Search PubMed⌕ Search

Biomedical subjects

N Tada

Publications and source records attributed to N Tada.

At least 55 records · Page 3Linked to original sources
PubMed1996

Successful vitrification of stroke-prone spontaneously hypertensive and normal Wistar rat 2-cell embryos.

Stroke-prone spontaneously hypertensive rats (SHRSPs) have been widely used as models of hypertension and cerebral apoplexy. They were obtained by selective sib-breeding of Wistar Kyoto rats with higher blood pressure than rats of the original Wistar Kyoto strain. For vitrification of SHRSP 2-cell embryos, DPS solution containing 2.75 M dimethylsulfoxide, 2.75 M propylene glycol and 1.0 M sucrose was prepared and diluted in a modified phosphate-buffered saline, PB1, containing 0.3% bovine serum albumin. Embryos were exposed to the resulting solution in one step at room temperature, kept in the solution for 15 s, vitrified in liquid nitrogen, and warmed rapidly. The post-warming survival rate as morphologically assessed was 70% (148/210), which was comparable (P > 0.05) to the rate of 88% (78/89) for the solution control. After vitrification, the embryos were transferred into recipient animals, and 62% (48/78) were normally delivered, comparable (P > 0.05) to the percentage for the solution control (68%, 57/84). These was no significant difference between pups from vitrified embryos and those from unvitrified control embryos in either the growth curve or degree of blood pressure increase. These findings demonstrate the effectiveness of the simple vitrification method we used for cryopreservation of SHRSP and Wistar rat 2-cell embryos, and also demonstrate that vitrification-mediated cryopreservation does not affect the phenotypic characteristics of SHRSPs.

Animals↗
PubMed1996

Dose-dependent effect of niceritrol on plasma lipoprotein-a.

Lipoprotein-a, Lp(a), is a variant form of low density lipoprotein (LDL) that contains apolipoprotein-a, whose structure has 75-85% homology with plasminogen. Elevated plasma levels of Lp(a) are considered to be one of the independent risk factors for cardiovascular disease. We studied the effects of niceritrol, a nicotinic acid derivative, on plasma Lp(a) levels in 72 patients with hypercholesterolaemia. The dose of niceritrol was increased every 4 weeks, from 750 to 1500 and then to 2250 mg day-1. The final dose was adjusted to obtain a plasma cholesterol level less than 5.69 mmol l-1. Niceritrol led to significant decreases in plasma levels of median Lp(a), from 16.1 mg dl-1 (interquartile intervals, 8.7 to 32.8) to 11.1 mg dl-1 (interquartile intervals, 6.6 to 21), the mean reduction rate being 17.6%. In the group with pretreatment Lp(a) levels of over 20 mg dl-1, Lp(a) decreased by 10.0, 22.0 and 31.8% at the doses of 750, 1500, and 2250 mg day-1, respectively. In the group with levels less than 20 mg dl-1, only the dose of 2250 mg day-1 was effective in the reduction of Lp(a). The results suggest that the reduction of Lp(a) was dependent on the dose of niceritrol and on the pretreatment level of Lp(a). In conclusion, niceritrol is effective, in a dose-dependent manner, for reducing Lp(a) levels.

Aged↗
PubMed1995

Preferential expression of osteocalcin-related protein mRNA in gonadal tissues of male mice.

It was recently reported that the mouse genome contains an osteocalcin cluster formed by three genes, OG1, OG2 and ORG, in order from the 5' to the 3' end of the cluster. These three genes exhibit close structural homology. OG1 and OG2 are abundant in bone, but ORG is expressed in nonosteoid tissues, especially in kidney and lung. Previous studies using transgenic mice carrying diphtheria toxin A-chain gene linked to the rat osteocalcin (OG2) promoter have revealed that the OG2 promoter is active not only in osteoblasts, but also in testis. In this study, reverse transcription-polymerase chain reaction was used to study the expression of these three genes in mouse tissues (including testis). Here we report for the first time that mouse ORG is extensively transcribed in male gonadal tissues including seminal vesicle, preputial gland, testis, caput epididymis and cauda epididymis. These findings suggest that ORG may play a role in differentiation and/or maintenance of male gonadal tissues.

