Increasing glutathione levels by a novel posttranslational mechanism inhibits neuronal hyperexcitability

Glutathione (GSH) depletion, and impaired redox homeostasis have been observed in experimental animal models and patients with epilepsy. Pleiotropic strategies that elevate GSH levels via transcriptional regulation have been shown to significantly decrease oxidative stress and seizure frequency, increase seizure threshold, and rescue certain cognitive deficits. Whether elevation of GSH per se alters neuronal hyperexcitability remains unanswered. We previously showed that thiols such as dimercaprol (DMP) elevate GSH via post-translational activation of glutamate cysteine ligase (GCL), the rate limiting GSH biosynthetic enzyme. Here, we asked if elevation of cellular GSH by DMP altered neuronal hyperexcitability in-vitro and in-vivo. Treatment of primary neuronal-glial cerebrocortical cultures with DMP elevated GSH and inhibited a voltage-gated potassium channel blocker (4-aminopyridine, 4AP) induced neuronal hyperexcitability. DMP increased GSH in wildtype (WT) zebrafish larvae and significantly attenuated convulsant pentylenetetrazol (PTZ)-induced acute 'seizure-like' swim behavior. DMP treatment increased GSH and inhibited convulsive, spontaneous 'seizure-like' swim behavior in the Dravet Syndrome (DS) zebrafish larvae (scn1Lab). Furthermore, DMP treatment significantly decreased spontaneous electrographic seizures and associated seizure parameters in scn1Lab zebrafish larvae. We investigated the role of the redox-sensitive mammalian target of rapamycin (mTOR) pathway due to the presence of several cysteine-rich proteins and their involvement in regulating neuronal excitability. Treatment of primary neuronal-glial cerebrocortical cultures with 4AP or l-buthionine-(S,R)-sulfoximine (BSO), an irreversible inhibitor of GSH biosynthesis, significantly increased mTOR complex I (mTORC1) activity which was rescued by pre-treatment with DMP. Furthermore, BSO-mediated GSH depletion oxidatively modified the tuberous sclerosis protein complex (TSC) consisting of hamartin (TSC1), tuberin (TSC2), and TBC1 domain family member 7 (TBC1D7) which are critical negative regulators of mTORC1. In summary, our results suggest that DMP-mediated GSH elevation by a novel post-translational mechanism can inhibit neuronal hyperexcitability both in-vitro and in-vivo and a plausible link is the redox sensitive mTORC1 pathway.

Neuron-specific mitochondrial oxidative stress results in epilepsy, glucose dysregulation and a striking astrocyte response

Mitochondrial superoxide (O₂^-) production is implicated in aging, neurodegenerative disease, and most recently epilepsy. Yet the specific contribution of neuronal O₂^- to these phenomena is unclear. Here, we selectively deleted superoxide dismutase-2 (SOD2) in neuronal basic helix-loop-helix transcription factor (NEX)-expressing cells restricting deletion to a subset of excitatory principle neurons primarily in the forebrain (cortex and hippocampus). This resulted in nSOD2 KO mice that lived into adulthood (2-3 months) with epilepsy, selective loss of neurons, metabolic rewiring and a marked mitohormetic gene response. Surprisingly, expression of an astrocytic gene, glial fibrillary acidic protein (GFAP) was significantly increased relative to WT. Further studies in rat primary neuron-glial cultures showed that increased mitochondrial O₂^-, specifically in neurons, was sufficient to upregulate GFAP. These results suggest that neuron-specific mitochondrial O₂^- is sufficient to drive a complex and catastrophic epileptic phenotype and highlights the ability of SOD2 to act in a cell-nonautonomous manner to influence an astrocytic response.

Drosophila R8 photoreceptor cell subtype specification requires hibris

Cell differentiation and cell fate determination in sensory systems are essential for stimulus discrimination and coding of environmental stimuli. Color vision is based on the differential color sensitivity of retinal photoreceptors, however the developmental programs that control photoreceptor cell differentiation and specify color sensitivity are poorly understood. In Drosophila melanogaster, there is evidence that the color sensitivity of different photoreceptors in the compound eye is regulated by inductive signals between cells, but the exact nature of these signals and how they are propagated remains unknown. We conducted a genetic screen to identify additional regulators of this process and identified a novel mutation in the hibris gene, which encodes an irre cell recognition module protein (IRM). These immunoglobulin super family cell adhesion molecules include human KIRREL and nephrin (NPHS1). hibris is expressed dynamically in the developing Drosophila melanogaster eye and loss-of-function mutations give rise to a diverse range of mutant phenotypes including disruption of the specification of R8 photoreceptor cell diversity. We demonstrate that hibris is required within the retina, and that hibris over-expression is sufficient to disrupt normal photoreceptor cell patterning. These findings suggest an additional layer of complexity in the signaling process that produces paired expression of opsin genes in adjacent R7 and R8 photoreceptor cells.

