Maturational effects of cortisol on the exocrine abomasum and pancreas in fetal sheep

The role of cortisol in the prenatal development of digestive enzymes in the abomasum (prochymosin and pepsinogen) and pancreas (amylase, trypsin, chymotrypsin) has been investigated in the fetal lamb during late gestation. The abomasum and pancreas were collected from 22 unoperated control fetuses (99-145 days gestation; term, 145 +/- 2 days), from seven pairs of twins infused with either saline or cortisol for five days preceding delivery at 127-133 days, and from four 139-143-day-old fetuses adrenalectomized at 120-123 days. Developmental increases (2-8-fold) occurred in protease concentrations in the fetal abomasum and in amylase and chymotrypsin contents in the fetal pancreas. These increases paralleled the normal prepartum rise in fetal plasma cortisol. In addition, the enzyme values were significantly higher in cortisol-infused than in saline-infused fetuses (with the exception of pancreatic amylase) and were significantly lower in adrenalectomized fetuses than in control fetuses at term. The pH of abomasal fluid remained neutral (pH 6.8-8.0) during late gestation and was not affected by cortisol treatment or adrenalectomy. The results suggest that cortisol stimulates the development of the exocrine abomasum and pancreas in fetal sheep and may, thereby, increase the digestive capacity in neonatal lambs. Compared with the pig, another long-gestation species, the sheep has an early development of gastric pepsinogen but a late development of gastric acidity and pancreatic protease activities.

Fetal and maternal plasma lipids in chronically catheterized mares in late gestation: effects of different nutritional states

The effects of different nutritional states on plasma lipid concentrations have been examined in pregnant mares and their fetuses. Maternal and fetal arterial catheters were inserted into 12 pony mares between 244-303 days' gestation (term 320-360 days) and observations made from 5 days following the insertion of catheters. After recovery from surgery maternal and fetal arterial samples were withdrawn from 7 mares with normal feeding patterns (Group IA), from four of these mares at the end of a 30 h fast and 3 h later following refeeding (Group IB) and six mares who failed to re-establish normal feeding patterns (Group II). The fatty acid concentrations and composition of the plasma free fatty acid (FFA), triacylglycerol and phospholipid fractions were analysed. Maternal FFA, triacylglycerol and phospholipid concentrations were significantly raised in the fasted (Group IB) and under-fed (Group II) mares. Fetal concentrations of FFA and phospholipid increased significantly in the group of under-fed (Group II) mares but not in the fasted (Group IB) mares. In the fetal plasma the proportions of polyunsaturated fatty acids derived from essential fatty acids in the FFA and phospholipid fractions were much higher than those in the mare. In the fasted (IB) and under-fed (II) groups the relative amounts of the polyunsaturated fatty acids in each fraction remained unchanged (P > 0.05). These results show a short fast or prolonged undernutrition result in raised maternal plasma lipid concentrations which in turn can effect the total amount of lipid in the fetal circulation. However any increases in polyunsaturated fatty acids in the fetus (e.g. in Group II) are unlikely to come from the maternal circulation; likely sources of these fatty acids are the placenta or fetal tissues.

Renal function in the chronically cannulated fetal llama: comparison with studies in the ovine fetus

Samples of maternal and fetal plasma, fetal urine, and amniotic fluid were collected from 8 chronically cannulated pregnant llamas, in the last third of gestation. The samples were obtained for up to 18 days post-surgery. Osmolality, sodium (Na), potassium (K), chloride (Cl), and urea were measured on 40 samples collected on days 1, 2, 3, 4-5, 6-7, 8-9, and 10-19. The osmolalities of maternal and fetal plasma, fetal urine and amniotic fluid, averaged over these 7 time periods, were, respectively, 312 +/- 2, 311 +/- 1, 484 +/- 14, and 317 +/- 1 mosmol kg-1. Values are given as mean +/- s.e. The major differences from fetal fluid values in the ovine fetus (from previously published values) were the higher osmolality and urea concentration of llama fetal urine. Urine flow rate measured in 6 fetuses, 4.5-6.5 kg body weight, was 5.8 +/- 0.4 mliter h-1; urea clearance rate was 55.5 +/- 11.8 mliter h-1. Glomerular filtration rate (GFR), measured with 51Cr-EDTA in 5 fetuses on 1-4 occasions, was 111.4 +/- 23.3 mliter h-1. Fractional reabsorptions (FR) of Na, K and Cl were 97.9 +/- 1, 75.9 +/- 13.5 and 97.7 +/- 0.4% respectively. The GFR (25 mliter kg-1 h-1) and urine flow rate (1 mL kg-1 h-1) were less than half and about one-tenth the respective values in ovine fetuses. As Na reabsorption is the major oxygen-consuming activity of the kidney, the llama fetal kidney requires only half the oxygen needed by the ovine fetal kidney to reabsorb the filtered sodium load. The reason for the formation of hypertonic, rather than hypotonic, urine in the fetal llama may be due to both greater morphological maturity of the kidney and the excretion of as yet unidentified osmotically active organic substances.

The effects of thyroid hormones on oxygen and glucose metabolism in the sheep fetus during late gestation

1. The effects of thyroid hormones on fetal metabolism during late gestation were examined by measuring the rates of glucose and oxygen utilization rates in chronically catheterized sheep fetuses made hypothyroid by either fetal thyroidectomy (TX) or hypophysectomy (HX). The values were compared with those in intact fetuses and in thyroxine (T4)-treated TX and HX fetuses. 2. Umbilical O2 uptake expressed on a weight-specific basis was reduced by 20-30% in the hypothyroid fetuses and was restored to normal values when plasma T4 levels were maintained in the TX and HX fetuses by exogenous T4 administration. 3. The low O2 consumption rates of the untreated hypothyroid fetuses were accompanied by fetal growth retardation, an abnormal blood gas status, and in the TX fetuses, by significant reductions in the rates of glucose oxidation, CO2 production from glucose carbon and O2 utilization for glucose oxidation. 4. When T4 levels were maintained in the TX fetuses, these metabolic rates and fetal blood gas status were restored to their normal values. Replacement of T4 also sustained growth in TX but not in HX fetuses. 5. When the data from all fetuses were combined irrespective of treatment, there were significant positive correlations between plasma levels of T4 (but not triiodothyronine (T3)) and the rates of umbilical O2 uptake, glucose oxidation, CO2 production from glucose carbon and O2 utilization for glucose oxidation in the individual fetuses. 6. These findings demonstrate that T4 is a physiological regulator of O2 utilization by the sheep fetus close to term.

