Search PubMed⌕ Search

Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 1,135 records · Page 63Linked to original sources
PubMed1988

[Dissecting aneurysm of the vertebral artery--report of two cases and review of the literature].

Two cases of dissecting aneurysm of the vertebral artery are reported and the 70 cases reported previously are reviewed. Case 1 showed Wallenberg's syndrome following sudden headache on the right side without SAH. Angiograms demonstrated the "pearl and string sign" on the right vertebral artery, characteristic of a dissecting aneurysm. Through a right suboccipital craniectomy, the right vertebral artery was found to be discolored purplish-red and swollen, so the proximal vertebral artery was clipped. The postoperative course was uneventful. Case 2 showed Wallenberg's syndrome with antecedent headache. CT scan was normal and lumber puncture revealed xanthochromic CSF, which was attributed to a SAH several days before. Angiograms disclosed the "pearl and string sign" on the right vertebral artery, and right vertebral artery clipping was performed. Postoperatively it was uneventful. Intracranial dissecting aneurysms of the vertebrobasilar system are not as rare as previously thought. They can often be overlooked as fusiform aneurysms or as thrombosis associated with SAH and/or ischemic attacks. The difficulty in diagnosis, leads to a high morbidity and mortality rate. Recently many cases have been reported in sequence. These cases involving SAH were successfully treated by surgical procedure. However in addition to our cases, only two cases of successful surgical treatment after ischemic stroke, have been reported. We emphasize that surgical intervention should be carried out for dissecting aneurysms of the vertebro-basilar system, even without SAH, to prevent further dissection which could cause SAH or/and further brainstem infarction. Proximal vertebral artery occlusion is the most beneficial treatment of choice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[A case of colloid cyst of the third ventricle].

Colloid cysts of the third ventricle are rare, accounting for less than 1% of all intracranial neoplasms. However, its incidence will increase with increased use of CT scan and MRI. The symptomatology is principally acute or chronic hydrocephalus obstructing the foramen of Monro, and the origin of this cyst is controversial, neuroepithelial or endodermal. We report a case of colloid cyst of the third ventricle, associated with cavum veli interpositi. The patient, a 46-years-old female, had suffered from headache, ataxic gait and tremor lasting 6 months. CT scan and homogenous high signal intensity by SR (2450/450) MR image, detected a small round mass in the anterior part of the third ventricle that was of homogenous high density, but without the effect of enhancement. The lateral ventricle was markedly dilated, and a large cavum veli interpositi was found between the third ventricle and the corpus callosum. The cyst was totally removed by transventricular approach, and the result was satisfactory. We reviewed literatures and discussed MRI findings of colloid cysts of the third ventricle. Because of the presence of microvilli covered with coating materials seen in electron microscopic study, we suggested that the colloid cyst was endodermal in origin.

Brain Diseases↗
PubMed1988

Studies on the lipid and apolipoprotein compositions of two species of apoA-I-containing lipoproteins in normolipidemic males and females.

Two species of apoA-I-containing lipoproteins (A-ILp), lipoprotein containing apoA-I and apoA-II (LpA-I/A-II) and lipoprotein containing apoA-I but no apoA-II (LpA-I), have been isolated from 20 normolipidemic adults (10 males and 10 females) by immunoaffinity chromatography. We have characterized the lipid and apolipoprotein compositions in these lipoproteins, and found sex differences. In A-ILp, the levels of lipids, except triglyceride, and the level of apoE were significantly higher in females than in males. In LpA-I/A-II, sex differences were found only in the levels of apoA-I and apoE. In LpA-I, the levels of all lipids, except triglyceride, and the level of apoA-I were significantly higher in females than in males. Therefore, sex differences observed in A-ILp appear to be due primarily to the differences found in LpA-I. Of considerable significance is our finding that the ratio of cholesteryl ester to total cholesterol in LpA-I was significantly lower than that in LpA-I/A-II in both males and females. This might suggest that LpA-I could be a carrier of free cholesterol.

Adult↗
PubMed1988

[Postoperative pulmonary embolism in neurosurgical practice: report of two cases].

