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Biomedical subjects

M Sakaguchi

Publications and source records attributed to M Sakaguchi.

At least 181 records · Page 10Linked to original sources
PubMed1998

Membrane topology of NADPH-cytochrome P450 reductase on the endoplasmic reticulum.

Topology of the membrane-anchoring segment of mouse NADPH-cytochrome P450 reductase in the endoplasmic reticulum membrane was elucidated. An N-glycosylation site was generated in the amino-terminal hydrophilic sequence of the reductase, and the mutated protein was expressed in a cell-free system in the presence of microsomal vesicles. The in vitro synthesized reductase protein was integrated into the microsomal membrane and N-glycosylated depending on the presence of signal recognition particles. We conclude that the amino-terminal membrane-anchoring segment of the reductase is a type I signal-anchor sequence which shows amino-terminus-lumen and carboxy-terminus-cytoplasm topology.

Amino Acid Sequence↗
PubMed1998

Two-dimensional gel electrophoretic analysis of the changes after immortalization of human cells: decrease of intracellular alpha-2-macroglobulin fragment.

To study the mechanisms of immortalization of human cells, an early step in cancer development, we compared the cellular proteins of normal and immortalized human fibroblasts. Two-dimensional gel electrophoresis showed that one spot with a molecular mass 20 kDa and an isoelectric point of 6.0, became significantly smaller after immortalization of human cells. Further, the spot was rarely observed in four human liver cancer cell lines. Investigation of the N-terminal amino acids revealed that the spot was a fragment of alpha-2-macroglobulin. Although the 20 kDa fragment contains methionine, the spot was not labeled with [35S]methionine. Thus we concluded that the spot might be derived from the culture medium. These results indicated that intracellular metabolism of a-2-macroglobulin, which is a multifunctional protease inhibitor, changed after the cells were transformed.

Cell Line↗
PubMed1998

Small spot sign of rectal carcinoma by endorectal ultrasonography: histologic relation and clinical impact on postoperative recurrence.

PURPOSE: We observed small spots at the margin of rectal carcinomas on endorectal ultrasonography. Our aim was to study the relationship between ultrasonographic evidence of these spots and histologic characteristics of disease and postoperative recurrence. PATIENTS AND METHODS: The study group comprised 55 patients, 36 men and 19 women, with rectal carcinoma as confirmed by biopsy. The patients were followed up at three-month intervals for six months to three years and six months after the operation. Endorectal ultrasonography was performed in the usual manner. Surgically resected specimens were stained with hematoxylin and eosin and histologically examined. Vessel invasion was graded from 0 (not invasive) to 3 (most invasive). RESULTS: Among the 55 patients studied, 3 had Stage T2,N0,M0 rectal carcinomas and 35 had Stage T3,N0,M0 carcinomas, 5 (14.3 percent) of whom had echographic evidence of small spots. Thirteen patients had Stage T3,N1/2,M0 carcinomas, comprising 12 (92.3 percent) with small spots, and four patients had T3,N1/2,M1 carcinomas, all with small spots. Vessel invasion of Grade 2 or higher was observed around the carcinomas in 20 of 21 patients who had small spots. Ten of 13 patients with many spots at the margin of the carcinoma (a spot grade of ++) histologically had marked venous or lymphatic invasion (an invasion Grade 3). The presence of small spots was closely associated with massive venous or lymphatic invasion (a vessel invasion grade of 2 or more). Four patients had synchronous liver metastases, and small spots were found in all four. Distant metastases and local recurrence were found in 11 of 21 patients with small spots. We found no recurrence in any patient without small spots on endorectal ultrasonography. CONCLUSIONS: Small spots indicate the presence of massive venous or lymphatic invasion and a high risk of postoperative recurrence.

Aged↗
PubMed1998

Limitation of endorectal ultrasonography: what does a low lesion more than 5 mm in size correspond to histologically?

