Biomedical subjects

H Azuma

Publications and source records attributed to H Azuma.

At least 199 records · Page 11Linked to original sources

PubMed1993

Disulfide bond requirements for assembly of the platelet glycoprotein Ib-binding domain of von Willebrand factor.

von Willebrand factor (vWF) is a multimeric glycoprotein of plasma and the subendothelial matrix that interacts with specific platelet receptors to establish platelet adhesion at a site of vascular injury. The vWF domain containing the platelet receptor glycoprotein Ib-binding site can be expressed in heterologous cells as a recombinant homodimeric fragment that mediates platelet-platelet interaction, analogous to multimeric vWF. The recombinant domain, r116, contains 7 Cys residues within its 290-residue monomeric subunit paired in an unidentified intra- and intermolecular disulfide bond arrangement. In this report we define the disulfide bond-dependent framework of r116 that provides the domain with its essential structural features that support dimer formation and the generation of a disulfide bond-dependent epitope. The results demonstrate that a triplet of Cys residues at positions 459, 462, and 464 are essential for efficient dimer formation. An intramolecular Cys509/Cys695 disulfide loop is required for generating a functional dimeric molecule, and monomeric molecules containing a Cys509/Cys695 intramolecular disulfide bond are unable to support ristocetin-mediated platelet aggregation. The disulfide arrangement in r116 is similar, if not identical, to the proposed arrangement within the corresponding region of plasma vWF, and these studies document the inherent Cys-dependent maturation of an isolated vWF domain.

Disulfides↗

PubMed1993

A role for von Willebrand factor proline residues 702-704 in ristocetin-mediated binding to platelet glycoprotein Ib.

Mutant domains of von Willebrand factor (vWF) were constructed to determine the effects of altering net charge, and presumably conformation, within a peptide sequence (residues 694-708) previously shown to be involved in the platelet receptor glycoprotein (GP) Ib binding function of vWF. Non-conservative substitutions replaced a triplet of proline residues (proline702-704) with either a triplet of arginine (positively-charged) or aspartic acid (negatively-charged) residues. After establishing stable CHO cell transformants, we observed the secretion of covalently-linked dimeric molecules analogous to a domain with native sequence. Functional assays using immunopurified molecules revealed that the ristocetin-dependent binding to GP Ib was abolished with both charge mutants. However, in the absence of disulfide-bond dependent conformation both mutant molecules and the molecule with native sequence interacted with GP Ib. The results demonstrate that vWF proline702-704 are important for the ristocetin-mediated interaction between vWF and GP Ib, but are not essential residues of the GP Ib binding site within vWF.

Amino Acid Sequence↗

PubMed1993

Intimal hyperplasia enhances myosin phosphorylation in rabbit carotid artery.

We examined physiological events in the hyperplastic artery, using a method based on the mechanical responsiveness and myosin light-chain phosphorylation in response to various stimulants. Six weeks after endothelial denudation by ballooning of the right carotid artery, strips of this artery with moderate intimal hyperplasia (intimal area was 30-50% of medial area in 20 of 28 rabbits) were used for experiments. Strips from the left carotid served as the normal control. When the hyperplastic artery was stimulated with 30 microM PGF2 alpha, the maximal tension (232.4 +/- 49.1 mg/mg dry wt, mean +/- SD) was significantly higher (P < 0.05) than that of the control (129.5 +/- 16.4 mg/mg). The maximal extent of myosin light-chain monophosphorylation (45.4 +/- 8.9%) and diphosphorylation (10.9 +/- 5.2%) in the hyperplastic artery was significantly higher (P < 0.05) than that in the control artery (33.0 +/- 4.8 and 4.0 +/- 4.8%, respectively). The monophosphorylation of the myosin light chain in the hyperplastic artery was sustained for up to 20 min, while that in the control artery decreased to the basal level within 20 min. Similar observations were obtained by stimulation with 60 mM K+ or 30 microM norepinephrine. Dose-response curves of the development of tension in the hyperplastic artery to various agonists (K+, PGF2 alpha, norepinephrine) shifted upward the curves for the control artery. These results suggest that qualitative changes in the characteristics of smooth muscle cells may occur in the intimal hyperplastic portion, including a hyperreactive contraction associated with enhanced and sustained phosphorylation of the myosin light chain.

Animals↗

PubMed1993

Effect of interleukin 2 on intractable herpes virus infection and chronic eczematoid dermatitis in a patient with Wiskott-Aldrich syndrome.