Animals↗
PubMed1995

Production of transgenic mice by microinjection of DNA into vitrified pronucleate stage eggs.

Vitrification is a technique for cryopreserving cells without crystallization due to elevation of the viscosity during the cooling process. We have developed a rapid and convenient mean of cryopreserving mouse preimplantation embryos by vitrification using a solution (hereafter named DPS) consisting of 2.75 M dimethylsulfoxide, 2.75 M propylene glycol and 1.0 M sucrose. In vitro fertilized pronucleate stage eggs were used because a large number of stage-matched eggs can be obtained at once. Only successfully fertilized eggs were collected and vitrified in DPS. After warming, two DNA constructs were injected into a total of 257 cryopreserved eggs, of which 175 (68%) survived the injection and were transferred into six recipients. All recipients became pregnant and gave birth to a total of 20 pups. When these DNA constructs were concomitantly injected into fresh eggs, 18% of eggs that were transferred developed into live pups, which was the same as the 18% figure for the cryopreserved eggs. With respect to transgenesis, 40% of the pups (8/20) developed from vitrified eggs were transgenic. In terms of the injected eggs that had been transferred, 4.5% of the 213 fresh eggs and 3.1% of the 112 vitrified eggs developed into transgenic mice. These results indicate that the efficiency of production of transgenic mice from vitrified eggs is comparable to that from fresh eggs.

Animals↗
PubMed1995

High retinol/retinol-binding protein ratio in noninsulin-dependent diabetes mellitus.

The authors evaluated serum retinol, retinol-binding protein (RBP), and beta-carotene levels to elucidate the retinoid metabolism in non-insulin-dependent diabetes mellitus (NIDDM). The mean retinol levels by gender (1.83 mumol/L for females and 2.24 mumol/L for males) in diabetics were higher than those (1.31 mumol/L for females and 1.82 mumol/L for males) in control subjects (P < 0.0001, P < 0.01, respectively). The mean retinol/RBP ratios (0.95 for females and 0.97 for males) of diabetics were higher than those of the control subjects (0.60 for females and 0.64 for males) and of male patients having impaired glucose tolerance (0.55) (P < 0.0001). Lipid-lowering medication significantly decreased retinol, with decreasing apolipoprotein C-II but without a commensurate decrease in RBP. The retinol levels had a positive correlation with apolipoprotein C-II in all or normolipidemic patients with diabetes and control subjects. The high retinol/RBP ratio implies that an excessive or free retinol possibly exists in NIDDM. An alternative metabolism of retinol is inferred to underlie NIDDM without direct influences of cholesterol or triglyceride themselves.

Anticholesteremic Agents↗
PubMed1995

[Artificial insemination using the husband's frozen sperm in a patient with chronic myelogenous leukemia after bone marrow transplantation].

A 37-year-old man with chronic myelogenous leukemia (CML) was scheduled to receive a bone marrow allograft from an HLA-matching sibling. He was married without children, and desired to have a child in the future. Sperm was collected before transplantation and frozen for preservation. Induction therapy performed using 8 mg/kg of busulfan, 120 mg/kg of cyclophosphamide, splenic irradiation (4.5Gy), and total body irradiation (10Gy), and then allogenic bone marrow transplantation (BMT) was carried out. His post-transplantation course was uneventful and cyclosporin therapy was finished on day 187. The Philadelphia chromosome disappeared on day 20 after BMT and PCR analysis was negative for the bcr/abl rearrangement, suggesting the possibility of cure. Accordingly, artificial insemination was attempted using the frozen sperm. His wife became pregnant after the 4th attempt and a healthy baby was delivered. Transplantation recipients often become sterile because they receive ultra-high doses of chemotherapy and irradiation. However, it is still possible to have children if sperm or ova are preserved prior to transplantation. This is thought to improve the quality of life after BMT.

