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Biomedical subjects

R H Hunter

Publications and source records attributed to R H Hunter.

At least 73 records · Page 4Linked to original sources
PubMed1984

Sperm transport in the cow: peri-ovulatory redistribution of viable cells within the oviduct.

Using a surgical approach involving double ligatures and transection, together with subsequent recovery of the eggs, heifers mated at the onset of oestrus have been examined for progression of spermatozoa within the oviducts relative to the time of ovulation; the latter occurred 28-31 hours after the onset of oestrus. Evidence was obtained that spermatozoa competent to penetrate the egg(s) do not pass directly to the site of fertilisation at the isthmic-ampullary junction but instead are largely sequestered before ovulation in the caudal region of the isthmus, possibly for 18-20 hours or more. Thus, 3 of 14 eggs (21%) were fertilised when the oviduct was transected in pre-ovulatory animals 2.0 cm proximal to the utero-tubal junction 16 or more hours after mating compared with 7 of 8 eggs (88%) with a similar post-ovulatory transection 28-36 hours after mating (P less than 0.01). A redistribution of spermatozoa appears to be associated with imminent release of the egg. The distal portion of the oviduct is therefore seen as the functional sperm reservoir--that is the immediate source of viable spermatozoa at the time of ovulation. Parallels are drawn with storage of relatively quiescent sperm cells in the distal portion of the epididymal duct, and procedures of insemination are examined in the light of this storage rôle of the isthmus and the reported incidence of fertilisation in cattle.

Animals↗
PubMed1984

Pre-ovulatory arrest and peri-ovulatory redistribution of competent spermatozoa in the isthmus of the pig oviduct.

Using the surgical approach of post-coital ligation and transection of the distal oviduct at different times relative to ovulation, together with subsequent recovery of the eggs, gilts mated at the onset of oestrus were studied for progression of viable spermatozoa within the isthmus. Results are derived from 76 animals and examination of 1047 eggs. Transection of the isthmus 1.5-2.0 cm proximal to the utero-tubal junction at intervals from 3 to 36 h after mating prevented fertilization in 269 of 270 eggs, whereas 98% of 223 eggs were fertilized in the control oviducts. Transection at 38 h (pre-ovulatory), 40 h (peri-ovulatory) and 42-44 h (post-ovulatory) after mating yielded, respectively, 5%, 40% and 100% fertilization. The mean number of spermatozoa associated with the zona pellucida increased in a parallel manner. These results, and those obtained with ligatures placed closer to the site of fertilization just after ovulation, indicate a pre-ovulatory arrest of viable spermatozoa in the caudal region of the isthmus for 36 h or more followed by an active ad-ovarian redistribution.

Animals↗
PubMed1983

Transport of spermatozoa in the sheep oviduct: preovulatory sequestering of cells in the caudal isthmus.

Progression of ram spermatozoa within the sheep oviduct has been studied in relation to the time of ovulation. Ewes were mated at the onset of estrus and, at increasing intervals thereafter, the oviduct isthmus was transected 1.5-2.0 cm proximal to the utero-tubal junction. The incidence of fertilization and number of accessory spermatozoa were examined in eggs recovered 1 to 3 days after surgery. Ovulation occurred 24-26 hours after the onset of estrus. None of 52 eggs recovered from 48 oviducts transected up to 21 hours after mating was fertilized, nor were spermatozoa associated with the zona pellucida. Two of 33 eggs (6.1%) from 29 oviducts transected between 22 and 24 hours after mating were fertilized, while 3 of 14 eggs (21.4%) and 13 of 16 eggs (81.3%) were fertilized with transection at 25 and 26 hours, respectively. The mean numbers of accessory spermatozoa on eggs in the latter two groups were 0.7 (range 0-2) and 7.9 (range 0-26). Results from transection at 27-30 hours after mating indicated a progressive release and adovarian movement of spermatozoa. Viable spermatozoa are apparently sequestered in the caudal isthmus for as long as 17-18 hours, until shortly before ovulation, when a local transfer of ovarian follicular hormones is thought to facilitate their redistribution. The adrenergic stimulation of powerful adovarian waves of contraction in the isthmus at this time may also act to provoke the capacitation and hyperactivation of ram spermatozoa.

Animals↗
PubMed1983

Regulation of oviduct function in pigs by local transfer of ovarian steroids and prostaglandins: a mechanism to influence sperm transport.

Blood was collected from a prominent ear vein and from the arterioles supplying the caudal portion of each oviduct in 5 estrous animals. Sampling was arranged at 4 preovulatory intervals, and just after ovulation in the fifth animal. Steroid hormones and prostaglandins were determined by radioimmunoassay of plasma. Whereas the concentration of cortisol did not differ between peripheral and oviduct blood samples, the overall values for progesterone, androstenedione and estradiol were significantly higher in oviduct samples (P less than 0.001) - frequently by 5- to 10-fold or more. The concentration of these three hormones in oviduct blood corresponded, in most instances, with the number of preovulatory follicles or recent ovulations in the adjacent ovary but suitable statistical correlations could not be performed. Prostaglandin F2 alpha was also present in higher concentrations in oviduct compared with peripheral plasma (P less than 0.005), although pulmonary clearance of prostaglandins would have influenced the peripheral values. Differences in the concentration of prostaglandin E2 were not significant. A local transfer of follicular hormones from the ovarian vein to the ovarian and utero-tubal arteries is proposed as a means of regulating oviduct function. Elevated concentrations of steroids and prostaglandins transferred in this way would permit incisive changes in the patency and contractile activity of the isthmus, thereby facilitating the periovulatory phase of sperm transport from the caudal portion of the oviduct to the site of fertilization.

