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Biomedical subjects

T Nakamoto

Publications and source records attributed to T Nakamoto.

At least 109 records · Page 6Linked to original sources

Interaction between zinc and calcium in skeletal muscle in young growing rats.

The purpose of the present study was to determine whether zinc and calcium could interact at the tissue level. In the first part of the study, adult rats were injected with ZnCl2 dissolved in a physiological saline solution to determine the effects of Zn on Ca levels in various tissues. In the second part of the study, weaned rats (at day 22 postnatally) were fed a diet supplemented with Zn until day 50 and were then sacrificed. In both instances, blood, brain, heart, liver, and skeletal muscle were taken and analyzed. In the Zn-injected group, the brain, heart, and liver showed no interaction between Zn and Ca. The skeletal muscle, in contrast, showed a decrease in Ca in the homogenate, whereas Zn contents showed a significant increase at the sarcoplasmic reticulum (SR). Likewise, in the Zn-supplemented group, the Zn content of the SR vesicle of the skeletal muscle showed an increase, whereas Ca content of the pellet (14,000 g), which contains cell debris, nucleus, mitochondria, and SR vesicles of this group, showed a decrease. Current findings suggest antagonistic effects between Zn and Ca on this tissue. Zn may play a critical role in cellular function through the alteration of intracellular distribution of Ca in skeletal muscle.

Animal Nutritional Physiological Phenomena↗

Cariogenic effect of caffeine intake during lactation on first molars of newborn rats.

Lactating dams with eight suckling pups were fed either a 20% protein diet as a control or experimentally a 20% protein diet supplemented with caffeine (2 mg/100g body weight) from the birth of the pups to day 22. At day 22, the pups from both groups were weaned and fed a cariogenic diet until day 50, when they were killed. Dental caries of the molars were scored from randomized mandibles. The enamel of the first molars in the caffeine group showed significantly higher caries scores than that of the controls. This appears to be the first unequivocal evidence that caffeine is a cariogenic agent when newborns are exposed to it during critical periods of tooth development. Therefore, the widespread human consumption of caffeine could be a threat to the healthy development of teeth.

Animals↗

The effect of prenatal caffeine exposure on the enamel surface of the first molars of newborn rats.

Timed-pregnant rats were randomly divided into three groups at day 7 of gestation. A caffeine tablet was implanted subcutaneously in the experimental group and a placebo tablet in the control group. The third group was used as surrogate dams. At birth, eight randomly selected pups born either to the experimental or control dams were placed with surrogate dams that had produced pups on the same day; these were then used in either the experimental or the control group, and so the surrogate dams raised pups that came from either the experimental or control group. At day 22 after birth, the pups were killed, and their first and second maxillary and mandibular molars were removed. They were then placed in a specially designed chamber and exposed to an acid solution. The outflowing acid solution was collected every 20 min and up to 80 min. Then the calcium, phosphorus, and magnesium contents of each fraction were measured. The enamel surfaces of untreated and acid-treated first molars of the caffeine and control groups were examined by scanning electron microscopy. Untreated teeth were powdered and separated into enamel and dentine. Pure enamel samples were examined with a Gandolfi X-ray powder camera to measure the crystallite size. At 20-, 40- and 60-min intervals, calcium and phosphorus contents of the first molars of the caffeine group were significantly higher than those of the control. The enamel surface of the untreated and acid-treated first molars of the caffeine group had significantly different scanning microscopic appearances from those of the non-caffeine untreated and acid-treated control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Long-term results of endourologic treatment of urinary calculi: investigation of risk factors for recurrence or regrowth.

To evaluate the risk factors related to the long-term outcome of endourologic treatment of urinary calculi, we examined rates of recurrence and regrowth in 167 renal units. The following risk factors were examined: age; previous stone; location, number, size, and composition of stone; and procedures. In our study sample, the overall recurrence and regrowth rates were 17% and 10%, respectively. The earliest recurrence and regrowth appeared at 3 months after treatment, and 71% occurred within 2 years. In 22% of renal units that were estimated to be stone-free, stones appeared later, and 45% of inadequately fragmented stones enlarged. Stones located in a renal calix and pelvis, multiple stones, large stones (more than 20 mm), stones composed of calcium oxalate or calcium phosphate or both, and struvite stones were likely to be risk factors, but there were no significant differences statistically. Although the possibility of several risk factors was suggested in our study, thorough fragmentation of stones and complete removal of fragments, combined with extracorporeal shock wave lithotripsy or chemolysis if needed, is ultimately responsible for successful treatment of urinary calculi.

