Imaging flow cytometry to characterize the relationship between abnormal sperm morphologies and reactive oxygen species in stallion sperm

Low levels of intracellular reactive oxygen species (ROS) are essential for normal sperm function and are produced by sperm mitochondria as a byproduct of metabolism, but in excess, ROS can cause catastrophic cellular damage and has been correlated with infertility, poor sperm motility and abnormal morphology in humans. Stallion sperm motility is fueled predominantly by oxidative phosphorylation-produced ATP, requiring high basal rates of mitochondrial function. Consequently, whether elevated ROS production by stallion sperm is an indicator of dysfunctional or highly motile cells has been debated by researchers over the last decade. The objective of this study was to evaluate the relationship between various sperm morphologies and ROS production in fresh and cooled stallion semen by employing the novel method of imaging flow cytometry for stallion semen assessment. For evaluation of fresh semen, single ejaculates (n = 5) were collected from four resident stallions at the University of California, Davis. For the evaluation of 24-h cool-stored semen, single ejaculates were collected from stallions at Texas A&M University (n = 5) and shipped to the University of California, Davis overnight for evaluation. Ejaculate volume, sperm concentration and motility parameters were recorded. Samples were co-stained for viability and ROS detection with SytoxGreen™ and dihydroethidium (DHE), respectively, and evaluated with the Amnis® ImageStream® system (Luminex Corporation). Antimycin, an electron transport chain inhibitor that triggers ROS production (1 μM), was used as a positive control for DHE, while dead cells (2× snap frozen in liquid nitrogen) served as a positive control for SytoxGreen™. Unstained samples were also evaluated as controls. Imaging flow cytometric analysis was performed with the ideas® software (Luminex Corporation). Evaluated morphologies included abnormal head (AH), abnormal midpiece (AM), abnormal tail (AT), proximal cytoplasmic droplet (PD), or distal cytoplasmic droplet (DD), and morphologically normal (MN) cells. For fresh semen, an additional abnormality, coiled tail and midpiece (CTM) was assessed; 24-h cool-stored semen did not contain enough viable CTM cells for analysis. Only cells with obvious, single abnormalities were selected for the first portion of analysis to minimize subjectivity. Mixed effects modelling was used to evaluate the relationship between each morphologic classification and the corresponding DHE fluorescence intensity. Compared to the MN population, ROS production was significantly higher in viable cells with AH, PD and AM (p < .0001) in both fresh and cooled semen. CTM cells had significantly higher levels of ROS production compared to MN cells in fresh semen (p < .0001). There was no significant difference in ROS levels between MN cells and AT and DD cells in either fresh or cooled semen (p > .05). These results suggest that ROS generation is indicative of abnormal cell morphology and function and confirm that imaging flow cytometry is a valuable tool for the assessment of stallion semen.

Factors affecting intracellular calcium influx in response to calcium ionophore A23187 in equine sperm

BACKGROUND

Exposure to the calcium ionophore A23187 may present a "universal" sperm treatment for IVF, as it bypasses capacitation pathways. However, success in utilizing A23187 is variable, especially in equine spermatozoa. Notably, albumin is used during A23187 treatment but paradoxically is thought to suppress A23187 action. Essentially no critical data are available on the effects of A23187 and albumin concentrations, ratios, or addition protocols on changes in intracellular calcium ([Ca]_i ) in any cell type.

OBJECTIVE

To determine factors that affect the action of A23187 on [Ca]_i in equine and murine spermatozoa.

METHODS

Spermatozoa were loaded with Fluo-4 and changes in fluorescence after A23187 treatment were measured under various conditions using a microplate reader.

RESULTS

Concentrations of bovine serum albumin (BSA) and A23187, type of BSA, makeup of A23187 stock solutions (i.e., 1° stock (DMSO) or 2° stock made with medium, water or DMSO), order of addition of spermatozoa and A23187, incubation of media before sperm addition, species of spermatozoa, and time of addition of BSA all affected [Ca]_i in response to A23187 treatment. In equine spermatozoa already exposed to 10 µM A23187, addition of BSA to 33 mg/ml to "quench" the A23187 did not affect [Ca]_i . When this concentration of BSA was added to spermatozoa exposed to 1 µM A23187, [Ca]_i in murine spermatozoa returned to baseline, however, equine spermatozoa continued to exhibit increased [Ca]_i . Addition of BSA to 33 mg/ml to media containing 1 µM A23187, prior to addition of spermatozoa, completely inhibited change in [Ca]_i in both murine and equine spermatozoa.

