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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 937 records · Page 52Linked to original sources

Emergency balloon embolization for carotid artery rupture secondary to postoperative infection.

Two cases of carotid artery rupture due to postoperative infection were treated successfully with an emergency endovascular technique. A detachable balloon was attached to a 2 Fr microcatheter and was introduced through a 9 Fr guiding catheter. The balloons were detached at the rupture site and just proximal to the lesion. This technique has several advantages over surgical procedures.

Aged↗

Significance of atretic follicles as the site of androgen production in polycystic ovaries.

To examine androgenic potential of polycystic ovaries (PCO), slices of follicular and stromal tissues from the same ovary obtained by wedge resection from two markedly, two moderately and one slightly enlarged PCO were incubated separately with [1-14C] acetate. Incorporation into progestins, androgens and estrogens was assessed by reverse dilution technique with recrystallization to constant specific activity. Although the greatest incorporation into androstenedione with much lesser incorporation into testosterone and dehydroepiandrosterone was observed with all the five follicles, the amount of incorporation into the three steroids increased gradedly with histologically defined magnitude of thecal cell hyperplasia in atretic follicles. Only the stromal tissues from two markedly enlarged PCO produced androgens with a similar pattern of 14C distribution among the steroids, thereby incorporation into the three androgens remaining 5.5% or less of that by the follicles from the same ovary. Preoperative levels of plasma androstenedione and urinary 17-ketosteroids were shown to increase in four patients with PCO containing atretic follicles with thecal cell hyperplasia, but not in one patient with slightly enlarged PCO containing atretic follicles without thecal cell hyperplasia. It is inferred that atretic follicles with thecal cell hyperplasia is a significant source of androgen overproduction by PCO.

Acetates↗

Magnetic resonance imaging of an angiomyolipoma of the liver.

A case of hepatic angiomyolipoma and its imaging features are presented. Computed tomography of the liver showed a low-density mass without obvious fat. T1-weighted magnetic resonance images revealed a low-signal-intensity mass containing some tiny high-signal-intensity foci. One of the high-signal-intensity foci was found by histology to represent the fat component of the tumor.

Angiomyolipoma↗

Successful treatment of a 93-year-old patient with hypoplastic acute monocytic leukemia using macrophage colony-stimulating factor.

A 93-year-old patient with hypoplastic acute monocytic leukemia (AMoL) achieved a complete remission after macrophage colony-stimulating factor (M-CSF) therapy. Initially, the patient was treated with a low dose of cytarabine, but this treatment proved ineffective. M-CSF was administered for 14 days by drip intravenous infusion, 800 x 10(4) units per day. After a gradual decrease in the number of leukemic cells, a rapid increase in neutrophils was observed in the peripheral blood, and a bone marrow examination 22 days after discontinuation of M-CSF medication revealed a complete remission. These findings suggest that M-CSF may be useful in treating some elderly patients who have hypoplastic AMoL.

Aged↗

Comparisons between invasive and noninvasive determinations of embryonic heart rate in chickens.

The embryonic heart rate (HR) of chicken eggs was determined by ballistocardiography, electrocardiography, impedance-cardiography and acoustocardiography. The effects of these different methods on the HR were examined for young (12-day-old) and late (16- and 18-day-old) embryos. Ballistocardiography is a non-invasive method. Nevertheless, the mean HRs determined using this method at 5-hr intervals were significantly different in many embryos. This difference was caused by the natural variability of embryonic HR. The statistical analyses indicated that any of these four methods did not influence the HR measurement and can be used as a simple means for determination of the embryonic HR.

Acoustic Stimulation↗

MR visualization and clinical significance of the anterior longitudinal epidural venous plexus in cervical extra-axial lesions.

A thin band of intermediate signal intensity behind the cervical vertebral bodies, demonstrated on sagittal MR images, was attributed to the anterior longitudinal epidural venous (AEVP). Percentage visualization and clinical significance of this structure were evaluated in extra-axial lesions of the spinal cord. In review of 50 normal controls, the percentage visualization of this structure at each cervical vertebral level was 25.5% on T1 weighted sagittal SE images, while that of T2 or proton density weighted SE images was 26.0%. AEVP was demonstrated by sagittal MRI in 29 of 128 extra-axial lesions of the cervical cord (22.7%), including cervical spondylosis, ossification of the posterior longitudinal ligament (PLL), herniated disk and spondylosis at a single level. AEVP in these conditions was often thickened compared with normal controls, probably due to venous engorgement and contribution of the dura mater and PLL. Posterior displacement of this structure or "lifted band appearance" indicated herniated disk or posteriorly protruding osteophyte, demonstrating true anteroposterior diameter of the spinal canal. Demonstration of AEVP on sagittal MRI was important in the diagnosis of extra-axial lesions of the cervical cord.