Recombinant interleukin 2 (rIL2) was administered to a patient with Wiskott-Aldrich syndrome for the treatment of an intractable facial herpetiform lesion. This treatment appeared to be effective in suppressing the virus activity. At the same time, a transient improvement of the chronic eczematoid dermatitis was observed. During rIL2 administration, the CD3+ and CD4+ subsets of peripheral blood lymphocytes increased in number. These changes might play an important role in the induction of anti-viral immunity and in the improvement of dermatitis.

CD3 Complex↗

PubMed1993

[Effect of high-dose gammaglobulin on a case of Guillain-Barré syndrome].

We reported an infant case of Guillain-Barré syndrome treated with high-dose gammaglobulin. Gammaglobulin was given at a dose of 1 g/kg/day for 2 consecutive days. Dyspnea disappeared six hours after the start of the infusion. The patient was able to sit 3 days and walk alone 25 days after the end of therapy. Circulating immune complexes were 48 micrograms/ml before the therapy, 95 micrograms/ml and 39 micrograms/ml 10 days and 37 days, respectively, after the therapy.

Antigen-Antibody Complex↗

PubMed1993

Age-related alterations in receptor density and metabolic activity in the brain.

The present experiments were designed to investigate whether or not age-related changes in brain function became detectable by comparing the responsiveness to stimulants or blocking agents between young and relatively aged rats. Oxygen consumption by hippocampal slices under the resting condition (3.5 mM KCl) was not significantly altered by aging (between 26 and 78 wk of age). When KCl concentration was increased to 50 mM, oxygen consumption by the slices from both young and aged groups significantly increased, but the increase was significantly greater in slices from young rats. Enzyme activities of the glycolytic pathway as well as a non-energy metabolizing enzyme, choline acetyltransferase, were not different between 6 and 26 wk of age. [3H]Prazosin binding in the cerebral cortex tended to be lower in the aged (78 wk old) rats but not significantly different from that in the young (13 wk old) ones. On the other hand, the recovery from the reduced prazosin binding following administration of phenoxybenzamine was significantly delayed in the aged rats. These results indicate that the age-related changes in brain function become evident by comparing the responsiveness to stimulants or blocking agents between young and aged rats.

Aging↗

PubMed1993

Osteosarcoma of the patella. A case report.

A 34-year-old woman complained of pain and swelling in the left patella. Because of roentgenogram showed hardly any destruction of the patella, she was not initially treated for a bone tumor. The clinical course followed the initial symptoms of a respiratory disorder with pulmonary metastatic foci. A bone tumor was first suspected after aspiration cytology of a lung tumor mass. A left patellectomy was performed to relieve the pain and confirm the diagnosis. The pain was relieved by the operation, but respiratory failure set in and progressed rapidly. The patient died three days later. Histologic examination showed that the tumor tissue consisted of atypical cells, spindle to polygonal in shape. The marrow space of the patella was predominantly occupied by neoplastic cartilaginous tissue. The pathologic diagnosis was primary chondroblastic osteosarcoma of the patella.

Adult↗

PubMed1992

Cytochrome b positive X-linked chronic granulomatous disease: a normal cell surface expression of cytochrome b.

The polymorphonuclear (PMN) cells from a patient with cytochrome b positive X-linked chronic granulomatous disease (Xb+ CGD) were studied using flow cytometry. Both the cell surface expression of monoclonal antibody defined cytochrome b and the superoxide production (intracellular 2',7'-Dichlorofluorescin Diacetate oxidation) were investigated at a single cell level. Flow cytometry clearly demonstrated the complete absence of superoxide production in the patient's PMN cells, the mosaicism in his mother's PMN cells and also indicated the normal cell surface expression of cytochrome b. The results obtained by Western blot analysis and reduced-minus-oxidized spectra confirmed the presence of functional and normal amounts of cytochrome b. We concluded that this is a case of Xb+ CGD with a normal cell surface expression of cytochrome b.

Adolescent↗

PubMed1992

Melorheostosis of the hand: a report of two cases.

Two cases of melorheostosis of the hand are reported. Histopathologic examination confirmed the characteristic x-ray findings and excluded other skeletal dysplasias, such as osteopoikilosis and osteopathia striata.

Adult↗

PubMed1992

Maternal responsiveness to infants in three societies: the United States, France, and Japan.

This study examines and compares prominent characteristics of maternal responsiveness to infant activity during home-based naturalistic interactions of mother-infant dyads in New York City, Paris, and Tokyo. Both culture-general and culture-specific patterns of responsiveness emerged. For example, in all 3 locales infants behaved similarly, mothers also behaved similarly with respect to a hierarchy of response types, and mothers and infants manifest both specificity and mutual appropriateness in their interactions: Mothers responded to infants' exploration of the environment with encouragement to the environment, to infants' vocalizing nondistress with imitation, and to infants' vocalizing distress with nurturance. Differences in maternal responsiveness among cultures occurred to infant looking rather than to infant vocalizing and in mothers' emphasizing dyadic versus extradyadic loci of interaction. Universals of maternal responsiveness, potential sources of cultural variation, and implications of similarities and differences in responsiveness for child development in different cultural contexts are discussed.

