Gene mapping of mouse IL-4 receptor: the loci of interleukin 4 (IL-4) receptor gene and lymphocyte function associated antigen 1 (LFA-1) gene are closely linked on chromosome 7.
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Animals↗
Biomedical subjects
E Palmer
Publications and source records attributed to E Palmer.
Identification of a mouse T-cell antigen receptor alpha-chain polymorphism by a V alpha 3.2 chain-specific monoclonal antibody.
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Animals↗
Mls--a retrovirus exploits the immune system.
The identity of minor lymphocytes stimulating (Mls) antigens, endogenous superantigens that can activate, or induce the deletion of, large portions of the T-cell repertoire, has recently been revealed: they are encoded by mouse mammary tumor viruses (MMTV) that have integrated into the germ line as DNA proviruses. As Hans Acha-Orbea and Ed Palmer point out, Mls-mediated modulation may be only the tip of the retrovirus iceberg; already murine leukemia virus (MuLV), with similar superantigen properties, has been discovered.
Amino Acid Sequence↗
Infectious origins of superantigens.
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Journal Article↗
Effect of aspiration of the preovulatory follicle on luteinization, corpus luteum function, and peripheral plasma gonadotropin concentrations in the mare.
Follicular fluid from small- to medium-sized follicles has been shown to have an inhibiting effect on luteinization of granulosa cells in vitro. This study was conducted to investigate the effect of in vivo removal of follicular fluid on luteinization, peripheral gonadotropin concentrations, and ovulation of secondary follicles in the mare. Follicular fluid was aspirated from the preovulatory follicles of mares when the diameter of the follicle was 30-34 mm (Group A), 35-39 mm (Group B), or 40-44 mm (Group C). Mares in Group D served as controls and the preovulatory follicle was not aspirated. Mares in Group A had a significantly earlier rise in peripheral progesterone concentrations than did controls. There was no difference in duration of progesterone secretion or peak progesterone production between groups. LH and FSH values were significantly higher for mares in Groups A and B than for control mares. Mares in Group A tended to have a higher incidence of secondary ovulations than did mares in other groups. These data support the in vitro findings that follicular fluid from small- to medium-sized follicles may contain a luteinization inhibitor, and indicate that presence of follicular fluid during the final days of follicular maturation is not essential for development of a normal CL.
Animals↗
The response of guinea pig airway epithelial cells and alveolar macrophages to environmental stress.
Cells lining the respiratory tract form an interface between the organism and the external environment and are repeatedly exposed to physical, chemical, and metabolic stresses. We examined the response of cultured guinea pig tracheal epithelial cells and alveolar macrophages to various forms of stress, including clinically and environmentally relevant metabolic stresses such as ozone and acid exposure. Classic stress treatments such as heat shock and sodium arsenite treatment induced the synthesis of 28, 32, 72, 73, 90, and 110 kD stress proteins similar to those observed in other cell types. In contrast, no significant changes in the pattern of protein synthesis were detected after exposure to ambient concentrations of ozone, although ozone exposure caused significant cytotoxicity to both cell types. Another potent oxidant, hydrogen peroxide, similarly did not induce appreciable stress protein synthesis. However, surface acidification of tracheal epithelial cells and alveolar macrophages caused the induction of 72 and 78 kD stress proteins. While stress proteins may play a role in the response of respiratory cells to certain injuries such as hyperthermia and surface acidification, they may not be important in the defense against ozone or other forms of oxidative injury.
Animals↗
Use of concanavalin A for coating the membranes of stallion spermatozoa.
Semen from three ejaculates from each of 4 stallions was frozen in liquid nitrogen. Morphology was evaluated by coating the spermatozoa with fluorescein-labelled Concanavalin A (FITC-ConA2) and motility was measured by computer-assisted image analysis. Coating was performed at each step of the freezing procedure (dilution, cooling, addition of glycerol and freeze-thawing) and observations were made after each step, to evaluate changes, or after subsequent steps, to determine protection provided by the coating method. All the parameters showed progressive changes during the freezing procedure. Mean track speed of the spermatozoa, the proportions of normal and motile spermatozoa and lateral head displacement all decreased, whereas the proportions of spermatozoa exhibiting non-fluorescence in the equatorial segment and wrinkled acrosome membranes increased. The results demonstrated that coating stallion spermatozoa with ConA2 provides some degree of protection for acrosome membranes and it helps to preserve motility after freezing and subsequent thawing.
