Clinical Outcomes of Conservative Treatment for Low-Risk Ductal Carcinoma in Situ: A Systematic Review and Pooled Analysis

AIMS

The current gold standard of treatment for ductal carcinoma in situ (DCIS) is surgical resection with or without adjuvant radiotherapy. However, the increased detection and radical treatment of DCIS did not result in a declined incidence of invasive breast cancers, leading to the debate if DCIS has been overtreated. While ongoing randomised controlled trials on active surveillance of DCIS are still in progress, this systematic review aims to evaluate the best evidence on conservative treatment for DCIS from the literature.

MATERIALS AND METHODS

This systematic review was conducted in line with the PRISMA statement. We included all relevant studies published up to June 2022 for analysis. The primary outcomes were overall survival and breast cancer-specific survival (BCSS) of conservative treatment for DCIS.

RESULTS

Three studies, with a total of 34 007 women with low-risk DCIS, were included in the analysis. Active and conservative treatments both resulted in excellent 10-year BCSS, with no statistically insignificant difference (98.6% versus 96.0%, 31 478 women). One study comparing 5-year BCSS of active and conservative treatments only in subjects aged over 80 years also reported [AQ1]an insignificant difference (98.2% versus 96.0%, 2529 women). One study measuring 5- and 10-year overall survival between the treatment groups also reported [AQ1]an insignificant difference (5-year: 96.2% versus 92.4%; 10-year: 85.6% versus 86.7%, 31 106 women).

CONCLUSION

BCSS between active and conservative treatment for women with low-risk DCIS is both excellent and comparable, suggesting that conservative treatment is a possible alternative without compromising survival.

Monovalent versus Divalent Cation Diffusion in Thiospinel Ti2S4

Diffusion coefficients (D) for both Li⁺ and Mg²⁺ in Ti₂S₄ were measured using the galvanic intermittent titration technique (GITT) as a function of both ion concentration (x) and temperature. During discharge at 60 °C, D_Li descends gradually from 2 × 10^-8 cm²/s at x_Li ≈ 0 to 2 × 10^-9 cm²/s at x_Li ≈ 1.9. In contrast, D_Mg decreases sharply from 2 × 10^-8 to 1 × 10^-12 cm²/s by x_Mg ≈ 0.8. This kinetic factor limits the maximum practical discharge capacity of Mg_xTi₂S₄. The difference in behavior vis a vis Li⁺ implies that either increasing Mg²⁺ occupation of the tetrahedral site at x_Mg > 0.6 and/or interactions between diffusing cations play a larger role in mediating the diffusion of divalent compared to monovalent cations. Diffusion activation energies (E_a) extracted from the temperature-dependent data revealed that E_a,Mg (540 ± 80 meV) is about twice that of E_a,Li (260 ± 50 meV), explaining the poorer electrochemical performance of Mg_xTi₂S₄ at room temperature.

Crystal structure of 1-phenyl-imido-1-{6-[1-(phenyl-imino)-eth-yl]pyridin-2-yl}ethan-1-yl-κ3N,N',N'')iron(II)

The title iron complex, [Fe(C21H19N3)2], consists of an FeII atom chelated by two tridentate bis-(imino)-pyridine radical anions in a slightly distorted octa-hedral coordination environment. In the solid state, there are two independent half-mol-ecules in the asymmetric unit, and the complete mol-ecular structure is formed by applying twofold rotation symmetry with the twofold rotation axis passing through an Fe atom. In the crystal, the Fe-containing complexes are not involved in any particular direct inter-molecular inter-actions, with the shortest C-HAr contacts between neighboring phenyl groups being ca 3.2 Å.

Electronic, structural and vibrational induced effects upon ionization of 2-quinolinone

Using first principle methodologies, we characterize the lowest electronic states of 2-quinolinone(+) cation. The ground state of this ion is of X˜(2)A(″) nature. We deduce the adiabatic ionization energy of 2-quinolinone to be equal 8.249eV using the explicitly correlated coupled cluster level and where zero point vibrational energy, core-valence and scalar relativistic effects are taken into account. We examine also the ionization induced structural changes and vibrational shifts and analyze the electron density differences between the neutral and ionic species. These data show that the formation of 2-quinolinone(+)X˜(2)A(″) from 2-quinolinone affects strongly the HNCO group, whereas the carbon skeletal is perturbed when the upper electronic cationic states are populated. The comparison to 2-pyridone allows the elucidation of the effect of benzene ring fused with this heterocyclic ring. Since quinolones and pyridones are both model systems of DNA bases, these findings might help in understanding the charge redistribution in these biological entities upon ionization.

