Search PubMed⌕ Search

Biomedical subjects

T Akiba

Publications and source records attributed to T Akiba.

At least 145 records · Page 8Linked to original sources
PubMed1989

Clinical significance of renal hemodynamics in severe congestive heart failure: responsiveness to ultrafiltration therapies.

Isolated ultrafiltration, hemodialysis & peritoneal dialysis (Tx) were recently used in the treatment of intractable heart failure (HF). We examined the relation between the response of HF to Tx and the residual kidney functions. Tx was carried out in 17 patients (Pts) with HF who did not respond to aggressive medical treatment. Ten Pts (R) responded to Tx and 7 Pts (N) did not. Serum urea nitrogen (UN), creatinine (Cr), uric acid (UA), sodium (Na), potassium (K), and chloride (Cl) concentrations on admission and before Tx were not different between R and N. Urine UN, Cr, Na, K, and Cl on admission and before Tx were also not significantly different. Fractional sodium excretions (FENa), renal failure indices (RFI), and urine/plasma Cr ratios (U/P Cr) on admission were 2.0 +/- 1.6, 2.7 +/- 2.2, and 30.5 +/- 20.0 in R and 5.9 +/- 4.2, 8.2 +/- 6.0 and 11.5 +/- 3.8 in N. They were significantly different (p less than 0.05). However, these did not differ before and after Tx. These data show that FENa, RFI and U/P Cr might be useful indices in predicting the responsiveness of intractable HF to Tx.

Adult↗
PubMed1988

Prediction of peak pulmonary artery pressure by continuous-wave Doppler echocardiography in infants and children.

Continuous-wave Doppler echocardiography was used to estimate peak pulmonary artery (PA) pressure in 104 infants and children, aged 4 days to 16 years, with normal hearts (control group) and 43, aged 29 days to 13 years, with various kinds of heart disease (patient group). The Doppler transducer was directed toward the right ventricular outflow tract and angled until the maximal velocity signal was reached. Doppler velocity time intervals were measured as follows: acceleration time (AT), from the onset to the peak of the velocity curve; and ejection time (ET), from the onset to the termination of the velocity curve. In the control group, AT corrected through dividing by the RR interval of the electrocardiogram (ATc), and AT/ET by dividing by the square root of the RR interval (AT/ETc), were independent of body surface area. In the patient group, peak PA pressure had a significant inverse correlation with both ATc (r = -0.78) and AT/ETc (r = -0.87). Thus, AT/ETc derived from continuous-wave Doppler echocardiography is a good quantitative predictor of peak PA pressure in infants and children.

Adolescent↗
PubMed1988

Temperature-induced change of thick filament and location of the functional sites of myosin.

The combination of the small-angle X-ray camera to use the synchrotron radiation (National Lab. of High Energy Physics, Tsukuba) and a sensitive X-ray detecting system (FCR System, Fuji Medical System Inc.) using the imaging plate enabled us to record a small angle X-ray diagram of liver rabbit muscle within few minutes. Live relaxed rabbit muscle kept at 25 degrees C gave clear relaxed pattern, in which myosin layer line can be observed up to 13th order. When it was cooled down to 5 degrees C, it gave the small-angle X-ray pattern which looks like that obtained from contracting frog muscle, whereas cooled muscle produced no tension. The 8th meridional reflection almost vanished. The pattern is different from that obtained from rigor muscle: actin layer line at 72 A spacing can not be observed. The "stiffness" and (1,1) reflection on the equator increased. This indicates that more crossbridges are at the vicinity of the thin filaments without developing tension at low temperature. This might be related to the marked decrease in the rate of the step from M*ADP to M.ADP at low temperature. The position of the ATP binding site, SH1, actin binding site(s) was determined by three-dimensional image reconstruction method. Actin-binding site was determined by comparing the three-dimensional image of actin-tropomyosin-S1 and that of actin-tropomyosin-troponin-Ca. The position of ATP binding site and SH1 was determined by three-dimensional reconstruction of the complexes of actin-tropomyosin and S1 of which the ATP binding site or SH1 was labelled with avidin. It was found that SH1 locates near the actin-binding site at the same side of S1. The distance from head-rod junction to ATP binding site and SH1 was similar. But they locate at the different side of S1 and the distance between two sites is about 5 nm, which is consistent with that obtained by energy transfer method.

