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Biomedical subjects

A Okamoto

Publications and source records attributed to A Okamoto.

At least 199 records · Page 11Linked to original sources
PubMed1988

Analysis of T hybridomas prepared from a T cell clone with three specificities. Recognition of self + X and allo-H-2 determinants segregates from recognition of Mlsa determinants.

To see k information on T cell recognition of Mlsa determinants, hybridomas were prepared from a well-characterized F23.2+ (V beta 8.2+) T cell clone specific for three different ligands, i.e., 1) Mlsa determinants, 2) fowl gamma-globulin (F gamma G) plus self-H-2 (H-2d), and 3) allo-H-2, e.g., H-2p, determinants. Fusion of the clone to the BW5147 thymoma line produced a triple-reactive T hybridoma which generated two types of spontaneous variants. One type of variant (type I) lost Mlsa reactivity but retained reactivity to both F gamma G/H-2d and allo-H-2p. These variants, which were generated at high frequency, stained strongly with a mAb, A1.57, with idiotypic specificity for the TCR molecules of the parental clone. The second type of variant (type II) reacted to Mlsa determinants but showed no reactivity to F gamma G/H-2d or to allo-H-2p. These variants failed to express the A1.57 idiotypic determinants of the parent clone, but were F23.2+ (V beta 8.2+); nonequilibrium pH gradient electrophoresis analysis suggested that these hybrids expressed a mixed TCR heterodimer composed of the parental clone beta-chain and the BW5147 alpha-chain. Three aspects of the data are very difficult to accommodate with the view that Mlsa, F gamma G, and allo-H-2 determinants are all recognized via a common TCR molecule: 1) the independent (and frequent) segregation of Mlsa reactivity from F gamma G/H-2d and allo-H-2p reactivity, 2) the retention of Mlsa reactivity by the type II variants despite loss of the parental clone alpha-chain, and 3) the loss of Mlsa reactivity by the type I variants despite high expression of the A1.57+ TcR molecules derived from the parental clone. The data support a model in which Mlsa determinants are recognized by a separate T cell structure, which we envisage as a monomorphic accessory molecule unrelated to the TCR. Since the type II hybridoma variants invariably retained quantitatively normal TcR expression, the triggering phase of anti-Mlsa responses appears to be TCR dependent. The model we favor is that anti-Mlsa/Mlsa interaction increases TCR binding with Ia epitopes to above the threshold required for cell triggering. A key feature of this model is that Mlsa and Ia determinants are recognized as separate structures rather than as a complex.

Animals↗
PubMed1988

Secretion of soluble functional insulin receptors by transfected NIH3T3 cells.

In order to determine whether the human insulin receptor ectodomain can be expressed as a functional protein, the coding regions for the transmembrane and cytoplasmic domain of a full-length human insulin receptor cDNA were deleted by site-directed mutagenesis, and the resultant construct was inserted into a bovine papilloma virus vector under the control of the mouse metallothionein promoter. After transfection of mouse NIH3T3 cells, a cell line secreting an insulin binding protein was isolated. The insulin binding alpha subunit had an Mr of 138,000 and a beta subunit of Mr 48,000 (compared to 147,000 and 105,000 for the full-length human insulin receptor expressed in NIH3T3 cells). This difference in size of the alpha subunit was due to a difference in glycosylation as N-glycanase digestion reduced the apparent size of the alpha subunits of secreted and normal membrane-bound receptors to identical values. The secreted receptor formed disulfide-linked heterotetrameric structures with an Mr of 280,000. It was synthesized as an Mr 160,000 precursor which was cleaved into mature subunits with a t1/2 of 3 h. Increasing expression of the cDNA by induction with sodium butyrate lead to the appearance of an Mr 180,000 protein in the medium as well as the mature alpha and beta subunits. A Scatchard plot of insulin binding to the secreted receptor was curvilinear with a Kd of 7 X 10(-10) M for the high affinity sites and 10(-7) M for the low affinity site (compared to Kd values of 1.1 X 10(-9) M and 10(-7) M, respectively, for human insulin receptors expressed in these cells.

