Biomedical subjects

T Endo

Publications and source records attributed to T Endo.

At least 523 records · Page 29Linked to original sources

PubMed1995

Mitochondrial presequences can induce aggregation of unfolded proteins.

We have studied the interactions between various synthetic peptides and two model unfolded proteins, reduced alpha-lactalbumin and reduced and carboxymethylated alpha-lactalbumin. We found that mitochondrial presequences could induce aggregation of the unfolded alpha-lactalbumins but not of the native alpha-lactalbumin. The presequence-induced aggregation of unfolded alpha-lactalbumin was dependent on electrostatic interactions and on the amphiphilicity of the presequences. Since positive charge and amphiphilicity are necessary for the targeting function of mitochondrial presequences, presequence-induced aggregation may be responsible for the instability of mitochondrial precursor proteins and may need to be inhibited by binding factors in the cytosol.

Amino Acid Sequence↗

PubMed1995

Identification of yeast MAS17 encoding the functional counterpart of the mitochondrial receptor complex protein MOM22 of Neurospora crassa.

MOM22 of Neurospora crassa was suggested to be required for the transfer of mitochondrial precursor proteins from the receptors to the protein translocation machinery. We isolated a yeast mutant the viability of which depended on the expression of the introduced N. crassa MOM22 gene. The mutant cells showed defects in protein import into mitochondria when the cells were depleted of MOM22. By screening for suppressor genes for the mutant, we could identify the yeast gene MAS17 encoding the functional counterpart of MOM22. The MAS17 gene was found to be essential for the viability of yeast cells.

Amino Acid Sequence↗

PubMed1995

Intracaval ultrasonography in the diagnosis of tumour involvement of the vena cava.

A retrospective study of 34 consecutive patients with possible tumour involvement of the vena cava was performed to assess the usefulness of intracaval ultrasonography. Twenty-five of the 34 patients were operated and resection carried out in 23, including seven with combined resection of the vena cava. The sonographic criterion for vena cava invasion was obliteration of the echogenic ring of the vena cava wall or intracaval tumour mass. The sensitivity, specificity and overall accuracy of intracaval endovascular ultrasonography in the diagnosis of tumour involvement of the vena cava were 100, 96 and 97 per cent respectively. The respective values were 91, 61 and 71 per cent for computed tomography and 82, 67 and 72 per cent for cavography. Ultrasonography is a useful technique that can precisely evaluate the vena cava for possible tumour invasion, especially when the presence or extent of tumour involvement is not definitely established by conventional imaging techniques.

Adult↗

PubMed1995

Preoperative intra-aortic ultrasonography to determine resectability in advanced oesophageal cancer.

This study was designed to evaluate the effectiveness of intra-aortic ultrasonography in the preoperative diagnosis of aortic wall invasion by oesophageal cancer. Twenty-four patients with advanced oesophageal cancer underwent the procedure, and aortic invasion was found in seven. In three of these seven patients, the invasion was diagnosed to be limited to the aortic adventitia, enabling preoperative prediction of the resectability of the tumour. The contact angle of the tumour in relation to the descending aorta was more than 90 degrees in six patients, and aortic invasion to all layers was visualized in four by intra-aortic ultrasonography. On the other hand, aortic invasion to the adventitia was found in three of 14 patients in whom the contact angle was less than 90 degrees. Intra-aortic ultrasonography provides important information to help determine the resectability of advanced oesophageal cancer.

Adult↗

PubMed1995

Mercury uptake by primary cultures of rat renal cortical epithelial cells. I. Effects of cell density, temperature, and metabolic inhibitors.

