Biomedical subjects

K Nitta

Publications and source records attributed to K Nitta.

At least 199 records · Page 11Linked to original sources

PubMed1993

Characterization of the glomerular endothelial cell in culture.

Because of difficulties associated with the culture, cloning and propagation of glomerular endothelial cells (GENs), the biological properties of these cells remain largely unknown. We modified the methods established by Ballermann to propagate GENs from adult bovine kidney. We found that the addition of insulin, transferrin and selenium into the standard culture media was an important step in promoting the propagation of the first clone from a single cell and in maintaining the viability of the cells. These cells expressed factor VIII-related antigen and took up acetylated-LDL, but did not contain the Weibel-Palade body, unlike endothelial cells derived from large vessels. Furthermore, GENs were compared with aortic endothelial cells (AECs) to investigate the differences in culture conditions. Compared with AECs, GENs required a higher concentration of serum and the supplementation of growth factor to maintain their biological activity. In addition, GENs were very susceptible to trypsinization and produced prostaglandin E2 as a major cyclooxygenase product, whereas AECs produced PGI2. These findings suggest that GENs will be easily obtained from adult bovine kidney in culture and provide useful information on the functional properties of these cells under physiological and pathophysiological conditions.

Animals↗

PubMed1993

[Role of glomerular mesangial cells in the regulation of glomerular endothelial cell growth].

Because of difficulties of propagating and cultivating glomerular endothelial cells (GEN), the role of glomerular mesangial cells (GMC) in the regulation of GEN growth is still unknown. We cloned individually GEN and GMC from the same adult bovine kidneys, and a direct coculture system was established to examine the interactions between GEN and GMC. When cocultured with GMC which was growth arrested by mitomycin C, the GEN growth was inhibited by 63% after 8 days of the beginning of coculture. No inhibitory activity was detected when media conditioned by individual culture of GMC. In contrast, media conditioned by GEN cocultured with GMC inhibited bromodeoxyuridine (BrdU) uptake of GEN detected by flow cytometry. Addition of anti-transforming growth factor (TGF)-beta antibody to media conditioned by coculture blocked the inhibitory actions of conditioned media on GEN growth. Western blotting analysis of conditioned media by coculture revealed an existence of TGF-beta in the media. These results indicate that latent TGF-beta is produced by these cells and activated in coculture of GEN and GMC.

Animals↗

PubMed1992

Thermodynamic changes in the binding of Ca2+ to a mutant human lysozyme (D86/92). Enthalpy-entropy compensation observed upon Ca2+ binding to proteins.

The thermodynamic change in the binding of Ca2+ to a mutant human lysozyme having an engineered Ca2+ binding site (Kuroki, R., Taniyama, Y., Seko, C., Nakamura, H., Kikuchi, M., and Ikehara, M. (1989) Proc. Natl. Acad. Sci. U. S. A. 86, 6903-6907) was analyzed by calorimetry and interpreted in terms of structural information obtained from x-ray crystallography. It was found that the enthalpic contribution for the Ca2+ binding reaction was small, driven primarily by entropy release (10 kcal/mol). This release of entropy was also observed in some organic chelators. Moreover, through the information of the tertiary structures of the apo- and holomutant lysozyme, it was confirmed that the entropy release (10 kcal/mol) upon the binding of Ca2+ arises primarily from the release of bound water molecules hydrating the free Ca2+. Previous studies of Ca2+ binding to proteins have involved significant changes in protein conformation. They can now be reevaluated to determine the contribution of conformational changes to Ca2+ binding. After removing the thermodynamic contribution of Ca2+ binding itself, it is found that upon the binding of Ca2+ the enthalpy change is negative but is almost compensated by the negative entropy change. The negative change in both enthalpy and entropy is characteristic of values seen in the thermodynamic change upon the folding of proteins.

Amino Acid Sequence↗

PubMed1992

Calcium-43 NMR studies of calcium-binding lysozymes and alpha-lactalbumins.

The calcium-binding properties of equine and pigeon lysozyme as well as those of bovine and human alpha-lactalbumin were investigated by 43Ca NMR spectroscopy. All proteins were found to contain one high-affinity calcium-binding site. The chemical shifts, line widths, relaxation times (T1 and T2), and quadrupole coupling constants for the respective 43Ca NMR signals were quite similar; this is indicative of a high degree of homology between the strong calcium-binding sites of these four proteins. The measured chemical shifts (delta approximately -3 to -7 ppm) and quadrupole coupling constants (chi approximately 0.7-0.8 MHz) are quite distinct from those observed for typical EF-hand calcium-binding proteins, suggesting a different geometry for the calcium-binding loops. The correlation times for bound calcium ions in these proteins were on the order of 4-8 ns, indicating that the flexibilities of these binding sites are limited. The apparent pKa values for the high-affinity sites ranged from 3.4 to 4.7, confirming the participation of carboxylate-containing residues in the coordination of the calcium ion. Competition experiments with EDTA showed that the affinities of these proteins for calcium follow the series bovine alpha-lactalbumin approximately human alpha-lactalbumin greater than pigeon lysozyme greater than equine lysozyme (KD approximately 5 x 10(-8) to 10(-6) M). Evidence for the existence of a second weak calcium-binding site (KD = 3 x 10(-3) M) was obtained for bovine alpha-lactalbumin, but not for the other proteins studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Material flow estimation in CELSS.