Animals↗
PubMed1988

Electrophysiologic diagnosis of cervical OPLL myelopathy using evoked spinal cord potentials.

The purpose of this study is to establish the correct diagnosis of the location and extent of intraspinal cord lesions in cases of continuous or mixed-type ossification of the posterior longitudinal ligament and to estimate the postoperative prognosis using evoked spinal cord potentials (ESCP). Twenty-six patients, who underwent surgery from 1985 to 1987 and who have been followed for more than 6 months, were examined using a conductive ESCP, which demonstrates lower extremity, bowel, and bladder function, and a segmental ESCP and dermatome segmental ESCP, which demonstrate upper extremity function. A five-pole recording electrode was placed in the cervical epidural space. The stimulation sites were the thoracic epidural space for conductive ESCP, the median nerve at the elbow for the segmental ESCP, and the finger surface for the dermatome segmental ESCP. In cases in which the ESCP disappeared at the middle of the narrow cervical spinal canal, another stimulating electrode was placed in the cisterna magna, and a descending conductive ESCP was recorded to monitor the upper border of the spinal lesion. New findings, which could not be observed by roentgenograms, myelography, and CT scan, were detectable using this technique.

Aged↗
PubMed1988

Effect of intraoperative radiotherapy on pancreatic carcinoma: histopathological findings from autopsy cases.

Histopathological examinations of 18 necropsy patients with pancreatic carcinoma who died after receiving intraoperative radiotherapy (IOR) revealed the following: 1) Cancer cells were suspected of remaining in the periphery of the irradiated areas. 2) Thickening of intima of small arteries, some of which were obstructed, was found in the tumor tissues. 3) Highly degenerated nerve fibers were observed within the necrotic or viable tumor tissues. These findings provide evidence of the effects of IOR, while they also demonstrate the problems encountered in improving this treatment and the necessity of a complementary therapy for complete local control of pancreatic cancer by IOR.

Adult↗
PubMed1988

Carcinoma of the ampulla of Vater: expression of cancer-associated antigens inversely correlated with prognosis.

To obtain some useful pathologic indicators for predicting the prognosis in carcinomas of the ampulla of Vater, we analyzed 24 surgically resected ampullary carcinomas pathologically with immunohistochemistry of cancer-associated antigens. Pancreatic invasion, lymph node metastasis, and histology of the tumor were significantly correlated with poor prognosis (p less than 0.01), but the size or ulceration of the tumor did not significantly affect the prognosis (p less than 0.05). Immunohistochemically, diffuse positivity for anti-CA19-9 monoclonal antibody was demonstrated in 10 carcinomas and that for anti-carcinoembryonic antigen (CEA), in 10. Eight of them showed synchronously diffuse immunoreactivities for both antigens. Although there was no significant correlation between diffuse positivity for CA19-9 and pathologic factors, CA19-9-positive cases exhibited significantly poor prognoses (p less than 0.01). Diffuse positivity for CEA was correlated with pancreatic invasion (p less than 0.05) and poor prognosis (p less than 0.05). Immunohistochemical study of cancer-associated antigens may disclose some malignant potential of ampullary carcinoma other than that expressed in the morphology. Furthermore, because of the consistency of staining results, immunohistochemistry of cancer-associated antigens may also be useful in predicting preoperatively the prognosis of ampullary carcinoma in biopsied materials.

Actuarial Analysis↗
PubMed1988

Tumoricidal activity of lymphotoxin (tumor necrosis factor beta) in vivo: its effects on macrophages.

