Uroscopy in the 21st century: high-field NMR spectroscopy

From the experiments described, it can be seen that there are different research approaches that can be taken and these are summarized in Table 1. Whereas much scientific research is principally hypothesis led, there remains, nevertheless, an important place for exploratory research. High resolution NMR can measure, directly and simultaneously, a wide range of endogenous metabolites in biological fluids and has the unique capability of providing structural information on the metabolites detected. It has proved to be a powerful research tool with which to study inherited metabolic diseases, renal disease, drug metabolism, and toxicity, and can be used to monitor the effects of drug therapy. For instance, by using a library of experimental toxins one can map the metabolic profile of site-specific nephron injury. With this approach in man one could eventually take an unknown disease such as Balkan nephropathy and predict the initial site of tubular injury, the mode of injury and therefore the kind of toxin capable of producing that injury. NMR spectroscopic techniques are still advancing rapidly, with ever increasing sensitivity and sophistication of NMR pulse sequences to enhance structural elucidation in complex mixtures. Given the advances in directly coupled HPLC-NMR and even HPLC-NMR-mass spectroscopy it is likely that these technologies in conjunction with pattern recognition will make major contribution to our understanding of renal processes and provide new diagnostic insights in the 21st century.      

Testosterone not associated with violent dreams or REM sleep behavior disorder in men with Parkinson's.

We examined the relationship between testosterone levels, violent dreams, and REM sleep behavior disorder (RBD) in 31 men with Parkinson's disease (PD): 12 with clinical RBD and 19 without. All PD patients with clinical RBD experienced violent dreams, but none of the 19 non-RBD patients reported violent dreams. While dream content appears to be more aggressive in PD patients with clinical RBD, the presence of violent dreams or clinical RBD is not associated with testosterone levels in men with PD.     

Activation of guinea pig eosinophil respiratory burst by leukotriene B4: role of protein kinase C

Leukotriene B4 (LTB4) and the protein kinase C activator, 4-beta-phorbol dibutyrate (PDBu), both induced a pronounced and concentration-dependent stimulation of hydrogen peroxide (H2O2) generation by purified guinea pig peritoneal eosinophils in the concentration range 1 nM-1 microM. The LTB4 response was inhibited competitively by the specific LTB4 receptor antagonist, U-75302, with a KB of 25 nM, while the concentration-response curves for both stimuli were shifted rightwards (3.8-fold and 2.8-fold for LTB4 and PDBu, respectively) by the competitive protein kinase C inhibitor, 1-O-hexadecyl-2-O-methylglycerol at a concentration of 300 microM. LTB4 appears, therefore, to induce respiratory burst in eosinophils via a receptor-mediated mechanism involving protein kinase C.     

Transient ischemic attacks resulting from carotid duplex imaging

Duplex imaging has been widely embraced as a safe and an accurate means of interrogating the extracranial carotid vessels. One reason for this is its appearance as a risk-free diagnostic tool. We report the cases of two patients in whom transient ischemic attacks developed during duplex imaging--attacks that began soon after application of the ultrasound transducer to the cervical region, were identical to prior attacks, and ceased within seconds of removal of the transducer from the neck. The underlying cause of this complication is discussed as is its proper management.     

Atrial fibrillation after stroke in the elderly

To examine the relationship between atrial fibrillation and mortality after stroke, we studied 186 men and 167 women from the Waikato Stroke Registry whose mean age was 75.2 +/- 7.5 years. Twenty-three percent (82 of 353) had atrial fibrillation or flutter on their admission electrocardiogram. This group differed significantly from that with sinus rhythm in three respects: 1) They were older (p less than 0.01); 2) they had more severe current stroke deficit as evidenced by lower limb power (p less than 0.05) and Mini-Mental State Score (p less than 0.001), higher incidence of homonomous hemianopia (p less than 0.05), and lower incidence of lacunar syndrome stroke (p less than 0.001); and 3) they had a significantly higher incidence of cardiomegaly and congestive heart failure (p less than 0.01). Functional outcome was insignificantly better in the group with sinus rhythm. During a mean follow-up period of 18 months, mortality was significantly higher in the group with atrial fibrillation (p = 0.001). Proportional hazards modeling, however, showed that the apparently poorer survival in those patients with atrial fibrillation could be explained by factors other than cardiac rhythm, such as age, Mini-Mental State Score, level of consciousness, and interstitial edema on admission chest radiograph. Thus, atrial fibrillation was not an independent predictor of survival after stroke.     

A not-so-basic case of metabolic alkalosis: an analysis featuring Leendert Paul and emphasizing Occam’s razor

A patient had the onset of a severe degree of metabolic alkalosis associated with a very large daily loss of diarrheal fluid. Because the expected acid-base disorder in this setting is metabolic acidosis, factors that could result in the markedly increased concentration of bicarbonate (HCO₃⁻) in plasma (P ₃) were sought. In our approach, there is an emphasis on electroneutrality, mass balance, a quantitative analysis, and the application of basic concepts in physiology at the bedside. We suggest that there were 3 major factors that could explain why the P ₃ was so high. First, a severe degree of extracellular fluid volume contraction was probably the most important factor that raised her P ₃. Second, there may have been an unusual way to have an electroneutral addition of HCO₃⁻ and removal of chloride ions from her extracellular fluid compartment. Third, the diarrheal fluid could have contained little HCO₃⁻ because of a down-regulated intestinal secretion of HCO₃⁻. This analysis challenges the traditional pathophysiology of metabolic alkalosis.