Release of lipid from the equine placenta during in vitro incubation

An in vitro incubation technique was used to examine release of lipids from the equine placenta. Placental tissue was obtained at term (n = 5, term = 320-365 days) and earlier in gestation (n = 8, mean = 266 days). Term placentae were incubated at two temperatures, 4 degrees C (control) and 37 degrees C for 2 h. Pre-term placentae were incubated at 37 degrees C with two different concentrations of fatty acid in the medium. Tissues and media were analysed for their lipid concentrations. Term and pre-term placentae released free fatty acid (FFA) and phospholipid into the incubation medium during incubation at 37 degrees C. Long chain polyunsaturated fatty acids derived from the essential fatty acids were released into the media. The fatty acid profiles of the lipids released during incubation more closely resembled those of fetal plasma than maternal plasma lipids as measured in previous studies. These data are consistent with the view that the equine placenta is a source of both FFA and phospholipid for the fetus and that the placenta may provide long chain polyunsaturated fatty acids for the fetal foal.

The technique of pleurodesis

Pleurodesis may be indicated for pleural effusions (with careful patient evaluation) or recurrent pneumothoraces. It is contraindicated if tube thoracostomy fails to reexpand the lung and, possibly, if patients are candidates for lung transplantation or have congestive heart failure. We perform pleurodesis through an indwelling chest tube (alternative methods are thoracoscopy and thoracotomy). Common sclerosants include talc, doxycycline, minocycline, and bleomycin. Intrapleural administration of lidocaine may control pain, but injections of morphine or meperidine almost always are needed.

Prepartum adrenocortical maturation in the fetal foal: responses to ACTH

The present study was carried out on 19 chronically catheterized mares and fetuses in late gestation (term > 320 days). In six animals which were monitored up to the time of delivery of a live foal, plasma and amniotic fluid cortisol concentrations remained low until 4-5 days before parturition when there was a rapid, significant rise (P < 0.05) which was not accompanied by any corresponding changes in maternal plasma cortisol. Circulating fetal ACTH concentrations became more variable close to delivery and ANOVA revealed no significant increases during this critical period, although a negative correlation between plasma ACTH and time to delivery was observed (P < 0.05). Tests on fetal adrenal responsiveness to exogenous ACTH1-24 were carried out on ten animals. Before 295 days of gestation no significant increases in fetal plasma cortisol above its basal level of 20-30 nmol/l could be elicited by ACTH, administered as a single i.v. injection (1-2 micrograms/kg). By 304 +/- 3 days (mean +/- S.E.M.) small but significant (P < 0.05) increments in plasma cortisol were detected after ACTH, while in the oldest group (313 +/- 2 days) significant (P < 0.01) 50-60% increments were seen throughout the test period (2 h). Only one fetus was tested within 3 days of delivery and here a fourfold rise in plasma cortisol was evoked by ACTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental regulation of the porcine exocrine pancreas by glucocorticoids

The possible role of cortisol in development of the exocrine pancreas was investigated. In the first study, fetal pigs were removed from the uterus by caesarean section (pentobarbitone anesthesia) and the pancreas collected from 51 69 to 109-day-old fetuses (term = 114 +/- 2 days). Of these, 15 88 to 90-day-old fetuses had been infused subcutaneously for 6 days with either saline, adrenocorticotropic hormone or cortisol (osmotic mini-pumps implanted at 82-84 days). The pancreas was also removed from eight newborn pigs. Quantitative enzyme analysis showed that amylase and trypsin activities per milligram pancreatic protein increased toward term, correlated positively with fetal plasma cortisol (p < 0.01) and were stimulated by cortisol infusion (p < 0.05). In the second study, pigs were delivered by caesarean section 2-3 days before term (to circumvent the neonatal cortisol surge) and injected intramuscularly with saline (n = 11), metyrapone (an inhibitor of cortisol synthesis, n = 12), adrenocorticotropic hormone (n = 14) or cortisol acetate (n = 6) during the postnatal period. At 6-7 days of age, adrenocorticotropic hormone- and cortisol acetate-treated pigs had higher concentrations of amylase and trypsin in pancreas than metyrapone-treated pigs. The values in saline-injected pigs were intermediate. By gel electrophoresis and subsequent incubation with enzyme substrates, protease E, chymotrypsin C, and cathodic trypsin were first detected at 6-7 days of age, and the activities (semiquantitative densitometry) appeared lower in metyrapone-treated pigs than in pigs from other treatment groups. The results indicate that glucocorticoids stimulate the perinatal development of pancreatic enzymes in the pig.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of parathyroid hormone-related protein in calcium homeostasis in the fetal pig

The concentrations of plasma parathyroid hormone-like bioactivity and parathyroid hormone-related protein (1-86) (PTHrP) immunoreactivity were both higher in fetal pigs than in their mothers during the last 3 weeks of gestation. Both activities changed inversely with alterations in the plasma ionized calcium concentration. The data suggest that PTHrP may have a role in calcium homeostasis in the fetal pig, similar to its postulated role in sheep in the stimulation of calcium transport across the placenta.

