Diagnostic accuracy of 3-T magnetic resonance imaging with 3D T1 VIBE versus computer tomography in pars stress fracture of the lumbar spine.

OBJECTIVE: To compare the diagnostic accuracy of 3-T magnetic resonance imaging (MRI) with thin-slice 3D T1 VIBE sequence to 128-slice computer tomography (CT) in pars stress fractures of the lumbar spine. MATERIALS AND METHODS: 3-T MRI and CT of 24 patients involving 70 pars interarticularis were retrospectively reviewed by four blinded radiologists. The fracture morphology (complete, incomplete, or normal) was assessed on MRI and CT at different time points. Pars interarticularis bone marrow edema (present or absent) was also evaluated on MRI. RESULTS: In total, 14 complete fractures, 31 incomplete fractures and 25 normal pars were detected by CT. Bone marrow edema was seen in seven of the complete and 25 of the incomplete fractures. The overall sensitivity, specificity and accuracy of MRI in detecting fractures (complete and incomplete) were 97.7, 92.3, and 95.7 %, respectively. MRI was 100 % accurate in detecting complete fractures. For incomplete fractures, the sensitivity, specificity, and accuracy of MRI were 96.7, 92.0, and 94.6 %, respectively. CONCLUSIONS: 3-T MRI with thin-slice 3D T1 VIBE is 100 % accurate in diagnosing complete pars fractures and has excellent diagnostic ability in the detection and characterization of incomplete pars stress fractures compared to CT. MRI has the added advantages of detecting bone marrow edema and does not employ ionizing radiation.

Conviviality in Catalonia.

Food, essential to social interaction everywhere, has particular importance in the regeneration of this rural community in Catalonia. The misery of the Civil War in Spain was followed by three decades of rural depopulation and economic decline, but a gradual return to the countryside since the 1980s has encouraged the revival of villages like Mieres. Food and drink play a fundamental role in the fiestas, fairs, and other celebrations that pack the public calendar, creating and sustaining social interaction and rebuilding a sense of community.

Comparison of the bilirubin concentration and the bilirubin/albumin ration with the bilirubin-binding ability in neonatal serum.

The bilirubin-binding ability of neonatal serum was measured and compared with the serum bilirubin concentration and the serum bilirubin/albumin ratio. The bilirubin/albumin ratio correlated no better with the bilirubin-binding ability than the bilirubin concentration alone.

Effects of glucose or insulin infusions on growth hormone secretion in male red deer.

The growth hormone (GH) secretory pattern in male red deer is associated with the seasonal growth cycle. During this cycle metabolic state changes from weight gain in spring to weight loss in winter. However, short-term metabolic changes due to feeding could also alter the GH pattern. To investigate the effect of such changes on GH secretion, the acute feedback of blood glucose level on the GH secretory pattern was examined. Six yearling male red deer were infused iv with glucose (G; 150 mg/kg/hr) or insulin (I; 30 mU/kg/hr) for a 12-hr period, 1 week apart. GH was measured in jugular venous blood every 10 min, for 12 hr before, during, and 6 hr after the infusions. Glucose, insulin, IGF-1, and haematocrit were also measured. There was no difference (P > 0.05) in glucose levels between G and I prior to infusions (5.8 vs 6.0 mmol/liter, SED = 0.42). Glucose levels rose to 8.7 mmol/liter during G and fell to 3.4 mmol/liter (SED = 0.72, P <0.001) during I, then returned towards normal postinfusion. Insulin levels increased during G and I (P < 0.01) with no difference (P > 0.05) between G and I during preinfusion (163 +/- 7.6 pmol/liter) or infusion (259 vs 264 +/- 16. 5 pmol/liter) periods. There were no differences (P > 0.05) in GH secretory characteristics, mean IGF-1, or haematocrit between G and I. However, there were significant effects of infusion within the treatments. Mean GH declined (P < 0.05) from 1.8 ng/ml (both treatments) preinfusion to 1.13 and 1.31 ng/ml during G and I infusion, respectively. GH pulse amplitude was lower during I infusion (5.6 ng/ml vs 8.2 ng/ml preinfusion, P < 0.05, SED = 1.0) and the change in amplitude from preinfusion to infusion differed (P > 0.05) with an increase in G and a decrease in I (+0.6 and -2.6, SED = 1.1). IGF-1 levels were stable and averaged 555 and 520 ng/ml (SED = 34.9) for G and I, respectively. Haematocrit declined from 34.3 +/- 1.85% over the first 4 hr of sampling to 25.7 +/- 0.97% for the remainder of the sampling period. The finding that there were no major alterations in GH secretory patterns during 12 hr of hypoglycemia and hyperglycemia suggests that GH secretion in the male red deer is relatively insensitive to short-term changes in metabolic state.