Mitochondrial aconitase knockdown attenuates paraquat-induced dopaminergic cell death via decreased cellular metabolism and release of iron and H₂O₂

Mitochondrial oxidative stress is a contributing factor in the etiology of numerous neuronal disorders. However, the precise mechanism(s) by which mitochondrial reactive oxygen species modify cellular targets to induce neurotoxicity remains unknown. In this study, we determined the role of mitochondrial aconitase (m-aconitase) in neurotoxicity by decreasing its expression. Incubation of the rat dopaminergic cell line, N27, with paraquat (PQ(2+) ) resulted in aconitase inactivation, increased hydrogen peroxide (H(2) O(2) ) and increased ferrous iron (Fe(2+) ) at times preceding cell death. To confirm the role of m-aconitase in dopaminergic cell death, we knocked down m-aconitase expression via RNA interference. Incubation of m-aconitase knockdown N27 cells with PQ(2+) resulted in decreased H(2) O(2) production, Fe(2+) accumulation, and cell death compared with cells expressing basal levels of m-aconitase. To determine the metabolic role of m-aconitase in mediating neuroprotection, we conducted a complete bioenergetic profile. m-Aconitase knockdown N27 cells showed a global decrease in metabolism (glycolysis and oxygen consumption rates) which blocked PQ(2+) -induced H(+) leak and respiratory capacity deficiency. These findings suggest that dopaminergic cells are protected from death by decreasing release of H(2) O(2) and Fe(2+) in addition to decreased cellular metabolism.

Fluorogenic Hand‐Held Immunoassay for the Identification of Ricin: Rapid Analyte Measurement Platform

Rapid analyte measurement platform (RAMPtrade mark) fluorogenic hand-held immunoassays (HHAs) were evaluated for inclusivity/sensitivity, exclusivity/specificity, sample matrix effects, ruggedness/stability, and reproducibility in detection of ricin (RCA(60)), a potential biological threat agent. The limit of detection of HHAs for RCA(60) was 14 ng/mL or approximately 140 pg/test. HHAs were inclusive in detection of ricin RCA(60), RCA(120), ricin A chain, and ricin B chain and exclusive in discrimination of RCA(60) from other toxins. None of the sample matrices tested affected assay performance. RAMPtrade mark ratios were tolerant of increases in sample volume, however, a decrease in sample volume of 25% resulted in significantly increased readings. RAMPtrade mark readings were highly reproducible lot-to-lot, cartridge-to-cartridge, day-to-day, and reader-to-reader.

Development of a biotin mimic tagged ScFv antibody against western equine encephalitis virus: bacterial expression and refolding

Single chain antibodies (ScFvs) are heavy and light chain variable domains connected by an artificial linker. Because of their smaller size, ScFvs show improved tissue penetration in vivo and reduced immunogenicity, making them ideal for therapeutic applications. We have cloned a ScFv against western equine encephalitis (WEE) using rDNA technology. The ScFv was generated from a hybridoma cell line (11D2) specific to the WEE virus E1 glycoprotein and is arranged in the V(L)-V(H) orientation with a (gly(4)ser)(3) linker. This ScFv was engineered successfully with a biotin mimic tag (11 amino acid peptide) and cloned in the pET22b+ expression vector. The ScFv was expressed as a approximately 32kDa protein in Escherichia coli as inclusion bodies, with an estimated yield of 20-40 mg/l. Different refolding protocols were used to solubilise the inclusion bodies. Most of the functional ScFv was generated when the inclusion bodies were solubilized in a detergent, air oxidised in the presence of CuSO(4) and then denatured in urea buffer in comparison to other protocols. The product was renatured finally in Tris arginine buffer (pH 8.0). Refolded protein was dialysed against phosphate buffer saline (PBS) (pH 7.3) to remove the Tris and arginine. Our refolding protocol generated up to a 50% yield of soluble protein, which retained antigen-binding activity with whole inactivated WEE virus as demonstrated by ELISA and Western blot analysis. This 11D2-biotin mimic ScFv complexed with streptavidin horseradish peroxidase (St-HRPO) will be useful as a detector reagent in the ultrasensitive ELISA detection of WEE virus antigen.

Development of a second generation monoclonal single chain variable fragment antibody against Venezuelan equine encephalitis virus: expression and functional analysis

We have generated a single chain variable fragment (ScFv) antibody from a well-characterized monoclonal antibody (MAb) against Venezuelan equine encephalitis virus (VEE), by cloning variable regions of the heavy (V(H)) and the light (V(L)) chain antibody genes, connected by a DNA linker, in phagemid expression vector pCANTAB 5 E. MAb 1A4A1 was successfully cloned as a ScFv in Escherichia coli strain TG-1 and expressed as a approximately 30 kDa ScFv protein which was functional in recognizing VEE by ELISA. Results were reproduced in Escherichia coli strain HB2151 where the same clone, designated A116, was expressed primarily as soluble periplasmic protein. The 30 kDa A116 antibody displayed weak binding specificity to VEE antigen. Sequence analysis revealed a frame shift in the N-terminal region of the V(L) domain, upstream to the complementarity-determining region 1 (CDR1), as the probable cause of reduced activity. The protein sequence of A116 was highly homologous to published murine ScFv protein sequences except in the region of the identified frame shift.