Blood amino acids in the pregnant mare and fetus: the effects of maternal fasting and intrafetal insulin

Blood amino acids were measured in twelve chronically catheterized mares and fetuses between 250 and 310 days gestation. The concentrations of the majority of individual amino acids were similar in maternal and fetal arterial blood and no gestational changes were detected. Only methionine, phosphoserine, 3-methyl-histidine and glutamine were consistently higher in the fetus than the mare, whilst certain other amino acids were higher in the maternal blood. Fasting the mares for 36 h led to significant falls in plasma glucose and rises in urea and maternal free fatty acids (FFA). Small but significant decreases in a few amino acids were seen in both fetus and mother, with an overall amino acid fall of 15% in the fetus and 13% in the mare. Virtually all amino acids had risen to basal values by 6 h after feeding. Intrafetal insulin (1 i.u./kg I.V.) as a bolus caused a more dramatic fall in fetal glucose than fasting, with no change in the mare. There were also rapid decreases in many amino acids by 30 min post-insulin and by 2 h all but five amino acids had fallen significantly. There was a drop in total fetal blood amino acids of 29%. These findings show that, in contrast to most other species studied, there is no overall feto-maternal gradient in blood amino acids in the mare, and that fasting leads to small falls in amino acid concentration, whereas intrafetal insulin induces a severe hypoglycaemia with dramatic decreases in almost all amino acids and no change in urea, suggesting a direct anabolic effect of insulin on fetal tissues.

Secretion of acid, gastrin, and cobalamin-binding proteins by the fetal pig stomach: developmental regulation by cortisol

The role of cortisol in the development of gastric function was investigated in the fetal pig. Pregnant sows (term = 114 +/- 2 days, n = 10) were anaesthetized (pentobarbitone) and osmotic minipumps containing either saline or cortisol inserted subcutaneously into fetuses at 82-84 (n = 11) or 91-96 (n = 14) days gestation. Six days later the infused pigs were removed by Caesarean section and the stomach and its contents collected for analysis. Samples were also obtained from unoperated (control) fetal pigs (n = 51) removed under anaesthesia at intervals from 70 days gestation until term. The concentrations of acid in gastric fluid, gastrin in plasma and antral tissue (bioactive as well as precursor forms), and cobalamin(CBL)-binding proteins in fundic tissue were low in control pigs until 100 days gestation. During the last 2 weeks before term, large increases occurred in gastric fluid acidity (from pH 6-7 to pH 3 at birth), plasma amidated gastrin (from 10 to 90 pM) and CBL-binding protein concentration (from 10 to 80 pmol (g fundus)-1). These changes occurred in parallel with a surge in plasma cortisol (from 20 to 200 ng ml-1). Immature fetuses infused with cortisol had significantly higher gastric acidity, plasma amidated gastrin, and concentration of CBL-binding proteins than the corresponding control fetuses (P < 0.05). Across age and treatment groups, significant correlations were found between log10 plasma cortisol values and the above parameters (r = 0.59-0.76, P < 0.01). The results suggest that endogenous cortisol secretion stimulates the secretion of gastric acid, gastrin and CBL-binding proteins in the prenatal period of the pig.

Adrenocortical stimulation of stomach development in the prenatal pig

Development of the porcine gastric proteases (chymosin, pepsin A, B and C) has been studied in the fetal pig in the last third of gestation (term 115 days). The possibility that the prepartum rise in circulating cortisol is involved in gastric maturation was investigated by infusing immature fetuses with cortisol (osmotic minipumps implanted at 82-90 days of gestation). Concentrations of prochymosin in fundic tissue and stomach contents increased before term, correlated positively with log10 plasma cortisol values (r = 0.68-0.76, p < 0.001), and were stimulated by cortisol infusion (p < 0.001). The pH of stomach contents decreased (from pH 7 to 3), correlated negatively with log10 plasma cortisol values (r = -0.69, p < 0.001), and was reduced by cortisol infusion (p < 0.05). Only trace amounts of pepsinogens could be detected in fetal pigs. By immunohistochemistry, it was shown that cortisol increased the number and distribution of prochymosin-containing cells in the fundic gland. Stimulating effects were also observed for the small populations of pepsinogen-reactive cells present in some of the fetal pigs. The results suggest that endogenous cortisol stimulates the rise in prochymosin synthesis and secretion together with increased gastric acidity in the prenatal period of the pig.

Preoperative diagnosis of a forearm peripheral schwannoma

A 34-year-old man had a right distal forearm mass of unknown etiology for 6 years. Magnetic resonance imaging showed a tumor in continuity with the median nerve. Fine-needle biopsy revealed it to be a schwannoma. Surgical excision was performed by separating the nerve fascicles from the tumor. The patient was asymptomatic at 12-month follow-up.

Techniques for chest tube insertion and pleurodesis. An updated look at two common procedures

Chest tube insertion is warranted for drainage of large exudative pleural effusions, empyemas, hemothoraces, or chylothoraces, and for some pneumothoraces or parapneumonic effusions. Chest tubes may also be used to instill sclerosing agents to prevent recurrent malignant effusions or pneumothorax. There are no absolute contraindications to tube thoracostomy; however, if time allows, effort should be made to correct any coexisting hemorrhagic disorders before the procedure is performed. Pleurodesis may be contraindicated in patients who are expected to undergo lung surgery. The incisional method is safest for chest tube insertion and pleurodesis; bear in mind, however, that some patients with pneumothorax may be better treated with small-caliber drainage.

