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Biomedical subjects

D P Ryan

Publications and source records attributed to D P Ryan.

At least 55 records · Page 3Linked to original sources
PubMed1994

Ovarian follicular recruitment, granulosa cell steroidogenic potential and growth hormone/insulin-like growth factor-I relationships in suckled beef cows consuming high lipid diets: effects of graded differences in body condition maintained during the puerperium.

The effects of graded differences in body condition score (BCS) on ovarian follicular development, granulosa cell steroidogenic potential, and growth hormone (GH)-insulin-like growth factor-I (IGF-I) relationships were examined during the puerperium in beef cows fed high fat diets. Cows (n = 36) were allocated randomly about 90 d before expected calving to dietary treatments that resulted in BCS of 3 (very thin), 4 (thin), 6 (optimal) and 8 (obese) at parturition. Body weight and BCS were maintained after parturition by adjusting individual intakes of forage throughout the 17-d experiment, and all cows were fed a high lipid supplement (soybean oil; 0.44 kg/500 kg body weight) during this period. Follicular development in BCS 3 and 4 lagged behind that of BCS 6 and 8 throughout most of the study; however, cows in BCS 4 developed numbers of medium and large follicles by day 15 postpartum that were comparable to those of cows in greater BCS. Mean concentrations of total cholesterol (TCH) and total triglycerides (TG) in serum were greater (P < .05) for cows in BCS 8 vs. 3, 4 and 6 through days 12 (TCH) and 16 (TG) postcalving, respectively. High-density lipoprotein cholesterol (HDL-CH), progesterone and estradiol-17 beta concentrations in follicular fluid were not affected by BCS at ovariectomy (day 17 postpartum). Addition of insulin and low-density lipoprotein (LDL) to culture media maximized (P < .05) production of progesterone by granulosa cells, but in vivo BCS treatments had no effect. Serum GH concentrations were elevated (P < .05) in cows in BCS 3 and 4 compared to those in BCS 6 and 8 throughout the puerperium. Serum IGF-I tended (P < .10) to increase during the first few days after parturition, and both serum and follicular fluid IGF-I increased (P < .02 and P < .001, respectively) with increasing BCS. Data indicate that cows calving in BCS < 4, and fed such that weight and BCS do not increase, are unlikely to respond to short-term dietary fat supplementation.

Animals↗
PubMed1993

Biochemical immaturity of lungs in congenital diaphragmatic hernia.

Neonates with congenital diaphragmatic hernia (CDH) continue to have unacceptably high mortality rates. To better understand the associated pulmonary pathology we measured biochemical parameters of lung maturity in neonatal rats with or without congenital diaphragmatic hernia created by maternal feeding of a single dose of nitrofen on day 9.5 or day 11.5 of gestation. Lungs from neonatal rats with large CDH (n = 9, 5 right-sided, 4 left-sided) had a significantly lower lung weight (P = .0001), lung weight/body weight ratio (P = .0001), disaturated phosphatidylcholine (DSPC) per microgram DNA (P < .005), total DSPC (P = .0001), total DNA (P < .05), protein per microgram DNA (P < .05), and total protein content (P < .005) when compared with lungs from the litter mates without congenital diaphragmatic hernia (n = 10). The lungs of rats with hernia also had significantly higher DNA concentrations (P < .05) and glycogen concentrations (P < .05). These data demonstrate that lungs in neonatal rats with large CDH are biochemically immature. Treatment directed toward correcting the pulmonary biochemical immaturity of affected fetuses before birth may improve the prognosis for these babies.

Animals↗
PubMed1993

Comparing early embryo mortality in dairy cows during hot and cool seasons of the year.