We investigated the cytotoxic activity of recombinant human lymphotoxin (rHuLT) against Meth A sarcoma in vitro and in vivo. In direct cytotoxic assay, Meth A cells showed very low, if any, sensitivity to rHuLT. However, rHuLT was found to be strongly cytotoxic for subcutaneously implanted Meth A cells. In order to explain this discrepancy, we examined the indirect effects of rHuLT on Meth A cells particularly through macrophages. rHuLT showed macrophage chemotactic activity in vitro and also in vivo. Thus, injection of rHuLT into the mouse peritoneal cavity caused migration of macrophages to the peritoneal cavity. In addition, histologic analysis revealed that 6 h after intratumor injection of rHuLT, nonspecific esterase-positive cells started to migrate into Meth A tumor tissues, and after a further 24 h, a larger number of nonspecific esterase-positive cells had migrated into the Meth A tumor tissues. Moreover, peritoneal exudate cells induced by rHuLT showed considerably higher cytotoxic activity against Meth A cells than proteose peptone- or phosphate-buffered saline-induced peritoneal exudate cells. Furthermore, the cytotoxic activity of peritoneal exudate cells was found to reside in macrophages. Investigation of the mechanism of macrophage activation by rHuLT revealed that rHuLT can activate macrophages for cytotoxicity synergistically with mouse interferon-gamma. These results strongly suggest that rHuLT, when injected into the tumor, can induce the migration of macrophages into the tumor and activate macrophages in situ to kill tumor cells.

Animals↗
PubMed1988

[A case of non-jaundice ampullary carcinoma with prominent lymphatic infiltration].

A case of a non-jaundiced ampullary carcinoma with a unique tumor spread is reported. A 3.2 X 1.0 cm-sized tumor at the ampulla of Vater was resected in a 64-year-old female. The primary focus of the well differentiated adenocarcinoma was confined to the intraampullary common channel, but the most of the tumor consisted of lymphatic permeation. A wide spread lymphogenous metastases had been noticed at operation, and the patient died nine months thereafter from metastases of the brain. The mechanism which prevented jaundice from developing in this case might be due to the unique way in which this tumor spread, without obstruction via the lymphatic space and only stenosing the bile duct.

Adenocarcinoma↗
PubMed1987

Identification of new C27 and C24 bile acids in the bile of Alligator mississippiensis.

Biliary bile acids of Alligator mississippiensis were analyzed by gas-liquid chromatography-mass spectrometry after fractionation by silica gel column chromatography. It was shown that the alligator bile contained 12 C27 bile acids and 8 C24 bile acids. In addition to the C27 bile acids, such as 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha-cholestanoic acid, 3 alpha,7 alpha-dihydroxy-5 beta-cholestanoic acid, 3 alpha,12 alpha-dihydroxy-5 beta-cholestanoic acid, 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholestanoic acid, and 3 alpha,12 alpha-dihydroxy-7-oxo-5 beta-cholestanoic acid, identified previously in the bile of A. mississippiensis, 3 alpha,7 beta-dihydroxy-5 beta-cholestanoic acid, 3 alpha,7 beta,12 alpha-trihydroxy-5 beta-cholestanoic acid, 7 beta,12 alpha-dihydroxy-3-oxo-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 beta-cholestanoic acid, and 1 beta,3 alpha,7 alpha,12 alpha-tetrahydroxy-5 beta-cholestanoic acid were newly identified. And in addition to the C24 bile acids, such as chenodeoxycholic acid, ursodeoxycholic acid, cholic acid, and allocholic acid, identified previously, deoxycholic acid, 3 alpha,7 alpha-dihydroxy-5 beta-chol-22-enoic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha-chol-22-enoic acid, and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-chol-22-enoic acid were newly identified.

Alligators and Crocodiles↗
PubMed1987

So-called "papillary and cystic neoplasm of the pancreas." An immunohistochemical and ultrastructural study.

A case of so-called "papillary and cystic neoplasm of the pancreas" (PCNP) was reported and investigated immunohistochemically and ultrastructurally. A tumor of the pancreatic head in a 21-year-old female was curatively resected. The tumor was cystic and histologically consisted of uniform cells in papillary and solid structure. Although there was no immunoreactivity for pancreaticogut hormones or secretory products of the pancreas in the tumor cells, most of the tumor cells were diffusely immunoreactive for neuron-specific enolase (NSE). Some neurosecretory granules were detected in the tumor cells ultrastructurally. Both facts suggested endocrine cell character of the tumor. Certain cases of PCNP might show a differentiation to endocrine cells.

