Biomedical subjects

K Kamiya

Publications and source records attributed to K Kamiya.

At least 163 records · Page 9Linked to original sources

PubMed1995

Effect of chronic hypoxia on ion channel development in cultured cardiac cells.

In order to investigate mechanisms underlying the postnatal development of the transient outward current (Ito) in the rat heart, we established a primary culture of neonatal rat ventricular myocytes and studied the modulated expressions of Ito under normoxic (21% O2) and hypoxic (7.5% O2) growth conditions. During development from day 5 to day 15 in the normoxic cultures, Ito density doubled without any changes to the kinetics of current inactivation. Chronic hypoxia from day 6 to day 15 prevented this increase in Ito density. The reduced expression of Ito under hypoxic conditions was due to the loss of the fast inactivating component of Ito (Ito,f) These observations suggest that ion channels in neonatal rat cardiomyocytes in primary culture are not constitutively expressed but can be regulated by extrinsic factors. The postnatal increase in Ito density among newborn rats is closely associated with an alteration in oxygen tension.

Action Potentials↗

PubMed1995

Effects of stress on Kv1.5 K+ channel gene expression in the left ventricle of rat hearts.

Voltage-dependent K+ channels contribute to the repolarization phase of the cardiac action potential. An increase in Kv1.5 K+ channel gene expression by a pharmacological dose of glucocorticoid was reported recently in the heart of an adrenalectomized rat. In this study, we examined whether physiological elevations of glucocorticoid induced by tail suspension affects the K+ channel gene expression. Five-week-old male Wistar rats were subjected to tail suspension for three days. Total RNA was extracted from the ventricle, and the level of Kv1.5 mRNA was determined by Northern blot analysis. On the first day, the Kv1.5 mRNA had increased over the non-suspended rat. By the third day, mRNA had increased significantly by more than 3-fold. knowing that urinary excretions of glucocorticoid increase in tail-suspended rats, these findings suggest that physiologically elevated glucocorticoid may upregulate Kv1.5 K+ gene expression.

Action Potentials↗

PubMed1995

[Exposure to blood during midwifery procedures--blood contact events to midwives occurred in a delivery room].

Midwives are often exposed to blood during delivery procedures. A study aimed at clarifying actual status of blood contact during midwifery procedures was performed. Observations in a delivery room were conducted to record blood contact events experienced by midwives from the time of episiotomy until 2 hour after expulsion of the placenta. All gloves used by midwives were collected and tested for holes. Blood contact was defined as any contact with blood of a parturition woman as recognized visually by an observer. During a one-month study period data was obtained from a total of 19 midwives (12 midwives and 7 student midwives) who assisted in 8 deliveries. All of the midwives wore gowns with long sleeves, gloves and caps but did not use eye protection or masks. None of the parturient women had Hepatitis B, Hepatitis C or acquired immunodeficiency syndrome. Deliveries caused widespread blood exposure to the midwives throughout the complete course. Protection from most of this exposure was provided by the gowns and gloves. However, direct blood contacts occurred to the fingers, hands or forearms in several midwives. These events were caused by partly because the midwives unintentionally performed procedures without gloves and partly because blood penetrated the gown and soaked to the skin. Direct blood contacts to the foot in two midwives and to the mouth in one also occurred. The overall perforation rate for gloves examined was 4 out of 154 (2.6%). Two gloves were broken during washing sharp instruments contaminated with blood, one was torn when wearing, and the remaining one appeared to have had a hole prior to use.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

[Exposure to blood during midwifery operations--a questionnaire study].

A self-administered questionnaire was mailed to all midwives working in Nara Prefecture to investigate blood exposure events at delivery and to consider protective measures for the exposure. Out of the 203 midwives 193 responded to the questionnaire. The median number of deliveries in which the midwives had assisted within the past one year was 35 after excluding those who had not assisted in deliveries at all. The incidence of needle-stick injuries was estimated to be 86.2 per 100 persons within the past one year. The occurrence in the subgroup who had worked as midwife for less than 5 years was 2-3 times higher than that in those who worked for more than 5 years. Over 90% of the midwives had experiences of direct blood contact events to the skin while assisting in their 10 most recent deliveries. Blood contact events occurred in the finger-hand-arm area in 85% of the midwives, on the legs in 62%, in the face in 20% and in the eyes in 1%. Around 20% of the midwives had unintentionally sucked amniotic fluid when using a tracheal catheter on a newborn. The most common occasion where direct blood contact events occurred was while bathing an infant for removing blood and amniotic fluid. The midwives wore a disposal gown more often when assisting in labors of parturient women infected with blood-born infectious diseases than without the diseases, and similarly for wearing gloves when measuring blood loss and for usage of a mechanical device for sucking amniotic fluid in the tracheae of an infant. Based on the results obtained in this questionnaire study and our previous study about blood contact events observed in a delivery room, protective measures for midwives against exposure to blood at delivery are required and some ideas are presented.