Combined vacuum ultraviolet laser and synchrotron pulsed field ionization study of CH2BrCl

The pulsed field ionization-photoelectron (PFI-PE) spectrum of bromochloromethane (CH2BrCl) in the region of 85,320-88,200 cm-1 has been measured using vacuum ultraviolet laser. The vibrational structure resolved in the PFI-PE spectrum was assigned based on ab initio quantum chemical calculations and Franck-Condon factor predictions. At energies 0-1400 cm-1 above the adiabatic ionization energy (IE) of CH2BrCl, the Br-C-Cl bending vibration progression (nu1+=0-8) of CH2BrCl+ is well resolved and constitutes the major structure in the PFI-PE spectrum, whereas the spectrum at energies 1400-2600 cm-1 above the IE(CH2BrCl) is found to exhibit complex vibrational features, suggesting perturbation by the low lying excited CH2BrCl+(A 2A") state. The assignment of the PFI-PE vibrational bands gives the IE(CH2BrCl)=85,612.4+/-2.0 cm-1 (10.6146+/-0.0003 eV) and the bending frequencies nu1+(a1')=209.7+/-2.0 cm-1 for CH2BrCl+(X2A'). We have also examined the dissociative photoionization process, CH2BrCl+hnu-->CH2Cl++Br+e-, in the energy range of 11.36-11.57 eV using the synchrotron based PFI-PE-photoion coincidence method, yielding the 0 K threshold or appearance energy AE(CH2Cl+)=11.509+/-0.002 eV. Combining the 0 K AE(CH2Cl+) and IE(CH2BrCl) values obtained in this study, together with the known IE(CH2Cl), we have determined the 0 K bond dissociation energies (D0) for CH2Cl+-Br (0.894+/-0.002 eV) and CH2Cl-Br (2.76+/-0.01 eV). We have also performed CCSD(T, full)/complete basis set (CBS) calculations with high-level corrections for the predictions of the IE(CH2BrCl), AE(CH2Cl+), IE(CH2Cl), D0(CH2Cl+-Br), and D0(CH2Cl-Br). The comparison between the theoretical predictions and experimental determinations indicates that the CCSD(T, full)/CBS calculations with high-level corrections are highly reliable with estimated error limits of <17 meV.

A high-resolution pulsed field ionization-photoelectron-photoion coincidence study of vinyl bromide

By employing the high-resolution pulsed field ionization-photoelectron (PFI-PE)-photoion coincidence method, we have examined the unimolecular dissociation reaction of energy-selected C(2)H(3)Br(+) to form C(2)H(3) (+)+Br near its threshold. The analysis of the breakdown curves for C(2)H(3)Br(+) and C(2)H(3) (+) yields a value of 11.9010+/-0.0015 eV for the 0 K dissociative photoionization threshold or appearance energy (AE) for C(2)H(3) (+) from C(2)H(3)Br. This AE(C(2)H(3) (+)) value, together with the ionization energy (IE) for C(2)H(3)Br (9.8200+/-0.0015 eV) obtained by PFI-PE and threshold photoelectron (TPE) measurements, has allowed the determination of the 0 K dissociation energy (D(0)) for the C(2)H(3) (+)-Br bond to be 2.081+/-0.002 eV. The 0 K AE(C(2)H(3) (+)) from C(2)H(3)Br obtained in this study corresponds to DeltaH(f0) ( composite function )(C(2)H(3) (+))=1123.7+/-1.9 kJ/mol. Combining the latter value and the known DeltaH(f0) ( composite function )(C(2)H(3))=306.7+/-2.1 kJ/mol, we calculated a value of 8.468+/-0.029 eV for the IE(C(2)H(3)), which is in accord with the result obtained in the previous photoionization efficiency study. We have also carried out high-level ab initio calculations for the IE(C(2)H(3)) at the Gaussian-3 and the CCSD(T,full)/CBS level of theory. The CCSD(T,full)/CBS prediction of 8.487 eV for the IE(C(2)H(3)-->bridged-C(2)H(3) (+)) is in good agreement with the IE(C(2)H(3)) value derived in the present experiment. Combining the 0 K AE(C(2)H(3) (+))=11.9010+/-0.0015 eV and the IE(C(2)H(3))=8.468+/-0.029 eV yields the value of 3.433+/-0.029 eV for D(0)(C(2)H(3)-Br). We have also recorded the TPE spectrum of C(2)H(3)Br in the energy range of 9.80-12.20 eV. Members (n=5-14) of four autoionizing Rydberg series converging to the C(2)H(3)Br(+)(A (2)A(')) state are observed in the TPE spectrum. The analysis of the converging limit of these Rydberg series and the vibrational TPE bands for C(2)H(3)Br(+)(A (2)A(')) has provided more precise values for the nu(6) (+) (1217+/-10 cm(-1)) and nu(8) (+) (478+/-8 cm(-1)) modes and the IE (10.9156+/-0.0010 eV) for the formation of C(2)H(3)Br(+)(A (2)A(')) from C(2)H(3)Br.

Rovibrational-state-selected photoionization of acetylene by the two-color IR+VUV scheme: observation of rotationally resolved Rydberg transitions

We have demonstrated a rovibrational-state-selected photoionization experiment using an IR laser and high-resolution VUV-synchrotron radiation. The VUV photoionization of acetylene [C2H2(Xtilde; (1)Sigma(+)(g);nu(3)=1,J(')=8 or 10)] prepared by IR excitation reveals three strong autoionizing Rydberg series converging to C2H+2(Xtilde; (2)Pi(u);nu(+)(3)=1) with little ion background interference. Rotational transitions resolved for the Rydberg states provide an estimate of approximately 1.8 ps for their lifetimes. This experiment opens the way for state-selective photoionization studies of polyatomic molecules using VUV-synchrotron radiation.

Preliminary evaluation of "interpreter" role plays in teaching communication skills to medical undergraduates

RATIONALE AND OBJECTIVES

Multiculturalism presents linguistic obstacles to health care provision. We explored the early introduction of "interpreter" role-play exercises in teaching medical undergraduates communication skills. The interpreter role creates a natural barrier in communication providing an active prompt for recognizing learning needs in this area.

