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Biomedical subjects

W Holtz

Publications and source records attributed to W Holtz.

At least 37 records · Page 2Linked to original sources
PubMed1995

Superovulation of goats with purified pFSH supplemented with defined amounts of pLH.

The superovulatory response of goats treated with purified pFSH supplemented with 30, 40 or 50% pLH was compared. Sixty-four Boer goat does were synchronized by progestagen-containing ear implant, randomly allotted to 3 groups and, beginning 2 d before implant removal, treated with purified pFSH supplemented with 30, 40 or 50% pLH. Each animal received 16 Armour Units of pFSH administered in 6 descending doses at 12-h intervals. Along with the last 2 injections, the does received 5 mg PGF(2alpha). Embryos were flushed either surgically or after slaughter on Day 5 or 6 after the last day of standing estrus. The percentage of animals responding to treatment was not different among groups treated with pFSH supplemented with 30, 40 or 50% pLH (76, 71 and 63%, respectively). The corresponding data for number of ovulations was 11.3 +/- 1.6, 16.3 +/- 1.8 and 16.4 +/- 2.6, for number of ova and embryos recovered 8.1 +/- 1.9, 12.0 +/- 1.5 and 13.5 +/- 2.9 and for number of transferable embryos 6.6 +/- 1.9, 9.1 +/- 1.5 and 7.1 +/- 2.1 (x +/- SEM). Results confirm the earlier finding of a good response of goats to pFSH preparations with a high FSH:LH ratio, and, although group differences were statistically nonsignificant (P > 0.05), they suggest that supplementation with approximately 40% pLH may be close to the optimum.

Journal Article↗
PubMed1995

In vitro culture of goat morulae to blastocysts before freezing.

The results of transfer of frozen-thawed caprine embryos that were collected either as blastocysts or morulae and cultured to the blastocyst stage prior to freezing were compared. After thawing, the embryos collected as blastocysts appeared to be of marginally better quality than those that had been cultured from morulae (89 vs 72% rated as good; P > 0.05). The transfer of 24 frozen-thawed embryos collected as blastocysts to 12 recipients resulted in a pregnancy rate of 83% (10/12) and an embryo survival rate of 67%. Corresponding results for frozen-thawed blastocysts that had been cultured from morulae and were transferred to 11 recipients were 54% (6/11) and 41%, respectively. Since an earlier investigation had shown that the transfer of frozen caprine morulae yields very poor results, in our laboratory all morulae are now cultured to the blastocyst stage before being cryopreserved.

Journal Article↗
PubMed1994

Splitting of porcine embryos at the four-cell or morula stage.

Porcine embryos obtained from estrus-induced prepuberal gilts were split at the 4-cell and morula stage. The in vitro development of the demi-embryos was compared with that of intact control embryos. The intact control embryos developed according to expectation. The in vitro survival of the demi-embryos was inferior to that of the respective controls. The splitting of 4-cell embryos was easier to accomplish and more efficient than the splitting of morulae. The in vitro development of the 4-cell embryos was also slightly better, although this difference was not significant. In vitro development of demi-embryos originating from morulae split at room temperature was slightly although nonsignificantly inferior to that of demi-embryos from morulae split on a warming stage at 37 degrees C. Between 14 and 18 demi-embryos were transferred to synchronous recipient gilts after 24 to 48 h of culture. Of 3 gilts receiving split 4-cell embryos, 1 gilt aborted 2 normal fetuses on Day 90 of pregnancy and 1 carried a single piglet to term. Of the 4 gilts receiving split morulae, 1 gilt had 4 normal and 3 degenerated fetuses upon slaughter on Day 35 of pregnancy.

Journal Article↗
PubMed1994

Effect of glycerolization procedure and removal of seminal plasma on post-thaw survival and got-release from Boer goat spermatozoa.

Forty ejaculates (20 for each of 2 experiments) were collected from 4 Boer goat bucks at weekly intervals to study the effect of glycerolization procedure and removal of seminal plasma on progressive motility, percent live spermatozoa and release of glutamic oxaloacetic transaminase (GOT) before and after the freezing of semen. Stepwise glycerolization at 37 degrees C gave higher progressive motility and percentage of live spermatozoa both before freezing and after thawing than one-step glycerolization at 37 degrees C or stepwise extension with glycerol being added after cooling to 5 degrees C. The GOT-release was reduced before freezing and after thawing of semen with stepwise glycerolization (P<0.05). Progressive motility and the percentage of live spermatozoa were higher (P<0.05) after the freezing of whole semen than in washed spermatozoa. The concentration of GOT in the extra-cellular fluid was lower in washed spermatozoa prior to freezing (P<0,05); but after thawing, the washed spermatozoa released more GOT than spermatozoa in whole semen. Removal of seminal plasma prior to freezing spermatozoa in an extender containing egg yolk had an unfavorable effect on their post-thaw motility and integrity.