CONCLUSION

These results represent some of the first critical data on the effects of albumin and other procedural factors on A23187-induced changes in [Ca]_i in any cell type. Our findings help to explain the variability in reported response of spermatozoa to A23187 among species and among laboratories.

Effect of intrauterine treatment with prostaglandin E2 prior to insemination of mares in the uterine horn or body

Two trials were conducted to investigate the effects of intrauterine infusion of PGE2 and uterine horn insemination on pregnancy rates in mares achieved by breeding with a suboptimal number of normal spermatozoa. Estrus was synchronized and mares were teased daily with a stallion to detect estrus. Mares in estrus were examined by transrectal palpation and ultrasonography to monitor follicular status. On the first day a 35-mm diameter follicle was present, hCG (1500 IU, iv) was administered and the mares were bred the next day. Mares (Trial 1, n = 34; Trial 2, n = 28) were inseminated with 25 million total spermatozoa from either a stallion with good semen quality (Trial 1) or poor semen quality (Trial 2). In each trial, mares were assigned to 1 of 4 treatment groups as follows: Group PGE-HI - infusion of 0.25 mg PGE2 into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the proximal end of the same uterine horn; Group PGE-BI - infusion of 0.25 mg PGE2 into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the uterine body; Group SAL-HI - infusion of 1 mL sterile saline into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the proximal end of the same uterine horn; or Group SAL-BI - infusion of 1 mL sterile saline into the proximal end of the uterine horn ipsilateral to the dominant follicle 2 h prior to insemination in the uterine body. After breeding, mares were examined daily by transrectal ultrasonography to confirm ovulation, and were re-examined 14 to 16 d after ovulation for pregnancy status. Data were analyzed by Chi-square. Overall pregnancy rates were 59% for stallion 1 and 29% for stallion 2. Group pregnancy rates did not differ for mares bred by either stallion (P > 0.10). Pregnancy rates were not altered by horn insemination for either stallion (P > 0.10). Intrauterine infusion of PGE2 improved pregnancy rate in mares bred by the stallion with good quality semen (P < 0.05), but did not alter pregnancy rate in mares bred by the stallion with poor quality semen (P > 0.10). Further research is warranted to determine if intrauterine infusion of PGE2 will enhance spermatozoal colonization of the oviduct and pregnancy rates in mares, and if PGE-treatment will improve pregnancy rates achieved by subfertile stallions.

Testicular and hormonal changes in stallions with thermally induced testicular degeneration

The scrota of three Pony stallions and one miniature horse were insulated for 36 h. Plasma testosterone concentrations decreased gradually and were significantly (P < 0.05) lower than pretreatment values at 16, 24, 30, 38 and 44 h after onset of scrotal insulation. Plasma LH and oestradiol concentrations were significantly (P < 0.05) decreased 18 h, and 24 and 26 h, after onset of scrotal insulation, respectively. Plasma FSH concentrations were significantly (P < 0.05) decreased 4 days after the insulation was removed. Decreases in the potential daily sperm output per Pony for early primary spermatocytes (34% decrease) and late primary spermatocytes (60% decrease) were observed in the testes of Pony stallions castrated 7 days after the insulation was removed. Decreases in the potential daily sperm output of all germ cell types were observed in the testes of the miniature horse castrated 24 days after the insulation was removed. Testosterone propionate in corn oil (5 mg in 1.05 ml testis) was injected into the vaginal space surrounding the testes of two Pony stallions 2 days before scrotal insulation and of one stallion whose scrotum was not insulated. The percentage of sperm of normal morphology in ejaculates decreased significantly (P < 0.05; n=3) 15-26 days after onset of insulation compared with pretreatment values. Circulating testosterone concentrations were maintained at pretreatment concentrations for 18 days after the scrotum was insulated, but this did not prevent deterioration in semen quality. Circulating LH and oestradiol concentrations decreased significantly by 2 days after injection of testosterone (P < 0.05). LH concentrations were decreased significantly (P < 0.05) from pretreatment values for 18 days after scrotal insulation and oestradiol concentrations were decreased significantly (P < 0.05) for 26 days. In conclusion, insulation of Pony scrota for 36 h reduced the yield of germ cells during spermatogenesis. A reduction in circulating testosterone concentrations occurred by 16 h after onset of scrotal insulation, which is probably the result of Leydig cell impairment. However, testosterone replacement therapy did not prevent deterioration of semen quality, which indicates that the primary cause of germ cell degeneration after thermal injury to the testes may not be impaired Leydig cell production of testosterone.