Adolescent↗

Estimation of left ventricular elastance without altering preload or afterload in the conscious dog.

OBJECTIVE: The aim was to determine the slope (EES) of the left ventricular end systolic pressure-volume line (ESPVL) without altering preload or afterload in conscious dogs. METHODS: Dogs (n = 10) were instrumented to determine left ventricular volume from ultrasonic left ventricular internal dimensions, and to measure left ventricular pressure using a micromanometer. Studies were performed one to two weeks after instrumentation while the animals were conscious. ESPVL was determined from variably loaded left ventricular pressure-volume (P-V) loops generated by the vena caval occlusion. Contractile state was increased by intravenous dobutamine (8 micrograms.kg-1 x min-1) and decreased by intravenous verapamil (10 mg) given after autonomic blockade. From a single normally ejecting beat, we calculated EES-single beat (mm Hg.ml-1) as peak isovolumetric pressure (Pmax) minus end systolic pressure divided by stroke volume. Sunagawa's technique was used to estimate Pmax by fitting the pressure during the isovolumetric contraction and relaxation as: P(t) = 1/2 X Piso[1-cos(omega t+c)]+LVEDP, where Piso = peak isovolumetric developed pressure, LVEDP = left ventricular end diastolic pressure, c = constant accounting for variations in phase angle, and omega = 2 pi/T in which T is duration of contraction. RESULTS: After dobutamine, EES increased, from 8.9(SEM 0.8) to 12.5(1.0) mm Hg.ml-1 (p < 0.05), and EES-single beat increased from 9.1(0.9) to 12.0(1.4) mm Hg.ml-1 (p < 0.05). Conversely, after verapamil, EES decreased, from 11.1(1.2) to 6.3(1.1) mm Hg.ml-1, (p < 0.05), and EES-single beat also decreased, from 9.6(1.0) to 7.3(1.2) mm Hg.ml-1, (p < 0.05). CONCLUSIONS: EES calculated from one beat is similar to EES determined from variably loaded left ventricular loops and responds appropriately to inotropic stimulation. This technique provides a reasonable method to calculate EES from left ventricular pressure and stroke volume without altering preload or afterload.

Animals↗

Ventricular coupling via the pericardium: normal versus tamponade.

OBJECTIVE: The aim was to examine how regional variations in pericardial pressure affect the mechanical coupling between the ventricles. METHODS: Canine hearts from 14 dogs (14.5-18 kg) were removed and placed in cold cardioplegia solution. Balloons were inserted into the left and right ventricles and the atria. Pericardial pressure over the left ventricle (Pclv) and the right ventricle (Pcrv) was measured with thin balloon catheters. Ventricular and pericardial pressures were measured, and ventricular and pericardial coupling was calculated, under control conditions and with increases in pericardial tension and fluid. RESULTS: At baseline, regional differences in pericardial pressure occurred [Pclv > Pcrv, 4.0(SD 0.9) v 2.9(0.6) mm Hg, p < 0.05]. Ventricular coupling via the pericardium was defined as delta Pclv/delta Pcrv for right ventricular volume increases and delta Pcrv/delta Pclv for left ventricular volume increases. This ratio increased more after increasing right ventricular volume than after increasing left ventricular volume [delta Pclv/delta Pcrv > delta Pcrv/delta Pclv, 1.14(0.33) v 0.51(0.15), p < 0.05]. Increasing the pericardial tension by clamping the pericardium increased pericardial pressures, yet did not alter the regional variations in pressure [Pclv > Pcrv, 8.4(2.2) v 6.4(2.5) mm Hg, p < 0.05] or pericardial coupling [delta Pclv/delta Pcrv > delta Pclv/delta Pcrv, 1.18(0.46) v 0.54(0.16), p < 0.05]. In contrast, creating a mild tamponade increased pericardial pressures, eliminated regional differences in pressure, and altered the coupling between ventricles [delta Pclv/delta Pcrv approximately delta Pclv/delta Pcrv, 0.95(0.11) v 1.05(0.08), p = NS]. These regional differences in pericardial pressure might have a geometrical basis. In four in vivo canine experiments using cine magnetic resonance, the short axis radius of curvature for the right ventricle was greater than for the left ventricle [38.3(4.4) mm v 29.2(3.8) mm, p < 0.05]. CONCLUSIONS: The pericardium partially protects right ventricular filling: regional differences in pericardial pressure normally occurred with lower pericardial pressure over the right ventricle, and left to right ventricular coupling was less. This protection of right ventricular filling was lost with even a small pericardial effusion.