Journal Article↗
PubMed1994

Effects of photoperiod and slow-release preparations of bromocryptine and melatonin on reproductive activity and prolactin secretion in female goats.

The present study was conducted to investigate seasonal reproductive patterns in a Boer Goat x German Fawn cross and ways to modulate these patterns by injecting slow-release bromocryptine and melatonin preparations. Twenty does were exposed to a light program of alternating periods of 90 long days (LD) followed by 100 short days (SD) twice in succession (LD1, SD1, LD2, SD2). At the beginning of LD2, does were treated as follows: vehicle injection (CTR, n = 7), slow-release bromocryptine (BCR, n = 6), or slow-release melatonin (MLT, n = 7). Blood samples were collected twice weekly, and from October 5 to December 14, 1989, weekly, to be analyzed for progesterone, prolactin, and melatonin. Long days inhibited cyclicity, and short days stimulated it. Prolactin was increased during long days and decreased during short days. High ambient temperature resulted in increased prolactin concentrations. Under long photoperiod, long-acting BCR suppressed prolactin secretion for 68 d, and the estrous season was extended compared with CTR. Under long photoperiod, long-acting MLT increased serum melatonin for 96 d, suppressed prolactin concentration, and substantially lengthened the period of cyclicity compared with the CTR- and BCR-treated groups. The resumption of cyclicity during the subsequent short day period occurred later in MLT- than in CTR- and BCR-treated groups. In conclusion, we modulated the day length-controlled seasonal cyclicity of goats by treating them with injectable slow-release preparations of BCR and MLT, the latter being more effective.

Animals↗
PubMed1993

Enzyme immunoassay for the determination of bovine growth hormone using avidin-biotin-peroxidase complexes.

The development of a competitive enzyme immunoassay for bovine growth hormone (bGH) is described. Antiserum, raised in rabbits and diluted 1/250,000, was preincubated with samples and free antibodies from the reaction mixture were immobilized using a microtiter plates coated with bGH. Bound antibodies remaining from the preincubation were visualized using a biotinylated second antibody as a bridge for subsequent amplification by an avidin-biotin-peroxidase complex. The measuring range was between 0.5 and 100 ng/ml. Cross-reactivity with other pituitary hormones was < 0.1%. The intra- and interassay coefficients of variations were 8.1 and 12.7%, respectively, and the recovery of added bGH was 110%. To validate the assay, two bull calves were treated with bGH-releasing factor. The response showed that there was an immediate rise in immunoreactive bGH which peaked after 5 and 15 min at 200 ng/ml and 60 ng/ml, respectively. This enzyme immunoassay is an economic and sensitive alternative to the established radioimmunoassay, and the first competitive enzyme immunoassay described for bGH.

Animals↗
PubMed1993

Transfer of split goat embryos without zonae pellucidae either fresh or after freezing.

Embryos in the morula to blastocyst stage were collected from superovulated goats either surgically or after slaughter. Embryos with good or fair morphology were bisected with a microblade without the aid of a holding pipette or other microinstruments. Of 103 morulae and 77 blastocysts that were split, 200 (97%) and 151 (98%) demi-embryos, respectively, with no major morphological aberrations were obtained. Zona-free demi-embryos derived from blastocysts were incubated in vitro for 2 h, and those derived from morulae for 24 h so that they would reach the blastocyst stage. Demi-embryos were transferred either fresh or after freezing and thawing. After 2 h of incubation, a significantly higher proportion of zona-free demi-embryos derived from blastocysts were of good quality than were zona-free demi- embryos derived from morulae (75 vs 45%). Seventy-six percent of zona-free demi-embryos derived from morulae developed to the blastocyst stage after 24 h in vitro. The quality of the embryos before splitting had a significant effect on the development of the demi-embryos in vitro. Transfer of 11 pairs of zona-free demi-embryos resulted in the birth of five twin and three singleton kids. Transfer of 11 pairs of demi-embryos frozen-thawed without zonae pellucidae resulted in the delivery of two singleton kids.

Animals↗
PubMed1992

The effect of zwitterion buffers on the freezability of Boer goat semen.

Twenty semen samples with mass activity greater than +3 were collected from six healthy, mature Boer goat bucks. Each ejaculate was divided into four equal parts and extended at 37 degrees C in Tris, Test, Tes and Bes buffers containing egg yolk and glycerol. Semen was placed into medium size French strawsand after 2 hours of equilibration at 5 degrees C, frozen in the vapour phase and stored in liquid nitrogen for 7 days at -196 degrees C. Progressive motility, the number of live spermatozoa and glutamic oxaloacetic transaminase (GOT) release were studied after the initial extension, after equilibration and after 15 minutes and 7 days of freezing of semen. Semen samples when extended with Tris yolk glycerol showed significantly (P<0.01) higher progressive motility and live spermatozoa than when extended with the other zwitterion buffer-based extenders. The change of extenders did not influence the release of GOT at various stages of freezing of semen (P>0.05).

