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Biomedical subjects

T Yamaki

Publications and source records attributed to T Yamaki.

At least 91 records · Page 5Linked to original sources
PubMed1992

Cerebral salt wasting syndrome distinct from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH).

Two cases with pituitary tumour developed postoperative hyponatraemia which was not caused by inappropriate secretion of antidiuretic hormone. The one case with non-functioning macro-adenoma showed severe hyponatraemia (116 mEq/l) on day 11 after trans-sphenoidal surgery in association with diabetes insipidus (DI). The patients was treated by aqueous pitressin and saline administration to control urinary output and keep positive salt balance at the same time. The other case with GH-producing macro-adenoma showed progressive negative sodium balance with the total loss of 644 mEq resulting in hyponatraemia of 133 mEq/l. This was corrected by additional salt intake. The plasma atrial natriuretic polypeptide (ANP), antidiuretic hormone (ADH) as well as aldosterone levels were normal in the latter case. These patients were considered to manifest primary salt wasting disorder, which should be clearly differentiated from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH).

Adenoma↗
PubMed1992

Pathological study of diffuse axonal injury patients who died shortly after impact.

It is generally considered that axonal injury is apparent only on electron microscopy in the very early stage after a closed head injury. To clarify the pathological findings in head injury patients dying very shortly after the impact, we analyzed 8 fatal cases of diffuse axonal injury (DAI) who underwent medicolegal autopsy at the Department of Forensic Medicine of Kyoto Prefectural University of Medicine. Seven cases died within one hour after injury and another one case died 3 days after injury. We studied these cases macroscopically, microscopically, and electron microscopically. Macroscopically all cases showed the typical findings of diffuse axonal injury. Microscopical study of the cases who died within one hour revealed no characteristic findings of DAI such as appearance of retraction balls or microglia. On the other hand, in the case who died only 3 days after injury it showed the typical retraction balls. Electron microscopic study showed the remarkable destruction of cytoskeletal structure of axons in all cases. From our results, it is reasonable to speculate that DAI may be common among head injury patients who die very soon after the impact.

Adolescent↗
PubMed1992

[Zygomatic arch fractures; a neurosurgical viewpoint].

Depressed fractures of the zygomatic arch are often overlooked due to local swelling associated with the injury. However, such fractures are easily detected using roentgenography in superioinferior projection and/or bone image CT examinations of the zygomatic arch. Ten patients with depressed fracture of the zygomatic arch were treated surgically. Nine underwent an operation by the Gillies method within 15 days after the injury and showed good results. In the remaining patient, the operation performed on the 27th day after the injury failed to reconstruct the zygomatic arch perfectly, even when the open procedure was used. The most important point in these cases is the detection and surgical treatment of the fracture at an early stage. Patients with trismus and depressed fracture of the zygomatic arch should be operated on within two weeks after injury. During this period, the surgical method reported by Gillies can be performed easily and also produces successful results.

Adult↗
PubMed1991

Shaping and reshaping of salmonid genomes by amplification of tRNA-derived retroposons during evolution.

Three families of tRNA-derived repeated retroposons in the genomes of salmonid species have been isolated and characterized. These three families differ in sequence, but all are derived from a tRNA(Lys) or from a tRNA species structurally related to tRNA(Lys). The salmon Sma I family is present in the genomes of two species of the genus Oncorhynchus but not in other species, including five other species of the same genus. The charr Fok I family is present only in four species and subspecies of the genus Salvelinus. The third family, the salmonid Hpa I family, appears to be present in all salmonid species but is not present in species that are not members of the Salmonidae. Thus, the genome of proto-Salmonidae was originally shaped by amplification and dispersion of the salmonid Hpa I family and then reshaped by amplification of the Sma I and Fok I families in the more recently evolved species of salmon and charr, respectively. We speculate that amplification and dispersion of retroposons may have played a role in salmonid speciation.

Animals↗
PubMed1991

Vascularized omentum graft for the reconstruction of the skull base after removal of a nasoethmoidal tumor with intracranial extension: case report.

A 16-year-old boy with rhabdomyosarcoma occupying the nasal cavities and the ethmoid sinus with intracranial extension underwent transcranial surgery. The intradural tumor was resected first with the affected dura of the anterior skull base, and the dural defect was repaired with fascia harvested from the sheath of the rectus abdominis muscle. The remaining tumor contiguous to the nasal cavities was completely extirpated. The cranial cavity was then exposed to the opened nasal cavities, where a revascularized omental graft was used to separate these compartments. Lyophilized dura was placed beforehand beneath the omental graft, as a roof to the nasal cavity, and was removed 3 weeks later through the nostril. A bony skull base repair was performed over the omentum using the inner table of the bone flap. Subcutaneous fat from the abdomen was placed on the bone graft for fixation and as an additional seal for the dural defect. Reconstruction of the anterior skull base with a vascularized omental transfer provides an efficient barrier to the nasal cavity. It also serves as an excellent supporting structure for regeneration of the mucosal epithelium of the nasal cavities.