Bispecific and bifunctional single chain recombinant antibodies

Bispecific and bifunctional monoclonal antibodies as second generation monoclonals, produced by conventional chemical or somatic methods, have proved useful in the immunodiagnosis and immunotherapy of cancer and other diseases. Recombinant antibodies produced by genetic engineering techniques have also become available for use in preclinical and clinical studies. Furthermore, through genetic engineering, it is possible to remove or add on key protein domains in order to create designer antibody molecules with two or more desired functions. This review summarizes the strategies for development of single chain variable fragment (scFv) bifunctional and bispecific antibodies. The advantages and disadvantages as well as the problems of generating the various bispecific and bifunctional antibody constructs are reported and discussed. Since conventionally prepared bispecific and bifunctional monoclonal antibodies have already shown promise in clinical trials and results from preclinical studies of recombinant bispecific antibodies are encouraging, clinical trials in humans of recombinant bispecific and bifunctional antibodies, as a new generation of biologicals, are likely to be the thrust in the next decade and beyond.

SSCP analysis of cDNA markers provides a dense linkage map of the Aedes aegypti genome

An intensive linkage map of the yellow fever mosquito, Aedes aegypti, was constructed using single-strand conformation polymorphism (SSCP) analysis of cDNA markers to identify single nucleotide polymorphisms (SNPs). A total of 94 A. aegypti cDNAs were downloaded from GenBank and primers were designed to amplify fragments <500 bp in size. These primer pairs amplified 94 loci, 57 (61%) of which segregated in a single F(1) intercross family among 83 F(2) progeny. This allowed us to produce a dense linkage map of one marker every 2 cM distributed over a total length of 134 cM. Many A. aegypti cDNAs were highly similar to genes in the Drosophila melanogaster genome project. Comparative linkage analysis revealed areas of synteny between the two species. SNP polymorphisms are abundant in A. aegypti genes and should prove useful in both population genetics and mapping studies.

Microsatellite loci are not abundant in all arthropod genomes: analyses in the hard tick, Ixodes scapularis and the yellow fever mosquito, Aedes aegypti

Plasmid libraries enriched for microsatellites were generated in the tick, Ixodes scapularis and in the mosquito Aedes aegypti. Libraries were enriched for genomic DNA containing (AC)n, (AG)n, (ATG)n, (CAG)n, (TAG)n, (AAT)n, (CTGY)n or (GATA)n motifs. Clones containing each motif were sequenced in both species for PCR primer design. In I. scapularis, most primers amplified a single locus and alleles varied in the number of microsatellite repeats and segregated as codominant markers. In contrast (AC)n, (TAG)n and (GATA)n microsatellite loci extracted from Ae. aegypti appeared to be members of multigene families. A primer pair designed to amplify a particular TAG locus instead amplified many independently segregating loci, some of which did not contain TAG microsatellites. Alleles at the TAG loci segregated as dominant markers and there was limited evidence for length variation among alleles. These results suggest that microsatellite loci are not universally abundant in arthropod genomes nor do alleles always segregate as codominant markers.

Quantitative trait loci that control vector competence for dengue-2 virus in the mosquito Aedes aegypti

Quantitative trait loci (QTL) affecting the ability of the mosquito Aedes aegypti to become infected with dengue-2 virus were mapped in an F(1) intercross. Dengue-susceptible A. aegypti aegypti were crossed with dengue refractory A. aegypti formosus. F(2) offspring were analyzed for midgut infection and escape barriers. In P(1) and F(1) parents and in 207 F(2) individuals, regions of 14 cDNA loci were analyzed with single-strand conformation polymorphism analysis to identify and orient linkage groups with respect to chromosomes I-III. Genotypes were also scored at 57 RAPD-SSCP loci, 5 (TAG)(n) microsatellite loci, and 6 sequence-tagged RAPD loci. Dengue infection phenotypes were scored in 86 F(2) females. Two QTL for a midgut infection barrier were detected with standard and composite interval mapping on chromosomes II and III that accounted for approximately 30% of the phenotypic variance (sigma(2)(p)) in dengue infection and these accounted for 44 and 56%, respectively, of the overall genetic variance (sigma(2)(g)). QTL of minor effect were detected on chromosomes I and III, but these were not detected with composite interval mapping. Evidence for a QTL for midgut escape barrier was detected with standard interval mapping but not with composite interval mapping on chromosome III.

Construction and characterization of monoclonal antibodies against western equine encephalitis virus

A repertoire of mouse monoclonal antibodies (MAbs) against western equine encephalitis virus (WEE) was constructed and characterized. Anti-WEE antibodies were expressed from hybridomas and purified by protein G chromatography. Each of the antibodies was functionally assessed by indirect enzyme-linked immunosorbent assays (ELISAs), Western blotting, and immunoprecipitations. All antibodies bound to WEE antigen in ELISAs, whereas only a subgroup of antibodies was found to be active in Western blotting and immunoprecipitations. A subset of antibodies was found to cross-react with other alphaviruses, such as Sindbis virus (SIN), Venezuelan equine encephalitis (VEE), and eastern equine encephalitis (EEE). Because many of the antibodies were highly reactive to WEE antigen in one or more of the assays, these antibodies are excellent candidates for immunodetection and immunotherapy studies.

