Identification of four novel melanocortin 1 receptor (MC1R) gene variants in a Mediterranean population

The melanocortin 1 receptor (MC1R) gene is a major determinant of human pigmentation and specific allelic variants have been associated with red hair and sun sensitive skin types as well as increased skin cancer risk in Caucasian individuals. We screened for allelic variants the entire MC1R coding region of 100 unrelated individuals sampled from an Italian population who has darker pigmentary traits than populations analyzed to date. Twenty MC1R variants were identified, eighteen located at non-synonymous sites and two at synonymous sites. We report four novel MC1R allelic variants: C35Y (g.104G>A), V38M (g.112G>A), L44V (g.130C>G) and I120T (g.359T>C).     

Coordination of multiple muscles in two degree of freedom elbow movements

The present study quantifies electromyographic (EMG) magnitude, timing, and duration in one and two degree of freedom elbow movements involving combinations of flexion-extension and pronation-supination. The aim is to understand the organization of commands subserving motion in individual and multiple degrees of freedom. The muscles tested in this study fell into two categories with respect to agonist burst magnitude: those whose burst magnitude varied with motion in a second degree of freedom at the elbow, and those whose burst magnitude depended on motion in one degree of freedom only. In multiarticular muscles contributing to motion in two degrees of freedom at the elbow, we found that the magnitude of the agonist burst was greatest for movements in which a muscle acted as agonist in both degrees of freedom. The burst magnitudes for one degree of freedom movements were, in turn, greater than for movements in which the muscle was agonist in one degree of freedom and antagonist in the other. It was also found that, for movements in which a muscle acted as agonist in two degrees of freedom, the burst magnitude was, in the majority of cases, not different from the sum of the burst magnitudes in the component movements. When differences occurred, the burst magnitude for the combined movement was greater than the sum of the components. Other measures of EMG activity such as burst onset time and duration were not found to vary in a systematic manner with motion in these two degrees of freedom. It was also seen that several muscles which produced motion in one degree of freedom at the elbow, including triceps brachii (long head), triceps brachii (lateral head), and pronator quadratus displayed first agonist bursts whose magnitude did not vary with motion in a second degree of freedom. However, for the monoarticular elbow flexors brachialis and brachioradialis, agonist burst magnitude was affected by pronation or supination. Lastly, it was observed that during elbow movements in which muscles acted as agonist in one degree of freedom and antagonist in the other, the muscle activity often displayed both agonist and antagonist components in the same movement. It was found that, for pronator teres and biceps brachii, the timing of the bursts was such that there was activity in these muscles concurrent with activity in both pure agonists and pure antagonists. The empirical summation of EMG burst magnitudes and the presence in a single muscle of both agonist and antagonist bursts within a movement suggest that central commands associated with motion in individual degrees of freedom at the elbow may be superimposed to produce elbow movements in two degrees of freedom.     

Hand and joint paths during reaching movements with and without vision

 This study examines whether the kinematics of pointing movements are altered by the sensory systems used to select spatial targets and to guide movement. Hand and joint paths of visually guided reaching movements of human subjects were compared with two non-visual conditions where only proprioception was available: (1) movements of the same subjects with blindfolds, and (2) movements by congenitally blind subjects. While hand-path curvatures were overall quite small, sighted subjects wearing a blindfold showed a statistical increase in hand-path curvature compared with their visually guided movements. Blindfolded subjects also showed greater hand-path curvature than blind subjects. These increases in hand-path curvature for blindfolded subjects did not always lead to a decrease in joint-path curvature. While there were differences between blind subjects and sighted subjects using vision for some movement directions, there was no systematic difference between these two groups. The magnitude of joint-path curvature showed much greater variation than hand-path curvature across the movement directions. We found variation in joint-path curvature to be correlated to two factors, one spatial and one geometrical. For all subject groups, joint-path curvature tended to be smaller for sagittal-plane movements than for transverse or diagonal movements. As well, we found that the magnitude of joint-path curvature was also related to the relative motion at each joint. Joint-path curvature tended to increase when movements predominantly involved changes in shoulder angle and was minimal when movements predominantly involved elbow motion. The consistently small curvatures of hand trajectory across blind and sighted subjects emphasize the powerful tendency of the motor system to generate goal-directed reaching movements with relatively straight hand trajectories, even when deprived of visual feedback from very early in life. Received: 16 July 1997 / Accepted: 20 May 1998     

Transmural distribution of antioxidant defences and lipid peroxidation in the rabbit left ventricular myocardium

The left ventricular subendocardial and subepicardial layers of six perfused rabbit hearts were tested for enzymatic and non-enzymatic antioxidant defences and for lipid peroxidation. The subendocardium showed significantly lower catalase activity and contents of non-protein thiol compounds and vitamin E associated with a higher degree of lipid peroxidation. The activities of Cu,Zn- and Mn-superoxide dismutases, glutathione reductase, -glutamylcysteine synthetase and -glutamyl transpeptidase showed no significant transmural differences, and Se-independent glutathione peroxidase activity was not detectable in either layer. Comparable results were observed in another group of six unperfused rabbit hearts. In five H₂O₂-perfused rabbit hearts, lipid peroxidation was higher, and myocardial creatine phosphokinase activity lower, in the subendocarium than in the subepicardium. In this group, only the subendocardium had significantly higher lipid peroxidation levels than the control hearts. Thus, a lower antioxidant capacity and a greater oxidative stress are present in the rabbit subendocardium. These findings could provide insight into the problem of subendocardial vulnerability to free radical-mediated processes, such as occurs in ischaemia-reperfusion injury.     

