Evaluation of the behaviour of a thermal diffusion sensor in a high field strength magnetic resonance system: an experimental study.

Patients with acute brain pathology requiring ferromagnetic bio-medical implants for on-going invasive monitoring are largely excluded from the benefits of MRI scanning. We evaluated the behaviour of a thermal diffusion cortical blood flow (TD-CBF) sensor both in vitro (phantom gelatin model) and in vivo environments in a high field strength MRI system.Two baboons underwent cranial subdural implantation of 2 TD-CBF sensors/hemisphere and a single left parietal sensor was implanted subcortically to determine any deleterious effects. Using standard MRI sequences, artefact size, thermal effects, current generation, movement and reliability of recordings were assessed during scanning.The deflection forces were negligible, no observable thermal effects were demonstrated, while wide fluctuations in cerebral blood flow recordings were recorded. Mean image artefact size for implanted sensors was 6 times larger than in vitro. Patients with an implanted TD-CBF sensor may be safely imaged provided the device is disconnected. The MRI images obtained are of an acceptable quality.     

Impact of Retrograde Cerebral Perfusion on Ascending Aortic and Arch Aneurysm Repair

Purpose. The effect of retrograde cerebral perfusion on the incidence of stroke and death among patients undergoing repair of aneurysms of the ascending aorta and transverse arch was determined.

Material and Methods. Between January 1991 and March 1995, 161 patients were operated on for aneurysms of the ascending aorta and transverse arch. Thirty-three of the patients (20%) had an aneurysm of the ascending aorta only and 128 (80%) had aneurysms of both the ascending aorta and the transverse arch. All the patients underwent cardiopulmonary bypass, profound hypothermia, and circulatory arrest, and 120 (74%) also underwent retrograde cerebral perfusion. Median pump time was 143 minutes (range, 21 to 461 minutes). Median circulatory arrest time was 42 minutes (range, 8 to 111 minutes), and median myocardial ischemic time was 71 minutes (range, 14 to 306 minutes).

Results. The overall 30-day mortality rate was 6% (9 patients) and the incidence of stroke was 4% (7 patients). The use of retrograde cerebral perfusion demonstrated a protective effect against stroke (3 of 120 patients, or 3%) compared with no retrograde cerebral perfusion (4 of 41 patients, or 9%; odds ratio, 0.24; confidence interval, 0.06 to 0.99; p < 0.049). This was most significant in patients more than 70 years of age; none of the 36 elderly patients who received retrograde cerebral perfusion had a stroke, compared with 3 of the 13 (23%) who did not (p < 0.003). Only pump time was associated with an increased risk of stroke (odds ratio, 1.01; 95% confidence interval, 1.00 to 1.02; p < 0.005). Pump time also was associated with increased mortality (odds ratio, 1.01; 95% confidence interval, 1.00 to 1.02; p < 0.008).

Conclusion. Retrograde cerebral perfusion decreased the incidence of stroke in patients undergoing repair of aneurysms of the ascending aorta and transverse arch.     

Pulmonary function in healthy young adult Indians in Madras.

Forced vital capacity, forced expiratory volume in one second, functional residual capacity, residual volume, total lung capacity, and single breath diffusing capacity measurements (effective alveolar volume, carbon monoxide transfer factor, and transfer coefficient) were measured in 247 young healthy adults (130 male, 117 female) aged 15-40 years living in Madras. Subjects were of Dravidian stock, living at sea level with rice as their staple diet. Regression equations were derived for men and women for predicting normal pulmonary function for young adults in South India. The values were similar to those reported for subjects from Western India and lower than those reported for North Indians and caucasians.     

Molecular detection of the G(-248)A BAX promoter nucleotide change in B cell chronic lymphocytic leukaemia.

BACKGROUND: A novel single nucleotide polymorphism (SNP), G(-248)A, in the 5' untranslated region of the BAX promoter and its association with reduced protein expression, progression beyond Rai stage 0, and treatment resistance in chronic lymphocytic leukaemia (CLL) has been reported previously. AIM: To develop a restriction enzyme analysis (REA) based method for routine detection of BAX promoter SNP in a clinical laboratory. METHODS: The BAX promoter was analysed in duplicate by REA and sequencing in 90 samples (from 45 patients with CLL, 43 controls, and two cell lines). The promoter region was amplified, digested with restriction endonucleases (Aci I and Tau I), and separated by gel electrophoresis. RESULTS: After digestion, the normal GG genotype samples produced three distinct bands. The homozygous AA replacement abolished the cleavage site, resulting in a single band. Although the heterozygous samples produced three bands, the two smaller visible bands were reduced in intensity (> 50%). The test characteristics of Aci I REA were better than those of Tau I REA, in terms of sensitivity (100% v 77.8%), specificity (98.6% v 92.3%), positive predictive value (95.03% v 87.4%), and negative predictive value (100% v 85.83%). CONCLUSIONS: REA using Aci I is a highly sensitive and specific method for detecting the BAX G(-248)A SNP in CLL.