Development of a functional monoclonal single-chain variable fragment antibody against Venezuelan equine encephalitis virus

We have generated a single-chain variable fragment (ScFv) antibody, from a previously well-characterized monoclonal antibody (MAb) to Venezuelan equine encephalitis (VEE) virus, 5B4D-6. The variable regions of the heavy (V(H)) and light (V(L)) chain antibody genes, were connected by a DNA linker and cloned in the phagemid vector pCANTAB5E. The ScFv clone in Escherichia coli strain TG-1, 5B4D-6-6, was expressed as a approximately 30 kDa ScFv protein and higher molecular weight fusion products which were functional in recognizing VEE virus by enzyme-linked immunosorbent assay (ELISA). Results were reproduced in Escherichia coli strain HB2151, where clone D66 was expressed mainly as soluble periplasmic protein. The D66 ScFv antibody bound VEE virus strongly as determined by ELISA. Nucleotide sequence analysis of 5B4D-6-6 ScFv indicated that the Vkappa gene belonged to family XVI, subgroup V, while the V(H) gene was unique in its sequence, though its amino acid sequence could be subgrouped as IA. The deduced protein sequence of D66 was highly homologous to published murine ScFv protein sequences. This work demonstrates, for the first time, cloning of a functional ScFv antibody against VEE virus.

A single chain Fv specific against Western equine encephalitis virus

A recombinant single chain Fv (scFv) specific against Western equine encephalitis virus (WEE) was developed and characterized. The scFv was generated from 11D2 hybridoma producing anti-WEE antibody reactive to E1 component of viral envelope glycoprotein. V(L) and V(H) gene segments of 11D2 scFv were generated and joined together with a (gly4ser)3 linker by polymerase chain reaction (PCR). The resulting scFv was successfully expressed in P. pastoris expression system. Fifteen individual plasmids were tested and six of them were shown to drive scFv expression. DNA sequence analysis from three productive plasmids showed that they all carried the same VL and V(H) gene segments with a few base differences. Comparison of 11D2 scFv DNA sequence to the Kabat database showed that VH of 11D2 antibody belonged to subgroup IIID and subfamily XIV, while VL domain did not belong to any known subgroup or subfamily. Western blot analysis of 11D2 scFv using anti-c-myc antibody for detection showed different band pattern among clones derived from different plasmids. This was thought to be due to the different glycosylation where amino acid substitution occurred. Successful purification of 11D2 scFv could be done by immobilized metal affinity chromatography with an unoptimized yield of 700 microg/L. Functional studies showed that 11D2 scFv could bind to its respective WEE antigen as demonstrated by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). The binding affinity of 11D2 scFv is reasonably good compared to the parental 11D2 bivalent monoclonal antibody (MAb). Thus, 11D2 scFv and its derivatives have a potential use as immunotherapeutic and immunodiagnostic agents of WEE infections.

Rapid immunofiltration assay of Newcastle disease virus using a silicon sensor

A rapid nonradioactive sandwich immunoassay which utilizes biotin-streptavidin mediated filtration capture of immune complexes in conjunction with a silicon sensor was developed for the detection of virus. Using purified Newcastle disease virus as a model, the lower limits of detection (LOD) were determined for a number of immunoassay configurations employing both monoclonal and polyclonal antibodies. The LODs ranged from 1.3 ng/ml (sample volume of 100 microliter) for an incubation of 60 min to 400 ng/ml for a 1 min incubation. The sandwich immune complexes were formed from one-step incubation of antibody and antigen. No 'hook' effects were observed over a wide range of analyte concentrations. The assays were easy to perform and required a total time equal to the incubation period plus about 5 min. The assay format is suitable for virus, bacteria and protein antigens. New assays can be developed and optimized readily, often within 1 day.

Epitope specificity of monoclonal antibodies against Newcastle disease virus: competitive fluorogenic enzyme immunoassay

A test to determine the epitope specificity of monoclonal antibodies (MCA) was developed for hybridoma clones producing antibodies against Newcastle disease virus (NDV). The virus was first immobilized on nitrocellulose membranes of Millititer HA plates. Dilutions of MCA were then added, singly, or simultaneously in pairs, and bound antibody was quantitated with alkaline phosphatase-labelled detector antibody and a fluorogenic substrate, 4-methylumbelliferyl phosphate (4-MUP). Fluorescence count was measured fluorometrically. Additivity indices were calculated and plotted against dilutions of paired MCA. Antibodies that recognized identical epitopes displayed non-additivity at saturating antibody dilutions, followed by partial additivity and by total additivity at low, non-saturating dilutions. In contrast, MCA that recognized distinct epitopes exhibited total additivity throughout the curve. MCA that exhibited partial additivity were interpreted as competing for overlapping shared epitopes, or, distinct epitopes in close proximity, resulting in steric hinderance.