Factors affecting the renal uptake of inorganic mercury were investigated using primary cultures of rat renal cortical epithelial (RCE) cells under protein- and amino acid-free conditions. The cells were isolated from kidneys of adult rats and cultured. Confluence of culture (cell density), monitored morphologically and by total protein content, was achieved on Day 5. The RCE cells were incubated with 1 microM Hg at 37 degrees C for 30 min, followed by washing with phosphate-buffered saline containing various chelating agents (i.e., EGTA, PEN, DMSA, and BAL) to remove the surface-bound, noninternalized Hg. A substantial portion of Hg was bound to the cell surface. The removal of Hg from these binding sites was dependent on the stability constants of the chelating agents for Hg and lipophilic BAL removed the most Hg. Hg accumulation by the cells was dependent on cell density and decreased as the cell culture became confluent, possibly due to the formation of tight junctions resulting in a majority of the Hg transport occurring through the apical membrane. As measured after BAL washing, metabolic inhibitors, NaF, DNP, and ouabain decreased Hg accumulation by 28% and low temperature (4 degrees C) decreased it by 62%. Dependence of Hg uptake on metabolic energy and temperature suggests that a part of Hg is transported via active transport system. The pronounced decrease of Hg uptake at 4 degrees C indicates that, in addition to active transport, Hg transport also involves simple diffusion, some of which is dependent on membrane fluidity. It is concluded that Hg transport in RCE cells through the apical membrane occurs mainly by diffusion, and to a smaller extent by active transport.

Animals↗

PubMed1995

Mercury uptake by primary cultures of rat renal cortical epithelial cells. II. Effects of pH, halide ions, and alkali metal ions.

The effects of pH, halide ions, and alkali metal ions on the uptake of inorganic mercury (Hg) were investigated in confluent primary cultures of rat renal cortical epithelial cells. The cells were incubated with 1 microM Hg in phosphate buffer at pH 5.5, 6.4, or 7.4 for 30 min at 37 degrees C. Incubation of cells at pH 5.5 resulted in a 22% increase in total Hg accumulation over those cells that were incubated at pH 7.4. Almost all of this increase was accounted for in the membrane fraction. In contrast, there was a 33% reduction in internalized Hg in cells incubated at pH 5.5. This may be explained by the conversion of hydroxide forms of Hg (Hg(OH)Cl and Hg(OH)2) to the chloride forms (HgCl2, HgCl3-, and HgCl4(2-) at a lower pH (decreased OH-) condition. In the presence of halide ions, the cells internalized Hg in the relative order of affinity of the halide ions for Hg2+ (i.e., F- < Cl- < Br- < I-). Br- and I- resulted in a 67 and 142% increase in internalized Hg over that by Cl-. The relatively high membrane binding and internalization of Hg in the presence of Br- and I- was possibly due to the formation of highly lipophilic complexes of Hg (i.e., HgBr2 and HgI2). The replacement of NaCl in the incubation medium by KCl caused a 36% decrease in internalized Hg. LiCl had a similar effect on the internalization of Hg. The above results suggest that in rat renal proximal tubules Hg uptake involves Na(+)- and H(+)-dependent mechanisms.

Animals↗

PubMed1995

Acanthamoeba sp. from the Philippines: electron microscopy studies on naturally occurring bacterial symbionts.

The isolation of two plasmid-like circular DNAs, measuring 52 and 42 kbp, from an Acanthamoeba sp. from the Philippines has led to the demonstration of a bacterial endosymbiont occurring in this free-living amoeba. The 52-kbp band hybridized with a short sequence of cytochrome b gene and was identified as the mitochondrial DNA, whereas the 42-kbp band was identified as plasmid DNA of the bacterial symbionts on the basis of electron microscopy. The endosymbionts are gram-negative, rod-shaped bacteria measuring approximately 1.3 x 0.43 microns and numbering about eight to ten cells per section. They are randomly distributed in both cysts and trophozoites and are surrounded neither by a phagolysosomal membrane nor by a clear or electron-translucent region. The endosymbiont membrane appears to have a close association with ribosomes, which are seen to be more concentrated within the vicinity of the symbionts than elsewhere within the cytoplasm. Attempts to grow the symbionts and the amoebae separately have failed.

Acanthamoeba↗

PubMed1995

Diagnostic usefulness of chest computed radiography--film versus cathode-ray tube images.

