasound probe was inserted under general anesthesia. After baseline measurements were determined during spontaneous breathing, the frequency was changed from 30 to 60 to 120 cycles/min, consecutively. The left ventricular end-diastolic area (LVEDA), end-systolic area (LVESA), fractional area change (LVFAC), and end-systolic wall stress (ESWS) were determined. The velocities of the pulmonary artery (PA) flow, pulmonary venous (PV) flow, and transmitral flow were measured by pulsed Doppler techniques. MEASUREMENTS AND MAIN RESULTS: PaO2 increased and PaCO2 decreased significantly. NPV caused a significant increase in the LVEDA, whereas it did not significantly change the PA velocity. ESWS, an index of afterload, remained unchanged. CONCLUSION: The authors conclude that NPV using the Hayek oscillator induces an increase in the LVEDA without any changes in PA velocity, suggesting increased transmural pressure rather than increased preload, and that the three different frequencies do not modify the effects on the hemodynamics.

Adolescent↗
PubMed1998

Relevance of a new impedance matching, or subtrap, method for the reduction of pain during hyperthermia.

Capacitive heating is widely used in hyperthermic treatment of human malignancies. However, the pain on the body surface or thermoesthesia in the subcutaneous fatty layer may prevent an elevation of temperature in the tumors. Impedance matching is improved by a subtrap method entailing the application of two copper plates (10 x 850 x 0.06 mm) as a subtrap circuit to each of two capacitive electrodes. In a clinical trial the Tmax, Tave, Tmin for the subtrap method were all higher in comparison with those for the conventional technique (42.5 +/- 0.7 degrees C, 41.9 +/- 1.0 degrees C, 41.3 +/- 1.1 degrees C vs. 41.1 +/- 1.5 degrees C, 40.6 +/- 1.3 degrees C, 40.0 +/- 1.3 degrees C). Although the maximal radiofrequency (RF) power applied to patients was higher with the subtrap method (875 +/- 189 W vs. 763 +/- 200 W), the incidence of surface pain was reduced dramatically. It is concluded that the subtrap method substantially improves the RF capacitive heating of deep-seated tumors.

Adolescent↗