Adult↗

PubMed1992

Prevention of intimal thickening after endothelial removal by a nonpeptide angiotensin II receptor antagonist, losartan.

1. The present experiments were designed to investigate the role of local angiotensin II receptors in the myointimal proliferative response of the vascular wall after endothelial removal, by use of a novel, nonpeptide, angiotensin II receptor antagonist, losartan. 2. When administered 1 week before endothelial removal from the rabbit carotid artery and then continuously until animals were killed 6 weeks later, losartan in a dose of 10 mg kg-1 daily, p.o. had no significant effects on the carotid blood flow (CBF), mean arterial blood pressure (MBP) and heart rate (HR). 3. A full endothelial lining with increased density of regenerated endothelial cells was observed 6 weeks after the endothelial removal. These changes were unaffected by treatment with losartan. 4. Six weeks after endothelial removal, acetylcholine (ACh)- and adenosine diphosphate (ADP)-induced relaxations were greatly reduced though endothelial cells had regenerated. The reduction of the relaxations to these agonists were significantly restored by chronic treatment with losartan. The endothelial-independent, sodium nitroprusside (SNP)-induced relaxation remained unaffected in all groups. 5. There were no differences in the noradrenaline (NA)- and endothelin-1 (ET-1)-induced contractions of the carotid artery strips between vehicle and losartan-treated groups. In contrast, the contractile response of the strips to angiotensin II was significantly decreased in the losartan group, indicating the specific antagonism by chronic losartan against the angiotensin II receptor. 6. Six weeks after endothelial removal, marked myointimal proliferation resulting from new accumulation of proliferating smooth muscle cells and connective tissue was observed in the vehicle group. Losartan treatment greatly suppressed the myointimal proliferative response.7. These results suggest that the local angiotensin II receptors play a role in the myointimal proliferativeresponse of the vascular wall to removal of the endothelium.

Acetylcholine↗

PubMed1992

A possible role of decreased relaxation mediated by beta-adrenoceptors in bladder outlet obstruction by benign prostatic hyperplasia.

1. To explore mechanisms of urinary obstruction in benign prostatic hyperplasia (BPH), the features of contraction and relaxation in human hyperplastic and non-hyperplastic (control) prostatic tissues were investigated for beta- and alpha 1-adrenoceptors by radioligand binding and in vitro isometric tension experiments. 2. Hyperplastic and control prostatic tissues had a similar number (per mg protein) of prazosin binding sites with similar affinities. Noradrenaline (NA) induced dose-dependent contraction in both tissues. Contraction induced by either exogenous NA or transmural stimulation was inhibited by prazosin in both tissues, indicating that the same contractile mechanisms mediated by alpha 1-adrenoceptors exist in hyperplastic and control tissues. 3. The number of dihydroalprenolol (DHA) binding sites (per mg protein) was less in hyperplastic tissues than in controls, whereas the affinity to the ligand was identical in both tissues. Isoprenaline caused a marked relaxation of the tonic contraction induced by KCl in control tissues, but not in hyperplastic tissues. Propranolol enhanced exogenous NA- or transmural stimulation-induced contraction more in control tissues than in hyperplastic tissues. Both tissues, however, similarly responded to forskolin by relaxation. 4. These results indicate that decreased beta-adrenoceptor-mediated relaxation in hyperplastic prostatic tissues, which is attributable at least in part to the decreased number of beta-adrenoceptors, may play a role in the urinary obstruction of BPH in addition to mechanical compression of the urethra by the enlarged prostate.

Adult↗

PubMed1992

An increased ability to generate hydrogen peroxide in certain polymorphonuclear leukocytes in neonates.

We performed a quantitative assay of the hydrogen peroxide generation in polymorphonuclear leukocytes using single cell analysis by flow cytometry. The study population included premature neonates (n = 10), term neonates (n = 28) and healthy adults (n = 29). The ability to generate hydrogen peroxide in neonatal polymorphonuclear leukocytes was totally reduced compared with adults, however, some polymorphonuclear leukocytes in neonates demonstrated highly accentuated hydrogen peroxide generation.

Adult↗

PubMed1992

[Malignant mesodermal mixed tumor of the bladder: report of a case].

