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T Sankai

Publications and source records attributed to T Sankai.

At least 19 recordsLinked to original sources
PubMed2001

Behavioral compensations in a positional learning and memory task by aged monkeys.

The present experiment assessed learning and memory of a positional task by evaluating behavioral strategies as well as accuracy of a task in four young and four aged monkeys. They were tested in a delayed response (DR) task that has been widely used to study animal models of aging. The task consisted of two phases; an acquisition of the task and a positional memory test with five delay times (1-30 s). There was no clear difference between age groups in the number of trials needed for acquisition of the task. However, an analysis of behavior revealed differences in behavioral characteristics displayed during testing. The young monkeys showed various irrelevant behaviors during the execution of the task. In contrast, the aged monkeys consistently concentrated on the task exhibiting no behaviors irrelevant to the task. These results showed than the aged monkeys' performance was supported by a different behavioral strategy from the young monkeys. The results of the memory test were similar to those of the acquisition on the accuracy and the behavior. The aged monkeys depended on behavioral cues to preserve their positional memory, especially during the task. The present study suggests that cognitive impairments in aged monkeys can be compensated for by employing behavioral strategies.

Journal Article↗
PubMed2001

Short-term nonfrozen storage of mouse epididymal spermatozoa.

Six simple methods for short-term (up to 8 d), nonfrozen (5 to 20 degrees C) storage of mouse epididymides were compared with respect to the motility and fertility of spermatozoa. A high percentage of progressively motile spermatozoa was obtained from epididymis stored for 8 d at 5 degrees C in mineral oil (78.3%), covered with body fat (80.0%), or stored in the intact body of the euthanized donor animal (77.5%). Fertilized eggs (6.4% fertilization rate) were obtained by IVF using spermatozoa that had been stored in mineral oil at 5 degrees C for at least 8 d, and offspring were obtained from 77.5% of transferred eggs that were fertilized by spermatozoa stored for 2 d. These methods inhibited moisture loss from the preserved epididymal spermatozoa, thereby allowing spermatozoa to be stored for a few days without loss of either motility or fertility. These methods make possible such wide-ranging applications as the long-distance transport of epididymis spermatozoa. While in storage at 5 degrees C, the tail of each recovered spermatozoon was bent midway along the tail, possibly owing to damage to the plasma membranes and due to the spermatozoa's hardening in the phospholipid by exposure to the low temperature.

Animals↗
PubMed2001

Serum triglycerides and risk of coronary heart disease among Japanese men and women.

To examine the relation of triglycerides with coronary heart disease among populations with low mean total cholesterol, the authors conducted a 15.5-year prospective study ending in 1997 of 11,068 Japanese aged 40-69 years (4,452 men and 6,616 women with mean total cholesterol = 4.73 mmol/liter and 5.03 mmol/liter, respectively), initially free of coronary heart disease or stroke. There were 236 coronary heart disease events comprising 133 myocardial infarctions, 68 angina pectoris events, and 44 sudden cardiac deaths. The coronary heart disease incidence was greater in a dose-response manner across increasing quartiles of nonfasting triglycerides for both sexes. The multivariate relative risk of coronary heart disease adjusting for coronary risk factors and time since last meal associated with a 1-mmol/liter increase in triglycerides was 1.29 (95% confidence interval (CI): 1.09, 1.53; p = 0.004) for men and 1.42 (95% CI: 1.15, 1.75; p = 0.001) for women. The trend was similar for myocardial infarction, angina pectoris, and sudden cardiac death. The relation of triglycerides with coronary heart disease was not influenced materially by total cholesterol levels or, in a subsample analysis (51% of total sample), by high density lipoprotein cholesterol levels. Nonfasting serum triglycerides predict the incidence of coronary heart disease among Japanese men and women who possess low mean values of total cholesterol. Further adjustment for high density lipoprotein cholesterol suggests an independent role of triglycerides on the coronary heart disease risk.

Adult↗
PubMed2001

Immunolocalization of proliferating cell nuclear antigen (PCNA) in cynomolgus monkey (Macaca fascicularis) testes during postnatal development.