Cervical Vertebrae↗

MRI findings of hypothalamic hamartoma: report of five cases and review of the literature.

Hypothalamic hamartoma is a relatively rare congenital malformation, associated with the clinical presentation of precocious puberty of central type. Five cases with hypothalamic hamartoma are reported here, with an emphasis on MR appearance. The most common presentation of hypothalamic hamartoma was a small and well defined mass in the inferior aspect of the hypothalamus, showing isointensity on T1 weighted images and hyperintensity on T2 weighted images compared with the gray matter. The previous reports with MRI description are reviewed and compared with the present results.

Child, Preschool↗

Studies on placental inhibition of platelet aggregation: a comparison of human syncytiotrophoblast brush border and basal plasma membranes.

We compared the platelet aggregation inhibiting activity of human placental syncytiotrophoblast brush border membrane vesicles (BBMV) and basal plasma membrane vesicles (BpMV), and obtained the following results. Strong platelet aggregation inhibiting activity is found in placental BBMV. BBMV inhibited platelet aggregation induced by ADP (adenosine diphosphate) and arachidonic acid in a way which depended on the protein concentration of BBMV added. In contrast, BpMV showed no detectable platelet aggregation inhibiting activity. Quite high ADP degrading activity (ADPase activity) was present in the placental BBMV. ADP was quickly degraded by BBMV. In contrast, BpMV did not degrade ADP so quickly. Platelet TXB2 production was almost completely abolished at the protein concentration of 40 micrograms/ml of BBMV. In contrast, BpMV did not significantly inhibit platelet TXA2 (TXB2) production. These results show that syncytiotrophoblast brush border and basal plasma membranes of the human placenta have markedly different properties with respect to platelet aggregation inhibiting activity.

Adenosine Diphosphate↗

Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles.

We investigated the platelet aggregation inhibiting activity of human placental brush border membrane vesicles (BBMV) and obtained the following results. A strong platelet aggregation inhibiting activity existed in placental BBMV. The BBMV inhibited the platelet aggregation induced by ADP, arachidonic acid, collagen and ristocetin in a dose-dependent manner. The protein concentration of BBMV giving 50 per cent inhibition was 52 +/- 6 micrograms/ml for ADP-induced platelet aggregation, 21 +/- 2 micrograms/ml for arachidonic acid-induced platelet aggregation, 19 +/- 2 micrograms/ml for collagen-induced platelet aggregation and 107 +/- 9 micrograms/ml for ristocetin-induced platelet aggregation. There was a high level of ADP degrading activity (ADPase activity) in the placental BBMV. ADP degrading activity of the BBMV: 10.5 +/- 0.5 mumol/mg protein/min was 21 times greater than that of homogenate of the placental villi. The placental BBMV inhibited platelet TXA2 production. In the 40 micrograms/ml protein concentration of placental BBMV, platelet TXA2 production was almost completely inhibited.

Adenosine Diphosphate↗

Characterization of human placental activity for transport of taurocholate, using brush border (microvillous) membrane vesicles.

The uptake of taurocholate into brush border membrane vesicles prepared from human full term placenta was studied using a rapid filtration technique. The taurocholate uptake into brush border membrane vesicles was sensitive to extravesicular osmolarity, and pre-incubation of the brush border membrane vesicles with the taurocholate increased the uptake of taurocholate into the brush border membrane vesicles. These findings indicate that the uptake of taurocholate by brush border membrane vesicles represents transport into vesicles. The uptake of taurocholate into vesicles was not dependent on Na+ electrochemical gradient (extravesicular > intravesicular). But this uptake was markedly increased when the intravesicular space was rendered electrically more positive by the use of lowly permeant anions or valinomycin-induced K+ diffusion membrane potentials. These findings indicate that the taurocholate transport into brush border membrane vesicles was dependent on membrane potential. The initial rate of taurocholate transport into brush border membrane vesicles exhibited saturation kinetics with respect to the taurocholate concentration, an apparent Km of 67 microM and Vmax of 0.30 nmol/mg protein/20 sec were calculated.

Anions↗

Properties of ADP-degrading activity of human placental syncytiotrophoblast brush border membrane vesicles.

The enzymatic properties of ADP (adenosine diphosphate) degradation in human placental syncytiotrophoblast brush border membrane vesicles (BBMV) were explored and the following results were obtained. BBMV had high ADP degrading activity compared to homogenate of placental villi. ADP degrading activity of BBMV; 1.05 +/- 0.05 mumol/mg protein/min placental villi was 21 times higher than that of homogenate of placental villi. Hydrolysis of ADP by BBMV follows Michaelis-Menten saturation kinetics with an apparent Km of 10.9 +/- 0.8 microM and Vmax of 2.10 +/- 0.17 mumol/mg protein/min. The enzyme has a divalent cation requirement. EDTA (2 mM) was found to abolish ADP degrading activity but this could be restored by the addition of either magnesium or calcium ions. Maximum enzyme activity of ADP degradation in BBMV was observed at a pH close to 8.0. The enzyme was insensitive to vanadate, levamisole, oligomycin, ouabain and N-ethylmaleimide (NEM), omeprazole and adenosine (5') pentaphospho (5') adenosine.

