Lack of association between IL-6-174G/C gene polymorphism and Chagas disease.

The aim of this study was to investigate the role of the IL-6-174G/C gene polymorphism in susceptibility/resistance to Trypanosoma cruzi infection in two independent cohorts from Colombia and Peru. We determined the IL-6-174G/C genotypes in a sample of 399 seronegative individuals and 317 serologically positive patients from Colombia and Peru. All individuals are from regions where T. cruzi infection is endemic. No statistically significant differences in the frequency of IL-6-174G/C gene polymorphism between chagasic patients and controls or between asymptomatic and individuals with cardiomyopathy were observed. Our results do not support an evidence for a major role contribution of this IL-6 gene polymorphism in the susceptibility to or clinical manifestations of Chagas disease in these studied cohorts.

International shipping of fumonisins from maize extracts on C18 sorbent.

Fumonisins are mycotoxins found in maize. In developing countries, the resources required for analysis are often lacking, and the shipping of maize between countries can be difficult since the importation of plant materials requires permits/inspection to prevent the entry of pests that frequently infest maize. A simple, safe and legal method for shipping maize extracts to the USA was needed to conduct a survey of fumonisins in Central America. The objective was to develop a method for isolating and shipping maize extracts for fumonisin analysis so as to facilitate a survey of fumonisin exposure. The results indicate that fumonisins in acetonitrile:water extracts of maize can be isolated on C18 cartridges, held for at least 3 days at 22 degrees C and then an additional 4 days at 4 degrees C before elution and analysis with no losses. This method allows the importation and analysis of maize samples from foreign locations without complications from international safety concerns.

Folinic acid-responsive neonatal seizures.

We report three cases of folinic acid-responsive intractable neonatal seizures. All patients were born at term following normal gestation and delivery. In the first infant, seizures began on the 5th day of life and were unresponsive to phenobarbital, pyridoxine, and valproate, but stopped within 24 hours of initiation of folinic acid treatment at the age of 6 months. Her sibling had died at age 6 months with intractable seizures. In the second infant, seizures began in the 2nd hour of life. These were initially controlled with phenobarbital; however, at 3 months of age she developed status epilepticus refractory to anticonvulsants, steroids, and pyridoxine and she required repeated induction of pentobarbital coma. Seizures stopped within 24 hours of starting folinic acid. Seizures and encephalopathy were noted in the third infant on the 2nd day of life. These were controlled with phenobarbital, but at 8 weeks of age seizures recurred and were difficult to control despite the addition of phenytoin. Immediately after folinic acid was initiated the seizures stopped. Breakthrough seizures in all patients have responded to increases in folinic acid; two of the three remain on standard anticonvulsants. All patients have global developmental delay. Cranial magnetic resonance imaging in the second patient shows diffuse atrophy, and in the third patient shows increased signal on T2 images in the white matter of the frontal and parietal lobes. Analysis of cerebrospinal fluid from these patients using high-performance liquid chromatography with electrochemical detection has consistently revealed an as-yet unidentified compound, which can be used as a marker for this condition. We suggest that cerebrospinal fluid be analyzed for the presence of this compound and a trial of folinic acid be considered in neonates with unexplained early onset intractable seizures.

Early diagnosis of subependymal giant cell astrocytoma in patients with tuberous sclerosis.

We present 19 patients with tuberous sclerosis complex and subependymal giant cell astrocytoma. The mean age at the time of tumor diagnosis was 9.4 years (range, 1.5 to 21 years). Computed cranial tomography (CT) or cranial magnetic resonance imaging (MRI) identified the lesion which was resected in all cases. Seven patients had hydrocephalus and there was an interval increase in the tumor size or a large tumor without hydrocephalus in 12 patients. Surgical criteria included: (1) presence of hydrocephalus; (2) interval increase in tumor size; (3) new focal neurologic deficit attributable to the tumor; and/or (4) symptoms of increased intracranial pressure. Eight patients were identified through a surveillance program involving annual computed cranial tomography. All of these eight patients had their tumor removed prior to the development of symptoms, none had neurologic deficits which persisted after surgery, and none has so far developed recurrent subependymal giant cell astrocytoma. In contrast, of the 11 patients from the non-surveillance group 7 were symptomatic at tumor diagnosis, 1 had a complicated postoperative course, 2 developed recurrent giant cell astrocytoma, and 1 had an extensive lesion that could not be completely excised. Periodic cranial imaging may help to identify subependymal giant cell astrocytomas in tuberous sclerosis patients before they become symptomatic. Earlier diagnosis and treatment could reduce surgical morbidity and the risk of tumor recurrence.

