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Biomedical subjects

J Sakai

Publications and source records attributed to J Sakai.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Cytomegalovirus retinitis and Pneumocystis carinii choroidopathy in a patient with AIDS].

A case of Pneumocystis carinii (P. carinii) choroidopathy is reported. The patient was a 17-year-old man with acquired immunodeficiency syndrome (AIDS) who developed bilateral, multifocal, yellow-white, round, flat choroidal lesions ranging in size from 1/8 to 1/6 of the disc diameter while undergoing treatment for cytomegalovirus retinitis. He had had P. carinii pneumonia 43 months previously, and received inhaled pentamidine as suppressive therapy. Over a 4-week period of observation, the choroidal lesions appeared to enlarge slowly and increased in number in the posterior pole, with no clinical evidence of intraocular inflammation and retinal involvement. He was diagnosed as having P. carinii choroidopathy and treated with intravenous pentamidine. Three months after systemic pentamidine therapy was begun the choroidal lesions disappeared. Despite the fact that P. carinii choroidopathy is a rare opportunistic ocular infection, ophthalmic manifestations may be an important initial marker of extrapulmonary disseminated infection in some patients. Therefore we recommend ophthalmologic examinations in patients with AIDS who receive long-term aerosolized pentamidine prophylaxis for pneumonia.

AIDS-Related Opportunistic Infections↗
PubMed1996

[The Hanshin-Awaji earthquake and the recurrence of endogenous uveitis].

The recurrence mechanism of endogenous uveitis remains to be explained, but it is popularly believed that hereditary background and environmental changes affect this mechanism. On Jan 17, 1995, the Hanshin-Awaji distinct in Japan was struck by a major earthquake. Over 6,300 people were killed and more than 310,000 were made homeless. The inhabitants of this area suffered emotional stress from the sudden changes in their living environment. In 116 endogenous uveitis patients who were being followed up for more than 2 years after Jul 17, 1993, at Kobe University Hospital in the stricken area, we investigated the recurrence rate of endogenous uveitis before and after the earthquake. The recurrence rate after the earthquake was significantly higher than before the earthquake (10% vs 3%), and women were more often affected than men after the earthquake. Our data suggests that psychological stress from sudden changes in the living environment after the earthquake can trigger the recurrence of endogenous uveitis. It might be important to provide psychological as well as physical care of endogenous uveitis patients after a disaster.

Adolescent↗
PubMed1995

Hairpin orientation of sterol regulatory element-binding protein-2 in cell membranes as determined by protease protection.

Sterol regulatory element-binding proteins (SREBP-1 and SREBP-2) are proteins of approximately 1150 amino acids each that are attached to membranes of the endoplasmic reticulum (ER). In sterol-depleted cells, a protease releases an NH2-terminal fragment of approximately 500 amino acids that contains a basic helix-loop-helix leucine zipper motif. This fragment enters the nucleus and stimulates transcription of genes encoding the low density lipoprotein receptor and enzymes of cholesterol biosynthesis. Prior evidence indicates that the SREBPs are attached to membranes by virtue of an 80-residue segment located approximately 80 amino acids to the COOH-terminal side of the leucine zipper. This segment contains two long hydrophobic sequences separated by a short hydrophilic sequence of approximately 30 amino acids. We have proposed a hairpin model in which the two hydrophobic sequences span the membrane, separated by the short hydrophilic sequence which projects into the lumen of the ER (the "lumenal loop"). The model predicts that the NH2- and COOH-terminal segments face the cytosol. To test this model, we constructed a cDNA encoding human SREBP-2 with epitope tags at the NH2 terminus and in the lumenal loop. The COOH-terminal region was visualized with a newly developed monoclonal antibody against this region. Sealed membrane vesicles were isolated from cells expressing the epitope-tagged version of SREBP-2. Trypsin treatment of these vesicles destroyed the NH2- and COOH-terminal segments and reduced the lumenal epitope to a size consistent with protection of the lumenal sequence plus the two membrane-spanning segments. The lumenal epitope tag contained two potential sites for N-linked glycosylation. The size of the trypsin-protected fragment was reduced by treatment with N-Glycanase and endoglycosidase H, indicating that this segment was located in the lumen of the ER where it was glycosylated. These data provide strong support for the hairpin model.

Amino Acid Sequence↗
PubMed1995

Identification and characterization of a pre-cleavage synaptic complex that is an early intermediate in Tn10 transposition.