METHODS

Bilingual Cantonese first-year medical students (n=160) were randomly allocated to either "Observer" or "Interpreter" role plays at a small-group introductory communication skills workshop using a quasi experimental design, counterbalanced across tutors. Students assessed their own skill competence before and, together with their perceptions of the different role plays' effectiveness, again after the workshop, using an anonymous 16 item Likert-type scale, analysed using ANOVA and MANOVA.

RESULTS

Students' assessments of their skills improved significantly following the workshop (F=73.19 [1,156], P=0.0009). Students in the observer group reported greater changes in their scores following the workshop than did students in the interpreter group (F=4.84 [1,156], P=0.029), largely due to improvement in perceived skill (F=4.38 [1,156], P=0.038) rather than perceived programme effectiveness (F=3.13 [1,156], P > 0.05). Subsequent MANOVA indicated no main effect of observer/interpreter conditions, indicating these differences could be attributed to chance alone (F=1.41 [16 141], P > 0.05).

CONCLUSION

The workshop positively influenced students' perceived communication skills, but the "Interpreter" role was less effective than the "Observer" role in achieving this. Future studies should examine whether interpreter role plays introduced later in the medical programme are beneficial.

Successful radiofrequency ablation in an infant with drug-resistant permanent junctional reciprocating tachycardia

Over the past decade, the technique of radiofrequency ablation has evolved substantially. Currently, most forms of cardiac arrhythmias seen in children can be treated with good long-term results and low risk of adverse outcome. Curative arrhythmia treatment with this technique, however, is still uncommon in neonates and infants. Reported here is our experience in the management of an 8-week-old with drug-resistant permanent junctional reciprocating tachycardia.

Simplified single patch technique for the repair of atrioventricular septal defect

OBJECTIVE

Because of the complexity of traditional 1- and 2-patch techniques for the repair of complete atrioventricular septal defect, we modified our repair technique to avoid the use of any ventricular septal patch material. We report our prospective experience with this simplified 1-patch technique.

METHOD

Forty-seven consecutive patients between May 1995 and August 1998 underwent repair with the use of this technique without modification. Repair was done in all patients by direct suturing of the common atrioventricular valve leaflets to the crest of the ventricular septum. No division of valve leaflets was necessary. A single pericardial patch was used to close the defect in the atrial septal component. Follow-up included electrocardiography and echocardiographic assessment of ventricular function, atrioventricular valve function, and adequacy of the left ventricular outflow tract.

RESULTS

There were 2 deaths (4%), only 1 cardiac related, in the series. There were 17 male patients and 30 female patients. Mean age at repair was 5.6 months (median, 3.4 months). Associated lesions were repaired in 19 patients (40%). Mean follow-up was 1.85 years (median, 1.9 years). There was no heart block. There were no significant residual ventricular septal defects detected and no left ventricular outflow tract obstruction seen on echocardiography in any patient to date. Mitral valve status after operation was assessed as no incompetence in 13 patients (28%), minimal in 19 patients (40%), mild in 12 patients (26%), and moderate in 3 patients (6%).

CONCLUSION

The repair of complete atrioventricular septal defect by direct suturing of the atrioventricular valve leaflets to the crest of the ventricular septum with a single-patch technique greatly simplifies the repair and does not lead to left ventricular outflow tract obstruction nor interfere with valve function.

Supraventricular electrical interaction in conjoined twins with common coronary sinus

Conjoined twins with echocardiographic evidence of continuity of the coronary sinuses had identical heart rates on ECG. Both had broad, polyphasic QRS complexes, and various imaging modalities were unable to determine whether there was ventricular myocardial continuity. Administration of adenosine demonstrated that the broad polyphasic complexes were a "fusion" of the twins' individual QRS complexes, which could be clearly distinguished after administration of the drug. Ventricular pacing resulted in dissociation of the individual QRS complexes, thus demonstrating an absence of ventricular myocardial continuity. This was confirmed when the twins were successfully separated at the age of 10 months.

Radiofrequency catheter ablation in a haemodynamically compromised premature neonate with hydrops fetalis

A preterm infant was born at 35 weeks gestation after failed antenatal antiarrhythmic therapy. The infant had an incessant supraventricular tachycardia, impaired ventricular function and hypotension and failed to respond to adenosine, cardioversion and intravenous amiodarone. After resuscitation from cardiovascular collapse, a successful radiofrequency catheter ablation (RFA) of a left free wall atrioventricular pathway was performed at 24 h of age without extracorporeal support. The infant is normal on follow up at 12 months of age. Whilst most fetal and neonatal supraventricular tachyarrhythmias respond to antiarrhythmic medications and RFA is not required, this is the earliest RFA to be performed on a premature infant when antiarrhythmics have failed.

Radiofrequency catheter ablation of right ventricular outflow tract tachycardia in a preschooler

A 3-year-old girl presented with a febrile illness complicated by right ventricular outflow tract tachycardia, which persisted after resolution of the presumed viral infection. The tachycardia was intermittent, but was significantly exacerbated by exercise. Radiofrequency ablation (RFA) of the ectopic focus was successfully performed and the child remains free of tachycardia 12 months later. A review of the literature suggests that RFA in children is increasingly seen as a safe and convenient option for the treatment of supraventricular tachycardia, whereas the management of ectopic ventricular tachycardia in pediatric practice has not been well defined.