Animals↗
PubMed1987

Heterogeneity in mechanisms of bradykinin action in canine isolated blood vessels.

The relaxation induced by bradykinin in helical strips of coronary arteries contracted with prostaglandin (PG) F2 alpha was abolished by removal of the endothelium and was markedly suppressed by treatment with methylene blue or AA861, a lipoxygenase inhibitor. Indomethacin did not alter the response. Renal arterial relaxation by bradykinin was partially reduced by removal of the endothelium. Indomethacin moderately attenuated the response in the strips with endothelium and additional treatment with methylene blue or AA861 suppressed the response further. Tranylcypromine or diphloretin phosphate, an antagonist of PGI2, attenuated the peptide-induced relaxation. In mesenteric veins, the relaxation induced by bradykinin was slightly reduced by removal of the endothelium; indomethacin reversed the relaxation to a contraction in the strips with or without endothelium. Des-Arg9-[Leu8]bradykinin, a bradykinin B1 antagonist, did not alter the relaxation due to bradykinin in coronary arteries but reduced the response of mesenteric veins. It appears that bradykinin-induced relaxation is associated exclusively with EDRF in dog coronary arteries, with both PGI2 and EDRF in the renal arteries, and only with PGI2 liberated from endothelial and subendothelial tissues in the mesenteric veins. The release of PGI2 and EDRF may be mediated by activation of B1 and B2 receptor subtypes, respectively.

Animals↗
PubMed1987

Relationship between the replication of hepatitis B virus and the localization of virus nucleocapsid antigen (HBcAg) in hepatocytes.

According to the localization of hepatitis B virus (HBV) core antigen (HBcAg), detected by the avidin-biotin complex method, infected hepatocytes were classified into three types, i.e. those having nuclear (type I), nuclear and cytoplasmic (type II) or only cytoplasmic (type III) antigen. HBcAg-positive hepatocytes of all specimens (three) from non-specific reactive hepatitis and of most (five of seven) from chronic persistent hepatitis (CPH) patients were only type I; the other two CPH samples and all (seven) chronic active hepatitis samples were composed of a mixture of types I, II and III. Linear correlations between the frequency of type I, as well as that of of all types (I, II and III) of the HBcAg-positive hepatocytes, and the amount of HBV DNA in serum were found. The relative HBV production of HBcAg-positive hepatocytes (serum HBV DNA amount/frequency of HBcAg-positive cells) was 0.11 in type I and 0.07 in all hepatocytes including types I, II and III. HBV core particles and complete HBV particles were found in type I hepatocytes. On the other hand, these particles were not found in a predominantly type III liver specimen. These results suggest that type I hepatocytes are more involved in the propagation of HBV than types II and III.

DNA Replication↗
PubMed1987

Parallel adaptation of the rabbit renal cortical sodium/proton antiporter and sodium/bicarbonate cotransporter in metabolic acidosis and alkalosis.