PURPOSE: The accuracy of diagnosis of metastatic lymph nodes for rectal carcinoma has not improved. A low echoic lesion more than 5 mm in size detected by endorectal ultrasonography is preoperatively assessed as a metastatic lymph node. What does a low echoic lesion more than 5 mm in size correspond to histologically? METHODS: Forty-seven patients with lower rectal carcinoma (Term I, 1986-1990) and 48 patients with lower rectal carcinoma (Term II, 1991-1995) undergoing endorectal ultrasonography were reviewed. Surgically resected rectal specimens from 40 patients with rectal carcinoma underwent ultrasonography. Low echoic lesions more than 5 mm in size were taken from resected specimens and were stained with hematoxylin, followed by histologic examination. RESULTS: The accuracy of diagnosis of metastatic lymph nodes of Term II was not higher than that of Term I. Twenty-five low echoic lesions were detected by ultrasonography using 40 resected specimens. Seventeen of these 25 lesions (68 percent) were histologically confirmed to be metastatic lymph nodes. One of 25 (4 percent) was found to be lymphadenitis with no metastasis. Among the 25 lesions, 5 (20 percent) were histologically confirmed to be tumor deposits, 2 (8 percent) fatty tissue, and 22 (88 percent) carcinoma. CONCLUSIONS: Low echoic lesions were histologically confirmed to be tumor deposits (20 percent) and metastatic lymph nodes (68 percent). Although these data show deficiencies and limitations of the accuracy of endorectal ultrasonography, they compare favorably with other series, and no other current technology can show similar accuracy.

Endosonography↗
PubMed1998

Oral administration of a dominant T-cell determinant peptide inhibits allergen-specific TH1 and TH2 cell responses in Cry j 2-primed mice.

BACKGROUND: Oral immunotherapy with a peptide for allergic immune responses is theoretically a promising therapy but has not been established yet. OBJECTIVE: To evaluate immune suppressive efficacy of oral administration of an immunodominant peptide, we investigated changes in T-cell proliferation, TH1 - and TH2 -cytokine production, and TH1 - and TH2 -mediated antibody production in mice after oral administration of a peptide. METHODS: Peptide p246-259, containing a dominant T-cell determinant of Cry j 2, which is the major allergen in Japanese cedar pollen, was used in this study. Groups of mice received p246-259 or PBS alone before or after they were primed intranasally with Cry j 2 and cholera toxin. In another experiment mice were primed intraperitoneally with Cry j 2 and alum. Proliferative response and cytokine production by nasal-associated lymph node cells against Cry j 2 were investigated. Amounts of systemic anti-Cry j 2 IgE and IgG antibodies were also measured. RESULTS: Oral administration of the peptide to mice before, or even after, the sensitization induced oral tolerance in T-cell responses against the allergen; the tolerance was associated with decreased production of TH1 (IFN-gamma and IL-2) and TH2 (IL-4) cytokines. Allergen-specific TH1 -mediated (IgG2a and IgG2b) and TH2 -mediated (IgG1 and IgE) antibody responses were also inhibited. CONCLUSIONS: Oral administration of a dominant T-cell determinant peptide induces immunologic tolerance in both TH1 and TH2 cell responses against the whole protein allergen. Our study is the first, to our knowledge, to demonstrate the potential for peptide-based oral immunotherapy in order to treat allergic immune responses.

Administration, Intranasal↗
PubMed1998

Acetylcholine reactivates latent pseudorabies virus in mice.

The latency model of pseudorabies virus (PrV) wild strain, YS-81, in mice was established and latent PrV reactivated with acetylcholine. The latent PrV was reactivated from the trigeminal ganglia with acetylcholine. It was found that this model is useful in investigating the mechanism of latent PrV reactivation by acetylcholine.

Acetylcholine↗
PubMed1998

Two patterns of systemic immediate-type reactions to Japanese encephalitis vaccines.

We have found two different patterns of systemic immediate-type reactions to Japanese encephalitis vaccine containing gelatin as the stabilizer. One group of affected children had cutaneous and respiratory symptoms (e.g., systemic urticaria and wheezing) and the other group had cardiovascular symptoms (e.g., hypotension and cyanosis) without cutaneous and respiratory symptoms. The children in the former group had anti-gelatin IgE in their sera, whereas those in the latter group did not. We think that the two patterns may be caused by different mechanisms or different allergens.

Cardiovascular Diseases↗
PubMed1998

Protection of chickens with or without maternal antibodies against both Marek's and Newcastle diseases by one-time vaccination with recombinant vaccine of Marek's disease virus type 1.

