Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 271 records · Page 15Linked to original sources

PubMed1993

Quantitative morphological analysis of the pituitary gland in protein-calorie malnourished rats.

A quantitative analysis of the pituitary gland was conducted to ascertain the effects of protein-calorie malnutrition on the morphology of the somatotrophs, gonadotrophs, thyrotrophs, and corticotrophs. Male rats were fed a low, 8% protein diet from 20 to 50 days of age, while their age-matched controls were given a diet containing 27% protein. The hypophyses were then processed for light microscopic immunocytochemical staining using antibodies to growth hormone, the beta subunits of luteinizing hormone and thyroid stimulating hormone, and adrenal corticotrophic hormone. The number of each cell type along with an evaluation of the cell, cytoplasmic, and nuclear areas was conducted using a computerized image analyzer. All of these parameters were reduced significantly in the somatotrophs as a result of the low protein diet, while in the gonadotrophs, the cell, cytoplasmic, and nuclear areas were similarly affected. Smaller cell number, cell area, and nuclear area were noted in the corticotrophs of the malnourished animals, while in the thyrotrophs, only the cell and nuclear areas were reduced. The data demonstrate that each pituitary cell type responds in a unique manner to undernutrition.

Adrenal Glands↗

PubMed1993

A novel recovery system for cultured cells using plasma-treated polystyrene dishes grafted with poly(N-isopropylacrylamide).

Poly(N-isopropyl acrylamide) (PIPAAm) demonstrated a fully expanded chain conformation below 32 degrees C and a collapsed, compact conformation at high temperatures. This unique temperature responsive polymer was grafted onto surfaces of commercial polystyrene dishes and used as temperature switches for creating hydrophilic surfaces below 32 degrees C and hydrophobic surfaces above 32 degrees C. Cell attachment and the growth of bovine endothelial cells and rat hepatocytes on PIPAAm-grafted surfaces at 37 degrees C demonstrated similar behavior to the commercialized culture dishes. Both cell types were observed to detach from the PIPAAm-grafted surface simply by reducing the temperature below the polymer transition temperature (collapse). Cells recovered by this method maintained substrate adhesivity, growth, and secretion activities nearly identical to those found in primary cultured cells in contrast to the compromised function found in cultured cells damaged by trypsinization. These results provide strong evidence that PIPAAm-grafted surfaces, as thermal switches are very effective for reversing cell attachment and detachment without cell damage. Properties of cell culture surfaces can be readily transformed by this technique reversibly into hydrophilic and hydrophobic coatings of PIPAAm-grafted polymers.

Acrylic Resins↗

PubMed1993

Prevention of changes in platelet cytoplasmic free calcium levels by interaction with 2-hydroxyethyl methacrylate/styrene block copolymer surfaces.

Changes in platelet cytoplasmic free calcium levels were investigated in contact with cast film surfaces of a block copolymer containing 2-hydroxyethyl methacrylate (HEMA) and styrene (St) (0.5 mole fraction HEMA). These copolymer surfaces demonstrate microdomain alternating lamellae structures composed of hydrophilic HEMA domains (5 nm width) and hydrophobic St domains (20 nm width). The results were compared with those obtained from platelets contacting a random copolymer of HEMA-St (0.5 mole fraction HEMA) and from homopolymers of polystyrene (PSt) and poly(2-hydroxyethyl methacrylate) (PHEMA). Cytoplasmic free calcium levels in platelets contacting the microdomain structured surfaces of the HEMA-St block copolymer remained relatively constant in contrast to the significant increases observed for the radically prepared HEMA-St copolymer, PSt, and PHEMA surfaces. Adhering platelets were stimulated by exogenously introduced thrombin and calcium ionophore A23187 20 min after platelet adherence to the polymer surfaces. Only platelets on the block copolymer surfaces showed active metabolic responses. These results suggest that adhering platelets on the microdomain structured surfaces maintain high sensitivities to external stimulation due to an intrinsic strong inhibition of platelet functional changes induced by surface contact.

Blood Platelets↗

PubMed1993

Histopathological study of hereditary cataractous lenses in SCR strain rat.

