Metabolic adaptations for desert survival in the Bedouin goat.

Energy conservation is a key adaptation for desert survival in the Bedouin goat. When food is scarce, metabolism is reduced and body weight can be maintained indefinitely on less than one-half of normal intake. We hypothesized that metabolism would be turned down during both rest and exercise, but it was not. It was low when animals rested and returned to normal during exercise. We expected catecholamines and thyroid hormones would modulate metabolism, but they did not. The reduction in metabolism preceded any change in thyroid hormone concentrations, and infusions of epinephrine did not restore reduced metabolism to normal levels. Finally, we expected the gut would be the major organ system involved in the metabolic reduction because less food is eaten, processed, and absorbed. Contrary to our expectations, we found that muscle is the primary organ system responsible for the reduction. It appears that the adaptations of the Bedouin goat for surviving on limited food supplies involve different organ systems and different modulators to reduce metabolism from those known for other mammals.

Modulation of plasma arginine vasopressin during rehydration in the Bedouin goat.

When severely dehydrated Bedouin goats were allowed to drink to satiation their plasma arginine vasopressin concentration immediately dropped from a value of 19.9 +/- 9.4 pmol.l-1 to 9.4 +/- 3.9 pmol.l-1 (P < 0.05). It continued to drop further until a concentration of 1.8 +/- 2.9 pmol.l-1 was recorded, similar to that reported for goats allowed to drink freely. When the goats were shown the water but drinking was denied, plasma arginine vasopressin immediately dropped to 11.7 +/- 4.0 pmol.l-1 (P < 0.05) and further decreased to 10.0 +/- 4.8 pmol.l-1 5 min following their sighting the water. This level, however, was not sustained and 2 h after the initial drop the high pre-trial concentration of plasma arginine vasopressin was regained. Presumably, sighting of water by dehydrated goats induces an abrupt drop in their plasma arginine vasopressin level even before drinking commences. When rehydrated, by introducing water directly to the rumen, circumventing both the sensing of the water and the drinking proper, no immediate drop in the plasma arginine vasopressin concentration of the newly rehydrated goats was observed. A delayed drop in the plasma arginine vasopressin levels took place slowly, concurrently with the drop in osmolality and concentration of Na+ in the plasma. It is suggested that sighting of water by dehydrated goats is involved in the modulation of plasma arginine vasopressin.

Dehydration and rehydration in donkeys: the role of the hind gut as a water reservoir.

Body fluid distribution was measured in three donkeys, fully hydrated, following dehydration and after being rapidly rehydrated. In twenty other donkeys that were slaughtered to supply food for predators in a safari zoo, the water content in the different compartments of the gastrointestinal tract (GIT) was assessed. Prior to being slaughtered, four of the animals were fully hydrated, four dehydrated and 12 dehydrated, rehydrated and then slaughtered and examined, four at 1, for at 3 and four at 5 hours following drinking. When the body mass of dehydrated donkeys dropped to 75.4 +/- 2.4% of their initial value, total body water of the animals (HTO space), extracellular volume (SCN space) and plasma volume (EB space) were reduced to 76.6 +/- 5.3%, 80.9 +/- 10.6% and 73.2 +/- 8.3% of their initial values, respectively. The amount of water retained in the GIT of the fully hydrated donkeys amounted to 15.9 +/- 3.4 1, 19% of total body water. In the dehydrated donkeys it was only 7.4 +/- 1.3 1. The calculated total intracellular volume in the dehydrated donkeys was only 14% lower than in the fully hydrated animals. When drinking was allowed, dehydrated donkeys consumed 17.6 +/- 2.4 1 of water. The increase in the water content in the gut of newly rehydrated donkeys matched this volume, 80% of which was retained in the hind gut. During the five hours after drinking, only slow and moderate changes in the volume of the hind gut were recorded. Changes in plasma volume were also suppressed. It is suggested that the hind gut of the donkey, similar to the rumen of goats and sheep, plays a role as a water reservoir that helps maintain the osmotic stability of the body.