Adenosine in the management of supraventricular tachycardia in children

OBJECTIVE

To assess the efficacy and safety of adenosine in the management of supraventricular tachycardia in children.

METHODOLOGY

A review of 43 children with supraventricular tachycardia who received intravenous adenosine between June 1992 and July 1995.

RESULTS

Thirty-five patients had re-entrant supraventricular tachycardia and eight patients had atrial tachydysrhythmias. Reversion to sinus rhythm occurred in 75% of episodes in all patients treated for supraventricular tachycardia, and in 96% of episodes in patients with re-entrant supraventricular tachycardia. Early re-initiation of supraventricular tachycardia after reversion to sinus rhythm occurred in 25% of episodes. Sixteen percent of patients reverted with the recommended 0.05 mg/kg starting dose, and 35% reverted with a dose of 0.1 mg/kg. Four patients were given adenosine as a diagnostic procedure to elicit occult pre-excitation. The most common side effects were brief feelings of discomfort. No serious side effects occurred.

CONCLUSION

Adenosine is safe and effective in the management of supraventricular tachycardia in children. A commencing dose of 0.1 mg/kg is appropriate.

First prenatal diagnosis of the carnitine transporter defect

We report the first attempt at prenatal diagnosis of the carnitine transporter defect in a fetus at high risk of having the disorder. Analysis of cultured CVS after prolonged culture predicted that the fetus was not affected but might be heterozygous for the carnitine transporter defect, but chromosome 15 satellite DNA markers showed no paternal contribution, suggesting that the CVS cells assayed were of predominantly maternal origin. Subsequent assay of cultured amniocytes predicted that the fetus would be affected, and this was confirmed in the newborn period. We conclude that prenatal diagnosis of the carnitine transporter defect is possible, but where results depend on extended culture of CVS, molecular studies should be performed to confirm genetic contributions from both parents.

The perioperative use of ceftriaxone as infection prophylaxis in neurosurgery

An open label study was conducted in the department of neurosurgery, Beijing Tiantan Hospital in China to determine the incidence of postoperative infections following the use of one or two doses of ceftriaxone administered perioperatively. A total of 343 patients, who required neurosurgery and had satisfied the inclusion criteria, was recruited during a 12 month study period. Of these 343 patients, there were 97 and 107 cases of malignant and benign tumours, respectively, 52 cases of aneurysm, 34 cases of arteriovenous malformation, and 53 other cases who underwent neurosurgery for drainage of sub-dural haematoma, relief of cerebral oedema and other indications. A total of 6 (1.75%) cases of postoperative infection was observed, of which 4 were found in the malignant tumour group, and 2 in the arteriovenous malformation group. All six patients were suffering from meningitis. During the 12 month period immediately prior to the present study, when postoperative penicillin and gentamicin was administered twice daily for 5-7 days as regular prophylaxis against infection, the incidence of postoperative infection was 7.2% in the same department managed by the same staff. Results of our present study suggest that one to two doses of ceftriaxone administered perioperatively are effective in reducing the rate of postoperative infections.

Morphological plasticity of axotomized retinal ganglion cells following intravitreal transplantation of a peripheral nerve segment

During normal development of retinal ganglion cells when the axons are growing, transient dendritic spines have been observed. Similar dendritic spine-like processes are also exhibited by retinal ganglion cells undergoing axonal regeneration into a peripheral nerve grafted to the damaged optic axons. Here we show, using the intracellular injection of Lucifer Yellow, that when a segment of peripheral nerve is transplanted to the vitreous body, a procedure which induces ectopic sprouting of axon-like processes from the cell bodies and dendrites of some retinal ganglion cells, similar spine-like processes appear on the dendrites of cells with ectopic sprouts. Quantitative analysis indicated that there were significant changes with posttransplantation survival time in the distributions of spine-like processes and axon-like processes on these sprouting retinal ganglion cells following the intravitreal transplantation of a piece of peripheral nerve. The remodelling of the spine-like processes and axon-like processes correlated with one another suggesting that plastic changes can occur in certain dendritic subcompartments independent of the growth activity of the other dendritic subcompartments.

NADPH-diaphorase neurons in the retina of the hamster

NADPH-diaphorase-positive neurons have been demonstrated in the inner nuclear layer and ganglion cell layer of the retina of different mammalian species, but so far no experiments have been conducted to identify whether these cells are amacrine cells and/or retinal ganglion cells. We attempted to solve this problem by studying the NADPH-diaphorase-positive neurons in the hamster retina. From the NADPH-diaphorase histochemical reaction, two distinct types of neurons in the hamster retina were identified. They were named ND(g) and ND(i) cells. The ND(g) cells were cells with larger somata, ranging from 10 to 21 microns in diameter with a mean of 15.58 microns (S.D. = 2.59). They were found in the ganglion cell layer only. The ND(i) cells were smaller, with the somata ranging from 7 to 11 microns and having the mean diameter of 8.77 microns (S.D. = 1.24). Most of the ND(i) cells were found in the inner nuclear layer, and only very few could be observed in the inner plexiform layer. On average, there were 8,033 ND(g) and 5,051 ND(i) cells in the ganglion cell layer and inner nuclear layer, respectively. Two experiments were performed to clarify whether any of the NADPH-diaphorase neurons were retinal ganglion cells. Following unilateral optic nerve section, which leads to the retrograde degeneration of retinal ganglion cells, the numbers of both ND(g) and ND(i) cells did not change significantly for up to 4 months. In addition, when retinal ganglion cells were prelabeled retrogradely (horseradish peroxidase or fluorescent microspheres) and retinas were then stained for NADPH diaphorase, no double-labeled neurons were detected. These results indicated that the NADPH-diaphorase neurons in the hamster retina were the amacrine cells in the inner nuclear layer and displaced amacrine cells in the ganglion cell layer. Dendrites of the ND(g) and ND(i) cells were found to stratify in sublaminae 1, 3, and 5 of the inner plexiform layer, with a prominent staining in the sublamina 5. The possible importance of this arrangement in the rod pathway is also discussed.

