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J M Vázquez

Publications and source records attributed to J M Vázquez.

At least 19 recordsLinked to original sources
PubMed2006

Challenges in pig artificial insemination.

Semen extended in a liquid state, together with conventional artificial insemination (AI), is the sole sperm technology used by the pig industry. Sperm technologies known for many years, such as cryopreservation, and others developed during recent years, such as sperm sexing, have not yet been integrated into commercial use. Moreover, there has recently been an explosion of new technologies, such as sperm mediated gene transfer or encapsulated spermatozoa which need additional supportive techniques before they can be economically applied to pig breeding. The speed with which the aforementioned sperm technologies are accepted and utilized by the pig industry depends on the availability of efficient insemination procedures. Therefore, AI is entering a new dimension where it will be converted into a tool for the efficient application of current and new sperm technologies. Some new insemination procedures have been recently developed. This review examines the suitability of available insemination procedures for the efficient application of current, emergent and future sperm technology to the pig industry.

Animals↗
PubMed2006

Factors influencing boar sperm cryosurvival.

Optimal sperm cryopreservation is a prerequisite for the sustainable commercial application of frozen-thawed boar semen for AI. Three experiments were performed to identify factors influencing variability of postthaw sperm survival among 464 boar ejaculates. Sperm-rich ejaculate fractions were cryopre-served using a standard freezing-thawing procedure for 0.5-mL plastic straws and computer-controlled freezing equipment. Postthaw sperm motility (assessed with a computer-assisted semen analysis system) and viability (simultaneously probed by flow cytometry analysis after triple-fluorescent stain), evaluated 30 and 150 min postthaw, were used to estimate the success of cryopreservation. In the first experiment, 168 unselected ejaculates (1 ejaculate/boar), from boars of 6 breeds with a wide age range (8 to 48 mo), were cryopreserved over a 12-mo period to evaluate the predictive value of boar (breed and age), semen collection, transport variables (season of ejaculate collection, interval between collections, and ejaculate temperature exposure), initial semen traits, and sperm quality before freezing on sperm survival after freezing-thawing. In Exp. 2, 4 ejaculates from each of 29 boars, preselected according to their initial semen traits and sperm quality before freezing, were collected and frozen over a 6-mo period to evaluate the influence of interboar and intraboar ejaculate variability in the survival of sperm after cryopreservation. In Exp. 3, 12 ejaculates preselected as for Exp. 2, from each of 15 boars with known good sperm cryosurvival, were collected and frozen over a 12-mo period to estimate the sustainability of sperm cryosurvival between ejaculates over time. Boar and semen collection and transport variables were not predictive of sperm cryosurvival among ejaculates. Initial semen traits and sperm quality variables observed before freezing explained 23.2 and 10.9%, respectively, of the variation in postthaw sperm motility and viability. However, more that 70% of total variance observed in postthaw sperm quality variables among ejaculates was explained by boar. This indicates that boar is the most important (P < 0.001) factor explaining the variability among ejaculates in sperm cryosurvival, with most (14 of the 15 boars in Exp. 3) showing consistent (P > 0.05) sperm cryosurvival over time.

Animals↗
PubMed2006

Strategies to improve the fertility of frozen-thawed boar semen for artificial insemination.