Clinical application of ultrasonography in the diagnosis of intussusception.

Sixty-five consecutive patients seen in a pediatric emergency department, in whom the diagnosis of intussusception was considered, had an ultrasound examination of the abdomen before a barium enema. The mean age of the patients was 1.7 years (range 2 weeks to 5 years). Intussusception was detected by ultrasonography in all 20 cases proved by barium enema. There were three false-positive ultrasound results (sensitivity = 100%, confidence interval (Cl) = 86% to 100%; specificity = 93%, Cl = 86% to 96%). Normal findings on ultrasonography correlated with a negative barium enema results in 42 of 42 cases (negative predictive value = 100%, Cl = 94% to 100%). No intussusception was missed by ultrasonography. To determine which patients would most benefit from ultrasonography, we divided patients into either a high-risk group (81% with intussusception) or a low-risk group (14% with intussusception) on the basis of clinical symptoms (p less than 0.01). If each high-risk child had a barium enema and each low-risk child had an ultrasound study as their initial diagnostic test, 89% of the patients in this study would have undergone only one examination. We conclude that ultrasonography can be used as a rapid, sensitive screening procedure in the diagnosis or exclusion of childhood intussusception. Children considered at low risk of having intussusception on the basis of clinical symptoms should initially have an ultrasound examination; patients at high risk should have an immediate barium enema.

Ultrasound screening of high-risk infants. A method to increase early detection of congenital dysplasia of the hip.

Congenital dysplasia of the hip (CDH) continues to be missed by routine physical screening examinations in the early months when treatment is most effective. Real-time ultrasonography (US) is valuable in the detection of CDH in the young infant. We performed a prospective study to evaluate one US screening strategy that targets a select "high-risk newborn" population at risk for CDH aiming to increase the early diagnosis of this condition. From 1772 consecutive births at one hospital, we identified 97 (5.5%) newborns with risk factors for CDH: breech delivery, 73 babies; family history, 26 babies; postural abnormalities, five babies; and oligohydramnios, four babies. Eleven newborns had two risk factors. We studied 69 of these newborns with US. There were four cases of CDH in this group. Three of these babies had completely normal pediatric physical examination results at the time of the US study (at 14, 75, and 100 days, respectively) despite dysplasia diagnosed by US. All were successfully treated with a harness as outpatients. We conclude that a screening program entailing identification and subsequent US of the hip of newborns with specific physical and historical risk factors for CDH increases early diagnosis. Further analysis suggests this approach is cost-effective.

Favorable outcome of neonatal aortic thrombosis and renovascular hypertension.

Fifteen children with renovascular hypertension as a result of aortic thrombosis were followed for a mean of 26 months (range 5 to 58 months) to determine outcome. As neonates, all patients had hypertension and elevated plasma renin activity. Of 11 patients studied with radionuclide renography and scintigraphy, 10 had abnormal renal blood flow; three had complete absence of unilateral perfusion. On follow-up examination all children were normotensive; five children ages 5 to 24 months required antihypertensive medication. Of 15 children, 14 had normal statural growth; all had normal serum creatinine, plasma renin activity, and calculated glomerular filtration rate values. Patients with complete absence of renal perfusion unilaterally remained functionally anephric; children with less severe perfusion deficits had improved perfusion as shown by radionuclide renography and scintigraphy. We believe that many patients with aortic thrombosis and renovascular hypertension who have had aggressive antihypertensive therapy in the neonatal period will have good renal function and increased perfusion to the affected kidney 2 years later.

Ultrasound of the distal pouch in infants with imperforate anus.