Primary intraventricular cardiac tumors in children: contemporary diagnostic and management options

We reviewed the intraventricular cardiac tumors presenting at our institution between 1985-1991, studying the presentation, modes of investigation, and evidence of hemodynamic compromise. Thirteen patients presented with intraventricular tumors during the study period. Two of the tumors were rhabdomyosarcomas, one was a myxoma, and 10 were rhabdomyomas. All patients were evaluated with two-dimensional and pulsed Doppler echocardiography and B-color imaging was undertaken in three patients. Four patients presented for elective scans to complement investigations for tuberous sclerosis, seven patients had cardiac symptoms, and two patients presented prenatally. Obstruction to intracardiac flow was present in five patients. Two patients had the tumor excised and one had an open biopsy of the tumor. One patient had an transvascular biopsy at cardiac catheter. Early detection of cardiac tumors is increasing, particularly rhabdomyomas. With fetal echocardiography, more patients should come to attention prenatally. B-color may be useful addition in assessing cardiac tumors, aiding detection and definition of intramural lesions.

Amiodarone management of junctional ectopic tachycardia after cardiac surgery in children

OBJECTIVE

To assess the effectiveness and safety of amiodarone in the treatment of junctional ectopic tachycardia (JET) after open heart surgery in children.

PATIENTS

Between January 1990 and December 1991, 16 consecutive patients aged 6 days to 14 years with JET associated with significant haemodynamic impairment after cardiopulmonary bypass were treated with amiodarone as the principal antiarrhythmic drug.

INTERVENTIONS

Amiodarone 5 mg/kg was administered intravenously over one hour and the same dose was subsequently infused over 12 hours. This was reviewed every 12 hours and repeated as necessary until a satisfactory heart rate and stable haemodynamics were achieved. Atrial pacing was used whenever possible to provide atrioventricular synchrony.

RESULTS

Except for one patient with a JET rate of 160/min, the maximum JET rate ranged from 180/min to 245/min with a mean(SD) of 200 (20)/min. After amiodarone, the heart rates reduced to a mean(SD) of 170 (20), 164 (27), 158 (27), 157 (24), and 153 (19)/min at two, four, eight, 12, and 24 hours respectively. A reduction in tachycardia rate allowing atrial pacing was achieved in 10 patients by two hours. Haemodynamic variables improved in most patients with an increase in mean systolic blood pressure by an average of 15 mm Hg and a decrease in atrial filling pressures by an average of 3.5 mm Hg at four hours after amiodarone administration. There were three deaths: one was a moribund patient who died soon after the onset of JET and the other two deaths were not directly related to JET.

COMPLICATIONS

Late bradycardia with hypotension was recorded in one patient. Asymptomatic late sinus bradycardia was seen in several others.

CONCLUSIONS

Amiodarone can be used safely and effectively to control JET with haemodynamic improvement in most patients. The addition of atrial pacing confers the advantage of atrioventricular synchrony.

Intravitreal transplantation of a segment of peripheral nerve enhances axonal regeneration of retinal ganglion cells following distal axotomy

Neurons of the central nervous system are able to regenerate their axons into a peripheral nerve (PN) graft when they are axotomized close to the cell bodies. Very few, if any, damaged axons can regrow into the PN graft when the axonal injury is made distant to the cell bodies. We show here that a segment of viable PN transplanted intravitreally enhances the regenerative response of distally axotomized retinal ganglion cells. We hypothesize that trophic substances released from the intravitreal PN segment may enable retinal ganglion cells to regenerate their damaged axons into the PN graft even after a distal axotomy. This suggests that the regenerative behavior of an axotomized neuron is influenced by both the local environment at the damaged tip of the axon and the local environment surrounding the cell body. This finding provides evidence that the PN grafting technique may be useful for repairing long tract pathways in the central nervous system even when the damage is inflicted far away from the cell bodies.