Adult↗
PubMed1987

[Considerations on intraoperative radiation therapy and therapeutic ratio].

In conjunction with the clinical development of intraoperative radiation therapy (IORT), the ability to demonstrate an improvement in therapeutic ratio is critical and an evaluation of treatment complications is essential. The tolerance dose of the normal tissue in IORT is discussed, and if small field is applied, the greater part of tissues or organs tolerate intraoperative irradiations up to 25 Gy. The optimal dose has been estimated on each organs with malignant tumors. Intraoperative "boost" dose electron therapy given in combination with external beam irradiation has been demonstrated as good treatment modalities concerning with therapeutic ratio.

Brain Neoplasms↗
PubMed1987

A case of malignant cystic endocrine tumor of the pancreas.

A malignant pancreatic endocrine tumor with a cystic appearance in a 66-yr-old woman was reported. Total pancreatectomy was performed under the diagnosis of cystadenocarcinoma. The tumor was large and cystic, but the solid portion of the tumor showed histologically a ribbon-like array of small uniform cells typical for endocrine tumors. Immunohistochemically, most tumor cells were immunoreactive for neuron-specific enolase, chromogranin, and Leu 7-epitope. Ultrastructurally, innumerable neurosecretory granules were demonstrated in the cytoplasm of most tumor cells. The patient survived for 5.5 yr after operation despite liver metastases, some of which also showed cystic appearances.

Aged↗
PubMed1986

Non-restraining factors affecting setting expansion of phosphate-bonded investments.

Only a few studies on the setting expansion of phosphate-bonded investments have been published. In the present work the effect on the non-restrained setting expansion of mixing time, mixing liquid, mixing device, and volume mixed was investigated for selected brands of this type of investment. It was found that all variables studied may greatly affect the setting expansion, and that the use of the special liquid delivered by the manufacturers in most cases causes an unacceptably high expansion. A modification of the brands studied appears necessary before they can be employed in a precision-requiring technique.

Chemical Phenomena↗
PubMed1986

Restraining factors affecting setting expansion of phosphate-bonded investments.

The effects of several factors on the setting expansion of a phosphate-bonded investment used in a steel casting ring were studied. The results show that the setting expansion under the conditions analyzed can be characterized only as a most unreliable means to partly compensate for the solid thermal contraction of casting alloys in a precision-requiring technique.

Chemical Phenomena↗
PubMed1986

[Postoperative nutritional assessment in gastric and colorectal cancer].

From the 200 malnutritional cancer patients, we had obtained, so called, prognostic nutritional index (PNI): PNI = 10 X Alb. + 0.005 Lymph. C., where Alb. is serum albumin level (g/dl) and Lymph. C. is total lymphocytes count of peripheral blood level. This index, as we had reported, shows linear predictive model correlating the risk of operative complication, mortality or both with nutritional status. In this study, we report on the utility of the PNI as a nutritional index (NI) for postoperative patients. The subjects of this study were 22 gastric cancer patients (G group), performed total gastrectomy or proximal gastrectomy, and 18 colorectal cancer patients (C group), underwent colectomy or rectal resection and anastomosis but amputation. All these cases underwent nutritional support by TPN postoperatively. The values of NI of both groups were the lowest at the first postoperative day, and increased gradually to the seventh postoperative day. And the value of C group was higher than that of G group throughout the TPN period: From the first postoperative day to the 14th day. These results reflected the result obtained from the estimation of nitrogen balance, urinary 3-methylhistidine excretion and serum rapid turnover protein (transferrin, prealbumin and retinol binding protein). These results suggest that the NI is useful to estimate the improvement of the postoperative nutritional status.

Adult↗