Optimal surgical management of the newborn with imperforate anus depends on accurate determination of the level of the rectal pouch. Eighteen children with imperforate anus were evaluated with ultrasound. The distance from the end of the pouch to the perineum was measured. Ultrasound correctly predicted the level of the distal pouch in all 12 children who had confirmation of the pouch level by surgery or by distal contrast stomagrams. Six children have not yet had definitive surgery. Five children with a pouch to perineum (P-P) distance of less than or equal to 10 mm and three of six children with a P-P distance of 10 to 15 mm had successful correction by a simple perineal anoplasty. Three of six children with a P-P distance of 10 to 15 mm and all of those (seven) with a P-P distance greater than 15 mm were diverted with colostomies.

Pulmonary sequestration. Diagnosis by ultrasound.

Sonographic imaging of a basilar chest mass in each of three newborns and in a 2-month-old infant either confirmed or correctly suggested the diagnosis of surgically documented pulmonary sequestration. The appearance of each mass was that of a highly echogenic lesion, the homogeneity of which was interrupted only by vascular structures. In two cases, an artery was identified arising from the aorta and extending into the mass, thus confirming the diagnosis. Chest sonography should be utilized when the possibility of a pulmonary sequestration is considered.

Factors determining the digestive efficiency of the domesticated donkey (Equus asinus asinus).

Factors determining the digestive efficiency of donkeys were studied in animals fed either a low quality roughage (wheat straw: 77.1% neutral detergent fibre, 2.8% crude protein) or a high quality forage (alfalfa hay: 47.5% neutral detergent fibre, 22.7% crude protein). The neutral detergent fibre (NDF) intake when fed wheat straw was 1693 +/- 268 g animal-1 day-1, 10% higher than when fed alfalfa hay. Digestive coefficient of NDF and acid detergent fibre (ADF) when fed wheat straw amounted to 50.9 +/- 4.9 and 42.0 +/- 4.1% respectively. NDF and ADF apparent digestibilities and mean retention times (37.7 +/- 1.7 and 36.4 +/- 3.2 h respectively) were not significantly different (P greater than 0.05) between the two diets. The donkey appears to digest cell wall constituents as efficiently as the Bedouin goat when on low quality roughage, but less efficiently when fed alfalfa hay. Its energy digestibility is, however, as high as that reported for the Bedouin goat. The donkey's high energy digestibility is related to its capacity to digest soluble food components more efficiently than the ruminant. The mean retention time in the donkey is shorter than in the Bedouin goat and is consistent with its capacity to compensate for a lower quality diet by increasing its intake rate. Recycling of urea in donkeys maintained on wheat straw amounted to 75.5 +/- 13.0% of the entry rate. A decrease in the rate of renal urea filtration, coupled with an increase in the fraction reabsorbed, increased the retention of nitrogenous waste and permitted recycling of nitrogen into the gut.

Radiographic evaluation of subureteric injection of teflon to correct vesicoureteral reflux.

The imaging studies of 83 children (115 ureters) with vesicoureteral reflux who were treated by subureteric injection of Teflon (STING) were reviewed. On plain films, the Teflon rarely may be seen as faintly radiodense. On sonography, it is echogenic and has variable acoustic shadowing. On CT it is dense (160-466 H). Postsurgical cystography showed cessation of reflux in 83 ureters (72%). Complications of STING were uncommon. No granulomatous masses were identified in the region adjacent to the STING. Transient, free peritoneal fluid developed in three children and ureteral dilatation in six, three of whom required intervention. In one child, most of the Teflon disappeared from the original site of injection, as noted on a follow-up CT scan; possibly it had been extruded into the bladder. The STING procedure probably will become more popular. Knowledge of its radiologic appearance is important for the radiologist in order to effectively evaluate these children postoperatively.

Ultrasonography and diagnosis of pediatric genitourinary rhabdomyosarcoma.

Rhabdomyosarcoma is the most common tumor of the lower genitourinary tract in children during their first two decades of life. Four patients with genitourinary rhabdomyosarcoma are presented, with ultrasonographic and radiographic findings. The utility of ultrasound in the diagnosis of this pediatric tumor is emphasized.

Radiological approaches in the evaluation of joint disease in children.