Animals↗

[Albumin and fibronectin dynamics in an experimental adult respiratory distress syndrome model].

We produced an experimental adult respiratory distress syndrome model by intravenous administration of oleic acid (OA) in 30 dogs (Group I: 10 normal dogs; Group II: 10 dogs with 0.02 ml/kg of OA; Group III: 10 dogs with 0.04 ml/kg of OA; Group IV: 10 dogs with 0.08 ml/kg of OA). Changes in albumin (AL) and fibronectin (FN) in serum and BALF of these dogs were examined. The following results were obtained: 1) Serum values of AL and FN were significantly decreased after OA injection as compared with the baseline values. These changes were not correlated with the severity of pulmonary edema. 2) BALF values of AL and FN were significantly increased after OA injection as compared with the baseline values. Significant linear correlations were found between the BALF value of AL and ELWV, and between BALF value of AL and delta ELWV, [r = -0.682, 0.573 (p < 0.01)]. Significant linear correlations were also found between the BALF value of FN and ELWV, and the BALF value of FN and delta ELWV, [r = 0.722, 0.650 (p < 0.01)]. BALF value of AL increased significantly even with the low OA dose (0.02 ml/kg). Thus in comparison with BALF value of AL after OA injection, BALF value of FN was significantly higher than that in the normal group even when pulmonary edema were severe (Groups III and IV). We concluded that we could estimate the severity of pulmonary edema by measuring BALF value of AL and FN simultaneously.

Animals↗

Basic fibroblast growth factor in human prostate cancer cells.

To increase our understanding of the potential role of basic fibroblast growth factor (bFGF) in malignant progression of prostate cancer, we determined the production of bFGF, the expression of FGF receptor (flg), and the response to exogenous bFGF in LNCaP, DU 145, and PC 3 cells. We observed that these three prostate cancer cell lines, which differed in their dependence on androgens for growth in vitro and in their in vivo behavior in nude mice, could be distinguished as follows: (a) androgen-sensitive LNCaP cells, which do not metastasize in nude mice, did not produce measurable amounts of bFGF, expressed small but measurable amounts of FGF receptor mRNA, and did respond to exogeneous bFGF; (b) androgen-insensitive, moderately metastatic DU 145 cells did produce measurable amounts of biologically active bFGF, expressed large amounts of FGF receptor mRNA, and responded to exogeneous bFGF and the heparin-binding fractions from DU 145 cell extracts; (c) androgen-insensitive and highly metastatic PC3 cells also produced measurable amounts of bFGF but did not demonstrate a growth response to either the heparin-binding fractions from PC3 cell extracts or exogenous bFGF, even though large amounts of FGF receptor mRNA were expressed in PC 3 cells. These results suggest the possibility that differences in production of, and response to, bFGF may be associated with different biological behavior.

3T3 Cells↗

The effects of caffeine on the maxillary composition in the newborn rat.

The possible influence of caffeine on maxillary structure was studied. Seventeen pregnant rats at days 9 of gestation were randomly divided into two groups. The dams of group 1 received a 20% protein diet ad libitum throughout the experimental period. The dams of group 2 were pair-fed, with group 1, a 20% protein diet supplemented with 2 mg/100 g body weight (B.W.) caffeine. At birth, pups were mixed within the same group and 8 randomly selected pups were assigned to each dam and continuously fed the respective diet. On day 22, 11 male pups from the control and 12 males from the caffeine group were randomly selected, separated from the dams, and continued to be fed their respective diets. On day 44, a rubber elastic band was inserted between the first and second maxillary right molars. The size of the elastic band was increased throughout the next 5 days. Animals were sacrificed at day 49 and the composition of the maxillas was analyzed. After pulverization, organic and inorganic contents of the bones were measured. Zinc (Zn) and hydroxyproline concentration of the caffeine group showed a significant decrease when compared with those of the controls. However, Ca, P, Mg, and hexosamine concentration showed no difference between the groups. The interdental space measured occlusally and laterally with the visual method, and occlusally in histological sections showed no significant difference between the control and caffeine groups, although variation of the space in the caffeine group was less than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Effect of caffeine and zinc on DNA and protein synthesis of neonatal rat cardiac muscle cell in culture.

