Unilateral Fontan operation for tricuspid atresia

A 12-year-old child with tricuspid atresia and acquired hypoplasia of the left pulmonary artery was successfully treated with unilateral Fontan operation. Angiography at age 2 months had shown a normal left pulmonary artery, and a modified Potts shunt was performed. An emergency central shunt was required a year later. Reinvestigation 5 years after the initial operation revealed severe hypoplasia of the left pulmonary artery.

X-ray crystallographic studies on hexameric insulins in the presence of helix-stabilizing agents, thiocyanate, methylparaben, and phenol

Three X-ray crystallographic studies have been carried out on pig insulin in the presence of three ligands, thiocyanate, methylparaben (methyl p-hydroxybenzoate), and phenol. In each case, rhombohedral crystals were obtained, which diffracted to 1.8, 1.9, and 2.3 A, respectively. Each crystal structure was very similar to that of 4-zinc pig insulin, which was used as a starting model for PROLSQ refinement (Collaborative Computational Project, Number 4, 1994). The R factors for the refined structures of thiocyanate insulin, methylparaben insulin, and phenol insulin were 19.6, 18.4, and 19.1, respectively. Each crystal structure consists of T3R3f insulin hexamers with two zinc ions per hexamer. In the R3f trimer of the thiocyanate insulin hexamer, one thiocyanate ion is coordinated to the zinc on the hexamer 3-fold axis, but there is no evidence of zinc ion binding in the off-axis zinc ion sites seen in the 4-zinc pig insulin structure. In the methylparaben insulin and phenol insulin hexamers, the phenolic ligands are bound at the dimer-dimer interfaces in the R3f trimers in a manner similar to that of phenol in R6 phenol insulin. The binding of methylparaben appears to make the hexamer more compact by drawing the A and the B chains closer together in the binding site. In all three structures presented herein, the conformations of the first three residues of the B chain in the R3f trimer are extended rather than alpha-helical, as is seen in R6 phenol insulin. The energetics of ligand binding in the insulin hexamer are discussed.

Determinants of the high-methionine trait in wild and exotic germplasm may have escaped selection during early cultivation of maize

The 18 kDa high-methionine delta-class zein gene from maize has been cloned, and its regulation, structure, and map position studied. These studies have shown that (i) zein genes may also contain tryptophan and lysine codons, (ii) the 18 kDa and the related 10 kDa zein gene are coordinately regulated, but their products accumulate to different levels in a genotype-dependent manner, (iii) the duplication of delta-zein genes probably involved unequal crossing over, (iv) no copy correction in either direction has occurred from teosinte to modern corn, and (v) the duplication of of the 18 kDa zein gene probably occurred before the tetraploidization of a progenitor chromosome. The work shows that important nutritional quality determinants like the high-methionine seed proteins are abundant in several exotic and wild corn varieties and low in most of the inbreds screened. The lack of a selectable phenotype for such quality traits during initial domestication and breeding of corn would have eliminated cis and trans regulatory determinants from the germplasm used in modern corn breeding. Examples of the high-methionine delta-class zeins shown here may be generally applicable in explaining the low nutritional quality of most present-day corn grown.

Site-specific factor involved in the editing of the psbL mRNA in tobacco plastids

In tobacco plastids, functional psbL mRNA is created by editing an ACG codon to an AUG translation initiation codon. To determine if editing may occur in a chimeric mRNA, the N-terminal part of psbL containing the editing site was translationally fused with the aadA and kan bacterial genes. The chimeric constructs were introduced into the tobacco plastid genome by targeted gene insertion. Editing of the chimeric mRNAs indicated that the 98 nt fragment spanning the psbL editing site contains all cis information required for editing. Expression of the chimeric gene transcripts led to a significant decrease in the editing efficiency of the endogenous psbL mRNA. However, the efficiency of editing in the transplastomic lines was unchanged for four sites in the rpoB and ndhB mRNAs. Reduced efficiency of psbL editing, but not of the other four sites, in the transplastomic lines indicates depletion of psbL-specific editing factor(s). This finding implicates the involvement of site-specific factors in editing of plastid mRNAs in higher plants.