Adult↗
PubMed1995

[Remnant-like particles-cholesterol (RLP-C) assay and its clinical application to lipid tests in a postprandial as well as fasting state].

It was during the past few years that postprandial hyperlipidemia is believed to be more closely related to a risk for coronary artery disease. However, the high variability in the postprandial triglyceride (TG) levels could have made overlooked such diagnostic value in estimating an individual's risk for coronary artery disease. To minimize the impact of such variability, the remnant lipoproteins, TG-rich lipoproteins, might be measured in cholesterol using remnant-like particles (RLP-C) assay as a more reliable marker. In place of the previous cholesterol reagent (CHOD-Iodine) in RLP-C assay, the RLP-C assay was improved by employing a new cholesterol reagent (POD-EMSE). The correlation between these two assays was high (r = 0.978). The variations in RLP-C levels in healthy normolipidemic subjects was within 7.5mg/dl in a day. In oral-fat loading test, the variations of RLP-C levels in healthy subjects were also within 7.5mg/dl. However, patients with coronary artery disease showed much higher levels (over 7.5mg/dl) of RLP-C during the test. In conclusion the RLP-C assay can be used for the measurement of remnant lipoproteins in serum prepared from the fasting as well as postprandial states for predicting subjects who may be at risk of coronary artery disease.

Adult↗
PubMed1994

A new approach for the detection of type III hyperlipoproteinemia by RLP-cholesterol assay.

Type III is a remnant hyperlipoproteinemia identified by the presence of beta-VLDL (remnant lipoprotein) as well as a genetic variant of apo E (apo E2/2). The RLP isolated from the serum of Type III patients by a new method we have developed, the RLPcholesterol assay, was identified as chylomicron and VLDL remnant. In addition, the RLP-C levels of the Type III patients were significantly higher than other hyperlipidemic patients with similar serum TG levels, while the ratio of TC/TG in RLP-C of both groups was not significantly different. The RLP-cholesterol assay appears to be useful for the screening and monitoring of Type III hyperlipoproteinemia when used in conjunction with the assays of serum TG level and genetic apo E isoform analysis.

Adult↗
PubMed1994

[LDL receptor gene analysis and phenotypic variation of familial hypercholesterolemia].

Familial hypercholesterolemia, one of the most common single-gene disease in which defective catabolism of LDL is responsible for the increased plasma cholesterol and leads to the deposition of cholesterol in the arterial wall and premature coronary artery disease, is caused by inherited defects in the gene for the low density lipoprotein receptor. Clinical variation is known to exist in familial hypercholesterolemia. Since cloning of the human LDL receptor gene, it has been revealed that the nature of the LDL receptor gene mutation contributes to these clinical variability of familial hypercholesterolemia. Other mutations not linked to LDL receptor gene, such as apo E, apo B and several growth factor genes, and environmental factors may also be related to the severity of symptom or response to the treatment in familial hypercholesterolemia. Further study in the molecular biological field using knock-out and transgenic expression techniques is needed to elucidate the key factors which influence the clinical varieties of expression in familial hypercholesterolemia and to develop the new methods for treatment.

Genetic Variation↗
PubMed1993

Cholesterol in remnant-like lipoproteins in human serum using monoclonal anti apo B-100 and anti apo A-I immunoaffinity mixed gels.

We have developed a simple, rapid assay method for apo E-rich lipoproteins (d < 1.006 g/ml), using an immunoaffinity gel mixture of anti apo B-100 and apo A-I antibodies coupled to Sepharose 4B. The immunoaffinity mixed gels adsorb normal lipoproteins containing apo A-I quantitatively as well as most lipoproteins containing apo B-100. Unbound lipoproteins are quantified by assay of cholesterol. Characterization of the unbound lipoproteins of d < 1.006 g/ml (J Lipid Res 1992; 33: 369-380) has shown that they represent chylomicron and VLDL remnant-like particles (RLP). RLP-Cholesterol(C) levels in plasma have been determined in 363 male and female normolipidemic subjects (mean +/- S.D.: 72 +/- 16 mg/l) and have been found to be higher in patients with coronary heart disease and familial dysbetalipoproteinemia. Triglyceride-rich lipoproteins may well contain both atherogenic and non-atherogenic particles that can be separated by this simple immunoadsorption assay.

