Molecular simulation of dynorphin A-(1-10) binding to extracellular loop 2 of the kappa-opioid receptor. A model for receptor activation.

The structure of the second extracellular loop region (EL2) of the kappa-opioid receptor has been explored in an effort to understand the structural basis for dynorphin A binding and selectivity. Application of secondary structure prediction methods and homology modeling resulted in a turn-helix motif for the N-terminal region of kappa-EL2. A similar motif was not predicted for EL2 of either delta or mu opioid receptors. The EL2 helix was further shown to be amphiphilic and complementary to the helical component of dynorphin A. Using a model of the kappa-receptor (Metzger et al. Neurochem. Res. 1996, 21, 1287-1294), including the newly predicted EL2 turn-helix domain, a binding mode is proposed based on helix--helix interactions between hydrophobic residues of EL2 and the helical component of dynorphin A-(1-10). Molecular simulations of the receptor--ligand complex yielded structures in which the tyramine moiety or opioid "message" of dynorphin is bound within a conserved aromatic pocket in the transmembrane domain while the helical portion contacted residues in EL2 and in the extracellular end of transmembrane helices 6 and 7. The model is in general agreement with site-directed mutagenesis data and chimera studies that have identified binding domains in both the EL2 and transmembrane regions of dynorphin A. The results confirm the importance of the opioid "message" displayed by many opioid ligands but also suggest a potential mechanism of receptor activation that may be mediated by EL2 through interactions with the "address" component of dynorphin A.

6 beta-Propynyl-substituted steroids: mechanism-based enzyme-activated irreversible inhibitors of aromatase.

The synthesis and aromatase inhibitory profile of 6 alpha and 6 beta-propargyl androstenedione and estrenedione are described. The targeted compounds 1 and 2 were prepared by addition of the propargyl Gringard to the 5 alpha,6 alpha-epoxy bisketal 6 or the 5 alpha,6 alpha-epoxy diacetate 7 followed by dehydration of the 6 beta-propargyl 5 alpha-hydroxy diones 10 and 11 using thionyl chloride. Treatment of the 6 beta-propargyl analogs 1 and 2 with hydrochloric acid gave the corresponding 6 alpha-propargyl isomers 3 and 4. Inhibitory activity of the synthesized compounds was assessed using a human placental microsomal preparation as the enzyme source and [1 beta-3H]-4-androstenedione as substrate. Under initial velocity assay condition of low product formation, the inhibitors demonstrated potent inhibition of aromatase, with apparent KiS ranging from 10 to 66 nM, with the Km for androstenedione being 55 nM. 6 alpha-Propargylandrost-4-ene-3,17-dione and 6 alpha-propargylestr-4-ene-3,17-dione were found to be potent competitive inhibitors of aromatase (Ki 37 and 66 nM, respectively). On the other hand the 6 beta-propargylandrost-4-ene-3,17-dione (6 beta-PAD) and 6 beta-propargylestr-4-ene-3,17-dione (6 beta-PED) were found to bind to aromatase with an apparent Ki of 10 and 48 nM, respectively, as well as cause rapid time-dependent, first-order inactivation of aromatase in the presence of NADPH, whereas no inactivation was observed in the absence of NADPH. Substrate protects the enzyme from inactivation, but beta-mercaptoethanol does not, suggesting that the 6 beta-propargyl analogs 6 beta-PAD and 6 beta-PED are mechanism-based inactivators of aromatase. Energy-minimization calculations and molecular modeling studies indicate three global minima for each of the 6 beta-propargyl analogs in which one of the conformers is proposed to be responsible for the inactivation of aromatase.

Iodine, thyroid function, and very low birth weight infants.