Insulin-like growth factor-II messenger ribonucleic acid expression in fetal tissues of the sheep during late gestation: effects of cortisol

Using RNase protection analysis, insulin-like growth factor-II (IGF-II) mRNA levels were measured in various tissues from fetal sheep during late gestation (term, 146 +/- 2 days) and after experimental manipulation of fetal plasma cortisol levels. No gestational trend in IGF-II mRNA levels was observed in the fetal lung, kidney, or skeletal muscle. However, in the fetal liver, there was a marked decline in IGF-II mRNA abundance immediately before term, which closely paralleled the normal prepartum surge in fetal plasma cortisol. This decrease in hepatic IGF-II mRNA levels toward term was prevented when the cortisol surge was abolished by fetal adrenalectomy and was stimulated prematurely in fetuses younger than 130 days by exogenous infusion of cortisol. Hepatic and renal IGF-II mRNA abundances were also reduced when fetal cortisol levels were raised endogenously by maternal fasting in late gestation. Muscle IGF-II mRNA levels were reduced by fetal cortisol infusion, but not by maternal fasting, and were higher in adrenalectomized than in intact fetuses in late gestation. No change in IGF-II mRNA levels were observed in the fetal lung in response to altering the fetal cortisol level either exogenously or endogenously. When the data from all fetuses were combined regardless of treatment or gestational age, there was a significant inverse correlation between the plasma cortisol level in utero and IGF-II mRNA abundance in the fetal liver (P < 0.001), but not in any of the other fetal tissues studied. These findings show that cortisol suppresses IGF-II gene expression in the liver of the sheep fetus and indicate that the developmental change in hepatic IGF status toward term may be due to the prepartum cortisol surge.

The effects of cortisol on hepatic and renal gluconeogenic enzyme activities in the sheep fetus during late gestation

The effects of cortisol on hepatic and renal gluconeogenic enzyme activities were investigated in sheep fetuses during late gestation and after experimental manipulation of plasma cortisol levels by fetal adrenalectomy and exogenous infusion of cortisol. Hepatic and renal gluconeogenic enzyme activities increased with increasing gestational age in parallel with the normal rise in fetal cortisol levels towards term (146 +/- 2 days). For the majority of enzymes this increase in activity towards term was prevented when the prepartum cortisol surge was abolished by fetal adrenalectomy and stimulated prematurely in fetuses younger than 130 days by exogenous infusion of cortisol. When the data from all the fetuses were combined irrespective of treatment or gestational age, there were significant positive correlations between the log plasma cortisol concentration in utero and the activities of glucose-6-phosphatase, fructose diphosphatase, phosphoenolpyruvate carboxykinase and aspartate transaminase in the fetal liver and kidney, and pyruvate carboxylase in the fetal liver but not in the kidney. No correlation was observed between log plasma cortisol and alanine aminotransferase activity in either fetal liver or kidney. These findings show that cortisol is a physiological regulator of most of the fetal gluconeogenic enzymes and enhances the glucogenic capacity of the sheep fetus during late gestation.

CT detection of occult pneumothorax in multiple trauma patients

Chest injuries are the cause of death in 25% of trauma fatalities, and a major contributing factor in an additional 50%. Pneumothorax, the second most common chest injury, may often be initially overlooked. Administration of anesthesia and mechanical ventilation may produce enlargement of a pneumothorax and clinical deterioration. We reviewed 90 trauma patients who had been admitted with a diagnosis of pneumothorax or who had developed pneumothoraces after hospital admission. In 35 cases (38.8%), initial supine chest x-ray study failed to detect a pneumothorax, and the diagnosis was made on CT scan of the chest or abdomen performed within 2 hours of admission. In 15 of these cases (42.8%), identification of the pneumothorax on CT scan resulted in alterations in management, including chest tube placement in 10 patients and intensified monitoring in 5 patients. Failure to identify pneumothoraces in trauma patients may lead to deterioration and significant complications in patients requiring anesthesia or mechanical ventilation. CT scan may facilitate identification in these cases.

Prostaglandin-induced antral hyperplasia in neonates: clinical experience and dose-response characteristics

Antral hyperplasia (AH) induced by prostaglandins (PG) has been described by us recently in 5 infants with cyanotic heart disease receiving the drug. The purpose of the present study was to analyze 14 infants diagnosed as having AH either sonographically or pathologically in an attempt to characterize the dose-response characteristics of this adverse drug reaction, its clinical course and its optimal management. Infants with AH exhibiting large gastric aspirates have received a significantly lower cumulative dose (1,633 +/- 1,266 micrograms/kg) than those presented also with a palpable mass (3,458 +/- 1,703 micrograms/kg), (p < 0.01). While in general there is a dose-related clinical toxicity, variability in the location of the hyperplasia can explain cases of no apparent obstruction despite large cumulative doses of PG. In asymptomatic cases the antral hyperplasia, although visualized, it did not result in gastric outlet obstruction. In all cases followed by us to date, discontinuation of the PG has resulted in resolution of the clinical and sonographic findings. Nasojejunal tube was successfully attempted in several cases, preventing surgery in these very-high-risk infants.

HIV seroprevalence among homeless patients admitted to a psychiatric inpatient unit

OBJECTIVE

This study was conducted to determine the seroprevalence of HIV-1 antibodies among hospitalized homeless mentally ill patients.

METHOD

From December 1989 through May 1991 the authors collected discard blood samples from patients consecutively admitted to a psychiatric unit designated for the care of severely mentally ill persons removed from the streets of New York City. The blood samples were tested for HIV-1 antibodies, and the results were analyzed for associations with age, gender, ethnicity, male homosexual activity, and use of injected drugs.

RESULTS

The HIV seroprevalence was 6.4% (13 of 203 samples). Patients between ages 18 and 39 accounted for 51.2% of the admissions and 84.6% of the 13 positive results, a seroprevalence of 10.6% for this subsample. Patients under age 40 were more than six times as likely to test positive for HIV antibodies as those 40 or over. Ethnicity did not predict seropositivity. Women were as likely as men to be infected. Although clinicians had noted high-risk behavior on the charts for only three (23.1%) of the 13 positive cases, a recorded history of use of injected drugs was associated with a 6.5-fold greater risk of HIV seropositivity.