Sensitive avidin-biotin amplified fluorogenic enzyme immunoassay using biotinylated monoclonal antibodies for the identification and quantitation of virus

A highly sensitive amplified fluorogenic enzyme-linked immunosorbent assay (FELISA), which utilizes the high affinity interaction of the vitamin biotin for the multiple binding sites on the glycoprotein avidin, was developed for the detection and identification of a model virus, Newcastle disease virus (NDV). Monoclonal antibodies (MCA) directed against the virus were purified and labelled with biotin. Biotinylated MCA was then used with avidin-labelled enzyme and a fluorogenic substrate to detect NDV adsorbed directly on nitrocellulose membranes. Reagents were standardized and, using purified virus, the theoretical lower limit of test sensitivity of the amplified FELISA was determined to be 1 fg/ml of test sample (50 ag/well). The specificity of the amplified FELISA was evaluated by challenging the assay system with homologous and heterologous strains of NDV, and with other serologically related and unrelated viruses. The test was simple to perform and multiple samples could be conveniently assayed with results obtainable in 3-4 h.

Sensitive fluorogenic enzyme immunoassay on nitrocellulose membranes for quantitation of virus

A highly sensitive fluorogenic enzyme-linked immunosorbent assay (FELISA), which utilizes nitrocellulose membranes as solid phase support, has been developed for the detection and identification of virus in clinical samples. Reagents were standardized and, using purified Newcastle disease virus (NDV) as a model, the theoretical lower limits of test sensitivity of the FELISA were compared, in both "sandwich" and "indirect" formats, to those of a comparable chromogenic enzyme-linked immunosorbent assay (CELISA). Of the systems evaluated, the "sandwich" FELISA exhibited maximum sensitivity and detected 10 fg of purified virus protein per milliliter of test sample (500 ag per test volume). Specificity of the "sandwich" FELISA was evaluated by challenging the system with heterologous strains of NDV and with other serologically related and unrelated viruses. In a clinical trial in which fecal materials from chickens undergoing vaccination with NDV were assayed directly by FELISA, the virus was detected from the first to approximately the tenth day post-vaccination. The test is simple to perform and results can be obtained in approximately 4 h.

Rapid rate-kinetic turbidometric assay for quantitation of viral complement-fixing antibodies

A rapid rate-kinetic turbidometric assay for the quantitation of viral complement fixing antibodies has been developed, using adenovirus as a model. The procedure is based on the turbidometric quantitation of intact sheep erythrocytes and measures the rate of hemolysis (change in absorbance at 640 nm/min/), at maximum velocity, occurring in the presence of residual complement not fixed by the antigen-antibody reaction. Reagents were standardized and assays performed using a microprocessor-controlled spectrophotometer with kinetic assay capability and a thermoregulated cell compartment. Eleven sera were assayed for complement fixing antibodies both by the conventional microtiter technique and by the rapid turbidometric method described here. Good correlation (r = 0.89) was obtained between the two procedures. Unlike the conventional complement fixation test, the rate-kinetic turbidometric complement fixation assay was found to be tolerant of variation in complement and antigen concentration, endpoint titers were objectively quantitated and, once reagents had been standardized, results could be obtained within 45-60 min. The technique is potentially adaptable to large-scale automation.

Single radial hemolysis test for quantitation of complement-fixing antibodies to non-hemagglutinating viruses

A single radial hemolysis test, which overcomes many of the problems of conventional complement fixation tests, was developed for the quantitation of virus complement-fixing antibodies. The test procedure utilized staphylococcal protein A-coated sheep erythrocytes immobilized in agarose into which antigen was incorporated. Undiluted heat-inactivated serum samples were allowed to diffuse radially from wells punched in the agarose. Protein A served to concentrate the subsequent antigen-antibody reaction on the surface of the erythrocytes. Zones of hemolysis were developed by flooding with complement. With adenovirus as a model, basic test parameters were defined, and optimum reagent concentrations and diffusion conditions were determined. A positive linear relationship was found to exist between zone diameter and increasing log concentration of specific antiserum. No correlation was found between zone diameter and total concentration of immunoglobulin G in test sera. Sera rendered anticomplementary by the addition of carrageenan produced hemolytic zones equal to diameter to those observed with untreated sera. Seventy-seven human sera with known complement fixation titers were tested by this method. Good correlation (r = 0.74) between the complement fixation test and single radial hemolysis was observed. This test was highly reproducible and more sensitive than the conventional complement fixation test.

Coronary artery disease in diabetic and nondiabetic patients: a clinical and angiographic comparison

A comparison of data from 58 diabetic and 58 nondiabetic patients with arteriographic evidence of coronary artery disease showed that diabetic patients had a significantly greater frequency of major stenoses in the intermediate coronary artery segments but no significant differences in the proximal or distal segments. Thus, the diabetic patients did have more severe coronary disease, but the diabetic group did not have "more distal" disease as represented by the number of major or minor lesions in the distal segments. The diabetic patients had a significantly greater frequency of electrocardiographic intraventricular conduction defects and manifestations of left ventricular dysfunction. There was no significant difference in the severity of coronary artery disease between the diabetic patients with manifestations of myocardial decompensation and the diabetic patients without such manifestations, suggesting that the increased frequency of myocardial dysfunction in diabetic patients may be related to factors other than the greater severity of coronary artery disease.