Seventy-one plain chest images obtained by computed radiography (CR) with an imaging plate were interpreted on film and two kinds of cathode-ray tube (CRT) monitors installed separately at two facilities (1,024 x 1,536 pixels, 8 bits, and 1,024 x 1,280 pixels, 10 bits) by 20 radiologists and four chest internists. The clinical categories of these 71 cases included pulmonary nodules and interstitial abnormalities. Image reading sessions were held over a total of 4 days, ie, 2 days and then another 2 days, 3 weeks later. Twenty-four observers formed four groups with six members each. Two groups read either films or CRT images at one of the two facilities. In the second experiment, 26 of 71 images were compressed at 10:1, 19 of 71 were compressed at 20:1, and 26 were not compressed. Analyses of the areas under the receiver-operating characteristic curves showed no significant differences in detection of pulmonary abnormalities between film and CRT. In detecting interstitial pulmonary abnormalities, film was more sensitive than CRT monitor. There were no significant differences in observers' performances between the two different kinds of CRT workstation. Subjective evaluation of image quality showed that images irreversibly compressed to the ratios of 10:1 and 20:1 were inferior to original images. Although further considerations are needed with regard to spatial resolution requirements, image processing, and image compression, the utilization of CR CRT image as a substitute for CR film image will be possible.

Data Display↗

PubMed1995

Keloid formation after surgery for release of polysyndactyly of the feet in a child.

Keloid formation on the hands and the feet is very rare but should always be anticipated as a possible complication after surgery. Failure to recognise the potential for keloid may result in a severe deformity that is functionally and cosmetically undesirable. We report severe keloid formation after simple release of polysyndactyly of the feet of a 2-year-old child.

Female↗

PubMed1995

Activation of phospholipase D by prostaglandin F2 alpha in rat luteal cells and effects of inhibitors of arachidonic acid metabolism.

In rat luteal cells labeled with [3H]oleic acid, PGF2 alpha-stimulated phospholipase D (PLD) activation was investigated. The PLD activity was detected by measuring the accumulation of [3H]phosphatidylethanol (PtdEt) in the presence of ethanol. PGF2 alpha stimulated PtdEt accumulation at concentrations of more than 100 nM in the presence of ethanol. However, PtdEt accumulation did not change in the absence of ethanol. PGF2 alpha (1 microM) increased PtdEt accumulation after 1 min, and the accumulation reached a plateau by 2-3 min. These results indicate that PGF2 alpha activates PLD in rat luteal cells. U-73122, a phospholipase C (PLC) inhibitor, and staurosporine, a protein kinase C (PKC) inhibitor, did not inhibit PGF2 alpha-stimulated [3H]PtdEt accumulation. These results suggest that PGF2 alpha-induced PLD activation is different from PLC-PKC systems. We reported previously that PGF2 alpha stimulated the release of arachidonic acid. The effects of indomethacin, nordihydroguaiaretic acid (NDGA), and 5,8,11,14-eicosatetraynoic acid (ETYA), inhibitors of arachidonic acid metabolism, on PGF2 alpha-stimulated PtdEt accumulation were examined. Pretreatment with indomethacin enhanced PGF2 alpha-induced PtdEt accumulation. In contrast, pretreatment with NDGA and ETYA inhibited PGF2 alpha-induced PtdEt accumulation. It is suggested that PGF2 alpha-stimulated PLD activation is mediated via lipoxygenase products.

5,8,11,14-Eicosatetraynoic Acid↗

PubMed1995

Glycosylation of the variable region of immunoglobulin G--site specific maturation of the sugar chains.

The structure of the N-linked sugar chains attached to three IgG antibodies, identical in amino acid sequence except for the changes required to introduce the carbohydrate addition sites, has been determined. All three antibodies are specific for dextran but differ in their ability to bind antigen. The heavy chains with a murine variable region (V region) attached to the human gamma 4 constant region were expressed in a murine hybridoma synthesizing the specific light chain. In addition to the glycosylation site in the Fc portion, each antibody has a different glycosylation site in the second complementarity determining region (CDR2) of the heavy chain (Asn54, Asn58, or Asn60). The sugar chains were released from purified Fab and Fc fragments by hydrazinolysis and converted to radioactive oligosaccharides by reduction with sodium borotritide. The structures of these radioactive oligosaccharides were determined by a combination of sequential exoglycosidase digestion and Bio-Gel P-4 and lectin column chromatography. For all three antibodies, the carbohydrate attached to the Fc portion was a mixture of complex-type biantennary sugar chains. The variable region carbohydrate structures attached at Asn54 and Asn58 were also complex-type but more highly sialylated than were the Fc-associated sugars. Moreover, unlike the Fc-associated sugars, a significant population of Fab-associated sugars contained a Gal alpha 1-->3 residue as a non-reducing terminus. In contrast, the carbohydrate attached at Asn60 was a high mannose structure. These results demonstrate that slight changes in the position of carbohydrate attachment within CDR2 of the variable region of the heavy chain can substantially alter carbohydrate processing and that complex-type carbohydrates contained within the same polypeptide chain can have different structures.