CONCLUSIONS

One in every 16 patients admitted to the special unit was HIV positive. Age under 40 and use of injected drugs were strongly associated with seropositivity. Because information on high-risk behavior was infrequent, the reasons for younger patients' greater risk are unclear. The homeless mentally ill require outreach efforts to reduce the risk of acquiring or transmitting HIV.

Intravenous catheterisation of foetus and mare in late pregnancy: management and respiratory, circulatory and metabolic effects

The uterine and umbilical vessels of 12 pregnant ponies were catheterised to study foetal metabolism. The effects of this procedure on maternal and foetal cardiovascular, respiratory, metabolic and adrenocortical activity were monitored during and after surgery. Premedication with acepromazine-butorphanol-detomidine was followed by induction of anaesthesia with detomidine and ketamine and maintenance, using mechanical ventilation, with halothane in oxygen and nitrous oxide. Mean maternal arterial blood pressure was greater than 70 mmHg during anaesthesia and arterial oxygen tension remained over 100 mmHg. The foetuses were adequately oxygenated but were hypercapnic and lactic acidaemic. Most maternal and foetal blood gases and metabolites had returned to normal by 24 h, although foetal plasma lactate fell more slowly. The maternal adrenocortical discharge was less severe than reported previously and plasma cortisol had fallen to basal levels by 48 h after surgery. Foetal plasma cortisol remained low and did not change during or after surgery. Arterio-venous metabolite and gas tension differences across the uterine and umbilical circulations were slightly greater at operation than in the recovery period, suggesting that uteroplacental perfusion may have been impaired during surgery. Post-operative recovery of the mare and foetus was satisfactory and subsequent problems associated with the foetal catheters were not related to the anaesthesia or surgery.

Effect of cortisol infusion on the pituitary-adrenal axis of the hypothalamo-pituitary-disconnected fetal sheep

In order to determine whether cortisol acts directly at the level of the fetal pituitary to promote pars distalis corticotroph maturation, we have infused cortisol into the hypothalamo-pituitary-disconnected (HPD) fetal sheep from 111 to 117 days of gestation. In this study we have measured fetal plasma cortisol and immunoreactive adrenocorticotrophic hormone (ir-ACTH) concentrations between 105 and 116 days of gestation, and we have determined the proportions of adult- and fetal-type corticotrophs in the pars distalis of catheter control fetuses and in HPD fetuses infused with either saline (HPD+SAL) or cortisol (2 mg/day; HPD+F). The fetal plasma cortisol concentrations did not change significantly following HPD. The mean fetal plasma cortisol concentration between 113 and 116 days was threefold higher in the HPD+F fetuses than that measured in HPD fetuses. Following HPD, fetal plasma ir-ACTH concentrations were significantly higher than in catheter control fetuses. Despite the significant elevation in plasma cortisol concentrations in HPD+F fetuses between 113 and 116 days, plasma ir-ACTH concentrations were not different in these fetuses from HPD fetuses infused with saline. At 117 days of gestation in HPD+F fetuses, the proportion of fetal-type corticotrophs in the pars distalis was significantly less than in the HPD+SAL fetuses; however, there was no significant change in the proportion of adult-type corticotrophs in the pars distalis following cortisol infusion. We have shown that cortisol has a direct trophic effect on the maturation of the pars distalis corticotrophs; however, the full maturation of these cells requires an intact hypothalamo-pituitary axis. These findings demonstrate the importance of the fetal hypothalamus in anterior pituitary corticotroph maturation during the last third of gestation.

The development of gluconeogenic enzymes in the liver and kidney of fetal and newborn foals

The activities of glucose-6-phosphatase (G6P), fructose diphosphatase, phosphoenolpyruvate carboxykinase (PEPCK), aspartate and alanine transferases were measured in liver and kidney of fetal foals between 100-318 days of gestation (term approximately 335 days) and during the immediate postnatal period (0-48 h after birth). All 5 enzymes could be detected in the fetal liver and kidney at the youngest gestational age studied. Mean fetal activities were lower than those observed in their mothers and showed no change with gestational age for the majority of enzymes studied. However, renal PEPCK and renal and hepatic G6P did increase towards term. At birth, hepatic and renal activities of these two enzymes were higher than those found in late gestation or in the adult animals. There was no apparent change in the activities of any of the other enzymes at birth. In late gestation (80-90% gestation), the activities of G6P and PEPCK in the foal were low compared to those in other species at the same stage of gestation. Similarly, the perinatal increase in enzyme activity occurred closer to term in the foal than in most other species. These observations indicate that maturation of glucogenic capacity occurs relatively late in the fetal foal and suggests that this process may be dependent on the prepartum rise in fetal cortisol as occurs in other species.

Temperament and interactive effects: mothers and infants in a teaching situation

Temperament is a theoretical concept used to understand individual's behavioral styles. In this study, temperament was measured in 13-month-old infants (N = 51) and their mothers, who were also observed together in a teaching situation. The purpose of the study was to determine the relationships between maternal and infant temperaments and interactive behaviors in the teaching situation. Mothers were given 10 minutes to teach infants four tasks designed to assess qualitative aspects of the interaction. In general, the interaction between mother and infant had a synchronous quality that was influenced by, but largely independent of, the temperamental characteristics of mother and infant. Responsive maternal teaching behaviors were significantly related to positive infant affect during teaching. Weak relationships were found between the temperament variables and interactive behaviors in the teaching situation. When mothers and infants were matched on temperament characteristics, no effects of matching temperaments on interactive behaviors in the teaching situation were found. These findings suggest that mothers are able to adjust their behaviors to compensate for their infant's temperament. Based on these data, nurses can focus on the dynamics of the interactions themselves and avoid making judgments based on temperament alone when evaluating mother-infant relationships.