The age-related distribution of proliferating cell nuclear antigen (PCNA) in the testes of cynomolgus monkeys (Macaca fascicularis) during postnatal development was detected using light-microscopic immunohistochemistry. In neonatal testes, some PCNA-positive spermatogonia, Sertoli cells, peritubular cells, and Leydig cells were detected. In early infantile testes, only a few of these cell types were positive. In late infantile testes, the numbers of positive cells were greater than in the earlier developmental stages. In pubertal testes, the numbers of positive spermatogonia, spermatocytes, Sertoli cells, peritubular cells, and Leydig cells were considerably higher. In adult testes, a larger percentage of spermatogonia and spermatocytes was positive, and peritubular cells and Leydig cells were occasionally positive; secondary spermatocytes, spermatids, and Sertoli cells were not positive. We concluded that immunolocalization of PCNA can serve as a tool for studying proliferation status in developing testes of cynomolgus monkeys. A relatively low proliferative activity in early infantile testes and a remarkable increase of proliferative activity in pubertal testes correlate with the fluctuations of steroidogenic functions during postnatal development in cynomolgus monkeys.

Aging↗
PubMed2001

Cryopreservation-induced acrosomal vesiculation in live spermatozoa from cynomolgus monkeys (Macaca fascicularis).

BACKGROUND: Cryopreserved spermatozoa are known to undergo accelerated capacitation and require a shorter incubation time for fertilization. However, details of their acrosomal membranes following cryopreservation remain unclear. METHODS: Percoll density gradient centrifugation was used to remove dead spermatozoa; thus >90% live spermatozoa were recovered after cryopreservation, and acrosomal status was compared among non-incubated and incubated fresh and cryopreserved spermatozoa. RESULTS: Transmission election microscopy (TEM) using microwave methods and fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) staining revealed that 21.1 and 61.6% respectively of non-incubated, cryopreserved spermatozoa were intact, whereas 97.6% (TEM) or 91.9% (FITC-PSA) of non-incubated fresh spermatozoa were intact. TEM revealed that 28.8% of the cryopreserved spermatozoa were swollen, and probably included among those counted as intact by FITC-PSA staining. The non-incubated cryopreserved spermatozoa had fused plasma and outer acrosomal membranes, and 36.4% of them had vesiculation when observed by TEM. FITC-PSA staining indicated that 22% of the live spermatozoa were acrosome reacted. CONCLUSIONS: Acceleration of the acrosome reaction was evident by both TEM and FITC-PSA. Incubation of cryopreserved spermatozoa for 2 h accelerated vesiculation to a state similar to that of fresh spermatozoa that had been incubated for 8 h. These results reveal that in cryopreserved spermatozoa, the process of acrosome reaction begins before incubation.

Acrosome↗
PubMed2001

Activity of a sperm-borne oocyte-activating factor in spermatozoa and spermatogenic cells from cynomolgus monkeys and its localization after oocyte activation.

It is widely accepted that mature mammalian oocytes are induced to resume meiosis by a sperm-borne oocyte-activating factor(s) (sperm factor, SF) immediately after normal fertilization or intracytoplasmic sperm injection. The SF is most likely a soluble factor that is localized within the cytoplasm of mature spermatozoa, but the exact stage at which it appears during spermatogenesis and its localization after oocyte activation is not fully understood, except in the mouse. First, we injected mature spermatozoa and spermatogenic cells from cynomolgus monkeys into mouse oocytes to assess their oocyte-activating capacity. More than 90% of mouse oocytes were activated after injection of monkey spermatozoa. Round spermatids and primary spermatocytes (late pachytene to diplotene) also activated oocytes (93% and 79%, respectively). Injection of monkey spermatozoa and spermatids induces intracellular Ca(2+) oscillations in a pattern similar to that seen following normal fertilization. Most spermatocytes did not produce typical intracellular Ca(2+) oscillations. Second, we transferred pronuclei or cytoplasts from mouse oocytes that had been activated by monkey spermatozoa or spermatids into intact mature mouse oocytes by electrofusion in order to examine the localization of the SF after pronuclear formation. Some of the SF was localized within the pronuclei, but some stayed in the ooplasm. This study demonstrated that spermatogenic cells of cynomolgus monkeys acquire oocyte-activating capacity at much earlier stages than those of mice, and that the monkey SF has a pronucleus-directing nature, although to a lesser extent than the mouse SF.