Accidents, Occupational↗

PubMed1994

A simple luminescence method for detecting lipid peroxidation and antioxidant activity in vitro.

The excited carbonyl species formed during lipid peroxidation may transfer their energy to dye molecules containing heavy atoms such as rose bengal to produce excited singlet state dye molecules. The excited dye then emits photons to return to its ground state. The aim of the present study was to investigate the relationship between methemoglobin (metHb)-induced lipid peroxidation, rose bengal luminescence, and O2 consumption in a system containing 0-850 mu M phospholipid and 1 mu M metHb and 1 mu M rose bengal in Tris-HCl buffer, pH 7.4. The rapid rise in rose bengal luminescence was accompanied by a rapid rise in O2 consumption. Further, the luminescence of rose bengal could be quenched by alpha -tocopherol or probucol present in the phospholipid liposomes, with the latter being strikingly more effective than the former. This simple luminescence method is a useful practical approach to detect lipid peroxidation and determined antioxidant effects of water insoluble compounds in vitro.

Antioxidants↗

PubMed1994

Clinical pharmacology of 1-beta-D-arabinofuranosylcytosine-5'-stearylphosphate, an orally administered long-acting derivative of low-dose 1-beta-D-arabinofuranosylcytosine.

1-beta-D-Arabinofuranosylcytosine-5'-stearylphosphate (cytarabine ocfosfate, stearyl-ara-CMP) is a newly synthesized 5'-alkylphosphate derivative of 1-beta-D-arabinofuranosylcytosine (ara-C), which is lipophilic, resistant to inactivation by deamination, and orally active. Pharmacology of this drug was studied in patients with hematological malignancies. The concentrations of stearyl-ara-CMP, ara-C (its active metabolite), and 1-beta-D-arabinofuranosyluracil (ara-U, its inactive metabolite) were determined by radioimmunoassay. When six patients received a single p.o. dose of the drug (500 mg/m2), stearyl-ara-CMP, ara-C, and ara-U could be detected in the plasma for at least 72 h afterwards. The plasma disappearance curve of stearyl-ara-CMP corresponded to a one-compartment open model with first-order absorption kinetics. The peak plasma level (Cmax) was 322 +/- 218 nM, and the predicted time to reach Cmax (Tmax) was 6.5 +/- 4.5 h, while the elimination half-life (t1/2) was very long (32.0 +/- 8.4 h). The plasma ara-C level increased slowly to a Cmax of 26.3 +/- 12.7 nM (Tmax, 13.3 +/- 4.7 h) after stearyl-ara-CMP administration. This level was quite low compared with that achieved by low-dose s.c. ara-C therapy, but ara-C persisted longer in the plasma in the former case, and the area under the curve was similar for both regimens. For ara-U, the Cmax, Tmax, and t1/2 were 483 +/- 315 nM, 23.6 +/- 4.0 h, and 19.6 +/- 5.3 h, respectively. No stearyl-ara-CMP was detected in the urine, and only 8.0% of the administered dose was excreted as ara-C and ara-U within 72 h. The stearyl-ara-CMP concentration in the cerebrospinal fluid was below the limit of detection in three patients without meningeal involvement at 6 h. During clinical use of stearyl-ara-CMP, macrocytic anemia was observed, and some patients also developed megaloblastic change of their erythroblasts, suggesting a mild and persistent cytostatic effect. In conclusion, p.o. therapy with stearyl-ara-CMP achieved prolonged maintenance of the plasma drug level. Thus, the drug released a very low dose of ara-C over a long period in plasma and tissues and had a prolonged mild antineoplastic effect in patients with hematological malignancies.

Acute Disease↗

PubMed1994

Ca(2+)-calmodulin mediated modulation of the electrical coupling of ventricular myocytes isolated from guinea pig heart.