Administration of oxytocin immediately after insemination does not improve pregnancy rates in mares bred by fertile or subfertile stallions

It is probable that reduced pregnancy rates in mares bred to subfertile stallions is attributable, in part, to the reduced number of normal spermatozoa that colonize the oviduct. Administration of oxytocin stimulates both uterine and oviductal contractility. The hypothesis that oxytocin may enhance sperm transport to/into the oviducts, and thereby increase pregnancy rates, was tested in 2 trials. For both trials, fertile estrous mares with follicles > or = 35 mm in diameter were inseminated once at 24 h after administration of 1500 to 2000 U hCG. The inseminate dose was limited to 100 million spermatozoa in order to lower pregnancy rates and thus increase the chance of detecting a treatment effect. Pregnancy status was determined by transrectal ultrasound examination 14 to 16 d after insemination. In Trial 1, 49 mares were inseminated with 4 mL extended semen from 1 of 3 stallions (1 fertile and 2 subfertile males). Immediately after insemination, the mares were administered either 20 U oxytocin or 1 mL saline intravenously. In Trial 2, 51 mares were inseminated with 4 mL extended semen from 1 of 4 stallions (1 fertile and 1 subfertile male used in Trial 1, and 2 additional fertile males). Immediately after insemination, and again 30 min later, mares were administered either 5 U oxytocin or 0.25 mL saline intramuscularly. To test for effects of treatment with oxytocin and for the interaction between semen quality and treatment, a generalized linear mixed regression model was used that accounted for the split-plot design (treatment within stallions), the random effect of stallion, the fixed effect of semen quality, the binary outcome of a single breeding trial, and the varying number of trials per stallion/treatment groups. Three treatment protocols or regimens were used: placebo, 5 U oxytocin injected twice intramuscularly, and 20 units oxytocin injected twice intravenously. Semen was classified as high (fertile stallions) or low (subfertile stallions) quality. No interaction between semen quality and treatment was detected (P > 0.10). The pregnancy rate of mares treated with oxytocin immediately after insemination was 30% (15/50) compared with 50% (25/50) for mares treated with saline immediately after breeding. Administration of oxytocin did not affect pregnancy rates (P > 0.10).

Use of prostaglandin E2 to ripen the cervix of the mare prior to induction of parturition