Cholinergic responses in cloned human TE671/RD tumour cells

The cholinergic responses of the human tumour cell line TE671/RD were examined using digital Ca²⁺ imaging fluorescence microscopy and patch-clamp measurements. In response to stimulation of the muscarinic acetylcholine (ACh) receptor (mAChR), the intracellular concentration of Ca²⁺ ([Ca²⁺]_i) rose about two-fold, in parallel with inositol 1,4,5-trisphosphate accumulation, measured by chromatographic techniques. By contrast, there was no increment of [Ca²⁺]_i upon stimulation of the nicotinic ACh receptor (nAChR), nor after caffeine application. Electrophysiological experiments showed that TE671/RD cells lack functional voltage-activated Ca²⁺ channels. The stimulation of the nAChR induced transient whole-cell currents (I _ACh). Little or no current was detected in isotonic extracellular Ca²⁺, with Cs⁺ in the patch pipette. Cell pretreatment with muscarine reduced I _ACh by about 20%, without consistent modifications of current kinetics. Muscarine applied to the extra-patch membrane under the cell-attached configuration had no obvious effect on ACh-evoked unitary events. In conclusion, in human TE671/ RD cells, muscarinic stimulation increases [Ca²⁺]_i, while nicotinic stimulation does not. In addition, the nAChR exhibits peculiar ion permeability properties and is not functionally regulated by the breakdown of phosphoinositides.     

Anti-HIV effects of chloroquine: inhibition of viral particle glycosylation and synergism with protease inhibitors

OBJECTIVE: We tested the effects of chloroquine (CQ) on glycosylation of HIV particles and in combination with protease inhibitors (PIs) on HIV replication and on P-glycoprotein (P-gp)/multidrug resistance protein-1 (MRP1). DESIGN: CD4 cell lines were infected with laboratory strains and peripheral blood mononuclear cells were infected with primary isolates for evaluation of the anti-HIV effects. Peripheral blood lymphocytes were evaluated for of P-gp and MRP1 functions. METHODS: HIV replication was assessed by enzyme-linked immunosorbent assay. HIV glycosylation was measured by metabolic labeling of viral particles with [H] glucosamine. Synergism was tested using isobolograms. P-gp and MRP1 functions were assayed using rhodamine 123 (Rh123) and carboxyfluorescein (CF) efflux assays, respectively. RESULTS: CQ alone inhibited HIV replication and glycosylation in a dose-dependent manner. In combination with indinavir (IDV), ritonavir, or saquinavir (SQV), CQ had a synergistic effect at concentrations found in plasma of subjects receiving malaria prophylaxis. CQ decreased the 50% effective concentration of IDV in primary isolates from Africa and restored the response to IDV or SQV in 3 PI-resistant isolates. CQ increased the block of Rh123 and CF efflux activity exerted by PIs. CONCLUSION: The inhibitory effects of CQ on HIV glycosylation are associated with synergistic effects in combination with PIs. The CQ/PI combination exerts combined inhibitory effects on P-gp and MRP1 function.     

First evaluations of LPV/RTV (Kaletra) efficacy on HIV-positive patients treated with multiple drugs

At the current epidemic stage, characterized by the rise of antiretroviral drug resistance, it is necessary to administer to HIV-positive patients increasingly effective treatments. This is possible only by means of powerful drugs. In a retrospective study, the authors evaluate 78 patients: 76 pre-treated with multiple drugs and 2 na ves. The 78 patients received LPV/RTV, starting from the fourth 3-month period of 2000 until the first 3-month period of 2002. The average treatment duration was 6.5 ( 5.5) months; the median value 6 months. The efficacy of the LPV/RTV therapeutic regimen was evaluated by a cytofluorimetric count of CD4+ and determination of the HIV viral load. There were 14 drop-out patients (17.9%): 5 because of auto-suspension, 1 due to absence of clinical and virological efficacy, 5 due to side effects (3 hepatopathy, 1 allergy and 1 nausea); three patients were lost on follow-up. There were 64 (82.1%) patients on treatment. Forty patients responded (51.3%) and 13 (16.7%) had uncontrolled viraemia (over than 200 copies/ml). However, the treatment with LPV/RTV was not interrupted for these patients, because in the follow-up they showed an increase in CD4+ values. The authors conclude that the LPV/RTV combination confirms previous findings: it is a drug with a relatively low incidence of side effects, capable of powerful results even in the treatment of patients receiving multiple drugs and thus subjected to the risk of developing antiretroviral drug resistance.