Peripheral nerve stimulation during MRI: Effects of high gradient amplitudes and switching rates

The application of high gradient amplitudes and switching rates for MRI and spectroscopy, resulting in short rise times for the gradient field and high changes of the magnetic flux density in the patient, is known to possibly evoke peripheral nerve stimulation (PNS) in patients. These effects have been studied on 20 volunteers under different experimental circumstances. The results of these measurements are partially in line with earlier findings reported in the literature. New information is found for the dependence of the PNS threshold level as a function of the rise time of the gradient waveform. The PNS threshold level, expressed in terms of dB/dt, is found to be proportional with t^?05, where t is the switch time for the gradients. Indications are found that |B|, the modulus of the gradient vector field, is more closely related to the PNS threshold level than B_z, the imaging component of the gradient field. From the experiments, it is furthermore concluded that only for the imaging protocols characterized by the application of long bipolar repetitive gradient pulse trains, such as echo-planar imaging, PNS is expected at the reported threshold levels. For the protocols based on spin echo, turbo spin echo, inversion recovery, fast field echo, etc., characterized by shorter gradient pulse trains, the threshold levels are expected to be much higher.     

Autologous whole plasma fibrin gel. Intraoperative procurement.

Fibrin glue is a relatively recent addition to the armamentarium of hemostatic agents for surgical use. Its efficacy has been repeatedly demonstrated in almost all surgical disciplines and subspecialties. Its use in the United States has been limited because of the risk of viral transmission associated with the use of human plasma. Previous authors have described techniques that limit this risk, but they are frequently impractical, expensive, or cumbersome. We describe the use of patients' own fresh plasma to make fibrin gel at the operative field. It provided hemostasis at least as good as that from heterologous plasma glue in 40 cardiac surgical patients. Autologous whole plasma fibrin gel is inexpensive and safe and eliminates the risk of viral transmission associated with glue derived from heterologous donor plasma.     

Recurrence of nephrocalcinosis after renal transplantation in an adult patient with primary hyperoxaluria type I

The medical history of a 42-year-old patient with primary hyperoxaluria type I is presented. Primary hyperoxaluria was suspected after renal transplantation, when oxalate deposits were found in a biopsy of the kidney graft. Diagnosis of type I hyperoxaluria was confirmed by the finding that significantly increased amounts of glycolic acid and oxalic acid were excreted. Treatment of the patient with 500 mg pyridoxine daily resulted in a decrease of the excretion of oxalate to normal values.     

Validity of the beck depression inventory,hospital anxiety and depression scale,SCL-90, and hamilton depression rating scale as screening instruments for depression in stroke patients

Most instruments used to assess poststroke depression have never been specifically validated in stroke patients. This study evaluated the depression screening abilities of three questionnaires and one observer-rated scale in 202 consecutive patients 1 month after they experienced their first-ever ischemic stroke. At their respective optimum cutoff values, the sensitivity of the self-rated scales varied between 80% and 90%, while the specificity was about 60%. For the observer-rated scale (Hamilton Depression Rating Scale), sensitivity was 78.1%, and specificity was 74.6%. The instruments clearly performed better in men than in women. Despite this difference, it was concluded that all scales were acceptable screening instruments for poststroke depression.     

Muscle lactate transport studied in sarcolemmal giant vesicles: dependence on fibre type and age.

Lactate transport was studied in sarcolemmal giant vesicles obtained from rat or rabbit skeletal muscle. With this technique it is possible to obtain quantitative information on sarcolemmal transport characteristics. In equilibrium exchange experiments with 10, 30 and 60 mM lactate, vesicles from 'red' rat muscles had a 50% higher lactate transport capacity than vesicles from 'white' muscles. Giant vesicles made from rabbit red muscles had a 39% higher lactate transport capacity than vesicles from white muscles. These differences probably reflect a different number of lactate transporters, whereas the lactate affinity in red and white muscles are identical. Lactate transport capacity decreased with age. Sarcolemmal giant vesicles made from 22-month-old rats had a 28% lower transport capacity than vesicles from 2-month old rats. In absolute terms, the initial exchange flux with 30 mM lactate was 92 and 127 pmol cm-2 sec-1 for old and young rats, respectively. In supplementary studies in which microelectrode measurements were made in single mouse muscle fibers, it was shown that the cellular acidification rate due to lactate incubation, was 38% lower in fibres from 18-month old mice than in fibres from 2-month old mice.     

Assessing future trends in indoor air quality

Several national and international health organizations have derived concentration levels below which adverse effects on men are not expected or levels below which the excess risk for individuals is less than a specified value. For every priority pollutant indoor concentrations below this limit are considered "healthy." The percentage of Dutch homes exceeding such a limit is taken as a measure of indoor air quality for that component. The present and future indoor air quality of the Dutch housing stock is described for fourteen air pollutants. The highest percentages are scored by radon, environmental tobacco smoke, nitrogen dioxide from unvented combustion, and the potential presence of housedust mite and mould allergen in damp houses. Although the trend for all priority pollutants is downward the most serious ones remain high in the coming decades if no additional measures will be instituted.