The effects of glycemia on breathing movements and plasma prostaglandin E concentrations in the sheep fetus

OBJECTIVE

The purpose of this study was to determine the roles of fetal plasma glucose and prostaglandin E in controlling fetal breathing movements.

STUDY DESIGN

Five late pregnant ewes with catheterized twin fetuses were fasted for 48 hours; one fetus was kept normoglycemic (by glucose infusion) and the other allowed to become hypoglycemic during this period. Fetal breathing movement and fetal and maternal plasma prostaglandin E and glucose concentrations were measured throughout. Data were analyzed by paired and unpaired t tests.

RESULTS

The mean incidence of fetal breathing movement was significantly greater in the normoglycemic fetuses that in the hypoglycemic twins at the end of the fast (p less than 0.05), whereas plasma prostaglandin E levels increased significantly (p less than 0.05) and to the same extent in both groups of fetuses.

CONCLUSION

The reduced incidence of ovine fetal breathing movement that occurs during maternal fasting appears to be primarily caused by fetal hypoglycemia and does not directly involve changes in fetal plasma prostaglandin E.

Postoperative course after sufentanil or fentanyl anesthesia for coronary artery surgery

Postoperative hemodynamic effects were compared in 50 patients randomly selected to receive either sufentanil, 25 micrograms/kg, or fentanyl, 100 micrograms/kg, anesthesia for coronary artery bypass grafting. The two groups exhibited similar patient demographics; dose of premedicants and muscle relaxants; and use of inhalation agents. Values for 15 hemodynamic variables were recorded at baseline and at six postoperative times. The times to awakening, response to verbal commands, and extubation were also noted. Patients who received sufentanil had a more stable course, with higher cardiac outputs, lower systemic vascular resistances, and a lower incidence of hypertension. Postoperatively, the two groups had similar values for time to awakening, response to verbal commands, and extubation. Elimination half-lives differed significantly: 554 +/- 91 minutes (fentanyl) versus 277 +/- 60 minutes (sufentanil). Serum concentrations of both decreased linearly. The added advantages of postoperative hemodynamic stability could be important in the choice of anesthetic.

Effect of adrenalectomy or long term cortisol or adrenocorticotropin (ACTH)-releasing factor infusion on the concentration and molecular weight distribution of ACTH in fetal sheep plasma

It is unclear whether the maturation of corticotrophs from the fetal to the adult type in the fetal sheep pituitary in late gestation is associated with changes in the sensitivity of the fetal pituitary to corticotrophic secretagogues and in the form of ACTH-containing peptides (IR-ACTH) secreted into the circulation. The maturation of the pituitary corticotroph population is known to be accelerated by intrafetal cortisol infusion and delayed by bilateral fetal adrenalectomy. We have therefore investigated the mol wt profile of IR-ACTH present in fetal sheep plasma from 110 days gestation until term (147 +/- 3 days) and determined whether intrafetal cortisol infusion between 105-117 days (2.5 mg cortisol/day), or bilateral fetal adrenalectomy can alter the mol wt profile of IR-ACTH in fetal sheep plasma. We have also investigated whether prior exposure to cortisol alters the subsequent responsiveness of the fetal pituitary to a long term infusion of ovine (o) CRF (10 micrograms oCRF/day). In the control group, the proportion of IR-ACTH which eluted in the low-mol wt (LMW) range (i.e. less than 12K) was significantly higher between 121-125 days (43.9 +/- 4.2%) than between 126-139 days (26.8 +/- 9.3%) but not different to that after 140 days gestation (29.9 +/- 5.5%). Between 110-117 days, cortisol infusion had no effect on the proportion of IR-ACTH in the LMW range (43.9 +/- 5.7%, saline infused; 44.1 +/- 2.4%, cortisol infused). Between 121-125 days, the proportion of IR-ACTH in the LMW range in the CRF-infused groups (with or without prior exposure to cortisol) was significantly lower (27.4 +/- 2.1%) than in the saline-infused control group. In contrast, after fetal adrenalectomy, the proportion of IR-ACTH in the LMW range between 126-139 days was significantly higher (48.0 +/- 6.7%) than in intact control animals (23.8 +/- 3.5%). We conclude that the change in the mol wt profile of IR-ACTH in fetal plasma after 125 days may be a consequence of changes in the morphological and/or functional characteristics of the corticotrophic cells in the fetal pituitary. Infusion of oCRF appears to accelerate the normal maturation of the fetal pituitary-adrenal relationship, and oCRF acting either directly or via secretion of cortisol may play a role in the posttranslational processing of POMC in the fetal sheep pituitary after 125 days gestation.

The effect of hypothalamo-pituitary disconnection on the functional and morphologic development of the pituitary-adrenal axis in the fetal sheep in the last third of gestation

We have investigated the effect of hypothalamo-pituitary disconnection (HPD) on the maturation of basal ir-ACTH and cortisol concentrations in fetal sheep plasma, and on the development of the anterior pituitary corticotroph population in the last third of gestation. After HPD, fetal plasma ir-ACTH concentrations were significantly elevated, and continued to rise with increasing gestational age. However, despite elevated ir-ACTH concentrations, there was no increase in fetal plasma cortisol concentrations, and parturition was delayed for at least 8 days beyond normal term. Furthermore, HPD resulted in a significant disruption of the maturation of the pars distalis corticotrophs. We also examined the change in fetal plasma concentrations of ir-ACTH and cortisol to exogenous CRF after HPD. There was a significant increase in plasma ir-ACTH in response to CRF administration in the HPD fetuses, which was qualitatively similar to that observed in sham-operated fetuses. In contrast, the plasma cortisol response was less in HPD fetuses when compared to that in sham-operated fetuses. The results of this study demonstrate that ir-ACTH secretion is not maintained by the fetal hypothalamus in the last third of gestation, and that ir-ACTH secretion is tonically inhibited by the hypothalamus during this time. The disconnection of the pituitary from the hypothalamus disrupts the maturation of the pituitary-adrenal axis, thus demonstrating the fundamental importance of the hypothalamo-pituitary axis in the normal maturational cascade which culminates in birth in this species.