The objectives of this study were to identify the level and stage of embryonic mortality that occur in dairy cows during hot and cool seasons of the year. Experimental dairy cows, of varying ages, were artificially inseminated with frozen-thawed semen from proven Holstein sires. Females on each dairy unit were then randomly allocated to one of three experimental groups after partitioning by day of artificial insemination, days post partum, parity, and current milk production level. In Group I and Group II, nonsurgical embryo collection was performed on each cow using Dulbecco's phosphate-buffered saline as the flushing medium. Embryos from cows in Group I were collected on Days 6 or 7 post insemination during the hot (n=93) and cool (n=64) seasons. Embryos from cows in Group II were collected on Days 13 or 14 post insemination during the hot (n=97) and cool (n=63) seasons. In Group III, contemporary control cows were also inseminated during the hot (n=106) and cool (n=106) seasons, and fetal heart beat was evaluated via ultrasound between Days 25 and 35 following insemination. Embryo viability decreased (P<0.05) from 59% at Day 7 to 27% at Day 14 in the hot season, but was not decreased during the cool season (52 vs. 60%). Pregnancy rate at Days 25 to 35 was 21% in the hot season, which was less (P<0.05) than the 36% in the cool season. The percentage of unfertilized ova collected in both the hot and cool seasons suggests that fertilization failure was not affected by season of breeding. In summary, embryonic loss after Day 7 of pregnancy appears to be a problem in this hot, dry climate.

Journal Article↗
PubMed1993

Using hormone-treated pregnant cows as a potential source of oocytes for in vitro fertilization.

In vivo collection of oocytes during pregnancy may be alternative method of obtaining gametes for in vitro fertilization (IVF) from genetically superior gestating cattle. The objectives of this experiment were to induce follicular growth in mature beef cows during each trimester of pregnancy, and then to collect oocytes and verify oocyte competency by IVF and subsequent embryo culture in vitro. Cyclic beef cows in Treatment A and pregnant cows in Treatment B were administered a total dose of 40 mg of FSH in descending dose levels (6, 5, 4, 3 and 2 mg) twice daily for 5 consecutive days. Cows in Treatment A were administered 25 mg of PGF(2)alpha and in Treatment B an equal volume of 0.9% saline at the seventh FSH injection. Pregnant cows in Treatment C were administered neither FSH nor PGF(2)alpha and served as a control group. Following a gonadotropin treatment, the ovaries of each female were evaluated for follicular development by ultrasonography. Oocytes were collected by follicle aspiration from cows in the first trimester. Following IVF procedures, the embryos were co-cultured on caprine oviductal cells, or in the chicken embryo co-culture system, or were placed in goat oviducts in vivo. The mean number of follicles per ovary 12 hours after FSH treatment was not different for cows in Treatments A and B, (8.1 vs 7.7) and both numbers were greater (P<0.05) than the 1.1 follicles per ovary for the control cows in Treatment C. Oocytes collected in vivo and exposed to IVF, resulted in 20% cleaving, and of these embryos 50% developed to the morula stage in culture. In summary, stimulating supplemental follicular development with FSH treatment during pregnancy and collecting the oocytes for IVF may be an alternative method for obtaining supplemental gametes from valuable donor cattle.

Journal Article↗
PubMed1993

Mortality and respiratory failure in a pediatric burn population.

A 9-year retrospective review of 1,242 admissions to a tertiary burn center identified 137 patients who were intubated and ventilated for a critical airway or pulmonary problem. These patients varied in age from 2 months to 18 years with an average total body surface area (TBSA) burn of 55%. We evaluated this group for evidence of respiratory failure (ARF) as defined by the respiratory failure index (RFI) (PaO2/FIO2 < or = 300). While only 23% of admissions to the burn center were related to flame burns, these injuries accounted for 82% of children who had ARF. Forty-two percent of these intubated children had abnormalities on their admission chest x-ray and 61% of this cohort developed evidence of ARF as defined by the RFI. The development of sepsis along with ARF regardless of TBSA involvement doubles the mortality of ARF alone. Early burn wound excision and grafting is critically important to prevent the late complication of sepsis. We carefully monitor ventilator settings to insure low peak inspiratory pressures, allowing relative hypercapnia and avoiding hyperoxia. Despite an increased number of admissions and critically injured children, we have not seen an increase in morbidity and have had a 53% reduction in mortality in the last 2 years with these techniques. We believe this management offers the best outcome for the pediatric burn victim and would recommend this strategy to other centers dealing with these severely injured children.

