Loads applied tangential to a fingertip during an object restraint task can trigger short-latency as well as long-latency EMG responses in hand muscles

Electrical stimulation of the digital nerves can cause short- and long-latency increases in electromyographic activity (EMG) of the hand muscles, but mechanical stimulation of primarily tactile afferents in the digits generally evokes only a long-latency increase in EMG. To examine whether such stimuli can elicit short-latency reflex responses, we recorded EMG over the first dorsal interosseous muscle when subjects (n=13) used the tip of the right index finger to restrain a horizontally oriented plate from moving when very brisk tangential forces were applied in the distal direction. The plate was subjected to ramp-and-hold pulling loads at two intensities (a 1-N load applied at 32 N/s or a 2-N load applied at 64 N/s) at times unpredictable to the subjects (mean interval 2 s; trial duration 500 ms). The contact surface of the manipulandum was covered with rayon—a slippery material. For each load, EMG was averaged for 128 consecutive trials with reference to the ramp onset. In all subjects, an automatic increase in grip force was triggered by the loads applied at 32 N/s; the mean onset latency of the EMG response was 59.8±0.9 (mean ± SE) ms. In seven subjects (54%) this long-latency response was preceded by a weak short-latency excitation at 34.6±2.9 ms. With the loads applied at 64 N/s, the long-latency response occurred slightly earlier (58.9±1.7 ms) and, with one exception, all subjects generated a short-latency EMG response (34.9±1.3 ms). Despite the higher background grip force that subjects adopted during the stronger loads (4.9±0.3 N vs 2.5±0.2 N), the incidence of slips was higher—the manipulandum escaped from the grasp in 37±5% of trials with the 64 N/s ramps, but in only 18±4% with the 32-N/s ramps. The deformation of the fingertip caused by the tangential load, rather than incipient or overt slips, triggered the short-latency responses because such responses occurred even when the finger pad was fixed to the manipulandum with double-sided adhesive tape so that no slips occurred.     

Isodicentric 7p, idic(7)(q11.2), in acute myeloid leukemia associated with older age and favorable response to induction chemotherapy: a new clinical entity?

Three adult de novo acute myeloid leukemias (AML M1, M2, and M4) with an isochromosome 7p are presented. No additional abnormalities were detected by G-band and multicolor, using combined binary ratio labeling, fluorescence in situ hybridization (FISH) analyses, indicating that the i(7p) was the sole, i.e., the primary, chromosomal aberration. Although the patients were elderly--68, 72, and 78 years old--they all responded very well to chemotherapy, achieving complete remission lasting more than a year. Further FISH analyses, using painting, centromeric, as well as 7q11.2-specific YAC probes, revealed that the i(7p) contained two centromeres and that the breakpoints were located in 7q11.2. Thus, the abnormality should formally be designated idic(7)(q11.2). The detailed mapping disclosed a breakpoint heterogeneity, with the breaks in 7q11.2 varying among the cases, being at least 1,310 kb apart. Furthermore, the breakpoints also differed within one of the cases, being located on both the proximal and the distal side of the most centromeric probe used. Based on our three patients, as well as on a previously reported 82-year-old patient with AML M2 and idic(7)(q11) as the only chromosomal change, we suggest that this abnormality, as the sole anomaly, is associated with AML in elderly patients who display a good response to induction chemotherapy and, hence, have a favorable prognosis. Furthermore, the heterogeneous breakpoints in 7q11.2 suggest that the important functional outcome of the idic(7)(q11.2) is the genomic imbalance incurred, i.e., gain of 7p and loss of 7q material, rather than a rearrangement of a specific gene.     

Synthesis and characterization of monomethacrylate-functionalized self-organizing crown ether compounds

Synthesis and characterization of methacrylate-monofunctionalized crown ether compounds based on derivatives of 2-hydroxymethyl-1,4,7,10,13-pentaoxacyclopentadecane and 4′-hydroxymethyl-1,4,7,10,13-pentaoxabenzocyclopentadecane is described. By differential scanning calorimetry (DSC) and thermooptical analysis (TOA) it is shown that the synthesized compounds and their sodium triflate complexes exhibit columnar mesophases.     

Group A Streptococci from carriage and disease in Portugal: evolution of antimicrobial resistance and T antigenic types during 2000-2002

In this study, we analyzed the antimicrobial resistance properties and T antigenic types of 511 isolates collected in Lisbon district, Portugal, from throat swabs of healthy subjects (n=341), during 2000-2002 and from diverse infection sites (n=170) of outpatients and inpatients, during 1999-2002. Erythromycin resistance was higher in tonsillitis/pharyngitis (27.4%) and skin infection isolates (21.1%), than in carriage and invasive isolates (相似文献   

Control of grasp stability in humans under different frictional conditions during multidigit manipulation