Posterior ("atypical") atrioventricular junctional reentrant tachycardia

The aim of this study was to characterize a relatively rare type of atrioventricular (AV) junctional reentrant tachycardia (AVJRT). Posterior AVJRT is a type of AV nodal tachycardia in which the site of earliest atrial activation is posterior to the AV node near the coronary sinus orifice. The mechanism of this tachycardia is not well understood. The characteristics of posterior AVJRT (n = 15) were compared with those of anterior ("common") AVJRT (n = 146) and supraventricular tachycardia using single posterior septal accessory pathways (n = 13). During posterior AVJRT, the AH interval was longer than the retrograde conduction time (His to earliest atrial activity) in 11 cases (73%), indicating that these tachycardias were not fast-slow types of AVJRT. The mean ventriculoatrial (VA) interval in posterior AVJRT (93 +/- 41 ms) was longer than in anterior AVJRT (11 +/- 20 ms; p < 0.005), but was similar to that in tachycardias using accessory pathways (106 +/- 16 ms; p = NS). The site of earliest atrial activation during posterior AVJRT was similar to that in tachycardias using accessory pathways. In all cases of accessory pathway-mediated tachycardia, atrial activation could be advanced by ventricular extrastimuli delivered coincident with the His deflection, but atrial activation was not advanced in any case of posterior AVJRT unless the extrastimulus was delivered > 80 ms before the His deflection. Anterograde conduction was similar in the posterior and anterior AVJRT groups.(ABSTRACT TRUNCATED AT 250 WORDS)

APV prevents the elimination of transient dendritic spines on a population of retinal ganglion cells

Blockade of the N-methyl-D-aspartate (NMDA) receptors on retinal ganglion cells (RGCs) during development prevents the elimination of the exuberant spine-like processes in a population of Type I RGCs in hamsters. During the development of RGCs, exuberant dendritic spines have been observed which disappear during maturation. Blocking the NMDA receptors on developing RGCs with the antagonist, DL-2-amino-5-phosphonovaleric acid (APV) and the subsequent retention of some of the normally transient dendritic spines suggest that the morphological development of post-synaptic neurons may be affected by this treatment. Our result further suggests that the elimination of exuberant spines during normal development requires interactions between receptors on the spines and neurotransmitters released by the pre-synaptic inputs.

Pupillary constriction in response to light in rodents, which does not depend on central neural pathways

We show here that the widely held belief that reflex constriction of the mammalian pupil in response to light depends exclusively upon neural pathways between eye and brain is in need of revision. We investigated the response of the pupil to light in dark-adapted rodents (golden hamsters; hooded rats; albino rats) subjected to a variety of surgical and pharmacological interventions designed to destroy or block all of the neural pathways and structures through which the reflex could be mediated. The interventions included bilateral intraorbital optic nerve section, or unilateral intracranial optic nerve section with enucleation of the contralateral eye, combined in some cases with bilateral removal of the superior cervical ganglia and/or pinealectomy; topical application of atropine; intraocular injection of tetrodotoxin (TTX). Golden hamsters and hooded rats, but not albino rats, retained an effective constriction of the pupil in response to light after all of these interventions, although the constriction was less and slower than in normal animals. These findings show that hamsters and hooded rats have both a neurally mediated fast light reflex that can be eliminated by severing connections between eye and brain, by blockade of cholinergic transmission to iris smooth muscle, and by blockade of action potentials by TTX; and a local, slower constriction in response to light, which remains after all these procedures. We have also confirmed previous observations of Bito and Turansky (1975) that pupillary constriction in response to light occurs in isolated in vitro anterior chamber preparations of hamster and hooded rat eyes.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy of various methods of localization of the orifice of the coronary sinus at electrophysiologic study

The coronary sinus (CS) orifice is an important reference point for determining electrode and, thereby, accessory pathway location at electrophysiologic study. The reliability of fluoroscopic landmarks used to identify the CS orifice is not known. This study compared the accuracy of several fluoroscopic landmarks for identifying the CS orifice with the location defined by radiopaque contrast injection of the CS. Forty patients were studied. Radiographic markers of the CS orifice that were examined included: (1) the point at which the CS catheter prolapsed during advancement, (2) the point of maximum convexity of the CS catheter when a superior vena caval approach was used, (3) the right side of the ventricular septum, and (4) the relation to the underlying vertebrae. The least-significant difference method of multiple comparisons was used for statistical analysis. The point at which the CS catheter prolapsed was the most accurate noncontrast method for determining the location of the CS orifice (p less than 0.05), but was possible without the use of excessive force in only 48% of patients. The point of catheter prolapse was a median of 1 mm (range 0 to 11) from the true location of the os. Errors with other examined landmarks ranged up to 3 cm. Identification of the CS orifice is best performed by radiopaque contrast injection. The point of prolapse during catheter advancement in the CS is an accurate alternative when contrast injection is not feasible. Other noncontrast fluoroscopic landmarks are less reliable and are best avoided.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal development of type I retinal ganglion cells in hamsters: a lucifer yellow study

The postnatal development of a population of superior colliculus projecting retinal ganglion cells with large somata in hamsters aged from postnatal day (P) 4 to adult was studied by the intracellular injection of Lucifer Yellow. This population of cells was interpreted as Type I cells based on their large soma sizes and dendritic morphology resembling that of mature Type I cells. In addition to the growth of the soma and the dendritic field, transient morphological features such as intraretinal axon collaterals and exuberant dendritic spines, but not somatic spines, were frequently observed on this population of cells in hamsters during development. None of them exhibited any intraretinal axon collaterals after P7. The number of transient spine-like processes on dendrites increased from P4 onwards to reach a peak at P16, decreased abruptly within a few days after the peak, and stabilised to reach the adult level by P30. These developing cells attained the maximum number of dendritic branches by P16 and there seems to be little, if any, reduction in the number of branch points after this time point. In addition, the length of individual branches of dendrites was not increased excessively during development and then shortened during maturation. Thus, the dendritic remodeling of these cells after P16 seems to be mainly the increase of the length of dendrites and the removal of exuberant dendritic spines.