Animals↗
PubMed2001

Prospective study of depressive symptoms and risk of stroke among japanese.

BACKGROUND AND PURPOSE: We sought to examine the relationship between depressive symptoms and the incidence of stroke among Japanese men and women. METHODS: A 10.3-year prospective study on the relationship between depressive symptoms and the incidence of stroke was conducted with 901 men and women aged 40 to 78 years in a rural Japanese community. Depressive symptoms were measured at baseline with the use of the Zung Self-Rating Depression Scale (SDS). The incidence of stroke was ascertained under systematic surveillance. RESULTS: During the 10-year follow-up, 69 strokes (39 ischemic strokes, 10 intracerebral hemorrhages, 10 subarachnoid hemorrhages, and 10 unclassified strokes) occurred. Age- and sex-adjusted prevalence of mild depression (SDS scores >/=40) at baseline was 25% among subjects with incident stroke and 12% among subjects without stroke (P<0.01). Persons with SDS scores in the high tertile had twice the age- and sex-adjusted relative risk of total stroke as those with scores in the low tertile. The excess risk was confined to ischemic stroke. After we adjusted for body mass index, systolic blood pressure level, serum total cholesterol level, cigarette smoking, current treatment with antihypertensive medication, and history of diabetes mellitus, these relative risks remained statistically significant for total stroke (1.9; 95% CI, 1.1 to 3.5) and ischemic stroke (2.7; 95% CI, 1.2 to 6.0). CONCLUSIONS: Depressive symptoms predict the risk of stroke, specifically ischemic stroke among Japanese.

Adult↗
PubMed2001

Short-term preservation of mouse oocytes at 5 degrees C.

The temporary preservation of oocytes without freezing would be useful for some experiments. ICR mouse oocytes were kept in a preservation medium under mineral oil for 1, 2, 3, 4 or 7 days at 5 degrees C, and 1 or 2 days at 37 degrees C. In vitro fertilization was attempted on oocytes rinsed with TYH medium after preservation. More than 70% of morphologically normal oocytes were recovered from each preservation group. Fertilization rates of oocytes preserved for 1, 2, 3, 4 or 7 days at 5 degrees C were 69.9, 66.5, 45.3, 26.7 and 8.8% respectively. Fertilization rates of oocytes preserved for 1 or 2 days at 37 degrees C were 9.6 and 1.6%, respectively. Preservation of oocytes at 5 degrees C has some capability as a method of short-term storage without freezing.

Animals↗
PubMed2001

[Trends in the incidence of cardiovascular diseases and risk factors among urban and rural Japanese males].

OBJECTIVES: To examine long-term trends in the incidence of coronary heart disease, stroke, and their risk factors among Japanese populations, we explored 32 years of surveillance data for male residents in urban and rural areas in Japan. METHODS: The surveyed populations were 40-79 year-old male residents in M community (population over 40 years old in 1995 was 11,121) of Y City in Osaka (urban area; Osaka) and I town (n = 3,571) in Akita prefecture (rural area; Akita). Incidence rates of coronary heart disease (myocardial infarction, angina pectoris), sudden cardiac death, percutaneous transluminal coronary angioplasty (PTCA) and stroke per 1,000 person-years were calculated for 1964-71, 1972-79, 1980-87 and 1988-95. Risk factors were evaluated by cross-sectional surveys conducted in the median years for each period. Dietary intake was examined by the 24-hour recall method in the latter three periods. RESULTS: Age-adjusted incidence of coronary heart disease per 1,000 men increased progressively from 0.27 in 1964-71 to 0.90 in 1988-95 (P = 0.222 for trend) among 40-59 year old residents in Osaka. Among their 60-79 year old counterparts, though the incidence was 2.62-3.11 and did not change over the periods studied, the combined rates for coronary heart disease and men who had a PTCA reached 3.79 in 1988-95. In contrast, the incidence of coronary heart disease among Akita residents did not change over time and stroke declined 70 percent between 1964-71 and 1988-95 (P < 0.001) in both 40-59 and 60-79 year age group: The decrease in cerebral infarction was less marked between 1980-87 and 1988-95 among 60-79 year old individuals. Significant increases in diastolic blood pressure, total serum cholesterol, body mass index, salt intake and total fat percent of total energy in Osaka, were associated with the elevation in the incidence of coronary heart disease. In Akita, blood pressure leveled off over the study period, but decreased less during the last decade whereas the prevalence of obesity increased. CONCLUSION: Trends in cardiovascular diseases and their risk factors differ among different geographical areas. The present long-term study, in particular, demonstrated an increase in the incidence of coronary heart disease among urban Japanese male residents in Osaka between the 1960s and the 1990s.

