Biomedical subjects
Publications and source records attributed to M Sakaguchi.
The components responsible for protein translocation across the endoplasmic reticulum membrane have been identified and their functions have been clarified in vitro. The structural features of the signal peptide specify the factors and pathways of membrane translocation. Various chaperones and folding enzymes are involved in the folding and quality control of secretory proteins in the lumen.
The BC-1 strain DNA of Marek's disease virus type 1 (MDV1) at high-passage in culture was found to contain tandem direct repeats of the complete long terminal repeat (LTR) sequence of avian leukosis virus RAV0 strain as the repeat unit within the short inverted repeats of the MDV1 DNA. Since the attenuated BC-1 strain grows well in cultured cells, the insertion site for retroviral DNA sequence within the short inverted repeat of MDV1 DNA is not essential for viral growth in culture.
BACKGROUND: The tsBN7 cell line is one of the temperature-sensitive mutants for cell proliferation which have been isolated from the BHK21 cell line derived from the golden hamster. It has a mutation in the DAD1 gene encoding a 12.5kDa highly conserved protein through evolution, and enters apoptosis at the restrictive temperature due to this mutation. RESULTS: DAD1 was recovered in light membrane fractions after differential centrifugation. It could not be released from the membrane, even by carbonate extraction, without a detergent. Upon digestion with proteinase K, both N and C terminal portions-but not the middle portions of DAD1- were released from the membrane. Thus, DAD1 appears to be an integral membrane protein in which both termini are located in the cytosol. DAD1 was localized in the endoplasmic reticulum. In accordance with a similarity to the yeast protein Ost2p, which is a subunit of the oligosaccharyltransferase, at the restrictive temperature, loss of DAD1 function caused a defect of N-linked glycosylation in tsBN7 cells resulting in apoptosis. However, tunicamycin, which is known to inhibit N-linked glycosylation did not induce apoptosis in either tsBN7 or BHK21 cells. CONCLUSION: tsBN7 cells have a defect in N-linked glycosylation caused by the loss of DAD1.
Japanese cedar (Cryptomeria japonica) pollinosis has been reported to occur naturally in Japanese monkeys (Macaca fuscata) as well as humans. Using monoclonal antibodies (mAb) specific to Cry j 1, a major allergen in Japanese cedar pollen, we identified five independent epitopes (EP-1 to EP-5) on the molecule. The epitopes recognized by IgE antibodies in the sera of humans and monkeys with the pollinosis were analysed by an IgE enzyme-linked immunosorbent assay inhibition method with these mAb. In human patients, the mAb to EP-1 strongly blocked the binding of IgE antibodies in all patients' sera to Cry j 1. The reaction patterns of IgE antibodies in monkeys, however, varied among the troops of monkeys. In some troops, the mAb to EP-1 showed a blocking pattern similar to that for human patients. In other troops, mAb to EP-4 and EP-5 blocked binding of IgE. These results indicate that some, but not all, monkeys have antibody responses to the major allergen similar to those of humans.
Two distinct insulin-like growth factor-I (IGF-I) cDNAs were isolated from a juvenile carp liver cDNA library. Both of the cDNAs encoded a full length prepro IGF-I with 161 amino acids: a mature peptide (70 residues), its signal peptide (44 residues), and a carboxy-terminal E domain (47 residues). The similarity of the two cDNA in the open reading frame was 95.1%. The amino acid sequences of E domain predicted by the two cDNAs were different while those of the signal peptide and the mature peptide were the same. By Northern blot analysis, four different sizes (1, 1.5, 2, and 4.5 kb) of IGF-I mRNA were recognized in the liver of juvenile carp. The two smaller species (1 kb and 1.5 kb) were not detected in adult carp. The expression of these two species was preferably induced by exogenous growth hormone administration in the liver of juvenile carp.