Isolation of a subclavian artery

Eight patients with isolation of a subclavian artery are described. Isolation of subclavian artery is defined as a loss of continuity between the subclavian artery and aorta but with persistent connection to the homolateral pulmonary artery through a ductus arteriosus. The connecting ductus arteriosus may or may not be patent. As the pulmonary vascular resistance is usually lower than the systemic resistance, the isolated subclavian artery is perfused by subclavian steal, and if the connecting ductus arteriosus is patent, flow occurs from the subclavian artery into the pulmonary artery. In this material and in all reported cases, isolation of subclavian artery has always been associated with other anomalies of the aortic arch, such as right aortic arch or bilateral ductus. Its frequent association with intracardiac defects, usually the tetralogy of Fallot, makes its recognition clinically important. Thoracic aortography with delayed filming is the only procedure that allows consistent diagnosis of this rare anomaly during life.

The unpredictable progression of symptomatic coronary artery disease: a serial clinical-angiographic analysis

To determine whether risk factors or angiographic features could be correlated with progression of coronary artery disease, we independently analyzed serial coronary angiograms in 65 symptomatic patients for progression without knowledge of their respective risk factors. An important design feature of this study was that observer variability of coronary lesion assessment was objectively evaluated and taken into account in defining progression of coronary artery disease. The reproducibility of lesion assessment varied with the severity of stenosis: moderate stenoses had the greatest intraobserver and interobserver variability. At initial study, 337 partial and 68 complete occlusions were identified. Of the 337 partial occlusions at risk of progression, 73 (22%) progressed; 13 (3.2%) of the initial lesions regressed. In the 65 patients with persistent or increasing angina, progression occurred in 51 (78%) over a mean period of 24 months. Apart from the tendency of high-grade stenosis( greater than or equal to 98%) to progress to complete occlusion, no measured clinical, laboratory, or angiographic variable showed any significant effect on progression to coronary artery disease, in this selected group of symptomatic patients these same risk factors did not predict its progression. We believe that (1) and definition of progression should incorporate the factor of observer variability and (2) therapeutic measures designed to influence progression of coronary artery disease should take into account this apparently unpredictable progression.

Right and left ventricular function after the Mustard procedure in transposition of the great arteries

Right and left ventricular function was assessed at cardiac catheterization in 33 asymptomatic patients 0.5 to 11 years (mean 4.6) after the Mustard operation for complete transposition of the great arteries. Ages at operation had ranged from 0.5 to 16 years (mean 4.2 years). Right ventricular function was assessed using videodensitometric determination of ejection fraction and ventricular volume data. Ventricular volumes were obtained by computerized video analysis utilizing Simpson's rule. The right ventricular ejection fraction was 37 +/- 11 percent (standard deviation), as assessed with videodensitometry and 42 +/- 10 percent as assessed with ventricular volume--both values less than normal (P less than 0.001). Right ventricular end-diastolic volume was significantly greater than normal (P less than 0.001) and averaged 202 +/- 70 percent, but left ventricular end-diastolic volume averaged only 125 +/- 53 percent. These observations after the Mustard operation indicate that right ventricular function is seriously decreased with relatively preserved left ventricular function. They support efforts for surgical correction utilizing the left ventricle as the systemic ventricle.

Anomalous origin of left coronary artery from pulmonary artery in association with intracardiac lesions. Report of two cases

Two cases are presented to illustrate the diagnostic and therapeutic dilemma when an anomalous origin of the left coronary artery from the pulmonary artery occurs with a hemodynamically significant intracardiac lesion. Hemodynamic alterations resulting from the associated intracardiac lesion may obscure the clinical features of the coronary arterial abnormality, and the appearance of normal coronary arterial distribution with left ventricular or aortic root angiography may create a false impression of a normal origin of the coronary arterial supply. A high index of suspicion may be the only lead to the detection of an anomalous origin of the left coronary artery from the pulmonary artery in association with an intracardiac lesion. In addition to the intracardiac lesion known to be associated with coronary arterial abnormalities, the question of anomalous coronary supply should be raised by the finding of poor left ventricular function or mitral insufficiency after operation (unexplainable by other causes), by the development of poor myocardial function during cardiac catheterization or anesthesia, or by the significant enlargement of a coronary artery seen during left ventriculography or supravalvular aortography.

Surgical repair of criss-cross heart with straddling atrioventricular valve

The criss-cross heart is a rare anomaly in which systemic and pulmonary bloodstreams cross at the atrioventricular (AV) level. Although diagnosed now with increasing frequency, successful surgical repair of associated anomalies has been reported only once. Straddling AV valve is another rare cardiac anomaly which only recently is being diagnosed consistently preoperatively and corrected surgically. This is the first report of successful repair of cardiac anomalies in a patient with the combination of straddling AV valve and criss-cross AV relationships. The uneventful postoperative course and good result on follow-up in this patient are gratifying and suggest that this combination of anomalies now can be repaired with results as good as those for less complex forms of congenital heart disease.

Use of the Simmons "Sidewinder" femoral-cerebral catheter for abdominal angiography

The authors describe a single catheter system which allows rapid, routine abdominal angiography. Selective and subselective studies are easily performed, and the catheter can be used without modification for Pitressin infusion and embolization.

