Anisocoria: Realities, Recognition, and Remedial Aspects

The realities, recognition, and remedial aspects of anisocoria at the bedside were highlighted by Adhikari et al.,¹ which is almost similar to an earlier report from India.² Since this condition involves patient safety and clinical assessment, we would like to touch upon 3 Ps (physiological, pathological, and pharmacological) of anisocoria. First and foremost is to elicit a thorough clinical history and then to assess the case in detail which not only rules out injuries, infections, instillation, or ingestion of medicines and instigating mechanisms but also helps rule out various other life-threatening conditions.

You bet-cha: a novel family of transcriptional regulators

The BET proteins are a novel class of transcriptional regulators whose members can be found in animals, plants and fungi. Founding members are Human RING3, Drosophila Fsh and yeast Bdf1p. BET proteins are distinguished by an N-terminal bromodomain or bromodomains and an ET domain. As predicted by the presence of the bromodomain(s), these proteins have been found to be associated with chromatin. The poorly characterized ET domain functions as a protein-protein interaction motif and may be part of a serine-kinase activity. Other regions ("modular domains"), which are conserved only in certain BET proteins, are likely to provide sub-family specific functions. Genetic, biochemical and molecular techniques have implicated BET proteins in functions as diverse as meiosis, cell cycle control and homeosis. The data suggest that BET proteins may modulate chromatin structure and affect transcription via a sequence-independent mechanism. This review will attempt to summarize current research on BET proteins and envision where future research is likely to lead.

A genetic screen of the Drosophila X chromosome for mutations that modify Deformed function

We have screened the Drosophila X chromosome for genes whose dosage affects the function of the homeotic gene Deformed. One of these genes, extradenticle, encodes a homeodomain transcription factor that heterodimerizes with Deformed and other homeotic Hox proteins. Mutations in the nejire gene, which encodes a transcriptional adaptor protein belonging to the CBP/p300 family, also interact with Deformed. The other previously characterized gene identified as a Deformed interactor is Notch, which encodes a transmembrane receptor. These three genes underscore the importance of transcriptional regulation and cell-cell signaling in Hox function. Four novel genes were also identified in the screen. One of these, rancor, is required for appropriate embryonic expression of Deformed and another homeotic gene, labial. Both Notch and nejire affect the function of another Hox gene, Ultrabithorax, indicating they may be required for homeotic activity in general.

A model for extradenticle function as a switch that changes HOX proteins from repressors to activators

The Drosophila EXD protein and its mammalian counterparts, the PBX proteins, have been proposed to function in HOX target selectivity. Here we show that exd function is required for the autoactivation phase of Dfd expression in the posterior head. Mutations that change the affinity of a small autoactivation element for EXD protein result in corresponding changes in the element's embryonic activity. Our data suggest that the EXD and DFD proteins directly activate this element in maxillary cells without cooperatively binding to a specialized heterodimer binding site. Based on the types of homeotic transformations and changes in gene expression observed in exd mutant embryos, we propose a new model for EXD/PBX action in which these proteins are required for HOX protein transcriptional activation functions, but dispensable for HOX transcriptional repression functions. Although the selection of a specific target gene by a HOX protein versus another may be explained in some cases by the selective modulation of HOX binding specificity by EXD, we favor the idea that EXD interacts in a more general sense with most HOX proteins to switch them into a state where they are capable of transcriptional activation.

Ftz-F1 is a cofactor in Ftz activation of the Drosophila engrailed gene

The fushi tarazu pair-rule gene is required for the formation of alternating parasegmental boundaries in the Drosophila embryo. fushi tarazu encodes a homeodomain protein necessary for transcription of the engrailed gene in even-numbered parasegments. Here we report that, within an engrailed enhancer, adjacent and conserved binding sites for the Fushi tarazu protein and a cofactor are each necessary, and together sufficient, for transcriptional activation. Footprinting shows that the cofactor site can be bound specifically by Ftz-F1, a member of the nuclear receptor superfamily. Ftz-F1 and the Fushi tarazu homeodomain bind the sites with 4- to 8-fold cooperativity, suggesting that direct contact between the two proteins may contribute to target recognition. Even parasegmental reporter expression is dependent on Fushi tarazu and maternal Ftz-F1, suggesting that these two proteins are indeed the factors that act upon the two sites in embryos. The two adjacent binding sites are also required for continued activity of the engrailed enhancer after Fushi tarazu protein is no longer detectable, including the period when engrailed, and the enhancer, become dependent upon wingless. We also report the existence of a separate negative regulatory element that apparently responds to odd-skipped.