Journal Article↗
PubMed1992

Effects of parity and synchronization of donors by an oral progestogen on embryo transfer in swine.

The aim of this study was to establish whether the quantity or quality of embryos collected is affected by 1) the reproductive status of donors (nulliparous gilts vs parous sows); 2) pretreatment of donors with Oxolven. Embryos were collected from gilts (n=38) and from weaned sows (n=35). Approximately half of each group (gilts and sows) had been subjected to oral treatment with the progestogenic 19-nortestosterone derivative Oxolven for 14 to 21 days. After induction of estrus with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) and following artificial insemination, the embryos were recovered surgically. The ovulation rate of donors averaged 21.6, with no significant difference among groups. Most of the ova and embryos collected were at the 4-cell stage (53%). There was a high incidence of uncleaved ova (28%) in both groups of animals. This was particularly so in gilts, both the Oxolven-treated and controls (35 and 32%). The incidence of uncleaved ova was lower, however, in Oxolven-treated (29%) and control sows (14%). Embryos at the 4- to 8-cell stage were transferred to synchronous recipient gilts. Transfer results, expressed by the survival of transferred embryos, were not significantly affected by the progestogen treatment (30% for Oxolven treatment vs 34% for the controls) or by the reproductive status of the donors (33% for gilts vs 28% for sows).

Journal Article↗
PubMed1992

Characterization of four genes encoding basic proteins of the porcine spermatid nucleus and close linkage of three of them.

Protamines and transition proteins (TNP) play a major role during spermatogenesis and spermatid differentiation. By screening a porcine genomic library with the corresponding cDNAs, we isolated the genomic clones for porcine protamines 1 and 2 as well as for transition proteins 1 and 2. Analysis and comparison of exon-intron structure, 5' and 3' untranslated regions and transcription start points revealed features common to their counterparts in other mammals. In contrast to TNP2 the gene for TNP1 is well conserved among species, indicating a non species-specific function in the chromatin condensation of the spermatid nucleus. Furthermore, Southern blot hybridization of digested phage DNA demonstrated close linkage between both protamine genes and the gene for transition protein 2 in a 13-kb stretch of DNA. Our observations support the hypothesis that these genes may have evolved by gene duplication.

Amino Acid Sequence↗
PubMed1991

Determination of secretion rates of estradiol, progesterone, oxytocin, and angiotensin II from tertiary follicles and freshly formed corpora lutea in freely moving sows.

Two days before ovulation ovarian follicles of sows were implanted with microdialysis systems (MDS) which function like artificial capillaries with exteriorized inlets and outlets. Steroid hormones and paracrine acting factors such as oxytocin (OXT) and angiotensin II (AII) diffuse from ovarian tissue into the fluid, which is pumped through the MDS and collected in fractions. This allows determination of dynamic changes of estradiol (E2), progesterone (P), OXT, and AII secretion during the pre-, peri-, and postovulatory periods in freely moving sows. More than 80% of such implanted follicles ovulate and form competent corpora lutea (CL) allowing continuation of experimentation during the early luteal phase. Follicular E2 release increases before ovulation and decreases with increasing blood LH concentrations. Twenty to 30 h after beginning of the preovulatory LH surge P secretion increases gradually. Both peptides OXT and AII are released episodically by the preovulatory follicle. During the time of decreased E2 and not yet increased P secretion, i.e. during the periovulatory period, mean AII secretion was highest in comparison to the late follicular and early luteal phase. E2 remains measurable during the early luteal phase. OXT and AII were also topically applied into the follicular wall and after ovulation into the CL. AII had no effect on steroidogenesis of both structures. Although OXT was ineffective in the follicle, in young CL it stimulated P secretion. These results indicate that the MDS can be used to study late follicular and early luteal steroid and peptide secretion. The function of OXT and AII in the follicle remains obscure, whereas OXT has a luteotropic effect in young porcine CL.

Angiotensin II↗
PubMed1991

Transfer of porcine embryos after 3 days of in vitro culture.