Caplike double-horned double-outlet right ventricle. Report of two cases

Two patients with a rare form of double-chambered, double-outlet right ventricle (DORV) are described. Both patients had associated pulmonary stenosis, ventricular septal defect, and a large tricuspid valve whose chordal attachments crossed the right ventricular outflow tract. The angiocardiographic, echocardiographic, and operative findings were distinctive. The right ventricle was positioned as a "cap" sitting atop the ventricular septal defect at the cephalad end of the left ventricle. The right ventricle, with its two "horns," was likened to a rider straddling a saddle. Tricuspid chordal attachments extended into each of the two right ventricular "horn." No repair was performed in the asymptomatic patient. The other repair involved closure of the tricuspid orifice and insertion of a valved extracardiac conduit from the right atrium to the pulmonary artery.

Congenital pulmonary atresia: photographic subtraction as an aid in recognizing hypoplastic pulmonary arteries

Photographic subtraction is a valuable adjunct for studying patients with pulmonary atresia, ventricular septal defect, and systemic pulmonary collateral vessels. In about 9% of 282 patients, it helped identify the true central pulmonary arteries and whether or not they were confluent. This technique, used retrospectively in evaluating patients previously considered inoperable, has permitted recall of several patients for repeat study and probable corrective or palliative surgery.

Great-vessel switch operation without coronary relocation for transposition of great arteries

Since its first successful clinical application in 1963, the Mustard operation has been the procedure of choice for most patients with transposition of the great arteries. Based on the principle of transposition of venous return, it produces a functional but not anatomic correction of the defect. Although the Mustard procedure has favorably changed the natural history of transposition, it is associated with various early and late complications that have led to a search for a more anatomic repair. Recently, transposition has been successfully corrected by switching the great vessels, with or without transplanting the coronary arteries. These are the first case reports of early postoperative hemodynamics in patients undergoing an arterial switch procedure without coronary relocation. The early hemodynamic and clinical results of this operation are excellent and they lend encouragement for its further application in suitable patients.

Congenital pulmonary atresia with ventricular septal defect: angiographic and surgical correlates

Of 181 patients with severe congenital pulmonary atresia and ventricular septal defect or "type IV truncus" (an obsolete term), all but 11% had true central pulmonary arteries. These arteries were demonstrable by large serial biplane angiograms using multiple selective injections into collateral vessels, frequent photographic subtraction, and occasional pulmonary vein-wedge angiograms. These techniques are extremely important for accurate diagnosis and in planning corrective or palliative surgery, which was done in 77% of patients with pulmonary arteries.

Thrombotic occlusion of Hancock conduit due to severe dehydration after Fontan operation

Six months after undergoing a Fontan procedure for tricuspid valve atresia, a 7-year-old child experienced thrombotic occlusion of the Hancock conduit coincident with an acute gastroenterologic illness that produced sudden, severe dehydration. Recovery from this complication was possible only by virtue of pulmonary blood flow through a Glenn anastomosis, which had been constructed at 1 year of age and which was left in place at the time of the Fontan procedure. At subsequent reoperation, the Hancock conduit, which was completely occluded with organized thrombus, was replaced with another Hancock conduit, and the patient is now doing well 10 months after this last operation. The relatively nonpulsatile flow characteristic of blood passing through the prosthetic conduit after the Fontan operation predisposes the patient to the possibility of the potentially lethal complication, previously unreported, of thrombotic occlusion of the conduit, and care must be taken to avoid severe dehydration in such patients.

Regional myocardial wall thickening response to nitroglycerin. A predictor of myocardial response to aortocoronary bypass surgery

The peak rate of systolic wall thickening (p +/- dTw/dt) in regions of the left ventricle (LV) was determined preoperatively by biplane roentgen videometry in 18 patients before and after sublingual administration of nitroglycerin (NTG) and 3-23 months (median 12) after aortocoronary bypass surgery. The regional LV response to NTG was a reliable predictor for postoperative improvement in regional wall dynamics after successful aortocoronary bypass grafting. The ejection fraction response to NTG or surgery will not predict the regional myocardial response to NTG or surgery, nor will the regional response predict the global response. Subendocardial myocardial infarction is another cause of unimproved regional myocardial function after NTG and aortocoronary bypass surgery.

Misdiagnosis of atrial septal defect in patients with hereditary telangiectasia (Osler-Weber-Rendu disease) and hepatic arteriovenous fistulas

Two patients with hereditary telangiectasia (Osler-Weber-Rendu disease) and high-output congestive heart failure secondary to large hepatic arteriovenous malformations had preoperative heart catheterization and exploratory cardiotomy to correct presumed intracardiac left-to-right shunts at the atrial level. At operation, both patients had oxygen-enriched blood returning from the inferior vena cava. Subsequent hepatic angiography demonstrated large hepatic arteriovenous fistulas, and both patients underwent hepatic artery banding and ligation, with reduction of left-to-right shunting.

False aneurysm of the descending aorta: a complication of umbilical artery catheterization

A patient had an aneurysm of the descending aorta secondary to aortitis arising from umbilical artery catheterization and in association with coarctation of the aorta. The aortitis probably was the direct result of bacterial contamination of the umbillicus and catheter with Staphylococcus aureus and the placement of the catheter tip just distal to a coarctation of the aorta. The patient required surgical resection of the coarctation and aneurysm of the descending aorta and placement of a tubular Dacron graft at 6 month of age. This is, to our knowledge, a hitherto unreported complication of umbilical artery catheterization.

