Effect of music-movement synchrony on exercise oxygen consumption.

AIM: Past research indicates that endurance is improved when exercise movements are synchronised with a musical beat, however it is unclear whether such benefits are associated with reduced metabolic cost. We compared oxygen consumption (.VO2) and related physiological effects of exercise conducted synchronously and asynchronously with music. METHODS: Three music tracks, each recorded at three different tempi (123, 130, and 137 beats.min-1), accompanied cycle ergometry at 65 pedal revolutions.min-1. Thus three randomly-assigned experimental conditions were administered: slow tempo asynchronous, synchronous, and fast tempo asynchronous. Exercise response of .VO2, HR, and ratings of perceived exertion (RPE), to each condition was monitored in 10 untrained male participants aged 21.7±0.8 years (mean±SD) who cycled for 12 min at 70% maximal heart rate (HR). RESULTS: Mean .VO2 differed among conditions (P=0.008), being lower in the synchronous (1.80±0.22 L.min-1) compared to the slow tempo asynchronous condition (1.94±0.21 L.min-1; P<0.05). There was no difference in HR or RPE among conditions, although HR showed a similar trend to .VO2. CONCLUSION: The present results indicate that exercise is more efficient when performed synchronously with music than when musical tempo is slightly slower than the rate of cyclical movement.

Ipratropium bromide plus nebulized albuterol for the treatment of hospitalized children with acute asthma.

OBJECTIVE: To determine whether the addition of repeated doses of nebulized ipratropium bromide (IB) to a standardized inpatient asthma care algorithm (ACA) for children with status asthmaticus improves clinical outcome. STUDY DESIGN: Children with acute asthma (N = 210) age 1 to 18 years admitted to the ACA were assigned to the intervention or placebo group in randomized double-blind fashion. Both groups received nebulized albuterol, systemic corticosteroids, and oxygen according to the ACA. The intervention group received 250 microg IB combined with 2.5 mg albuterol by jet nebulization in a dosing schedule determined by the ACA phase. The placebo group received isotonic saline solution substituted for IB. Progression through each ACA phase occurred based on assessments of oxygenation, air exchange, wheezing, accessory muscle use, and respiratory rate performed at prescribed intervals. RESULTS: No significant differences were observed between treatment groups in hospital length of stay (P =.46), asthma carepath progression (P =.37), requirement for additional therapy, or adverse effects. Children >6 years (N = 70) treated with IB had shorter mean hospital length of stay (P =.03) and more rapid mean asthma carepath progression (P =.02) than children in the placebo group. However, after adjustment was done for baseline group differences, the observed benefit of IB therapy in older children no longer reached statistical significance. CONCLUSION: The routine addition of repeated doses of nebulized IB to a standardized regimen of systemic corticosteroids and frequently administered beta-2 agonists confers no significant enhancement of clinical outcome for the treatment of hospitalized children with status asthmaticus.

Pediatric asthma epidemiology: incidence, morbidity, and mortality.

Despite significant advances in understanding the pathophysiology of asthma and the development of pharmacologic agents for treatment, asthma prevalence, morbidity, and mortality continue to increase in most countries. This Article focuses on the epidemiology of asthma, specifically on the prevalence, incidence, morbidity, and mortality associated with pediatric asthma.

Pediatric asthma disease management.

The prevalence of asthma in children in the United States is estimated at more than 5% of the population, and it has risen more than 40% in the previous decade. Several guidelines for the management of acute and chronic asthma exist, and they all emphasize several basic components including state-of-the-art pharmacologic treatment, trigger avoidance, and patient self-management skills. This Article highlights the necessary components for pediatric asthma disease management to insure a smooth continuum of care across all disciplines and settings.

Regulation of proopiomelanocortin messenger ribonucleic acid levels in the ovine fetal anterior pituitary in vitro.