A new cataractous rat strain, Shumiya Cataract Rat (SCR), which was derived from the cross-breeder formed between the spontaneous hypertensive rat and the Zucker fatty rat, was studied by light and electron microscopy. The earliest change was the occurrence of some displaced nuclei in the posterior cortical fibres at birth. By 2 weeks of age, mild dysplasia of the anterior suture, aggregated epithelial cells overlying the sutural area, and poorly differentiated epithelial cells at the bow area were observable. At 3 weeks, unusually dense lens fibres near dense epithelial cells were found at the equator, and some epithelial cells showed accellularity after 4 weeks. Swelling and liquefaction of the lens fibres appeared in the anterior cortex by this stage. By 6 weeks, these changes extended toward the equatorial region. At 7 weeks, a sutural gap occurred at the anterior polar area, and this gap reached a maximum at 8 weeks. At this time, swelling of the posterior extremities of the lens fibres appeared, showing a small placoid opacity of the posterior subcapsular region under a dissecting microscope. At 10 weeks, small amounts of liquefaction were observed in this region. Between 10.5 and 11 weeks, as the posterior suture of liquefaction were observed in this region. Between 10.5 and 11 weeks, as the posterior suture separated, opacification appeared around the separated sutural area and rapidly developed into a mature cataract. The mechanism of cataract formation in the SCR rat lens may be associated with the continuous occurrence of a small proportion of poorly-differentiated epithelial cells at the bow area and sutural dysplasia of the anterior lens fibres.

Age Factors↗

PubMed1993

Hypothalamic-pituitary-adrenal axis function in children with attention-deficit hyperactivity disorder.

Examined hypothalamic-pituitary-adrenal axis (HPA axis) function in 30 children with attention-deficit hyperactivity disorder (ADHD) by measuring the diurnal variation and response to the dexamethasone suppression test (DST) of saliva cortisol. Normal diurnal saliva cortisol rhythm was found in only 43.3% of the ADHD children. DST showed suppression in 46.7% of the ADHD children. An abnormal diurnal rhythm and nonsuppression to the DST were more frequent in the severely hyperactive group than in the mildly were more frequent in the severely hyperactive group than in the mildly hyperactive group of children with ADHD. These results suggest abnormalities in HPA axis function in some children with ADHD, especially those exhibiting severe hyperactivity.

Attention Deficit Disorder with Hyperactivity↗

PubMed1993

Analysis of micelle formation of an adriamycin-conjugated poly(ethylene glycol)-poly(aspartic acid) block copolymer by gel permeation chromatography.

The micelle-forming behavior of a drug-block copolymer conjugate (adriamycin-conjugated poly(ethylene glycol)-poly(aspartic acid) block copolymer; PEG-P[Asp(ADR)]) was analyzed by gel permeation chromatography (GPC). Four compositions of the conjugates were observed to form micellar structures in aqueous media, and their micelle-forming behavior was found to be dependent on the composition and media. These micelles did not reach equilibrium within short time periods like low molecular weight surfactants. One composition formed stable micelles in the presence of serum.

Animals↗

PubMed1993

Biodistribution of micelle-forming polymer-drug conjugates.

Polymeric micelles have potential utility as drug carriers. To this end, polymeric micelles based on AB block copolymers of polyethylene oxide (PEO) and poly(aspartic acid) [p(Asp)] with covalently bound Adriamycin (ADR) were prepared. The micelle forming polymer-drug conjugates [PEO-p(Asp(ADR)] were radiolabeled and their biodistribution was investigated after intravenous injection in mice. Long circulation times in blood for some compositions of PEO-p[Asp(ADR)] conjugates were evident, which are usually atypical of colloidal drug carriers. This was attributed to the low interaction of the PEO corona region of the micelles with biocomponents (e.g., proteins, cells). Low uptake of the PEO-p(Asp(ADR)] conjugates in the liver and spleen was determined. The biodistribution of the PEO-p[Asp(ADR)] conjugates was apparently dependent on micelle stability; stable micelles could maintain circulation in blood, while unstable micelles readily formed free polymer chains which rapidly underwent renal excretion. Long circulation times in blood of PEO-p(Asp(ADR)] conjugates are thought to be prerequisite for enhanced uptake at target sites (e.g., tumors).

