Biomedical subjects
Publications and source records attributed to R Newcomb.
This article provides results of a comparison between the Halstead-Reitan tapper and a 1988 computerized tapping program by Loong. Care should be taken in using the computerized tapper in diagnosis or assessment.
Multiple biologically active peptides arising from a common prohormone are sorted into distinct classes of dense core vesicles within the bag cell neurons of Aplysia californica. In this study, pulse-chase analysis, combined with subcellular fractionation on Percoll gradients, are used to define the location of the prohormone processing events within the secretory pathway. Initial cleavage of the prohormone occurs in a light cellular compartment associated with the Golgi apparatus. The amino-terminal processing intermediate then accumulates in a denser compartment containing small dense cores enclosed in membranous sacs, as well as larger immature vesicles. After 4 h, amino-terminal products are found primarily in a much denser compartment which consists of large and small dense core vesicles. These large and small vesicles can be separated from each other using Percoll gradient centrifugation and are found to be enriched in amino- and carboxy-terminal products, respectively. Lastly, membrane association experiments suggest differential binding to membranes, or integral membrane proteins, as a possible mechanism for sorting of amino- and carboxy-terminal products.
Methods of transferring one bovine embryo to the ipsilateral uterine horn have been compared. In heifers mid-ventral surgical laparotomy under general anaesthesia (n=22) was compared with flank surgery with paravertebral anaesthesia (n=21). Pregnancy rate was higher with a midventral approach (P less than 0.05) (77.3 per cent of 42.9 per cent respectively). In heifers mid-ventral surgery (n=36) was compared with two methods of non-surgical transfer either using the Cassou insemination gun (n=36) or a modification of it (n=39) with embryos collected on days 7, 8 or 10 after oestrus. There were no differences in pregnancy rate between methods or different ages of embryos (methods: 55.6, 55.6, 43.6 per cent respectively; Day: 48.8, 55.8, 48.1 per cent respectively) but the condition score of recipients affected success (P less than 0.05). Of 10 cows which each received an embryo using the modified Cassou gun eight became pregnant.
Fourteen heifers were superovulated five to 10 times using pregnant mare serum gonadotrophin (PMSG) and prostaglandin in a standardised regime which resulted in a mean interval of 42.1 days (SEM +/- 0.97) between treatments. There was a significant (P less than 0.02) fall in the mean ovulation rate at the second treatment when compared with the first but no significant difference between mean ovulation rate at the second and subsequent treatments. No significant difference between treatments in mean egg recovery rate or in the percentage of normal eggs recovered was demonstrated. Four heifers treated 10 times continued to respond with multiple ovulations on most occasions. At the end of the experiment 13 of the 14 heifers were inseminated and 12 conceived, requiring a mean of 1.67 services per pregnancy.
The effect of two dose levels (1000 and 2000 i.u.) of three different commercially available batches of PMSG on the ovarian response (ovulations and follicles greater than 10 mn) of 42 heifers was examined in a randomized incomplete block experiment. Each animal was subjected to two consecutive but different treatments. A significant effect of dose was observed and there were fewer ovulations, but no reduction in the number of follicles, after the second PMSG treatment. There was no evidence that the ovarian response was affected by the PMSG batch used.
Day 7 eggs (oestrus = Day 0) were surgically transferred singly to the uterine horn contralateral to the CL and heifers were either slaughtered on Day 24-26 (Group 1) or palpated per rectum on Day 42 (Group 2) to determine the presence of a developing conceptus and a maintained corpus luteum. There was a fall in pregnancy rate of the control heifers in Groups 1a (6/10) and 2a (2/10) (P = 0.085). Pregnancy rate was unaffected by progesterone treatments from Day 13 to the day before slaughter in Group 1b (8/10), or to Day 23 in Group 2b (2/10). Two of the conceptuses recovered in Group 1b were developing in the presence of regressed corpora lutea. There was, however, an increase in pregnancy rate in Group 2d (6/10) compared with Group 2a (2/10) when heifers were treated with hCG from Days 13 to 35 (P = 0.085). The results indicated that embryonic death is occurring after Day 24 and suggest that a change in the nature of the embryonic signal may be occurring at this time.
A surgical demonstration of the potential use of egg transfer for converting a herd of cattle from one breed to another (Jersey to Friesian) was undertaken on farm. Friesian donors were non-lactating but 50 per cent failed to respond adequately (greater than 3 ovulations) to treatment with PMSG (1500 to 3000 iu). Heifers yielded more ovulations and eggs than cows, but recovery rate was higher from cows (80 per cent cf 60 per cent). Fertilised eggs were recovered from old (13 years) cows, some of which had ceased to breed normally. Pregnancy rate after transfer of these eggs was normal. Purebred Friesian calves out of Jersey recipients were Friesian weight (male, 44.8 kg; female, 37.4 kg) and contrary to experience with crossbreds caused severe dystocia problems. Severity of dystocia was related to birth weight and sex of calf.
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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.
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.
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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.
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.
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.
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.
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.
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