Biomedical subjects

E Palmer

Publications and source records attributed to E Palmer.

At least 55 records · Page 3Linked to original sources

PubMed1998

Evaluation of a computer based package on electrocardiography.

BACKGROUND: Opportunities for interactive learning in electrocardiography are limited--particularly at postgraduate level. In medical education, increasing use is being made of the electronic medium and various materials have been developed to improve clinicians' skills. AIMS: To test and evaluate the learning of electrocardiography among health professionals. METHODS: A software package, containing a tutorial on electrocardiography and a self-assessment programme of 140 electrocardiograms (ECGs) was constructed. Seventy-two health professionals were recruited into the study and tested before and after the study period. Participants were randomly allocated to one of three groups: control (no study material), tutorial or computer. The tutorial group participated in a series of tutorials and the computer group were provided with a CD-ROM containing study material for them to use in their own time. The results were assessed for statistical significance between all groups using analysis of variance techniques. RESULTS: Sixty-one individuals completed the study. Each of the three groups was pre and post tested on their knowledge of electrocardiography and their ability to interpret ECGs. The computer group was the only group to achieve a significant increase in performance in their knowledge on electrocardiography and in their ability to interpret ECGs. CONCLUSIONS: Suitably structured computer programmes are effective in helping clinicians understand electrocardiography and interpret ECGs.

Analysis of Variance↗

PubMed1997

Signaling efficiency of the T cell receptor controlled by a single amino acid in the beta chain constant region.

A single amino acid residue, Gln136, located within the connecting peptide domain of Cbeta controls the ability of the alpha/beta TCR to transmit a full signal. TCRs in which this Cbeta residue is mutated to Phe, the residue found in TCR-gamma, are unresponsive to antigenic ligands. Interestingly, this Cbeta residue is either polar or charged in every species studied thus far, including the trout and the skate. In contrast, the analogous residue in Cgamma is always hydrophobic. In spite of their compromised antigen responsiveness, the mutant TCR complex contains the CD3-gamma, -delta, -epsilon, and -zeta chains, and undergoes zeta chain phosphorylation and ZAP-70 recruitment. However, the biological response of the mutant TCR could be rescued with a calcium ionophore, implying that mutant TCRs are defective in generating a calcium-mediated signal. The implications of the differences between Cbeta and Cgamma are considered.

Amino Acid Sequence↗

PubMed1997

Equine frozen semen: freezability and fertility field results.

The freezability of stallion semen defined as the number of selected ejaculates/total number of ejaculates frozen from 161 different stallions was analyzed. Of the stallions, 19, 30, 27 and 24% had a freezability of 0%, 0 to 33%, 33 to 66%, over 66%, respectively In 85 different stallions, the correlation of freezability between first and second year was 0.60 (P < 0.001). The relationship between fertility with fresh and frozen semen and freezability was analyzed in 40 stallions whose freezability and fertility information was recorded during 5 years. There was a strong relationship between fertility of fresh semen and semen freezability (P < 0.001). However, the relationship between fertility of frozen semen and freezability was not as marked (P < 0.05). Analysis of the field fertility per cycle results when mares were bred with 300 or 150 x 10(6) total spermatozoa at different frequencies until ovulation indicated that mares that were inseminated 2 times or more per estrus show an improved fertility in comparison with mares inseminated only once (34%, n = 1576 vs 26%, n = 626; P < 0.001). Foaling rate when mares were inseminated with frozen semen (1858 mares during 8 breeding seasons) was mainly influenced by mare age (< 16 years: 54% vs >/= 16 years 42% p < 0.001). Date of first insemination (before May 15: 58% vs after May 15: 37%) also had a significant effect on foaling rate (P < 0.001).

Journal Article↗

PubMed1997

T cell receptor alpha-chain tail is required for protein kinase C-mediated down-regulation, but not for signaling.

Antigen stimulation through the T cell receptor (TCR) induces phosphorylation of the associated CD3 gamma delta epsilon- and zeta-chain cytoplasmic tails. These events lead to the induction of the intracellular signaling pathways with concomitant receptor down-regulation. The TCR is down-regulated from the cell surface by the activation of protein kinase, C (PKC) and subsequent serine phosphorylation of the CD3 gamma-chain. We report here that the TCR alpha-chain cytoplasmic tail is also necessary for PKC-mediated internalization of the TCR complex. The requirement for the TCR alpha-chain cytoplasmic tail is specific for internalization of the TCR complex, since down-regulation of CD4 is still intact in hybridoma cells expressing a tailless TCR alpha-chain. The absence of TCR internalization directly correlates with defective PKC-mediated phosphorylation of the CD3 gamma-chain. Despite deficient PKC-mediated TCR down-regulation, the tailless alpha beta TCR still transduces antigenic signals resulting in the production of interleukin-2. Although the TCR tails are not obviously required for signal transduction, the TCR alpha-tail may serve as a targeting domain for PKC-mediated down-regulation of the TCR complex.