Pulmonary embolism following postoperative deep venous thrombosis is a very serious complication with a high mortality rate. Though this disorder has been thought to be rare in Japanese, its occurrence seems to be increasing recently because of changes in eating habits, increase of average age and the frequent practice of venous catheterization. Two cases of the pulmonary embolism following deep venous thrombosis after surgery are reported, and possible causes of the deep venous thrombosis are discussed. Case 1: A 48 year-old obese female was operated on for a posterior fossa dural arteriovenous malformation. On the 4th postoperative day, she developed a pain and swelling in the left leg and low back pain. On the 18th postoperative day, she fell into a state of shock following the sudden onset of a severe back pain and respiratory distress. After diagnosis of the pulmonary embolism, she was immediately treated with urokinase, warfarin and aspirin. Her obesity was considered to be one of the risk factors of the postoperative deep venous thrombosis. Case 2: A 62 year-old female with a ruptured cerebral aneurysm could not get out of bed because of postoperative mental disturbance. A central venous pressure catheter was inserted into the right femoral vein for two weeks postoperatively. One month after surgery, she complained of swelling and a dull pain in the right leg without cardiorespiratory symptoms. Lung perfusion scintigraphy showed asymptomatic pulmonary embolism. She was treated immediately. Both long bed rest and femoral venous catheterization were considered as risk factors possibly leading to deep venous thrombosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗
PubMed1988

Developmental and radiological anatomy of the superficial cerebral convexity vessels in the human fetus.

The superficial cerebral vessels on the convex side of the cerebral hemisphere were investigated using 40 brains of aborted human fetuses (ranging from 2 to 7 months of gestational age), injected with radiopaque material either through the arterial or venous system. These brains, particularly their vessels, were studied in detail through stepwise roentgenography in stereo-pairs, photography and careful dissections. Morphological changes of the superficial vessels of the cerebral convexity reflect the developmental alterations of the cerebral structures, particularly those of the opercula and cerebral sulci. Between the gestational ages of 3 and 4 months, the middle cerebral artery and its tributaries run radially on the sylvian fossa and over the convexity. Anastomoses among the peripheral branches of the anterior, middle and posterior cerebral arteries take place on the convex side of the hemisphere. At the ages of 3 and 4 months, the middle cerebral vein and its tributaries are well developed compared with the superior and inferior cerebral (or ascending and descending cortical) veins. The middle cerebral vein and its tributaries rapidly regress from the 5th to 7th month. The superior and inferior cerebral veins, on the other hand, develop rapidly during this period. Owing to the development of the opercula and resultant depression of the insula, after seven months of gestation the middle cerebral artery and its branches, begin to differentiate into the vallecular (related to the sylvian vallecula or fronto-temporal notch), insular (related to the insular cortex), opercular (related to the frontal, parietal and temporal opercula) and convexity segments (related to the convex side of the hemisphere). The anastomotic veins of Trolard and Labbé are also recognizable at this stage. The superficial sylvian vein in the process of formation may also be detected. The configuration of the cerebral vessels on the convex side of the hemisphere is also affected greatly by the development of the cerebral sulci. These cerebral vessels may run along, or dip into the sulci. Since the development of the superficial cerebral vessels is closely related to that of the cerebral mantle, these studies should be correlated to detail with those of developmental alterations of the intraparenchymal vessels (medullary arteries and veins). The latter investigation will be presented in a future communication.

Cerebral Arteries↗
PubMed1988

[Continuous intra-arterial infusion chemotherapy for inoperable retroperitoneal liposarcoma--a case report].

A case of an inoperable recurrent retroperitoneal liposarcoma, histologically diagnosed as being a mixed myxoid type and a round cell type, which was treated by continuous intra-arterial infusion chemotherapy, is reported. The authors applied this treatment method using adriamycin and 5-FU via the feeding arteries, i.e., the superior and the inferior mesenteric arteries. The tumor showed remarkable regression with no severe complications, even though general chemotherapy using adriamycin proved to be ineffective. This infusion method was thus evaluated as highly effective.

