Initiating Sequences in Exercise Induced Idiopathic Ventricular Tachycardia of Left Bundle Branch-Like Morphology

Initiating Sequences in Exercise Induced Idiopathic Ventricular Tachycardia of Left Bundle Branch-Like Morphology. Initiating sequences for VT may infer the underlying arrhythmogenic mechanisms. This study examines the initiating sequences of exercise induced idiopathic VT of left bundle branch block-like (LBBB-like) morphology and makes an attempt to relate these to clinical aspects and the mechanisms of arrhythmia. Thirty-two patients (mean age 33.4 ± 13.2 years; 18 men) with exercise induced VT in the absence of structural cardiac abnormality on history, clinical examination, and noninvasive and invasive investigations were divided into two groups on the basis of the initiating sequence of VT on exercise. Group I consisted of patients with long-short sequence of RR intervals prior to the onset of VT (initiating/preinitiating cycle length ratio < 0.78). Group II consisted of patients without changes in cycle length prior to VT. Group I mechanism would suggest delayed afterdepolarizations (DADs) or reentry whereas group II mechanism triggered activity due to early afterdepolarizations. Fourteen patients (group I) had long-short sequence and 18 patients (group II) were without cycle length changes prior to VT initiated during exercise. VT axis was inferior in all 18 patients in group II but only in 9 patients in group I (P = 0.02). In these predefined patient groups, sustained monomorphic VT could not be initiated by programmed stimulation in any patient in group I, whereas four patients in group II had inducible VT. Patients in group II also had higher incidence of sustained VT on ambulatory monitoring (P < 0.05). The two groups did not differ in other respects. This study demonstrates the existence of at least two possible mechanisms of initiation of exercise induced idiopathic VT of LBBB-like morphology. VT initiated without cycle length changes is more common, more likely to have an inferior axis suggesting an outflow tract origin, and is probably related to triggered activity secondary to DADs. VT initiated with a long-short sequence is more often nonsustained and may have a superior axis suggesting an origin from the body or septal region of the ventricle. The two groups, therefore, exhibit differences in electrophysiological characteristics that may aid classification and therapy of this arrhythmia.     

Treatment of urethral stones by retrograde manipulation and extracorporeal shock wave lithotripsy

Objective To assess the effect of retrograde manipulation and extracorporeal shock wave lithotripsy (ESWL) as a monotherapy for urethral stones that are not associated with urethral strictures. Patients and methods Between August 1993 and January 1995, 34 male patients (mean age 38.7 years, range 7–55) presented with urethral stones. No patient had a suggested or past history of urethral stricture. Lidocaine jelly (2%) was instilled and retained inside the urethra for 5 min. A 16 F urethral catheter was advanced gently to push the stone back to the urinary bladder. Twenty patients had ESWL of their stones in the bladder, using a Storz Modulith SL20, in the prone position. Tilting the patient about 15° towards the side with the stone minimized movement of the stone during fragmentation. In-line co-axial echography (3.5 MHz) and intermittent pulsed fluoroscopy were used to monitor stone fragmentation. In situ fragmentation of posterior urethral stones was not possible because localization was difficult and the treatment was painful. Thirteen patients had cysto-urethroscopy and mechanical cystolitholapaxy under general anaesthesia. Results Stones impacted in the posterior urethra in 31 (91%) patients and in the anterior urethra in three (9%) patients. Stones ranged in size from 7 to 25 mm. One patient expelled an anterior urethral stone after the instillation of 2% lidocaine jelly. The urethral stones were pushed back to the bladder without complication in the remaining 33 patients. All 20 patients except one had their stones fragmented by ESWL in one session. The mean number of shock waves was 3600 ± 1480 (range 1200–6000) and the generator voltage ranged between 5 kV (560 bar) to 8 kV (940 bar). No patient in the ESWL group required anaesthesia or analgesia. Thirteen patients had successful mechanical cystolitholapaxy with no complications. Conclusion Both endoscopic lithotripsy and ESWL of urethral stones are safe and effective. However, transurethral lithotripsy requires general anaesthesia and carries a risk of bladder and urethral trauma. This study demonstrated that, in the absence of urethral stricture, urethral stones can be pushed back safely to the urinary bladder and fragmented effectively by ESWL. The success of the treatment depends on adequate anaesthesia of the urethra before inserting the urethral catheter. We propose that this new technique should be considered before resorting to endoscopic or surgical management of urethral stones, particularly in children.     

Crystal structure and conformation of the cyclic tetramer of a repeat tripeptide of elastin,cyclo(l-valyl-l-prolylglycyl)4

X-ray diffraction data were used to determine the crystal structure of cyclo-(l -Val-l -Pro-Gly)₄, the cyclic tetramer of a repeat tripeptide of elastin. The crystals are monoclinic, space group C2, with a = 29.639(3), b = 7.099(1), c = 20.325 (2) Å, and β = 130.4(4)°. The structure was solved by direct methods and refined by least squares to R = 0.082 for 2603 observed reflections. The cyclic dodecapeptide contains two β(II) turns. Hydrophilic and hydrophobic channels that run parallel to the b axis are formed by the stacking of cyclic peptides on twofold axes.     

Conformation of a cyclic decapeptide analog of a repeat pentapeptide sequence of elastin: cyclo-bis(valyl-prolyl-alanyl-valyl-glycyl)

The conformation of a cyclic decapeptide analog of a repeat sequence of elastin has been determined in the crystalline state using X-ray crystallographic techniques. Tetragonal crystals were grown from a solution of the decapeptide in water; space group P4₂2₁2, a = 19.439(2) & c = 13.602(1) Å, with four formula units (C₄₀H₆₆N₁₀O₁₀·4H₂O) per unit cell. The cyclic decapeptide in the crystal exhibits exact twofold symmetry. The asymmetric unit contains one pentapeptide and two water molecules for a total of 32 nonhydrogen atoms. The structure has been determined by the application of direct methods and refined by full-matrix least squares to an R index of 0.053 for 2272 reflections with intensities greater than 2σ(I). The backbone conformation of the asymmetric pentapeptide can be described as consisting of a double β bend of Type III-I. The Type III turn has Pro (ρ= -59.3°, Ψ= -26.8°) and Ala (ρ= -65.9°, Ψ= -23.1°) at the corners while Type I turn has Ala (ρ= -65.9°, Ψ= -23.1°) and Val (ρ= -98.9°, Ψ= 8.3°) as the corner residues. The cyclic decapeptide has two such double bends linked together by Gly-Val bridges.     

Clinical profile, laboratory characteristics and outcome in miliary tuberculosis

We report a retrospective series of 100 non-HIV adult patientswith miliary tuberculosis (MTB) treated in a tertiary care centre.There were 51 males. Their mean age was 35 years. Predisposingconditions existed in 34. Twelve patients had larger-than-miliary(>2mm) shadows in their chest roentgenograms. Five presentedwith acute respiratory failure, and early treatment cured fourof them. Hyponatraemia occurred in 42/60 patients (70%) forwhom values were available. Twelve patients (12%) died of MTB.Temperature