Leukotriene C4-stimulated contractions in bullfrog lung are affected by cold acclimation and calcium antagonists.

Leukotriene C4 (LTC4) contracts isolated bullfrog lung. This study examined effects of cold-acclimation and the involvement of extracellular and intracellular Ca++ on the contractile response to LTC4. The response to LTC4 was greater in lungs from warm-acclimated (22 degrees C) frogs compared with cold-acclimated (5 degrees C) frogs at incubation temperatures of both 22 degrees C and 5 degrees C. LTC4, LTC5, and N-methyl LTC4 were equally effective in stimulating lung contraction at concentrations from 1-100 nM. Nicardipine (3 microM) partially antagonized the response to LTC4, but verapamil, nifedipine, or nitrendipine at the same concentration was ineffective. Ethylene glycol tetraacetic acid (EGTA, 0.3 mM) prevented the response to 30 nM LTC4, but the response was restored when the lung was retested in EGTA-free medium containing Ca++, suggesting that extracellular Ca++ was involved in the response. Caffeine (10 mM) or thapsigargin (1 mM) inhibited the responses to LTC4, suggesting a role for intracellular Ca++ in the contraction.

Leukotriene B4 and leukotriene B5 have binding sites on lung membranes and cause contraction of bullfrog lung.

Leukotriene (LT)B4 and LTB5 cause contraction of isolated bullfrog lung. LTB4 receptors were characterized in membranes prepared from bullfrog lung. Binding of [3H]LTB4 was maximal at 5 min and was reversible with the addition of 1000-fold excess LTB4. Scatchard analysis indicated a single class of binding sites with a Kd of 2.22 nM and a Bmax of 1228.86 fmol/mg protein. The Kd and the Bmax values in the presence of guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) were 2.76 nM and 1289.61 fmol/mg protein, respectively. The Ki values for LTB4, LTB5 and 20(OH)-LTB4 were 5.5, 30.5 and 144.0 nM, respectively, whereas 20(COOH)-LTB4 was ineffective in preventing binding of [3H] LTB4 from 10(-9) to 10(-5) M. The peptide leukotrienes LTC4, LTD4 and LTE4 failed to inhibit the specific binding of [3H]LTB4. GTP gamma S in concentrations from 10(-10) to 10(-4) M did not affect the binding of 5 nM [3H]LTB4. Neither the mammalian LTD4 antagonist LY171883 nor the mammalian LTB4 antagonist LY255283 was an effective competitor for the bullfrog lung LTB4 receptor. In addition, sulfhydryl-modifying reagents NEM and PCMP did not affect LTB4 binding as they do in mammalian membrane preparations. The LTB4 receptor shows some differences from the described mammalian receptor. The cell type containing the LTB4 receptor remains to be determined.

Characterization and localization of leukotriene C4 receptors in bullfrog lung.

Specific binding sites for [3H]leukotriene C4, ([3H]LTC4) were characterized in lung membrane preparations and localized to the septa of lung tissue from the American bullfrog (Rana catesbeiana). Binding assays were carried out at 23 degrees C for 30 min in the presence of serine (5 mM)-borate (10 mM) to prevent metabolism of LTC4 to LTD4. Specific binding reached steady state within 10 min and was completely reversible with the addition of 1000-fold excess unlabeled LTC4. Scatchard analysis predicted a single class of binding sites with a Kd of 55.7 nM and a Bmax of 61.9 pmol/mg protein. The Hill coefficient was 0.958. LTC4 was the most potent inhibitor of [3H]LTC4 binding, with a Ki of 33 nM. LTD4 and LTE4 are less potent inhibitors, with Ki values of 3350 and 5979 nM, respectively. Mammalian LTD4 antagonists LY171883, L-649,923 and ICI 198,615 only displaced [3H]LTC4 specific binding at concentrations in excess of 1 x 10(-4) M. Guanosine 5' triphosphate and its analog guanyl-5'-yl-imidodiphosphate did not affect specific binding of [3H]LTC4, suggesting that a Gi protein is not involved in the LTC4 transduction mechanism. Glutathione, S-decyl-glutathione and hematin had Ki values of 35,000, 280 and 29,000 nM, respectively, suggesting the binding site is not the enzyme LTC4-synthase. LTC4 contracted lung strips, with S-decyl-glutathione a partial agonist. Computer-enhanced autoradiographs localized the binding sites to the smooth muscle regions of the septa in lung tissue. These data suggest that LTC4 binds to distinct receptors in bullfrog lung.