The effect of caffeine and/or zinc on DNA and protein synthesis of purified neonatal-rat ventricular cardiac myocytes was studied. Caffeine (0.2-2 mM) inhibited both DNA and protein synthesis of the cells. Addition of EDTA in the growth medium inhibited both DNA and protein synthesis. Without caffeine and in the presence of lower concentrations of caffeine (0.2 mM) in the growth medium, 10 microM of zinc concentration reversed DNA synthesis, which was inhibited by the chelating agent (EDTA). Higher concentrations of caffeine (2 mM) in the growth medium completely abolished sensitivity of cardiac myocytes to zinc. Additional zinc supplementation to the growth medium of cardiac myocytes did not alter the rate of protein synthesis. The present results suggest that the effect of caffeine on cardiac myocytes may be associated with the zinc-dependent enzymes involved in DNA synthesis.

Animals↗

Effects of maternal caffeine intake during lactation on molar enamel surfaces in new-born rats.

Dams were fed normal laboratory chow until delivery. At birth, the litters were combined, and eight pups were randomly assigned to each dam. Dams with the recombined litters were divided into two groups. Dams of group 1 were fed a 20% protein diet as a control; dams of group 2 were fed a 20% protein diet supplemented with caffeine (2 mg/100 g of the dam's weight). On day 22, the dams of group 2 were anaesthetized with ether. They were injected with 2 iu of oxytocin in order to collect milk. Blood was collected from pups and dams to determine its caffeine concentration. The first and second molars were removed from each pup's mandible and maxilla. Radiographs were taken of 10 randomly selected first or second molars from each group. Four randomly selected molars from each litter were placed in a specially designed chamber and bathed with a constant flow of acid solution to determine the amount of mineral dissolved from the enamel surfaces. The remaining non-acid exposed molars were pulverized in freezer mills. A small portion of this powder was then analysed for the total amount of minerals. No differences were found in the radiographic density of enamel between the groups. The amount of dissolved calcium, phosphorus and magnesium from enamel surfaces in the caffeine group was consistently greater than that of the non-caffeine group in the first molars, whereas, in the second molars, there was no difference between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Physical examination of caffeine's effects on the enamel surface of first molar in new-born rats.

Samples of the first molars of offspring whose dams were fed a diet supplemented with caffeine were examined by scanning electron microscopy, X-ray diffractometry and electron microprobe analysis. Scanning microscopy of the enamel surface of the caffeine group revealed a consistently rougher surface than in the non-caffeine controls, both before and after acid exposure. X-ray diffraction analysis of the pulverized whole tooth in the caffeine group showed broader diffraction peaks for the lattice plane reflections (202) and (300), indicating smaller crystallites. Pure enamel samples of the caffeine group examined with a Gandolfi X-ray camera also revealed more diffuse diffraction lines than in the non-caffeine controls, further indicating smaller crystallites in the enamel. The calcium and phosphorus contents of the acid-exposed samples in both control and caffeine groups were lower than the non-acid exposed control and caffeine groups by electron microprobe analysis. After exposure to acid, the calcium and phosphorus contents of the outer surface of the enamel in the caffeine group were greatly reduced as compared to that of the non-caffeine controls. Thus various methods consistently indicate that caffeine ingestion during early growth affects the enamel surface of the first molars, resulting in impaired mineralization. Caffeine intake may therefore have a negative effect on amelogenesis and possibly increases susceptibility to dental caries.

Animals↗

Effects of caffeine on the DNA and protein synthesis of the protein-energy malnourished neonatal cardiac muscle cells in culture.

1. The growth of cardiac cells derived from newborn rats whose dams were either malnourished or malnourished with caffeine during pregnancy was inhibited in culture over the period of 5 days as compared to that of the normally nourished cells. 2. Cells derived from malnourished rats with caffeine added to their diets showed a greater inhibition than those from the malnourished rats not given caffeine. 3. Both DNA and protein synthesis showed an inhibition due to caffeine in a dose-dependent manner using normally nourished cells. 4. In the presence of exogenous 2 mM caffeine, the degree of percent inhibition of DNA and protein synthesis of cells derived from rats malnourished with caffeine was less than that from the rats with malnutrition alone. 5. The present data indicated that malnutrition combined with caffeine during pregnancy exerted a greater negative effect on the nature of cell growth than malnutrition alone and these cells became less sensitive to exogenous caffeine.

Animals↗

Differential effects of positive end expiratory pressure and cardiac tamponade on left-right ventricular mechanical function in the dog.