Adolescent↗
PubMed1993

Effect of caprine arthritis-encephalitis virus infection on milk cell count and N-acetyl-beta-glucosaminidase activity in dairy goats.

Bacteriology, somatic cell counts (SCC) and N-acetyl-beta-glucosaminidase (NAGase) activity determinations were conducted on milk samples collected from does in three dairy herds with caprine arthritis-encephalitis virus (CAEV) infection. In two herds, CAEV-infected does were more likely to have a subclinical bacterial infection of the udder than CAEV-free does (P < 0.05). Does with CAEV but no bacterial udder infection had significantly greater mean SCC and NAGase activity than CAEV-free does without udder infection (P < 0.01). In two herds, changes in milk SCC and NAGase associated with CAEV infection were similar to those produced by coagulase-negative staphylococcal infections. The findings confirm that indirect indicators of bacterial mastitis infection may have reduced specificity in dairy goat herds with CAEV.

Acetylglucosaminidase↗
PubMed1993

Evidence for maternal behavior as a requisite link in suckling-mediated anovulation in cows.

Some component of the suckling process inhibits LH secretion and delays postpartum ovulation in beef cows. To investigate a possible role for maternal behavior in suckling-mediated anovulation, 27 crossbred beef cows were randomly allotted to 1 of 3 groups: 1) alien (dam suckled by alien calf; n = 11); 2) own (dam suckled by own calf; n = 8); and 3) weaned (calf removed for 6 days; n = 8). Beginning 14-17 days after parturition (experimental Day 0), cows were control suckled (10 min every 6 h) in stanchions for 6 days by either their own calf or by an alien calf or were weaned. Mean LH pulse frequencies in the alien and weaned groups were similar but were elevated (p < 0.02) on experimental Days 2 and 4 compared to those in the own group. The incidence of luteal activity by experimental Day 10 was greater (p < 0.01) for the alien (72.2%) and weaned groups (75.0%) than for the own group (12.5%). Frequency of oxytocin release following suckling was greater (p < 0.01) in the own group than in the alien group (Day 2: 100% vs. 36.4%; Day 4: 100% vs. 54.6%), whereas suckling-induced release of prolactin was similar for both groups. Data provide evidence that the mother-offspring bond is an important link in suckling-mediated inhibition of LH secretion and ovulation.

Aggression↗
PubMed1992

Treatment of acute pulmonary failure with extracorporeal support: 100% survival in a pediatric population.

Since February 1990, five children, aged 10 days to 6.5 years, were treated with extracorporeal lung support at our hospital for acute, unrelenting pulmonary failure. Two had viral pneumonia: one with respiratory syncytial virus (RSV) bronchiolitis, and one with herpes simplex virus pneumonia, encephalitis, and disseminated intravascular coagulation. One presented with a febrile illness followed by a pulmonary hemorrhage. Two patients had adult respiratory distress syndrome (ARDS) complicating severe systemic illnesses, toxic epidermal necrolysis in one and cat scratch disease with encephalitis in the other. All children had diffuse parenchymal lung disease by chest x-ray. On maximum medical management all patients were developing carbon dioxide retention and progressive hypoxemia, exceeding previously established NIH study criteria for extracorporeal treatment. Three children (10 days, 2 months, 13 months) were placed on venoarterial support and two children (20 months and 6.5 years) were placed on venovenous extracorporeal support (ECCO2R). Three of the five had open lung biopsies performed, which showed findings consistent with a moderate to severe cellular phase of ARDS. No viral inclusions were found in the patient with RSV infection. One hundred percent immediate survival was achieved in this patient population. Average duration of support was 330 hours (range, 89 to 840). Following completion of extracorporeal support, all children were successfully weaned from the ventilator with an average time to extubation of 23.2 days (range, 2 to 58 days). One child died of congestive heart failure following palliative surgery for a complex noncyanotic congenital cardiac lesion 35 days after successfully weaning from extracorporeal support for an acute febrile illness and pulmonary hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Ectopic class II major histocompatibility antigens in Hirschsprung's disease and neuronal intestinal dysplasia.

