Airflow measurement inaccuracies in aerosol imaging

Aerosol production using inclined compressed air tanks may be subject to error caused by airflow meter variability and by the degree of inclination of the air-flow meter. Since most of these tanks are used in an inclined position, it is important for clinicians to be aware of these errors.     

Characterization of survival motor neuron (SMNT) gene deletions in asymptomatic carriers of spinal muscular atrophy

Previous reports have established that the telomeric copy of the survival motor neuron (SMNT) gene and the intact copy of the neuronal apoptosis inhibitory protein (NAIP) gene are preferentially deleted in patients with spinal muscular atrophy (SMA). Although deletions or mutations in the SMNT gene are most highly correlated with SMA, it is not clear to what extent NAIP or other genes influence the SMA phenotype, or whether a small fraction of SMA patients actually have functional copies of both SMNT and NAIP. To evaluate further the part of SMNT in the development of SMA, we analyzed 280 asymptomatic SMA family members for the presence or absence of SMNT exons 7 and 8. We report the following observations: (i) 4% of the sample harbored a polymorphic variant of SMNT exon 7 that looks like a homozygous deletion; (ii) approximately 1% of the parents are homozygously deleted for both exons 7 and 8; (iii) one asymptomatic parent lacking both copies of SMNT exons 7 and 8 displays a 'subclinical phenotype' characterized by mild neurogenic pathology; (iv) another asymptomatic parent lacking both SMNT exons showed no signs of motor neuron disorder by clinical and neurodiagnostic analyses. The demonstration of polymorphic variants of exon 7 that masquerade as homozygous nulls, and the identification of SMA parents who harbor two disease alleles, serve as a caution to those conducting prenatal tests with these markers.      

What can we learn about the need for transfusion from patients who refuse blood? The experience with Jehovah's Witnesses

BACKGROUND: A transfusion threshold of 7 g per dL (70 g/L) of hemoglobin has been proposed for patients, although scant human data are available to support this recommendation. STUDY DESIGN AND METHODS: The medical community's experience with Jehovah's Witnesses was examined, in order to assess the lowest tolerable hemoglobin concentration and the lower transfusion threshold of 7 g per dL (70 g/L) of hemoglobin. A MEDLINE search was conducted to capture medical and surgical reports involving Jehovah's Witnesses from 1970 through early 1993. RESULTS: Sixty-one reports of untransfused Jehovah's Witnesses with hemoglobin concentrations < or = 8 g per dL (80 g/L) or hematocrits < or = 24 percent (0.24) were identified. Of 50 reported deaths, 23, as stated in the original reports, were primarily due to anemia. Except for three patients who died after cardiac surgery, all patients whose deaths were attributed to anemia died with hemoglobin concentrations < or = 5 g per dL (50 g/L). Twenty-five survivors were reported with hemoglobin < or = 5 g per dL (50 g/L). CONCLUSION: These data have significant limitations but suggest that survival, without transfusion, is possible at low hemoglobin concentrations, while mortality with an unknown incidence is encountered at hemoglobin concentrations below 5 g per dL (50 g/L).     

Increased diarrhoeal and respiratory morbidity in association with zinc deficiency—a preliminary report

Plasma zinc levels, in a cohort of 116 children aged 12–59 months recently recovered from an episode of acute diarrhoea attending a community health clinic in an urban slum, were related to diarrhoeal and respiratory morbidity in the 3 month period following recovery. Children with low plasma zinc levels (< 60 μg dl⁻¹) spent a significantly greater number of days with watery diarrhoea (rate ratio 1.69 (95% confidence intervals 1.03-2.78)), diarrhoea associated with fever (rate ratio 1.88 (95% confidence intervals 1.05-3.34)), and acute lower respiratory tract infections (rate ratio 2.69 (95% confidence intervals 1.64-4.38)).     

Automatic implantable cardioverter-defibrillator: radiographic appearance

The automatic implantable cardioverter-defibrillator is used in patients with ventricular tachyarrhythmias resistant to medical or surgical therapy. The device, which has a unique radiographic appearance, senses ventricular tachycardia or fibrillation and automatically delivers a cardioverting or/defibrillating electric shock.