Mediastinal lymphangioma in an infant

Lymphangioma confined exclusively to the mediastinum occurs rarely in patients under 2 years of age. A 17-month-old girl presented with recurrent respiratory symptoms and signs. Chest radiographs taken at 9 and 17 months of age showed a large mediastinal mass, which had increased in size during the interval. Sonography revealed the mass to be cystic and multiloculated. Magnetic resonance imaging demonstrated a heterogeneous mass lying in the anterior and superior mediastinum and enveloping the great vessels. The child underwent a left thoracotomy and the tumor was almost completely removed. The pathologic diagnosis was cavernous lymphangioma. The postoperative course was uneventful. Lymphangioma, though rare, should be considered in the differential list of mediastinal tumors and cysts in infants.

Long-term outcome of patients with rheumatic fever receiving benzathine penicillin G prophylaxis every three weeks versus every four weeks

OBJECTIVE

To compare the efficacy of injections of 1.2 million units of benzathine penicillin G given every 3 weeks versus every 4 weeks for secondary prevention of rheumatic fever, based on the long-term outcome of patients receiving such prophylaxis.

METHODS

A total of 249 consecutive patients with rheumatic fever, randomly assigned to either a 3-week or a 4-week regimen, were examined every 3 to 6 months, and followed for 794 and 775 patient-years, respectively.

RESULTS

Compliance with each regimen was comparable: 83 (66.9%) of 124 patients in the 3-week group versus 92 (73.6%) of 125 patients in the 4-week group stayed in the program (p > 0.05). Streptococcal infections occurred less frequently in those receiving the 3-week regimen: 7.5 versus 12.6 per 100 patient-years (p < 0.01). Prophylaxis failed in 2 patients receiving the 3-week regimen and in 10 receiving the 4-week regimen (0.25 and 1.29 per 100 patient-years respectively; p = 0.015). Serum penicillin levels were adequate (> or = 0.02 micrograms/ml) in 100 (56%) of 179 samples obtained 21 days after penicillin injection in the 3-week regimen, and in 51 (33%) of 155 samples obtained 28 days after injection in the 4-week regimen (p < 0.01). Of 71 patients with mitral regurgitation in the 3-week regimen, 47 (66%) no longer had the murmur; of 87 patients in the 4-week regimen, 40 (46%) no longer had the murmur (p < 0.05).

CONCLUSIONS

This 12-year controlled study indicates that the outcome of patients with rheumatic fever is better with a 3-week than with a 4-week penicillin prophylaxis regimen. Greater emphasis and more widespread use of the 3-week regimen should be recommended.

A PCR-based marker tightly linked to the nematode resistance gene, Mi, in tomato

A PCR-based codominant marker has been developed which is tightly linked to Mi, a dominant genetic locus in tomato that confers resistance to several species of root-knot nematode. DNA from tomato lines differing in nematode resistance was screened for random amplified polymorphic DNA markers linked to Mi using decamer primers. Several markers were identified. One amplified product, REX-1, obtained using a pair of decamer primers, was present as a dominant marker in all nematode-resistant tomato lines tested. REX-1 was cloned and the DNA sequences of its ends were determined and used to develop 20-mer primers. PCR amplification with the 20-mer primers produced a single amplified band in both susceptible and resistant tomato lines. The amplified bands from susceptible and resistant lines were distinguishable after cleavage with the restriction enzyme Taq I. The linkage of REX-1 to Mi was verified in an F2 population. This marker is more tightly linked to Mi than is Aps-1, the currently-used isozyme marker, and allows screening of germplasm where the linkage between Mi and Aps-1 has been lost. Homozygous and heterozygous individuals can be distinguished and the procedure can be used for rapid, routine screening. The strategy used to obtain REX-1 is applicable to obtaining tightly-linked markers to other genetic loci. Such markers would allow rapid, concurrent screening for the segregation of several loci of interest.