The Tn10 transposition reaction has been reconstituted in vitro on short linear substrate fragments encoding transposon ends. This permits the direct detection of protein-DNA complexes formed during transposition by gel retardation analysis. We demonstrate that a stable synaptic complex containing transposase and a pair of transposon ends forms rapidly and efficiently, prior and prerequisite to the double-strand cleavages involved in transposon excision. These observations extend the general analogies between the Tn10 and Mu transposition reactions, and also reveal significant differences between the two cases. The speed and simplicity of synaptic complex formation in the Tn10/IS10 reaction is suitable for a modular insertion sequence. In contrast, the relative slowness and complexity of this process in the Mu is necessary to permit transposition immunity and control of transposition by Mu repressor protein, two features specifically important for a temperate bacteriophage. Further dissection of the reaction leads to a tentative working model for events preceding the first double-strand cleavage.

Bacteriophage mu↗
PubMed1995

Nucleotide sequence analysis of two nuclear inclusion body and coat protein genes of a sweet potato feathery mottle virus severe strain (SPFMV-S) genomic RNA.

Recombinant DNA molecules containing cDNA of a sweet potato feathery mottle virus severe strain (SPFMV-S) RNA genome were constructed and the partial nucleotide sequences were determined for three DNA inserts, which cover 4-2 kb from the 3'-terminus excluding the poly (A) tail. This region of the genome consists of an open reading frame of 1340 amino acids (a.a.) and a 3'-non-translated region of 224 nucleotides. The protein products expected were 6K2 (53 a.a.), NIa (435 a.a.), NIb (521 a.a.) and CP (315 a.a.). Among NIa, NIb and coat proteins, the NIb protein was found to be the most conserved (59-68%) when compared to the corresponding proteins of other distinct potyviruses.

Amino Acid Sequence↗
PubMed1995

Sequence and domain organization of scruin, an actin-cross-linking protein in the acrosomal process of Limulus sperm.

The acrosomal process of Limulus sperm is an 80-microns long finger of membrane supported by a crystalline bundle of actin filaments. The filaments in this bundle are crosslinked by a 102-kD protein, scruin present in a 1:1 molar ratio with actin. Recent image reconstruction of scruin decorated actin filaments at 13-A resolution shows that scruin is organized into two equally sized domains bound to separate actin subunits in the same filament. We have cloned and sequenced the gene for scruin from a Limulus testes cDNA library. The deduced amino acid sequence of scruin reflects the domain organization of scruin: it consists of a tandem pair of homologous domains joined by a linker region. The domain organization of scruin is confirmed by limited proteolysis of the purified acrosomal process. Three different proteases cleave the native protein in a 5-kD Protease-sensitive region in the middle of the molecule to generate an NH2-terminal 47-kD and a COOH-terminal 56-kD protease-resistant domains. Although the protein sequence of scruin has no homology to any known actin-binding protein, it has similarities to several proteins, including four open reading frames of unknown function in poxviruses, as well as kelch, a Drosophila protein localized to actin-rich ring canals. All proteins that show homologies to scruin are characterized by the presence of an approximately 50-amino acid residue motif that is repeated between two and seven times. Crystallographic studies reveal this motif represents a four beta-stranded fold that is characteristic of the "superbarrel" structural fold found in the sialidase family of proteins. These results suggest that the two domains of scruin seen in EM reconstructions are superbarrel folds, and they present the possibility that other members of this family may also bind actin.

Acrosome↗
PubMed1995

[The control of smooth muscle tissues by nonadrenergic noncholinergic (NANC) nerve fibres in the autonomic nervous system].

Smooth muscle cells distributed in the visceral organs are under the control of the autonomic nervous system, and contraction or relaxation of the muscle cells plays an important physiological role in the control of blood pressure, motility of the digestive, respiratory and urinary tracts and secretion. Recent physiological, pharmacological and histochemical investigations indicate that neurotransmitters other than acetylcholine or noradrenaline are involved in peripheral autonomic neuro-effector transmission, and these neurotransmitters are generally termed non-adrenergic, non-cholinergic (NANC) neurotransmitters. The neurotransmitters responsible for excitatory and inhibitory NANC neurotransmission (e-NANC and i-NANC respectively) have not been conclusively identified, but ATP, nitric oxide (NO) and peptides such as VIP and substance P are candidates for these roles. In this review, we discuss the possible role of ATP and NO as e- or i-NANC neurotransmitter in the digestive, respiratory and urinary tracts. Much of the work on NANC innervation in the digestive tract has been carried out on the circular muscle layers of the ileum. This receives inhibitory NANC innervation with ATP responsible for fast relaxation and VIP, and possibly NO, for the slow response. Early and late excitatory junction potentials can be recorded in the presence of atropine. The second is due to substance P since it is blocked in the presence of spantide and by desensitization of the tissue with high doses of substance P. The transmitter responsible for the early NANC contraction has not been identified. Electrical field stimulation (EFS) applied to the tracheal smooth muscle during contraction induced by 5-HT in the presence of atropine and guanethidine elicited monophasic NANC relaxation. By contrast, NANC relaxation elicited in the smaller airways was biphasic, comprising an initial fast component followed by a second slow one. L-NAME selectively abolished the first component without affecting the second. VIP-antagonists or alpha-chymotrypsin considerably attenuated the amplitude of the L-NAME insensitive relaxation. These results indicate that at least two neurotransmitters, possibly NO or NO-containing compounds and VIP, are involved in i-NANC neurotransmission in the airway. In the urinary bladder a large, transient atropine resistant contraction occurs in response to pelvic nerve stimulation. This is blocked by alpha, beta methylene ATP suggesting that it is due to ATP. There is no evidence of inhibitory innervation. In the urethra contraction is completely blocked by atropine and guanethidine; a rapid NANC relaxation is abolished by drugs that block NO synthesis. Nerves containing peptides supply both urethra and bladder and may also be involved. These results suggest that all visceral smooth muscles may receive inhibitory NANC innervation involving NO. ATP produces contraction of the urinary bladder but relaxation of the digestive tract. The role of peptides is not yet clear but there is evidence that substance P may be an excitatory transmitter and VIP an inhibitory transmitter in many organs.