Feeding premature infants.

We have tried to offer a rational approach to the methods of premature infant feeding. Most of our information is incomplete, and many of the presumptions used in deciding feeding technique are not based on reliable scientific data. The calculations presented in this discussion are valuable as teaching methods in the nursery. The complexity of the questions about premature infant feeding makes it necessary for personnel in the neonatal unit to focus regularly on infant feeding and to allow for time dedicated to considering their suggestions.

The effect of chloral hydrate and its metabolites, trichloroethanol and trichloroacetic acid, on bilirubin-albumin binding.

Chloral hydrate is used as a sedative in infants requiring ventilatory support. The metabolites, trichloroethanol and trichloroacetic acid, accumulate in the serum and are protein bound. The possibility that these chemicals might compete with bilirubin for albumin binding was tested using the peroxidase method and a dialysis rate method. Chloral hydrate and trichloroethanol had no effect on bilirubin-albumin binding. Trichloroacetic acid affects bilirubin-albumin binding but to a degree that would be dangerous only in infants with an unusual accumulation of this metabolite.

Evaluation of a spectrophotometric method for measurement of activity of diamine oxidase in newborn infants.

Diamine oxidase (DAO) is an enzyme synthesized primarily in the gastrointestinal mucosal cells. Serum levels of DAO have been used as an indicator of the integrity and/or functional mass of the intestinal mucosa. The enzyme is also produced by the placenta and is elevated in newborn serum. Previous radiometric methods for DAO used tritiated putrescine or cadaverine as substrate. A simple and rapid spectrophotometric procedure for DAO with use of histamine as substrate was developed, and this assay was utilized to evaluate the developmental pattern of activity of DAO in umbilical cord blood of newborn full-term and premature infants, in sequential samples from premature infants, and in samples from infants with necrotizing enterocolitis. The spectrophotometric assay was linear to 200 U per L and was also precise with total imprecision (CV) of 11.9 percent and 3.7 percent at DAO activities of 25.6 U per 1 and 126.1 U per L, respectively. Triglycerides above 275 mg per dL caused a significant reduction in measured activity of DAO; however, this effect could be eliminated by use of ultracentrifugation to remove lipemia. Plasma samples with heparin or ethylenediamine tetraacetic acid (EDTA) as anticoagulant were unsuitable for analysis since DAO activity showed a 24 percent and 32 percent decrease in activity at concentrations of 20 U per mL (heparin) and two mg per mL (EDTA), respectively. Serum samples are the specimen of choice. In infants it was found that the serum activity declined to adult levels by day 12 of life and that this decline is not affected by necrotizing arterocolitis.

Cefmenoxime and bilirubin: competition for albumin binding.

Certain drugs are known to compete with bilirubin for albumin binding; therefore, all drugs administered to neonates should be tested to determine the degree of competition. The effect of cefmenoxime on bilirubin-albumin binding was determined by comparing the oxidation rate of free bilirubin in the presence and absence of drug. The reserve albumin concentration (RAC) of pooled cord serum was also measured using the MADDS dialysis rate method. We show that cefmenoxime competes with bilirubin for albumin binding with a displacement constant, of 3.1 x 10(3) l/mol. The maximal displacement factor (MDF) is used to determine the clinical effect of the drug at usual serum concentrations. The MDF for cefmenoxime is 1.10, representing approximately a 10% increase in free bilirubin concentration. In comparison, the MDF for a known bilirubin displacing drug, sulfisoxazole, is 2.43. The MADDS method showed an estimated 28% decrease in the RAC at 150 mumol/l, the mean peak serum concentration (MPSC) of cefmenoxime. These results show while cefmenoxime affects bilirubin-albumin binding, the degree of the effect is relatively small. However, cefmenoxime may pose a hazard to very sick, premature infants, especially if the infant is jaundiced.