Adult↗
PubMed2000

Recent advances in the microinsemination of laboratory animals.

Microinsemination techniques were applied to laboratory animals, including mice, Mongolian gerbils, mastomys, guinea pigs and cynomolgus monkeys. After micro-insemination with spermatozoa or round spermatids, their oocytes were successfully fertilized and subsequently developed into 4-cells to blastocysts, depending on species. The efficiencies of microinsemination techniques for producing fertilized oocytes were comparable with, or superior to those of IVF in these species.

Animals↗
PubMed2000

Angiotensinogen T174M and M235T variants, sodium intake and hypertension among non-drinking, lean Japanese men and women.

OBJECTIVE: To examine the interaction of sodium intake with genetic variations of the angiotensinogen gene and hypertension. DESIGN: A community-based case-reference study. SETTING: Two rural Japanese communities. PARTICIPANTS: Non-overweight and non-drinking Japanese men and women: 229 hypertensives and 229 age-, sex- and community-matched normotensives aged 32 to 83 years. METHODS: Polymorphisms of the angiotensinogen gene detected by an allele-specific polymerase chain reaction. A priori hypothesis is individuals with 174M (threonine-to-methionine substitution) or 235T (methionine-to-threonine substitution) allelic variations may have an elevated risk of hypertension when they have a high sodium intake, estimated by 24-h urine collection and a dietary questionnaire. RESULTS: The genotypic frequency of the haplotype including both the 174M and 235T alleles was higher among hypertensives than among normotensives (23 versus 14%, P= 0.02). The frequency of the 174M allele was specifically higher among hypertensives than normotensives (12 versus 7%, P=0.01), and the odds ratio of hypertension associated with the 174M (versus 174T) allele was 1.8 [95% confidence interval (CI) 1.1-3.0, P=0.01]. The frequency of the 235T allele did not vary between the two groups (80 versus 82%, P= 0.40). The relationship between the 174M allele and hypertension was more evident among persons who had higher urinary sodium excretion (> = 166 mmol/day) than those with lower excretion (< 166 mmol/day): odds ratio 2.5 (95% CI, 1.2-5.2), P=0.01 versus 1.5 (95% CI, 0.7-3.1), P= 0.31; P for interaction = 0.04, and this trend was primarily observed for early-onset hypertension (< 55 years at onset). A similar but nonsignificant association was observed when stratified using present and past sodium intake scores derived from questionnaires. CONCLUSION: Angiotensinogen genotype may affect the development of early-onset hypertension among Japanese, particularly in those who have a high sodium intake.

Adult↗
PubMed2000

Comparison of the effects of two fixatives for immunolocalization of testosterone in the testes of the cynomolgus monkey, mouse and rat.

We compared the effect of two fixatives, Bouin's fixative and neutralized buffered 4% formaldehyde (10% formalin), for immunolocalization of testosterone in the testes of cynomolgus monkeys, mice and rats. In the samples fixed with Bouin's fixative, immunoreactive testosterone was detected as intense deposits in the cytoplasm of Leydig cells of monkeys and mice. Immunoreactive testosterone was detected not only in Leydig cells of rats but also moderately shown within tubules. Immunoreactive testosterone could not be detected in the testes of monkeys, mice or rats fixed with neutralized buffered formalin because of the poor morphology caused by the fixative. It is concluded that Bouin's fixative is a suitable fixative for immunolocalization of testosterone in the testes of cynomolgus monkeys, mice and rats.