Adenosine Triphosphate↗
PubMed1995

Distribution of thyrotropin releasing hormone receptor in rats: an immunohistochemical study.

Thyrotropin releasing hormone (TRH) receptor was identified immunohistochemically in the rat tissues using anti-peptide antiserum. Anti-TRH receptor antiserum was raised in New Zealand white rabbits immunized with a conjugate of synthetic TRH-receptor peptide (15-28) to bovine serum albumin. Immunohistochemical analysis was performed by the avidin-biotin complex method. TRH-receptor immunoreactivity was visualized in the central nervous system and anterior pituitary thus supporting previous investigations of TRH receptor distribution using in vitro autoradiographic ligand binding. Significant stain was detected in neural perikarya, axons and dendrites as well as in many cells of the retina, adrenal medulla, stomach mucosa, Auerbach's nervous branch and Mysner's nervous branch of the stomach, small intestine and colon. When using antiserum preincubated with synthetic TRH-receptor peptide (15-28) or rat anterior pituitary homogenate which contains TRH-receptor peptide, no significant stain of the anterior pituitary cells or neurons in the hypothalamus was detected. These findings suggest that TRH-receptor is widely distributed and that this method is valuable in studying the distribution of TRH-receptor in rats.

Journal Article↗
PubMed1995

Distribution of somatostatin receptor type 1 in the rat. An immunohistochemical study.

Somatostatin receptor type 1 (SSTR-1) was identified immunohistochemically in the rat tissues using anti-peptide antiserum. Anti-somatostatin receptor antiserum was raised in New Zealand white rabbits immunized with a conjugate of synthetic SSTR-1 peptide (41-52) with bovine serum albumin. Immunohistochemical analysis was performed by the ABC method. SSTR-1 immunoreactivity was visualized in the central nervous system, anterior pituitary, mucosa of stomach and duodenum, Auerbach's nervous branch and Mysner's nervous branch of gastrointestinal tract and pancreas. Significant staining was detected in neural perikarya, axon and dendrite. When using antiserum preincubated with synthetic SSTR-1 peptide (41-52) or rat anterior pituitary homogenated which contains SSTR-1, no significantly stained anterior pituitary cells or neurons in the hypothalamus were detected. These findings suggest that SSTR-1 is widely distributed and that this method is valuable in studying the distribution of somatostatin receptor in rats.

Journal Article↗
PubMed1995

[Incidence of uveitis at Tokyo Medical College Hospital].

We reviewed the records of 980 patients with endogenous uveitis who were followed in the uveitis clinic of the Tokyo Medical College Hospital, Department of Ophthalmology. A group of 693 patients examined within a 5-year period from January, 1989 through December, 1993 (Group A) were compared to an earlier group of 287 patients examined within a 3-year period from January, 1982 through December, 1984 (Group B). The incidence of Behçet's disease, intermediate uveitis, and toxoplasmosis showed an apparent decrease. In contrast, the incidence of sarcoidosis and acute anterior uveitis increased. In comparison to Group B, Group A showed an increased number of patients with virus-associated uveitis, toxocariasis, and uveitis caused by fungal infection. The changes observed in the prevalence of certain uveitic diseases in the patient population we followed may be related to changing environment and/or life style, in addition to various advances in diagnostic testing. In the future, the classification of uveitis will become more varied according to the establishment of new concepts.

Adolescent↗
PubMed1994

Structure, chromosome location, and expression of the human very low density lipoprotein receptor gene.