Parturition in sheep is dependent upon maturation of the fetal hypothalamo-pituitary-adrenocortical (HPA) axis. Anterior pituitary expression of the ACTH precursor, proopiomelanocortin (POMC), increases during the final days of gestation in spite of exponentially increasing fetal plasma cortisol levels. Lesion of the hypothalamic paraventricular nucleus prevents the late gestation increase in POMC mRNA. The purpose of this study was to examine glucocorticoid, corticotropin releasing factor (CRF) and arginine vasopressin (AVP) regulation of POMC mRNA levels in fetal anterior pituitary corticotropes in vitro and to address potential interactions between glucocorticoids and neuropeptides in regulating POMC. Anterior pituitaries from fetal sheep at two gestational ages (dGA; 118-125 dGA, n=9; 140-144 dGA, n=7) were enzymatically dispersed. POMC mRNA levels were determined at 24, 48 and 72 h post-dispersion. CRF, AVP and dexamethasone (DEX) regulation of POMC mRNA were determined at 24 and 72 h post-dispersion. The capacity of CRF and AVP to modulate DEX suppression of POMC mRNA levels was also examined. POMC mRNA was elevated at 24 h (P<0.01) and 48 h (P<0.05) post-dispersion compared to 0 h (immediately post-dispersion) in 140-144 dGA but not 118-125 dGA corticotropes. DEX suppressed POMC mRNA in a dose-dependent manner (when administered at 24 h post-dispersion) in the 140-144 dGA anterior pituitary cells but not 118-125 dGA anterior pituitary cells. Administration of DEX (10 nM) at 0 h prevented the increase in POMC mRNA levels observed at 24 h post dispersion in the 140-144 dGA group. Neither CRF nor AVP (administered at either 24 or 72 h post-dispersion) altered POMC mRNA levels in either 118-125 or 140-144 dGA anterior pituitary cells. Continuous exposure of anterior pituitary cells with either CRF or AVP (50 pM) through 96 h increased (P<0.05) POMC mRNA. No synergistic or additive effects were observed with CRF and AVP. Four hour pretreatment with CRF but not AVP (100 nM at 24 h post-dispersion) attenuated (P<0.05) DEX suppression of POMC mRNA levels in 140-144 dGA corticotropes. In conclusion, our results indicate that direct glucocorticoid suppression of POMC expression in fetal sheep initiates between approximately 120 and approximately 140 dGA, coincident with the period of gestation when fetal plasma cortisol is exponentially rising. Further, while short duration exposure of fetal corticotropes to either CRF or AVP had no effect on POMC mRNA, CRF appears capable of interfering with glucocorticoid suppression of POMC mRNA. The latter observation provides a potential mechanism via which the fetal PVN may counter rising fetal plasma cortisol concentrations resulting in the previously observed late gestation increase in anterior pituitary POMC mRNA.

Corticotropin-releasing factor receptor expression in the pituitary of fetal sheep after lesion of the hypothalamic paraventricular nucleus.