Respiratory and non-respiratory thoracic movements in the fetal pig

The aim of this study was to characterize the pre-natal activity of the respiratory muscles in a non-ruminant, the pig. Tracheal pressure was recorded from 11 unanaesthetized fetal pigs in utero during late gestation in 9 sows. Two types of inspiratory effort occurred episodically in each fetus during each recording period. Episodes of breathing movements lasted 8.6 +/- 1.1 min and their overall incidence was 41.1 +/- 3.4% of recording time. The mean amplitude of the respiratory efforts was 7.6 +/- 1.1 mmHg and the mean inspiratory time was 0.8 +/- 0.1 s. Episodes of non-respiratory inspiratory efforts, considered to be fetal hiccups, lasted 5.6 +/- 0.8 min. Individual hiccups had a duration of 150-200 msec, a mean amplitude of 41.4 +/- 2.4 mmHg and a mean frequency, during episodes, of 21.9 +/- 2.0 min-1. In contrast to fetal breathing movements, hiccups appeared to be stereotyped events. It is concluded that, in common with other ruminant and non-ruminant species, two types of inspiratory effort occur in the fetal pig. Fetal hiccups, which have been observed in non-ruminant species, may be analogous to deep inspiratory efforts in the sheep fetus. The stimulus for, and function of, fetal hiccupping remain to be determined.

Physiological and pathological influences on sheep blood plasma amine oxidase: effect of pregnancy and experimental alloxan-induced diabetes mellitus

A copper-containing amine oxidase is present in sheep blood plasma and has a high capacity to deaminate spermine and spermidine. The physiological function of this enzyme remains to be determined. Sheep blood plasma amine oxidase (SPAO) was measured by its ability to deaminate spermidine (700 microM) using a peroxidase-linked colorimetric assay developed for microtitre plates. SPAO activity has been studied in a group of Welsh Mountain sheep with experimental alloxan-induced diabetes. This resulted in an increase in SPAO activity which reached a peak of 70 days after alloxan treatment (60 per cent increase). This change could be seen in both pregnant and non-pregnant diabetic sheep. In normal pregnant ewes, SPAO activity remained stable for the first 100 days of pregnancy but declined by 50 per cent in the last month of pregnancy. Together, these findings suggest that SPAO activity is controlled by hormonal influences. This sensitive and convenient assay method could provide clues as to the physiological significance of SPAO and may be a useful clinical chemical indicator in the sheep.

Effects of tutors with subject expertise on the problem-based tutorial process

With the increased interest in problem-based, small-group learning in medical education, a debate has arisen about whether the tutor should be an expert in the subject under discussion. This 1988 study at Harvard Medical School demonstrates that tutors' expertise has important effects on the process of discussion in a problem-based tutorial. In comparing discussions of subjects in which the tutors described themselves as expert with those in which they did not, the authors found that the tutors with expertise tended to take a more directive role in tutorials: they spoke more often and for longer periods, provided more direct answers to the students' questions, and suggested more of the topics for discussion. Tutor-to-student exchanges predominated, with less student-to-student discussion. These effects endanger an important goal of problem-based learning: the development of students' skills in active, self-directed learning.

Is stockless/JIT right for your organization? It wasn't for ours

The authors, investigating the feasibility of a stockless/JIT inventory management system in their hospital, developed a cost analysis model comparing the new system to their current system. This article presents this cost model and their conclusions for their institution.

Induction of labour in sheep by inhibition of 3-beta hydroxysteroid dehydrogenase: role of the fetal adrenal

In sheep parturition may be induced within 33 h in late gestation by inhibiting progesterone production with the 3 beta hydroxysteroid dehydrogenase inhibitor Epostane. Its effect has now been investigated in ewes carrying adrenalectomised (n = 5), hypophysectomised (n = 4) or intact (n = 5) fetuses to determine the role of the fetal adrenal during this type of maternally-induced delivery. Epostane was infused i.v. (1.5 mg/kg) into each group of ewes at 137-156 days gestation. Fetus and mother were sampled from the time of administration until delivery. Measurements of plasma ACTH, cortisol, progesterone and PGF2 alpha metabolite (PGFM) were made and intrauterine pressure was monitored. Epostane induced delivery significantly later in the adrenalectomised (44 h) and hypophysectomised (52 h) animals compared with the controls (33 h). The drop in maternal plasma progesterone was similar in all 3 groups, but the subsequent increases in arterial and uterine venous PGFM were smaller in the adrenalectomised and hypophysectomised ewes than in the controls. The large escalation in fetal plasma cortisol before birth in controls was absent in adrenalectomised and hypophysectomised fetuses. The slight rises in plasma cortisol observed in the latter from about 24 h after Epostane, were related to the concomitant increases in maternal plasma levels (r = 0.76, P less than 0.01). No fetuses became hypoxic or acidotic during the period of induction despite the prolonged labour of hypophysectomised and adrenalectomised fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatal left ventricular perforation following balloon mitral valvuloplasty

Left ventricular perforation following a balloon mitral valvuloplasty is a rare complication. This paper reports morphological findings in such a case that was fatal. Cardiac tamponade was suspected clinically, but could not be confirmed or treated because of extensive anterior pericardial adhesions related to a previous closed mitral commissurotomy.

