Biomedical subjects

R Newcomb

Publications and source records attributed to R Newcomb.

53 records · Page 3Linked to original sources

PubMed1978

Non-surgical recovery of bovine embryos.

The non-surgical recovery of bovine embryos was examined using a three-lumen PVC catheter passed to the tip of each uterine horn. The recovery of eggs placed in Dulbecco's phosphate buffered saline, with protein was very efficient whether in boiling tubes or funnels. In the absence of protein egg recovery was considerably lower. In a group of 42 heifers, superovulated on two occasions, embryos were recovered non-surgically on day 7 after the first superovulation (Day 0 = oestrus) and surgically after the second. Laparotomy was performed on each occasion and the number of corpora lutea counted. Ovulation rate was lower at the second superovulation and a correspondingly greater recovery of embryos was obtained surgically (P less than 0.02). Non-surgical recovery rates from anaesthetised cows and heifers and from standing sedated heifers were found to be similar. The distance of the catheter tip from the utero-tubal junction (UTJ) significantly affected recovery rate (P less than 0.001). Best results were obtained when the catheter tip was within 5 cm of the UTJ. Most embryos were recovered in the first 100 ml of recovered medium. The method compares favourably with other reported methods.

Anesthesia↗

PubMed1978

Comparison of the fetal survival rate in heifers after the transfer of a embryo surgically to one uterine horn and non-surgically to the other.

When transfer of Day 7 embryos was surgically to the horn ipsilateral to the CL and non-surgically to the contralateral horn, fetal survival rate was 85 and 35% respectively. After non-surgical transfer to the ipsilateral and surgical transfer to the contralateral horn, fetal survival rate was 20 and 30% respectively.

Animals↗

PubMed1977

Physiological factors and the early embryo.

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Animals↗

PubMed1977

The effect of oxytocin treatment on the levels of prostaglandin F in the blood of heifers.

Six heifers with normal oestrous cycles were treated i.m. with 100 i.u. oxytocin on 3 consecutive days, commencing on Days 1-6 after oestrus, and the levels of prostaglandin (PG) F in posterior vena cava plasma were compared with pretreatment values. An increase of PGF in response to oxytocin was significantly influenced by day, with the greatest response occurring on Day 3 after oestrus. In an ovariectomized heifer the levels of PGF in posterior vena cava plasma increased 24 h after priming with oestradiol, but no further increase occurred after oxytocin injection. Peak levels of PGF were higher in the plasma of the posterior vena cava than in the jugular vein. Various storage conditions of the blood before centrifugation and freezing (--20 degrees C) produced significant differences in plasma levels of endogenous PGF, but storage experiments with added labelled PGF-2alpha indicated that the PG was stable in plasma and whole blood.

Animals↗

PubMed1976

Fundamental aspects of ovum transfer in cattle.

Although it may ultimately be possible to fertilise ovarian follicular oocytes in vitro, superovulation and insemination are currently the only practical method for obtaining a supply of fertilised ova. It is likely that this will remain true for sometime to come. Pregnant mares serum gonadotrophin (PMSG) is almost universally used for inducing superovulation, and response to it has recently been more reliably achieved by using, in addition, prostaglandin F2alpha to induce oestrus in superovulated donors. The recovery of fertilised ova from donors depends on the expected site of the ova within the genital tract, but both surgical and non-surgical methods involve suspending the ova in a stream of fluid which is collected into glass cups and examined microscopically. A variety of in vivo and in vitro environmental conditions affect the success of transfer of fertilised ova. These include the healthy state of the recovered ovum, the storage medium, the method and length of storage, the age of the ovum and the synchronisation of oestrus of donor and recipient.

Animals↗

PubMed1976

Paralysis of elevation of one eye a case report.

A vertical diplopia in a 53-year-old woman was diagnosed as euthyroid Grave's disease, which was arrested by systemic chemotherapy. Subsequent corrective surgery was effective.

Diplopia↗

PubMed1976

The storage of cow eggs at room temperature and at low temperatures.

The survival and development of cow eggs in the rabbit oviduct after storage at room temperature and after cooling and storage at 0-7-5 degrees C was examined. In PBS medium at room temperature 88% of Day-5 and 85% of Day-3 eggs showed normal development, but in TCM 199, 71% of Day-5 and only 49% of Day-3 eggs showed normal development. Duration of storage (1 1/2-2 hr or 6 1/2-7 1/2 hr) and cleavage stage before storage had no appreciable effect on development. Some retardation of development occurred in Day-3 eggs after 96 hr in the rabbit oviduct when compared to Day-5 eggs after 48 hr. Cooling of Day-5 and Day-6 eggs to 0-7-5 degrees C resulted in degeneration of a large proportion of eggs. Of the factors examined, storage medium (PBS or PBS+20%FCS), storage time (2 min, 24 hr) and storage temperature (0, 2, 5 or 7-5 degrees C) had little effect, but slower cooling rates tended to improve survival of eggs although the differences were not significant. More morulae (greater than 32 cells) than 8-to 24-celled eggs developed normally.

Animals↗

PubMed1975

Plasma oestrogen and progesterone in relation to superovulation and egg recovery in the cow.

Pregnant mares serum gonadotrophin (PMSG) was used in combination with prostaglandin F2alpha or its analogues to induce superovulation in 25 heifers. Total unconjugated oestrogen and progesterone were determined in peripheral plasma of these superovulated animals, and the levels compared with those found during the normal oestrous cycle. A very high level of oestrogen was found between day 3 and 6 after superovulation, and it seems likely that large unovulated follicles were responsible for the excess steroid. Similarly, progesterone levels were raised in the superovulated animal presumably due to production by the numerous corpora lutea. In two heifers, in which overstimulation of follicular development had occurred, there were no ovulations in one of the animals while in the other animal there were 16 ovulations but early regression of corpora lutea was indicated. It is concluded that the poor recovery of eggs on day 6 after superovulation could have been due to deleterious effects of high levels of oestrogen on either the motility of the genital tract causing the premature transport of eggs, or the properties of the zona pellucida.

Animals↗

PubMed1975