Both the capacity of CRF to release ACTH and the number of binding sites for CRF in the anterior pituitary decline during the final weeks of gestation in fetal sheep. The present study examined regulation of pituitary CRF receptor expression by the hypothalamic paraventricular nucleus (PVN) during late gestation in fetal sheep. Bilateral radiofrequency lesions of the PVN (PVN-Lx; n = 4) or sham lesions (SHAM; n = 5) were performed in fetal sheep at 118-122 days of gestational age (dGA). Pituitary glands from PVN-Lx and SHAM fetuses were collected at 139-142 dGA (term, approximately 148 dGA). Dual-label in situ hybridization was performed using a digoxigenin-labeled ovine POMC complementary RNA, together with a 35S-labeled ovine CRF type I (CRF1) receptor complementary RNA, to localize and quantify CRF1 receptor mRNA in POMC-hybridizing cells. Binding of [125I]-ovine CRF was also examined in the fetal pituitary of both PVN-Lx and SHAM fetuses using in situ autoradiography. The hybridization signal for the CRF1 receptor mRNA was primarily restricted to POMC-expressing cells in the anterior pituitary of both PVN-Lx and SHAM fetuses; no hybridization signal for the CRF1 receptor was observed in the neurointermediate lobe (NIL) in either group. The hybridization signal for CRF1 receptor mRNA in anterior pituitary corticotropes of PVN-Lx fetuses was significantly lower in both the inferior and superior regions of the anterior pituitary, compared with SHAM fetuses (P < 0.05). In the inferior region of the anterior pituitary, the percentage of POMC-hybridizing cells containing CRF1 receptor hybridization signal was significantly greater in PVN-Lx (90+/-7%; mean +/- SEM), compared with SHAM (67+/-6%; P < 0.05) fetuses. No differences in the percentage of POMC cells containing CRF1 receptor hybridization signal were observed in the superior region of the anterior pituitary between PVN-Lx (89+/-8%) and SHAM (87+/-9%). Binding of [125I]-ovine CRF (oCRF) was significantly greater in anterior pituitaries of PVN-Lx (140+/-19 mean arbitrary densitometry U +/- SEM), compared with SHAM (73+/-23; P < 0.05) fetuses. For both PVN-Lx and SHAM fetuses, there were no differences within group in [125I]-oCRF binding between the inferior and superior regions of the anterior pituitary. A weak, but significant (P < 0.05), autoradiographic signal for [125I]-oCRF binding was observed in the NIL of both SHAM and PVN-Lx fetal sheep. The level of [125I]-oCRF binding was significantly lower in the NIL, compared with anterior pituitary, for both SHAM (P < 0.01) and PVN-Lx fetuses. There were no differences in [125I]-oCRF binding in the NIL between SHAM and PVN-Lx fetal sheep. Our findings support a role for the PVN in regulating anterior pituitary CRF1 receptor expression in the late-gestation sheep fetus.

Expression of proopiomelanocortin and prohormone convertase-1 and -2 in the late gestation fetal sheep pituitary.

The biological activity of fetal plasma immunoreactive ACTH has been reported to increase during the final weeks of gestation in fetal sheep, indicative of enhanced processing of POMC to ACTH. The present study was aimed at examining the expression and localization of the prohormone convertases, PC1 and PC2, in the pituitary of fetal sheep during the final weeks of gestation. Pituitaries were obtained from fetal sheep during the final 50 days gestation (dGA) at 100-107 dGA (n = 6), 117-121 dGA (n = 6), 126-130 dGA (n = 7), and 144-147 dGA (n = 8; term = approximately 148 dGA). Pituitaries were cryosectioned and subjected to dual labeling in situ hybridization using 35S-labeled PC1 and/or PC2 complementary RNA probes with a digoxigenin-labeled POMC complementary RNA to localize and quantify PC1 and PC2 messenger RNA (mRNA) in POMC-hybridizing cells. Immunocytochemistry was also performed to assess coexpression of PC1 and PC2 with ACTH in the fetal pituitary. PC1 mRNA was heterogeneously distributed in the anterior pituitary (AP) at all gestational ages examined, with hybridization signals observed over POMC-expressing cells (corticotropes) as well as over noncorticotrope phenotypes. The inferior region of the AP contained an approximately 3-fold greater (P < 0.01) percentage of POMC cells containing PC1 transcripts compared with the superior region of the AP. The proportion of POMC cells containing PC1 was significantly higher (P < 0.01) in the 100-107 dGA and 144-147 dGA groups than in the 117-121 dGA and 126-130 dGA groups in both inferior and superior AP. The intensity of the PC1 hybridization signal over POMC-expressing cells was also about 2- to 4-fold greater (P < 0.01) in the inferior compared with the superior region of the fetal AP; the intensity of the PC1 hybridization signal associated with POMC cells remained constant within the AP region and did not change over the gestational ages examined. Hybridization for PC1 was highly variable over regions of AP not hybridizing for POMC, probably due to differences in the level of mRNA for PC1 between phenotypes. Similar to POMC cells, the average hybridization signal for PC1 over non-POMC-hybridizing regions was about 2-fold greater in the inferior vs. superior AP. A weak PC2 hybridization signal was observed over a small number of unidentified phenotypes in the fetal AP at all ages examined; no POMC cells were found to contain PC2 hybridization signal. In the neurointermediate lobe, POMC, PC1, and PC2 were ubiquitously expressed at all ages. Levels of PC1 and PC2 mRNA in the fetal neurointermediate lobe did not change over the period of gestation examined. Immunocytochemical analysis of PC1 and PC2 with ACTH confirmed the pattern of expression and the extent of coexpression observed with in situ hybridization methods. We conclude that both PC1 and PC2 are likely to contribute to POMC processing in the fetal pituitary during the final weeks of gestation.