Adult↗
PubMed1988

Still's disease associated with necrotizing lymphadenitis (Kikuchi's disease): report of 3 cases.

Necrotizing lymphadenitis (Kikuchi's disease) is recognized as one of the benign lymphadenopathies. Previously, this condition has not been described in Still's disease which is frequently associated with lymphadenopathy. We report 3 cases of Still's disease, 2 in adults and 1 in an older child, with the findings of necrotizing lymphadenitis on lymph node biopsy. Considering the common infectious and/or immunologic etiologies described in both disorders, coexistence of both conditions suggests the possibility that they share a common etiology.

Adolescent↗
PubMed1987

A water-soluble form of penicillin-binding protein 2 of Escherichia coli constructed by site-directed mutagenesis.

Penicillin-binding protein (PBP) 2 of Escherichia coli is located in the cytoplasmic membrane. The N-terminal hydrophobic segment (31 amino acids, residues 15-45) of PBP2 was removed by a deletion in the PBP2 gene by site-directed mutagenesis, resulting in the production of a water-soluble form of PBP2 (called PBP2*). PBP2* retained the penicillin-binding activity, was localized in the cytoplasm and was overproduced under the control of the lpp-lac promoter. this indicates that the removed hydrophobic segment is an uncleaved signal sequence required for translocation of PBP2 across the cytoplasmic membrane, and also suggests that the segment anchors the protein to the membrane.

Bacterial Proteins↗
PubMed1987

A model of evolution for accumulating genetic information.

By taking into account recent knowledge of multigene families and other repetitive DNA sequences, a model of evolution by gene duplication for accumulating genetic information is studied. Genetic information is defined as the sum of distinct functions that the gene family can perform. A coefficient, "genetic diversity" is defined and used in this study, that is highly correlated with genetic information. Initially, a multigene family with a few gene copies is assumed, and natural selection starts to work on this gene family to increase genetic diversity contained in the gene family. As an important mechanism, unequal crossing-over is incorporated. Together with mutation, it is responsible for supplying genetic variability among individuals for selection to work. A specific model, in which individuals with less genetic diversity are selectively disadvantageous, has been studied in detail. Through approximate theoretical analysis and extensive Monte Carlo studies, it has been shown that the system is an extremely efficient way to accumulate genetic information. For attaining one gene, the genetic load is much smaller under this model than under the traditional model of natural selection. The model may be applied to the process of origin of multigene families with diverse copy members such as those of immunoglobulin or cytochrome P450. In general, the process of creating new genes by duplication might be somewhere between the present and the traditional models.

Biological Evolution↗
PubMed1987

Very slightly deleterious mutations and the molecular clock.

The model of very slightly deleterious mutations was examined from the standpoint of population genetics in relation to the molecular evolutionary clock. The distribution of selection coefficients of mutants (in terms of amino acid changes) with small effect is thought to be continuous around zero, with an average negative value. The variance of selection coefficients depends upon environmental diversity and hence on total population size of a species. By considering various examples of amino acid substitutions, the average and standard error of selection coefficients and the reciprocal of population size are assumed to have similar values. The model predicts negative correlation between evolutionary rate and population size. This effect is expected to be partially cancelled with the generation time effect of intrinsic mutation rate. Implications of this prediction on the molecular evolutionary clock are discussed.

Amino Acids↗
PubMed1987

Characterization of photoreceptor cell differentiation in the rat retinal cell culture.

Photoreceptor cell differentiation in the rat retina was studied in vivo and in vitro, using an immunohistochemical method to demonstrate opsin-like immunoreactivity. Cells in a dissociated monolayer culture expressed some properties characteristic of rat rod cells developing in vivo, including a ciliary structure and opsin-like immunoreactivity. Immunoblot analysis revealed that cultured retinal cells synthesize a polypeptide with the same molecular weight as that synthesized by the intact retina. Although the outer segment (OS) was not present in the culture, immunoreactive cells possessed a ciliary structure. Opsin-like immunoreactivity was found on the plasma membrane, including the cilia. The neuritic extensions were also intensely stained. In mature rod cells of the intact rat retina, opsin was detected only on the OS but, during development, it was found both in the somatic region of the rod cells and on the differentiating OS. During maturation of rod cells opsin immunoreactivity seemed to shift to the OS from other locations. However, some "displaced" photoreceptor cells, found in the inner nuclear layer and extending fibers bipolarly, retained immunoreactivity throughout their structure. The absence of polarized distribution of opsin in these cells is considered to be due to an abnormal environment, which may also be the case with cultured retinal cells. The present culture conditions will offer a useful model system to understand the cellular mechanism of the hereditary retinal dystrophy of rodent animals in which photoreceptor cells selectively degenerate.