Systemic collateral and pulmonary artery stenosis in patients with congenital pulmonary valve atresia and ventricular septal defect

Angiograms of 30 patients with congenital pulmonary valve atresia, ventricular septal defect, and large systemic-pulmonary collateral arteries (SPCAs) were evaluated. All had aortography, 28 had SPCA arteriography, and 26 had right ventriculography. Seventeen (65%) of 26 patients had a right ventricular infundibulum, 23 (77%) had a pulmonary artery confluence, and five of the nine patients without a right ventricular infundibulum had a confluence. Sixty-six SPCAs of aortic origin were seen; 28 (42%) had narrowing and 21 patients (70%) had one or more narrowed SPCAs. Five patients had collaterals from internal mammary, subclavian or innominate arteries. Fourteen (47%) had hilar pulmonary artery stenosis. Of these 14 patients mild peripheral stenosis was demonstrated in five. Right aortic arch was present in 15 patients (50%). Complete angiographic delineation of pulmonary vasculature is an essential procedure for preoperative detection of pulmonary and SPCA stenoses in these patients.

The ileal stoma and protal hypertension: an uncommon site of variceal bleeding

Patients who have chronic ulcerative colitis coexisting with liver disease and portal hypertension may suffer hemorrhagic parastomal varices after proctocolectomy and ileostomy. Large portal systemic collateral vessels between the superior mesenteric venous tributaries and the abdominal wall can be demonstrated by portal venography. Hemorrhage occurs from the mucocutaneous junction, a vulnerable point in this collateral circuit. Management by major and minor stomal revisions has been unsuccessful. Three patients who have bled from stomal and from esophagogastric varices were treated with portasystemic shunts. None of the three has had recurrent bleeding or postshunt encephalopathy during the 19 to 27 months after these operations.

Renal vein thrombosis

The manifestations, clinical course and treatment of 14 patients with non-malignant renal vein thrombosis are described. Most patients (10 of 14) had generalized vague illness and nephrotic syndrome but 4 were initially seen with acute symptoms of flank pain, hematuria or hypertension. Renal vein thrombosis affected young men 2.5 times more often than women and occurred on the left side 2.6 times more commonly than on the right or both sides. Red blood cell casts in the urinary sediment, heavy proteinuria and hypoalbuminemia were useful indicators of the disease. Excretory urographic signs were suggestive of renal vein thrombosis in all patients and these were corroborated by angiographic studies. Systemic anticoagulation with or without a renal failure program and diuretics, or simply a combination of the last 2 modalities, was used in 9 patients. In 2 of the 9 patients who were unresponsive the adjuvant use of cyclophosphamide and steroids effected a cure. The remaining 5 patients underwent nephrectomy or thrombectomy. All 14 patients were followed for 1 to 7 years (mean 1.6 years). Ten patients were cured or improved, 1 patient was unchanged, and in the remaining 3 patients the condition deteriorated and they subsequently required a renal allograft. The rationale for various forms of treatment is discussed.

Aortic homograft obstruction

At the Mayo Clinic from September 1967, to November 1972, 128 patients underwent operations in which an aortic homograft was used to establish right ventricle-to-pulmonary artery continuity. Recently, we studied 18 of these patients who had calcified, obstructed aortic homografts. Seven patients had histories of significant dysrhythmias, all of which required medication and two of which were life threatening. Seventeen of the patients had systemic or suprasystemic pressure in the right ventricle before replacement of the calcified homografts. After placement of the homograft with a Hancock prosthesis, the pressure in the right ventricle of 12 patients was one half the systemic pressure or less. There were no operative deaths, and only 2 patients developed any significant postoperative problems.

Successful surgical repair of aortico-left ventricular tunnel in an infant

Aortico-left ventricular tunnel is a rare congenital malformation in which a perivalvular tunnel produces free communication between the aortic root and left ventricle. The hemodynamic consequences of this lesion are similar to those of aortic valve incompetence. Infants with this condition have clinical findings that should suggest it as a diagnostic possibility, and aortic root angiocardiography can establish the diagnosis. Early severe congestive heart failure is common in infants with this malformation, and in such patients prompt surgical correction of the deformity is recommended. This paper reports surgical correction of aortico-left ventricular tunnel in a 9-month-old child, the first reported patient to be successfully operated on before age 2 years.

Immunofluorescence in diagnosis of measles infections in children

Nasopharyngeal cells of 24 patients diagnosed as being in the prodromal phase or with established measles were examined by indirect immunofluorescence microscopy for the presence of measles antigen. Eighteen patients were positive for measles antigen by this technique. In ten of the 18 patients it was necessary to remove masking globulins from the antigen-containing cells prior to staining. Results obtained by immunofluorescence were supported by cytologic and serologic findings. No virus isolations were achieved. Immunofluorescence microscopy with elution of adherent globulins offers the most rapid and sensitive method for the laboratory diagnosis of measles.