The mechanism for the regulation of junctional conductance (gj) by Ca2+ was examined in paired ventricular myocytes isolated from guinea pig heart. One cell of the pair was voltage-clamped by a single-patch pipette, and gj was measured after perforation of the non-junctional membrane of the partner cell. The average value of gj under control condition at pCa 9.0 was 181 +/- 13 nS (n = 30). An elevation of calcium concentration ([Ca2+]i) in the intracellular perfusate from pCa 9.0 to pCa 5.7 resulted in a decrease of 32 +/- 5% in gj (n = 18). In myocytes pretreated with W7 (10(-4) M), a similar elevation of [Ca2+]i caused a decrease of only 10 +/- 3% in gj (n = 6), indicating a protective action of W7 against Ca(2+)-mediated electrical uncoupling. W5 (10(-4) M), a non-chlorinated derivative of W7, did not show such a protective action. Calmodulin (10(-5) M) had no effects on gj at pCa 9.0. However, at moderately elevated [Ca2+]i condition at pCa 7.0, calmodulin (10(-5) M) decreased gj by 29 +/- 6% (n = 4). These results suggest that calmodulin may play an important role in the Ca(2+)-mediated regulation of gap junctional channel function in the cardiac ventricular cells.

Action Potentials↗

PubMed1994

Distal arterial reconstruction using Esmarch's bandage technique to salvage upper extremity function in thoracic outlet syndrome caused by cervical ribs: a report of two cases.

We present herein the cases of two patients with thoracic outlet syndrome (TOS) who required arterial reconstruction due to gangrene of the fingers and/or hand. In both patients, the cervical ribs had produced intimal injury of the subclavian arteries, and the successive distal arterial embolism brought about severe ischemia of the affected upper extremity. To treat the TOS, the cervical ribs were resected through a supraclavicular incision. In the first patient, arterial reconstruction was performed from the subclavian artery to the radial collateral artery, a branch of the deep brachial artery, which resulted in minimizing amputation of the gangrenous hand. In the second patient, resection and direct anastomosis of the injured subclavian artery were performed, and bypass surgery from a brachial artery to an interosseous artery was carried out, preserving finger function. Reversed saphenous vein grafts were utilized and Esmarch's bandage technique was applied as a substitute for a vascular clamp in both patients. Following these case reports, we discuss the technique of performing distal bypass in the upper extremities and comment on the usefulness of Esmarch's bandage technique for preserving upper extremity function.

Adult↗

PubMed1994

Peripheral anterior inferior cerebellar artery aneurysms.

Two cases of peripheral anterior inferior cerebellar artery (AICA) aneurysms are reported. The first case was a 60-year-old man who showed frequent attacks of subarachnoid hemorrhage (SAH) and hearing disturbance. His aneurysm was obliterated by trapping the AICA and his neurologic status was unchanged compared with preoperatively. The second case had SAH without cranial nerve involvement; this aneurysm was obliterated by neck clipping. He was discharged without neurologic deficit. Peripheral AICA aneurysm has already been reported in 48 cases including arteriovenous malformation-associated cases. This aneurysm may show cranial nerve involvement (seventh and eighth) without SAH as in the case of internal carotid-posterior communicating artery aneurysms. We review the clinical signs of these cases and discuss them from the point of view of anatomic variations of the AICA and internal auditory artery.

Aged↗

PubMed1994

Radiation induction of germline mutation at a hypervariable mouse minisatellite locus.

Paternal 60Co gamma-irradiation was tested for the induction of germline mutation at the mouse hypervariable minisatellite locus, Ms6hm. Male C3H/HeN mice were exposed to 3 Gy 60Co gamma-ray and mated with C57BL/6N females. Matings were made at 1-7, 15-21 and 71-77 days post-treatment to test spermatozoa, spermatids and spermatogonia stages. Reciprocal crosses were also made with irradiated C57BL/6N males. Southern analysis was carried out on DNA from parents and F1 mice. The paternal mutation frequencies per gamete of the Ms6hm locus were 8.3, 13, 28 and 15% for the C3H/HeN control, exposed spermatozoa, spermatids and spermatogonia stages, respectively. The paternal mutation frequencies per gamete were 7.7% for the C57BL/6N control and 13% for the C57BL/6N exposed spermatozoa stage. The increase in the paternal germline mutation frequency was statistically significant for C3H/HeN spermatids irradiation (p < 0.005). The induced mutation frequencies were of the order of 10(-1), and was too high to be accounted for by the direct action of radiation on the locus. These results suggest the presence of a previously unexpected mechanism of radiation induction of germline mutation. In addition, we demonstrate that the hypervariable minisatellite locus can serve as a sensitive monitor for genetic damages to germline cells.

Animals↗

PubMed1994

Factor IX Bm Kiryu: a Val-313-to-Asp substitution in the catalytic domain results in loss of function due to a conformational change of the surface loop: evidence obtained by chimaeric modelling.

