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Biomedical subjects

L Reeve

Publications and source records attributed to L Reeve.

10 recordsLinked to original sources
PubMed2004

Endometriosis affects sperm-endosalpingeal interactions.

BACKGROUND: The interaction between spermatozoa and the epithelium of the isthmic region of the uterine tube is thought to be an important part of the mechanisms of sperm transport to the site of fertilization and in preparing them for fertilization. However, it is unclear whether a dysfunction of this mechanism may contribute to subfertility in some individuals. METHODS: The sperm-binding characteristics of the epithelium from the uterine tubes of three groups of women were examined: (i) eight with pelvic endometriosis (not involving the uterine tubes); (ii) five women who had been receiving zoladex injections to control their symptoms; and (iii) as controls 10 women undergoing an elective procedure for benign gynaecological problems but with no other pathology of the reproductive tract. RESULTS: Significantly more spermatozoa bound per unit area to the ampullary epithelium of the uterine tubes taken from women with a previous diagnosis of endometriosis. CONCLUSIONS: These findings suggest that the characteristics of sperm binding to tubal epithelium may be disrupted in women with a gynaecological pathology such as endometriosis. It is suggested that this may have the potential to interfere with the availability of freely motile spermatozoa, of the appropriate physiological status, to take part in fertilization. This may be a newly described mechanism by which endometriosis can cause infertility.

Cell Adhesion↗
PubMed2003

Does the Arg-Gly-Asp (RGD) adhesion sequence play a role in mediating sperm interaction with the human endosalpinx?

BACKGROUND: Sperm from several species, including the human, make direct contact with the endosalpinx. Although this is known to be beneficial to sperm function, the specific mechanisms mediating the adhesion are poorly understood. METHODS: Short linear oligopeptides containing the amino acid sequence Arg-Gly-Asp (RGD) or a scrambled sequence (GRGES) were incorporated into an established sperm-endosalpingeal binding assay. In addition, the ability of fluorescent latex beads coated with an RGD oligopeptide to bind specifically to sperm and/or epithelium was also determined. RESULTS: Significantly fewer sperm associated per field of isthmic epithelium in the presence of 62.5 micro mol/l GRGDTP (1.18 +/- 0.41; mean +/- SEM, P < 0.05) and 250 micro mol/l RGDV (1.17 +/- 0.29; P < 0.01) compared with the control incubation (3.34 +/- 0.45). There was no difference in sperm binding to ampullary epithelium in the presence of any of the oligopeptides tested. Moreover, no beads were observed bound to sperm whereas significantly more RGD-coupled beads bound to isthmic epithelium compared with ampullary epithelium (1.47 +/- 0.26 versus 0.72 +/- 0.16 P < 0.01) and this increased in a dose-dependent manner. CONCLUSIONS: These findings indicate that the recognition between the RGD sequence and integrin receptors may contribute to the interaction between sperm and the human endosalpinx in the isthmic but not in the ampullary region of the uterine tube.

Binding, Competitive↗
PubMed1999

Cord blood progenitor cells have greater transendothelial migratory activity and increased responses to SDF-1 and MIP-3beta compared with mobilized adult progenitor cells.

When cord blood is used as a source of haemopoietic stem cells for transplantation, fewer cells are required per kg of recipient. This greater engraftment efficiency of cord blood cells may relate to an increased ability to traverse sinusoidal endothelium, a crucial step in the homing of stem cells. We report that freshly isolated cord blood progenitors migrated more efficiently than mobilized adult cells. Cord blood progenitors responded rapidly to growth factor stimulation with an increase in migratory ability within 24 h whereas mobilized adult cells responded only after 72 h (P < 0.01). Cord blood cells also exited G0/G1 rapidly; after 24 h of growth factor exposure, 20.2 +/- 1.2% of cord blood CD34+ cells were in S + G2/M compared to 6.9 +/- 1.2% of adult CD34+ cells (P < 0.01). Proliferating CFC migrated more efficiently (13.3 +/- 3.4% for GM-CFC) than non-proliferating CFC (1.4 +/- 0.5%, P < 0.01) as determined using a 3H-thymidine suicide assay. Cord blood progenitor cells also demonstrated a greater transmigratory response to chemokine stimulation compared with adult cells; this was manifested as a differential response of freshly isolated cells to SDF-1, and of growth factor activated cells to MIP-3beta. Finally, cord blood CD34+ cells express higher levels of the chemokine receptor for SDF-1, CXCR4, when compared with mobilized adult CD34+ cells (P < 0. 05).

Adult↗
PubMed1997

New technology in the analytical cell sciences: the laser scanning cytometer.

New technologies are making a major contribution to progress in applied clinical research in surgical oncology. The laser scanning cytometer is a new machine which combines the analytical capabilities of flow cytometry with the ability to inspect and visualize labelled cells and particles. This substantially reduces the uncertainty associated with assays in a wide range of surgical oncology research applications. This article introduces this new technology.