OBJECTIVE: Research was undertaken to test two hypotheses. First, during the early neonatal period, thyroid function of very low birth weight (VLBW) infants is suppressed by exposure to iodine-containing antiseptic solutions and/or iodized contrast media. Second, this suppression is more pronounced in small for gestational age (SGA) infants. METHODS: Urinary iodine concentration and thyroid function measurements were obtained prospectively from 44 VLBW infants with gestational ages at birth of 30 +/- 2.3 weeks and weights of 1223 +/- 231 g. Eleven of these infants were SGA. The infants were grouped according to iodine exposure: 18 infants had no increased exposure and served as control infants; 9 infants were exposed to an iodine-containing antiseptic (povidone iodine); 12 infants were exposed to an iodized contrast medium (iopamidol); and 5 infants were exposed to both agents. Urinary iodine and serum free triiodothyronine, free thyroxine, and thyrotropin were measured on days 1, 7, 14, 21, and 28 of life. RESULTS: During the period of maximum exposure (days 1 to 7), the concentration of iodine in the urine of study infants was 2 to 4 orders of magnitude greater than that in the urine of control infants (123 +/- 141 micrograms/L). During the subsequent 3 weeks, levels of urinary iodine in study infants returned to levels that were not significantly different from controls. On day 7 of life, iodine-exposed infants had a significantly higher mean thyrotropin level than control infants, whereas on day 28, free triiodothyronine and thyroxine levels were lower. Of the 26 iodine-exposed infants, 6 had transient hyperthyrotropinemia and 2 had transient hypothyroidism. When exposed to iodine, SGA infants had more labile thyroid function than normally grown iodine-exposed or control infants. These SGA infants had significantly lower levels of thyroid hormones in umbilical cord blood, increased production of thyroid hormones on day 14 of life, and lower levels again at 1 month. CONCLUSION: In VLBW infants, the use of iodine-containing antiseptic solutions and iodized contrast media results in massive uptake of iodine that is associated with alterations in thyroid function. It is reasonable to suggest that, whenever possible, iodized products should be avoided in VLBW infants, because their routine use results in exposure to excessive loads of iodine, which can be associated with hyperthyrotropinemia and hypothyroidism.

Ex novo episodes of acute glomerulonephritis and Guillain-Barré syndrome: a case report.

A nine-year-old girl had several ex novo episodes of acute glomerulonephritis with clinical evidence of rapid progression in two of them. Guillain-Barré syndrome was diagnosed 10 days after the second episode of acute glomerulonephritis. Two renal biopsies (performed at about a four-year interval) gave morphological evidence of new episodes of acute glomerulonephritis. To our knowledge this is the first report of an association between ex novo episodes of acute glomerulonephritis and Guillain-Barré syndrome.

Decision making in neonatologia.

The field of neonatology presents a fascinating context in which hugely important decisions have to be made on the basis of physicians' assessments of the long term consequences of various possible choices. In many cases such assessments cannot be derived from a consensual professional opinion; the situation is characterized by a high level of uncertainty. A sample of neonatologists in different countries received a questionnaire including vignette cases for which no clear consensus exists regarding the (probabilistic) prognosis. They were asked to (I) assess the probability of various outcomes (death, severe impairment) and (II) choose a treatment to be offered to the parents. Information on the physicians' professional and socio-demographic characteristics and their ethical "values" was also collected. The goal of this international survey is to understand the prognosis and to analyze decision making by professionals in the context of life and death in medicine. The availability of an identical technology in different social and institutional contexts should help identifying the convergences and differences under consideration. Seventy percent of those invited responded to the questionnaire (International 60-80%). Italian neonatologists seem to be quite pessimistic about the prognosis of infants at high risk of death or long term disabilities, they show a pro-life attitude, but in a certain proportion are willing to change their minds if requested by parents. Furthermore personal opinions predominate in the decision-making process and the contribution of team meeting and/or ethic consultation seem not significantly modify the decisions.

Seizures and transient blindness following intravenous pulse methylprednisolone in children with primary glomerulonephritis.

Two children, 1 with idiopathic nephrotic syndrome and 1 with endo-extracapillary glomerulonephritis, presented an episode of seizures and transient blindness at different times after i.v. pulse methylprednisolone (IVPMP) treatment. Neurological manifestations in patient 1 could be due to hypertension secondary to IVPMP, while the pathogenesis of such manifestations remained difficult to clarify in patient 2. The severity of uremia in patient 2 could be one of the conditions that, in association with the abrupt changes obtained with IVPMP, predispose to neurological manifestations. Careful clinical and biochemical monitoring seems necessary in children with primary glomerulonephritis, other than those transplanted, after IVPMP, and factors predisposing to neurologic sequelae should be further defined.

Growth evaluation in children with acute renal failure of unknown etiology.

We performed a retrospective study on 47 children over 1 year of age with severe acute renal failure (ARF) treated with hemodialysis (HD) at our Center from 1978 to 1986 in order to evaluate the diagnostic and prognostic value of growth indexes at hospital admission as a criterion to distinguish cases of ARF without previous chronic renal failure (CRF) from cases in which CRF was not previously diagnosed. The age of the patients ranged from 17 months to 13 years. The cause of ARF was identified in 41 children; 5 of them remained on HD for different reasons (hemolytic uremic syndrome with arteriolar involvement in 3 cases; renal vein thrombosis in 1; endoextracapillary glomerulonephritis in 1). No apparent cause of ARF was found in the other 6 children who remained on chronic HD. A careful history showed that these 6 children had had uremic symptoms for many years. When height was expressed as height standard deviation score (HSDS), the 6 children with ARF of unknown etiology showed significantly lower HSDS values compared with the other 41 children in whom a cause of ARF was diagnosed (p less than 0.001). In conclusion, growth failure in children requiring HD for ARF of unknown etiology is an important criterion that suggests a previously undiagnosed CRF and thus consequently a negative long-term prognosis.