Proopiomelanocortin messenger RNA levels are increased in the anterior pituitary of the sheep fetus after adrenalectomy in late gestation

We have investigated the effect of bilateral adrenalectomy at 116-119 days' gestation on the levels of the messenger (m) RNA for proopiomelanocortin (POMC) in the anterior pituitary of the fetal sheep and in the ovine placentome during late gestation (134-136 days' gestation). After fetal adrenalectomy there was a significant (p less than 0.001) and sustained increase in circulating ACTH concentrations in the adrenalectomised group (1,838 +/- 155 ng/l at 130-136 days) when compared with the intact control group (131 +/- 25 ng/l at 130-136 days). The mean levels of POMCmRNA relative to 18S RNA were also significantly higher (p less than 0.001) in the adrenalectomised fetal sheep pituitaries (2.8 +/- 0.12; n = 4) than in the intact/control fetal sheep pituitaries (1.31 +/- 0.13; n = 4). In contrast to the findings in the anterior pituitary, POMCmRNA was not detected in RNA extracted from the placentomes of either the adrenalectomised or intact fetal sheep. There was also a significant arteriovenous difference in ACTH concentrations in the umbilical circulation in both adrenalectomised and intact fetal sheep at 134-136 days' gestation. This study demonstrates therefore that the fetal adrenals act to suppress POMCmRNA levels in late gestation and also that the increase in circulating ACTH after adrenalectomy originates from the pituitary and not the placentome.

Endocrine regulation of tissue glucose-6-phosphatase activity in the fetal sheep during late gestation

Endocrine regulation of tissue glucose-6-phosphatase activity in utero was examined by measuring enzyme levels in liver and kidneys of fetal sheep during the second half of gestation and after experimental manipulation of fetal plasma cortisol and insulin levels. Tissue glucose-6-phosphatase activities increased toward term in parallel with the rise in fetal plasma cortisol. At birth, the activities were significantly higher than in utero, but significantly less than in adult nonpregnant sheep. Fetal hypophysectomy lowered fetal plasma cortisol and reduced hepatic and renal glucose-6-phosphatase activities compared with those in intact fetuses near term. Conversely, intrafetal cortisol infusion raised fetal plasma cortisol and significantly increased tissue glucose-6-phosphatase activity to values similar to those in older fetuses. When the data from these groups of fetuses and the newborn lambs were combined, there was a significant positive correlation between the plasma cortisol level and the glucose-6-phosphatase activity in both liver and kidney. Fetal hypoinsulinemia was induced by fasting the ewe for 48 h and by fetal pancreatectomy. Fetal hepatic and renal glucose-6-phosphatase activities were higher in fasted than in fed animals, while pancreatectomy had little apparent effect on enzyme activity in either tissue. However, when differences in plasma cortisol were taken into account, hepatic, but not renal, glucose-6-phosphatase activities were higher in both groups of hypoinsulinemic fetuses than would have been observed in normoinsulinemic animals with a similar plasma cortisol level. Partial correlation analysis of the data showed that plasma insulin and cortisol were both significant influences on hepatic glucose-6-phosphatase activity in utero, but plasma cortisol had the more pronounced effect. Cortisol, therefore, appears to be a physiological regulator of tissue glucose-6-phosphatase activity in utero and enhances the glucogenic capacity of the sheep fetus during late gestation.

Hypothalamo-pituitary disconnection in the fetal sheep

In this study we have applied the technique of hypothalamo-pituitary disconnection (HPD) to the fetal sheep at 108-112 days of gestation. The pituitary is surgically disconnected from the hypothalamus by the removal of the neural component of the median eminence above the level of the portal circulation. This procedure results in the complete disconnection of the pituitary from the hypothalamus. After HPD, the lactotroph response to the dopamine antagonist chlorpromazine was significantly reduced (p less than 0.005) indicating the functional isolation of the pituitary gland from the hypothalamus. The increase in plasma prolactin in response to exogenous thyrotrophin-releasing factor was maintained following HPD. HPD resulted in the complete atrophy of the pars nervosa. At 132-135 days of gestation after HPD there was no change in the volume or appearance of the pars distalis; small infarcts were observed in the pars distalis of some HPD fetuses, but these occupied less than 1% of the volume of the anterior lobe of the pituitary. There was a significant increase (p less than 0.05) in the volume of the pars intermedia after HPD. Gestation was prolonged for at least 8 days beyond normal term following HPD, indicating that the processes integral to the initiation of parturition at term had been disrupted. We conclude that HPD provides a good in vivo model for the investigation of the activity of the isolated pituitary gland, and for the examination of the role of neuroendocrine mechanisms in fetal sheep development in the latter third of gestation.

Tricuspid and pulmonary atresia with coarctation of the aorta: a rare combination possibly explained by persistence of the fifth aortic arch with a systemic-to-pulmonary arterial connection

A ten-day old baby was found to have tricuspid and pulmonary atresia, and a "ductal-dependent" pulmonary circulation that was prostaglandin-sensitive. An unusual coarctation of the aorta was not recognised until an autopsy was performed, some 11 days after construction of an aortopulmonary shunt. A previously undefined anomaly in this neonate was persistence of the fifth aortic arch with a systemic-to-pulmonary artery connection on the same side as the definitive aorta. The histology of the fifth aortic arch is consistent with the pattern of an arterial duct.

Cardiac and neurological abnormalities in v-fps transgenic mice

Transgenic mice that widely express the v-fps protein-tyrosine kinase develop several independent pathological conditions, in addition to a high tumor incidence. v-fps expression and protein-tyrosine kinase activity in the heart were directly correlated with cardiac enlargement. This cardiomegaly was accompanied by severe myocardial and endocardial damage, which was concentrated in the left ventricular wall, and characterized by a progressive atrophy and necrosis of cardiac muscle fibers with concomitant fibrosis. This pathology was associated with congestive heart failure. Mice from five lines developed a marked trembling, correlated with expression of the v-fps transgene in the brain, and two lines showed a striking bilateral enlargement of the trigeminal nerves. Unlike tumor formation, these cardiac and neurological phenotypes were evident shortly after birth and showed 100% penetrance. The pleiotropic effects of the v-fps transgene suggest the involvement of protein-tyrosine kinases in mammalian neural development and cardiac function.