Recent studies have shown that the bicarbonate reabsorptive capacity of the proximal tubule is increased in metabolic acidosis. For net bicarbonate reabsorption to be regulated, there may be changes in the rate of apical H+ secretion as well as in the basolateral base exit step. The present studies examined the rate of Na+/H+ exchange (acridine orange method) and Na+/HCO3 cotransport (22Na uptake) in apical and basolateral membranes prepared from the rabbit renal cortex by sucrose density gradient centrifugation. NH4Cl loading was used to produce acidosis (arterial pH, 7.27 +/- 0.03), and Cl-deficient diet with furosemide was used to produce alkalosis (arterial pH, 7.51 +/- 0.02). Maximal transport rate (Vmax) of Na+/H+ antiporter and Na+/HCO3 cotransporter were inversely related with plasma bicarbonate concentration from 6 to 39 mM. Furthermore, the maximal transport rates of both systems varied in parallel; when Vmax for the Na+/HCO3 cotransporter was plotted against Vmax for the Na+/H+ antiporter for each of the 24 groups of rabbits, the regression coefficient (r) was 0.648 (P less than 0.001). There was no effect of acidosis or alkalosis on affinity for Na+ of either transporter. We conclude that both apical and basolateral H+/HCO3 transporters adapt during acid-base disturbances, and that the maximal transport rates of both systems vary in parallel during such acid-base perturbations.

Acidosis↗
PubMed1987

A case report of adenocarcinoma of the lung in which a partial response was achieved by carboplatin.

A 56-year-old housewife was incidentally discovered to have an abnormal shadow in the right B6 area upon a chest X-ray film being taken. A transcutaneous lung biopsy of the mass revealed adenocarcinoma of the lung (WHO classification). A brain computed tomography (CT) scan demonstrated multiple brain metastasis. Following whole brain irradiation, carboplatin (CBDCA) (450 mg/m2) was administered by intravenous drip infusion on March 7, 1986. After three weeks of initial treatment with CBDCA, the size of the tumor in the primary site was found to have decreased on the chest X-ray film by more than 50%, following which, similar doses of CBDCA were administered twice, and reduced (330 mg/m2) doses three times every three to four weeks. She showed a partial response and, for seven months after the beginning of the CBDCA treatment, no progression was seen on the chest X-ray film. It is suggested that there is a need for further phase II studies of CBDCA against non-small cell lung cancer.

Adenocarcinoma↗
PubMed1987

A case of adenocarcinoma of the lung which was successfully treated by chemotherapy with patient survival without recurrence for more than three years.

A 63-year-old man was admitted to the National Cancer Center Hospital on December 20, 1983 for a close examination of the abnormal shadows found in chest roentgenograms. Chest radiographs showed a massive right pleural effusion, a large tumor in the right hilar region and swelling of the left hilar nodes. Transcutaneous needle biopsy revealed the tumor's cytological type to be adenocarcinoma. The clinical stage was considered to be T3N2M1 (American joint committee (AJC) stage III M1), and his performance status was 4, so he was given etoposide (VP-16) alone as the initial chemotherapy treatment. He showed a partial response upon two courses of VP-16 therapy. Subsequently, one course of cisplatin (80 mg/m2) + vindesine (3.3 mg/m2), two courses of VP-16 (80 mg/m2 D1-4), five courses of cyclophosphamide (80 mg/m2) + adriamycin (50 mg/m2) + vincristine (1.4 mg/m2) and two courses of VP-16 (100 mg/m2 D1, 3, 5) were administered sequentially until May 31, 1985. No radiation therapy was given and, up to March 31, 1987, no sign of recurrence had been observed.

Adenocarcinoma↗
PubMed1986

Conversion of muscle fiber types in regenerating chicken muscles following cross-reinnervation.

Slow-tonic anterior latissimus dorsi (ALD) and fast-twitch posterior latissimus dorsi (PLD) muscles of 7 to 10-day-old White Leghorn chickens were crushed and allowed to be reinnervated by their own nerve, or crushed and transplanted to the other side and allowed to be reinnervated by the nerve of the side to which they were transplanted. Following transplantation, changes in the weight of the muscle, fiber-type composition and innervation pattern during regeneration were investigated. Normal growth rate of PLD was about twice that of ALD. Regenerating PLD, however, atrophied rapidly after crushing and denervation whether innervated by its own nerve or the other nerve type, whereas ALD reinnervated by its own nerve showed marked hypertrophy. PLD fibers transformed rapidly to fast-twitch alpha or slow-tonic (ST) fibers when they were reinnervated by PLD or ALD nerve, respectively. When ALD fibers were reinnervated by their own nerve, they differentiated into ST fibers that were surrounded by smaller immature fibers. ALD fibers were, however, resistant to complete control by fast-twitch PLD nerve and contained a large number of slow fibers (ST and beta) long after transplantation. Slow fibers in regenerates were initially multiply innervated, but later transformed into fast-twitch alpha fibers that were focally innervated. The mode of differentiation and innervation pattern of different muscle fiber types in regenerating muscles are discussed.

