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Biomedical subjects

F Cho

Publications and source records attributed to F Cho.

At least 19 recordsLinked to original sources
PubMed1999

A two-step extraction method to measure fecal steroid hormones in female cynomolgus monkeys (Macaca fascicularis).

We developed a two-step extraction method for measuring fecal steroid concentrations. In the first step, distilled water was used to extract steroids from fecal samples. In the second step, a mixture of organic solvents (hexane and ether) was used to re-extract water extracts that had been transferred to a glass tube. A portion of the upper layer of the organic solvents was transferred to separate assay-tubes for measurement of estradiol (E2) or progesterone (P), and the organic solvents were evaporated in vacuo. After phosphate-buffered saline was added to each tube, commercially supplied radioimmunoassay (RIA) kits were used to determine the steroids. We demonstrated the advantages and reliability of this method by using it to assay the steroid hormone concentrations in fecal samples and serum samples collected on the same day from female cynomolgus monkeys who showed normal menstrual cycles and from monkeys who had induced hyperfunction of ovarian steroidgenesis. Different fecal samples from each monkey were used to determine the recovery rate of each steroid in water extraction from the fecal samples and the reproductivity of hormone concentrations in the fecal samples. The results demonstrate that this two-step method is simple and effective for measuring fecal steroids for monitoring the reproductive status of cynomolgus monkeys, without having to collect serum samples.

Animals↗
PubMed1999

Localization of immunoreactive testosterone and 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase in cynomolgus monkey (Macaca fascicularis) testes during postnatal development.

The age-related expression of testosterone and 3beta-HSD in the testes of cynomolgus monkeys was detected using light-microscopic immunocytochemistry. Intense deposits of immunoreactive testosterone were labeled in parts of Leydig cells in neonatal, late infantile, pubertal, and adult testes, and only a few Leydig cells in early infantile testes. The immunoreactive 3beta-HSD was labeled in parts of Leydig cells and in all Sertoli cells in neonatal, late infantile, pubertal, and adult testes, whereas only a few Leydig cells, but no Sertoli cells, were labeled in early infantile testes. The fluctuations of testosterone and 3beta-HSD expression in testes correlated well with those already observed plasma testosterone levels during postnatal development in cynomolgus monkeys.

3-Hydroxysteroid Dehydrogenases↗
PubMed1998

Comparison of two methods of assisted fertilization in cynomolgus monkeys (Macaca fascicularis): intracytoplasmic sperm injection and partial zona dissection followed by insemination.

Intracytoplasmic sperm injection (ICSI) and partial zona dissection followed by insemination (PZD-I) were used to establish a microinjection system in cynomolgus monkeys (Macaca fascicularis), which are potential models for human reproduction. Two experimental systems were studied, in which either hamster oocytes or cynomolgus monkey oocytes were used as the vehicle. When hamster oocytes were used, 66 out of 81 ICSI-treated oocytes (82%) showed sperm head swelling or pronucleus formation. Following PZD-I of hamster oocytes the rates of spermatozoa penetration (85/114; 75%) and fertilization (71/114; 62%) were relatively high. When cynomolgus monkey oocytes were used, 19 out of 31 (61%) were fertilized by ICSI with cynomolgus monkey spermatozoa and, subsequently, two embryos (7%) developed to the morula stage. In total, 94% (15/16) of the PZD-I treated oocytes were penetrated by spermatozoa and 63% (10/16) were fertilized. These results demonstrate that both micromanipulation techniques can be used in assisted fertilization with cynomolgus monkeys.

Animals↗
PubMed1998

Localization of testosterone and 3beta-hydroxysteroid dehydrogenase/delta5-delta4-isomerase in cynomolgus monkey (Macaca fascicularis) testes.

The enzyme 3beta-hydroxysteroid dehydrogenase/delta5-delta4-isomerase (3beta-HSD) is essential for the biosynthesis of all classes of steroid hormones, including androgens. We localized testosterone and 3beta-HSD by light microscopic immunocytochemistry in the testes of adult cynomolgus monkeys. Immunoreactive testosterone was located as intense deposits in the labeled cytoplasm of Leydig cells, and located weakly in the interstitial tissues, basement membranes, and the regions near tubular walls within tubules. Immunoreactive 3beta-HSD was located in the cytoplasm of all Sertoli cells and was especially intense in the parts near tubular walls and located weakly to intensely in the cytoplasm of some Leydig cells. This is the first immunocytochemical evidence that Sertoli cells of cynomolgus monkeys, as well as Leydig cells, are involved in biosynthesis of androgens.

Animals↗
PubMed1998

Effects of single and multiple injections of ketamine hydrochloride on serum hormone concentrations in male cynomolgus monkeys.