Adenosine Diphosphate↗

The effect of short-term basal insulin supplementation with human ultralente insulin on diurnal glycemic control in NIDDM patients.

The effect of short-term insulin treatment with a long-acting insulin preparation, Ultratard HM (U-HM) was investigated in eight non-insulin-dependent diabetes mellitus (NIDDM) patients whose previous glycemic control using diet was judged unsatisfactory. The treatment consisted of one daily pre-breakfast injection of U-HM (0.3 IU/kg) for 8 days. Glycemic control, assessed by mean plasma glucose (PG) daily profile and M-value, was improved significantly after U-HM treatment (mean PG and M-value, before: 223 +/- 19 mg/dl, 38.2; on the last day of U-HM: 151 +/- 11 mg/dl, 16.3; P less than 0.001; P less than 0.05). Serum insulin (IRI) reached a peak at 14:30 h during U-HM treatment, and mean IRI level increased during U-HM treatment (before: 14.0 +/- 2.8; during U-HM: 19.9 +/- 2.7 microU/ml). The mean C-peptide (CP) level decreased during U-HM treatment. Daily urinary CP excretion also decreased during U-HM treatment (before: 52.7 +/- 4.2; during U-HM: 34.8 +/- 4.2 micrograms/24 h). The data indicated that a single daily injection of U-HM was effective to improve whole-day glycemic control in NIDDM patients.

Adult↗

Calcium crystal deposition in cervical ligamentum flavum: CT and MR findings.

We report three patients with calcium pyrophosphate dihydrate crystal deposition disease within the ligamenta flava of the cervical spine who presented with progressive myelopathy. Plain radiography showed oval calcified nodules at the level of C4-C5 and C5-C6. On computed myelography, oval calcified nodules were seen in the ligamenta flava of the posterior cervical spinal canal compressing the dural sac. Magnetic resonance revealed oval corresponding hypointense foci both on T1-and T2-weighted images. In two cases, the cervical cord showed hyperintensity at the compression site on T2-weighted images.

Aged↗

MR angiography of the persistent trigeminal artery variant.

OBJECTIVE: To evaluate the MR angiographic findings of the persistent trigeminal artery variant (PTAV) and to discuss its clinical implications. MATERIALS AND METHODS: We reviewed time-of-flight MR angiography including individual source imaging in three patients with PTAV, which had been recognized as an incidental finding on conventional arteriography. In all cases, MR angiography was performed at 1.5 T. RESULTS: MR angiography demonstrated the PTAVs as hyperintense structures originating from the precavernous portion of the internal carotid artery, running within or very close to the Meckel cave and near the trigeminal nerve root, and reaching the posterior fossa (cerebellar arteries) without joining the basilar artery. Spin echo imaging failed to demonstrate the PTAVs. CONCLUSION: Source imaging of MR angiography helped demonstrate PTAV and its adjacent structure. Knowledge of the presence and course of this anomalous vessel is useful for various treatment strategies.

Adolescent↗

Evaluation of vascular compression in trigeminal neuralgia by 3D time-of-flight MRA.

OBJECTIVE: Our goal was to assess the usefulness of 3D images in the preoperative evaluation of 16 patients with surgically confirmed trigeminal neuralgia. MATERIALS AND METHODS: The axial source images from 3D TOF MRA were evaluated for a total of 32 sides by two observers in a blinded manner, focusing on the presence of the neurovascular compression and the identification of compressing vessels. All 3D images including coronal orientation and gadolinium-enhanced images were reviewed retrospectively by another two observers together with the surgical findings. RESULTS: In the blinded study with axial 3D images, the sensitivity was 75 and 75% with a specificity of 75 and 69% for observers A and B, respectively. By reviewing the coronal images, the relationship between trigeminal nerve and vessels became clearer, especially in sandwich-type compression. With gadolinium-enhanced images, three vessels that were not shown in the nonenhanced images could be identified. On the asymptomatic side, vascular compression could not be excluded retrospectively in five cases. CONCLUSION: Nonenhanced axial images may not display small arteries or veins that are compressing the trigeminal nerve. Gadolinium enhancement will be necessary for those patients without demonstrable compression on nonenhanced examination. Coronal images are also helpful in the evaluation of vascular compression.

Adult↗