Coatomer, the cytosolic protein complex, consists of seven subunits (alpha-, beta-, beta'-, gamma-, delta-, epsilon-, and zeta-COP) and is involved in vesicle trafficking early in the secretory pathway in collaboration with a 20 kDa GTP-binding protein (ARF). In the present study, we have identified a yeast gene which encodes a protein having 39% amino acid sequence identity with bovine zeta-COP. This gene (YZC1 for Yeast Zeta COP) is essential for vegetative growth and the growth defect of delta yzc1 cells was restored by bovine zeta-COP cDNA. We isolated a temperature-sensitive mutant of YZC1 (yzc1ts) and examined its capacity for both the ER-to-Golgi transport and the double lysine motif (KKXX)-mediated retrograde transport from Golgi to ER. At non-permissive temperature, the yzc1ts cells exhibited a weak defect in the anterograde transport, but a strong defect in the retrograde vesicle transport. We conclude that Yzc1p is a yeast homologue of mammalian zeta-COP and participates mainly in the Golgi-to-ER retrograde transport.
Two distinct stress-activated protein kinase (JNKa and b) cDNAs were isolated from a carp ovary cDNA library. These cDNAs contained a full-length open reading frame encoding 427 amino acid residues with a predicted mass of 48.6 kDa. The deduced amino acid sequences of JNKa and b were 95.8% identical, with 18 residues replaced, and showed a high degree of sequence similarity to mammalian JNK/SAPK subgroup including the common dual phosphorylation motif of TPY. By Northern blot analysis, the carp JNKs were found to be abundant in the brain and ovary. Detailed study by RT-PCR assay revealed ubiquitous expression of JNKb, although expression of JNKa was specific to the brain and ovary. The high level expression of both JNKa and b in the ovary implies that JNKs play an important role in egg maturation or ectogenetic early development.
OBJECTIVE: To determine whether flushing of the facial skin in response to alcohol consumption (alcohol flushing) is a warning sign of hypertension. We also sought the relationship between alcohol flushing and other risk factors that may contribute to the development of hypertension. METHODS: We first investigated the relationship of the aldehyde dehydrogenase 2 (ALDH2) genotype to alcohol flushing for 53 normal volunteers. We evaluated the relationships among hypertension, alcohol consumption, and facial flushing for 1011 middle-aged Japanese men (aged 40-68 years; mean 51.6 +/- 5.5 years), on the basis of their responses to questionnaires and health records. RESULTS: The first examination of 53 normal volunteers showed that there were differences in the degree of alcohol flushing between the ALDH2 genotypes (P < 0.01). Hypertension was observed in 27.4% of the study population (277 of 1011), and was correlated positively to alcohol consumption (P < 0.01). The prevalence of hypertension differed significantly among these four groups: there was a 22.4% prevalence (70 of 312) among subjects with no flushing, a 33.8% prevalence (113 of 334) among those with slight flushing, a 27% prevalence (84 of 311) among those with visible flushing, and an 18.5% prevalence (10 of 54) among subjects who were almost completely intolerant to alcohol (P < 0.05). In particular, heavy drinkers who consumed > or = 1.5 Go (a traditional Japanese unit equivalent to 27 g ethanol) a day had a high prevalence of hypertension with slight and visible skin flushing [42% (63 of 150) and 40.7% (24 of 59), respectively]. That a family history of hypertension, greater age, heavy alcohol consumption, obesity, and symptoms of intoxication including flushing were correlated significantly to the prevalence of hypertension for all groups was demonstrated by multiple logistic regression analysis (P < 0.05). CONCLUSIONS: A repeated heavy alcohol intake could increase the risk of hypertension for Japanese subjects who exhibit skin flushing in response to alcohol consumption. Chronic alcohol intake by subjects with alcohol flushing might bring about a significant increase in blood acetaldehyde levels and cause an additional rise in the blood pressure.
Patients with advanced cervical cancers often have direct invasion of their carotid arteries. The prognosis for these patients with nonsurgical therapy is extremely poor. Because complete tumor removal is the only therapy that can offer these patients a chance for cure, carotid resection should be performed. We performed carotid resection and reconstruction on nine patients with advanced cervical cancers. Of these patients, none suffered from severe neurologic postoperative complications such as permanent hemiplegia. Three of the nine patients have been disease free for more than 24 months. These three patients would not have survived without carotid resection. Further study will show the usefulness of carotid resection and reconstruction in decreasing the morbidity and mortality in patients with cervical cancer involving the carotid artery.