Through the tentative lunar base construction study aiming to explore the system design method regarding closed loop life support system, the feasible system configuration including many subsystems is defined. Based upon this configuration and the estimated metabolic data of human and plants, the required material flow quantities between each subsystem in order to keep the appropriate condition for human and plants have been estimated. For promoting such fundamental researches on these subsystems and for planning the installation of test beds to check the closed loop life support function, new institute, Institute for Environmental Sciences, has been established in the end of last year.

Carbon Dioxide↗

PubMed1992

Effects of bilateral jugular vein ligation on intracranial pressure and cerebrospinal fluid outflow resistance in cats.

In order to study the effect of jugular venous outflow obstruction on intracranial pressure and cerebrospinal fluid (CSF) reabsorption capability, changes in epidural pressure (EDP) and CSF outflow resistance (Ro) were examined following bilateral jugular vein ligation in cats. EDP increased significantly (P less than 0.01) immediately after ligation from the control value of 4.9 +/- 0.5 mmHg (mean +/- SEM) to 15.9 +/- 0.9 mmHg. Thereafter, EDP gradually decreased back toward the control value. The pressure level had decreased to 6.7 +/- 0.5 mmHg by 20 minutes after ligation. The mean Ro was significantly (P less than 0.01) higher in the ligation group (200.4 +/- 9.7 mmHg/ml/min) that in the non-ligation group (120.0 +/- 9.9 mmHg/ml/min). These results suggest that bilateral jugular vein ligation impairs CSF reabsorption.

Absorption↗

PubMed1992

Interface problems between material recycling systems and plants.

A most important problem to creating a CELSS system to be used in space, for example, for a Lunar Base or Manned Mars mission, seems to be how to design and operate the various material recycling systems to be used on the missions. Recent studies of a Lunar Base habitat have identified examples of CELSS configurations to be used for the Plant Cultivation Module. Material recycling subsystems to be installed in the Plant Cultivation Modules are proposed to consist of various sub-systems, such as dehumidifiers, oxygen separation systems, catalytic wet oxidation systems, nitrogen adjusting systems, including tanks, and so on. The required performances of such various material recycling subsystems are determined based on precise metabolic data of derived from the various species of plants to be selected and investigated. The plant metabolic data, except that for wheat and potato, has not been fully collected at the present time. Therefore, much additional plant cultivation data is required to determine the performances of each material recycling subsystem introduced in Plant Cultivation Modules.

Carbon Dioxide↗

PubMed1992

Evaluations of catalysts for wet oxidation waste management in CELSS.

A wet oxidation is considered to be one of the most effective methods of waste processing and recycling in CELSS (Controlled Ecological Life Support System). The first test using rabbit waste as raw material was conducted under a decomposition temperature of 280 degrees C for 30 minutes and an initial pure oxygen pressure of 4.9 MPa (50 kgf/cm2) before heating, and the following results were obtained. The value of COD (Chemical Oxygen Demand) was reduced 82.5% by the wet oxidation. And also the Kjeldahl nitrogen concentration was decreased 98.8%. However, the organic carbon compound in the residual solution was almost acetic acid and ammonia was produced. In order to activate the oxidation more strongly, the second tests using catalysts such as Pd, Ru and Ru+Rh were conducted. As the results of these tests, the effectiveness of catalysts for oxidizing raw material was shown as follows: COD and the Kjeldahl nitrogen values were drastically decreased 99.65% and 99.88%, respectively. Furthermore, the quantity of acetic acid and ammonia were reduced considerably. On the other hand, nitrate was showed a value 30 times as much as without catalytic oxidation.

Aluminum Oxide↗

PubMed1992

A study of biohazard protection for farming modules of lunar base CELSS.

For the Closed Ecological Life Support System (CELSS) of a manned lunar base which is planned to be built on the moon early in the 21st century, several proposed programs exist to grow vegetables inside a farming module. At the 40th IAF (Malaga, 1989) the author et al presented a proposal for supplying food and nutrients to a crew of eight members, a basic concept which is based on growing four kinds of vegetables. This paper describes measures for biohazard protection in farming modules. In this study, biohazard protection means prevention of the dispersion of plant diseases to other plant species or other portions of farming beds.