Animals↗

PubMed1993

Swelling controlled zero order and sigmoidal drug release from thermo-responsive poly(N-isopropylacrylamide-co-butyl methacrylate) hydrogel.

Thermo-responsive hydrogels of poly(N-isopropylacrylamide-co-butyl methacrylate) (poly-(IPAAm-co-BMA)) are capable of swelling-deswelling changes in response to external temperature. As poly(IPAAm-co-BMA) gels swell larger at a lower temperature, the degree and rate of the swelling could be controlled by temperature without altering the chemical structure. Therefore, drug release profiles were remarkably changed by alternation of temperature. The release profiles of indomethacin from poly(IPAAm-co-BMA) were observed to be zero-order at 20 degrees C. This release profile was explained in terms of a Case-II diffusion mechanism; which indicates relaxation of polymer chains with swelling was rate-determining. In the case of 10 degrees C, release demonstrated a sigmoidal profile. The acceleration of drug release was due to a rapid increase in swelling with disappearance of the glassy core which had constrained swelling. The regulation of the water-uptake process by changing external temperature remarkably affected drug release and resulted in several different release profiles.

Acrylic Resins↗

PubMed1993

Mechanism of cytoplasmic calcium changes in platelets in contact with polystyrene and poly(acrylamide-co-methacrylic acid) surfaces.

Changes in cytoplasmic free calcium levels ([Ca2+]i) in platelets in contact with polystyrene (PSt) and poly(acrylamide-co-methacrylic acid) (PAAmMAc) particles were evaluated and results were compared with those from two representative biological calcium agonists; thrombin and calcium ionophore A23187. PSt particles stimulated a steep increase in cytoplasmic calcium levels in platelets as much as thrombin and A23187. Serratia protease-treated platelets showed a steep increase in [Ca2+]i by PSt particles, suggesting that PSt surfaces can initiate platelet activation independent of a glycoprotein Ib (GPIb)-mediated pathway. By contrast, dibucaine-treated platelets showed little increase in [Ca2+]i by PSt particles, indicating that microfilament assembly, including binding of GPIb with actin binding protein, should be required for platelet activation in contact with PSt surfaces. PAAmMAc particles induced little increase in cytoplasmic calcium levels in platelets. However, PAAmMAc particle-treated platelets demonstrated little response to thrombin in terms of an increase in [Ca2+]i and ATP release, suggesting the possibility that PAAmMAc surfaces may regulate [Ca2+]i by influencing platelet metabolism. Furthermore, sodium azide-treated platelets showed an increase in [Ca2+]i in platelets when contacting PAAmMAc particles, supporting the suggestion that PAAmMAc surfaces could regulate platelet functions. Fluorescence polarization measurements using 1,6-diphenyl-1,3,5-hexatriene-loaded platelets revealed that PAAmMAc particles increased membrane fluidity in platelets, which may be due to physicochemical interaction with PAAmMAc surfaces.

Acrylic Resins↗

PubMed1993

p-Aminohippurate transport in rat renal brush-border membranes: a potential-sensitive transport system and an anion exchanger.

Transport mechanisms of p-aminohippurate (PAH) were investigated in rat renal brush-border membrane vesicles. The uptake of PAH was stimulated by an inside-positive membrane potential created by K+ and valinomycin. This potential-stimulated uptake of PAH was inhibited by various anion transport inhibitors and was saturable. In addition, PAH uptake in the presence of valinomycin was linearly increased in proportion to log[K+]out/[K+]in. On one hand, PAH uptake was stimulated by [14C]PAH/PAH or [14C]PAH/Cl- exchange, and the [14C]PAH/PAH exchange was insensitive to the membrane potential. The uptake by the exchanger was also inhibited by anion transport inhibitors, but the potential-stimulated uptake of PAH was more sensitive to furosemide and 4,4'-diisothiocyano-2,2'-disulfonic stilbene. On the contrary, [14C]PAH/PAH exchange was more sensitive to urate than the potential-stimulated uptake of PAH. These findings indicate that PAH is transported by two distinct transport systems in rat renal brush-border membranes, a potential-sensitive transport system and an anion exchanger.

