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Biomedical subjects

C Polge

Publications and source records attributed to C Polge.

At least 19 recordsLinked to original sources
PubMed1998

Mental health expectancy--the European perspective: a synopsis of results presented at the Conference of the European Network for the Calculation of Health Expectancies (Euro-REVES). Medical Research Council Cognitive Function and Ageing Study Group.

The increase in life expectancy observed over the last decade has particular relevance for mental health conditions of old age, such as dementia. Although mental disorders have been estimated to be responsible for 60% of all disabilities, until recently population health indicators such as health expectancies have concentrated on calculating disability-free life expectancy based on physical functioning. In 1994, a European Network for the Calculation of Health Expectancies (Euro-REVES) was established, one of its aims being the development and promotion of mental health expectancies. Such indicators may have an important role in monitoring future changes in the mental health of populations and predicting service needs. This article summarizes the proceedings and recommendations of the first European Conference on Mental Health Expectancy.

Aged↗
PubMed1997

Impact of anesthesia on the cognitive functioning of the elderly.

Exposure to general anesthesia has been suggested as a possible cause of long-term cognitive impairment in elderly subjects. The present study reviews the literature in this field in order to describe postoperative cognitive impairment in elderly populations, to determine to what extent this may be attributed to anesthetic agents, and to consider evidence of a causal relationship between anesthesia and onset of senile dementia. A systematic literature search was conducted using five bibliographic databases (PASCAL, Medline, Excerpta Medica, Psychological Abstracts, and Science Citation Index). Significant cognitive dysfunction was found to be common in elderly persons 1 to 3 days after surgery, but reports of longer-term impairment are inconsistent due to the heterogeneity of the procedures used and populations targeted in such studies. Incidence rates vary widely according to type of surgery, suggesting that factors other than anesthesia explain a significant proportion of the observed variance. Anesthesia appears to be associated with longerterm cognitive disorder and the acceleration of senile dementia, but only in a small number of cases, suggesting the existence of other interacting etiological factors.

Aged↗
PubMed1989

Survival of mouse embryos after being frozen in glycerol-sucrose mixture.

Random bred female albino mice (6-8 weeks old) were used as a source of embryos. 8- to 16 cell embryos were dehydrated in glycerol-sucrose mixture in 0.25 ml straws at room temperature. Straws were cooled at the rate of 5 degrees C/min to -7 degrees C. Seeding was induced by touching the out side of the straw at -7 degrees C. Straws were further cooled at 0.5 degree C/min down to -35 degrees C and then plunged into liquid N2. Thawing of straws was done by direct transfer into water at 35 degrees C. Frozen-thawed embryos were cultured in a CO2 incubator maintained at 39 degrees C. Out 190 embryos (8-16 cell) initially frozen, 169 (88.94%) were recovered on thawing. 158 (93.5%) out of 169 were apparently normal and used for culture. 75 (47.46%) developed to morulae/early blastocysts and 72 (45.56%) to expanded blastocysts on 24 and 48 hr culture respectively. In conclusion, the incorporation of sucrose in the freezing medium at a concentration of 0.25 M has led us to propose a freezing, thawing and transfer method without dilution of glycerol. The technique being quite simple is worth trying in farm animals where importance of this technique in non-surgical transfer of frozen-thawed embryos will be a boon.

Animals↗
PubMed1989

A protocol used for splitting mouse embryos into two halves.

8-16 cell embryos and early blastocysts were obtained from the oviducts and anterior portion of uterine horns of albino mice at 70 and 90 hr after LH injection respectively. Splitting of embryos was done by using two microtools attached to a micromanipulator unit (Research Instruments Ltd, UK). After bisection, each pair of the half embryos is transferred to a dish containing 2 ml of T-6 medium and cultured in CO2 incubator (at 39 degrees C, 95% RH and 5% CO2 in air mixture). Splitting of blastocysts as compared to 8-16 cell embryos was found difficult (35.48% vs 52.44%, respectively). 38.88% of bisected 8-16 cell embryos and 11.36% of bisected blastocysts developed on 48 hr culture. Information on splitting mouse embryos and their subsequent development in culture are significant in view of using the technique for commercial application and for research in developmental biology of animal embryos.

Animals↗
PubMed1989

Cryopreservation of mouse embryos at -196 degrees C by vitrification.