Structure and function of the ovine type 1 corticotropin releasing factor receptor (CRF1) and a carboxyl-terminal variant.

Corticotropin releasing factor (CRF) is the major neuropeptide regulating the hypothalamo-pituitary-adrenocortical axis in most species. A pituitary receptor for CRF (designated CRF1) belonging to the seven-transmembrane helix, G-protein-coupled receptor superfamily has been cloned for human, rat, mouse and xenopus. Since ovine CRF shares only 84% identity to human/rat CRF (h/rCRF) we postulated that the sheep pituitary CRF1 receptor may have similarly diverged from the rodent and human CRF1. We report the molecular cloning of an ovine pituitary cDNA containing a 1245 bp open reading frame encoding a 415 amino acid sheep CRF1 receptor 78, 86, 94, and 95% homologous to xenopus, chicken, rat, mouse, and human CRF1, respectively. The divergence in primary structure between the sheep CRF1 and the other mammalian CRF1s is primarily localized to the extracellular amino terminal domain of the receptor (18 of 22 divergent residues, ovine vs human CRF1). A variant of the oCRF1 was also isolated (oCRF1var) with 133 bp deleted from nucleotide (nt) 1080 to nt 1213 of the open reading frame (ORF) resulting in a new ORF of 1176 nt predicting a 392 residue CRF1 variant receptor. The 133 bp deletion would cause a frame-shift at residue 358 within the carboxyl-third of the seventh transmembrane domain (TM7) resulting in a shortened cytoplasmic tail with a new amino acid sequence from residue 358 to 392. Scatchard analysis of saturation curves using membrane prepared from Cos 7 cells transfected with oCRF1 or oCRF1var indicated that both wild-type and variant receptors were expressed similarly (number of CRF binding sites) and both bound oCRF with high affinity [oCRF1 (Kd): 2.5 + 1.6 nM; oCRF1var: 5.1 + 2.3 nM]. The non-hydrolyzable GTP analogue (GTPgammaS) lowered the affinity of both wild-type and variant oCRF1 receptors to a similar extent (oCRF1: 18.2 nM; oCRF1var: 22.4 nM). Both wild-type and variant oCRF1 receptors exhibited approximately 10-fold greater selectivity for oCRF and sauvagine compared to h/rCRF or alpha-helical [9-41]oCRF. CRF effectively stimulated the accumulation of cAMP (EC50 = 51 pM) in Cos 7 cells transiently transfected with wild-type but not variant oCRF1 receptor. In Cos 7 cells transfected with oCRF1var, cAMP accumulation was only observed at the highest concentration of oCRF utilized (100 nM). Basal (unstimulated) levels of cAMP in Cos 7 cells transfected with oCRF1var (in the presence of 2 mM IBMX) were approximately 50% lower than for the wild-type oCRF1. Differences in cAMP accumulation could not be attributed to differences in receptor number since total binding sites in the transfected cells were not different between wild-type or variant oCRF1 receptors. Agonist-induced receptor internalization, determined as the percent of total [125I] Tyr0-oCRF bound located in the acid-resistant fraction of transfected Cos 7 cells, increased with time (0-60 min at 37 degrees C) for both wild-type and variant oCRF1. Wild-type CRF1 internalized approximately 2-fold greater percent of total [125I] Tyr0-oCRF bound compared to the variant receptor. In summary, an ovine CRF1 and a CRF1 cytoplasmic tail receptor variant displaying high affinity binding to oCRF as well as selectivity for oCRF vs h/rCRF, were cloned from an adult sheep pituitary cDNA library. GTPgammaS studies indicate that both variant and wild-type receptors couple efficiently to Galphas however, only the wild-type oCRF1 is capable of stimulating cAMP production at physiological levels of CRF. Agonist-induced internalization of the ovine CRF1var is also reduced compared to the wild-type CRF1 receptor. We suggest that the oCRF1var interacts efficiently with Galphas but is unable (post-hormonal binding) to effectively stimulate G-protein activation of adenylate cyclase, indicating that the cytoplasmic tail of the CRF1 can modulate receptor function related to signal transduction. (ABSTRACT TRUNCATED)