Using simulated short- and long-term effect studies, we evaluated the effect of ketamine anesthesia on serum cortisol, testosterone, and immunoreactive luteinizing hormone (ILH) and bioactive LH (BioLH) concentrations in adult male cynomolgus monkeys. Cortisol, testosterone, and ILH were measured by use of radioimmunoassay, and BioLH was measured by use of a radioreceptor assay method. For the acute effect, the first group (eight monkeys) was given four successive intramuscular injections of ketamine (10, 5, 5, and 5 mg/kg of body weight at 0, 30, 60, and 110 min respectively). Blood samples were taken at 0, 15, 30, 45, 60, and 120 min. For the long-term effect, the second group (10 monkeys) was given a single injection of ketamine (10 mg/kg) once a week for 4 consecutive weeks. Blood samples were taken 5 to 10 min after each injection, then were used to determine the variation in hormone concentrations among the monkeys (inter-individual variation) and within each monkey (intra-individual variation). There were no statistically significant differences in serum cortisol, testosterone, ILH, and BioLH values between the first blood sample (before the ketamine injection) and sequential blood samples in monkeys of the first group. Although intra-individual variation in the hormones (i.e., hormonal change within each monkey) was not statistically significant, inter-individual variation (among the monkeys) was significantly (0.00001 < P < 0.033) different in monkeys of the second group. These results indicate that an adequate number of animals must be used to minimize animal-to-animal variability. Our results confirm that ketamine is a suitable anesthetic agent to immobilize male cynomolgus monkeys in experimental studies (short- and long-term studies) aimed at elucidating hormonal changes.

Anesthetics, Dissociative↗
PubMed1997

In vitro fertilization and preimplantation embryo development of African green monkeys (Cercopithecus aethiops).

Ovaries of five adult female African green monkeys were stimulated by repeated administrations of equine chorionic gonadotrophin (eCG), followed by a single administration of human chorionic gonadotrophin (hCG). Oocytes were collected from enlarged follicles 28 h after hCG administration and incubated in vitro for 288 h. Oocytes that had extruded the first polar body were inseminated with spermatozoa that had been incubated for 4 to 6 h in medium with caffeine and dibutyryl cyclic AMP. Of these oocytes, 66% were fertilized and the incidence of polyspermy was 37%. Eighty-two percent of the fertilized eggs cleaved, with some developing into expanded blastocysts.

Animals↗
PubMed1997

In vitro fertilization of follicular oocytes by frozen-thawed spermatozoa in Japanese monkeys (Macaca fuscata).

We report the cryopreservation of epididymal spermatozoa and in vitro fertilization for Japanese monkeys (Macaca fuscata). Ovarian stimulation of seven monkeys was studied by the administration of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) during the nonbreeding season, after which oocytes were collected from ovarian follicles. The oocytes were subjected to in vitro fertilization by the frozen-thawed epididymal spermatozoa collected from a male monkey during the nonbreeding season. Before the experiment the epididymides and oocytes were transported about 500 km, during which the epididymides were kept in mineral oil to prevent drying and the oocytes were kept in a maturation medium. This technique of cryopreservation and in vitro fertilization has a wide applicability in nonhuman primate reproduction, including the treatment of infertility and the preservation of wild, nonhuman primates.

Animals↗
PubMed1997

Microscopic management of procedural errors.

This article provides the clinician with several methods of dealing with furcation and post perforation as well as separated instruments. The endodontist must first understand how to eliminate procedural accidents that can occur, then, accurately and predictably treat those teeth to which accidents have occurred. Techniques to repair furcation and post perforations and retrieval of fractured root canal instruments are presented. An in-depth description of each technique has been included. Lastly, clinicians must be cognizant of limitations in treating these difficult problems that will arise in dental practice. Active patient participation and communication must be maintained during the scope of treatment to provide patients with the highest quality of endodontic service possible. A challenging variety of problems present to even the most skilled dental practitioner over time. The ability to diagnose and treat these difficult conditions relies heavily on the ability to envision adequately the source of the problem. In the past, operating loupes and headlamps were the most effective option afforded to practitioners as a solution to magnification and illumination. Not only were these devices cumbersome to use, but also the dentist was limited to performing the entire procedure under one level of magnification. The advantages of using the microscope in the correction of procedural errors enhances the operator's ability to perform each step in a procedure with a heightened sense of knowledge. The practitioner is cognizant of the exact details of an iatrogenic development because he or she has visualized the area in great detail. The reconstruction of the tooth or removal of instruments can be carried out with confidence because the dentist has more control of the working environment than ever before. New restorative materials and instruments are available so deliberate precision can be implemented with the microscope's ability to illuminate and magnify the working field. In time, these improvements in technology and techniques will result in greater confidence and success in the prevention and treatment of procedural errors.