Animals↗
Effect of oral melatonin on the date of the first ovulation after ovarian inactivity in mares under artificial photoperiod.
Two experiments tested the hypothesis that exogenous melatonin (12 mg) given 4 h before dusk (evening melatonin), or near dawn (morning melatonin), would mimic a prolongation of the night and suppress stimulation of the ovaries induced by long days. Experiment 1 consisted of a non-stimulated control group, a control group stimulated by 14.5 h of light, a treated group stimulated with 14.5 h of light plus evening melatonin, a control group given 17.5 h of light and a treatment group given 17.5 h of light plus morning melatonin. The mean (+/- s.e.m.) intervals from the start of treatment to the first ovulation were 135 +/- 26, 68 +/- 4, 147 +/- 11, 94 +/- 6 and 107 +/- 13 days, respectively. Experiment 2 consisted of 3 groups exposed to 14.5 h of light, a control group and a morning and an evening melatonin group. The mean (+/- s.e.m.) intervals from treatment to first ovulation were 53 +/- 12, 62 +/- 8 and 101 +/- 5 days, respectively. Thus, evening melatonin suppressed the stimulatory effect of the applied light, but morning melatonin did not (P greater than 0.05). In non-treated mares, peripheral blood melatonin levels were higher at night than during the day. In the treated mares, very high plasma melatonin concentrations occurred 10-20 min after treatment and levels began to fall again immediately after this peak was reached. This decline was steeper after morning than the evening treatments. Conversely, the endogenous night-time plasma melatonin concentrations before the morning treatment were lower than the night-time levels measured in the treated animals. Two hypotheses are proposed: (a) exogenous treatment with melatonin in the morning is perceived as dusk and is followed by only approximately 5 h of high melatonin concentrations in the blood and (b) in the morning the mare is sensitive to light regardless of the presence of high levels of melatonin in her blood.
Administration, Oral↗
Ovarian response in mares to prolonged treatment with exogenous equine pituitary gonadotrophins.
Twelve anoestrous mares were treated with an intravaginal sponge containing 0.5 g allyl trembolone (Regumate; Roussel UCLAF, Paris) and 50 mg oestradiol benzoate for 7 days, followed by daily intramuscular (i.m.) injections of 25 mg crude equine pituitary extract (CEG), with (n = 6) or without (n = 6) 0.25 mg porcine growth hormone (pGH). No difference in ovarian response to this superovulation treatment was observed between the 2 groups (2.2 +/- 0.4 vs 2.3 +/- 0.4 ovulations per mare, respectively). CEG treatment was then combined with allyl trembolone (40 mg per os per day) and prolonged in the 12 mares, with (n = 6) or without (n = 6) a 7-day interruption of CEG treatment 7 days after the mares first ovulated. Ovarian responses showed that an interruption in gonadotrophin treatment was not necessary to allow the occurrence of a new follicular wave, but the interruption did seem to generate the growth of a more synchronous cohort of follicles. Ovulation rate in the second wave was higher than in the first although there was no effect of treatment interruption on ovulation rate in the second wave, which occurred during progestagen treatment and gave rise to persistent corpora lutea (36.5 +/- 5.9 days). The 6 mares that did not experience an interruption in treatment continued to receive daily CEG injections and oral progestagen. Two periods (Days 0-47 and Days 48-94) were compared for analysis of follicular growth.(ABSTRACT TRUNCATED AT 250 WORDS)
Anestrus↗
In vitro fertilization in the horse. A retrospective study.
Since the first successful collection of oocytes by non-surgical puncture, there have been numerous attempts to fertilize them but few segmented embryos have resulted. The latest attempts at follicular puncture (Palmer et al., 1987) provided 159 oocytes. Oocytes found broken (18%) were probably already broken, or at least fragile, before puncture. The 41 oocytes were fertilized only with semen treated with Ionophore A23187. Following ionophore treatment of semen, 16 ova segmented (of 113 inseminated oocytes) indicating fertilization, and another 7 showed signs of fertilization but not segmentation. Our basic protocol, when applied to 60 oocytes, yielded 11 (18%) embryos and 5 (8%) that were fertilized without segmentation. Modifications to the protocol produced no improvement in the results. Eight embryos fertilized in vitro were transferred into the ampulla of 8 recipient mares. One pregnancy resulted and foaling occurred June 14, 1990. This is the first equine pregnancy to continue to full term following in vitro fertilization.