Kinetics of the reduction of cytochrome b5 with mutations in its membrane-binding domain

In an attempt to understand which amino acids in the membrane anchor of cytochrome b5 might be determinants of its ability to support the cytochrome P450-catalyzed oxidation of selected substrates, the synthetic rat cytochrome b5 gene has been mutated by site-directed mutagenesis. The mutant proteins have been expressed in Saccharomyces cerevisiae, purified and assayed for their ability to support the cytochrome P450-catalyzed metabolism of the cytochrome b5 requiring substrate methoxyflurane (G. Vergères and L. Waskell, 1992, J. Biol. Chem. 267, 12583-12591). The rate of reduction of the cytochromes b5 by cytochrome P450 reductase has been examined by stopped-flow spectrophotometry to determine whether an altered rate of reduction of cytochrome b5 could explain the observed activity of cytochrome b5 in the purified reconstituted mixed-function oxidase system. A mutant in which the 22-amino-acid membrane anchor was replaced by a sequence of 22 leucines was unable to support methoxyflurane metabolism in the reconstituted system and was reduced by cytochrome P450 reductase at a rate (k = 4.5 x 10(-3) s-1) slow enough to explain this finding. Comparison of the rate of reduction of this mutant cytochrome b5 in 0.025% Tergitol and 40 microM dilauroylphosphatidylcholine suggests that this slow rate of reduction may be explained partially by aggregation of the polyleucine protein. The Pro115Stop mutant protein, which has been truncated by 19 amino acids in its COOH terminus resulting in a protein with one-half of the putative membrane anchor, supports methoxyflurane oxidation at 12-20% of the rate of the wild type protein. In addition it is reduced by cytochrome P450 reductase at a rate which should be capable of supporting a normal rate of production formation. The fact that the Pro115Stop mutant can be reduced at a rate capable of supporting a normal rate of methoxyflurane oxidation but in fact only supports methoxyflurane oxidation at 30% of the normal rate suggests that the mutant protein is deficient in its interactions with cytochrome P450. The mutant proteins, Pro115Ala and Ala116Pro, behaved essentially as did the wild type protein demonstrating that the presence (Pro115Ala) or absence (Ala116Pro) of an alpha helix in the middle of the putative membrane-binding domain of cytochrome b5 was not a determinant of the interaction of cytochrome b5 with cytochrome P450 reductase and cytochrome P450.(ABSTRACT TRUNCATED AT 400 WORDS)

The function of tyrosine 74 of cytochrome b5

Tyrosine 74, which is part of a hydrophobic patch on the surface of rat cytochrome b5, also forms van der Waals contacts with the heme prosthetic group of the protein. In addition it is a member of an aromatic network of amino acids which includes Phe-35 and the axial ligand, His-39. Because of its strategic location in the protein, the Tyr-74 residue was mutated to a lysine in order to investigate how it affected the interaction of heme with the protein and whether it might be an alternative binding site and an electron transfer path which cytochrome b5 would use with its amphipathic electron transfer partners cytochrome P450 and its corresponding NADPH cytochrome P450 reductase. The mutant protein receives electrons from NADPH cytochrome P450 reductase and provides the second electron to cytochrome P450 to catalyze the metabolism of methoxyflurane, a substrate which requires cytochrome b5 for its metabolism, at the same rate as the wild type protein. The Tyr74Lys mutant exhibits a normal redox potential and spectroscopic properties identical to those of the wild type protein. Under equilibrium conditions in the presence of urea, heme dissociation and denaturation occur simultaneously with a free energy of 3.4 kcal/mol. The free energy of activation of heme dissociation from the wild type protein is 22.7 kcal/mol. The free energy and free energy of activation of the Tyr74Lys mutant are 1.4 kcal/mol less than the wild type values, indicating that the mutant binds heme 10-fold less tightly and dissociates heme 10 times faster than the wild type protein. Heme transfer experiments demonstrate that heme spontaneously dissociates 6 times faster from the mutant than the wild type protein (t1/2 = 1.9 and 11.5 h, respectively). The most likely conformation of Lys-74 in the mutant protein was determined by calculating the Lys-74 rotamer with the minimal energy using an energy-based conformation search method. This conformation was subsequently modeled on the computer graphics. Not unexpectedly, the side chain of Lys-74 is shifted toward the surface of the protein to allow solvation of the positive charge on the epsilon amino group of lysine. This movement of the lysine residue results in the formation of a cavity on the surface of the cytochrome b5 molecule, which exposes a heme methyl and vinyl group to aqueous solvent thereby destabilizing the binding between the protein and its hydrophobic prosthetic heme group.