Agriculture↗

PubMed1992

Carbon dioxide and oxygen budgets of a plant cultural system in a CELSS--a case of cultivation of lettuce and turnips.

In order to collect basic data about CO2 and O2 budgets of a plant cultural system in a CELSS, the variation of the CO2 absorption rates of lettuce and turnips were observed during the growing period, under different conditions. The O2 release rates were deduced from the CO2 absorption rates multiplied by 32/44. As a result, when the light intensity, the photoperiod and the atmospheric CO2 concentration increased, the rates also increased. The effects on the turnips were more significant than those on the lettuce. Turnips at 310 micromoles/m2/s of PPFD, 24 hours of photoperiod and 1100 ppm of CO2 concentration grew most actively in the present experimental conditions. One turnip absorbed 32.3 g CO2 and released 23.5 g O2 for 6 days between 24 days and 30 days after sowing.

Carbon Dioxide↗

PubMed1992

Different profiles of induced cotton effects of human and bovine lactoferrin by cibacron blue F3GA binding.

1. The properties of complex formation of lactoferrin with Cibacron Blue F3GA dye have been studied by circular dichroic spectral analyses. The Cotton effects were induced by the interaction of lactoferrin with the dye and occurred in the wavelength range from 300 to 450 nm. 2. The patterns of changes in circular dichroic spectra of lactoferrin induced by the dye were different in bovine and human lactoferrin. 3. Iron ions bound to lactoferrin affected the profiles of induced Cotton effects in human lactoferrin but not in bovine lactoferrin. 4. While the dye bound co-operatively to human apo-lactoferrin, such co-operativeness was not observed in iron-saturated human lactoferrin.

Animals↗

PubMed1992

Crystallization and preliminary X-ray structure analysis of pigeon egg-white lysozyme.

Calcium binding lysozyme from pigeon egg-white was crystallized by the hanging drop vapor diffusion technique using ammonium sulphate as a precipitant. The crystals belong to the orthorhombic system, space group P2(1)2(1)2(1), and have unit cell dimensions of a = 34.2 A, b = 34.8 A, and c = 99.4 A. One asymmetric unit contains one molecule of the pigeon lysozyme. The crystals diffract X-rays at least to 2.0 A resolution and are suitable for high resolution structure analysis. The diffraction data up to 3.0 A resolution were collected with a diffraction image processor, DIP100, using a Fuji imaging plate as an area detector. The structure was solved by the molecular replacement technique and refined to an R factor of 0.216. Least-squares fitting of the main-chains of pigeon egg-white lysozyme with those of chicken egg-white lysozyme and baboon alpha-lactalbumin showed that the main-chain folding of pigeon lysozyme is more similar to that of chicken lysozyme than that of alpha-lactalbumin. The largest differences between the pigeon and chicken lysozymes are in the surface loop regions.

Amino Acid Sequence↗

PubMed1992

Crystallographic studies of a calcium binding lysozyme from equine milk at 2.5 A resolution.

The crystal structure of a calcium binding equine lysozyme has been determined at 2.5 A resolution by means of molecular replacement. The energy minimized equine lysozyme as the starting model, was refined with the molecular dynamics program, X-PLOR, and the R factor of the current model was found to be 24% without any water molecules. The conformation of the calcium binding loop is similar to that of alpha-lactalbumin. The profiles of backbone atomic displacements throughout the lysozyme and alpha-lactalbumin superfamilies are comparable as well as their homologous tertiary structures.

Amino Acid Sequence↗

PubMed1992

Exogenous porcine surfactant (Curosurf) is inactivated by monoclonal antibody to the surfactant-associated hydrophobic protein SP-B.

A monoclonal antibody to the surfactant-associated hydrophobic protein SP-B was added at various concentrations to a standard preparation of porcine surfactant (Curosurf 10 mg/ml), and surface properties were evaluated with pulsating bubble. Retarded adsorption of surfactant was observed at antibody concentrations > or = 0.5 mg/ml and significantly increased values for minimum surface tension were observed at antibody concentrations > or = 1 mg/ml. In vivo effects of the antibody were tested in immature newborn rabbits ventilated with a standardized sequence of insufflation pressures. Animals receiving 0.1 ml surfactant (80 mg/ml) mixed with antibody at concentrations > or = 4 mg/ml had low tidal volumes, poor lung stability in pressure-volume recordings, poor alveolar expansion in histological sections and widespread epithelial necrosis in peripheral airways. Admixtures of IgG had no such effects. We conclude that this monoclonal antibody inactivates exogenous porcine surfactant, probably by preventing fast adsorption of surfactant lipids to the alveolar air-liquid interfaces.