Animals↗
Maturation of oocytes from normal and atretic equine ovarian follicles as affected by steroid concentrations.
The ovaries of 23 mares were collected at slaughter during April-June and follicles (4-40 mm in diameter) were dissected and punctured to obtain oocytes for culture. The follicles were grouped according to histology: (a) normal, (b) showing primary and (c) secondary atresia. Antral fluid was analyzed for steroid content; oestradiol and testosterone (but not progesterone or androstenediol) were closely correlated with follicle size and histological state. Oocytes were cultured early after slaughter in Medium 199 (Difco OSI, France) or Medium B2, the highest percentage of oocytes reaching Metaphase 2 (53%) occurred after 36-38 h in culture. Among the 52 oocytes cultured and inseminated 1 case was confirmed with a 4-blastomere-like structure, 10 cases had structures resembling pronuclei, 9 oocytes were in Metaphase 1, 14 were in Metaphase 2 and 18 were degenerated.
Androstenedione↗
Establishment of equine oviduct cell monolayers for co-culture with early equine embryos.
A culture for equine oviduct epithelial cells is described. Primary cultures reached confluence in 5-8 days, forming a monolayer of polygonal cells and remaining morphologically intact for about 20 days. Subcultures were obtained by collecting cells detached spontaneously from the monolayers, and confluence was reached again after 5-7 days. Cells frozen before primary culture were confluent 10-15 days after thawing. Dishes containing confluent cells also were frozen, and some cohesive monolayers formed after thawing. Equine embryos, collected 2 days after ovulation, were cultured alone or with a monolayer of equine oviduct epithelial cells. Of 5 embryos cultured alone, 3 contained 12-20 cells, 1 was at the morula stage and 1 reached the blastocyst stage after 4 days. Of 5 embryos co-cultured with oviduct cells, 2 contained 12-16 cells, 1 was at the morula stage and 2 reached the blastocyst stage after 4 days. After 2 more days, the blastocysts showed only delayed development; there was no capsule, and limited increase in size. Equine embryos can develop in vitro from 4-8 cells to the blastocyst stage, in co-culture with equine oviductal monolayers and also without cellular support. The number of embryos studied was too small for us to draw conclusions about the benefits of co-culture.
Animals↗
The effect of cryopreservation on the metabolic activity of day-6.5 horse embryos.
The decrease in embryo viability caused by cryopreservation may be due, in part, to metabolic disturbances. To determine the effect of cryopreservation on metabolism, Day -6.5 horse embryos were either frozen and thawed using glycerol as the cryoprotectant, given only the glycerol treatment or washed an equal number of times in phosphate buffered saline (PBS). Before and after treatment, individual embryos were incubated with L-[14C(U)]-glutamine, to measure Krebs cycle activity, and D-[5-3H]-glucose, to measure Embden-Meyerhof pathway activity. Before treatment, glucose metabolism ranged from 110-625 pmol/2 h and glutamine metabolism from 4.1-15.9 pmol/2 h, both being highly correlated with embryo volume. Mean glucose metabolism in the control group increased 76% between the pre-treatment and post treatment measurements compared with 1% in the pooled treated groups, whereas mean glutamine metabolism increased only 10% in the control group but 50% in the treated embryos. Before treatment, there was no difference in mean ratio of glucose to glutamine metabolism between groups, but after treatment this ratio was almost 2-fold greater in the control group than in the treated group. These results indicate that cryopreservation inhibits anaerobic glucose metabolism and stimulates aerobic glutamine metabolism. However, this is an effect of the cryoprotectant, rather than of freezing and thawing.
Animals↗
Current status of whole-body counting as a means to detect and quantify previous exposures to radioactive materials. Whole-body Counting Working Group.