Eleven light-breed pregnant mares (335 to 347 d gestaton) were used to evaluate the use of prostaglandin E2 as a cervical ripening agent prior to induction of parturition during the months of April and May. Six hours prior to induction, each mare's cervix was examined per vagina for softness and dilation. Each mare was then assigned to 1 of 2 treatment groups: Group PGE mares (n = 7) received 2.0 to 2.5 mg prostaglandin E2 deposited intracervically; Group SAL mares (n = 4) received 0.5 mL of sterile NaCl deposited intracervically. Six hours later, the mares were readied for parturition by wrapping the tail, scrubbing and rinsing the perineum and udder, and examining the cervix as previously described. Each mare was then administered 15 U, i.v. oxytocin at 15-min intervals until the chorioallantois ruptured. Intervals from initial oxytocin injection until rupture of the chorioallantois, from initial oxytocin injection until delivery of the foal, from delivery of the foal until the foal stood unassisted, and from delivery of the foal until the foal suckled were recorded. Mean cervical dilation immediately prior to induction of parturition tended to be greater in Group PGE mares (3.9 +/- 1.7 cm) than in Group SAL mares (1.9 +/- 1.9 cm; P = 0.10). Mean change in cervical dilation over the 6-h period prior to induction (3.4 +/- 1.9 cm vs 1.5 +/- 2.1 cm), mean number of injections of oxytocin required until the chorioallantois ruptured (1.9 +/- 0.7 vs 2.5 +/- 1.0), and mean intervals from initial injection of oxytocin to rupture of the chorioallantois (20 +/- 10 min vs 28 +/- 19 min) and delivery of the foal (28 +/- 7 min vs 34 +/- 22 min) were not different between Group PGE and SAL mares, respectively (P > 0.10). The proportion of foals that stood within 1 h of birth also did not differ between Group PGE foals (6/7; 86%) and Group SAL foals (3/4; 75%; Chi-square = 0.17; P > 0.10). The proportion of foals that nursed within 2 h of birth was higher in Group PGE foals (6/7; 86%) than in Group SAL foals (1/4; 25%; Chi-square = 4.02; P < 0.05). Premature separation requiring manual rupture of the chorioallantois at the vulvar labia occurred in 1 Group PGE mare (cervical dilation of 1.5 cm at time of induction) and 1 Group SAL mare (cervix closed and firm at time of induction). Foals born from the 2 mares with premature placental separation had the longest intervals from initial oxytocin injection to delivery, delivery to ability to stand unassisted, and delivery to suckling within their respective treatment groups. In summary, it appears that cervical ripening prior to induction of parturition favors shorter deliveries and foal vigor. Intracervical administration of prostaglandin E2 may prove useful for ripening the cervix of the mare prior to induction of parturition. Further studies are indicated to determine optimal dosage and method of administration of prostaglandin E2.

Laparoscopic vs open appendectomy. Prospective randomized study of outcomes

OBJECTIVE

To compare open appendectomy (OA) with laparoscopic appendectomy (LA) for length of the operation, complications, postoperative pain control, length of hospitalization, postdischarge recovery time, and hospital charges.

DESIGN

Prospective randomized clinical trial of patients with acute appendicitis.

SETTING

Tertiary care, urban teaching hospital.

PATIENTS

A population-based sample of patients (aged > or = 12 years; weight, > 49.7 kg) admitted to a surgical teaching service with a clinical diagnosis of acute appendicitis. Patients were prospectively randomized to either OA or LA during a 20-month period (from April 1, 1994, to December 31, 1995). Fifty-seven patients were initially enrolled in the study; 7 did not complete the study because of a protocol violation. All remaining patients completed the study, including postdischarge follow-up.

INTERVENTIONS

Two (7.4%) of the 27 patients in the LA group required conversion to OA because of technical difficulties. One patient (in the OA group) underwent a second surgical procedure for drainage of a pelvic abscess. Three patients (in the LA group) required second surgical procedures. For analysis, no crossovers were allowed and all patients remained in their originally randomized group.

MAIN OUTCOME MEASURES

Length of the operation, intraoperative and postoperative complications, postoperative pain control, length of hospitalization, postdischarge recovery time, and hospital charges.

RESULTS

Fifty patients (19 women and 31 men) were examined. Twenty-seven patients underwent LA, 2 requiring conversion to an OA. Twenty-three patients underwent an OA. Patient demographics were similar between groups. Statistical differences between the 2 groups were found for (1) length of the operation (median, 81.7 vs 66.8 minutes, LA vs OA groups: P < .002), (2) operating room charges (median, $3191 vs $1514, LA vs OA group; P < .001), and (3) total hospital charges (median, $5430 vs $3673, LA vs OA group; P < .001). No statistical differences between the 2 groups were found for (1) length of hospitalization (median, 1.1 vs 1.2 days, LA vs OA group), (2) pain control (mean, 4 vs 3.7 of 10 [0 indicates least pain; 10, most pain], LA vs OA group), (3) recovery time (time necessary before returning to work or school) (median, 14.0 days for both groups), and (4) complications (5 vs 1, LA vs OA group).

CONCLUSIONS

Laparoscopic appendectomies and OAs are comparable for complications, postoperative pain control, length of hospitalization, and recovery time. Patients who underwent an OA had a shorter operative time and lower operating room and hospital charges. Laparoscopic appendectomy does not offer any proved benefits compared with the open approach for the routine patient with acute appendicitis.

