New stand magnifiers do not meet rated levels of performance

A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'_v) rather than equivalent dioptric power (F_m) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use.     

Pulmonary atresia with intact ventricular septum

Neonates with pulmonary atresia with intact ventricular septum are ductus dependent from birth. The initial approach in these patients is to ensure continued adequate pulmonary blood flow in anticipation of imminent spontaneous closure of the ductus. Our experience and evolving approach in the management of 16 consecutive neonates with pulmonary atresia with intact ventricular septum from 1978 to 1984 is presented. On the basis of the revised classification by Bull and associates, we divided the patients into four different groups according to right ventricular morphology. Basically, three types of palliative surgical procedures were performed: systemic-pulmonary artery shunt; systemic-pulmonary artery shunt with pulmonary valvotomy; and pulmonary valvotomy alone. Systemic-pulmonary artery shunt is the most important part of neonatal palliation. Our present routine is to perform left subclavian-main pulmonary artery shunt with a polytetrafluoroethylene tube in all patients and, in addition, to perform an open transpulmonary valvotomy without cardiopulmonary bypass in patients with a patent infundibular portion of the right ventricle. Our technique and the advantages of this type of shunt procedure are discussed. Patients with right ventricular sinusoidal-coronary artery communications are a subgroup with an additional problem. In our series, patients with this anomaly are categorized into groups with major and minor connections and their surgical significance is discussed. Overall, there was one death among 16 patients after neonatal palliative procedures and one death among five patients after hemodynamic repair.     

Early results for anatomic correction of transposition of the great arteries and for double-outlet right ventricle with subpulmonary ventricular septal defect

Fifty patients, 21 with transposition of the great arteries plus ventricular septal defect, four with double-outlet right ventricle plus ventricular septal defect, and 25 with transposition of the great arteries plus intact ventricular septum, have undergone anatomic correction. There were four hospital deaths, all in the patients with ventricular septal defects (overall mortality rate 8%). The Lecompte maneuver was used in all patients, and in the last 25 patients the coronary arteries were transposed to medially hinged trapdoor flaps created in the neoaorta. In 10 patients (20%) intraoperative adjustments were necessary to the great vessels and coronary arteries to achieve unobstructed coronary artery flow. There have been no late deaths. Postoperative cardiac catheterization in 19 patients has revealed stenosis on the new main pulmonary artery suture line to be the main early problem. Anatomic correction of transposition (with or without ventricular septal defect) and double-outlet right ventricle septal defect would seem to be a good operative alternative to the Mustard or Senning operation, with the advantage of incorporating the left ventricle into the systemic circulation.     

Cardiac conduction abnormalities and rhythm changes after neonatal anatomical correction of transposition of the great arteries.

Seventy three infants who underwent neonatal anatomical correction for transposition of the great arteries with or without a ventricular septal defect were reviewed for evidence of conduction and rhythm abnormalities on preoperative and postoperative 12 lead electrocardiograms and during 24 hour Holter monitoring. There was a partial right bundle branch block pattern in 47% (29/62) of all patients and in 60% (24/40) of those with simple transposition. Complete right bundle branch block was noted in 21% including 5% with simple transposition. Holter monitoring showed sinus rhythm in all patients except three: one had episodes of supraventricular tachycardia, another an intermittent second degree heart block, and a third a complete heart block. Atrial extrasystoles were noted in 47% (29/62) of patients but were frequent in only three patients. Occasional unifocal ventricular extrasystoles were encountered in 37% (23/62) of patients and were frequent in a further 3% (2/62). Only one patient (2%) developed multifocal ventricular extrasystoles. The frequency of important cardiac arrhythmias after neonatal anatomical correction of transposition of the great arteries was 5%, significantly less than that reported after atrial inflow diversion for the same malformation.     