RFLP mapping of the maize dzr1 locus, which regulates methionine-rich 10 kDa zein accumulation

The dzrl locus in maize posttranscriptionally regulates the accumulation of methionine-rich 10 kDa zein in the endosperm. An allele of this locus present in the inbred line BSSS53, dzrl + BSSS53, conditions several-fold higher accumulation of the 10 kDa zein in comparison with standard inbred lines, leading to enrichment of methionine content in BSSS53 by 30%. In a population segregating for high and low 10 kDa zein, dzr1 + BSSS53 was found tightly to cosegregate with a 22 kDa zein gene cluster, belonging to the Z1C subfamily of alpha-zeins that is located on chromosome 4S. One member of this gene cluster, azs22/6, was estimated to be located less than 0.4 cM from dzr1 + BSSS53, while three other 22 kDa zein genes mapped 3.4 cM away. Restriction fragment length polymorphism (RFLP) mapping of dzr1 was conducted using additional maize DNA markers and orthologous rice DNA markers. One maize marker, php20725, was identified that mapped 1.1 cM from dzr1, proximal to the centromere. Another marker derived from rice, rz329, mapped 6.6 cM distal to dzr1. Pulsed-field gel electrophoresis (PFGE) of the 22 kDa zein cluster showed that probably all copies of the 22 kDa zein genes are present within a 200 kb SalI fragment. The recombination frequency within this cluster was estimated to be 20-fold higher than that predicted for the maize genome.

A case-control study of reproductive risk factors associated with cervical cancer

Using the logistic-regression technique, a hospital-based case-control study of 177 married women with invasive squamous-cell cervical cancer and 149 hospital-visiting controls enabled evaluation of selected reproductive factors as risks. Early age at marriage was found to be the single best predictor of the disease status. However, those who married late but gave birth to a large number of children were generally found to be suffering from cervical cancer. The results support the hypothesis that it is not so much parity per se that enhances the risk, but the rapidity of multiple pregnancies that matters. Logistic analysis also revealed the independent influence of birth interval on the risk of cervical cancer. These findings warrant serious consideration in future studies, given the obvious implications for prevention. Other implications for the prevention of cervical cancer are briefly discussed.

Delirium after cataract extraction: a prospective study

A prospective study of 350 consecutive in-patients undergoing cataract extraction revealed the incidence of postcataract extraction delirium to be 1.7%. While in one case the delirium was due to anticholinergic toxicity, in the remaining 5 cases no organic cause was evident. Sensory deprivation was present in 3 patients. In addition to organic causes sensory deprivation was found to be an important cause of postcataract extraction delirium.

Allele-specific parental imprinting of dzr1, a posttranscriptional regulator of zein accumulation

Parental imprinting describes the phenomenon of unequivalent gene function based on transmission from the female or male parent. We have discovered parental imprinting of an allele of the dzr1 locus that posttranscriptionally regulates the accumulation of 10-kDa zein in the maize endosperm. The imprinted allele of MO17 inbred origin, dzr1 + MO17, conditions low accumulation of the 10-kDa zein and is dominant when transmitted through the female but recessive when transmitted through the male. Analyzing endosperms with equal parental contributions of dzr1 + MO17 ruled out the possibility that the unequivalent phenotype of dzr1 + MO17 was due to parental dosage imbalance in the triploid endosperm. Second-generation studies show that the dominant or recessive phenotype of dzr1 + MO17 is determined at every generation based on immediate parental origin with no grandparental effect.