Control of grasp stability under different frictional conditions has primarily been studied in manipulatory tasks involving two digits only. Recently we found that many of the principles for control of forces originally demonstrated for two-digit grasping also apply to various three-digit grasps. Here we examine the control of grasp stability in a multidigit task in which subjects used the tips of the thumb, index, and middle finger to lift an object. The grasp resembled those used when lifting a cylindrical object from above. The digits either all contacted the same surface material or one of the digits contacted a surface material that was more, or less, slippery than that contacted by the other two digits. The three-dimensional forces and torques applied by each digit and the contact positions were measured along with the position and orientation of the object. The distribution of forces among the digits strongly reflected constraints imposed by the geometric relationship between the object's center of mass and the contact surfaces. On top of this distribution, we observed changes in force coordination related to changes in the combination of surface materials. When all digits contacted the same surface material, the ratio between the normal force and tangential load (F(n):L ratio) was similar across digits and scaled to provide an adequate safety margin against slip. With different contact surfaces subjects adapted the F(n):L ratios at the individual digits to the local friction with only small influences by the friction at the other two digits. They accomplished this by scaling the normal forces similarly at all digits and changing the distribution of load among the digits. The surface combination did not, however, influence digit position, tangential torque, or object tilting systematically. The change in load distribution, rather, resulted from interplay between these factors, and the nature of this interplay varied between trials. That is, subjects achieved grasp stability with various combinations of fingertip actions and appeared to exploit the many degrees of freedom offered by the multidigit grasp. The results extend previous findings based on two-digit tasks to multidigit tasks by showing that subjects adjust fingertip forces at each digit to the local friction. Moreover, our findings suggest that subjects adapted the load distribution to the current frictional condition by regulating the normal forces to allow slips to occur early in the lift task, prior to object lift-off.     

Sex Differences in the Catecholamine Output of Children

Urinary excretion of catecholamines was studied in 240 normal, healthy children 12 years of age during a passive condition (film exposure) and an active condition (arithmetic test) at school. No sex differences in catecholamine excretion were found during the passive condition, whereas, during the work period, boys excreted significantly more adrenaline and noradrealine than girls. A comparison is made between catecholamine excretion levels of the children and adult subjects examined in other studies.     

Omalizumab and the immune system: an overview of preclinical and clinical data.

OBJECTIVE: This review discusses the role of immunoglobulin (Ig)E in allergic disease, inhibition of IgE with omalizumab, and the consequences of IgE inhibition (both clinically and in terms of the effect on the immune system). DATA SOURCES: Relevant publications obtained from a literature review. STUDY SELECTION: Relevant publications on IgE, allergic disease, and anti-IgE were critically evaluated. RESULTS: IgE plays a key role in allergic diseases such as allergic asthma and allergic rhinitis. Its role in healthy individuals is less well defined. Treatment of allergic asthma and rhinitis with omalizumab, a humanized monoclonal anti-IgE antibody, causes a marked reduction in circulating free IgE levels. This has been shown to reduce symptoms and decrease the need for other medication in patients with these allergic diseases. Anti-IgE treatment with omalizumab did not cause any of the complications that might, in theory, be expected to result from reduction in circulating free IgE, such as adverse effects upon the immune system or other body systems. CONCLUSIONS: The limited clinical data currently available suggest that this novel method of treatment for allergic asthma and rhinitis seems to be both effective and well tolerated in clinical use.     

Evidence for the involvement of the posterior parietal cortex in coordination of fingertip forces for grasp stability in manipulation

Grasp stability during object manipulation is achieved by the grip forces applied normal to the grasped surfaces increasing and decreasing in phase with increases and decreases of destabilizing load forces applied tangential to the grasped surfaces. This force coordination requires that the CNS anticipates the grip forces that match the requirements imposed by the self-generated load forces. Here, we use functional MRI (fMRI) to study neural correlates of the grip-load force coordination in a grip-load force task in which six healthy humans attempted to lift an immovable test object held between the tips of the right index finger and thumb. The recorded brain activity was compared with the brain activity obtained in two control tasks in which the same pair of digits generated forces with similar time courses and magnitudes; i.e., a grip force task where the subjects only pinched the object and did not apply load forces, and a load force task, in which the subjects applied vertical forces to the object without generating grip forces. Thus neither the load force task nor the grip force task involved coordinated grip-load forces, but together they involved the same grip force and load force output. We found that the grip-load force task was specifically associated with activation of a section of the right intraparietal cortex, which is the first evidence for involvement of the posterior parietal cortex in the sensorimotor control of coordinated grip and load forces in manipulation. We suggest that this area might represents a node in the network of cortical and subcortical regions that implement anticipatory control of fingertip forces for grasp stability.     

Neuropeptide changes in a primate model (Cebus apella) for tardive dyskinesia.

Tardive dyskinesia has been connected with regional reductions of GABA functions in the basal ganglia. In view of the possibility that peptides are involved in neuroleptic-induced dyskinesias substance P and dynorphin A levels were measured in the basal ganglia of the Cebus apella model for tardive dyskinesia. In addition, regional glutamate decarboxylase activities, dopamine, homovanillic acid and dihydroxyphenylacetic acid levels were monitored. A significant dyskinesia-related decrease in glutamate decarboxylase activity was found in the subthalamic nucleus, the medial segment of globus pallidus and the rostral part of substantia nigra in accordance with earlier findings. Cebus monkeys with an intact GABA system (neuroleptic-treated controls without dyskinesia) showed increased levels of substance P and homovanillic acid in the caudate nucleus. The changes were confined to the caudal part of the body of the caudate and the nucleus accumbens. On the other hand, the dyskinetic monkeys, with a defective GABA system, did not demonstrate a similar substance P rise in the caudate or nucleus accumbens, but showed a depression of homovanillic acid levels in the caudal part of the body of the caudate nucleus. Dynorphin A, dopamine and dihydroxyphenylacetic acid showed no dyskinesia-related changes. In conclusion, the difference in glutamate decarboxylase activity between animals developing dyskinetic symptoms vs those who did not, was reflected by regional changes in substance P and homovanillic acid levels.