Acetylcholinesterase↗
PubMed1986

Vasodilator actions of TRK-100, a new prostaglandin I2 analogue.

TRK-100, a stable analogue of prostaglandin I2 (PGI2), relaxed isolated arteries of the dog precontracted with PGF2 alpha or K+; the relaxation was in the order of mesenteric and renal greater than coronary and femoral greater than basilar and middle cerebral arteries. The relaxation by TRK-100 was not affected by treatment with atropine, propranolol, cimetidine, aminophylline, and indomethacin, but was suppressed by diphloretin phosphate, a prostaglandin antagonist. Treatment with TRK-100 attenuated the contraction induced by PGF2 alpha and Ca2+ in mesenteric and basilar arteries previously exposed to Ca2+-free medium, but did not significantly alter the contractile response to Ca2+ in the arteries exposed to Ca2+-free medium and depolarized by excess K+. TRK-100 and nitroglycerin relaxed isolated mesenteric arteries to a similar extent; however, when continuously infused into mesenteric arteries in anaesthetized dogs, TRK-100 produced greater vasodilatation than nitroglycerin. It is concluded that TRK-100 relaxes dog mesenteric and renal arteries more than cerebral arteries; the relaxation appears to derive from interference with the release of Ca2+ from intracellular stores and with the transmembrane Ca2+ influx through a receptor-operated channel. TRK-100 may vasodilate large and small mesenteric arteries and resistance vessels to a similar extent, whereas nitroglycerin preferentially dilates the large artery.

Animals↗
PubMed1986

Electrogenic sodium/bicarbonate cotransport in rabbit renal cortical basolateral membrane vesicles.

The present studies examined the mechanism of bicarbonate transport across basolateral membrane vesicles prepared from rabbit renal cortex. Isotopic sodium uptake was stimulated by bicarbonate when compared with gluconate (2.5 nmol/mg protein per 5 s versus 1.4 nmol/mg protein per 5 s), and this process was inhibited by disulfonic stilbenes. Imposition of an interior-positive potassium diffusion potential further stimulated isotopic sodium uptake to 3.4 nmol/mg protein per 5 s, an effect that occurred only in the presence of bicarbonate and was blocked by disulfonic stilbenes. Kinetic analysis of the rate of bicarbonate-dependent sodium uptake as a function of sodium concentration revealed saturable stimulation with a Vmax of 2.7 nmol/mg protein per 2 s and a Km of 10.4 mM. The effect of bicarbonate concentration on bicarbonate-dependent sodium uptake was more complex. The present results demonstrate an electrogenic (negatively charged) sodium/bicarbonate cotransporter in basolateral membrane vesicles from the rabbit renal cortex. The electrogenicity implies a stoichiometry of at least two bicarbonate ions for each sodium ion.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1986

Assessment of cardiac performance by first pass radionuclide angiocardiography in infants and children with normal heart and endocardial fibroelastosis.