Amino Acid Sequence↗

PubMed1997

Effect of milk fractions on survival of equine spermatozoa.

Milk-based semen diluents are known to be practical and effective in protecting equine spermatozoa during storage. Due to complex composition of milk, the components which are beneficial or harmful to spermatozoa are unknown. To address these unknowns the effect of various milk fractions on motility of stallion spermatozoa was evaluated. The fractions tested were native phosphocaseinate (NPPC), beta-casein, whey protein concentrate (WPC), alpha-lactalbumin, beta-lactoglobulin, microfiltrate, and ultrafiltrate. The standard reference diluents were INRA 82, commercial skim milk, and Hank's salts solution supplemented with Hepes, glucose, lactose (HGLL) supplemented with BSA. After 48 and 96 h storage at 4 or 15 degrees C some milk fractions (ultrafiltrate, microfiltrate, and alpha-lactalbumin fraction) decreased spermatozoal survival. Others (beta-lactoglobulin (BL) and native phosphocaseinate) were protective. Native phosphocaseinate (NPPC) at milk concentration afforted better protection than did the standard reference diluents. The optimal concentration of beta-lactoglobulin afforted significantly better protection than did BSA. The protection afforded by native phophocaseinate was not synergistic with beta-lactoglobulin. This implies a similar mechanism of protective action of these two components. Semen diluted in HGLL supplemented with NPPC (HGLL-NPPC) or in INRA 82 and stored 24 h at 15 degrees C or 4 degrees C, respectively, produced no difference of spermatozoal motility. However, fertility of semen stored in HGLL-NPPC (60%) was higher (p < 0.05) than that stored in INRA 82 (36%).

Journal Article↗

PubMed1997

New staining methods for sperm evaluation estimated by microscopy and flow cytometry.

New staining methods and automated instruments are now available to evaluate the sperm cell in vitro. Individual compartments of the sperm cell, such as the nucleus and the plasma and acrosomal membranes, may be investigated, as well as the cell function as shown by mitochondria activity and capacitation. Various probes are used and they can be analyzed by direct light or fluorescent microscopy or by flow cytometry. The automated instruments allow objective and accurate analysis and quantification as well as the ability to evaluate large population of cells in a shorter time, thus providing accurate evaluation of sperm quality. However, before these test can be recommended for routine clinical and investigational use, in the stallion, they need to be confirmed on a larger number of stallions and their correlation with traditional semen parameters and with stallion fertility has to be demonstrated.

Journal Article↗

PubMed1997

Neuronal cell loss in the CA3 subfield of the hippocampus following cortical contusion utilizing the optical disector method for cell counting.

Unilateral cortical contusion in the rat results in cell loss in both the cortex and hippocampus. Pharmacological intervention with growth factors or excitatory neurotransmitter antagonists may reduce cell loss and improve neurological outcome. The window of opportunity for such intervention remains unclear because a detailed temporal analysis of neuronal loss has not been performed in the rodent cortical contusion model. To elucidate the time course of hippocampal CA3 neuronal death ensuing cortical contusion, we employed the optical disector method for assessing the total number of CA3 neurons at 1 and 6 hours, 1, 2, 10, and 30 days following injury. This stereological technique allows reporting of total cell numbers within a given region and is unaffected by change in the volume of the structure or cell size. A rapid and significant reduction in neurons/mm3 in the ipsilateral CA3 field was observed by 1 h following trauma. However, a significant increase in neurons/mm3 was seen at 30 days postinjury. This surprising finding is a result of CA3 volume shrinkage and redistribution of CA3 neurons. Utilization of the optical disector reveals that regardless of an increase in neurons/mm3 at 30 days following injury, CA3 cell loss reaches 41% of control animals by 1 day posttrauma and remains near that level at all subsequent time points examined. It is estimated that there are about 156,000 neurons in the CA3 region in control animals. By 1 h following cortical contusion the cell population decreases to 93,000 neurons indicating a very rapid cell loss. This suggests a window of less than 24 h for pharmacological intervention in order to save CA3 neurons following cortical contusion.

