Bioavailability of dietary urea nitrogen in the infant

Because the human body has no enzymes capable of hydrolyzing urea, nitrogen from this source becomes bioavailable only by release of ammonia from urea by bacterial hydrolysis in the intestines, with subsequent absorption and utilization of ammonia. To explore extent to which urea ingested in milk becomes bioavailable, we fed di-15N-urea (both nitrogen atoms in the form of the stable isotope 15N) and determined urinary excretion of di-15N-urea (excreted without having become bioavailable) and mono-15N-urea (urea containing only one atom of 15N and therefore reflecting excretion of absorbed ammonia). The largest percentage of the ingested di-15N-urea was excreted promptly in the urine still in the form of di-15N-urea. We conclude that most of the urea ingested by a normal infant is not bioavailable.     

The reliability and clinical use of a rapid phosphatidylglycerol assay in normal and diabetic pregnancies

Lecithin phosphorus concentration, the standard fetal lung maturity test in our institution, and phosphatidylglyercol were assayed in 69, 29, and 45 amniotic fluid samples from normal (GI), gestational (GII), and insulin-dependent diabetic (GIII) women by means of thin layer chromatography and Amniostat-FLM, respectively. Lecithin phosphorus concentration greater than or equal to 0.1 mg/dl and positive or strong positive Amniostat-FLM results were considered mature. The results of both assays were concordant in 79% of the samples. The discordance rate was highest in GIII patients. In our experience, respiratory distress syndrome did not develop in neonate infants of diabetic women delivered after a mature lecithin result. With lecithin phosphorus concentration as the reference standard, the predictive value of a mature Amniostat-FLM result was 96.2%, whereas that of an immature result was 58.5%. Respiratory distress syndrome occurred in only two GIII neonates who were delivered within 72 hours of both immature lecithin and Amniostat-FLM results. These findings support the use of Aminostat-FLM as a screening test for fetal lung maturity in both normal and diabetic pregnancies. Additional tests will be necessary to evaluate further fetal lung maturity only if the results are negative.     

Fetal deaths in Alabama, 1974-1983: a birth weight-specific analysis

Birth weight-specific fetal death rates were evaluated for Alabama for the years 1974-1983. The fetal death rate for the total low birth weight group improved less than 20% during the decade, whereas the fetal death rate for the 2500-3999-g birth weight group improved 40%, and the fetal death rate for the group of 4000 g or more improved 71%. By 1983, 76% of all stillbirths weighed less than 2500 g, compared with 66% in 1974. In contrast, in both years, only about 7% of live births weighed less than 2500 g. This study suggests that increased reporting of stillbirths of less than 500 g has contributed to the recent apparent lack of improvement in stillbirth rates in Alabama.     

Thyroid gland size in pregnancy. An ultrasound and clinical study

We estimated the size of the thyroid gland by palpation and measured thyroid gland volume with ultrasound in the immediate postpartum period and six months after delivery in 16 women. The 13% reduction in the mean thyroid gland volume detected six months after delivery implied that the thyroid gland enlarges slightly during pregnancy. Physical examination, however, did not detect any goiters during the immediate postpartum period and did not identify a change in thyroid gland size six months after delivery. The thyroid gland enlargement that occurs during pregnancy is not large enough to be detected by physical examination. We urge physicians to discard the commonly held notion that goiter frequently develops during pregnancy.     

Apgar scores and umbilical arterial pH in preterm newborn infants

One- and five-minute Apgar scores and umbilical cord arterial pH values were compared in preterm newborn infants of various gestational ages. The more premature the infant, the more likely the Apgar score was low in the presence of a pH greater than or equal to 7.25. Conversely, the closer to term, the more frequently an infant with a pH of less than 7.25 had an Apgar score of greater than or equal to 7. Therefore, in preterm infants, there is little congruity between the Apgar score and umbilical cord pH. Based on these findings, it is not appropriate to label preterm newborn infants as asphyxiated based on a low Apgar score.     

Intestinal permeability in the newborn

Passive intestinal permeability in 33 newborn babies was studied using feeds containing lactulose and mannitol. Each marker is thought to pass across the gut wall by a different route; lactulose by a paracellular and mannitol by a transcellular pathway. Neither is metabolised and both are wholly and solely excreted by the kidney; urinary recovery is a measure of the intestinal uptake. Babies born before 34 weeks' gestation exhibited a higher intestinal permeability to lactulose than more mature babies, and all preterm babies showed an appreciable decline in lactulose absorption during the first week of oral feeds. Babies of 34 to 37 weeks' gestation achieved a 'mature' intestinal permeability to lactulose within four days of starting oral feeds. These findings may reflect the immaturity of the gut of the preterm baby rather than a process essential to adaptation to enteral nutrition.     