This report discusses the principles, techniques, and application of whole-body counting with respect to previous radiation exposure. Whole-body counting facilities are located nationwide and have a wide range of capabilities. A listing of these facilities is provided in Appendix A. However, only a few facilities are truly state-of-the-art and have the sophisticated capabilities required to attempt detection of low-level activity in vivo. Measurements made many years after exposure can be extremely difficult to interpret. The precision and accuracy of resulting dose estimates are functions of such factors as the assumptions made concerning intake, time since intake, radionuclide metabolism, and level of intake. The indiscriminate application of metabolic models to current body contents or minimum detectable amounts of radionuclides with relatively short effective half-lives (such as 137Cs) can lead to absurd results when used as a basis for calculating intakes 25 and 40 y ago. Skull counting for 90Sr-90Y and 239,240Pu can set upper limits on possible uptakes and radiation doses, but in the case of 239,240Pu, the limits are rather high. In both cases, the accuracy of the limits depends on the metabolic models used in the calculations. These models (ICRP 1979) were developed to set safety standards for the intakes of radionuclides by workers and are not intended to be used to back-calculate uptakes and radiation doses from measurements made long after the uptake. There are, therefore, large uncertainties in any conclusions derived from these calculations. The experience gained over the years with whole- and partial-body counting has consistently shown that they are of little use in determining body contents of radionuclides resulting from exposure to weapons debris decades earlier. The development of new detectors such as an array of lithium-drifted silicon devices offers some hope of lowering the minimum detectable amount (MDA) for Pu and Am, but such detectors are still several years from routine application and do not represent current state-of-the-art. Furthermore, it is doubtful that such improvements will be sufficient to meet the need of assessing radiation exposures that occurred decades earlier.
Accidents↗
Genetic contributions to T-cell recognition in murine lupuslike autoimmune disease.
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Animals↗
A role for clonal inactivation in T cell tolerance to Mls-1a.
Clonal deletion plays a major part in the maintenance of natural self-tolerance in both normal and transgenic mice. Self antigens that are expressed in the thymus result in the physical elimination of autoreactive thymocytes at a particular stage in their development. For example, the majority V beta 6- and V beta 8.1-bearing T cells that recognize the minor lymphocyte-stimulating antigen, Mls-1a (ref. 10) , are clonally deleted in the thymuses of normal mice and transgenic mice expressing Mls-1a (refs 2, 3, 9). In contrast, a very different mechanism of tolerance involving the functional inactivation, but not elimination, of autoreactive cells, termed clonal inactivation or clonal anergy, has been implicated in some experimentally manipulated systems of tolerance. To test further the mechanisms involved in self-tolerance, we have generated transgenic mice expressing a V beta 8.1 beta chain on greater than 95% of peripheral T cells and have tested tolerance to Mls-1a in these mice. Surprisingly, a significant fraction of the CD4+ peripheral cells that survived deletion were non-responsive in vitro to any stimulus tested. Naturally occurring tolerance to a self antigen expressed in the thymus can thus be mediated by clonal anergy, as well as by clonal deletion.
Animals↗
Characterization of a rat monoclonal antibody specific for a determinant encoded by the V beta 7 gene segment. Depletion of V beta 7+ T cells in mice with Mls-1a haplotype.
We have generated a rat mAb, TR310, which recognizes a determinant encoded by the murine V beta 7 gene segment of the TCR. TR310 immunoprecipitates TCR from cell lysates, co-modulates with CD3, and can be used for immunofluorescence staining of T cells. By using this antibody, we found that the average percentage of V beta 7+ peripheral T cells in Mls-1b mice was 3.8%, but only 0.8% in Mls-1a mice. A similar difference was also observed in the mature TCRhi thymocyte subsets, suggesting that V beta 7+ T cells are deleted during intrathymic maturation in Mls-1a mice. TR310 should prove to be a valuable reagent in further studies of the TCR repertoire and the analysis of factors which alter it.
Animals↗
Requirement for cotolerogenic gene products in the clonal deletion of I-E reactive T cells.
T cells that express the T cell receptor V beta 5.2 domain react with the class II major histocompatibility complex (MHC) molecule I-E, and V beta 5.2+ T cells are deleted in mouse strains that express I-E glycoproteins. By examination of genetically defined recombinant inbred (RI) mouse strains, it was found that the deletion was dependent on the expression of I-E and one of a limited number of non-MHC gene products (cotolerogens). The gene encoding one of these cotolerogens maps to chromosome 12 and is linked to the endogenous provirus Mtv-9. These observations suggest that the I-E-mediated and minor lymphocyte-stimulating antigen (Mls)-mediated deletions of alpha beta T cells from the repertoire are similar; both require the expression of a class II MHC glycoprotein and a second non-MHC gene product.
Animals↗