Amino Acid Sequence↗

PubMed1995

Intraarterial infusion of dibutyryl cyclic adenosine monophosphate plus mitomycin C for unresectable hepatocellular carcinoma: long-term survival and response to tumor growth inhibition.

RATIONALE AND OBJECTIVES: Dibutyryl cyclic adenosine 3',5'-monophosphate (dBcAMP) has the capacity to promote morphologic differentiation and to inhibit tumor growth in vitro, but it has not been well researched in the clinical setting. In this study we examined the effects of intraarterial infusion of dBcAMP plus mitomycin C (MMC) on long-term survival and growth inhibition of tumors. METHODS: Thirty-one previously untreated patients with unresectable hepatocellular carcinoma (HCC) received intraarterial infusion of dBcAMP plus MMC. According to the International Union Against Cancer staging system, three patients had stage T3, eight had stage T4a, and 20 had stage T4b cancer. Growth inhibition was defined as no computed tomography (CT) scan evidence of increase in tumor diameter for at least 6 months after treatment. RESULTS: In all 31 patients with HCC, the cumulative survival rate was 34% at 1 year, 14% at 3 years, and 9% at 5 years. The median survival was 5.0 months, with the longest survival period being 92 months. Among 21 patients in whom a tumor response could be evaluated on the basis of follow-up CT studies, two had complete regression of their primary tumors. Overall, the response rate was 43% (9 of 21). Among the 12 stage T4b patients who had HCC that included the main trunk and its major branches of the portal vein, portal thrombi had disappeared in four (33%). Among eight patients who survived more than 1 year and were evaluated for tumor response using follow-up CT scan studies, six (75%) had growth inhibition of tumor. CONCLUSION: Chemotherapy combined with dBcAMP and MMC showed a favorable response in approximately one third of 31 patients who had unresectable HCC. Because of our results, combined therapy should be strongly considered in the treatment of patients with HCC including occlusion of the main portal vein.

Antibiotics, Antineoplastic↗

PubMed1995

The functional significance of the second extracellular loop of thyrotropin receptor in thyrotropin- and thyroid stimulating antibody-dependent signal transduction.

In order to determine the functional significance of the extracellular loop of human thyrotropin receptor (hTSHR), two peptides composed of eight amino acids were inserted into hTSHR by ligating synthetic oligonucleotides into +1811 NCol site of hTSHR cDNA. Mutant hTSHR cDNAs which encode a hydrophobic peptide (ATVLVVPM) and a hydrophilic peptide (GTTRTVAM) between +572 Met and +573 Asp were transfected into Chinese hamster ovary (CHO) cells to develop F-cell lines and R-cell lines, respectively. Of the resulting cloned cell lines, F-29 and R-9 were shown to express mutant hTSHs at the protein level by Western blotting and at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR). We show that neither thyrotropin (TSH) nor IgGs from patients with Graves' disease stimulated cAMP production by F-29 and R-9 cells. 125I-TSH binding study revealed that F-29 and R-9 cells do not bind TSH. Our data demonstrate that the mutations impaired TSH-binding and incapacitated the cells from responding to TSH. The evidence suggests that the second extracellular loop of hTSHR has an important role in TSH and thyroid stimulating antibody (TSAb)-dependent signal transduction.

Amino Acid Sequence↗

PubMed1995

Point mutations in the thyrotropin receptor in human thyroid tumors.