Although cryopreservation of boar semen for artificial insemination (AI) was developed 35 years ago, cryopreservation conditions and AI strategies are still considered sub-optimal. AI with excessive numbers of frozen-thawed sperm (5-6 x 10(9) cells), still does not achieve fertility levels similar to AI using liquid semen because of reduced sperm survival. Frozen-thawed (FT) spermatozoa have therefore not been the preferred option for commercial breeding programmes. However, substantial progress has been made regarding boar sperm cryopreservation. Adjustment of cooling and re-warming rates to biophysical properties of boar spermatozoa, new sperm package systems and the achievement of accurately consistent freezing of large numbers of samples using programmable freezers have contributed to post-thaw survival rates above 50%, a threshold similar to that used for bull AI-semen. Moreover, these post-thaw sperm survival rates are consistent within a large population of boars selected for sperm freezability potential, as occurs with AI-bull sires. When such post-thaw boar semen is deposited intra-utero, acceptable fertility (in terms of farrowing rates and litter size) is obtained. Currently, the most effective application of FT-semen for AI is achieved using deep uterine-AI (DUI) which allows placement of a minimal semen dose (in volume 0.5 to 10 mL and sperm number 0.5 to 1 x 10(9) total spermatozoa) into the anterior 1/3 of one uterine horn, with levels of fertility close to AI with liquid semen. However, owing to their shorter life span, FT-boar spermatozoa require an AI-to-ovulation interval not longer than 4-6 h, making peri-ovulatory AI a pre-requisite to obtain the highest possible fertility. Spontaneous ovulation most often occurs when two-thirds of oestrus has passed. Estimation of the duration of oestrus, taking into account the weaning-to-oestrus interval, is helpful when establishing appropriate AI-schedules. However, as the length of oestrus varies within and between farms, different AI strategies should be established a priori. The development of bio-sensors for spontaneous ovulation will widen the use of AI with frozen-thawed frozen semen.

Animals↗
PubMed2005

Does multivariate analysis of post-thaw sperm characteristics accurately estimate in vitro fertility of boar individual ejaculates?

The objective of this study was to determine if a multivariate pattern analysis of frozen-thawed sperm characteristics of boar semen of unknown fertility, thus identifying groups of ejaculates as "good" or "bad" freezers, would estimate their fertilizing potential in an in vitro embryo production (IVP) system. Frozen-thawed spermatozoa from a single ejaculate collected from 46 boars were evaluated for sperm motility and kinematic patterns, for sperm viability and for early changes in sperm membrane stability. All data generated were used for a multivariate pattern analysis (PATN; CSIRO, Canberra, Australia) which objectively classified all ejaculates within a data set in to one of two groups, categorised as "good" (n = 25) or "bad" (n = 21) according with their freezability. In vitro matured oocytes were exposed to 2000 or 4000 frozen-thawed spermatozoa per oocyte for 6h and then cultured in embryo culture medium for either 6h (assurance of fertilization) or 7 days (to collect data on embryo development). Rates of sperm oocyte penetration and of embryo development significantly (p < 0.05) increased in a sperm:oocyte ratio-dependent manner. A similar pattern was observed when sperm characteristics were grouped. Indeed, ejaculates classified as "good" showed significantly (p < 0.05) higher rates of oocyte penetration, cleavage and of blastocyst formation than those classified as "bad". However, variation was still present among individuals (ejaculates, boars) in their ability to produce blastocysts in vitro. It is therefore concluded that despite the presence of a relationship for ejaculates with good semen quality post-thaw (thus grouped as "good") to higher IVP-results, the presence of individual variation does not allow for an accurate estimation of in vitro fertility based solely on the frozen-thawed semen quality parameters of a single ejaculate from a given boar.

Analysis of Variance↗
PubMed2005

Piglets born after non-surgical deep intrauterine transfer of vitrified blastocysts in gilts.

The aims of this study were: (1) to evaluate the effect of the number of previous estrus of recipient gilts on effectiveness of intrauterine insertion of a flexible catheter designed for non-surgical deep intrauterine catheterization during diestrus in pigs; and (2) to determine the farrowing rate and the litter size after non-surgical deep intrauterine embryo transfer (ET) of porcine blastocysts vitrified by the open pulled straw (OPS) method. In experiment 1, 27 large white hyperprolific gilts (LWh) with 2-6 previous estrus were used. Intrauterine insertions of the flexible catheter were carried out at day 5.5-6 of the estrous cycle (D0=onset of estrus). During insertions, no or only moderate reactions were observed in 88.9% of gilts and was not related (P >0.05) to the number of estrus prior to the insertion periods. The number of the estrus had a significant effect (P <0.05) on the difficulties found during the procedure. In the 100% of gilts with two estrus (N=6) it was not possible to insert the flexible catheter through the cervix. In gilts with three or more estrus, it was possible to pass the cervix and to progress along a uterine horn in 80.9% of the cases. In 86.7% of the gilts, the tip of the flexible catheter achieved the second or third quarter of the uterine horn. In experiment 2, following non-surgical deep intrauterine transfer of 20 vitrified/warmed blastocysts, 9 Meishan recipients (42.9%) farrowed an average of 5.4 +/- 0.8 piglets (range 3-9) of which 0.6 +/- 0.3 piglets (range 0-2) were born dead. In conclusion, this study shows that it is possible to obtain birth of piglets following non-surgical deep intrauterine embryo transfer (ET) of vitrified/warmed blastocysts. Non-surgical deep intrauterine ET and OPS vitrification methods are promising procedures to be used together for the introduction of new genetic material in a farm.