Although the etiology of Hirschsprung's disease and neuronal intestinal dysplasia remains obscure, both have histological abnormalities involving ganglion cells and neuronal elements. Searching for a common pathway that may inhibit normal maturation of neurogenic precursors, we examined the possible role of an immune mechanism in the maldevelopment of the enteric neural network. Six patients with Hirschsprung's disease were studied by comparing biopsy specimens from diseased colon with ones taken from proximal ganglionic colon in the same patients. These were similarly compared with colonic biopsy specimens from patients studied with chronic constipation or bowel removed at the time of operation for other disorders. Biopsies were taken from four other patients with neuronal intestinal dysplasia. Each was examined by hematoxylin & eosin staining, acetylcholinesterase histochemistry, and immunohistochemistry of major histocompatibility complex (MHC) class I and class II antigens. All rectal samples from Hirschsprung's disease patients exhibited elevated acetylcholinesterase histochemistry and absent ganglia to confirm the diagnosis. These findings were correlated with marked elevation of class II MHC in the aganglionic area, whereas the proximal normal ganglionic segments showed no elevation. Rectal biopsy specimens from patients with chronic constipation exhibited no such elevation. A similar elevation of class II MHC was detected in the mucosa and submucosa of all four patients with the rare neuronal intestinal dysplasia disorder whose diagnosis was confirmed by giant ganglia in Auerbach's plexuses, aberrant Meissner's ganglia in the lamina propria mucosa, and giant neurofibrils in the mucosa and submucosa. The correlation of elevated class II MHC in these two neuronal dysfunction disorders may indicate an underlying autoimmune mechanism as is seen in thyroiditis and insulin dependent diabetes mellitus.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1992

Effect of heat-stress on bovine embryo development in vitro.

Chronic elevation of uterine temperature has long been known to increase embryo mortality in dairy cattle. Short-term elevation in temperature of mouse embryos to 43 degrees C (acute) has been shown to induce intracellular production of heat-shock proteins. In this study, in vitro development of bovine embryos was assessed during short-term (60 h) coculture with oviduct epithelial cells at 38.6 degrees C (T1), 40 degrees C (T2), 38.6 degrees C after a prior pulse treatment (20 min) at 43 degrees C with 5% CO2 (T3), or 38.6 degrees C after a prior pulse treatment (20 min) at 43 degrees C with 100% CO2 (T4). During incubation, embryos cocultured at 40 degrees C had a greater (P < .05) mean embryo development score at 36 h than embryos cocultured at 38.6 degrees C. At 60 h of incubation, embryo development scores were greater (P < .05) for embryos cultured at 38.6 degrees C than for those cocultured at 40 degrees C. The number of embryos hatched at 60 h was similar after coculture at 38.6 degrees C (T1) or a prior pulse treatment with 5% CO2 and 43 degrees C (T3), but the embryo development score at 60 h was greater (P < .05) for the pulse-treated embryos. Embryos in T4 had greater (P < .05) embryo development scores than did T1 embryos from 36 through 60 h. Pulse treatment (T4) resulted in a greater (P < .05) number of hatched embryos at 60 h than T1, T2, and T3. These results indicate a detrimental effect of a chronic elevation in temperature that was evident shortly after embryo hatching.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Ovarian follicular characteristics, embryo recovery, and embryo viability in heifers fed high-fat diets and treated with follicle-stimulating hormone.

Postpubertal beef heifers (n = 55) were used to examine the effects of high-fat diets, independently of energy intake, on nonesterified fatty acid and lipoprotein metabolic patterns, ovarian follicular dynamics, and embryo recovery/viability after FSH superstimulation. High-lipid (HL) diets (5.4% added fat) increased (P < .01) serum concentrations of cholesterol, but not of nonesterified fatty acids, during the 35-d period before FSH treatment. Development of medium-sized (5 to 9.9 mm) follicles was enhanced (P < .05) during this period in heifers fed the HL diet. The HL diet increased total cholesterol (P < .05) and progesterone (P = .14) concentrations in follicular fluid obtained at ovariectomy (n = 10) 60 h after the onset of FSH treatment, but neither estradiol-17 beta nor androstenedione was affected. Granulosa cells recovered from FSH-induced, estrogen-active follicles in heifers fed the HL diet produced greater quantities of progesterone (P = .06) and less estradiol-17 beta (P < .05) in vitro than did granulosa cells from heifers fed the normal lipid diet. Dietary treatment did not influence FSH-stimulated recruitment of medium and large follicles, number of ovulations, embryo recovery, or embryo viability. Data suggest that increments in dietary fat intake can alter specific aspects of ovarian steroidogenic potential and can increase the population of medium-sized follicles theoretically available for maturation and harvest during the estrous cycle. However, conditions that limited the latter process in the current experiment are not understood and require further investigation.