In summary, the newer technologies in radiology have allowed us to visualize more clearly the manifestation of joint disease in children. The presence of small erosions and cartilage damage can be seen much better with magnetic resonance imaging than with any other modality short of arthrography, a much more invasive examination. Joint effusion, although sometimes visualized with conventional radiography, is probably best recognized with ultrasound or magnetic resonance imaging, although it can be detected with computed tomography as well. For the evaluation of avascular necrosis that can be associated with steroid use in joint disease, bone scintigraphy is a simple, sensitive method. Magnetic resonance may be as or more sensitive and gives additional information as well. In the detection of change with time, conventional radiography probably will remain the standard as it is still the simplest, least expensive examination; however, it has many limitations in specific cases. Bone scintigraphy may be of value in selected cases. Although we have still not had enough experience with magnetic resonance imaging to use it as a way of evaluating progress of joint disease, it promises to be the most sensitive radiologic measure of evaluating progress as small anatomical changes can be detected within the cartilage, which cannot be done easily with other means.

MR imaging of osteoid osteoma.

An osteoid osteoma was detected in a young boy with a classic history for this lesion. Plain radiography was not helpful but ultrasound and magnetic resonance imaging demonstrated the tumor nidus.

Neonatal aortic thrombosis: recent experience.

To evaluate the course, use of diagnostic modalities, management, and outcome of aortic thrombosis associated with umbilical artery catheterization, we reviewed 20 cases of aortic thrombosis diagnosed by ultrasonography (n = 16) or aortography (n = 4) over 4 years. Fourteen of 20 infants had severe perinatal asphyxia, suggesting that asphyxia predisposes to aortic thrombosis. Ultrasonography provided information about the size, location, and configuration of the thrombus and was useful in following thrombus size with therapy. Radionuclide renography-scintigraphy demonstrated abnormal renal function in all 11 patients scanned. Six patients with minor thrombosis (hypertension as the only sign) improved without specific therapy. Nine infants had moderate thrombosis (multiple signs but normal urine output); all survived with a variety of therapies; two were not given anticoagulant or fibrinolytic agents; three improved with heparin alone; and one had surgery without recurrence of the thrombus. Resolution of moderate thrombosis followed streptokinase therapy in two of three infants. All five babies with anuria from major thrombosis died. Hepatic infarction associated with aortic thrombosis was found in three of three autopsies.

Effect of dehydration and rapid rehydration on renal function and on plasma renin and aldosterone levels in the black Bedouin goat.

Bedouin goats in the extreme deserts of the Middle East are regularly subjected to severe dehydration and possess a capacity to rapidly rehydrate by drinking large volumes of water. Urine flow, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in the fully hydrated animals amounted to 0.74 +/- 0.4 ml X min-1, 76 +/- 29 ml X min-1 and 344 +/- 146 ml X min-1 respectively. In goats that were dehydrated to a loss of about 30% of their initial body weight, urine flow dropped to 24% of the value recorded in the hydrated animals and GFR and ERPF dropped to half their level recorded in the hydrated phase. Na and K+ excretion decreased in the water depleted goats and further decrease was recorded following drinking. Following drinking the urine flow, GFR and ERPF of the recently rehydrated goats dropped to below the rates recorded in the dehydrated animals. During the 3 h of the continuous recording that followed the drinking, all three rates did not exceed the predrinking level. Plasma renin activity amounted to 0.37 +/- 0.32 ng AI X ml-1 X h-1 in the hydrated animals. In dehydrated ones it amounted to 4.8 +/- 2.8 ng AI X ml-1 X h-1 and a further increase was recorded following drinking. Aldosterone in the hydrated goats was 5.5 +/- 4.3 ng% and increased to 13.9 +/- 2.3 ng% in the dehydrated animal and amounted to 20.1 +/- 5.5 ng% 2 h following drinking.(ABSTRACT TRUNCATED AT 250 WORDS)