Embryos (8-16 cell) were obtained from random bred albino mice (6-8 weeks old) that were induced to superovulate by injections of 5 I.U. PMSG and 5 I.U. hCG given 48 hr apart. Embryos were exposed to intracellular cryoprotecting medium (glycerol 10%, 1-2 propanediol 20% in PBS) for 10 min and then transferred to extracellular vitrification medium (25% glycerol, 25% 1-2 propanediol in PBS). Vitrification medium containing embryos, and diluent (1 M sucrose) were loaded in a straw and immediately plunged into liquid N2. After thawing at 20 degrees C, the contents of the straw were mixed by shaking (1 step dilution) and emptied in a petri dish. After 3 washings in culture medium the embryos were kept in CO2 incubator for further development. In 3-step dilution procedure the dilution of cryoprotectants was done in 0.5 and 0.25 M sucrose before culture. Embryos in 3-step dilution of cryoprotectants exhibited high survival as compared to 1-step dilution (20.23% vs 6.55%).

Animals↗
PubMed1985

How does embryo manipulation fit into present and future pig reproduction?

Available techniques for the collection and direct transplantation of pig embryos are simple and efficient and could be used for the expansion of new lines, for increasing selection pressure in nucleus herds and for extracting healthy stock from a diseased source. However, the reduced viability of pig embryos during culture in vitro and the inability as yet to preserve them by deep-freezing impose limits to the use of embryo transplantation for the export or import of potential breeding stock. The efficiency of breeding schemes could be improved by the sexing of embryos and the possibility of producing genetically identical twins or quadruplets by micromanipulation of embryos should improve the efficiency of animal experimentation. Chimaerism may be used to rescue embryos of a non-viable genotype such as parthenotes or those derived by hybridization, but the greatest revolution in pig breeding may be brought about by the introduction of foreign cloned genes into eggs and the production of transgenic animals. Eggs at an appropriate stage for microinjection may be provided in the future by techniques for the maturation and fertilization of oocytes in vitro. Animal breeders should be aware of the potential impact of techniques for the manipulation of eggs and embryos on future developments in animal production.

Animals↗
PubMed1984

Effect of warming rate on mouse embryos frozen and thawed in glycerol.

Mouse embryos (8-cell) fully equilibrated in 1.5 M-glycerol were cooled slowly (0.5 degrees C/min) to temperatures between - 7.5 and - 80 degrees C before rapid cooling and storage in liquid nitrogen (-196 degrees C). Some embryos survived rapid warming (approximately 500 degrees C/min) irrespective of the temperature at which slow cooling was terminated. However, the highest levels of survival of rapidly warmed embryos were observed when slow cooling was terminated between -25 and -80 degrees C (74-86%). In contrast, high survival (75-86%) was obtained after slow warming (approximately 2 degrees C/min) only when slow cooling was continued to -55 degrees C or below before transfer into liquid N2. Injury to embryos cooled slowly to -30 degrees C and then rapidly to -196 degrees C occurred only when slow warming (approximately 2 degrees C/min) was continued to -60 degrees C or above. Parallel cryomicroscopical observations indicated that embryos became dehydrated during slow cooling to -30 degrees C and did not freeze intracellularly during subsequent rapid cooling (approximately 250 degrees C/min) to -150 degrees C. During slow warming (2 degrees C/min), however, intracellular ice appeared at a temperature between -70 and -65 degrees C and melted when warming was continued to -30 degrees C. Intracellular freezing was not observed during rapid warming (250 degrees C/min) or during slow warming when slow cooling had been continued to -65 degrees C. These results indicate that glycerol provides superior or equal protection when compared to dimethyl sulphoxide against the deleterious effects of freezing and thawing.

Animals↗
PubMed1984

Cryoprotection of day-4 mouse embryos by methanol.

Methanol was examined as a cryoprotective additive that permits the direct transfer of frozen--thawed Day-4 mouse embryos to foster mothers without dilution of the cryoprotectant. Methanol permeated the embryos rapidly, was not toxic and exerted a cryoprotective action. The highest level of survival (50%) of embryos in vitro was observed after equilibration in Medium PB1 containing 3.0 M-methanol, slow cooling (0.5 degrees C/min) to a temperature between -30 and -40 degrees C, rapid cooling (800 degrees C/min) and storage in liquid nitrogen (-196 degrees C), rapid warming (800 degrees C/min), and rapid dilution. A high rate of development in vivo to late-stage fetuses (up to 81%) was observed when cryopreserved embryos were transferred to pseudopregnant recipients immediately after thawing.

Animals↗
PubMed1984

Pattern of medium proteins radiolabelled after culture of Day 13 to 16 pig conceptus tissue with [3H]leucine and absence of chorionic gonadotrophin-like activity.