Accuracy of prenatal ultrasonographic diagnosis of duplex renal system.

Duplex renal system is a rare congenital anomaly of the urinary tract that can be diagnosed in utero. The purpose of this study was to establish the optimal diagnostic criteria for fetal renal duplication in a population undergoing prenatal sonographic screening. Between January 1989 and June 1997 we found 11 cases of duplex renal system, 10 of which were correctly identified in utero at a median gestational age of 28 weeks (range, 20 to 38 weeks), and one of which was a false-negative diagnosis. Prenatal diagnosis of duplex renal system can be made in utero during the second half of pregnancy in the presence of two or more of the following signs: hydronephrosis limited to one pole in a kidney with two separate, noncommunicating renal pelves; ipsilateral megaureter; and ureterocele.

Clinical significance of fetal intracranial hemorrhage.

OBJECTIVE: We reviewed our experience with six consecutive cases of fetal intracranial hemorrhage and the cases published in the English literature in an attempt to devise an original prognostic scoring system for antenatal intracranial hemorrhage. STUDY DESIGN: The series included the cases of fetal intracranial hemorrhage detected at our institution between 1992 and 1994 by transabdominal ultrasonography. In addition, we performed an English literature search (Medline computer search, National Library of Medicine) of all reported cases of a prenatal diagnosis of intracranial hemorrhage. The prenatal ultrasonographic findings were correlated with the clinical outcome, which was divided into (1) normal outcome or mild neurologic sequelae and (2) poor outcome (severe neurologic impairment and fetal or neonatal death). RESULTS: Six cases of intracranial hemorrhage were detected in a population of 6641 pregnancies (0.9/1000) at our institution. Parenchymal involvement was present in three cases. Review of the English literature revealed 35 additional cases with prenatal ultrasonographic findings and postnatal follow-up. The total cases (n = 41) were divided into three groups: (1) isolated intraventricular hemorrhage (n = 20), (2) parenchymal hemorrhage (n = 13), and (3) subdural or subarachnoid hemorrhage (n = 8). Overall, poor outcome was present in 68% of cases, including 45% (9/20) of intraventricular hemorrhage, 92% (12/13) of parenchymal hemorrhage, and 88% (7/8) of subdural or subarachnoid hemorrhage. The heterogeneity of the intraventricular hemorrhage group in both severity of antenatal findings and outcome prompted us to devise a prognostic scoring system based on prenatal ultrasonographic lesions, grouping cohorts with similar outcomes. Outcome was favorable in 100% (5/5) of grade 1 intraventricular hemorrhage cases, in 50% (6/12) of grade 2 cases, and in 0% (0/3) of grade 3 cases. CONCLUSIONS: Fetal intracranial hemorrhage can be classified on the basis of the anatomic location of the intracranial bleeding. The prognosis is poor in nearly 90% of parenchymal and subdural hemorrhages, whereas it is better in the subgroup with intraventricular hemorrhage. The prognostic scoring system we propose for intraventricular hemorrhage may assist the physician in providing patients with prognostic information.

Clinical outcome of mild fetal ventriculomegaly.

OBJECTIVE: Our purpose was to evaluate the outcome of fetuses with mild cerebral ventriculomegaly. STUDY DESIGN: We prospectively collected all cases of mild cerebral ventriculomegaly (transverse diameter of the atrium of the cerebral lateral ventricles between 10 and 15 mm) diagnosed antenatally between January 1990 and December 1996. Associated ultrasonographic abnormalities including markers of aneuploidy, presence of chromosomal anomalies, structural malformations detected at birth, and neurologic outcome were recorded. Outcome information was available on all cases. In addition, published series of cases of fetal mild cerebral ventriculomegaly were reviewed to identify prognostic indicators. RESULTS: Eighty-two cases fulfilled the inclusion criteria: 48 were isolated and 34 were associated with other ultrasonographic markers or anomalies. Among the 45 surviving euploid isolated cases, neurologic follow-up was normal at a mean age of 28 months (range 3 to 72 months). Male fetuses and those with a transverse atrial size <12 mm had a good prognosis. Ventricular atria > or =12 mm were more often associated with other anomalies (56% vs 6%) and, when isolated, with abnormal postnatal neurodevelopment (23% vs 3%). Aneuploidy was present in two cases of isolated mild cerebral ventriculomegaly, both of which were associated with advanced maternal age, and in seven cases associated with other anomalies. CONCLUSIONS: Mild cerebral ventriculomegaly should prompt targeted ultrasonographic examination, inclusive of markers of aneuploidies, visualization of the corpus callosum, and echocardiogram as well as serologic evaluation for congenital infections. In isolated mild cerebral ventriculomegaly genetic counseling should take into account clinical, laboratory, and ultrasonographic findings. A review of the published series suggests that cognitive or motor delay is predominantly mild and that it occurs in about 9% of cases of isolated mild cerebral ventriculomegaly.