A cost-saving algorithm for children hospitalized for status asthmaticus.

OBJECTIVE: To test the ability of an assessment-driven algorithm for treatment of pediatric status asthmaticus to reduce length and cost of hospitalization. DESIGN: Nonrandomized, prospective, controlled trial. SETTING: Tertiary care children's hospital. PATIENTS: Children aged 1 to 18 years hospitalized for status asthmaticus; 104 were treated using the asthma care algorithm (intervention) and 97 using unstructured standard treatment (control). INTERVENTION: Patients were treated using either an assessment-based algorithm or standard care practices. The algorithm group was treated with standard medications (aerosolized albuterol, systemic corticosteroids, epinephrine, ipratropium) administered at a frequency driven by the patient's clinical condition. Specific criteria were outlined for decreasing or augmenting therapy, transferring to intensive care, and discharging to home. A unique patient record containing assessments, algorithm cues, and a treatment record was used. Intervention group patients were interviewed by telephone 1 week after discharge. MAIN OUTCOME MEASURES: Hospital length of stay, cost per hospitalization, relapse rate, protocol adherence. RESULTS: Average hospital stay for intervention patients was significantly shorter than for control patients (2.0 vs 2.9 days, P<.001). Although intervention patients received fewer aerosolized albuterol doses than controls, there was no difference in short-term relapse rate between groups. The intervention saved more than $700 per patient in hospital charges. Adherence to the protocol was excellent, with only 8 variances per patient stay out of more than 150 opportunities. CONCLUSION: An intensive, assessment-driven algorithm for pediatric status asthmaticus significantly reduces hospital length of stay and costs without increasing morbidity.

Fetal sheep pituitary proopiomelanocortin in late gestation: effect of bilateral lesions of the paraventricular nucleus on regional and cellular messenger ribonucleic acid levels.

Previous experiments have clearly indicated that the successful completion of ovine gestation is dependent upon fetal adrenocortical maturation and the associated preterm rise in fetal plasma cortisol. The purposes of this study were to: 1) examine pituitary POMC messenger RNA (mRNA) levels during normal fetal development; and 2) examine the effects of bilateral lesion of the fetal paraventricular nucleus (PVN) on levels and spatial distribution of pituitary POMC mRNA. Pituitary glands were collected from intact fetal sheep of four gestational ages [100-107 days gestational age (dga), n = 8; 117-121 dga, n = 9; 126-130 dga, n = 9; 144-147 dga, n = 8]. Lesions of the PVN (PVN Lx; n = 4) or sham lesions (Sham; n = 5) were performed at 118-122 dga. Pituitary glands from PVN Lx and Sham fetuses were collected at 139-142 dga (term approximately 147 dga). POMC mRNA levels were determined by in situ hybridization. POMC transcript levels were determined by both regional analysis (20x magnification) and analysis of individual corticotropes (400x magnification). There was no difference among gestational age groups in superior anterior pituitary (AP) POMC mRNA levels determined by regional or cellular analysis. POMC mRNA levels were significantly greater in the inferior AP at 144-147 dga, compared with other gestational ages, using regional analysis (P = 0.003) or analysis of individual corticotropes (P < 0.01). POMC mRNA levels in the neurointermediate lobe in 126- to 130-dga fetuses were significantly greater than those in younger fetuses (P = 0.005) but not those in 144- to 147-dga fetuses. There was no difference in POMC mRNA levels in the superior AP between PVN Lx and Sham, using regional analysis or analysis of individual corticotropes. In the inferior AP, there was a significant decrease in POMC mRNA levels in PVN Lx, compared with Sham, using both regional analysis (P < 0.01) and cellular analysis (P < 0.01). There was no difference in POMC mRNA levels in the neurointermediate lobe as the result of bilateral PVN Lx. Our findings support that basal AP POMC mRNA levels are heterogenously distributed in the ovine fetal AP, with POMC mRNA levels in the inferior AP being significantly greater than in superior AP, by 144-147 dga. We further found that the higher POMC mRNA levels in the inferior AP reflect significantly higher corticotrope POMC transcripts and not simply a greater density of corticotropes in this AP region. The increase in POMC mRNA levels at 144-147 dga in the inferior AP seems unrelated to the onset of adrenocortical maturation (at approximately 125-130 dga). Finally, we report that increase in corticotrope POMC transcripts during late gestation in the inferior AP requires an intact PVN.