Animals↗

PubMed1997

Equine oocyte competence for nuclear and cytoplasmic in vitro maturation: effect of follicle size and hormonal environment.

Equine oocyte competence after in vitro maturation (IVM) was investigated in terms of the diameter of the follicle of origin and the stage of the estrous cycle, with three criteria of maturation: nuclear stage after DNA Hoechst staining, meiotic spindle morphology after tubulin immunocytochemical staining, and cortical granule localization after lectin labeling. Seven successive in vivo ultrasound-guided follicular punctures were performed on 10 cyclic saddle mares, alternatively at the end of the follicular phase (after induction of ovulation with a gonadotropin injection) and in midluteal phase (with or without a gonadotropin injection). Expanded cumulus-oocyte complexes (COCs) were stained at collection, and compact COCs were stained after in vitro culture. They were observed under a confocal microscope. Successive punctures on one mare provided 0.9 preovulatory COCs and 8 immature COCs per 22 days. Among the preovulatory oocytes, 55% had completed nuclear and cytoplasmic maturation, 86% of which displayed a normal meiotic spindle. Of the 262 oocytes cultured in vitro, 37% completed nuclear maturation. The nuclear and cytoplasmic maturation rate significantly increased with follicle diameter. The IVM rate tended to be higher in follicular phase and tended to increase in luteal phase with the gonadotropin injection. The meiotic spindle morphology was not significantly different between the classes of follicular diameters. This study provided the opportunity to increase the number of characterized oocytes collected per cycle and per mare. This is the first report showing the progressive acquisition of meiotic competence in the equine oocyte during antral follicle growth and is the only description of the equine meiotic spindle.

Animals↗

PubMed1997

A comparison of the biochemical composition of equine follicular fluid and serum at four different stages of the follicular cycle.

Samples of blood and follicular fluid were recovered from 27 Welsh Pony mares at 4 distinct stages of follicular development. Eighteen biochemical parameters were measured in each sample, including sodium, potassium, chloride, glucose, urea, creatinine, calcium, inorganic phosphate, total bilirubin, total protein, albumin, magnesium, triglyceride, total cholesterol, nonesterified fatty acids, alkaline phosphatase, gamma-glutamyltransferase and aspartate aminotransferase. The concentrations of progesterone, 17beta oestradiol and testosterone, pH and osmolarity, were also measured in all the follicular fluid samples. The concentrations of all proteins measured were lower in follicular fluid than serum whereas the reverse was true in the case of the lipids. Analysis of variance indicated that serum and follicular fluid concentrations of most of the parameters measured varied in parallel.

Animals↗

PubMed1997

Follicular fluid is not a compulsory carrier of the oocyte at ovulation in the mare.

The aim of this study was to test the possibility that ovulation can occur from a preovulatory follicle emptied of its follicular fluid. Transport of the oocyte into the oviduct and fertilisation in 29% of cases demonstrated that ovulation can occur in the absence of follicular fluid but the higher fertility achieved in control mares (62.5%) suggested that follicular fluid does serve a role during ovulation, fertilisation and oviductal transport. Injection of horse oocytes into preovulatory follicles in mules after removal of the follicular fluid, followed by insemination of the mules with horse semen, resulted in the production of one horse x horse embryo.

Animals↗

PubMed1997

Transfer of immature oocytes to a preovulatory follicle: an alternative to in vitro maturation in the mare?

In the mare, success rates for the in vitro maturation of oocytes are low. Accordingly, we attempted to determine if immature oocytes could be matured in vivo by injecting them into a preovulatory follicle. Groups of 3-9 oocytes collected from donor mares were transferred under ultrasound control into the preovulatory follicle of a recipient mare that was treated with crude equine pituitary gonadotrophin (CEG) to induce ovulation. Just before ovulation (34 h post treatment) the preovulatory follicle of the recipient mare was punctured to collect both the transferred and the indigenous oocytes to analyse the stages of nuclear maturation. The transfer technique did not impair significantly the final maturation of the recipient preovulatory follicle. The indigenous oocytes within the recipient follicles were recognisable by their larger expanded cumulus of yellow colouration due to high hyaluronic acid content; 7/12 of these oocytes were mature (metaphase II). Around half (42/86; 49%) of the oocytes transferred to preovulatory follicles were recovered subsequently. Most of them showed cumulus expansion (41/42, 6 of which were rich in hyaluronic acid), 13 (32%) were mature, 15 (36%) were immature and 13 (32%) were degenerate. When the indigenous oocyte of the recipient mare was mature, 38% of the transferred oocytes were mature, this rate being no different from the in vitro maturation rate of 46%. This study showed that in vivo maturation of immature oocytes by transfer into a preovulatory follicle in a recipient mare is possible. The maturation rate is not different from the in vitro maturation rate. The technique allows the generation of mature oocytes that have an expanded cumulus rich in hyaluronic acid, similar to the situation in preovulatory oocytes. This result has not been obtained in vitro previously.