Factor IX Kiryu is a naturally occurring mutant of factor IX that has 2.5% coagulant activity, even though normal plasma levels of factor IX antigen are detected. Factor IX Kiryu was purified from a patient's plasma by immunoaffinity chromatography with a calcium-dependent anti-factor IX monoclonal antibody column. It was cleaved normally by factor XIa in the presence of Ca2+, yielding a two-chain factor IXa. However, the resulting factor IXa showed only 1.5% of the normal factor IXa in terms of factor X activation in the presence of factor VIII, phospholipids, and Ca2+, and had 20% of the normal esterase activity for Z-Arg-p-nitrobenzyl ester. Therefore factor IXa Kiryu showed the defect of the catalytic triad or primary substrate binding site as well as defective interaction with factors VIII/X. Single-strand conformational polymorphism analysis and DNA sequencing of the amplified DNA revealed a missense point mutation, a T-to-A substitution at nucleotide number 31,059 of the factor IX Kiryu gene. This mutation resulted in the amino acid substitution of Val-313 by Asp in the catalytic domain. Restriction enzyme analysis of the amplified DNA showed that the mutation was inherited from the patient's mother. The chimaeric method was employed to construct a model of the serine protease domain of factor IXa, and the resultant model suggested that the Val-313 to Asp substitution altered the conformation of the substrate-binding site. These data combined with our previous findings on a Gly-311-to-Glu mutant of factor IX suggest that the loop conformation from Gly-311 to ARg-318 is important for the expression of coagulant activity.

Amino Acid Sequence↗

PubMed1994

West syndrome associated with porencephaly.

A 3-year-old boy with West syndrome who was shown to have a cystic lesion on magnetic resonance imagings underwent surgical treatment. He had been initially managed with several antiepileptic drugs, but abnormalities on electroencephalography (EEG) persisted. Histological examination of the cystic wall obtained during surgery suggested porencephaly. Two years and 2 months later the child remained seizure-free and his EEG remarkably improved.

Adrenocorticotropic Hormone↗

PubMed1994

Nature of protein adsorption in artificial tear solution on plasma-irradiated polymethylmethacrylate surface.

To evaluate the effect of plasma treatment on protein adsorption onto a polymer surface, we carried out Ar plasma irradiation on polymethylmethacrylate (PMMA) plate and examined the adsorption behavior of protein after immersion of plasma treated PMMA plate in the artificial tear solution containing lysozyme, albumin and gamma-globulin. It was found that the total adsorption of protein in the artificial tear solution to PMMA is suppressed by the Ar plasma treatment. But the adsorption of each component protein differs according to the surface condition of polymers and obviously corresponds to the change with time in the surface wettability. It is concluded that introduction of a hydrophilic group into the PMMA surface by plasma treatment and coming off of it are associated with the adsorption behavior of proteins. Since the adsorption of protein to the plasma-treated PMMA surface changes over time, care should be exercised in determining it, when an attempt is made to clarify the effect of plasma irradiation on the adsorption to the plasma-irradiated polymer surface.

Adsorption↗

PubMed1994

Three-dimensional model of the human PAF receptor.

The amino acid sequence analysis of the human platelet-activating factor (PAF) receptor showed that residues thought to be important structurally and functionally were well conserved. This suggested similarities of the three-dimensional structure (3D structure) between the human PAF receptor and other receptors that couple to guanine nucleotide binding (G) proteins. Thus, a three-dimensional model of this receptor was constructed using the 3D structure of bacteriorhodopsin as the reference protein, by means of the BIOCES[E] computer-modeling system. This model has seven alpha-helical transmembrane segments which form a central core and an S-S bond between the second and third extracellular loops. The distance of the S-S bond is about 2 A, which is thought to be reasonable. In the transmembrane domain, the side chains of Asp-63, Asn-285 and Asp-289 became oriented toward the central core and form a negatively charged site. This receptor model suggests that the positively charged choline moiety of PAF is attracted to this negatively charged site by electrostatic forces and that PAF may induce conformational changes in the receptor, leading to G-protein activation.

Amino Acid Sequence↗

PubMed1994

[An evaluation of the hemodynamics in metastatic liver tumor by using ultrasound color Doppler flow mapping examination].