Animals↗
PubMed1992

Luteal maintenance in cattle after conceptus death during the first trimester of gestation.

The objectives of this experiment were to evaluate effect of age of the conceptus at death on subsequent interval to estrus and to determine whether prostaglandin F2 alpha (PGF) treatment after induced conceptus death would reduce interval to estrus. Sixty-four beef cows were diagnosed pregnant by ultrasonography between 24 and 50 d of gestation. Nine pregnancy groups were identified; each encompassed a 3-d interval from d 24 through 50 of gestation. Cows were allocated at random within pregnancy group to be treated with colchicine to induce conceptus death. Forty-eight hours after colchicine treatment, conceptus death was verified by ultrasonography and each animal received either saline or PGF. There was no evidence of an effect of age of conceptus at death on the subsequent interval to estrus after either saline or PGF. Interval to estrus after saline was 13.5 +/- .8 d, which was greater (P less than .01) than the 6.2 +/- .8 d after PGF. After saline, the estimate for the linear effect of time on serum progesterone (P4) was -1.32 +/- .36 ng/d and was less (P less than .05) than -2.83 +/- .36 ng/d for cows given PGF. Cows were exposed to fertile bulls at the first postabortion estrus. Pregnancy rates were 37.5% for cows given saline vs 31.3% for those given PGF. These results indicate that interval to estrus after conceptus death between 24 and 50 d of gestation is not affected by the age of the conceptus and can be reduced by PGF treatment.

Animals↗
PubMed1992

Evaluating two different evaporative cooling management systems for dairy cows in a hot, dry climate.

Milk production, rectal temperature, live weight gain, reproductive performance, and weather data were obtained on 150 Holstein cows managed under two cooling systems on a large dairy farm in Saudi Arabia during the summer months. Cows were paired at the onset of the trial according to days postpartum, lactation number, and current milk production. Females were then allocated either to a system that forced air, precooled by evaporative cooling, over the cows or to a system that alternately showered a fine mist onto the surface of the cows and then forced air at ambient temperature over them. The cows receiving evaporative cooling and those with spray and fan cooling were on sand and on slatted concrete floor, respectively, during the periods of cooling. The onset of estrus was observed during the night when the cows preferred the unshaded corral. For the 120-d trial period, 84% (62 of 75) of the cows receiving evaporative cooling and 60% (44 of 75) of the cows receiving spray and fan cooling became pregnant. In the evaporative cooling system, the pregnancy rate per insemination was 35.2% (179 inseminations) versus 23.2% (194 inseminations) for spray and fan cooling. The mean postpartum interval to pregnancy was 117.6 d for the evaporative cooling cows and 146.7 d for spray and fan cooling cows. The evaporative cooling system, with its open shades and sand bedding, enhanced reproductive performance and milk production compared with that of cows cooled with a spray and fan system with slatted flooring in this hot climate.

Air Conditioning↗
PubMed1991

Laryngotracheoesophageal cleft (type IV): management and repair of lesions beyond the carina.