Animals↗
PubMed1982

Uterine secretion of prostaglandin F2 alpha in anaesthetized pigs during the oestrous cycle and early pregnancy.

Uterine blood was sampled by venepuncture or an indwelling catheter in a total of 33 cyclic gilts and 26 mated animals subsequently confirmed to contain embryos; jugular blood was obtained simultaneously from catheterised animals. Prostaglandin F2 alpha and progesterone were determined by radioimmunoassay of the plasma. The concentration of PGF2 alpha in uterine venous blood of cyclic animals remained below 1.0 ng/ml until the corpora lutea were 12 days old. Highest PGF2 alpha values were associated with 15-17 day corpora lutea, with a mean of 5.9 ng/ml for six samples on Day 17. Likewise, the PGF2 alpha concentration in the uterine blood of mated animals did not exceed 1.0 ng/ml until the corpora lutea were older than 12 days, and a mean value of 6.0 ng/ml was found by acute sampling with 15-day corpora lutea. The highest mean concentrations of PGF2 alpha in uterine blood from a series of 14 catheterised pregnant animals were 2.8 and 2.3 ng/ml, respectively, with 15- and 16-day corpora lutea. Values for PGF2 alpha on the 17th, 18th and 19th days of pregnancy showed a downward trend. There was considerable day to day variation in the mean uterine and peripheral concentrations of progesterone in mated animals, but there was no sustained depression in response to elevated PGF2 alpha concentrations. The results suggest that exocrine secretion of PGF2 alpha into the uterine lumen of pigs under the influence of trophoblastic oestrogens does not provide a sufficient explanation for the establishment of the corpora lutea of pregnancy. Further attention should be devoted to the luteotrophic--as distinct from anti-luteolytic--rôle of pig conceptuses at the time of maternal recognition of pregnancy. Circumstantial evidence for luteal sensitivity to chorionic gonadotrophins is included.

Animals↗
PubMed1982

Morphology, histology and steroid hormones of the gonads in intersex pigs.

Studies of 3 genetically female, intersex pigs revealed that only one showed oestrous cycles and lordosis, the other 2 exhibited various components of male sexual behaviour. Each uterus was a patent bicornuate structure, but 5 of the oviducts were incompletely formed. Two of the animals had bilateral ovotestes, whilst the third had a functional ovary on the right and an ovotestis on the left. The small ovarian portion of each ovotestis contained Graafian follicles which did not respond to a systemic injection of PMSG. The major portion of each ovotestis consisted of extensive interstitial tissue and seminiferous tubules devoid of germ cells. A structure closely resembling an epididymis adjoined the ovotestes. Concentrations of oestradiol and progesterone in plasma corresponded with those expected in the follicular phase of an oestrous cycle, but concentrations of testosterone represented approximately one-tenth of the values found in mature boars.

Animals↗
PubMed1982

Use of serum theophylline determinations during acute asthma therapy in children.

Analyses of 90 admissions to the Cincinnati Children's Hospital Center, Cincinnati, Ohio, were used to assess the effects of the routine availability of serum theophylline determinations (STD) in treating acute in-hospital asthma over three one-year review periods coinciding with the relative availability of STD. Significant differences were found between the first and third periods for the mean outpatient theophylline dose used on admission, the mean initial in-hospital intravenous dose, the mean initial oral dose during admission and the mean oral discharge dose. No statistical differences were noted in the length of hospital stay, duration of intravenous therapy or report of theophylline toxicity (despite the use of larger theophylline doses). Utilization of STD must be guided by cost-effective pharmacokinetic principles.

Acute Disease↗
PubMed1981

Distribution of spermatozoa in the utero-tubal junction and isthmus of pigs, and their relationship with the luminal epithelium after mating: a scanning electron microscope study.

The epithelial cell morphology and distribution in the utero-tubal junction and isthmus of pigs was documented by scanning electron microscopy around ovulation. In animals mated at different times before slaughter, our observations confirmed that the utero-tubal junction and posterior part of the isthmus regulate the transport of spermatozoa. The utero-tubal junction appears clearly as a form of mechanical valve strongly limiting the number of sperm cells penetrating the oviduct. The isthmus, and especially its posterior part poor in ciliated cells, is a storage place for spermatozoa which appear as though trapped in the epithelial folds. It remains to be demonstrated if they stay in such reservoirs due to the constriction of the lumen by the thick muscular wall of the duct, or to some chemotactic attraction by tubal secretions, or simply due to adhesion on the epithelium. Our study supports the hypothesis that transport of spermatozoa in the isthmus towards the site of fertilization depends in part on ciliary motion. The instant direction of propagation appears random for spermatozoa escaping from the reservoirs. Other factors such as tubal contractions probably ensure that the resultant movement is a progressive ascent.