We constructed a stable recombinant Marek's disease virus type 1 (rMDV1) expressing the fusion protein (F) of Newcastle disease virus (NDV) by inserting the coding sequence within the US10 gene of MDV1 by homologous recombination and designated this as rMDV1-US10L(F). The NDV-F protein was significantly expressed under control of the SV40 late promoter in cultured cells infected with the rMDV1. To examine the protective efficacy of the rMDV1, specific pathogen-free (SPF) chickens were vaccinated with rMDV1 at one-day-old. Almost all birds (> 95%) were protected from NDV challenge via intramuscular, ocular, intranasal and intratrachial routes at 4 weeks after vaccination. The rMDV1 showed 100% protection against virulent MDV1 challenge in SPF chickens. Antibody responses against NDV-F and MDV1 antigens were observed at least up to 11 weeks after immunization. When the sera from chickens vaccinated with the rMDV1 were examined for the presence of anti-NDV-F antibody on the day of NDV challenge, the vaccinated bird group which did not survive from NDV challenge were found to show lower antibody titers than the surviving group. The rMDV1 also provided sufficient protection against NDV and MDV1 challenges in commercial chickens with maternal antibodies against NDV-F and MDV1 antigens.

Animals↗
PubMed1998

Cases of systemic immediate-type urticaria associated with acellular diphtheria-tetanus-pertussis vaccination.

The authors found eight children who had systemic urticaria within 30 min after administration of acellular diphtheria-tetanus-pertussis (DTP) vaccines which contain gelatin as a stabilizer. The authors measured the specific IgE to gelatin and DTP toxoids in their sera, and found that none of the children had anti-gelatin IgE. Of the eight children, two had detectable levels of anti-toxoid IgE. As a negative control, of the 10 children who showed no allergic reaction to the acellular DTP vaccines, four also had detectable levels of anti-toxoid IgE. From these results, there was no obvious relationship between the specific IgE to the vaccine's component proteins and systemic urticaria to acellular DTP vaccines.

Bacterial Proteins↗
PubMed1998

Forced transmembrane orientation of hydrophilic polypeptide segments in multispanning membrane proteins.

In a current model of integration of multispanning membrane proteins into the endoplasmic reticulum, it is proposed that the transmembrane segments show alternating translocation initiation and stop-transfer functions. Here, we present evidence for a mode of cotranslational insertion in which an internal signal-anchor sequence with Nexo/Ccyt topology confers a transmembrane disposition onto a preceding hydrophilic segment, resulting in a topology where the hydrophilic segment apparently can slip back and forth across the membrane. Our results demonstrate that hydrophobicity is not, as hitherto thought, an absolute requirement for the formation of a transmembrane segment, and suggest that integral membrane proteins may contain hydrophilic transmembrane segments with a considerable freedom to move in relation to the membrane.

Animals↗
PubMed1998

Human perspiration measurement.

We review various methods developed for human perspiration measurement and their physiological applications, with special reference to the performance and application of a new home-made ratemeter and instrumentation with a microscope. Many kinds of humidity sensor based on humidity-sensitive electrical properties have been investigated and placed on the market. Recently a capacitive thin-film humidity sensor was constructed and confirmed to be one of the best humidity sensors for accurately and quickly detecting changes in the relative humidity of gas-flow perfused through a ventilated chamber for human perspiration measurement. In this paper we also introduce a new home-made ratemeter with a capacitive humidity sensor, the electrical output of which is not disturbed by changes in ambient temperature, and new instrumentation for directly observing drops of sweat secreted from eccrine glands in human skin and simultaneously measuring the change in amount of perspiration at the same area of skin. Finally, we review physiological applications of the methods for measuring human palmar perspiration including emotional sweating.

Humans↗
PubMed1998

Identification of potential regulatory elements for the transport of Emp24p.

To examine the possibility of active recycling of Emp24p between the endoplasmic reticulum (ER) and the Golgi, we sought to identify transport signal(s) in the carboxyl-terminal region of Emp24p. Reporter molecules were constructed by replacing parts of a control invertase-Wbp1p chimera with those of Emp24p, and their transport rates were assessed. The transport of the reporter was found to be accelerated by the presence of the cytoplasmic domain of Emp24p. Mutational analyses revealed that the two carboxyl-terminal residues, leucine and valine (LV), were necessary and sufficient to accelerate the transport. The acceleration was sequence specific, and the terminal valine appeared to be more important. The LV residues accelerated not only the overall transport to the vacuole but also the ER to cis-Golgi transport, suggesting its function in the ER export. Hence the LV residues are a novel anterograde transport signal. The double-phenylalanine residues did not affect the transport by itself but attenuated the effect of the anterograde transport signal. On the other hand, the transmembrane domain significantly slowed down the ER to cis-Golgi transport and effectively counteracted the anterograde transport signal at this step. It may also take part in the retrieval of the protein, because the overall transport to the vacuole was more evidently slowed down. Consistently, the mutation of a conserved glutamine residue in the transmembrane domain further slowed down the transport in a step after arriving at the cis-Golgi. Taken together, the existence of the anterograde transport signal and the elements that regulate its function support the active recycling of Emp24p.