Isolation and characterization of cDNAs encoding human very low density lipoprotein (VLDL) receptor revealed the presence of two forms of the receptor: one consists of five domains that resemble the low density lipoprotein (LDL) receptor, and a variant form lacks an O-linked sugar domain. More than 96% of amino acids in the human and rabbit VLDL receptors are identical, whereas those in the LDL receptors are less conserved between the two species (76%). The human VLDL receptor gene contains 19 exons spanning approximately 40 kilobases. The exon-intron organization of the gene is almost the same as that of the LDL receptor gene, except for an extra exon that encodes an additional repeat in the ligand binding domain of the VLDL receptor. Analysis of DNA from human-rodent hybrid cells revealed that the gene is located on chromosome 9. Although the 5'-flanking region of the VLDL receptor gene contains two copies of a sterol regulatory element-1 like sequence, the levels of mRNA for the receptor in THP-1 human monocytic leukemia cells were unchanged by sterols. The 5'-untranslated region of the receptor mRNA contains a polymorphic triplet repeat found also in the fragile X syndrome gene.

Amino Acid Sequence↗
PubMed1994

[VLDL receptor].

The LDL receptor was discovered by Goldstein and Brown in 1974. This discovery has led to dramatic progress toward understanding the mechanisms of cholesterol homeostasis. Recently we have found a second lipoprotein receptor that specifically binds apoE-containing lipoproteins. This new lipoprotein receptor designated VLDL receptor is composed of five functional domains that resemble the LDL receptor. The VLDL mRNA is abundant in heart, muscle and adipose tissue, suggesting that the receptor mediates the uptake of triglyceriderich lipoproteins thereby providing muscle and fat cells with fatty acid.

Amino Acid Sequence↗
PubMed1994

[Two cases of Paragonimus westermani in one family].

A 68-year-old woman and her 28-year-old son ate some rare fresh-water crabs (Eriocheir japonicus). The son became ill one month later with pleural effusion. After 10 months the mother's symptoms included cough, hemosputum and a nodular shadow on her chest X-ray. Eosinophilia was present and the Ouchterlony test showed strong bands toward Paragonimus westermani antigen in both patients. They were diagnosed as having Paragonimiasis westermani. The symptoms stopped after Bithionol administration and the bands of the Ouchterlony test also disappeared. The difference in the latent stage and clinical symptoms of these patients, who were infected at the same time, is interesting as it highlights the importance of observing other people who may have been infected with Paragonimus westermani.

Adult↗
PubMed1994

[The effect of ocular and/or pineal body removal in mice with spontaneously developing uveoretinitis].

Autoimmune uveoretinitis and pinealitis have been shown to develop spontaneously in BALB/c nude mice after their T cell function has been reconstituted by embryonic F344 rat thymus grafting (TG nude mice). Because anti-IRBP antibodies were detected in these mice, it was concluded that IRBP was the target antigen. In this study, we removed the eyes and/or the pineal body from TG nude mice, and examined anti-IRBP antibodies in their sera. It appeared that IRBP originating from the eyes and the pineal body were the immunogenic antigens in the TG nude mice, but the IRBP from the eyes was found to be more immunogenic and pathogenic than that from the pineal body. We also found that the incidence of uveoretinitis increases with pinealectomy in TG nude mice, even though the immune system is not affected.

Animals↗
PubMed1993

In vivo stimulation of thyroid hormone release by rabbit antibodies with thyroid stimulating activity raised against the mutated receptor peptide TSH-R-HIS17.

The present study was designed to examine whether thyroid stimulating antibodies (TSAb) against the mutated or non-mutated peptide of human TSH receptor stimulates release of thyroid hormones in mice in vivo. We generated antibodies against mutated TSH receptor peptide TSH-R-HIS17 and non-mutated TSH receptor peptide TSH-R-ASP17 immunizing the peptides to rabbits. We isolated immunoglobulin G (IgG) from these antibodies and injected iv into male ddy mice. Control mice were injected iv with bTSH or TSAb-negative normal rabbit IgG. Serum T3 and T4 concentrations were elevated after the administration of bTSH in a dose-dependent manner. Serum T3 and T4 concentrations were significantly elevated after the injection of IgG from the rabbit antibodies with TSAb activity produced against TSH-R-HIS17. However serum T3 and T4 remained within normal levels after the injection of IgG from the rabbit antibodies without TSAb activity toward TSH-R-ASP17. The present data offer in vivo support of the IgG with TSAb activity interaction with the TSH receptor of the thyroid and raise the possibility that TSAb against mutated human TSH receptor peptide might be contributed to induce thyroid hyperfunction.

Amino Acid Sequence↗