Animals↗
PubMed1981

Sperm transport and reservoirs in the pig oviduct in relation to the time of ovulation.

The rate of establishment of a population of viable spermatozoa in the oviducts was studied using a technique of post-coital transection in conjunction with subsequent examination of the proportion of eggs fertilized. Gilts were mated early in oestrus (before ovulation) or on the 2nd day of oestrus (after ovulation), and 30, 45 or 60 min later the reproductive tract was sectioned just above or below the utero-tubal junction in a total of 48 animals; these were slaughtered 1 or 2 days after the operation. Some fertilized eggs were recovered from 40 animals, and 72.3% of the 679 eggs examined were fertilized. Mean percentage fertilization increased overall (a) with the time elapsing from mating to transection, (b) with transection below the utero-tubal junction compared with in the caudal isthmus, and (c) with a post-ovulatory versus pre-ovulatory mating. In a further 6 gilts, the results of transection in the lower third of the oviduct 3 h after mating at the onset of oestrus indicated that spermatozoa were initially sequestered in the caudal portion of the isthmus. It is concluded that a population of spermatozoa sufficient to give maximum fertilization is established in the oviducts within 1--2 h of mating, thereby affording protection from the uterine invasion of polymorphonuclear leucocytes.

Animals↗
PubMed1980

Transport of spermatozoa in the ewe: timing of the establishment of a functional population in the oviduct.

The technique of post-coital transection of the oviducts from the uterus at various intervals after mating has been used to establish how soon a population of spermatozoa competent to fertilize the egg(s) first appears in the oviduct of the ewe. Fertilised eggs were not found as a sequel to transection at 4 or 6 hrs after mating, whereas the incidence of fertilization in a small series of ewes was 30 p. 100 following transection at 8 hrs and 100 p. 100 at 10 hrs. The mean number of spermatozoa associated with the zona pellucida at these later times increased from 2 to 13.4. The results are interpreted as indicating only a gradual progression of viable spermatozoa from the cervix to the oviduct, although the possible contribution of a rapid phase of sperm transport to the events of fertilisation is discussed. Finally, the isthmus rather than the cervix is reasoned to act as the functional sperm reservoir at the time of ovulation, with some form of peri-ovulatory programming of sperm release from this region of the tract.

Animals↗
PubMed1979

Effect of obtrusive measures on antibiotic compliance.

The influence of compliance measurement activities on patient behavior was studied. The project measured the relationship among physical capsule counts, patient interviews, and the amounts of excreted ampicillin. The capsule counts and patient interviews were conducted in a manner that disguised their intent. Sixty college-age patients were assigned to one of three experimental groups: a telephone interview, a personal interview and capsule count, or a control group. Stimulation (interviews) occurred on the 2nd day of the prescribed regimen, and urine was collected on random days thereafter. Results indicated that both stimulation types were associated with more positive compliance rates. The influence diminished rapidly. The reactive influence of experimentor intervention associated with personal and phone communication was demonstrated.

Adult↗
PubMed1979

Comparison of five information services as sources for bioavailability data.

The usefulness of five drug information services in obtaining bioavailability data from journal literature is compared. The deHAEN Drugs in Use system, the Iowa Drug Information Service (IDIS), Index Medicus, MEDLINE and International Pharmaceutical Abstracts (IPA), each for a 10-year period, were searched for citations on bioavailability studies on the oral dosage forms of acetaminophen, lithium carbonate, phenytoin, nitrofurantoin and theophylline. Both quantity of references indexed and quality of data were considered. No significant difference was found in the mean value scores for the five services. Index Medicus provided 79 citations but required 7.7 hours of search time. MEDLINE yielded 62 citations but required only 1.1 hours to search. IPA, IDIS and deHaen had lower numbers of citations and intermediate search times. IPA, deHaen and Index Medicus all cited unique articles, with 11%, 7% and 3%, respectively. Index Medicus had the lowest percent of articles duplicated by two or more services (49%). The most comprehensive serch with the fewest duplicate citations would be obtained from searching deHaen's Drugs in Use, IPA and Index Medicus.

Biological Availability↗
PubMed1977

Steroid-binding proteins in follicular fluid and peripheral plasma from pigs, cows and sheep.

No unusual steroid-binding proteins that might react with the oocyte or its investments could be detected in follicular fluid. Corticosteroid-binding globulin occurred in follicular fluid from pigs, sheep and cows, and sex hormone-binding globulin occurred in follicular fluid from sheep and cows. The bulk of the steroid in follicular fluid is bound to albumin with low affinity, indicating that steroid molecules can readily be released, and oestrogen can react with the oocyte and granulosa cells in a manner analogous to that demonstrated for target cells bathed with interstitial fluid. Pigs lack a sex-hormone binding globulin in blood plasma and, hence, in follicular fluid. Because no proteins exist in follicular fluid that would compete with antibodies to bind steroids, direct radioimmunoassay of follicular steroids appears to be a valid technique.

Animals↗