Adolescent↗
PubMed1993

Antimicrobial activity of lipoprotein particles containing apolipoprotein Al.

Human plasma in vitro inhibits the growth of coagulase negative staphylococci, S. epidermidis, which may be pathogenic in the immunocompromised host. To determine the antimicrobial components, serum was fractionated by column chromatography, which revealed that elution areas where lipoproteins can be yielded had high antimicrobial activity against S. epidermidis. Therefore, lipoprotein fractions, including very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL), were separated by ultracentrifugation and incubated with S. epidermidis. All 3 lipoprotein fractions suppressed bacterial growth within the first 3 h but VLDL enhanced bacterial growth after 9 h of incubation compared with the control. HDL, however, inhibited bacterial growth throughout 21 h of incubation. To confirm these results, serum from healthy volunteers was separated by ion exchange column chromatography and again by HPLC to purify the antimicrobial fraction. In the protein analysis with gradient polyacrylamide-SDS gel, apolipoprotein Al (apo Al), which is a major apolipoprotein of HDL, was detected in the antimicrobial fraction. Therefore, this fraction was loaded onto an immunoaffinity column coupled with the anti-apo Al monoclonal antibody (Mab). Unbound fraction had no antimicrobial activity, but anti-S. epidermidis activity was recovered from the bound fraction which consisted mainly of apo Al, All and apo C in protein composition. These results indicated that the antimicrobial activity was associated with the apo Al-containing lipoprotein particles (HDL). This property of HDL may directly affect bacterial growth and promote the self-defense mechanisms of normal and immunocompromised individuals.

Anti-Bacterial Agents↗
PubMed1993

Gene introduction into mouse blastocysts via "pricking".

It is a well-known phenomenon that cultured mammalian cells that have been pricked in the presence of foreign DNA can be transformed. This micromanipulation 'pricking' technique was applied to mouse blastocysts to determine whether uptake of exogenous DNA would occur in the embryos. The middle region of the inner cell mass (ICM) was pricked three times in each blastocyst in a medium containing a linearized plasmid DNA. When the 60 treated blastocysts were transferred to the uterine horns of pseudopregnant females, 30 developing fetuses (50%) at the mid-gestation stage were obtained. Twenty-two of the 30 fetuses (73%) had less than 1 copy of the foreign DNA per diploid cell, as revealed by polymerase chain reaction (PCR)-Southern analysis, a sensitive technique combined with Southern blot processing of the PCR products. The 8 other fetuses were negative for the foreign DNA. When blastocysts were pricked in the presence of vector DNA coupling E. coli beta-galactosidase (beta-gal) gene to a mouse metallothionein-I (MT-I) promoter and assessed for beta-gal activity histochemically after 1 and 5 days of culture in the presence of 1 microM CdCl2, at least 65% of the embryos exhibited beta-gal activity mainly in the ICM region. These results indicate that mouse blastocysts can be transfected with a relatively high efficiency after pricking, and that the introduced gene expression occurs. This approach provides a means of mapping the regulatory elements of genes that are active in the mouse blastocyst ICM, and may be useful in investigating the fate of the ICM cells in an intact blastocyst by labeling them via pricking technique.

Animals↗
PubMed1993

Effects of probucol and pravastatin on plasma lipids, activities of postheparin lipoprotein lipase, and lecithin cholesterol acyltransferase and apo A-I containing lipoproteins with and without apo A-II in patients with moderate hypercholesterolemia.