Animals↗

PubMed1997

Parentage testing of Day 10 equine embryos by amplified PCR analysis of microsatellites.

Paternity analysis was performed on the DNA of 21 equine embryos collected nonsurgically 10 days after ovulation from known mares, but involving 3 possible sires. After extraction, the DNA of each embryo was typed by radioactive PCR amplification using 10 characterised microsatellites; HMS 1, 2, 5, 6, 7 and 8 (Guérin et al. 1994) and HTG 3, 4, 6 and 10 (Marklund et al. 1994). The 21 dams and 3 sires were genotyped using DNA extracted from blood and amplified by PCR. After electrophoresis and autoradiography of the PCR products of the embryo and parents, the alleles of the embryo were compared to those of the dam to identify those of maternal origin. The paternal alleles were then searched for within the genotype of the 3 sires, and the stallion(s) that exhibited the particular allele was said to be compatible with the embryo for this microsatellite. In this way, the true sire was identified correctly for all 21 embryos.

Alleles↗

PubMed1997

Effect of anti-freeze protein (AFP) on the cooling and freezing of equine embryos as measured by DAPI-staining.

Equine embryos recovered on Day 6 after ovulation were cooled to +4 degrees C, or frozen with AFP alone or together with glycerol. Twenty embryos (140-200 microm in diameter) were randomly assigned to 6 treatment groups. In the first 3 groups, the embryos were cooled from room temperature to +4 degrees C at a rate of 3 degrees C/min and warmed again at a rate of 32 degrees C/min in a programmable freezer. In the second 3 groups, the embryos were frozen using a standard protocol, stored in liquid nitrogen for 5-7 days and then thawed in a 37 degrees C waterbath. After cooling/warming or freezing/thawing all the embryos were stained with DAPI. The percentage of dead cell area was significantly lower in the cooling groups than in the freezing groups and no significant differences were apparent between the cryoprotectants used in the study.

Animals↗

PubMed1997

The effect of sucrose in the thawing solution on the morphology and mobility of frozen equine embryos.

Seventy-five embryos were collected 6 days after ovulation. Sixty embryos were frozen in straws using glycerol as the cryoprotectant in an automatic freezer. In Experiment 1 the freezing and thawing media were supplemented with 1.3 g/l PVP; in Experiment 2 the supplement was 5% FCS. The embryos were thawed for 30 s at +37 degrees C in a waterbath. In Experiment 1 glycerol was removed from 10 embryos in 6 steps. In 10 other embryos, glycerol and sucrose were both removed from the medium in 6 steps. After glycerol and sucrose removal, the embryos were stained with 4',6'-diamidino-2-phenylindole (DAPI) to count the percentage of dead cells. Fluorescent rate (FR) was defined as a ratio of fluorescent area versus total area. Mean (+/- s.d.) FR in this experiment was significantly lower (P<0.01) in embryos thawed with sucrose (0.28 +/- 0.13) than in embryos thawed with glycerol alone (0.53 +/- 0.25). In Experiment 2, 40 embryos were frozen and glycerol, with or without sucrose, was removed after thawing as for Experiment 1. Ten embryos in both groups were stained with DAPI. All the frozen-thawed embryos were transferred nonsurgically to recipient mares. Fourteen fresh embryos were transferred as controls, 7 of which were stained with DAPI before transfer. There was no difference in pregnancy rates between DAPI-stained versus nonstained embryos, indicating that the staining process had no negative effects on embryonic survival. Insufficient embryos were transferred to be able to demonstrate any difference in pregnancy rates between embryos thawed with or without sucrose in the medium.

Animals↗

PubMed1997

Timing of in vivo maturation of equine preovulatory oocytes and competence for in vitro maturation of immature oocytes collected simultaneously.