Animals↗
PubMed1987

Effects of antimutagenic flavourings on SCEs induced by chemical mutagens in cultured Chinese hamster cells.

Effects of antimutagenic flavourings such as vanillin, ethylvanillin, anisaldehyde, cinnamaldehyde, coumarin and umbelliferone on the induction of SCEs by MMC were investigated in cultured Chinese hamster ovary cells. None of these 6 flavourings showed any SCE-inducing activity by themselves. However, an obvious increase in the frequencies of SCEs was observed when MMC-pretreated cells were cultured in the presence of each flavouring. All these compounds have either an alpha, beta-unsaturated carbonyl group or a carbonyl functionality neighbouring the phenyl group which may react with an enzyme SH-group and cause higher-order structure changes. SCE-enhancing effects of vanillin were further investigated on 6 other kinds of mutagens. Vanillin was also effective on SCEs induced by EMS, ENNG, ENU or MNU. On the other hand, MMS- or MNNG-induced SCEs were not influenced at all by vanillin. SCE-enhancing effects of vanillin seemed to be dependent on the quality of lesions in DNA.

Animals↗
PubMed1987

Unusual genetic codes and a novel gene structure for tRNA(AGYSer) in starfish mitochondrial DNA.

The nucleotide sequence of a 3849-bp fragment of starfish mitochondrial genome was determined. The genes for NADH dehydrogenase subunits 3, 4, 5, and COIII, and three kinds of (tRNA(UCNSer), tRNA(His), and tRNA(AGYSer) were identified by comparing with the genes of other animal mitochondria so far elucidated. The gene arrangement of starfish mitochondrial genome was different from those of vertebrate and insect mitochondrial genomes. Comparison of the protein-encoding nucleotide sequences of starfish mitochondria with those of other animal mitochondria suggested a unique genetic code in starfish mitochondrial genome; both AGA and AGG (arginine in the universal code) code for serine, AUA (isoleucine in the universal code but methionine in most mitochondrial systems) for isoleucine, and AAA (lysine) for asparagine. It was also inferred that these AGA and AGG codons are decoded by serine tRNA(AGYSer) originally corresponding to AGC and AGU codons. This situation is similar to the case of Drosophila mitochondrial genome. Variations in the use of AGA and AGG codons were discussed on the basis of the evolution of animals and decoding capacity of various tRNA(AGYSer) species possessing different sizes of the dihydrouridine (D) arm.

Animals↗
PubMed1987

Pharmacokinetics and depressor effect of delapril in patients with essential hypertension.

The pharmacokinetics and depressor effect of a nonsulfhydryl angiotensin-converting enzyme inhibitor, delapril, was assessed by administering a single dose of 30 mg to nine patients with mild to moderate essential hypertension. Orally administered delapril is a prodrug and must be deesterified to its active metabolites, delapril diacid and 5-hydroxy delapril diacid. The pharmacokinetic parameters for delapril, delapril diacid, and 5-hydroxy delapril diacid were, respectively: t 1/2 0.30, 1.21, and 1.40 hours; Cmax 489, 635, and 229 ng/ml; AUC 572, 1859, and 948 ng X hr/ml. Delapril produced significant decreases in systolic blood pressure and angiotensin-converting enzyme activity 24 hours after dosing. There were no significant changes in the endogeneous creatinine clearance after the drug. Thus delapril may represent a useful antihypertensive agent for control of blood pressure in patients with essential hypertension.

Adult↗