Animals↗
PubMed2005

Anatomy of the cranioencephalic structures of the camel (Camelus dromedarius L.) by imaging techniques: a magnetic resonance imaging study.

The objective of this study was to define the anatomy of the cranioencephalic structures and associated formations in camel using magnetic resonance imaging (MRI). MR images were acquired in sagittal, transverse and oblique dorsal planes, using spin-echo techniques, a magnet of 1.5 T and a standard human body coil. MR images were compared with corresponding frozen cross-sections of the head. Different anatomic structures were identified and labelled at each level. The resulting images provided excellent soft tissue contrast and anatomic detail of the brain and associated structures of the camel head. Annotated MR images from this study are intended to be a reference for clinical imaging studies of the head of the dromedary camel.

Animals↗
PubMed2005

Normal anatomical imaging of the thorax in three dogs: computed tomography and macroscopic cross sections with vascular injection.

The purpose of this study was to provide a new reference for interpretation of the normal anatomy of the canine thorax as imaged using computed tomography (CT). Three mature dogs, all mixed breed males, were used for this study. The dogs were sedated, anaesthetized and maintained in sternal recumbency. CT study from the first to the thirteen thoracic vertebra was performed with a TOSHIBA 600 HQ scanner (third generation equipment). Dogs were killed and vascular-injection technique was performed: red latex and blue latex filled vascular system. Injected dogs were frozen and sectioned with an electric bandsaw, the cuts matched as closely as possible to the CT images. The CT images from this study are intended as a reference for clinical CT imaging studies of the thoracic cavity of the dog and for interpreting lesions of the thorax and associated structures.

Animals↗
PubMed2004

Hoechst 33342 stain and u.v. laser exposure do not induce genotoxic effects in flow-sorted boar spermatozoa.

Sex selection by flow cytometry/cell sorting involves the staining of spermatozoa with Hoechst 33342 in combination with the impact of a u.v. laser beam, two potentially mutagenic agents. A phenotypic and cytogenetic study of lymphocytes of piglets born after insemination with spermatozoa stained with Hoechst 33342 and from piglets obtained from stain-sorted spermatozoa was performed to evaluate the genotoxic effect of Hoechst 33342 staining and u.v. laser irradiation on the offspring. Lymphocytes from piglets born after insemination with unstained spermatozoa, but from the same ejaculate, were used as a control group. Peripheral blood lymphocytes from these piglets were cultured following a standard cell culture protocol. Cells were then collected by centrifugation, subjected to hypotonic solution and fixed and dropped onto slides. Sister chromatid exchanges (SCEs) and chromosome aberrations (CAs: including chromosome and chromatid breaks) per cell were scored in 50-s division metaphase spreads from each donor. Reproductive parameters and litter performance of all inseminations performed were also recorded in all groups. Data were analyzed by ANOVA. No significant increase (P > 0.05) of SCE and CA frequencies were observed in piglets born from stained spermatozoa or from stain-sorted spermatozoa with respect to controls (untreated sperm). The results indicated that no mutagenic effect on spermatozoa, expressed as increases in the incidence of abnormalities in the resulting offspring and also as increases in SCE and CA frequencies on lymphocytes from these individuals, was induced by the staining of boar spermatozoa with Hoechst 33342, nor by combination of staining with laser impact during flow cytometry.

Animals↗
PubMed2003

Influence of follicle size on the penetrability of immature pig oocytes for homologous in vitro penetration assay.