Adsorption↗

PubMed1992

[The comparison of alkalizing methods in dogs during the immediate postresuscitation period].

The purpose of this study is to determine the effects of sodium bicarbonate (SB) on acid-base balance in dogs during immediate post-resuscitation period when tissue blood flow is decreased. Anesthetized dogs underwent 6 min of cardiac arrest plus 8 min of open chest CPR. Treatments with SB (0.1 mEq.kg-1.min-1), THAM (0.1 mEq.kg-1.min-1) and hyperventilation (TV = 20 ml.kg-1, RR = 20) were performed for 1h after restoration of spontaneous heart beat. Immediately after resuscitation, the following data were obtained; arterial (a) pH 7.17, PaCO2 37.8 mmHg, aHCO3- 13.2 mEq.l-1, venous (v) pH 7.09, PvCO2 57.5 mmHg, vHCO3- 16.6 mEq.l-1, CSF (c) pH 7.27, PcCO2 41.4 mmHg, cHCO3- 18.6 mEq.l-1, serum osmotic pressure (SOP) 310 mOsm.kg-1, and serum lactate (SL) 24.8 mg.dl-1. Metabolic acidosis in control group (no alkalizing agent, normoventilation) was not corrected within 120 min. In SB group, apH, aHCO3-, cpH and cHCO3- improved in 15-45 min after starting SB treatment. SL increased markedly (twice control group) which is attributable to CO2 production by SB in low flow state. SOP also increased to 320 mOsm.kg-1 by 120 min, with associated serum Na increase. In THAM group apH, PaCO2, aHCO3-, cpH and cHCO3- improved as in SB group. SOP rose to 324 mOsm.kg-1. No SL increase was observed. In hyperventilation group apH and aHCO3- were not normalized. PcCO2 and cpH were normalized earliest among the groups. SL changes were similar to that of control group. The author concludes that SB administration during immediate postresuscitation period may not be beneficial for treatment of acid-base balance.

Acid-Base Equilibrium↗

PubMed1992

Surgical treatment for renal hyperparathyroidism--report of 23 cases.

The present study describes surgical resection in 23 patients under maintenance hemodialysis with hyperparathyroidism. Twenty-three patients under maintenance hemodialysis had subtotal parathyroidectomy (s-PTx, n = 12) or parathyroid gland transplantation combined with total parathyroidectomy (Tx, n = 11) performed from January 1979 to January 1991. Their ages ranged from 8 to 63 years. The PTH levels were elevated in all patients preoperatively from 2.5 to 120 times over the upper limit of normal. After s-PTx, PTH levels sharply declined in all but one patient. Clinical symptoms improved in 11 cases with PTH decrease. After Tx, an abrupt decline in PTH was observed after surgery in 10 patients. One patient was reoperated because of persistent hyperparathyroidism. Another patient showed a PTH increase 13 months after surgery. The transplanted parathyroid gland was subtotally resected. Five months after reoperation, the condition recurred and the patient underwent total resection of the transplanted parathyroid gland and its re-autografting into the forearm. In the patients with renal hyperparathyroidism, s-PTx or Tx improved clinical symptoms; this indicates the high reliability of both procedures in treating the disease. A long-term follow-up study must be conducted to check the possible postoperative recurrence of hyperparathyroidism from residual and/or autograft parathyroid gland.

Adolescent↗

PubMed1991

Determination of calcium ions tightly bound to proteins.

A rapid and sensitive procedure is described for the determination of calcium ions tightly bound to proteins using high-performance gel filtration chromatography, followed by the destabilization of the protein conformation and fluorimetric analysis with Quin-2. With this method, contaminating, unbound calcium can be eliminated simultaneously and one can determine the content of a calcium ion in a protein utilizing less than 200 pmol of the protein.

Animals↗

PubMed1991

Purification and characterization of beta-galactoside binding lectin from frog (Rana catesbeiana) eggs.

A beta-galactoside-binding lectin, a homodimer composed of 14kDa subunits, was purified from unfertilized eggs of the frog Rana catesbeiana by asialofetuin-Sepharose 4B affinity column chromatography. The lectin was solubilized from eggs by addition of neither haptenic sugar nor detergent and showed a unique characteristic that it requires neither Ca++ nor SH-reagent for its hemagglutination activity. However, the partial amino acid sequence indicated that the lectin belongs to a family of soluble 14kDa beta-galactoside-binding lectins (14K-lectin) widely distributed in vertebrates and classified as S type lectins. These results indicate that a 14K-lectin is present as the free form in unfertilized frog eggs, presenting the first structural evidence for the presence of a soluble 14K-lectin in the amphibian eggs.

Amino Acid Sequence↗