DNA-binding specificity of the fushi tarazu homeodomain

The fushi tarazu (ftz) gene of Drosophila melanogaster encodes a homeodomain-containing transcription factor that functions in the formation of body segments. Here we report an analysis of the DNA-binding properties of the ftz homeodomain in vitro. We provide evidence that the homeodomain binds to DNA as a monomer, with an equilibrium dissociation constant of 2.5 x 10(-11) M for binding to a consensus binding site. A single ftz binding site occupies 10 to 12 bp, as judged by the ability of protein bound at one site to interfere with binding to an adjacent site. These experiments also demonstrated a lack of cooperative binding between ftz homeodomains. Analysis of single-nucleotide substitutions over an 11-bp sequence shows that a stretch of 6 bp is critical for binding, with an optimal sequence of 5'CTAATTA3'. These data correlate well with recent structural evidence for base-specific contact at these positions. In addition, we found that sequences flanking the region of direct contact have effects on DNA binding that could be of biological significance.

Effects of sevoflurane and isoflurane on cardiac and coronary dynamics in chronically instrumented dogs

To assess the hemodynamic properties of the new inhalational anesthetic sevoflurane, 22 dogs were chronically instrumented for measurement of heart rate, aortic, left ventricular and left atrial pressures, cardiac output, and coronary blood flow. Dogs were randomly assigned to two groups, receiving either 1.2 and 2 MAC of sevoflurane (n = 11) or isoflurane (n = 11). At 1.2 and 2 MAC, sevoflurane produced an increase in heart rate (+60 +/- 12% and +54 +/- 9%, respectively), dose-dependent aortic hypotension (-22 +/- 4% and -38 +/- 4%, respectively), systemic vasodilation (-22 +/- 5% and -19 +/- 5%, respectively), dose-dependent decrease in stroke volume (-31 +/- 6% and -48 +/- 4%, respectively), and left ventricular dP/dt (-40 +/- 4% and -61 +/- 10%, respectively). Cardiac output decreased only at 2 MAC (-17 +/- 6%). Finally, coronary blood flow increased at 1.2 MAC of sevoflurane (+29 +/- 8%). Except for heart rate, sevoflurane and isoflurane produced similar effects. At 1.2 MAC, sevoflurane produced a greater increase in heart rate than isoflurane (+60 +/- 12% vs. +33 +/- 9%). The authors conclude that, except for heart rate, the effects of sevoflurane on cardiac function and coronary blood flow are almost identical to those induced by isoflurane in the chronically instrumented dog.

Isolation and complete sequence of a functional human glyceraldehyde-3-phosphate dehydrogenase gene

Glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.2.12) (GAPDH) mRNA levels, protein, and enzymatic activity increase in 3T3-F442A adipocytes after exposure to physiological concentrations of insulin (Alexander, M., Curtis, G., Avruch, J., and Goodman, H. (1985) J. Biol. Chem. 260, 11978-11985). In order to understand the mechanism of this regulation, we have isolated and sequenced 5.4 kilobase pairs of a 12-kilobase pair human genomic clone encoding a functional GAPDH gene. The gene consists of 9 exons and 8 introns with eukaryotic signals necessary for the transcription and translation of GAPDH mRNA. The exon sequence confirms previously published cDNA sequences for human GAPDH in muscle, liver, and erythrocytes. The organization of the human and the unique chicken GAPDH genes is strikingly similar. Although chicken exons VIII-XI have been fused into human exon 8, introns which separate exons encoding the NAD binding, catalytic, and helical domains of the GAPDH protein have been retained. Stable transfection of rodent cells with the intact human GAPDH gene resulted in the expression of a correctly initiated human GAPDH mRNA and an enzymatically active human GAPDH polypeptide. Thus, the gene contains a functional promoter and intact coding sequences. Although many processed GAPDH pseudogenes and GAPDH-like sequences are present in the human genome, Southern blot analysis of human genomic DNA using a probe derived from the 3'-untranslated region of the GAPDH gene detected only two genes, a 10-copy processed pseudogene and a single copy of the isolated gene. In contrast, a probe derived from an intron segment of the isolated gene detected only a single copy of the GAPDH gene. Collectively, these findings strongly suggest that the human genome encodes a single functional GAPDH gene.

Yersinia enterocolitica enteritis in children

Five patients were admitted to Children's Hospital National Medical Center with manifestations of Yersinia enterocolitica infections. Four of five had primarily enteric illness, while the fifth had associated ocular and joint involvements. In three of five cases, the disease was self-limiting. Two of the patients (No. 1 and 2) may have had their disease improved by antibiotic therapy. Increased alertness to the potential of Y enterocolitica to cause a variety of syndromes is necessary to make an accurate bacteriologic diagnosis and to expedite medical treatment.