Peak to peak time from the right and to the left ventricle (PPT), left ventricular ejection fraction, left ventricular peak ejection rate and left ventricular peak filling rate were measured by first pass radionuclide angiocardiography in 27 infants and children with normal heart and in 8 patients (18 studies) with endocardial fibroelastosis. In normal subjects, the PPT significantly correlated with heart rate (r = -0.87, p less than 0.001). A PPT corrected by the heart rate (cPPT) was calculated by rotation of the regression equation relating the variables: cPPT = PPT + 0.018 X (heart rate)-2.1. The cPPT averaged 3.0 +/- 0.0 (mean +/- S.E.) sec. Consequently, there was no significant correlation between the cPPT and heart rate, but the cPPT and body surface area are significantly correlated (r = 0.41, p less than 0.05). Left ventricular ejection fraction, peak ejection rate and peak filling rate averaged 68 +/- 2%, 4.2 +/- 0.3/sec and 4.8 +/- 0.3/sec, all of which were independent of the heart rate and body surface area. In patients with endocardial fibroelastosis, the cPPT was prolonged (4.7 +/- 0.4 sec), and left ventricular ejection fraction, peak ejection rate and peak filling rate were all reduced (28 +/- 4%, 1.7 +/- 0.2/sec and 1.8 +/- 0.2/sec). These results indicate that parameters obtained from the radionuclide angiocardiography are useful for evaluating cardiac performance in patients with endocardial fibroelastosis.

Child↗
PubMed1986

Echocardiographic measurements of left ventricle in normal infants and children.

Echocardiographic studies were performed on 110 normal infants and children ranging in age from 2 days to 15 years. The following parameters of the left ventricle were measured: left ventricular end-diastolic and end-systolic diameters (LVEDd and LVESd), shortening fraction (LVSF), end-diastolic volume (LVEDV), ejection fraction (LVEF), posterior wall thickness in end-diastole (LVPWED) and end-systole (LVPWES), mass (LVM), LVEDd/LVPWED, LVESd/LVPWES and mean velocity of circumferential fiber shortening (LV mean Vcf). Each parameter was compared with body surface area (BSA). LVEDd, LVESd, LVEDV, LVPWED, LVPWES and LVM were expressed as a function of body surface area with exponential equations: LVEDd = 41.4 (BSA)0.49 mm, LVESd = 28.1 (BSA)0.49 mm, LVEDV = 74.1 (BSA)1.48 ml, LVPWED = 4.4 (BSA)0.45 mm, LVPWES = 9.2 (BSA)0.44 mm and LVM = 46.4 (BSA)1.48 g. LVSF, LVEDd/LVPWED, LVESd/LVPWES and LV mean Vcf were independent of body surface area: LVSF averaged 32 +/- 1 (mean +/- standard error of the mean)%, LVEF 68 +/- 1%, LVEDd/LVPWED 10.0 +/- 0.2, LVESd/LVPWES 3.1 +/- 0.1 and LV mean Vcf 1.08 +/- 0.02 circ/sec. Thus, normal values of these parameters can be applied to estimate them in pediatric patients with heart diseases.

Adolescent↗
PubMed1986

Angiocardiographic estimation of left ventricular mass in normal infants and children.

Left ventricular mass data were obtained from biplane cineangiocardiograms in 37 normal infants and children. Left ventricular mass calculated by using thickness of anterior wall (left ventricular mass-anterior) and posterior wall (left ventricular mass-posterior) of the free left ventricular wall were studied in relation to body surface area and left ventricular end-diastolic volume. Both of left ventricular mass-anterior and mass-posterior were expressed as a function of body surface area with exponential relationship; left ventricular mass-anterior = 68.5 (body surface area) g (r = 0.98, p less than 0.01), left ventricular mass-posterior = 84.6 (body surface area) g (r = 0.97, p less than 0.01). Left ventricular mass-anterior/left ventricular end-diastolic volume averaged 0.73 +/- 0.01 g/ml, and left ventricular mass-posterior/left ventricular end-diastolic volume 0.89 +/- 0.02 g/ml, respectively. Thus, left ventricular mass can be predicted from body surface area by using the exponential equations. In addition, normal values for left ventricular mass-posterior must be discriminated from those for left ventricular mass-anterior.

Angiocardiography↗