In this study, plasma HDL fractions were separated by ultracentrifugation and apo A-I containing lipoproteins (A-I Lp) were then isolated using anti-apo A-I immunoaffinity chromatography. The A-I Lp were further separated into two fractions with the use of anti-apo A-II immunoaffinity chromatography. One fraction, Lp A-I, contained apo A-I without apo A-II, while the other, Lp A-I/A-II, contained both apo A-I and apo A-II. These techniques were applied to investigate the changes in HDL apoprotein composition in hypercholesterolemic subjects treated with either probucol or pravastatin. Treatment with probucol (500 mg/day) or pravastatin (10 mg/day) reduced mean plasma total cholesterol concentrations by 24% (p < 0.01) and 16% (p < 0.05), respectively. Both drugs caused some reduction in lipoprotein lipase activity, but neither had any influence on the activity of hepatic triglyceride lipase or lecithin cholesterol acyltransferase. Their effects on HDL-cholesterol levels and apoprotein composition differed markedly. Probucol significantly decreased the HDL-cholesterol concentration, the plasma apo A-I/apo A-II ratio, and the number of large particles of diameter greater than 10.4 nm. When the ratios of Lp A-I and Lp A-I/A-II for the probucol-treated subjects were compared with those in the normolipidemic controls, and with the ratios before and after administration of probucol, a remarkable decrease in the level of Lp A-I was apparent. It is presumed that the decrease in HLD-cholesterol by prolonged probucol administration reflects the decrease of Lp A-I more than the decrease of Lp A-I/A-II.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoprotein A-I↗
PubMed1993

A simple and rapid method for cryopreservation of mouse 2-cell embryos by vitrification: Beneficial effect of sucrose and raffinose on their cryosurvival rate.

Survival of mouse 2-cell embryos was evaluated after exposure to 1.38, 2.75 or 5.5 M single cryoprotectants [dimethylsulphoxide (DMSO), acetamide (Ac) and propylene glycol (PG)], components frequently utilized as a vitrification solution, for 0.5, 1, 2 and 10 minutes at room temperature prior to vitrification. More than 80 % of the treated embryos developed to normal blastocysts in culture, after exposure to 1.38-2.75 M of each reagent for 0.5 minutes, although Ac tended to provide with have a deleterious effect on their survival. When the embryos were vitrified with solutions containing DP (2.75 M DMSO and 2.75 M PG) plus 0, 0.5 and 1.0 M Ac after a 0.5-minute exposure, their in vitro survival rates to the blastocysts were 44, 41 and 37%, respectively, showing no significant difference among them (x(2)=0.1-0.6, P>0.05). This indicates that the presence of Ac is not always needed for vitrifying mouse 2-cell embryos. Embryos, that had been vitrified with DP solution supplemented with 1.0 M sucrose (DPS) after a 0.5- minute exposure, exhibited significantly higher in vitro survival rate (82%) than those vitrified with DP (44%) (x(2)=23.4, P<0.001). Similar high survival rate (81%) was obtained when they were vitrified with DP plus 0.16 M raffinose (DPR) (x(2)=28.3, P<0.001). In vivo survival of embryos vitrified with DPS or DPR after a 0.5-minute exposure was both 49%, and there was no significant difference comparing to the unvitrified control group (60%). This method is rapid, efficient and reliable, and thus may be of practical use for cryopreserving mouse 2-cell embryos.

Journal Article↗
PubMed1993

Animal model of otitis media with effusion.

A rat model of otitis media with effusion (OME) was developed by intratympanic injection of E. coli endotoxin and section of the third branch of the trigeminal nerve (V3). The period of fluid retention induced by the endotoxin was prolonged for 5 days or longer, in cases when tubal function was impaired by cutting of V3. Three Eustachian tube function tests (patency test of inflation-deflation tests, forced response test and negative pressure test) were carried out before and after the endotoxin inoculation and V3 sectioning. At 4 days after these procedures, passive opening pressure (Po), closing pressure (Pc) and tubal resistance (R2) were significantly lowered. The negative pressure test showed impaired capacity of active opening. This model of Eustachian tube dysfunction is considered to reveal functional obstruction, a condition similar to that of clinical cases of OME. The study shows that both inflammation in the middle ear and tubal dysfunction, such as functional obstruction, are factors in the development and prolongation of OME.

Animals↗