To investigate whether there is an epidemiological correlation between Borna disease virus (BDV) infection and human neuropsychiatric diseases, we established a reverse-type sandwich enzyme-linked immunosorbent assay (RS-ELISA) for detecting specific antibodies to BDV. In this assay, microplate wells were coated dispersely with BDV p40 antigen, followed by the addition of test samples at a low dilution and then the biotinylated p40. A preformed complex of streptavidin and horseradish peroxidase-conjugated biotin and an enzyme substrate were used to measure the captured biotinylated p40. Theoretically, RS-ELISA should specifically detect anti-BDV antibodies without nonspecific signals; such signals possibly occur in conventional serological assays. Additionally, the RS-ELISA could be applied under the same protocols to test samples from a variety of animals. By using anti-BDV rat and rabbit sera, the assay was standardized so that it had high specificity and sensitivity. When we used the RS-ELISA to determine the presence of anti-BDV antibodies in plasma from 70 patients with chronic schizophrenia as well as 40 healthy individuals in the Tokyo area of Japan, no plasma sample was found to possess specific antibodies to BDV p40, indicating no association between BDV infection and the disease in our testing population. A negative reaction was also shown for the sera that had previously been judged to be seropositive for BDV by an immunofluorescence or immunoblot test. These findings suggested that false-positive cases of infection due to nonspecific reactions may be included in previous seroepidemiological information with regard to BDV.
We examined the responses of two Japanese monkeys with pollinosis to two major allergens (Cry j 1 and Cry j 2) of Japanese cedar pollen. The two monkeys (A and B) had specific IgE antibodies to the allergens and showed a strong positive reaction to both of them in the intradermal test. In the histamine release test with peripheral blood mononuclear cells (PBMC), monkey A showed a typical pattern similar to that seen in human patients, while monkey B released a low level of histamine. The proliferative response of PBMC to both allergens in monkey A was weak, but was typical in monkey B. From clinical as well as immunological points of view, these monkeys may be a suitable animal model for Japanese cedar pollinosis in humans.
The flavor of glutathione (gamma-L-glutamyl-L-cysteinylglycine, GSH) was examined by several sensory evaluations. The measurement of a point of subjective equality (PSE) showed that the peptide increases the flavor characteristics but did not affect the intensity of basic tastes, such as sweetness, saltiness, sourness, and umami. However, the threshold value of GSH decreased significantly in an umami solution containing 0.05% each of monosodium glutamate (MSG) and disodium inosinate (IMP). This suggests that GSH interacts with the umami substance and has a certain effect on the flavor. GSH had a characteristic kokumi flavor, such as continuity, mouthfulness, and thickness in the umami solution as well as in a model beef extract constructed from analyzed components at a concentration of 0.02% w/v. Some foodstuffs, including meat, were found to contain GSH above its threshold value, which implicates the contribution of GSH to the flavor. The thermal degradation study suggested that a part of GSH have changed into its disulfide, pyroglutamic acid (PCA), and cyclocysteinylglycine in cooked foodstuffs.
Embolism from a stenotic lesion of the extracranial internal carotid artery (ICS) is considered to be an important pathomechanism of cerebral infarction. The purpose of this study is to estimate the risk of cerebral infarction associated with microembolism in patients with ICS and thereby to determine the importance of TCD-detected microemboli in this condition. Seventy-one cases with more than 30% ICS and 10 cases without ICS were studied. TCD monitoring was carried out for an hour at the ipsilateral middle cerebral artery of each case using a 2-MHz pulse-wave transcranial Doppler device. High intensity transient signals were counted as microemboli. Microemboli were detected in 27 of 71 cases with ICS, but not in cases without ICS. Microemboli were detected more frequently in cases with 70% to 99% ICS (53.3%) compared with in cases with 30% to 69% ICS (12.5%). Cerebral infarctions were recognized in the ipsilateral hemisphere in 23 of 27 cases with microemboli (85.2%) by means of MRI. In contrast, cerebral infarctions were recognized only in 21 of 45 cases without microemboli (47.7%). These results suggest that a stenotic lesion of the extracranial internal carotid artery, especially high-grade stenosis, is a major source of cerebral embolism and that detection of microemboli by TCD is a useful tool capable of reliably assessing the risk of cerebral infarction due to ICS.