The mechanism of the impaired response to thyrotropin (TSH) in thyroid tumor cells was investigated by searching for structural changes in the TSH receptor (TSH-R) in neoplastic thyroid tissues in humans. Total RNA was prepared from 34 thyroid tissue samples (four normal, six adenoma, six follicular cancer, and 18 papillary cancer) and reverse- transcribed into single-stranded cDNA, which was then used as a template for the polymerase chain reaction and subjected to single-strand conformation polymorphism (SSCP) analysis. Two fragments, FRAG (468-692) (nucleotides 468 to 692, corresponding to the mid-portion of the receptor extracellular domain) and FRAG (2044-2295) (nucleotides 2044 to 2295, corresponding to the COOH-terminal, cytoplasmic domain of the TSH-R cDNA) showed differences in electrophoretic mobility among the various thyroid tissue samples. Direct sequencing revealed Phe197 (TTC) --> Ile(ATC), and Asp219 (GAT) --> Glu(GAG) substitutions in FRAG (468-692) from two papillary cancers. Three types of substitution were identified in FRAG(2044-2295): Asn715 (AAC) --> Asp(GAC) from one papillary cancer, Lys723 (AAG) --> Met(ATG) from one papillary cancer, and Asp 727 (GAC) --> Glu(GAG) from one normal tissue sample, one follicular cancer, and four papillary cancers. These results suggest that there exist structural changes in TSH-R in some cases of thyroid neoplastic tissue.

Adenoma↗

PubMed1995

Avidin fusion protein as a tool to generate a stable translocation intermediate spanning the mitochondrial membranes.

We have designed a fusion gene encoding a chimeric mitochondrial precursor protein (avidin fusion protein) that consists of the mitochondrial presequence followed by mouse dihydrofolate reductase, a spacer segment, and streptavidin. The avidin fusion protein synthesized in vitro formed a tetramer at the avidin moiety on incubation with biotin during or after the translation reaction. The avidin fusion protein purified from the Escherichia coli overexpresser cells also formed the tetramer on dilution from 6M urea into buffer containing biotin. In in vitro import experiments with isolated yeast mitochondria, the tetramer of the avidin fusion protein became stuck across both mitochondrial membranes, with its N-terminal dihydrofolate reductase moiety in the matrix and its C-terminal avidin moiety exposed on the mitochondrial surface. Accumulation of the translocation intermediate of the fusion protein inhibited the import of a mitochondrial precursor protein, and allowed us to estimate the number of mitochondrial import sites.

Animals↗

PubMed1995

Cyclic change in 3 alpha-hydroxysteroid dehydrogenase in rat ovary during the estrous cycle.

3 alpha-Hydroxysteroid dehydrogenase (3 alpha-HSD) activity and content in the rat ovary were measured at various stages of the estrous cycle, and the enzyme protein in the ovary was localized by immunohistochemistry. The cyclic change of ovarian 3 alpha-HSD activity towards 5 alpha-dihydrotestosterone (5 alpha-DHT) as a substrate was characterized by two peaks. The first peak occurred at 0800 h on proestrus; then the reductase activity decreased and reached its minimum at 2000 h on proestrus. Thereafter, it gradually increased, reaching the second peak (170% of the value at 2000 h on proestrus) at noon of estrus. Quantitative analysis by immunoblotting revealed that the alteration in 3 alpha-HSD content in the rat ovary during the estrous cycle was essentially similar to that in 5 alpha-DHT reductase activity. Changes in the reductase activities towards 5 alpha-androstane-3,17-dione and 5 alpha-DHT and in the dehydrogenase activity towards androsterone in the ovary were entirely different from those in the 5 alpha-DHT reductase activity and 3 alpha-HSD content; on the other hand, the change in carbonyl reductase activity towards p-nitroacetophenone was similar to changes in 5 alpha-DHT reductase activity and 3 alpha-HSD content. Therefore, p-nitroacetophenone may be a useful substrate, instead of 5 alpha-DHT, for detection of 3 alpha-HSD activity at a high sensitivity, since the p-nitroacetophenone reductase activity was 10-fold higher than the 5 alpha-DHT reductase activity. The enzyme was primarily localized in the granulosa cells and CL cells. At 2000 h on proestrus, however, the overall intensity of immunostaining in the granulosa cells of the Graafian follicles was markedly diminished. In addition, immunoreactivity in the CL cells at 0800 h on estrus was observed only in the cells outlining the CL in some cases.