Eighty-one patients with metastatic liver tumors were studied by ultrasound color Doppler flow mapping examination. Primary origins consisted of gastric (19 cases), colorectal (40 cases), breast (7 cases), pancreatic (3 cases), gallbladder (3 cases) cancers and the others (9 cases). Metastatic lesions originated from breast, gastric and colorectal cancers had higher detection rates, however no blood flow could be observed within metastatic liver cancers from pancreatic and gallbladder cancers. There were no differences among the maximum blood flow velocity (Vmax), the resistance index (RI) and the pulsatile index (PI) in various metastatic liver tumors. In case of colorectal cancers, metastatic lesions originated from moderately differentiated adenocarcinoma had significantly lower RI (p < 0.05) and PI (p < 0.01) than that from well differentiated adenocarcinoma. In conclusion, ultrasound color Doppler flow mapping examination is a useful method for evaluation of the blood flow within metastatic liver tumors and could offer the histological differentiation of the primary origins, in case of metastatic liver cancers originated from colorectal cancers.

Adult↗

PubMed1994

[Risk factors for neonatal and postneonatal mortality--a record-linkage study based on vital statistics].

This study examines the effects of biological, demographic and social variables, as reported on birth certificates, on neonatal and postneonatal mortalities. Examination of both birth and infant death certificates was performed for infants born in 1989 to residents of Tohoku, Tokai and Kyushu regions (n = 409,679), i.e. about a third of the total number of infants born in Japan. Record linkage rates in the neonatal and postneonatal periods were 99% and 92% respectively. The neonatal and postneonatal mortality rate of the cohort including unlinked deaths were 2.65/1,000 live-born infants and 2.02/1,000 neonatal survivors respectively. Both neonatal mortality rate and postneonatal mortality rate increased exponentially as birth weight decreased. Infant's sex and gestational period exerted significant influences on neonatal mortality after controlling for birth-weight by logistic regression. However, no overall effect on neonatal mortality was seen for maternal age, live-birth order, previous stillbirths and marital status, when birth-weight was taken into account. This suggests that the effect of social-demographic disadvantage on neonatal mortality is predominantly mediated through a downward shift in the birth-weight distribution. On the other hand, postneonatal mortality was influenced substantially by socio-demographic factors. Maternal age of less than 20 years and more than 35 years, one or more previous live-birth and unmarried marital status were all significantly related to increased risk of postneonatal death after controlling for birth-weight. Occupational type classification of the household, also, had a significant effect on postneonatal mortality, with agriculture, self-employed, or blue collar employee being related to increased risk.

Birth Weight↗

PubMed1994

[Atheromatous embolization as a cause of postoperative renal dysfunction in infrarenal aortic reconstructive surgery].

Influences of atheromatous changes in the aortic wall at the site of proximal clamping were studied retrospectively on postoperative renal function in an infrarenal aortic reconstruction. Atheromatous lesion was evaluated on CT scan as low density layer in the aortic wall observed in cases with the thickened wall exceeding 3mm, and they were classified into atheromatous group (group II) consisted of 21 patients. In these patients, the postoperative serum creatinine showed significant elevation from preoperative value of 0.89 +/- 0.32 mg/dl to 1.67 +/- 0.90 mg/dl on 1st postoperative day (p < 0.01), 1.25 +/- 0.99 mg/dl on 7th day (p < 0.05) and 1.24 +/- 0.89 mg/dl on discharge (p < 0.05). Correlation between the severity of the postoperative renal dysfunction and the degree of the atheromatous changes evaluated by preoperative CT scan was also defined and 2 patients with severe changes died of acute renal failure. On the contrary, 39 patients without thickened wall (group I) showed no significant elevation of serum creatinine after operation. These results strongly suggest that atheromatous embolization to the kidney plays an important role to cause postoperative renal impairment following infrarenal aortic reconstructive surgery for the patients with atheromatous changes in the aorta near the site of proximal clamping.

Acute Kidney Injury↗

PubMed1993

Transcriptional repressor ZF5 identifies a new conserved domain in zinc finger proteins.

We have cloned a cDNA encoding a new murine C2H2 zinc finger protein, ZF5. The 51.3 kD protein contains five GL1-Kruppel type zinc fingers at the C-terminus. At its N-terminus, ZF5 has a 41 amino acid region which was found to be homologous to the N-termini of several other zinc finger proteins. This region defines a new motif within zinc finger proteins which we have named the Zinc finger N-terminal (ZiN) domain. ZF5 binds to two sites in the c-myc promoter and to the -50 bp site of the herpes simplex thymidine kinase promoter. ZF5 is a transcriptional repressor and its repression domain is located N-terminal to the zinc finger domains. A single 4 kb ZF5 mRNA is expressed widely.

Amino Acid Sequence↗