Since the first successful repair of a complete laryngotracheoesophageal cleft (LTEC) to the carina in 1982, three newborn infants were observed with a particularly difficult variant in which the cleft extends beyond the carina into the mainstem bronchi. This type IV LTEC creates a long common tracheoesophagus, whose successful separation requires meticulous preoperative, operative, and postsurgical care. Three infants had complete surgical repair at our institution at 29, 49, and 225 days old and survived a minimum of 8 months. Recurrent tracheoesophageal fistulae at the thoracic inlet occurred in two infants, but was not observed in one patient when sternocleidomastoid muscle was interposed between the trachea and esophagus in the neck. Microgastria is an associated finding in each infant with the tracheoesophageal cleft extending beyond the carina. The small stomach is problematic as it is anatomically inadequate for any antireflux procedure and has not grown well, even with prolonged feeding. Early cleft repair is essential to prevent the development of chronic lung disease secondary to recurrent aspiration. The techniques to make the diagnosis, the preferred treatment to initially protect the airway, a single-stage operation performed simultaneously through the chest and neck to definitively repair the cleft, and finally the intraoperative and postoperative management critical for an optimal outcome are described.

Abnormalities, Multiple↗
PubMed1991

Frequency of twin births among Holstein-Friesian cows in a warm dry climate.

The objectives of this study were to examine 1) the effect of parity of dam and season of birth on the incidence of twins in Holstein-Friesian cattle in a warm, dry climate and 2) the sex ratio, gestation period and birth weight of calves born. Natural calvings (n=24,843) from nine dairy farms in Saudi Arabia were evaluated over an 8-year period. The calendar year was divided into six bimonthly intervals to identify a possible seasonal effect on the number of natural twins born (twinning rate). The twinning rate increased (P<0.05) from 1.0% (103/10,094) at first calving to 8.0% (1,178/14,749) for all the subsequent calvings. The twinning rate was similar with the second calving (P2) at 7.0% (417/5,929), the third calving (P3) at 7.5% (218/2,896), and the fourth calving (P4) at 7.8% (147/1,864). Correspondingly, cows having >or=five calves had a higher (P<0.01) twinning rate at 9.0% (164/1,805) than cows with too, three or four calvings collectively at 7.3% (782/10,689). The seasonal effect on twinning rate was significant within all parity calvings except in primiparous females. The peak twinning rate occurred in the third season interval (May/June) at 9.3% (66/708) with P2, at 13.0% (34/262) with P3, at 13.8% (27/196) with P4, and at 12.5% (23/184) with P5 females. The male to female ratio was different (P<0.01) for multiparous females (55:46; n=12,305). The ratio of males to females (55:45) was also different (P<0.01) for all twin pairs (n=1,151), evaluated in the study. The gestation period for cows with single calves was 8.5 days longer (P<0.05) than that of cows carrying twin calves. The birth weight of single calves was 13.1 kg greater (P<0.05) than that of twin calves. The reason for the marked increase in the twinning rate during the warmest months may be explained by greater embryo mortality in the hot vs cool months.

Journal Article↗
PubMed1991

Pregnancy rates in dairy cows following the administration of a GnRH analogue at the time of artificial insemination or at mid-cycle post insemination.

Lactating Holstein dairy cows (n=1,533) were allocated to one of three treatment groups, with Group I (n=514) receiving 10 microg of a GnRH analogue (buserelin) at artificial insemination (AI) and Group II (n=503) receiving 10 microg of the same analogue at both the time of AI and at 12 days post AI. Herdmates in Group III (n=516) were inseminated on the same day and served as contemporary AI controls. The trial was conducted on five large dairy farms during the spring and summer months in Saudi Arabia. Pregnancy rates were determined by palpation per rectum between 33 and 50 days following AI. The first service pregnancy rate for the control cows (42.4%) was lower (P<0.05) than that for cows treated with the GnRH analogue at AI (48.8%) or for the combined treatment at AI and at Day 12 post AI (51.5%). No additive effect on the pregnancy rate was noted from the combined analog treatment. The overall increase in pregnancy rate from the analogue treatment at AI resulted from an 11% increase in pregnancy rate in first parity cows over that of contemporary controls (P<0.05) and a 14.7% increase in pregnancy for cows mated at 40 to 59 days post partum and treated with the analogue at AI over that of the corresponding controls (P<0.05). The pregnancy rates from repeat AI (interval<or=30 days) were similar across treatments (45.7% for Group I, 42.9% for Group II and 47.8% for Group III). In this study, the GnRH analogue may have enhanced the ovulation rate and possibly luteal function in cows with reduced hypothalamic GnRH release under environmental stress.

Journal Article↗