3-Hydroxysteroid Dehydrogenases↗

PubMed1995

Intraportal endovascular ultrasonography in the diagnosis of portal vein invasion by pancreatobiliary carcinoma.

OBJECTIVE: The purpose of this study was to determine the value of intraportal endovascular ultrasonography (IPEUS) in the diagnosis of portal vein invasion by pancreatobiliary carcinoma. The authors reported their experiences with this new technique and compared it with conventional imaging technologies, such as portography and computed tomography (CT). SUMMARY BACKGROUND DATA: Pancreatobiliary carcinoma often invades the portal vein. Observation of the echogenic band of the portal vein wall by means of a high-frequency, high-resolution intravascular ultrasound catheter allows for the accurate diagnosis of the portal vein invasion. METHODS: A prospective study of 30 consecutive patients with pancreatobiliary carcinoma (16 pancreatic carcinomas, 8 bile duct carcinomas and 6 gallbladder carcinomas) was performed. In 23 cases IPEUS was performed intraoperatively from the superior mesenteric venous route with an 8 French, 20 MHz intravascular ultrasound catheter. In 7 cases IPEUS was performed before surgery from the percutaneous transhepatic route with a 6 French, 20 MHz intravascular ultrasound catheter. The finding of IPEUS was confirmed by pathologic examination of resected specimens and surgical exploration. The results of IPEUS were compared to those of portography and CT. RESULTS: Intraportal endovascular ultrasonography visualized the portal vein wall as an echogenic band with a thickness of 0.5 mm to 1.0 mm. The diagnostic criterion of portal vein invasion was destruction of this echogenic band. Portal vein invasion was found in 15 of 30 cases. Vascular invasion was confirmed by pathologic examination of resected specimens in 10 patients and operative findings in 5. The sensitivity, specificity, and overall accuracy of IPEUS for diagnosis of portal vein invasion was 100%, 93.3%, and 96.7%, respectively. The values were 80%, 67.7%, and 73.3% for portography and 53.3%, 80%, and 66.7%, respectively, for CT. CONCLUSIONS: Intraportal endovascular ultrasonography provided precise information about the relationship between the pancreatobiliary tumor and the portal vein wall. It was capable of accurately detecting or excluding early invasion of the portal vein wall by pancreatobiliary carcinoma.

Aged↗

PubMed1995

V2 receptor-mediated vasodilation in healthy humans.

Arginine vasopressin (AVP) causes biphasic changes in vascular resistance in human forearms: vasoconstriction at lower doses and vasodilation at higher doses. Vasoconstriction is mediated by the V1 receptor, but the mechanism of AVP-induced vasodilation remains unclear. To determine if the AVP-induced vasodilation in human forearm vessels is mediated by the V2 receptor, we examined the effects of OPC-31260 (a novel vasopressin V2 receptor antagonist) on AVP-induced vasodilation. The brachial artery was cannulated for drug infusions and direct measurement of arterial blood pressure (BP). We measured forearm blood flow (FBF) by a strain-gauge plethysmograph and calculated forearm vascular resistance (FVR). AVP was infused intraarterially (i.a.) at doses of 0.1, 0.2, 0.5, 1.0, and 2.0 ng/kg/min (n = 8). The lower dose of AVP (0.1 ng/kg/min) increased, whereas the higher doses of AVP (> or = 0.5 ng/kg/min) decreased, FVR (p < 0.01). Infusion of nitroglycerin (NTG) i.v. doses of 1.7, 3.3, and 10.0 ng/kg/min decreased FVR dose dependently (p < 0.01). OPC-31260 (1.0 micrograms/kg/min) infused i.a. did not alter arterial BP, baseline FVR, or heart rate (HR). OPC-31260 did not affect AVP-induced vasoconstriction but blocked AVP-induced vasodilation completely. OPC-31260 did not affect NTG-induced vasodilation. These results suggest that AVP-induced vasodilation is mediated by the V2 receptor in human forearm resistance vessels.

Adult↗