L-arginine induces relaxation of small mesenteric arteries from endotoxin-treated rats.

The effect of arginine (Arg) was studied on norepinephrine- (1 microM) precontracted small mesenteric arteries removed from rats treated with E. coli lipopolysaccharide (LPS). The addition of L- (but not D-) Arg (1 mM) relaxed, within 3 min, the small mesenteric arteries from LPS-treated but not from control rats, the maximal relaxation (65.3 +/- 11%) being reached with less than 100 microM L-Arg. NG-Nitro-L-arginine methyl ester (1 mM) and methylene blue (10 microM) restored contractions to the level reached before addition of L-Arg. These results show that LPS induces the production of an L-Arg-derived, nitric oxide-like, relaxing factor in small mesenteric arteries.     

Improved anchorage in osteoporotic vertebrae with new implant designs.

The goal of our study was to evaluate two newly developed implant designs and their behavior in terms of subsidence in lumbar vertebral bodies under cyclic loading. The new implants were evaluated in two different configurations (two small prototypes vs. one large prototype with similar load-bearing area) in comparison to a conventional screw-based implant (MACS TL). A pool of 13 spines with a total of 65 vertebrae was used to establish five testing groups of similar bone mineral density (BMD) distribution with eight lumbar vertebrae each. In additional to BMD assessment via dual-energy X-ray absorptiometry, cancellous BMD and structural parameters were determined using a new generation in vivo 3D-pQCT. The specimens were loaded sinusoidally in force control at 1 Hz for 1000 cycles at three load levels (100, 200, and 400 N). A survival analysis using the number of cycles until failure (Cox regression with covariates) was applied to reveal differences between implant groups. All new prototype configurations except the large cylinder survived significantly longer than the control group. The number of cycles until failure was significantly correlated with the structural parameter Tb.Sp. and similarly with the cancellous BMD for three of five implants. In both large prototypes the cycle number until failure significantly correlated with the preoperative distance to the upper endplates. Although the direct relationship between bone structure or density and mechanical breakage behavior cannot be conclusively proven, all the prototypes adapted for poor bone structure performed better than the comparable conventional implant.     

Cardiac atrophy in women following bed rest

Both chronic microgravity exposure and long‐duration bed rest induce cardiac atrophy, which leads to reduced standing stroke volume and orthostatic intolerance. However, despite the fact that women appear to be more susceptible to post‐spaceflight presyncope and orthostatic hypotension than male astronauts, most previous high‐resolution studies of cardiac morphology following microgravity have been performed only in men. Because female athletes have less physiological hypertrophy than male athletes, we reasoned that they also might have altered physiological cardiac atrophy after bed rest. Magnetic resonance imaging was performed in 24 healthy young women (32.1±4 years) to measure left ventricular (LV) and right ventricular (RV) mass, volumes, and morphology accurately before and after 60 days of 6° head‐down tilt (HDT) bed rest. Subjects were matched and then randomly assigned to sedentary bed rest (controls, n=8) or two treatment groups consisting of (1) exercise training using supine treadmill running within lower body negative pressure plus resistive training (n=8), or (2) protein (0.45 g/kg/day increase) plus branched‐chain amino acid (BCAA) (7.2 g/day) supplementation (n=8). After sedentary bed rest without nutritional supplementation, there were significant reductions in LV (96±26–77±25 mL; P=0.03) and RV volumes (104±33–86±25 mL; P=0.02), LV (2.2±0.2–2.0±0.2 g/kg; P=0.003) and RV masses (0.8±0.1–0.6±0.1 g/kg; P<0.001), and the length of the major axis of the LV (90±6–84±7 mm. P<0.001), similar to what has been observed previously in men (8.0%; Perhonen M.A., Franco F., Lane L.D., Buckey J.C., Blomqvist Zerwekh J.E., Peshock R.M., Weatherall P.T., Levine B.D. J Appl Physiol 2001: 91: 645–653). In contrast, there were no significant reductions in LV or RV volumes in the exercise‐trained group, and the length of the major axis was preserved. Moreover, there were significant increases in LV (1.9±0.4–2.3±0.3 g/kg; P<0.001) and RV masses (0.7±0.1–0.8±0.2 g/kg; P=0.002), as well as mean wall thickness (9±2–11±1 mm; P=0.02). The interaction between sedentary and exercise LV and RV masses was highly significant (P<0.0001). Protein and BCAA supplementation led to an intermediate phenotype with no change in LV or RV mass after bed rest, but there remained a significant reduction in LV volume (103±14–80±16 mL; P=0.02) and major‐axis length (91±5–88±7 mm; P=0.003). All subjects lost an equivalent amount of body mass (3.4±0.2 kg control; 3.1±0.04 kg exercise; 2.8±0.1 kg protein). Cardiac atrophy occurs in women similar to men following sedentary 60 days HDT bed rest. However, exercise training and, to a lesser extent, protein supplementation may be potential countermeasures to the cardiac atrophy associated with chronic unloading conditions such as in spaceflight and prolonged bed rest.     