Equipment Design↗
PubMed1993

A parametric variation of delayed reinforcement in infants.

This study is an exploration of the parameters of delayed reinforcement with 6 infants (2 to 6 months old) in two experiments using single-subject repeated-reversal designs. In Experiment 1, unsignaled 3-s delayed reinforcement was used to increase infant vocalization rate when compared to a differential-reinforcement-of-other-than-vocalization condition and a yoked, no-contingency comparison condition. In Experiment 2, unsignaled 5-s delayed reinforcement was used to increase infant vocalization rate when compared to an alternating-treatments comparison condition. The alternating-treatments comparison consisted of 3-min components of differential reinforcement of other behavior and 3-min components of a nontreatment baseline. Successful conditioning was obtained in both experiments. These results contrast with those of previous infancy researchers who did not obtained conditioning with delays of 3 s and who attributed their findings to the limitations of the infant's memory capacity. We present an alternative conceptual framework and methodology for the analysis of delayed reinforcement in infants.

Behavior↗
PubMed1992

Effects of delayed reinforcement on infant vocalization rate.

Three previous studies have failed to demonstrate conditioning in infants using a 3-s delay of reinforcement. The effects of a delayed reinforcement schedule on vocalization rates therefore were explored in a single-subject repeated-reversal experimental design for 3 4- to 6-month-old normally developing infants. Each infant received delayed social reinforcement from his or her parent for vocalizing. The comparison condition was a schedule of differential reinforcement of behavior other than vocalizations to control for elicitation by social stimulation. An operant level of infant vocalizations was the initial condition, after which the differential reinforcement schedule was implemented in an across-subjects multiple baseline design. Infants' vocalization rates increased above levels measured during differential reinforcement following onset of the delayed reinforcement condition. Also, vocalization rates decreased during differential reinforcement compared to operant levels. The successful use of delayed reinforcement schedules with infants in this study, as opposed to others, is discussed in terms of procedural differences among them.

Arousal↗
PubMed1991

Generalized vocal imitation in infants.

Effects of modeling and response-contingent social praise on the vocal imitation of three 9- to 13-month-old infants were analyzed. Three infants and parents participated in 2 to 4 experimental sessions a week for 2 to 4 months. During each 20-min-long session, the parent presented vocal models for the infant to imitate. During the model-alone condition, no social praise was programmed for infant imitation. During the model-and-praise condition, social praise was provided by the parent for infant imitation on training trials, but not probe trials. All three infants showed systematic increases in matching during training trials following the introduction of the model-and-praise condition. Although matching during probe trials was not directly reinforced, probe-trial responding increased systematically with training-trial responding. Furthermore, non-matching infant vocalizations did not increase systematically with the introduction of the model-and-praise procedure. Together these findings provide a demonstration of generalized vocal imitation in infants, a population in which it had not previously been shown to occur.

Female↗
PubMed1983

Studies on the site of 1,25-dihydroxyvitamin D3 synthesis in vivo.

Anephric, vitamin D-deficient male rats were injected with a physiologic dose of 25-hydroxy[26,27-3H]vitamin D3 (specific activity of 160 Ci/mmol), and 18-20 h later, intestine, bone, and serum were analyzed by high performance liquid chromatography for 1,25-dihydroxy-[26,27-3H]vitamin D3. Identical studies were carried out using sham-operated rats and rats with ligated ureters. No 1,25-dihydroxy[26,27-3H]vitamin D3 was detected in the tissues from anephric rats, while large amounts were detected in sham-operated and ureteric ligated controls. This result demonstrates that in the nonpregnant rat, 1,25-dihydroxyvitamin D3 is either not synthesized or is synthesized in vanishingly small amounts in bone and intestine in vivo, casting considerable doubt of the physiological importance of reports of in vitro synthesis of 1,25-dihydroxyvitamin D3 by cells in culture derived from bone and elsewhere.

Animals↗
PubMed1975

Structural analogs of 1alpha,25-dihydroxycholecalciferol: preparation and biological assay of 1alpha-hydroxypregnacalciferol.

The synthesis of 1alpha-hydroxypregnacalciferol, a side chain analog of 1alpha,25-dihydroxycholecalciferol (1alpha,25-dihydroxyvitamin D3), is described. Pregnenolone acetate was converted in five steps to 5-pregnen-1alpha,3beta-diol. Conversion of the diol to pregna-5,7-diene-1alpha,3beta diol diacetate followed by ultraviolet irradiation gave the corresponding previtamin derivative. Thermal isomerization, hydrolysis and chromatography then furnished the desired analog, 1alpha-hydroxypregnacalciferol. The compound was tested in vivo for its effect on intestinal calcium transport, serum calcium and phosphate levels and bone calcification, and in vitro for its effect on bone resorption. When given to intact rats, either as a single dose or in repeated daily doses, the analog even at high dose levels, exhibited no biological activity. The compound stimulated bone resorption in vitro, but only at high concentrations.

Animals↗