Renal effects of cyclosporin A in children treated for idiopathic nephrotic syndrome.

Little data have been published on tubular renal function during cyclosporin A treatment in children without transplants. We studied 12 young subjects (mean age 10 years) with steroid-responsive idiopathic nephrotic syndrome and with signs of steroid toxicity. After achieving remission with prednisone 60 mg/m2, 8 children started cyclosporin A therapy (6 mg/kg/day) (group A) and 4 children were given cyclophosphamide 2.5 mg/kg/day (group B). The latter were considered as controls together with 10 other children with idiopathic nephrotic syndrome in complete remission and off therapy (group C). We monitored creatinine clearance and tubular handling of beta 2-microglobulin, sodium, phosphorus and uric acid for one year. Cyclosporin A induced a decrease in creatinine clearance with a decrease in fractional excretion of beta 2-microglobulin; sodium excretion was similar in the two treated groups and a transient decrease in fractional excretion of uric acid was seen only in patients receiving cyclosporin A. Both groups showed an increased renal threshold phosphate concentration. Our results suggest that in children, cyclosporin A therapy induces a decrease in glomerular filtration rate associated with increased reabsorption activity of proximal tubular cells.

Ultrasonographic differential diagnosis of fetal intracranial interhemispheric cysts.

OBJECTIVE: Ultrasonographic differentiation between intracranial supratentorial interhemispheric pathologic cystlike lesions and those related to physiologic median structures is essential because the latter have no clinical relevance, whereas the former may carry a poor prognosis. We reviewed our experience with 19 consecutive cases of interhemispheric hypoechoic lesions without parenchymal involvement diagnosed between January 1990 and June 1997 to establish their clinical significance and provide prenatal ultrasonographic criteria to distinguish between pathologic cystlike lesions and those related to physiologic midline structures. STUDY DESIGN: All patients underwent targeted prenatal scans of intracranial anatomy to establish the relationship between the fluid collections and the surrounding parenchymal and ventricular structures. In addition, a detailed anatomic survey was performed to rule out associated malformations. Follow-up, including neurologic examination, imaging, autopsy evaluation, or a combination was performed in all cases. Statistical analysis used the Wilcoxon rank sum test, the Fisher exact test, and the chi2 test for trend. P <.05 was considered significant. RESULTS: Cystlike lesions related to physiologic median structures (n = 12) included enlargement of the cavum septi pellucidi (n = 3), enlargement of the cavum vergae (n = 2), and cysts of the velum interpositum (n = 7). These lesions were unilocular and had a median size of 10 mm (range 10-30 mm); they resolved in 5 cases and remained stable in the remainder. They were not associated with overt abnormalities, other than borderline ventriculomegaly in 2 cases. Pediatric follow-up (median 26 months, range 3-84 months) showed normal neurodevelopment in all cases. Pathologic cystlike lesions (n = 7) were significantly larger (median 40 mm, range 10-80 mm, P =.004) and had a significantly worsening trend, growing more at serial prenatal ultrasonographic examinations (P =.039) than fluid collections related to physiologic median structures. Moreover, prenatal ultrasonographic evidence of associated intracranial abnormalities, in the form of partial or total agenesis of the corpus callosum and overt hydrocephalus, was present in 5 of 7 cases of pathologic cystlike lesions and in none of the 12 related to physiologic structures (P =.002). Median gestational age at diagnosis was not different between those with cystlike lesions related to physiologic median structures and those with pathologic lesions (30 and 31 weeks, respectively). Among the latter group, 1 pregnancy was voluntarily terminated, 1 infant died at 4 months of age, 2 infants had neurodevelopmental delay, and 3 infants were neurologically healthy at a mean follow-up of 43 months. Cyst shunting was necessary in 5 of 6 cases. CONCLUSIONS: Interhemispheric cystlike lesions related to physiologic structures can be prenatally distinguished from pathologic fluid collections on the basis of location, cyst size, change in size with time, and absence of associated anomalies.