Permanent junctional reciprocating tachycardia misdiagnosed as 'cardiomyopathy'

In a nine-year-old female, cardiac failure was erroneously attributed to idiopathic cardiomyopathy and cardiac transplantation was planned. The actual cause of cardiac failure was permanent junctional reciprocating tachycardia (PJRT), a rare form of supraventricular tachycardia. The diagnostic error was discovered before transplantation was performed and the arrhythmia was treated surgically. This resulted in return of near normal cardiac function.

Patients with two types of atrioventricular junctional (AV nodal) reentrant tachycardia. Evidence that a common pathway of nodal tissue is not present above the reentrant circuit

BACKGROUND

The site of the reentrant circuit in atrioventricular (AV) junctional reentrant tachycardia has not been defined; in particular, the existence of a common pathway of AV nodal tissue above the reentrant circuit is controversial.

METHODS AND RESULTS

Two types of AV junctional reentrant tachycardia were induced in each of three patients at electrophysiological study. In one type of tachycardia (anterior), the onset of atrial activity occurred from 0 to 12 msec before the onset of ventricular activation, and earliest atrial activity was recorded near the His bundle. In the second type of tachycardia (posterior), the ventriculoatrial intervals were longer (76-168 msec), and earliest atrial activity was recorded near the mouth of the coronary sinus. In individual patients, the two types of tachycardia had different cycle lengths. Posterior AV junctional reentrant tachycardia was not a fast-slow form of AV junctional reentry in at least two of the three patients. Surgical cure was attempted in two patients. In one patient, anterior AV junctional reentrant tachycardia was abolished by dissection of the anterior perinodal atrium, but posterior AV junctional reentrant tachycardia could still be induced. At reoperation 4 months later, dissection of the posterior perinodal atrium abolished posterior AV junctional reentrant tachycardia while preserving AV conduction.

CONCLUSION

Differences in ventriculoatrial intervals and cycle lengths and the results of selective surgery suggest that the two types of AV junctional reentrant tachycardia used different reentrant circuits. These observations imply that a common pathway of AV nodal tissue is not present above the reentrant circuit and suggest that perinodal atrium is part of these circuits.

Elimination of transient dendritic spines in ipsilaterally projecting retinal ganglion cells in rats with neonatal unilateral thalamotomy

Using the DiI and intracellular Lucifer Yellow labeling techniques in the rat, we have demonstrated that the unilateral neonatal thalamotomy does not result in retention of transient dendritic spines of ipsilaterally projecting retinal ganglion cells (IPRGCs), although the thalamotomy is known to retain the normally transient IPRGCs (Chan et al., Dev. Brain Res., 49 (1989) 265-274). These results suggest that the process of elimination or retraction of transient dendritic spines occurs in retinal ganglion cells during development regardless of whether they make connections with appropriate or inappropriate loci in the visual targets, and/or a decrease in interactions with neighboring retinal ganglion cells.

Effects of visual or light deprivation on the morphology, and the elimination of the transient features during development, of type I retinal ganglion cells in hamsters

Intracellular injection of Lucifer Yellow (LY) was used to study the detailed morphology of the normal visually deprived, and light-deprived superior colliculus projecting Type I retinal ganglion cells (RGCs) in hamsters. The soma size of the normal Type I cells ranged from 337 to 583 microns 2 with a mean of 436 microns 2. Two to six primary dendrites were observed in these cells. The mean dendritic field diameter was 495 microns and ranged from 309 to 702 microns. The dendritic field diameter of this population of cells exhibited an eccentricity dependence. Quantitative comparisons between the normal and visually deprived or light-deprived Type I RGCs indicated that the morphology of these three groups of cells were similar to each other in terms of the soma size, dendritic field diameter, branching pattern, and total length of the dendrites. During the normal development of cats and hamsters, several transient features, such as exuberant dendritic spines and intraretinal axonal branches, have been observed in the developing RGCs. The complete elimination of these transient features occurs at about 3 and 2 weeks after the opening of the eyes in cats and hamsters, respectively. In the present study, the hypothesis whether visual experience or light stimulation is required for the elimination of these transient features during development was examined. After studying a total of 115 mature Type I RGCs, which included cells from the normal, visually deprived and light deprived animals, no transient feature was observed. We conclude that visual or light deprivation has no effect on the morphological development of superior colliculus projecting Type I RGCs in hamsters, and the elimination of the transient features on the Type I RGCs during development does not depend on visual experience or light stimulation.

Incessant ventricular tachycardia in infancy

Two infants with incessant tachycardia uncontrolled by multiple drug treatment were thought initially to have supraventricular tachycardia. Careful examination of the 12-lead electrocardiogram suggested ventricular tachycardia, which was confirmed by electrophysiological studies. Intra-operative mapping showed that the arrhythmia arose from the posterior left ventricular free wall in one infant and at the left ventricular apex in the other. Cryoablation of these foci led to cessation of ventricular tachycardia. Myocardial biopsy showed hamartomatous involvement in the first infant and normal tissue in the other. In the first infant the incessant arrhythmia was cured but in the other it recurred 4 months later. The origin of the recurrent tachycardia was adjacent to the previously cryoablated arrhythmogenic area. This area was also cryoablated, leading to disappearance of the ventricular tachycardia. Both patients are free of arrhythmia 10 months and 3 months after their surgery. Surgically ablatable lesions are common in infants with incessant ventricular tachycardia. Early diagnosis and prompt surgical treatment usually can effect 'cure' of this potentially fatal problem in childhood.