Biodegradable estradiol microspheres do not affect uterine involution or characteristics of postpartum estrus in mares

Quarterhorse mares were used to investigate effects of estradiol-17beta on uterine involution, duration of estrus, interval to ovulation, and fertility achieved by breeding on the first postpartum estrus. On the day of foaling, mares were injected with biodegradable poly (DL-lactide) microspheres containing either 100 mg estradiol-17beta (25 mares) or no drug (27 mares). The treatment period was considered to last for 12 to 15 d. Estrus was determined by teasing mares (n=16) with a stallion. Ovulation was detected by transrectal ultrasonographic examination of ovaries (n=48). On Days 6, 11 and 16 post partum, transrectal ultrasonography was used to measure cross-sectional diameters of the uterine body, uterine horns, and fluid within the uterine lumen (n=28). Uteri were swabbed for bacteriologic culture, and uterine biopsies were obtained from the previously gravid uterine horn on Days 11 and 16 post partum, for assessment of endometritis and morphometric analysis of endometrial histioarchitecture (n=19). Twenty-two mares were bred on foal-heat, and pregnancy was determined by transrectal ultrasonography on 14 to 16 and 30 to 35 d after breeding. With only one exception (diameter of previously gravid uterine horn on Day 11), mean values for all measures of uterine involution did not differ between treatment groups (P > 0.05). No differences were detected between treatment group means for length of estrus or interval to ovulation (P > 0.05). No differences were detected between treatment group liklihoods for recovery of potential bacterial pathogens, presence of endometritis, or presence of intrauterine fluid at 11 or 16 d post partum (P > 0.05). Pregnancy rate of mares treated with estradiol (5 11 ; 45%) was not different from that of control mares (9 11 ; 82%; P > 0.05). Estradiol treatment did not hasten uterine involution, increase duration of estrus, delay ovulation, or increase fertility in these postpartum mares.

The acuity card procedure: a rapid test of infant acuity

Forced-choice preferential looking (FPL) and operant preferential looking (OPL) procedures for testing infant acuity typically require 15-45 min to derive an acuity estimate. This article presents a new acuity assessment technique ("acuity cards") that combines FPL/OPL stimuli with an observer's subjective assessment of an infant's looking behavior. The infant is shown a series of gray cards that contain grating targets of various spatial frequencies. An observer watches the eye movement patterns and behavior of the infant and judges whether the infant can or cannot see the grating on each card in the series. Acuity is estimated as the highest spatial frequency that the observer judges the infant to be able to see. With this technique, the binocular acuity of normal infants can be estimated with reasonable accuracy in the laboratory setting in 3-5 min.

Tritan discriminations by 1- and 2-month-old human infants

The capacity of 1- and 2-month-old infants to make a tritan discrimination between a 4 degree, 416 nm test field and a 547 nm surround was tested by means of the forced-choice preferential looking technique. Most of the 2-month-olds and the other 1-month-olds made the tritan discrimination and must therefore have functional SWS cones. Most of the youngest 1-month-olds failed to make the tritan discrimination and therefore either do not encode or do not preserve the information ordinarily encoded by SWS cones. The implications of these data and the prior data of Hamer et al. [Vision Res. 22, 575-587 (1982)] are discussed in relation to color theory.

Temporal sensitivities related to color theory

Sensitivities of color-normal observers to temporal variations in stimulus luminance and chromaticity were measured for sine-wave stimuli between 1.5 and 20 Hz. Clear differences were found in observers' sensitivities to isochromatic luminance variations and to isoluminous chromaticity variations for wavelength pairs selected to test temporal discriminability along the red-green and yellow-blue dimensions, respectively. Despite interobserver differences in individual red-green functions, a given observer's sensitivity could be described by a single curve shape specific to that observer. Overall sensitivity for yellow-blue was less than that for red-green for all observers. Differences in curve shape between red-green and yellow-blue functions are found for individual observers, but group averages reveal that the differences are not systematic. Red-green temporal sensitivity is largely unaffected by adapting backgrounds in red-green equilibrium but is attenuated at low frequencies by nonequilibrium backgrounds of the same luminance. Isochromatic luminance sensitivity is largely independent of our adapting backgrounds, but heterochromatic luminance modulation functions undergo expected changes in form.