Adolescent↗
PubMed1990

Conversion of big endothelin-1 by membrane-bound metalloendopeptidase in cultured bovine endothelial cells.

We propose a candidate for the "putative" endothelin (ET) converting enzyme in the cultured endothelial cells (ECs) of bovine carotid artery. The enzyme is membrane-bound, soluble in 0.5% Triton X-100, and capable of converting human big ET-1 to ET-1 by a specific cleavage between Trp21 and Val22. The conversion reached 90% after a 5-hr incubation in the presence of DFP, PCMS and pepstatin A, but it was inhibited by EDTA, omicron-phenanthroline or phosphoramidon. The enzyme is very sensitive to pH, and active only between pH 6.6 and pH 7.6. Conversion of big ET-3 by this enzyme was only 1/9 that of big ET-1. From these results, ET-1 converting enzyme in the bovine EC is most likely to be a membrane-bound, neutral metalloendopeptidase, which is much less susceptible to big ET-3.

Amino Acid Sequence↗
PubMed1990

Chronological evaluation of acute traumatic intracerebral haematoma.

Serial computed tomographic (CT) studies were performed in 48 patients with brain contusion. Traumatic intracerebral haematoma (TIH) had developed within 6 hours in 56% of the cases, within 12 hours in 81% and 100% within 24 hours from the onset. TIH reached its maximal size in 84% of the cases within 12 hours. The incidence of the appearance of TIH from brain contusion was 52%. The performance of frequent CT examination within 24 hours following head injury would help to lower the mortality rate of such trauma.

Brain Injuries↗
PubMed1990

Impairment of CO2 reactivity in severe head injury patients: an investigation using thermal diffusion method.

For measurement of the cerebral blood flow (CBF) the thermal diffusion method is quite convenient and allows the chronological measurement of CBF and CO2 reactivity of cerebral vessels. We investigated the CO2 reactivity of fifteen head injury patients. The results showed that in head injury cases, the disturbance of the CO2 reactivity correlates well to poor outcome. Using thermal diffusion method, investigations of CO2 reactivity are useful for further understanding of the physiological state of head injury patients.

Adult↗
PubMed1990

Intimal fibroelastic thickening--its etiological significance in juvenile cerebral infarction. Case report.

Recurrent occlusive stroke of the vertebrobasilar system is reported in a 16-years-old man. Multiple arterial occlusions, segmental stenosis, or irregular dilatation were found in the angiography involving both the intra- and extracranial vertebro-basilar arteries. Surgical specimen of the extracranial vertebral artery with localized irregular lumen disclosed fibroelastic thickening of the intima with mural thrombus, which were thought to be an embolic source. Etiological significance of this intimal lesion in juvenile cerebrosvascular accident is discussed.

Adolescent↗
PubMed1990

Double intracranial tumours of maldevelopmental origin--teratoma at the pineal region and an epidermoid cyst in the fourth ventricle.

A 21-year-old man with double intracranial tumours of maldevelopmental origin, teratoma at the pineal region and an epidermoid cyst in the fourth ventricle, is reported. The tumours were removed totally by multiple operations; the epidermoid cyst was resected by suboccipital craniectomy with the patient in prone position and the teratoma was removed via occipital transtentorial approach with the patient in sitting position. Maldevelopmental tumours located within the cranial cavity with different histological types such as the present case have not sofar been described. Histogenesis of these tumours is confusing because teratoma often contains tissues of epidermoid cyst. Etiological considerations for these tumours are presented and appropriate operative procedures for tumours simultaneously occurring in the pineal and the fourth ventricle are also discussed.

Adult↗
PubMed1990

Positron emission tomographic studies on cerebral hemodynamics in patients with cerebral contusion.

Positron emission tomography is currently one of the most useful methods for measurements of cerebral hemodynamics and oxygen metabolism, because it facilitates accurate analysis of the local cerebral circulation in three-dimensional quantitative images. In this study, we performed positron emission tomography studies to measure cerebral circulation in a total of 11 patients who sustained head injuries with contusion. Several parameters were measured including regional cerebral blood flow, regional cerebral blood volume, permeability, and regional cerebral metabolic rate for oxygen. Data from brains both with and without contusion were analyzed for chronological changes, in the subacute stage from the 8th to 29th day and in the chronic stage until 360 days after the injury and compared with similar data in a group of normal subjects. It was concluded that in the subacute stage, regional cerebral blood flow decreased (26 +/- 7 and 39 +/- 10 ml/100 g/min) and regional cerebral blood volume increased (5.6 +/- 1.8 and 5.4 +/- 0.9 ml/100 g) both in areas of cerebral contusion and in areas remote from cerebral contusion and that permeability increased in areas of contusion but not in remote brain areas. In the chronic stage, these parameters showed a tendency for recovery.