In order to improve the performance of homologous in vitro penetration (hIVP) assays using immature oocytes to assess the penetrating ability of boar sperm, the present study was designed to evaluate the influence of oocyte and follicle size on the penetrability of immature pig oocytes obtained from slaughterhouse ovaries. Nonatretic antral follicles were isolated, measured with a computerized image analysis system and grouped according to their diameter: Group 1 (0.40-0.99 mm), Group 2 (1.00-2.19 mm), Group 3 (2.20-2.79 mm), and Group 4 (2.80-6.50 mm). After sperm coincubation and before penetrability evaluation, the immature oocytes were classified into four size categories according to their diameter excluding zona pellucida: <105, 105-109, 110-114, and > or =115 microm. As regards follicle size, the highest viability and penetrability were obtained with oocytes from follicles >2.20 mm (P>0.05). Regarding oocyte size, significant differences (P<0.05) were observed for all parameters evaluated between oocytes with a diameter above or below 110 microm. However, our results revealed that such differences were due to follicle size rather than oocyte diameter, since oocytes with the same diameter but from different follicle size groups showed different penetration rates. With increasing follicle size, the percentage of penetrated oocytes increased (P<0.05). Finally, our results showed that the greater penetrability of immature oocytes from larger follicles is not due to variations in the thickness of the zona pellucida. There were no significant differences in zona pellucida thickness between oocytes from the four follicular size groups. In summary, these results indicate that follicle size directly affects the penetrability of immature pig oocytes used in hIVP.

Animals↗
PubMed2003

Effect of two thermal regimes on the muscle growth dynamics of sea bass larvae, Dicentrarchus labrax L.

Muscle growth was studied in larvae of sea bass, Dicentrarchus labrax L., reared at two temperatures: real ambient temperature ( congruent with 15 degrees C during vitelline phase and increased gradually) and 19 degrees C from fertilization until the end of larval development. Muscle cellularity, body length and body weight were measured. Early temperature influenced larval development and so, pre-larval phase finished earlier at 19 degrees C than at ambient temperature (4 and 6 days, respectively). Temperature also affected muscle growth such that at hatching and at mouth opening hypertrophy of muscle fibres was greater at 19 degrees C (P < 0.05), whereas hyperplasia was similar in both groups. After 25 days, the cross-sectional area of the white muscle was greater at 19 degrees C (P < 0.05), which was mainly associated with a higher proliferation of new white muscle fibres. At this stage the body length was also higher at 19 degrees C. Metamorphosis finished earlier in fish reared at 19 degrees C (52 days) than at natural temperature (82 days). At this developmental stage body length and cross-sectional area of the myotome were similar in both groups. However, muscle cellularity differed between groups. Thus, hypertrophy of muscle fibres was higher in fish reared at ambient temperature (P < 0.05), whereas proliferation of new muscle fibres was higher at 19 degrees C (P > 0.05).

Animals↗
PubMed2003

Fluorescence in situ hybridization in diluted and flow cytometrically sorted boar spermatozoa using specific DNA direct probes labelled by nick translation.

Successful evaluation of X- and Y-chromosome-bearing sperm separation technology using flow cytometry-cell sorter is of great importance. Fluorescence in situ hybridization (FISH), which allows for the detection of specific nucleic acid sequences on morphologically preserved spermatozoa, is an ideal method for quantitatively and qualitatively assessing the purity of sorted sperm samples. In this study specific pig DNA direct probes for small regions of chromosomes 1 and Y were used. Chromosome 1 was labelled in green and used as internal control to detect a lack of hybridization, whereas chromosome Y was labelled in red. Nick translation was used as the labelling method for the preparation of these probes. Spermatozoa, unsorted and sorted for high and low Y-chromosome purity from ejaculates of five boars, were fixed on slides and two-colour direct FISH was performed for chromosomes 1 and Y. About 500 non-sorted and 200 sorted spermatozoa per sample were scored. The proportion of Y-chromosome-bearing spermatozoa was determined by the presence of a red fluorescent signal on the sperm head and the proportion of X-chromosome-bearing spermatozoa was determined by subtraction. The efficiency of the hybridization procedure was established as near 98% on sorted and unsorted samples. The results of this study confirm that direct FISH using specific pig DNA probes labelled by nick translation provides a useful tool for laboratory validation of sperm separation by flow sorting technology. Moreover, the ease of nick translation and the quality of the fluorescent signal obtained using this method makes this procedure the most appropriate method for labelling pig DNA probes to be used for direct FISH on pig spermatozoa.