Pharmacokinetics of gentamicin in neonates on extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) has been used in more than 1,000 infants in 50 centers in the United States. The extracorporeal circuit contains approximately 400 ml of blood, an amount exceeding the blood volume of most full-term neonates. The effect of this additional blood volume on drug disposition is unknown. In this study, we determined the pharmacokinetic parameters of gentamicin in 10 infants on ECMO. Gentamicin concentrations were determined by a fluorescence polarization immunoassay. Pharmacokinetic parameters were determined from these concentrations by using a two-compartment model. Our study demonstrated a mean steady-state volume of distribution of 0.51 +/- 0.11 liters/kg, a figure similar to that in previous studies of full-term infants. The elimination half-life was found to be prolonged (mean, 573 +/- 263 min). The creatinine level in the plasma of the infants was found to be a statistically significant predictor of elimination half-life. Recommendations regarding initial dosing levels of gentamicin in infants on ECMO are made.

The effect of hydrocortisone, thyroxine, and phenobarbital on diamine oxidase activity in newborn rat intestine.

There is a reported association between administration of prenatal glucocorticoids and a decreased incidence of necrotizing enterocolitis in human infants. In rats, the degree of ischemic bowel disease correlates negatively with intestinal diamine oxidase (E.C. 1.4.3.6) activity. Since the administration of hydrocortisone, thyroxine, or phenobarbital to newborn rat pups affects the development of intestinal enzymes, we were interested in knowing whether hydrocortisone, thyroxine, or phenobarbital specifically affect intestinal diamine oxidase activity. We injected rat pups with hydrocortisone sodium succinate, 1-thyroxine pentahydrate, sodium salt, sodium phenobarbital, or the control solution on days 4, 6, 8, or 10 of life (phenobarbital, days 3, 5, 7, or 9). Pups were injected 3 days consecutively (phenobarbital, 4 days), and all were sacrificed on days 7, 9, 11, and 13. Intestinal diamine oxidase and intestinal invertase (E.C. 3.2.1.26) activities were measured. Invertase was used as a control enzyme because it is known to be induced by glucocorticoid hormones. We found that the hydrocortisone-injected pups had 10-fold higher specific activity of invertase than the saline-injected animals. Diamine oxidase activity was significantly higher in the group receiving hydrocortisone and sacrificed on days 7, 9, and 11. Enzyme activity in both the hydrocortisone-injected and saline-injected groups was equal on day 13, as was enzyme activity on all days in the thyroxine-injected and sodium hydroxide-injected groups, and the phenobarbital-injected and the saline-injected groups. Our results suggest that diamine oxidase activity may be induced by hydrocortisone, but is not affected by thyroxine or phenobarbital.

Quality control of laboratory tests run in a neonatal intensive care unit.

We examined the accuracy of laboratory screening tests in eight neonatal intensive care units. Analytes were provided by the EXCEL proficiency testing program of the College of American Pathologists (CAP), Skokie, III, samples were analyzed for hematocrit values and urine specific gravity. "Dipstick" tests were also performed for urinary protein, bilirubin, blood, glucose, pH, and ketones. The one intensive care unit that adhered to a formal quality control program for all these tests uniformly reported results well within statistically acceptable limits as defined by CAP. The seven other centers reported 14 instances of results that were either greater than 1 SD of the mean or considered by the consensus method to be outside acceptable CAP limits. Three of these results may have led to inappropriate clinical action in neonates. We conclude that there is a real potential for errors to be made in screening tests run by nurses in a neonatal intensive care unit when a formalized quality control program is not in effect.

Vitamin E in neonatology.

It is difficult to maintain an objective attitude toward the use of vitamin E in neonatology. On the one hand, the desire to ameliorate iatrogenic diseases, such as BPD and ROP, makes one grasp hopefully at any theory or clinical trial that suggests a role for vitamin E in decreasing the handicaps that patients take with them from the intensive care nursery. On the other hand, when the question of toxicity arises, one tends to be negative, remembering the unfortunate experiences with oxygen, chloramphenicol, sulfisoxazole, and now, E-Ferol Aqueous Solution. We like to think that if this review had been written 2 years ago, our conclusions, based on the analysis of the data, would have been the same. But, probably, in the absence of data on the severe toxicity of one vitamin E preparation, we would have been more liberal in our recommendations for the use of vitamin E in neonatology. At this time, however, any use of supplemental vitamin E beyond the guidelines of the American Academy of Pediatrics cannot be recommended. Nor can the monitoring of blood Vitamin E levels be recommended as an assurance of nontoxic tissue concentrations in sick, premature infants. All physicians caring for premature infants are urged to review their nursery policies to make sure that excessive doses of vitamin E are not being administered. It is hoped that additional clinical trials will provide more definite answers to the questions about the efficacy of vitamin E in ROP and IVH.