A 59-year-old male took total cystourethrectomy on July, 1991, since the bladder tumor recurred 2 years and 4 months after transurethral resection. Six months after total cystourethrectomy, an abnormal mass shadow appeared on the right lower lung field. Metastatic lung tumor was strongly suspected from CT scan. Despite chemotherapy, the pulmonary lesion grew rapidly and the patient died. From the autopsy, metastatic lesions were found in the bilateral lung fields, skin (face, head and abdominal wall), pleura, bilateral kidneys, small intestine and lymph nodes (para-aortic and mesenteric). The primary bladder tumor contained histologically transitional cell carcinoma as the epithelial element and sarcomatous changes with osteoid formation as the non-epithelial elements. Thus, the primary lesion was diagnosed as a malignant mesodermal mixed tumor. However, all of the metastatic lesions showed only sarcomatous changes. Only 10 cases of malignant mesodermal mixed tumor of the bladder have been reported in Japan since Fujita's report. In general, total cystectomy is necessary for the treatment of this disease. It has a poor prognosis; 5 of the 10 patients died within one year after operation.

Humans↗

PubMed1992

[Hypothyroidism followed by interferon-alpha as adjuvant therapy of renal cell carcinoma: a case report].

A 58-year-old male patient was admitted to the hospital complaining of weight loss. Abdominal computerized tomographic (CT) scan disclosed a mass shadow in the left kidney. From the results of further examination, including drip infusion pyelography (DIP) and angiography, he was preoperatively diagnosed as having a left renal tumor. Left radical nephrectomy was performed on March 15, 1990. The lesion was histologically diagnosed as renal cell carcinoma (clear cell subtype, grade 2) confined by the renal capsule (stage I). No distant metastases were detected. Interferon-alpha was administered every other day as adjuvant chemotherapy. After the patient experienced muscle pain in his thighs and shoulders after exercise on February 11, 1991, the serum creatine phosphokinase (CPK) level progressively increased up to 2,329 U/l. On the basis of the results of various examinations reflecting thyroid gland function, he was diagnosed as having primary hypothyroidism due to Hashimoto's disease. Thyroid function improved after administration of triiodothyronine and thyroxine. Interferon has been reported to influence thyroid function, and, in this case, interferon-alpha therapy may have induced the primary hypothyroidism associated with Hashimoto's disease.

Chemotherapy, Adjuvant↗

PubMed1992

Aminophylline suppository-induced acute proctitis.

A 9-yr-old boy revealed anal hemorrhage after administration of an aminophylline suppository. Proctosigmoidoscopy demonstrated edema of the rectal mucosa with hyperemia and petechiae. We performed a provocation test and obtained the diagnosis of aminophylline suppository-induced acute hemorrhagic proctitis. One should recognize that acute hemorrhagic proctitis is a rare but important side effect of aminophylline suppositories, because they are commonly used for asthmatic children.

Acute Disease↗

PubMed1991

Effect of bright light in the morning on diurnal variations of pineal indoles in NZBWF1 mice.

Exposure to bright light (2000 lx) for 2 h at the beginning of a 12 h light period (10 lx) resulted in about 1 h advances in the onset and termination of N-acetylserotonin (NAc5HT) synthesis in the pineal gland of NZBWF1 strain mice compared with those in mice not exposed to bright light. These effects are in contrast with the effect of exposure to bright light throughout the light period, which delayed the onset of pineal NAc5HT synthesis in NZB mice. The possible relationship of these effects with the mechanism of action of phototherapy of human affective disorder is discussed.

Animals↗

PubMed1991

Independent assembly and secretion of a dimeric adhesive domain of von Willebrand factor containing the glycoprotein Ib-binding site.

von Willebrand factor (vWF) is a multimeric glycoprotein that supports platelet adhesion on thrombogenic surfaces as part of the normal hemostatic response to vascular injury. We have employed a domain-specific expression strategy to analyze the biosynthetic processing steps and minimum structural requirements for assembly of the platelet receptor glycoprotein Ib-binding domain of vWF. A chimeric cDNA that codes for the vWF signal peptide and a segment of vWF internal primary sequence, residues 441-730, directs the secretion of a functional vWF fragment from mammalian cells. The recombinant molecule intrinsically assembles through intermolecular disulfide bond formation into a dimeric adhesive domain without contributions from other regions of vWF, including propeptide, previously indicated as essential for vWF multimer assembly. Prevention of N-linked glycosylation on the recombinant domain does not impair dimer formation or the ability to support platelet aggregation. These results identify a minimum structural element for vWF subunit assembly and provide new insights into the processing steps to produce vWF multimers and adhesive domains.

Animals↗