Cardiovascular and pulmonary effects of betamethasone during midtrimester on fetal rats

In order to elucidate the effects of corticosteroids on fetal hearts during midtrimester, pregnant rats were injected with a daily dose of betamethasone (1 mg/kg) from the 12th day through the 17th day of pregnancy. The fetal cardiovascular and pulmonary systems were studied on the 21st day of pregnancy (term). The treated fetuses showed the following signs of hydrops fetalis: retarded growth, pale, edematous skin, and decreased movement. The thymus and lung displayed prominent hypoplasia. The morphometry of the treated fetuses revealed: decreased right ventricle mass by 37% and decreased left ventricle mass by 29%. We concluded betamethasone had a significant effect on the developing fetal cardiovascular system, inducing hydrops fetalis. Additionally, beta-methasone caused hypoplasia of the thymus and lung.

Obstructed total anomalous pulmonary venous connection

With the advent of echocardiography, total anomalous pulmonary venous connection (TAPVC) can be readily diagnosed without much difficulty. However, noninvasive detection of the presence of pulmonary venous obstruction in TAPVC remains a difficult issue. During a 5.5-year period, 42 patients were found to have TAPVC by catheterization, surgery, and/or autopsy: 17 had supracardiac drainage, 13 paracardiac drainage, nine infracardiac drainage, and three mixed drainage. Obstruction to pulmonary venous drainage was found in 24 patients (57%). Patients with right isomerism tended to have a higher incidence of pulmonary venous obstruction than those with the usual atrial arrangement (80% vs. 44%, p < 0.05). Color Doppler combined with cross-sectional echocardiography provided accurate delineation of drainage sites in 93% cases (39 of 42). Among the 39 cases with correct echocardiographic delineation of the drainage site, obstruction was detected by echocardiography in 22 cases with a sensitivity of 100% (22 of 22) and a specificity of 85% (17 of 20). Therefore, complete echocardiography, including cross-sectional images and color Doppler proved to be a reliable tool in the detection of drainage sites and pulmonary venous obstruction in TAPVC.

Random Amplified Polymorphic DNA Analysis of Heterodera cruciferae and H. schachtii populations

Heterodera schachtii and H. cruciferae are sympatric in California and frequently occur in the same field upon the same host. We have investigated the use of polymerase chain reaction (PCR) amplification of nematode DNA sequences to differentiate H. schachtii and H. cruciferae and to assess genetic variability within each species. Single, random oligodeoxyribonucleotide primers were used to generate PCR-amplified fragments, termed RAPD (random amplified polymorphic DNA) markers, from genomic DNA of each species. Each of 19 different random primers yielded from 2 to 12 fragments whose size ranged from 200 to 1,500 bp. Reproducible differences in fragment patterns allowed differentiation of the two species with each primer. Similarities and differences among six different geographic populations of H. schachtii were detected. The potential application of RAPD analysis to relationships among nematode populations was assessed through cluster analysis of these six different populations, with 78 scorable markers from 10 different random primers. DNA from single cysts was successfully amplified, and genetic variability was revealed within geographic populations. The use of RAPD markers to assess genetic variability is a simple, reproducible technique that does not require radioisotopes. This powerful new technique can be used as a diagnostic tool and should have broad application in nematology.

Tuberous sclerosis with cardiac rhabdomyoma manifested by fetal bradycardia: report of a case

This is a case of neonatal tuberous sclerosis associated with cardiac rhabdomyoma and manifested by fetal cardiac arrhythmia-bradycardia. The prenatal echocardiography showed multiple cardiac tumors which occupied the left and right ventricles. The largest one measured 5.2 cm in diameter. It was found to be 4.5 x 4.1 x 3.5 cm in size at autopsy. A postnatal cranial echogram showed multiple subependymal nodules. The patient expired after 7 hours of life. The autopsy findings confirmed the diagnosis. The mother of the patient had adenoma seb'aceum on the face and an ungual fibroma on the left little finger. Cranial computerized tomography revealed a small calcified tubercle.

Promotion of extended-release niacin tablets at a Veterans Affairs medical center

A program to modify the prescribing of antilipemic agents by promoting the use of extended-release niacin tablets is described. Between December 1987 and August 1988, pharmacists at a 1188-bed Veterans Affairs medical center observed a large increase in the number of outpatient prescriptions for antilipemic agents. In an attempt to control costs, a program to promote the use of extended-release niacin tablets for treating hyperlipemia was conducted during August and September 1988. Various educational materials on niacin were distributed to physicians. A display on therapy of hyperlipemia was featured at the monthly drug fair, and articles on niacin were presented during a journal club meeting of ambulatory-care clinicians. Pharmacists succeeded in having extended-release niacin tablets placed on the formulary in September. Data on the number of prescriptions filled for antilipemic agents were collected before and after the niacin promotional program. The number of prescriptions filled for extended-release niacin 500-mg tablets increased steadily during a six-month study period after the program ended; the number of prescriptions filled for regular niacin decreased by 50%. As prescribing of extended-release niacin increased, prescribing of colestipol, gemfibrozil, and probucol declined. The promotional program was well received by most of the medical staff. A program of education and formulary management successfully changed physician prescribing habits for antilipemic agents.