Binding properties of glycosylated albumin and acetaldehyde albumin.

Glucose and acetaldehyde react covalently with albumin to form the post-translationally modified group of proteins, the glycosylated albumins and the acetaldehyde albumins, respectively. This study contrasts the binding ability of a major acetaldehyde albumin fraction synthesized in vitro with glycosylated albumin. A microdialysis rate method, using either [14C]monoacetyldiaminodiphenyl sulfone (MADDS), a deputy ligand for bilirubin, or [14C]diazepam, was employed to evaluate binding at these two sites. Our results indicate that prolonged exposure of purified human serum albumin to acetaldehyde results in a major acetaldehyde albumin fraction that lacks the ability to bind MADDS and diazepam. This fraction migrates identically to albumin on SDS polyacrylamide gel electrophoresis, but exhibits microheterogeneity with a more acidic pI band as seen on analytical isoelectric focusing. We suggest that altered drug binding in alcoholics may be partially explained by altered binding ability of acetaldehyde albumins.

Drugs affecting bilirubin uptake by human erythrocyte ghosts.

Drugs known to affect the red blood cell membrane and used clinically in neonates were tested for their ability to cause increased 14C-bilirubin uptake by erythrocyte ghosts. The additional uptake of bilirubin by ghosts in the presence of penicillin G, phenobarbital, furosemide and theophylline may be explained by the effect of these drugs on free bilirubin levels as measured with a horseradish peroxidase assay. In contrast, the effect of chlorpromazine in causing increased bilirubin uptake by ghosts could not be totally explained by either ghost lysis or increased free bilirubin levels, as measured by light scattering, and was due to a direct effect of chlorpromazine on the ghost membrane. Our results demonstrate that drugs may act through different mechanisms in causing increased bilirubin uptake by erythrocytes.

Binding of dapsone and its analogues to human serum albumin.

The binding of dapsone, 4,4'-sulfonylbis(aniline)(1), and its diacetylated derivative, 4,4"'-sulfonylbis(acetanilide)(2), to human serum albumin is reported. To assess the ability of these compounds to displace 4'-[(4-aminophenyl)sulfonyl]acetanilide (3) from albumin, a dialysis rate technique was used. Competition for the bilirubin binding site on albumin was measured with the peroxidase assay. Compounds 1 and 2 strongly displaced both 3 and bilirubin from human serum albumin. The association constants for 1 and 2 with respect to bilirubin binding were 1.29 X 10(3) and 1.15 X 10(4) M-1, respectively. These results suggest that the binding site for 3 and the bilirubin binding site are similar with respect to 1 and 2 and that the binding of dapsone and its derivatives probably does not involve the amino function.

Hematin and bilirubin binding to human serum albumin and newborn serum.

In jaundiced newborn infants, hemolytic disease is considered a risk factor for kernicterus due to the suspected competition between bilirubin and other hemoglobin breakdown products for albumin binding. We have studied the effect of hematin on bilirubin-albumin binding using the peroxidase assay and a light-scattering technique for measuring unbound bilirubin. Our results show that hematin does not affect bilirubin-albumin binding. To determine if other albumin binding functions are affected by hematin, we used a microdialysis rate technique employing two ligands, diazepam and monoacetyldiaminodiphenyl sulfone (MADDS). Hematin does not utilize the diazepam binding function of albumin, but does decrease the albumin binding of MADDS. The results of this study indicate that the MADDS and bilirubin binding functions are not identical. The clinical usefulness of reserve albumin equivalent determination using MADDS is discussed.

Relationship of unbound bilirubin concentration to reserve albumin-binding concentration for bilirubin in human neonatal plasma.

We examined the relationship of plasma unbound bilirubin concentration and reserve albumin-binding concentration for bilirubin in a sample of 545 neonates. Plasma unbound bilirubin concentration and total bilirubin-binding concentration were determined with the peroxidase assay. Contrary to published reports, we found that plasma unbound bilirubin concentration and plasma reserve albumin for bilirubin-binding concentration are highly correlated (r = -0.706; p less than 0.001) and that the relationship between these two parameters is dependent upon the total bilirubin-binding concentration. That these measured parameters correlate in the same manner as predicted for free bilirubin and free albumin by the law of mass action, suggests that these measurements may be meaningful.