Acetic Acid↗
PubMed2000

In vitro manipulation of nonhuman primate gametes for embryo production and embryo transfer.

Since nonhuman primates are closely related to humans and share many physical similarities, they are important for use in research areas such as human infectious diseases, reproduction, physiology, endocrinology, metabolism, neurology and longevity. To develop and maintain these animals, we must establish techniques for in vitro manipulation of spermatozoa and eggs. For a decade my research group has been conducting basic research to establish embryo manipulation techniques and to clarify the reproductive phenomena in nonhuman primates. This article summarizes the past research on in vitro manipulation of nonhuman primate gametes, from collection of reproductive cells and in vitro fertilization to the birth of offspring after embryo transfer, as well as the current status of these research areas. The studies summarized here will directly lead to the development of standard techniques for practical and comprehensive use in nonhuman primates.

Animals↗
PubMed2000

Validity and reliability of the Japanese version of the selected anger expression scale and age, sex, occupation and regional differences in anger expression among Japanese.

To examine the reliability and construct validity of the Japanese version of the Anger Expression Scale among four Japanese communities, and to examine distributions of anger expression scores according to sex, age, occupation, and community, we performed a cross-sectional study among 1,802 men and 3,229 women aged 20-70 in four geographic populations in 1995-97. We handed a self-administered questionnaire, which was selected from the Spielberger Anger Expression Scale, to the participants in the risk factor surveys and measured anger-in and anger-out as the anger expression scale. These scales had high internal consistency (Cronbach's alpha coefficient was 0.97-0.98 for anger-out and 0.77-0.86 for anger-in) and were of almost the same structure as the original. The Pearson correlation coefficients for the anger expression scale examined in 1995 and 1996 were 0.69 for anger-out and 0.57 for anger-in (both p < 0.001). The mean scores of both anger-out and anger-in were inversely associated with age. The mean anger-out score was higher for men than for women (p < 0.001), whereas the mean anger-in score did not vary significantly between the sexes. Furthermore, the mean scores of anger-out and anger-in varied among populations and occupational groups. The present study suggests that the Japanese version of the selected Anger Expression Scale is an acceptable scale for evaluating anger expression among Japanese.

Adult↗
PubMed2000

Prospective study on alcohol intake and risk of subarachnoid hemorrhage among Japanese men and women.

BACKGROUND: Few prospective data are available to evaluate potential risk factors of subarachnoid hemorrhage among the Japanese, although several prospective studies conducted in the United States and in Europe have shown a positive relationship between alcohol intake and the risk of subarachnoid hemorrhage. METHODS: A 9.4 year follow-up study was conducted on 12,372 men and women age 40 to 69 years who had no history of stroke, in six communities in Japan. The incident cases of subarachnoid hemorrhage were confirmed with computed tomography findings and/or clinical findings. Alcohol intake and other cerebrovascular risk factors were measured at the baseline examination. A Cox proportional hazard analysis was used to estimate the relative risks and 95% confidence intervals of the incidence of subarachnoid hemorrhage. RESULTS: During the follow-up assessment, 71 cases of subarachnoid hemorrhages occurred. For men, heavy drinking appeared to be an independent risk factor for subarachnoid hemorrhage; multivariate-adjusted relative risk was 4.3 (95% confidence interval [CI]: 1.1-16.8; p = 0.04). Among women, no excess risk was found for heavy drinking, probably due to the small number of heavy drinkers (n = 15). The combination of heavy drinking with smoking or hypertension increased the risk of subarachnoid hemorrhage substantially for men; the multivariate-adjusted relative risk was 6.0 (95% CI: 1.8-20.1;p = 0.004) for heavy drinking smokers and 13.0 (95% CI: 3.9-43.9; p < 0.001) for heavy drinking hypertensives. CONCLUSIONS: A reduction in alcohol intake, smoking cessation, and control of hypertension are important in preventing subarachnoid hemorrhage among Japanese men.

Adult↗
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↗