Cloning of a pig glucose transporter 4 cDNA fragment: use in developing a sensitive ribonuclease protection assay for quantifying low-abundance glucose transporter 4 mRNA in porcine adipose tissue

A 246-bp fragment of porcine glucose transporter 4 (GLUT4) cDNA was cloned by polymerase chain reaction (PCR) from porcine adipose tissue RNA. Nucleotide sequences 1-138 and 139-246 of the GLUT4 cDNA share 78% sequence identity with exon 4a and 91% sequence identity with exon 4b of the human GLUT4 gene, respectively. The GLUT4 cDNA fragment was subcloned into pGEM-4Z vector to synthesize a highly specific riboprobe that hybridized only to human GLUT4 cDNA but not to human glucose transporter 1 (GLUT1) cDNA. Northern blot analysis of total RNA revealed the presence of a single transcript of 2.8 kb in porcine adipose tissue. Cloning a fragment of the GLUT4 cDNA enabled us to develop a ribonuclease protection assay for detecting porcine GLUT4 mRNA. The ribonuclease (RNase) protection assay is highly reproducible and retains a sensitivity level to as little as 2 pg of GLUT4 mRNA. The standard curve was linear between 2 and 128 pg of sense-strand GLUT4 RNA (r = .994). The ability to detect small quantities of GLUT4 mRNA is important when the abundance of GLUT4 mRNA is low and the quantity of tissue is limiting (e.g., when RNA is extracted from cultured adipose tissue). When porcine adipose tissue explants were cultured in the presence of insulin (10 ng/mL), GLUT4 mRNA abundance was increased. Development of a sensitive assay to quantify GLUT4 mRNA in porcine adipose tissue will enable us to conduct studies to increase our understanding of the molecular mechanisms by which porcine somatotropin (pST) regulates GLUT4 gene expression.

The stimulation by dendritic cells of host-versus-graft reactivity in vivo

Dendritic cells (DC) isolated from peripheral intestinal lymph of inbred Wistar rats were injected into the hind footpads of Hooded CBH/Cbi rats. Administration of 10(4) and 5 x 10(5) allogeneic DC produced approximately six-fold increase in popliteal node weight. This is only marginally greater than that caused by similar doses of syngeneic DC and about 30% greater than that caused by allogeneic mononuclear cells. The data indicated that allogeneic DC were not effective stimulators of host-versus-graft reactions in this assay.

Mechanisms by which somatotropin decreases adipose tissue growth

When growing pigs are treated daily with recombinantly derived porcine somatotropin (pST) for 30-60 d there is a dose-dependent decrease in lipid accretion. Maximal doses of pST can reduce lipid accretion by as much as 70%. The reduction in lipid accretion occurs because of a marked decrease in glucose transport and lipogenesis that is the result of a pST-dependent decrease in the ability of insulin to stimulate these processes in the adipocyte; lipolysis is not affected. The decrease in insulin sensitivity is not due to a decrease in insulin binding or insulin receptor kinase activity. Little is understood about the somatotropin (ST) intracellular signal pathway(s) that mediate the biological effects of ST. These effects are chronic rather than acute as was previously believed. This pattern likely reflects that ST decreases transcription of important insulin-responsive genes such as the muscle-adipose tissue transporter gene (GLUT4) and key lipogenic enzymes.

Immunomodulation and 'Ia' variability in dendritic lymph cells: a radiobinding immunoassay versus immune response study

A radiobinding immunoassay technique has been employed to determine the 'Ia' antigens localised on the surface of the following immunocompetent cells: Dendritic lymph cells from peripheral intestinal lymph, peritoneal macrophages and thymocytes all gathered from sheep red blood cell treated animals, and the irradiated cell controls. A corresponding popliteal lymph node assay was performed following the administration of the same cells into the foot pad of allogeneic rats to determine the comparative immunogenic responsiveness. Dendritic lymph cells in free flowing lymph of sensitised, irradiated and control animals showed a significantly higher 'Ia' content and consequently greater immunogenicity as measured by the popliteal lymph node assay. Sheep red blood administration in animals may stimulate surface 'Ia' expression in lymph derived dendritic cells resulting in higher immune-responsiveness.