Animals↗
PubMed2002

Relationship between antral follicle size, oocyte diameters and nuclear maturation of immature oocytes in pigs.

We designed the present study to examine the possible relationship between oocyte, antral follicle size and the nuclear heterogeneity of immature pig oocytes, in order to study the heterogeneity of oocyte populations in ovaries obtained from slaughterhouses. Previously, we carried out an initial experiment to determine, by histological analysis, the effectiveness of the macroscopic criteria (MC) used to screen atretic and nonatretic antral follicles. We recovered 239 follicles by mechanical dissection, measured them with a computerized image analysis system, and classified them into five size categories according to their diameter (FD): Group 1 (0.40-0.99 mm), Group 2 (1.00-2.19 mm), Group 3 (2.20-2.79 mm), Group 4 (2.80-3.59 mm) and Group 5 (3.60-6.50 mm). In relation to histological analysis, the results showed that MC is an effective method to select atretic and nonatretic antral follicles from 0.40 to 6.50 mm in diameter (overall accuracy was 80.75%, with sensitivity and specificity rates of 79.33 and 82.20%, respectively). In a second experiment, we recovered 454 nonatretic follicles, then measured and classified them as mentioned above. We removed oocytes individually from follicles and measured their size (oocyte diameter without and with zona pellucida, OD and TOD, respectively). Finally, we evaluated the relationship between OD, FD and nuclear maturation of immature oocytes (germinal vesicles (GV) Stages 0, I, II, III and IV; diakinesis, prophase I, and metaphase I). Overall OD was 101.77 +/- 0.65, 109.19 +/- 0.45, 113.55 +/- 0.50, 116.92 +/- 0.46 and 117.13 +/- 0.47 microm (Groups 1, 2, 3, 4, and 5, respectively). Differences in OD between groups were significant (P < 0.01), although from 2.80 to 6.50 mm follicles, the oocytes were not different in size. There was a certain heterogeneity in OD within each follicular group. Although we observed a certain degree of nuclear variability, regardless of FD or OD, the present study showed a clear progression in GV when FD increased from 0.40 to 6.50 mm. A positive correlation (r2 = 0.4248; P > 0.05) was established mainly between the nuclear stage and oocyte diameter.

Animals↗
PubMed2002

[Determination of insulin, leptin and neuropeptide y by radioimmunoanalysis in patients with morbid obesity and anorexia nervosa after therapeutic intervention].

The present study was conducted in order to analyze the relationship existing between leptin, insulin and neuropeptide Y (NPY) levels in massive weight loss and weight recovery. Twenty-three patients with severe obesity, 23 patients with anorexia nervosa and 28 healthy control subjects were studied. Patients with severe obesity underwent a vertical banded gastroplasty followed by an 800 kcal/day diet during 16 weeks, with evaluation taking place before (Body mass index, BMI, 52,1 8 Kg/m2) and after the drastic weight loss (BMI 39,2 6,2 Kg/m2). Patients with anorexia nervosa were treated with nutritional therapy exclusively during 16 weeks, and they were evaluated in the low weight situation (BMI 15,3 1,7 Kg/m2) and after weight recovery (BMI 18,9 2,8 Kg/m2). Normal subjects had a normal BMI from 20 to 27 (average 21,8 2 Kg/m2). BMI, percentage of body fat, and serum levels of leptin, insulin, and NPY, were determined in each patient and normal subjects. In severe obese patients serum leptin and insulin decreased significantly after drastic weight reduction (leptin: from 48,8 19,2 to 24,3 9,8 ng/ml; insulin: from 26,2 10,8 to 18 6 U/ml). In patients with anorexia nervosa serum leptin mean levels were significantly higher after weight recovery (3,7 1,9 vs 9,2 5,1 ng/ml). In subjects with morbid obesity NPY levels decreased after weight loss below those of control group (43,5 16,1 vs 57,3 12,8 pmol/l). On the other hand, patients with anorexia nervosa had NPY levels superior to those of control group. In subjects with anorexia, NPY levels decreased after weight recovery (69,1 16,7 a 59,1 20,3 pmol/l). In the whole population, Leptin and NPY plasma levels were correlated with body fat percentage. Leptin was positively correlated with BMI and body fat percentage in obese and anorectic subjects after weight loss or recovery, respectively. NPY was inversely correlated with body fat percentage in controls and obese subjects before treatment. These data reveal that the concentration of serum leptin and NPY correlates significantly with the total adiposity in subjects with a wide weight range and caloric intake. Leptin plasma levels are proportional to fat stores in patients with severe obesity and anorexia nervosa after drastic weight loss or recovery, respectively. NPY serum levels are negatively correlated with de total body fat in normal weight subjects and obese patients in their initial weight.