Consumption of a high fat diet impairs reproductive performance in Sprague-Dawley rats.

Rats made obese by cafeteria feeding have poor reproductive outcomes. To investigate this phenomenon in animals fed a more nutritionally adequate diet, female rats were fed either a high fat (HF) (modified AIN-76A, 35 g fat/100 g diet) or a control (C) (AIN-76A, 5 g fat/100 g diet), diet, beginning at 27 d of age. To assess reproductive performance, rats were studied at d 0, 5 and 18 of pregnancy and on d 3 of lactation. Pregnancy rates were significantly (P < 0.001) lower in the high fat-fed rats than in the control-fed rats (56.4 and 89.1%, respectively). There was no difference between groups in total pregnancy weight gain or the proportion of weight gained during pregnancy that was retained by the dam. High fat-fed dams tended to gain weight more rapidly early in gestation than control-fed dams and then less rapidly than control-fed dams during the last week of gestation. Litter number and pup weight at birth did not differ between groups, but of high fat-fed pups had significantly higher (P < 0.04) mortality rates than pups of control-fed dams (16.5 and 7.7%, respectively) over the first 3 d of life. Control-fed dams experienced the expected reduction (P < 0.05) in plasma insulin concentrations between the end of pregnancy and early lactation, but high fat-fed dams did not. Thus, physiological mechanisms controlling distribution of metabolic fuels may not be functioning properly in high fat-fed dams. Therefore, consuming a high fat diet reduces a rat's capacity to conceive and ability to maintain her litter during the perinatal period.

Naloxone administration does not relieve the inhibition of gonadotropin release in food-restricted, lactating rats.

Lactational anovulation is an important factor in determining birth spacing in women living in developing countries. Therefore, a more comprehensive understanding of the mechanisms involved in the relationships among lactation, nutrition and ovulation is important. This study was designed using the food-restricted, lactating rat to examine whether endogenous opioids might be involved in depressing gonadotropin release. Females were mated after 65 d of age and, beginning on d 42 of life, offered food in unrestricted amounts (control) or were food restricted to 50% of what the controls consumed. On d 15 of lactation, dams were injected with either naloxone hydrochloride (3 mg/kg body weight) or saline and killed 0, 15, 30 or 60 min later. Plasma was analyzed for luteinizing hormone, follicle-stimulating hormone and prolactin. Food restriction decreased plasma concentrations of luteinizing hormone and follicle-stimulating hormone (P < 0.005). Naloxone administration marginally influenced follicle stimulating hormone (P < 0.1), but not luteinizing hormone concentration regardless of diet group. The interaction among diet group, drug group and time of killing was significant for plasma prolactin concentration (P < 0.05). Food restriction lowered prolactin concentrations, but this effect was diminished with increasing time after injection of naloxone. Furthermore, the magnitude of the effect of food restriction was lessened and even reversed with treatment of naloxone. These results indicate that endogenous opioids are not the primary mechanism suppressing luteinizing hormone release in food-restricted lactating rats.

Structure, localization, and molecular phylogeny of a GnRH cDNA from a paracanthopterygian fish, the plainfin midshipman (Porichthys notatus).