Two-patch repair of complete atrioventricular septal defect in the first year of life. Results and sequential assessment of atrioventricular valve function

Before January 1987, 62 infants underwent two-patch repair of complete (51) or intermediate (11) atrioventricular septal defect at the Royal Children's Hospital, Melbourne. Median age at repair was 4.3 months and median weight was 4.4 kg. Early deaths (3%) were confined to two infants with preoperative respiratory tract infections; a further two patients died during follow-up (late mortality rate 3%). Reoperation for severe postoperative mitral regurgitation was necessary in 10 infants (16%), two of whom subsequently required mitral valve replacement with a prosthesis. Preoperative atrioventricular valve regurgitation was assessed retrospectively in 49 patients from angiography or Doppler echocardiography and was found to be absent or mild in 33 (68%), moderate in 9 (18%), and severe in 7 (14%). At the time of latest review (at a mean of 2.4 years after repair), judged from a combination of clinical and echocardiographic criteria, mitral regurgitation was absent or mild in 49 (84%) of the 58 survivors; none of them had symptomatic regurgitation or were requiring continuing medical treatment. Analysis of sequential atrioventricular valve function in 46 of the 49 patients in whom objective preoperative data were available showed no relationship between the degree of preoperative and postoperative atrioventricular valve regurgitation. Infants without Down's syndrome, however, had a significantly higher reoperation rate for severe postoperative mitral valve regurgitation (50%) than those with Down's syndrome (10%) (p = 0.007). Complete atrioventricular septal defect can be repaired in early infancy with a low mortality rate and good intermediate term results.     

Pheochromocytoma and paraganglioma: comparison of MR imaging with CT and I-131 MIBG scintigraphy

To ascertain the magnetic resonance (MR) imaging characteristics of pheochromocytomas and paragangliomas and to compare MR with computed tomography (CT) and iodine-131 metaiodobenzylguanidine (I-131 MIBG), 19 patients (18 with pheochromocytomas, one with a paraganglioma) were studied. The 18 patients with pheochromocytomas had had positive findings with I-131 MIBG scintigraphy. Abdominal pheochromocytomas were generally hypointense compared with normal liver on T1-weighted MR images and extremely hyperintense on T2-weighted MR images. MR imaging was preferable to CT in the evaluation of primary pheochromocytomas due to superior tissue characterization, particularly in the patient with hypertension and borderline catecholamine levels. For patients with recurrent or metastatic disease, the data suggest that I-131 MIBG scintigraphy is the examination of choice.     

Chaperonin-mediated assembly of wild-type and mutant subunits of human propionyl-CoA carboxylase expressed in Escherichia coli

We developed a bacterial expression system for the human alpha and beta cDNAs of propionyl-CoA carboxylase (PCC). These cDNAs (less the putative mitochondrial matrix targeting presequences) were co-expressed in Escherichia coli on one plasmid vector with each cDNA having its own IPTG-inducible promoter. Only negligible amounts of active PCC were measured despite the presence of both alpha and beta subunits as indicated by Western blot analysis and the almost complete biotinylation of the alpha subunit. Co-expression of this plasmid with a second plasmid vector over-expressing the E. coli chaperonin proteins, groES and groEL, resulted in a several hundred-fold increase in PCC specific activity, to a level comparable with that found in crude human liver extracts. PCC was partially purified on monomeric avidin affinity resin and the presence of both alpha and beta subunits was demonstrated, thereby confirming the assembly of both subunits into an active enzyme. Deficiency of either alpha PCC or beta PCC results in propionic acidemia, an autosomal recessive disorder. We used this expression system to characterize one missense mutation previously described in five Japanese alleles, namely C1283T (Thr428lle) in beta PCC. This mutation, when expressed in E.coli under the same conditions as that of wild-type PCC, had null activity, despite the presence of assembled alpha PCC and beta PCC subunits. This bacterial expression system can be useful for analysis of either alpha PCC or beta PCC mutations. Our findings indicated that the groES and groEL chaperonin proteins were essential for folding and assembly of the human PCC heteromeric subunits.