Adult↗
PubMed2001

Magnetic resonance imaging of two normal equine brains and their associated structures.

Magnetic resonance images were obtained from two isolated horses' heads. Ten mm thick, T1-weighted images were taken with a 1.5 Tesla magnet and a body coil, and compared with the corresponding frozen cross-sections of the heads, relevant structures being identified and labelled at each level. The images should provide reference material for clinical magnetic imaging studies of horses' heads.

Animals↗
PubMed2001

The histochemical profiles of fibre types in porcine skeletal muscle.

Using a variety of histochemical methods -mATPase staining after alkaline and acid preincubations, NADH-TR and alpha-MGPDH- we have investigated the fibre types in porcine skeletal muscle. The results reveal that four major fibre types -I, IIA, IIB and II*- can be separated histochemically in Longissimus lumborum muscle of Landrace pigs. The histochemical properties of the muscle fibre type II* are very similar to that of type IIX described in other mammals. The existence of IIX fibres in pig muscle has been recently demonstrated by molecular biology techniques and our results validate the use of histochemistry (mATPase) as an easy methodology to differentiate the three fast myosins (type II fibres) in pig muscle.

Adenosine Triphosphatases↗
PubMed2000

Viability and fertility of rabbit spermatozoa diluted in Tris-buffer extenders and stored at 15 degrees C.

Artificial insemination (AI) in rabbits is not extensive in the breeding programs of the rabbit meat industry. A limiting factor is related to the semen preservation. In order to improve the use of AI, two experiments have been conducted to evaluate sperm viability and fertility of rabbit semen chilled and stored at 15 degrees C after dilution in Tris-based extenders. In Experiment 1, pooled semen samples were diluted 1:10 (semen/extender) in four different Tris-based extenders (Tris-citric-glucose (TCG), TES-Tris-glucose (TTG), Tris-citric-fructose (TCF) and TES-Tris-fructose (TTF)) and stored at 15 degrees C. Sperm viability was evaluated at 0, 24, 48, 72 and 96 h following dilution for total sperm motility (TSM), forward progressive motility (FPM), plasma membrane integrity (PMI) and acrosome integrity (NAR). Viability of spermatozoa declined with time of storage (P<0.05), irrespective of the extender used. There were interactions between extender and time of storage (P<0.05) in all viability parameters evaluated. After 96 h of storage, TCG provided the highest sperm viability (P<0.05) and TTG the lowest (P>0.05). In Experiment 2, a field trial was conducted at a commercial farm to evaluate the conception and farrowing rates of rabbit spermatozoa extended in TCG. After synchronization of oestrous and induction of ovulation, 3713 does with different physiological conditions (nulliparous, primiparous, lactating and re-breeding) were inseminated one time (15x10(6) sperm per doses) with semen stored at 0 (n: 1275), 24 (n: 1503) and 48 h (n: 935) at 15 degrees C. Overall conception and farrowing rates were 77.1+/-0.7 and 70.4+/-0.7, respectively, and the mean litter size was 7.6+/-0.1. Fertility results were unaffected by the time of semen storage (P>0.05). Regardless of time of semen storage, fertility results were affected by the physiological conditions of does (P<0.05). Nulliparous and lactating does showed the highest fertility and primiparous the lowest. In summary, these results indicate that Tris-buffer extenders are effective for preserving viability and fertilizing capability of rabbit spermatozoa stored at 15 degrees C.

Acrosome Reaction↗