Multiple forms of gonadotropin releasing hormone (GnRH) are found within several species of teleost fishes. Within the infradivision Euteleostei, the superorder Paracanthopterygii represents one of the last major groups to be examined with respect to the GnRH mRNA sequence. The plainfin midshipman, Porichthys notatus, is a common member of this superorder which is intermediate between the ancestral euteleost taxa and the more derived Acanthopterygians (percomorphs). The goals of this study were to: (1) determine the cDNA sequence of prepro-GnRH in the plainfin midshipman, (2) address the anatomical localization of midshipman prepro-GnRH gene expression, and (3) perform a cladistic analysis using all currently known cDNA sequences of prepro-GnRH. We report 460 base pair of cDNA sequence containing the entire protein coding region, and 5'- and 3'-untranslated regions. The deduced amino acid sequence indicates that this cDNA encodes a GnRH decapeptide identical in sequence to that originally isolated in salmon (Trp7, leu8 - GnRH). Northern analysis demonstrated transcripts in brain, ovary, and testis (600-700 nucleotides). PCR showed that the ovarian prepro-GnRH was identical to that found in brain. In situ hybridization labeled neurons in the ganglion of the terminal nerve and the preoptic area, forebrain areas previously observed to contain GnRH-like immunoreactivity. Last, a phylogenetic analysis of 18 prepro-GnRH sequences grouped the Paracanthopterygii with the Acanthopterygii. However, this recent clade was distinct from two separate and more ancestral lineages, the Paracanthopterygii (salmonids) and Ostariophysi (represented by catfish).

Prostaglandin synthase activity of fetal sheep cotyledons at 122 days of gestation and term: expression of prostaglandin synthetic capacity in fetal cotyledonary tissue near labor is location-dependent.

An activity assay is described quantification of prostaglandin synthase (PGHS) in sheep placental cotyledon under initial velocity conditions through measurement of the stable product prostaglandin E2 (PGE2). The effects of temperature, time, and substrate concentration on initial reaction velocity, and lipoxygenase and PGHS product formation in cotyledonary tissue, were examined in detail. We used this activity assay to determine whether or not an increase of active PGHS by placental location within the uterus might contribute selected prostaglandins (PG) for the directed initiation of parturition. Sheep cotyledon tissue was collected (n = 6 animals) from the ventral aspect of the uterine body, mid-horn, and horn tip at 122 days of gestation (dga), and from the same locations in the ventral body and horn tip at 142-145 dga (in animals at term but not in labor; n = 4). At 122 dga, there was no increase in active PGHS in cotyledonary tissue from the horn tip, mid-horn, or uterine body. By 142-145 dga, the horn showed significantly (p < 0.01) more enzyme activity than the body. At the same time, production of PGE2, expressed as a percentage of total eicosanoids, had not changed significantly. The development of an increase in PGHS toward the uterine tip implies that variations in regional PG production may contribute to the progression of labor.

Levels of corticotropin-releasing hormone messenger ribonucleic acid (mRNA) in the hypothalamic paraventricular nucleus and proopiomelanocortin mRNA in the anterior pituitary during late gestation in fetal sheep.