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

PubMed1993

Exposure reduction in cephalography with a digital photostimulable phosphor imaging system.

The effect on the determination of the cephalometric landmarks of exposure reduction using computed radiography with a photostimulable storage phosphor was evaluated. Forty patients attending for regular review were divided into four groups of 10. The first group was exposed to the same amount of radiation as that required for a conventional calcium tungstate screen-film combination. The other three groups were exposed to approximately 50, 20 and 10% respectively of the radiation dose of the first group. Ten dentists determined the landmarks. The coordinates of the points were recorded to measure the consistency of landmark identification. It was found that in comparison with the conventional screen-film system, a substantial reduction of exposure could be achieved with computed radiography for cephalography without clinical detriment.

Adolescent↗

PubMed1993

Cell-mediated immunity in bronchial asthma evaluated by purified protein derivative- and Candida albicans-skin reaction.

Cell-mediated immunity was examined in 45 patients with bronchial asthma by observing the delayed cutaneous reaction to purified protein derivative (PPD) and Candida albicans (C. albicans). The delayed skin reaction to PPD showed a decrease with age starting between 50 and 59 years old. The delayed reaction to PPD decreased more prominently with aging, being significantly depressed in the patients aged over 70 years than in those aged between 30 and 49 years (induration, p < 0.02; flare, p < 0.01). The C. albicans-induced skin reaction was significantly lower in the patients aged over 70 years than in those between 60 and 69 years old (induration, p < 0.01; flare, p < 0.05). The delayed skin reaction to PPD and C. albicans was significantly depressed in the patients with a serum IgE level over 1001 IU/ml. Delayed skin reaction to PPD and C. albicans was more depressed with aging and an elevated serum IgE, and the age (50-59 years) at the initiation of depression in the PPD-induced delayed skin reaction was younger than that (over 70 years) in the C. albicans-induced reaction.

Adult↗

PubMed1993

A new modified classification of bronchial asthma based on clinical symptoms.

The clinical features of four asthma types, Ia-1 (bronchospasm with 0-49 ml/day of expectoration), Ia-2 (with 50-99 ml/day), Ib (over 100 ml/day), and II (bronchiolar obstruction), as classified by the clinical symptoms, were compared in 119 patients with bronchial asthma. The age of onset characteristic symptoms of each asthma type was in the 20's in types Ia-1 and Ia-2, in the 30's in type Ib, and in the 40's in type II patients. A significant increase in the number of neutrophils in bronchoalveolar lavage (BAL) fluid was found in type II patients. The proportion of BAL eosinophils was significantly higher in types Ia-2 and Ib asthma patients compared with that in type Ia-1 patients. The BAL eosinophil count was significantly higher in type Ib than in type Ia-2 patients. The FEV1.0% and %V25 values were significantly lower in patients with type II asthma than in the patients with the other asthma types. Steroid-dependent intractable asthma (SDIA) was more often observed in patients with type Ib or type II asthma.

Adolescent↗

PubMed1993

Gross and separative determination of 1 alpha,25-dihydroxyvitamin D2 and D3 in plasma using calf thymus receptor.

Determination of 1 alpha,25-dihydroxyvitamin D [1,25(OH)2D, gross amounts of 1,25(OH)2D2 and 1,25(OH)2D3] and separative determination of 1,25(OH)2D2 and 1,25(OH)2D3 in plasma using calf thymus receptor have been investigated. A lipid extract from 1 ml of plasma is applied to a Bond Elut C18OH column and an eluate corresponding to 1,25-(OH)2D including both 1,25(OH)2D2 and 1,25(OH)2D3 is applied to calf thymus receptor to assay a gross amount of the two compounds. On the other hand, when separative assay of the two compounds is performed, the 1,25(OH)2D eluate obtained from the Bond Elut C18OH column is further applied to HPLC using a Zorbax SIL column with 5% isopropanol in methylene chloride as a developing solvent to separate the two compounds from one another. The separated eluates are independently applied to the receptor to assay the two compounds. Since less amounts of unknown components non-specifically bound to interfering concomitants besides 1,25(OH)2D exist in the calf thymus receptor, complicated purification steps to eliminate the concomitants are unnecessary. The detection limit by this method is 1.25 pg/tube which is sensitive enough for a routine method to assay 1,25(OH)2D in plasma.