The objects of this study were to monitor the development of the cumulus complex and nuclear maturation in oocytes recovered from preovulatory follicles following treatment to induce ovulation and to investigate the in vitro maturation competence of oocytes recovered from smaller nonpreovulatory follicles of varying size. All follicles > or =5 mm in pony mares were individually punctured at 0, 6, 12, 24 and 35 h after an injection of LH to induce ovulation. The recovery rates of oocytes were 64% from 55 preovulatory follicles, 22% from 32 subordinate follicles and 52% from 227 small follicles. Cumulus expansion of the preovulatory oocytes occurred at 12 h post LH treatment while the metaphase I and II components of nuclear maturation were not completed until 24 and 35 h post LH respectively. For nonpreovulatory follicles, the frequency of atresia and oocyte competence for in vitro nuclear maturation both increased with increasing follicular size.

Animals↗

PubMed1996

A motif within the T cell receptor alpha chain constant region connecting peptide domain controls antigen responsiveness.

Mutant alphabeta TCRs were generated by replacing domains of the alpha and beta chain constant regions with homologous domains from TCR delta and gamma chains, respectively. Chimeric TCRs in which the alpha chain contains TCR delta chain sequences within the connecting peptide domain are unresponsive to alloantigens and superantigens, and have defective interactions with the CD3/zeta complex. Although these antigen-unresponsive TCRs undergo zeta chain phosphorylation upon stimulation with superantigen, they do not generate a full signal capable of producing IL-2. Mutant TCRs acquire signaling activity with a combination of superantigen and calcium ionophore, indicating a defect in calcium-mediated signaling. Finally, a conserved motif, FETDxNLN, present in the alpha chain connecting peptide domain, is disrupted in all signaling-defective TCRs. This conserved alpha chain connecting peptide motif might mediate the transfer of signals from the alphabeta heterodimer to the CD3/zeta complex.

Amino Acid Sequence↗

PubMed1996

Associated postural adjustments are impaired by a lesion of the cortex.

A ballistic movement of one arm may be accompanied by contractions of contralateral postural muscles known as "associated postural adjustments." Ballistic movements are considered to involve the motor cortex, but it is not known where associated postural adjustments are generated. We recorded the EMG activity in the deltoid and latissimus dorsi muscles during ballistic abduction of the arm in 10 normal subjects and five subjects with lesions of the motor cortex. When subjects with cortical lesions abducted the unaffected arm, the associated postural adjustment in the contralateral latissimus dorsi was significantly smaller than normal. We argue that postural adjustments, like ballistic movements, require the participation of the motor cortex.

Adult↗

PubMed1995

A dominant T cell receptor beta-chain in response to a short ragweed allergen, Amb a 5.

HLA-DR alpha, beta 1 *1501 (and the closely related DR alpha, beta 1 *1502) heterodimers are the primary class II MHC restriction elements controlling T cell responses to a ragweed pollen allergen, Amb a 5 (M(r) = 5000). Using a novel, quantitative, competitive PCR (QC-PCR) assay and a TCR beta-gene internal standard (IS), we have examined the TCR beta-gene use in Amb a 5-specific T cells. Multiple TCR V beta (and V alpha) genes were found in polyclonal T cell lines from two unrelated subjects, and 30% of the cells were stained positive for V beta 5.2/5.3 as judged by a flow cytometry analysis. An Amb a 5-specific Th2 clone (AP1.2) was found to express V beta 5.2 (and V alpha 8) and to have a unique V-D-J junctional region sequence. To determine the relative frequency of clone AP1.2 beta-gene expression in the polyclonal T cell lines and in the PBMC using a QC-PCR assay, we first created a TCR IS by duplicating the J beta 1.5 gene segment of the AP1.2 beta-gene. A QC-PCR assay was performed using the modified AP1.2 beta-gene as a competitor and a V beta 5.2 or a D beta-specific primer, each paired with a C beta primer. Results showed the presence of 30% of AP1.2 beta transcripts in the polyclonal T cell lines, but no detectable amplified products were found in the total RNAs (200 ng) of autologous PBMC. These findings were confirmed by sequencing independent clones of PCR-amplified V beta 5.2-C beta fragments (from two unrelated subjects) from each cell line, which suggested that the frequency of the clone AP1.2 beta sequence is quite low in the PBMC but is dominant in polyclonal Amb a 5-specific cell lines.

Allergens↗