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A 56-year-old female with rheumatoid arthritis was admitted because of bilateral hip pain. In a few months of her hospitalization, a relatively abrupt renal dysfunction was emerged besides complement breakdown, and renal biopsy revealed crescentic glomerulonephritis. Immunofluorescence study showed peripheral granular deposits of IgG, IgM, and C3 in the glomeruli. Cresents were predominantly composed of macrophages and glomerular epithelial cells. Amyloid nephropathy, renal vasuculitis, and association of other collagen vascular diseases were negligible for the causative factor. It was suggested that immune complexes were formed in the glomeruli, in which both humoral and cellular immune responses were to be induced, that brought cescents formation in the lesions. Crescentic glomerulonephritis in patients with rheumatoid arthritis is rare and a possible pathogenetic mechanisms involved in the development of renal dysfunction are discussed with the special reference to immune complex-induced inflammation.
To clarify the relationship between vestibular and visual (optokinetic) stimuli in normal children, we investigated the vestibulo-ocular reflex (VOR) and visual VOR (VVOR). The subjects were 20 healthy children aged 3-6 years and 24 healthy adults aged 21-29 years. The VOR gains and phase were measured under two visual conditions: with eyes open in complete darkness and with eyes open in a lighted optokinetic drum. In both visual conditions, phase did not significantly differ between children and adults. In the dark, children presented a significantly larger gain than that of adults. In the optokinetic drum, however, the gain values of the children were almost the same as in adults. We suggest that the large VOR gain values of children may be due to immaturity of the inhibitory regulation system of the VOR.
The subjective vertical was estimated by using a concentrically movable spotlight-line on a specially devised dome-shaped screen and a controller in patients with unilateral vestibular disorders. The test was performed in a dark room to measure the deviation of the subjective vertical from the true vertical to the earth gravity. The result showed characteristic deviation of the subjective vertical to the affected ear side in most subjects. The relationship between the subjective deviation and body sway was investigated to estimate the clinical significance of the subjective vertical. The locus pattern, area, locus length and the trajectory of head movements while measuring the subjective vertical were recorded. The patterns were centripetal or right-left types, the values of the head movement seemed to be proportional to the magnitude of the subjective vertical. The time course of the subjective vertical depended on the stage of the disorder. Some cases with active vestibular disorders showed directional changes of the subjective vertical deviation depending on the extent of the lesion. The most interesting results were obtained in the relationship between the caloric response and the subjective vertical, suggesting the clinical significance of the subjective vertical in vestibular function.
Examination was made of the pharmacological characteristics of Sho-seiryu-to, an antiallergic kampo medicine. Sho-seiryu-to suppressed histamine release from rat peritoneal mast cells, but failed to inhibit the binding of [3H]-mepyramine to histamine H1 receptors in guinea pig cerebral cortex and lung. Sho-seiryu-to had no effect on cutaneous reactions induced by serotonin, platelet-activating factor (PAF), leukotriene (LT) C4 or LTD4. Ketotifen prolonged electrically induced convulsions, while Sho-seiryu-to did not. Sho-seiryu-to did not affect salivation induced by pilocarpine. Sho-seiryu-to thus does not appear to inhibit histamine H1 receptors or inflammation induced by serotonin, PAF, LTC4 and LTD4, but suppresses mast cell activity. Sho-seiryu-to would thus have only a few side effects such as dry mouth and convulsions due mainly to the blockage of the action of muscarinic in salivary glands and histamine in the brain.