Two experiments were conducted to determine the viability of porcine embryos transferred after long-term in vitro culture. In Exp. 1, four-cell embryos were kept in culture for 120 h. Embryos that were exposed to fresh culture medium every 12 h survived better than embryos kept in the same medium throughout the culture period. In Exp. 2, four- and eight-cell embryos were cultured in vitro for 72 h before transfer to estrus-induced recipient gilts. Each gilt received, on average, 19 embryos. If recipients were synchronous with donors 3/32 (9%) recipients remained pregnant with an average of 4.0 +/- .6 viable young. If the sexual cycle of the recipients was 24 h behind that of the donors the pregnancy rate was 18/34 (53%) with 4.4 +/- .5 viable young. Average embryo survival rate for the two groups was 1.8 and 12.5%, respectively. A 24-hourly medium replacement during the in vitro culture period had no significant effect on transfer results. When transferring freshly collected blastocysts, pregnancy rate, number of viable young and survival rate of embryos were 6/10 (60%), 7.8 +/- 1.4, and 23.9% for synchronous recipients and 7/10 (70%), 9.3 +/- 1.8, and 32.9% for asynchronous recipients, respectively. Recipients with very high plasma progesterone levels or numerous follicular cysts at the time of transfer were less likely to remain pregnant than others.

Animals↗
PubMed1990

Release and effects of oxytocin on estradiol and progesterone secretion in porcine corpora lutea as measured by an in vivo microdialysis system.

Individual corpora lutea (CL) of Göttinger miniature pigs were implanted with an in vivo microdialysis system. This system functions like an artificial capillary, allowing diffusion of intraluteally secreted substances into the lumen of the dialysis system and administration of hormones into individual CL and simultaneous measurement of the response. After surgery the sows are fully awake and unrestrained. In the present study the in vivo release rates and secretion dynamics of progesterone (P) and oxytocin (OXT) were investigated. The dialysis system was implanted at day 2-4 of the estrous cycle, and dialysis experiments were performed throughout the next 3 days. Fractions were collected at 30 min intervals, and the concentrations of P and OXT were measured by RIA. Three major observations were made: Spontaneous intraluteal secretion of P and OXT occurred in a pulsatile manner. OXT secretion episodes in individual CL often coincide, indicating a simultaneous release from many CL of one ovary but also from the CL located in the contralateral ovary. OXT episodes also often coincide with P pulses; statistical evaluation revealed a significant correlation between P and OXT secretion. Intraluteal application of OXT stimulated luteal P and estradiol (E2) release in a dose-dependent manner. E2 added to the perfusates was also stimulatory to P release. The stimulation of P release by OXT could be antagonized by prior treatment of the CL with tamoxifen. We demonstrate for the first time in vivo the secretion of OXT from porcine CL. The microdialysis system enabled us to collect samples at the site of steroid and peptide release, i.e. within the intact luteal tissue. Our results suggest a stimulatory effect of OXT on P release from young and middle-aged CL and are in marked contrast to the previously demonstrated inhibitory effect of OXT on P release when luteal cells were cultured in vitro. A possible explanation for this apparent discrepancy is that OXT stimulates intraluteal release of E2, which is a powerful P releasing hormone, overcoming the direct inhibitory effect of OXT. This suggestion is substantiated by the observation that E2, when added to the perfusion medium, indeed stimulated P release.

Animals↗
PubMed1990

Control of prostaglandin-induced parturition in sows by injection of the beta-adrenergic blocking agent carazolol or carazolol and oxytocin.

Although parturition commonly is induced in swine with prostaglandin F2 alpha or one of its analogs, variation in response to the treatment is large. The purpose of this investigation was to more precisely terminate parturition. Two experiments were conducted. Sows all received prostaglandin analog followed, 20 h later, by different doses of the beta-adrenergic blocking agent carazolol and(or) oxytocin. Treatment with 3 mg of carazolol alone caused parturition to commence within 2.6 +/- .23 (SEM) h after injection. Parturition was complete in 2.0 +/- .13 h and proceeded smoothly without the necessity of manual assistance. Adding 2.5 I.U. of oxytocin to the 3 mg of carazolol speeded the onset of labor (1.7 +/- .17 h). However, in some cases parturition was interrupted and the time passing between the birth of the first and the last piglet was prolonged to 2.5 +/- .28 h. We conclude that by applying carazolol 20 h after a prostaglandin analog, parturition in swine may be terminated very effectively.

Adrenergic beta-Antagonists↗
PubMed1990

Survival of pig embryos flushed from the reproductive tract immediately or two hours after slaughter of donors.

Four- to eight-cell embryos were collected from genital tracts of slaughtered gilts. Prepuberal donors were synchronized and superovulated by PMSG and hCG, inseminated and eventually slaughtered approximately 78 h after the expected time of ovulation. Genital tracts were flushed either immediately after slaughter (group A) or after 2 h storage at either 37 degrees C (group B) or 20 degrees C). Best results were achieved in group A, followed by group B and, by a wide margin, group C. Differences in viability of embryos became more evident with longer culture times.

Animals↗