Prognostic significance of hypernatremia and hyponatremia among patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE: Abnormal serum sodium levels (hyponatremia and hypernatremia) are frequently observed during the acute period after aneurysmal subarachnoid hemorrhage (SAH) and may worsen cerebral edema and mass effect. We performed this study to determine the prognostic significance of serum sodium concentration abnormalities. METHODS: We analyzed prospectively collected data for the placebo treatment group in a clinical trial conducted at 54 neurosurgical centers in North America. The presence of hypernatremia (serum sodium concentration of >145 mmol/L) and hyponatremia (serum sodium concentration of <135 mmol/L) was determined with serum sodium measurements obtained at admission and 3, 6, and 9 days after SAH. The effects of hypernatremia and hyponatremia on the risk of symptomatic vasospasm and on 3-month outcomes were analyzed after adjustment for the following potential confounding factors: age, sex, preexisting hypertension, admission Glasgow Coma Scale score, initial mean arterial pressure, subarachnoid clot thickness, intraventricular blood or intraparenchymal hematoma, ventricular dilation, and aneurysm size and location. RESULTS: Of 298 patients in the analysis, 58 (19%) developed hypernatremia and 88 (30%) developed hyponatremia. Hypernatremia was significantly associated with poor outcomes (odds ratio, 2.7; 95% confidence interval, 1.2-6.1). A positive correlation was observed between the highest sodium values recorded and Glasgow Outcome Scale scores at 3 months (P < 0.0001 by analysis of variance). Hyponatremia was not associated with 3-month outcomes (odds ratio, 1.9; 95% confidence interval, 0.9-4.3). Neither hypernatremia nor hyponatremia was associated with the risk of symptomatic vasospasm. CONCLUSION: Hyponatremia seems to be more common than hypernatremia after SAH. However, hypernatremia after SAH is independently associated with poor outcomes, and this association is independent of previously identified outcome predictors, including age and admission Glasgow Coma Scale scores. Further studies are needed to define the underlying mechanism of this association.     

Interactive use of cerebral angiography and magnetoencephalography in arteriovenous malformations: technical note

OBJECTIVE: To minimize the risks associated with treating cortical cerebral arteriovenous malformations (AVMs), we developed a technique combining functional imaging and cerebral angiography. The functional loci obtained by performing magnetoencephalography (MEG) are projected onto stereoscopic pairs of a stereotactically derived digital subtraction angiogram. The result is a simultaneous three-dimensional perspective of the angioarchitecture of an AVM and its relationship to the sensorimotor cortex. METHODS: Eight patients underwent multimodality brain imaging, including magnetic resonance imaging, functional mapping via MEG, and stereotactic angiography using a modified Compass fiducial system (Compass International, Rochester, MN). The coordinates derived by performing MEG were superimposed onto stereotactic, stereoscopic, angiographic pairs using custom-made distortion correction and coordinate transfer software. RESULTS: The magnetoencephalographic angiogram allowed simultaneous viewing of the angioarchitecture of the AVM nidus, the feeding vessels, and the draining veins and their relationship to the normal cerebral vasculature and functional cortex. This imaging technique was particularly valuable in identifying en passant vessels that supplied functional cortex and was used during the treatment of these lesions. CONCLUSION: The techniques of MEG and cerebral angiography were combined to provide simultaneous viewing of both modalities in a three-dimensional perspective. This technique can aid in risk stratification in the management of patients with cerebral AVMs. In addition, this technique can facilitate the selective targeting of vessels, thus potentially reducing the risks associated with embolization of these formidable lesions.     

Acromegaly caused by a growth hormone-releasing hormone-secreting carcinoid tumor: case report

OBJECTIVE AND IMPORTANCE: We describe a patient with acromegaly and pituitary hyperplasia secondary to a growth hormone-releasing hormone-secreting gastrointestinal carcinoid tumor. This case report illustrates the importance of including this rare clinical syndrome in the differential diagnosis of acromegaly for patients with suspected or known neuroendocrine tumors. CLINICAL PRESENTATION: A 19-year-old, Asian-American, male patient with a 2-year history of a nonresectable, metastatic, intestinal carcinoid tumor presented with complaints of headaches, arthralgias, sweats, and changing features. The examination revealed a young subject with acromegalic features, without visual field deficits. Magnetic resonance imaging revealed a diffuse sellar mass that extended suprasellarly to compress the optic chiasm. Endocrinological studies demonstrated a growth hormone level of more than 100 ng/ml and an inappropriately elevated growth hormone-releasing hormone level. INTERVENTION: The patient underwent transsphenoidal resection of the pituitary mass for diagnostic and decompressive purposes. The pathological examination revealed pituitary hyperplasia, without evidence of an adenoma. Therapy with long-acting repeatable octreotide (Sandostatin LAR; Novartis AG, Basel, Switzerland) was initiated postoperatively, to further control the acromegaly and carcinoid tumor. The soft-tissue swelling resolved, and the patient remained free of headaches, arthralgias, and sweats at the 6-month follow-up examination. CONCLUSION: Ectopic acromegaly is a rare syndrome that must be recognized by neurosurgeons because its treatment differs from that of classic pituitary acromegaly. We describe a patient for whom this syndrome was documented with magnetic resonance imaging, endocrinological testing, and pathological examinations.