Communication↗
PubMed1996

Studies on the mechanism of early onset macular degeneration in cynomolgus (Macaca fascicularis) monkeys. I. Abnormal concentrations of two proteins in the retina.

Cynomolgus (Macaca fascicularis) monkeys from three families, which showed symptoms of early onset macular degeneration was studied. Two proteins, albumin and glyceraldehyde 3-phosphate dehydrogenase, were found to have markedly altered concentrations in whole retina of the monkeys with early onset macular degeneration, compared with normal controls. SDS-polyacrylamide gel patterns detected a 40-70% increase in the concentration of albumin and about 65% decrease in the concentration of glyceraldehyde 3-phosphate dehydrogenase in these affected retinas. There was however no significant difference in the relative concentrations of albumin in the plasma samples of affected and normal monkeys belonging to the three families studied and to an unrelated family. These initial findings suggest that degradative as well as antioxidant enzymes might be involved in the mechanisms leading to macular degeneration. In addition, the results also correlate with a possible role of these two proteins in H2O2 toxicity and appear to indicate that oxidative stress is significant in the etiology of early onset macular degeneration.

Albumins↗
PubMed1996

Studies on the mechanism of early onset macular degeneration in cynomolgus monkeys. II. Suppression of metallothionein synthesis in the retina in oxidative stress.

Initial investigations done in this laboratory detected increased albumin and decreased glyceraldehyde 3-phosphate dehydrogenase concentrations in the retina of an animal model manifesting early onset macular degeneration. Both glyceraldehyde 3-phosphate dehydrogenase and albumin are markers of oxidative stress in cells. In this study, we used the same animal model to study further biochemical and physiological processes which may be involved in the pathogenesis of early onset macular degeneration in monkeys. We detected 60% lower catalase and glutathione peroxidase activities in the affected retinas suggesting lower antioxidant activities and oxidative stress. One of the consequences of oxidative stress is the production of metallothionein, a low molecular weight protein also induced by high concentrations of heavy metals such as zinc. Metallothionein was detected by RT-PCR in these monkey retinas. However initial quantitative PCR studies on this protein showed that the synthesis of metallothionein in affected retinas appears to be less than in normal controls. The affected retinas also showed a fourfold lower zinc concentration compared with the normal controls. No significant difference, however, could be detected in the zinc concentrations in plasma samples. Since induction of metallothionein synthesis is mediated by transcription factors which require heavy metals such as zinc for binding to specific sites in the DNA, the lowered zinc concentration may, thus, correlate with the lowered metallothionein expression. And since metallothionein is suggested to function as a free radical scavenger, the lowered metallothionein synthesis may consequently contribute to increased peroxidation reactions in the affected retinas. It appears therefore, that oxidative stress and the decreased metallothionein synthesis may be involved in the pathogenesis of early onset macular degeneration in this animal model.

Amino Acid Sequence↗
PubMed1996

Changes in bone mineral density of lumbar vertebrae after parturition in African green monkeys (Cercopithecus aethiops).

We examined the effect of lactation on the maternal bone components in laboratory-bred African green monkeys. Bone mineral density (BMD) with bone mineral content (BMC), bone area and mean width of lumbar vertebrae (L3-L5) were measured by dual-energy X-ray absorptiometry (DXA). Measurements were conducted at two-week intervals from parturition up to 40 weeks after parturition. The BMC and BMD values gradually decreased during the lactation period and then gradually increased after weaning, but the BMC and BMD of the maternal lumbar vertebrae did not recover completely to the values at parturition even at 40 weeks after parturition.

Absorptiometry, Photon↗
PubMed1994

Cryopreservation of spermatozoa from cynomolgus monkeys (Macaca fascicularis).

Fertilization of eggs from cynomolgus monkeys (Macaca fascicularis) was achieved in vitro using frozen-thawed spermatozoa. The best sperm survival rate was obtained after freezing spermatozoa in a semen-diluting medium (TTE: Tes, Tris, egg yolk base) containing 5% glycerol with 30 min equilibrium time. Although frozen-thawed spermatozoa could fertilize eggs in vitro and some of the fertilized eggs developed into blastocysts or hatched blastocysts, a sperm fertility assay using salt-stored eggs indicated that frozen-thawed spermatozoa had a shorter lifespan in capacitation medium than did fresh, unfrozen spermatozoa. This may be attributable to damage to their plasma membranes.

Animals↗
PubMed1994

[A feeding experiment on laboratory-bred male cynomolgus monkeys. I. Morphometrical study].