OBJECTIVE: The aim was to examine the hypothesis that an increased coupling occurs between the ventricles during tamponade via a ventricular-pericardial-ventricular interaction, but that ventricular coupling would be unaltered or reduced with positive end expiratory pressure (PEEP). METHODS: An in situ arrested, canine heart preparation was used. Changes in left and right ventricular pressure (dPl, dPr) and volume (dVl, dVr) caused by increasing the volume of the other ventricle were measured at normal and at matched levels of raised pericardial pressures (Pp) caused by 20 cm H2O PEEP and by tamponade. RESULTS: With PEEP, the coupling between the ventricles was unaltered when compared to control. With tamponade, dPl/dPr, dVl/dPr, dPr/dPl, and dVr/dPl increased significantly (p less than 0.05) by 0.21 (SEM 0.03, unitless), 0.45(0.04) ml.mm Hg-1, 0.18(0.03), and 0.28(0.04) ml.mm Hg-1 respectively. CONCLUSIONS: Augmented ventricular interdependence occurs during tamponade but not with PEEP, which may help to explain the different haemodynamic patterns observed under these conditions.

Animals↗

Caffeine decreases zinc and metallothionein levels in heart of newborn and adult rats.

The purpose of the present study is to show that dietary caffeine, heart tissue Zn levels, and metallothionein (MT) concentration are all interrelated in newborn rats. Dams with eight pups in the control group were fed a 20% protein diet upon delivery, whereas dams in the experimental group were fed a 20% protein diet supplemented with caffeine (2 mg/100 g body weight). Offspring were killed at d 22 postbirth and the hearts and livers were removed to determine the Zn and MT concentrations. Hearts of the newborn rats in the caffeine group showed decreased Zn levels as well as decreased MT concentration. To explain the observed effects in newborn rats, the relationship between Zn and MT levels was studied in adult female rats. They were injected intraperitoneally with either ZnCl2 (20 mg/kg body weight) dissolved in saline solution or ZnCl2 and caffeine (4 mg/kg body weight) over a period of 2 d. Injection of ZnCl2 into adult female rats resulted in an increase in heart MT levels, whereas injection of caffeine caused decreased Zn levels and MT concentration. Current findings indicate that dietary caffeine intake during the lactational period by newborn pups causes a decrease of the heart Zn and MT levels.

Animals↗

Sandwich immunoassay for intact human osteocalcin.

To overcome the problems of limited-region specificity associated with conventional radioimmunoassay (RIA), we developed a sandwich enzyme immunoassay (EIA) for intact human osteocalcin (hOC). For this EIA we used antibodies to the N- and C-terminal regions of hOC that were raised against an N-terminal 20-residue peptide and a C-terminal 7-residue peptide, both synthetic. Immunoassay profiles of tryptic digests of hOC and serum from patients with renal failure, fractionated by reversed-phase HPLC, facilitated direct demonstration of the region specificity of this method. A preliminary study of serum osteocalcin concentrations in patients with renal failure further confirmed this specificity, showing lower positive rates obtained by this method than by conventional RIA. The cross-reactivity data of hOC with bovine and rat osteocalcins by the sandwich method indicated its species specificity. These studies demonstrate the superior specificity of this sandwich EIA compared with conventional RIA and thus confirm its potential diagnostic superiority.

Adult↗

[Estimation of pulmonary vascular permeability by indocyanine green in permeability pulmonary edema].

In this study we attempted to estimate pulmonary vascular permeability by indocyanine green (ICG). Permeability pulmonary edema was produced in 9 adult dogs by injecting 0.08 ml/kg oleic acid. We injected 50 mg ICG intravenously in 18 dogs (9 dogs with pulmonary edema and 9 control dogs). We measured the time course of ICG concentrations in pulmonary arterial blood, ICG concentration of peripheral lung tissue, tissue/serum ICG concentration ratios, and wet/dry lung weight ratios. The following results were obtained. The time course of ICG concentration in pulmonary arterial blood showed peak values at 2 minutes and became constant at 5 or 10 minutes after injection. The ICG concentration in peripheral lung tissue, tissue/serum ICG concentration ratios, and wet/dry lung weight ratios in the pulmonary edema group were significantly higher than those in the normal group. There was a strong linear correlation between wet/dry lung weight ratio and ICG concentration in peripheral lung tissue, with correlation coefficients of r = 0.936 (p < 0.01) in the right lung and r = 0.901 (p < 0.01) in the left lung. From these results, we conclude that estimation of pulmonary vascular permeability by ICG is a useful method.

Animals↗