CRH regulates POMC gene expression and subsequent ACTH biosynthesis and release. In sheep, the preterm rise in fetal plasma ACTH commences at approximately 125 days gestation (dGA; 147 dGA = term), preceding the initiation of adrenocortical steroidogenesis. We hypothesized that an increase in CRH expression in the hypothalamic paraventricular nucleus (PVN) and POMC expression in the anterior pituitary in the late gestation sheep fetus may precede adrenal cortex maturation. Fetal sheep were obtained at 105-107 (n = 4), 128-130 (n = 5), and 138-140 (n = 4) dGA. Hypothalami were cryosectioned and subjected to in situ hybridization for ovine CRH mRNA. In all dGA groups, expression of CRH mRNA was observed throughout the rostrocaudal extent of the fetal PVN. The midrostral region of the fetal PVN where the dorsal and ventral divisions of the rostral PVN merge to form a single structure was selected for quantification. The number of copies of CRH probe hybridized per micron 3 were determined to estimate the quantity of hybridized CRH mRNA; the mean estimated CRH mRNA copy number per micron 3 midrostral PVN were 0.064 +/- 0.012 (105-107 dGA), 0.237 +/- 0.048 (128-130 dGA), and 0.108 +/- 0.034 (138-140 dGA; mean +/- SEM copies per micron 3 PVN). CRH mRNA signal significantly increased between 105-107 and 128-130 dGA (P < or = 0.05); 138-140 dGA levels of mRNA were not different from either 105-107 or 128-140 dGA levels. Regional variation in CRH mRNA levels were observed within the midrostral PVN between groups; at 138-140 dGA, a population of lateral midrostral PVN neurons maintain CRH mRNA levels greater than 105-107 dGA (P < 0.05), similar to those at 128-130 dGA. Fetal anterior pituitary RNA was subjected to Northern analysis for POMC mRNA. POMC mRNA levels in fetal anterior pituitaries were 14.1 +/- 2.2 (105-107 dGA), 28.9 +/- 10.9 (128-130 dGA), and 43.2 +/- 6 (138-140 dGA; mean +/- SEM arbitrary units). A significant increase (P < or = 0.05) was observed at 138-140 dGA compared to levels at 105-107 dGA. We conclude CRH mRNA levels in the fetal PVN increase coincident with increased POMC gene expression and the late gestation rise in fetal plasma ACTH. We speculate that a neuroendocrine stimulus at the fetal PVN may precipitate increased levels of CRH mRNA, initiating the maturation of the fetal hypothalamic-hypophyseal-adrenal axis, thus inducing the events of labor and delivery in sheep.

Endogenous opioid suppression of release of luteinizing hormone during suckling in postpartum anestrous beef cows.

Beef cows were used to determine if suckling influences release of LH via endogenous opioids at 28 +/- 4 d after parturition. Cows of similar weight and body condition (6.8 +/- .1, 1 = emaciated, 9 = obese) were assigned randomly to five groups (n = 6 to 7): 1) control-suckled/saline (suckled 15 min every 6 hr for 48 hr); 2) control-suckled/naloxone; 3) calf-removal/saline (calf removal for 52 hr); 4) calf-removal/naloxone; and 5) control-suckled/GnRH (Gonadotropin-Releasing Hormone). At 0 hr, saline was administered to all cows. This treatment was continued at 6 hr intervals for 24 hr. Either naloxone (0.5 mg/kg), GnRH (40 ng/kg) or saline was administered to cows in their respective groups every 6 hr during the ensuing 24-hr period in calf-removal groups, or immediately preceding each suckling episode in the control-suckled groups. Blood samples for analysis of luteinizing hormone (LH) were collected at 15-min intervals for 1 hr prior to and 3 hr after treatment at 0, 24, 36 and 48 hr. Cows were observed for estrus twice daily. All cows in the control-suckled/GnRH group released LH (P less than .05) in response to exogenous GnRH, indicating the presence of releasable quantities of the gonadotropin. Mean concentrations of LH were not effected (P greater than .05) by the control-suckled regime. However, calf-removal alone, or in combination with naloxone, increased (P less than .05) mean concentrations of LH by 48 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Implementation of the school nurse practitioner role: barriers and facilitators.

The purpose of this descriptive pilot study was to begin an exploration of the role determinants that facilitate or cause barriers to the implementation of the school nurse practitioner (SNP) role. Utilizing a two-step design, 16 SNPs from different school districts were surveyed to determine if their assignment included doing school physical exams. Thirteen indicated that they were functioning as SNPs. The three "no" districts were matched with three of the "yes" districts. An SNP, a school health administrator and a school physician from each district were interviewed individually using a structured questionnaire. The focus of the questions was on organizational structure of the school health services, indicators of administrative support for SNPs and the assigned function of the SNP. Responses were matched for the "yes" and "no" districts and for the three types of professionals. The major facilitator of SNP role implementation was if the idea had originated with the administrator or physician decision maker. Role change and boundary encroachment were the main barriers identified.