Day 13-16 pig conceptus tissue was cultured for 24 h in medium containing [3H]leucine. The patterns of radioactively labelled proteins that were released into the medium during culture were analysed by SDS-polyacrylamide gel electrophoresis and fluorography. Day-13 conceptuses released two major radiolabelled proteins of Mr 23 000 and 26 000 and Day 14-16 conceptuses released these as well as proteins of Mr 14 000, 19 000, 44 000, 50 000 and 88 000. Various immunological and biological tests for a human chorionic gonadotrophin-like activity were performed on tissue extracts and on culture medium, but there was no evidence for its presence in the pig conceptus at Day 13-16 of gestation.

Animals↗
PubMed1982

Oestradiol administration raises luteal LH receptor levels in intact and hysterectomized pigs.

Occupied and unoccupied LH receptors in corpora lutea, and LH and progesterone concentrations in circulating plasma, were measured in non-pregnant gilts that had been treated with oestradiol-17 beta benzoate to prolong luteal function. Oestradiol benzoate (5 mg, administered on Day 12 after oestrus) delayed luteal regression and the decline in LH receptor levels at luteolysis and raised unoccupied receptor levels from 11.8 +/- 1.14 fmol/mg protein on Days 10--15 after oestrus to 31.8 +/- 3.26 fmol/mg protein on Days 15--21. There was no simultaneous rise in occupied receptor levels and occupancy decreased from 29.8 +/- 3.01 to 11.5 +/- 1.26%. Basal plasma LH concentrations were unchanged by oestradiol, but mean corpus luteum weight and plasma progesterone concentrations were slightly reduced. Oestradiol benzoate on Day 12 caused a similar increase in unoccupied receptor levels in gilts hysterectomized on Days 6--9 after oestrus, from 17.0 +/- 5.83 to 34.5 +/- 6.00 fmol/mg protein, determined on Days 15--18. Plasma concentrations of LH and progesterone were unchanged by oestradiol. Unoccupied receptor levels in corpora lutea and plasma LH and progesterone were unaltered by hysterectomy in untreated gilts. Occupied receptor levels were not influenced by hysterectomy or oestradiol. It is concluded that oestradiol-17 beta raises luteal LH receptor levels by a mechanism independent of the uterus.

Animals↗
PubMed1981

Attempts to produce monozygotic quadruplets in cattle by blastomere separation.

The blastomeres of eight-cell cow embryos were separated by micromanipulation into four pairs, inserted in foreign zonae pellucidae, embedded in agar and cultured for approximately four days in ligated sheep oviducts. Of 44 "quarter" embryos (11 monozygotic groups) transferred to sheep, 91 per cent had continued to develop at a normal rate and 77 per cent had formed small blastocysts with a single inner cell mass. Twenty-six blastocysts freed from the agar were transferred to heifers, each heifer receiving two monozygotic embryos, one to the tip of each uterine horn. Nine recipients were diagnosed pregnant by rectal palpation on day 50, six carrying twins. Thus 15 of the embryos had continued to develop including two sets of monozygotic quadruplets and one set of monozygotic triplets. Eight fetuses developed to full term, one set of monozygotic triplets, two sets of monozygotic twins (one set born dead) and one single.

Animals↗
PubMed1980

Effect of follicular steroids on the maturation and fertilization of mammalian oocytes.

Pronuclear development was used to measure the effects on ovine oocytes of altering follicular steroidogenesis during maturation in vitro. Follicular steroid secretion was altered using enzyme inhibitors and exogenous steroid supplementation. Abnormalities induced during maturation were measured 24 h after tranfer of oocytes to the oviducts of inseminated hosts. The presence throughout maturation of aminoglutethimide, an inhibitor of the conversion of cholesterol to pregnenolone, reduced steroid secretion to 7% of that in controls and decreased from 77% to 33% the number of normal oocytes. Abnormalities were substantially reduced by the addition of aminoglutethimide during the final 8 h of maturation only. The inhibition of 17 alpha-hydroxylase enzymes with SU10603 reduced oestrogen and testosterone secretion to about 10% of control levels but had no effect on progestin secretion. Only 13% of oocytes matured in the continual presence of SU10603 underwent normal fertilization. The number of oocytes undergoing normal fertilization was increased to about 50% by (i) delaying the addition of SU10603 until the last 8 h of the maturation period or (ii) adding exogenous steroids to follicles cultured with inhibitor from explantation. It is concluded that oocytes require a specific intra-follicular steroid environment for the completion of the full maturation process. Alterations to the steroid profile during maturation induce changes in the oocyte which are expressed as gross abnormalities at fertilization.

Aminoglutethimide↗