Animals↗

PubMed1993

[Preoperative grading of renal cell carcinoma by plasma immunosuppressive acidic protein level and tumor diameter using discriminant analysis].

To predict histological grade of renal cell carcinoma preoperatively, an equation using plasma immunosuppressive acidic protein (IAP) level and tumor diameter was proposed. Between April 1977 and December 1991, 281 patients, 195 males and 86 females, aged between 20 and 84-year-old, were operated at our institutions. Multivariate analysis was performed to detect relationship between tumor grade and various factors that have continuous quantity. Among plasma components tested, plasma IAP levels showed the best correlation with grade (r value = 0.526, n = 157). Tumor diameter also showed correlation with grade (r value = 0.476, n = 273). Therefore, these two factors were used as variates. Discriminant analysis was applied to differentiate the patients with grade 1 or grade 2 tumor from those with grade 3 ones. From this analysis the linear function was obtained; z = 6.9429 - 0.0048x1 - 0.4118x2 (x1: IAP (micrograms/ml), x2: diameter (cm)). Tumor was assumed to be grade 1 or grade 2 when z value was positive, and it was assumed to be grade 3 when z value was negative. Overall accuracy was 87.7%. Positive predictive value of grade 1 or grade 2 tumor, and grade 3 tumor was 91.7% and 77.8%, respectively. Sensitivity was 90.9% for grade 1 or grade 2 tumor, and 79.5% for grade 3 tumor. As a result, it's possible to estimate tumor grade before operation using discriminant analysis in patients with renal cell carcinoma.

Adult↗

PubMed1993

Airway inflammation and bronchial hyperresponsiveness in patients with asthma. Comparison between atopic and nonatopic asthma.

A relationship of cellular composition in the airways and the release of chemical mediators from the cells to bronchial hyperresponsiveness was examined in two age-matched asthma groups: 15 atopic and 15 nonatopic patients. 1. A significant correlation between the proportion of eosinophils in bronchoalveolar lavage (BAL) fluid and bronchial reactivity (BR) was found in patients with atopic and nonatopic asthma. The proportion of the cells (combined eosinophils and neutrophils) in BAL fluid was closely correlated with BR in patients with atopic asthma, but not in those with nonatopic asthma. There was no correlation between the proportion of BAL neutrophils and BR in the two asthma groups. 2. There was a significant correlation between histamine release from BAL cells and BR in patients with atopic asthma. In contrast, LTC4 release from BAL cells was significantly corrected with BR in patients with nonatopic asthma. The results suggest that the humoral and cellular components in the airways, that participate in bronchial hyperresponsiveness, are different between patients with atopic and nonatopic asthma.

Adult↗

PubMed1993

[Development of intelligent DDS technologies].

Recently, biologically active therapeutic peptides have been artificially synthesized by genetic engineering techniques. These peptides are easily degraded under physiological conditions and also encounter absorption problems due to their high molecular weight. Hence, they cannot be utilized effectively in conventional dosage forms. For such active agents, new types of DDS must be developed to deliver the drug effectively to the target site (targeted, site-specific delivery) and release drug when drug is required (temporal control) in addition to conventional rate-controlling systems. To realize such drug release systems, it is important to construct a system where drug itself senses an environmental stimuli and responds to appropriately control drug release. Such systems are described as "intelligent DDS", as distinguished from conventional DDS.

Drug Delivery Systems↗

PubMed1993

[Fistula between iliac artery aneurysm and ureter: a case report and review of the literature].

We report a patient who developed a fistula between the right ureter and the right common iliac artery aneurysm. He had had replacement of a synthetic graft for abdominal aortic aneurysm sixteen years previously. The diagnosis was confirmed by angiography, retrograde pyelography and computed tomography. The fistula was treated by right nephroureterectomy and resection of right common iliac artery aneurysm. A brief description of the case is provided and the review of the literature is described.

Aged↗