Electrophysiological study in supraventricular tachycardia

Supraventricular tachycardia is a common clinical problem. Although its primary mortality is usually low, it often causes significant life long symptoms. It can be life threatening when associated with rapidly conducting accessory atrioventricular connections or nodo-ventricular fibres. Electrophysiological study is now the "gold standard" investigation for diagnosis of this problem. It is also an essential tool for choosing therapeutic options. It is safe and cost effective and should be available in all major hospitals. Since surgical cure is currently feasible for almost all forms of supraventricular tachycardia with a high success rate and a low mortality, electrophysiological study and arrhythmia surgery should be offered to symptomatic patients early in the course of disease. Catheter ablation of supraventricular tachycardia is presently investigational but may in the future become the standard treatment for some forms of supraventricular tachycardia if the cure rate and risk of the procedure can be improved so that they are superior to surgery.

Left ventricular function in beta thalassaemia major

The left ventricular dimension and posterior wall dynamics were studied by computer assisted analysis of M mode echocardiography in 25 normal children (group 1) and 32 transfusion dependent children with beta thalassaemia major who had no evidence of heart failure (group 2). Twenty seven of those in group 2 remained well but five died of cardiac decompensation within 12 months. Compared with group 1, the left ventricular fractional shortening and ejection fraction were normal in those in group 2 who survived but diminished in those who died. Evaluation of left ventricular dimension and posterior wall dynamics during systole (peak shortening rate, peak velocity of circumferential fibre shortening, and peak posterior wall thickening rate) showed similar findings in that only the group who died had abnormal values. The left ventricular dimension and posterior wall diastolic dynamics (peak relaxation rate, normalised peak relaxation, peak wall thinning, and normalised peak wall thinning rate), however, showed progressively slower rates in all the children in group 2. The findings suggest that left ventricular diastolic dysfunction occurs early in myocardial impairment in patients with beta thalassaemia major. When there are abnormalities in both diastole and systole, the myocardial impairment is advanced and the prognosis is poor.

Congenital cardiovascular malformations in Chinese children with Down's syndrome

149 Chinese children (70 boys, 79 girls) with Down's syndrome and congenital heart disease were studied. Diagnosis of the cardiac abnormality was made by cardiac catheterisation in 119, two-dimensional echocardiography in 23 and autopsy in 7. The commonest lesion was ventricular septal defect which was present in 43.6%, a higher frequency than that reported in Caucasians. Other common lesions included atrioventricular septal defect (15.4%), atrial septal defect (13.4%), tetralogy in Fallot (13.4%) and patent ductus arteriosus (12.1%). Multiple lesions occurred in 36% of the cases, with patent ductus arteriosus, the most frequent coexisting lesion. Other cyanotic congenital heart conditions were very rare and coarctation of aorta was not seen. An aberrant right subclavian artery arising from the descending aorta was present in 16.5% and abnormalities of the radial artery at the wrist were found in 19%. The literature on patterns of congenital heart diseases seen in Down's syndrome was reviewed.

Axillary artery counter-current aortography in the newborn with aortic arch obstruction

13 newborn infants with aortic coarctation were evaluated by counter-current aortographic technique. The right radial or brachial artery approach (2 cases in each group) did not give successful aortic arch imaging while the right axillary artery approach resulted in adequate imaging in each of 9 cases investigated. In 2, the axillary artery was transiently weakened but returned to normal within 24 h. No other complications were encountered. Axillary artery counter-current aortography is a safe and relatively non-invasive procedure which can be used to image the aortic arch in the newborn babies when other non-invasive diagnosis of aortic arch obstruction is tentative.

Complete heart block after balloon dilatation for congenital pulmonary stenosis

Permanent complete heart block developed in a five year old child during balloon dilatation for pulmonary valve stenosis. Damage to the atrioventricular node by pressure from the inflated balloon may have caused the conduction defect.

Cross-sectional and pulsed Doppler echocardiography of the atrioventricular junction of hearts with univentricular atrioventricular connexion

The atrioventricular junction of 52 consecutive patients with univentricular atrioventricular connexion was examined by cross-sectional and pulsed Doppler echocardiography. The echocardiographic features were then compared with catheterisation and cineangiographic findings. In the diagnosis of the mode of atrioventricular connexion, cross-sectional echocardiography was superior to cineangiography in differentiating single inlet with absence of one atrioventricular connexion from double inlet with a common atrioventricular valve. Straddling atrioventricular valves were diagnosed by echocardiography alone. Using pulsed Doppler echocardiography, the diagnostic sensitivity of atrioventricular valvar regurgitation was 92.6% and the specificity 100%. By mapping the regurgitant jet with pulsed Doppler echocardiography, an index was derived to evaluate the severity of atrioventricular valvar regurgitation. The indices obtained correlated well with cineangiographic grading on a three-point scale (Spearman rank correlation coefficient: rs = 0.9). Thus, cross-sectional echocardiography coupled with a range-gated Doppler system provide accurate anatomical details of the atrioventricular junction and reliable assessment of atrioventricular valvar regurgitation in patients with univentricular atrioventricular connexion.

Aortic atresia with complete transposition

Aortic atresia with ventriculoarterial discordance in a three day old neonate was studied by cross sectional echocardiography and the anatomy was confirmed at necropsy.