Alteration of visual evoked potentials and electroretinograms in Parkinson's disease

A group of 24 patients with Parkinson's disease (PD) with normal fundi and normal visual acuities was examined electrophysiologically. Checkerboard reversal VEPs and ERGs (P-ERGs) at various contrast levels as well as photopic and scotopic luminance ERGs were recorded and compared with an age-matched group of controls. Earlier reported latency increases of the VEPs of the patients were confirmed for patterns of high contrast only. Scotopic and photopic luminance ERGs of the patients showed normal latencies, but at all light intensities the amplitudes of the scotopic and photopic b wave, as well as the amplitudes of the photopic a waves, were significantly reduced, P-ERG amplitudes were reduced at 50% contrast. Identical results were obtained in patients under dopaminergic treatment (n = 17) and in patients who did not receive any treatment (n = 7). These results suggest that alterations occur already at the retinal level where dopamine receptors have been found. Thus the reported changes of the VEP are not caused by the visual cortex alone.     

Antigenic structure of the hexacosapeptide melittin: evidence for three determinants, one with a helical conformation.

ELISA-based epitope analysis was performed using rabbit polyclonal antisera against melittin. Antigenic sites were found at the C-terminus, in the middle section and within the N-terminal helix. Antibodies against the helical segment could discriminate between two faces of the amphiphilic helix. The antigenic sites include the bulk of the melittin hexacosapeptide, which is synonymous with a very high epitope density.     

Sonographic and computerized tomography study of congenital choledochal cyst

In the neonatal period ultrasound and hepatobiliary functional scintigraphy are used to diagnose choledochal cysts. Initial sonography demonstrates hepatobiliary anatomy, hepatobiliary function is assessed by subsequent scintigraphy. The diagnosis can be confirmed by additional computed tomography as shown in this case report.     

Gastric outlet obstruction after long-term prostaglandin administration mimicking hypertrophic pyloric stenosis.

Prostaglandin E1 (PGE1) is widely used in neonates with cyanotic congenital heart disease who depend on the patency of the ductus arteriosus for oxygenation. Side effects of prostaglandin therapy are common and include respiratory depression, generalized flushing, and cardiovascular and neurological effects. Little is known about the complex effects on the gastrointestinal tract. We report on an infant with gastric outlet obstruction after long-term prostaglandin administration. At the age of 1 month, feeding problems developed with projectile vomiting. Ultrasonography showed progressive elongation of the antropyloric channel without wall thickening, which was causing gastric outlet obstruction. Three days after cardiac surgery and cessation of prostaglandin therapy, the infant fed normally and rapidly gained weight. The clinical signs in such patients can mimic hypertrophic pyloric stenosis. Therefore, the sonographic findings should not be confused with pyloric wall thickening to avoid a false diagnosis and unnecessary surgery. The symptoms diminish with cessation of the prostaglandin therapy after a corrective cardiac operation.     

Intraabdominal pressures during natural activities in patients treated with continuous ambulatory peritoneal dialysis

Intraabdominal pressures were measured during natural activities in 6 men, age 24-62 years, treated with continuous ambulatory peritoneal dialysis. The pressures were measured with a pressure transducer secured at the level of the umbilicus in the supine, sitting, and upright positions with 0-3 liters intraperitoneal fluid during talking, coughing, straining, changing position, walking, jogging, exercycling, jumping and weight lifting. Coughing and straining generated the highest intraabdominal pressures in every position. The pressures with weight lifting were proportional to the magnitude of the weight lifted up to 50 lbs, but were lower than those during coughing and straining. The pressures were generally higher with greater intraabdominal fluid volumes, especially with jumping and coughing. Exercycling was associated with lower intraabdominal pressure than was jogging, and the pressures were only minimally influenced by intraperitoneal fluid volumes. The results of this study can be used as a guide in establishing preventive measures in patients with intraperitoneal fluid to decrease complication rates related to raised intraabdominal pressures such as dialysate leaks, hernias and hemorrhoids.