45,XO/46,XY in a newborn with the stigmata of Turner syndrome: report of one case

A newborn with ambiguous external genitalia and the stigmata of Turner syndrome presented with the following features: short stature, hypertelorism, bilateral epicanthal folds, ptosis, low-set ears with prominent auricles, high-arched palate, low posterior hairline, webbed neck, broad and short chest, widely-spaced and hypoplastic nipples and clitoris-like phallus with hypospasdias. He also had patent ductus arteriosus, the secundum type of atrial septal defect and mitral stenosis. Chromosomes of peripheral blood showed mosaicism of cells with 45,XO/46,XY. An exploratory laparotomy was performed at five months of age. The right side ovotestis-like gonad was removed. The left side gonad in the scrotum was normal. No pathological gonadoblastoma was found.

Effect of monovalent measles and trivalent measles-mumps-rubella vaccines at various ages and concurrent administration with hepatitis B vaccine

To determine the most suitable vaccination schedule in developing countries, a study was conducted to reevaluate the immunogenicity of monovalent measles vaccine and trivalent measles-mumps-rubella vaccine at different ages. The success rate of measles vaccination was 84% at 9 months, 88% at 12 months and 100% at 15 months of age. Vaccination with measles vaccines at 9 and 15 months of age was also 96% immunogenic. Most vaccinees (16 of 17) not responding to the first measles vaccine before 1 year of age developed measles antibody with another shot of vaccine after 15 months of age. Trivalent measles-mumps-rubella vaccine worked well in children ages 14 to 18 months. Administering trivalent vaccine and hepatitis B vaccine concurrently at 1 year of age, rubella and mumps antibodies developed in more than 95% of vaccinees, while measles antibody was detected in 88%. Responses to hepatitis B vaccine in this situation were good; 89% of vaccinees developed antibody against hepatitis B surface antigen (greater than or equal to 10 mIU/ml) and the geometric mean titer was 362.49 mIU/ml. In summary vaccination twice at 9 and 15 months is effective and is a useful regimen in developing countries where measles is still endemic. Trivalent vaccine and hepatitis B vaccine will not interfere with each other when given together at 1 year of age.

Fetal cardiovascular cross-sectional morphology of tetralogy of Fallot in rats

In order to clarify cross-sectional morphology of tetralogy of Fallot in the fetus, 202 rat fetuses with tetralogy of Fallot induced by maternal administration of bis-diamine were studied using cesarean section, the whole body freezing method and by photographing cross sections of the fetal heart on a freezing microtome. Some characteristic features such as large subaortic ventricular septal defects, aortic overriding over the ventricular septum, aortomitral fibrous continuity, and narrow infundibulum and pulmonary valve were found. Moreover, three subtypes were noticed. In classic tetralogy of Fallot with stenotic infundibulum, the size of the pulmonary arteries was smaller in proportion to the infundibular stenosis. In the second type with absent infundibular septum and severe valvular pulmonary stenosis, the pulmonary arteries were most hypoplastic. In the third type with absent pulmonary valve, the pulmonary arteries were dilated forming aneurysms. In the last type only, ventricles were dilated and grossly hypertrophic.

The effects of selected fungicides and insecticides on growth and thebaine production of Papaver bracteatum

The fungicides benlate, maneb, and captan depressed plant growth, thebaine concentration, and thebaine yield per plant when administered chronically to Papaver bracteatum. The chronic administration of dicofol inhibited plant growth and thebaine yield per plant, but did not affect thebaine concentration. Malathion and pyrethrins had no adverse effects on either plant growth or thebaine content.

Quantitative determination of thebaine in Papaver bracteatum by high-pressure liquid chromatography

A method is described for the quantitative analysis of thebaine from Papaver bracteatum, using a single high-pressure liquid chromatographic column. The procedure gives base-line separation of thebaine without the need for gradient elution equipment, and can be completed within 12 min. Thebaine isolated by this technique was shown to be pure, regardless of the age of plant or plant part from which it was obtained.