Amino Acid Sequence↗
PubMed1998

Existence of two isoforms of extracellular signal-regulated kinase in fish.

Full-length cDNAs for extracellular signal-regulated kinases (ERK1 and ERK2) were isolated from a carp ovary cDNA library. The deduced amino acid sequences of carp ERK1 (cERK1) and ERK2 (cERK2) exhibited high degrees of homology to the known sequences of the ERK group. Northern blot analysis showed that cERK1 mRNA was not expressed in a tissue-specific manner, though the level of expression of cERK2 mRNA varied among tissues. Western blot analysis of the brain, kidney, and ovary confirmed the expression of cERK1 and cERK2 in carp. Our findings indicate that two isoforms of ERK, ERK1 and ERK2, exist in fish.

Amino Acid Sequence↗
PubMed1998

Characterization of the initial steps of precursor import into rat liver mitoplasts.

Mitochondria have two independent protein-import machineries, one in the outer membrane (the Tom system) and the other in the inner membrane (the Tim system). Here, we have characterized the initial steps of precursor import into rat liver mitoplasts. The import reaction was separated into two stages, consisting of precursor binding to the mitoplasts at 0-10 degreesC, and a subsequent chase reaction at 30 degreesC. This assay revealed four distinct precursor-import steps: DeltaPsi-dependent initial binding of the precursor, precursor transfer to the Tim23-Tim17 stage, DeltaPsi-dependent translocation of the presequence across the inner membrane, and the complete translocation of the mature portion of the precursor. Antibodies against the intermembrane space domain of Tim23 inhibited neither the precursor binding nor the subsequent translocation of the presequence across the inner membrane. In contrast, the antibodies inhibited the complete translocation of the mature domain of the precursor across the inner membrane. Immunoprecipitation with anti-Tim23 IgGs revealed that the precursor-Tim23 complex increased with time and temperature after the initial targeting of the precursor to the mitoplasts. These results suggest that the precursor is first targeted to the inner membrane component DeltaPsi-dependently, then transferred to the Tim system consisting of Tim23-Tim17, and finally imported into the matrix.

Amino Acid Sequence↗
PubMed1998

Endoscopic retrograde cholangiopancreatography in paediatric patients with biliary disorders.

Endoscopic retrograde cholangiopancreatography (ERCP) has long been used in children. The usefulness of ERCP in paediatric patients with various biliary disorders, however, has not been well documented. Thirty-two sessions of ERCP performed in 29 paediatric patients ranging in age from 1 month to 15 years were evaluated. Endoscopic retrograde cholangiopancreatography was to confirm diagnosis or to obtain detailed information about their pancreaticobiliary system. Cannulation was successful in all patients. Opacification of the biliary tracts was also successful in all except for three patients with extrahepatic biliary atresia. Endoscopic retrograde cholangiopancreatography was assessed to be successful in making a differential diagnosis of neonatal hepatitis from extrahepatic biliary atresia, and in having a confirmed diagnosis of anomalous arrangement of the pancreaticobiliary ductal system associated with choledochal cyst. The procedure was also useful for obtaining detailed information on the pancreaticobiliary system in the other children. No accidents occurred during the endoscopic procedures in any of the paediatric patients. When a confirmed diagnosis or detailed information is needed in paediatric patients with biliary disorders, ERCP is a useful and safe technique.

Adolescent↗
PubMed1998

A new concept in polytopic membrane proteins following from the study of band 3 protein.

In the present communication, we introduce a novel concept in multispanning polytopic membrane proteins revealed by the study of the band 3 protein. The transmembrane domain of such proteins can be divided into three categories, that is, hydrophilic loops connecting transmembrane peptides (category 1), portions embedded by peptide-peptide interactions (category 2), and portions embedded by peptide-lipid interactions (category 3). Category 2 peptides of polytopic membrane proteins were found to stably reside in the lipid bilayer without peptide-lipid interactions that had been thought to be essential for transmembrane segments. Category 3 peptides are equivalent to single-spanning segments of bitopic membrane proteins. Three different experiments, namely proteolytic digestion, chemical modification of the band 3 protein, and cell free transcription and translation, were used to categorize the transmembrane peptides.

Animals↗