Effects of restricted feeding on the growth of laboratory-bred male cynomolgus monkeys (Macaca fascicularis) aged between one year and four years were studied morphometrically. A series of 11 variables representing physical elements were measured. Before 2.5 years of age, the amount of commercial diet (Type AS, 382kcal/100g and 28.1% of crude protein, Oriental Yeast Co. Ltd.) per day was restricted to 50g (group A), 30g (group B) or 20g (group C) and increased to 100g (group A), 50g (group B) or 40g (group C) respectively at 2.5 years old. Throughout the experimental period ca 100g of apples and oranges per day were provided. Significant differences in body weight between group A and C were detected excepting the early period of the experiment. Although the slight suppression in weight gain was observed in group B during the second trimester of the experiment, body weight increased gradually after increasing the amount of food and no significant difference from A was observed at four years of age. The minimum requirement of diets is judged to be 30g/day before two years old and 50g/day over two years old in the laboratory-bred male cynomolgus monkey. Moreover, the suppressive effects of restricted feeding were most significant on the growth of the limbs and, secondarily, on the growth of the trunk. Practically no effect on the growth of the head was observed.

Animal Feed↗
PubMed1994

[Feeding experiment on laboratory-bred male cynomolgus monkeys. II. Hematological and serum biochemical studies].

The effects of restricted feeding on hematological and serum biochemical values were studied in laboratory-bred male cynomolgus monkeys (Macaca fascicularis) aged between one year and four years. In animals younger than 2.5 years old, the amount of commercial diet (Type AS, Oriental Yeast Co. Ltd.) given per day was restricted to 50 g (group A), 30 g (group B) or 20 g (group C) and increased to 100 g (group A), 50 g (group B) or 40 g (group C) at 2.5 years old. Throughout the experimental period, about 100 g per day of apples and oranges were fed to the animals. Differences in red blood cell counts, hematocrit values and hemoglobin concentrations between groups A and C were detected in the middle period of the experiment. The function of hematogenesis may be suppressed by restricted feeding. A significant increase in serum triglyceride concentration in group C and slight increase in group B were observed during the second trimester of the experiment. A decrease in serum alkaline phosphatase activities in group C during the same period suggests that restricted feeding has a suppressive effect on bone growth. The results obtained by hematological and serum biochemical observations in this study are in good agreement with the previous somatometric study [10].

Alkaline Phosphatase↗
PubMed1994

[Age-related changes in bone mineral density, mean width and area of the lumbar vertebrae in male African green monkeys (Cercopithecus aethiops)].

We were able to measure bone mineral density (BMD), mean bone width and the area of the lumbar vertebrae in male African green monkeys with a dual-energy X-ray absorptiometry (DPX-alpha, Lunar, USA). For analysis of spinal bone mass, mean width and area of the bone, we scanned lumbar vertebrae L3-L5 using a pediatric analysis program. We used restraining bed made of formed polystyrol to support the animal in a supine position. The precision of the measuring technique was calculated by averaging the coefficients of variance of the 5 scans obtained in 5 animals aged from 5 to 7 years. The precision values for BMD, bone width and area were 1.9%, 0.9% and 2.6%, respectively. Furthermore, age-related changes in bone measurements were demonstrated using laboratory-bred males (n = 45) and, additionally, wild-originated males (n = 7, estimated ages over 15 years old). The values of B M D, bone width and area at 6 months old were about 0.3 g/cm2, 1.2cm and 4.5 cm2 respectively. These values increased with aging to about 0.7 g/cm2, 1.5 cm and 11cm2 at 5 years old, respectively, and were judged to reach plateau. However, animals over 10 years old and wild-originated animals which had been kept over 10 years in our breeding colony showed rather smaller BMD and area values than the animals aged 5 to 10 years. The animals aged between 5 and 10 years seemed to have retained a peak bone mass in this primate species.

Absorptiometry, Photon↗
PubMed1994

[Measuring bone mineral content and soft tissue mass in living the cynomolgus monkey].

Bone mineral content and soft tissue (lean and fat) mass in living female cynomolgus monkeys were successfully measured with a dual-energy X-ray absorptiometry (DEXA; DPX-alpha, LUNARE, USA). Measurements were performed using a restraining bed made of forming polystyrol with 5cm thickness to support the animal in a supine position. Accuracy of measurements was checked by using a dummy consisted by various combinations of lean, lard and ribs. The results confirmed that this system is able to measure each constituent exactly. The percentage of fat in the soft tissue is seemed to be better index of obesity in this primate species when compared with other obesity markers such as body weight and morphometry.

Absorptiometry, Photon↗