Adolescent↗
PubMed1990

The heterogeneity of target recognition by lymphokine-activated killer precursor cells.

Lymphokine-activated killer (LAK) cells were generated from peripheral blood lymphocytes (PBL) that were depleted of mature cytotoxic natural killer (NK) cells. PBL NK activity was abolished by pretreatment of effector cells with the toxic lysosomotropic agent L-leucine methyl ester (LME) or by depletion of effector cells by K562 monolayer absorption (MA). Both treatments markedly reduced the proportion of cells expressing NK-associated markers such as CD 16 (Leu 11b, B73.1), Leu 7, and NKH-1 (Leu 19), whereas these treatments had minimal effects on cells expressing T cell markers (CD 3, CD 4, and CD 8). LME and MA also drastically decreased the proportion of K562 target-binding lymphocytes. LAK activity against NK-sensitive and NK-resistant targets can be generated from the NK cell-depleted PBL by incubation with interleukin-2. Peak LAK activity generated from MA-treated PBL was later than the peak of LAK activity generated from either untreated or LME-treated PBL. Although MA of PBL on NK-resistant S4 sarcoma targets had little effect on NK activity, LAK activity against both K562 and S4 targets was reduced. These results suggest that there are at least three LAK precursor subpopulations in PBL: mature NK cells that can bind and kill K562 targets (LME-sensitive and MA-sensitive); "pre-NK" cells that can bind but cannot kill (LME-resistant and MA-sensitive); and non-NK cells that cannot bind and cannot kill K562 targets (MA-resistant).

Antigens, CD↗
PubMed1990

Cellular mechanisms of tumor rejection in rats.

The mechanisms of tumor rejection by cell-mediated immunity were reviewed in a rat autochthonous and syngeneic tumor-host system. The immune system could mediate a complete regression of autochthonous tumor if the tumor cells were immunogenic. Neutrophils and macrophages first appeared following transplantation of autochthonous tumor. Lymphocytes increased in the tumor tissue as the tumor began to show regression. Degenerated tumor tissue was infiltrated by macrophages and plasma cells. The identification of rat hematopoietic cells including various subsets of lymphocytes and inflammatory cells became possible owing to a variety of monoclonal antibodies reacting with these cells. Major populations of tumor-infiltrating lymphocytes (TIL) were found to be R1-3B3 (CD5)- and R1-10B5 (CD8)-positive cells in methylcholanthrene-induced autochthonous tumor. These CD5- and CD8-positive lymphocytes were also recognized in an N-nitrosourea-induced syngeneic tumor-host system and actually showed specific cytotoxicity against tumor cells in vitro. Macrophages were recognized in tumor tissues more predominantly in the early and terminal phase of tumor rejection; their functions are still uncertain but they are considered to have important immunomodulatory effects. A variety of cytokines were thought to play an important role in augmenting host immunity to achieve tumor rejection. Neutrophils in the tumor tissue were shown to produce a factor attracting lymphocytes to the tumor site, which was designated as lymphocyte migration factor. Subsequently, activities of colony-stimulating factor, interleukin-1, -2, and -3, and cytotoxic-T-cell-generating factor (CGF), which induces final maturation of cytotoxic T cells, were detected at the tumor site as well as in the regional lymph nodes and the spleen. CGF was found to be produced by W3/25 (CD4)-positive T cells. Lymphocytes residing in the spleen of the immune rats did not show cytotoxic activity against tumor cells but significant tumor lysis activity was recognized with TIL. This suggests that lymphocytes may achieve maturation after they leave the spleen. Cellular reactions occurring at the tumor site were enhanced at each step by various cytokines produced by lymphocytes as well as by inflammatory cells. This cytokine cascade seems to be essential for obtaining a sufficient immune response for tumor rejection. When an established T9 subcutaneous tumor with a diameter of 10 mm was treated by intratumoral infusion of lymphokine-activated killer (LAK) cells, the tumor showed complete regression after 2-3 weeks of transient growing.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

[Sarcoidosis].

Explore the source record for details and available documents.

Adolescent↗
PubMed1989

Magnetic resonance imaging of brain contusion.

In this study we investigated the time course of brain contusions using magnetic resonance imaging and compared the findings with those of a computed tomography scan. The lesions, which were demonstrated as homogeneous density areas on the computed tomography scan were demonstrated as different intensity areas in the magnetic resonance image. The intensity of the images varied according to the time at which the images were obtained. The findings indicated changes in the nature of the contusions including hematoma hemoglobin, perifocal edema extension, and so on. In conclusion, magnetic resonance imaging is important in the follow-up of chronological change as well as in original diagnosis of brain contusions.

Adolescent↗