The acquisition of skilled motor performance: fast and slow experience-driven changes in primary motor cortex

Behavioral and neurophysiological studies suggest that skill learning can be mediated by discrete, experience-driven changes within specific neural representations subserving the performance of the trained task. We have shown that a few minutes of daily practice on a sequential finger opposition task induced large, incremental performance gains over a few weeks of training. These gains did not generalize to the contralateral hand nor to a matched sequence of identical component movements, suggesting that a lateralized representation of the learned sequence of movements evolved through practice. This interpretation was supported by functional MRI data showing that a more extensive representation of the trained sequence emerged in primary motor cortex after 3 weeks of training. The imaging data, however, also indicated important changes occurring in primary motor cortex during the initial scanning sessions, which we proposed may reflect the setting up of a task-specific motor processing routine. Here we provide behavioral and functional MRI data on experience-dependent changes induced by a limited amount of repetitions within the first imaging session. We show that this limited training experience can be sufficient to trigger performance gains that require time to become evident. We propose that skilled motor performance is acquired in several stages: "fast" learning, an initial, within-session improvement phase, followed by a period of consolidation of several hours duration, and then "slow" learning, consisting of delayed, incremental gains in performance emerging after continued practice. This time course may reflect basic mechanisms of neuronal plasticity in the adult brain that subserve the acquisition and retention of many different skills.

Acute life-threatening toxocaral tamponade

An unusual case of life-threatening visceral larva migrans (toxocariasis) is reported herein. The patient was admitted with acute dyspnea and bilateral pleural effusion; rapidly pericardial tamponade developed. Blood and body fluid eosinophilia were elevated. Extensive investigations revealed no malignant process or vasculitis, but Toxocara infection was confirmed by rising specific antibody titers. The high seroprevalence of Toxocara antibodies, particularly in children, suggests that a diagnosis of visceral larva migrans should be considered before a diagnosis of systemic hypereosinophilic syndrome even when clinical presentation is unusual. Prophylaxis against this widespread polymorphic zoonotic infection is desirable in view of the potentially dramatic consequences of infestation.

[Measles, mumps and rubella vaccination status of school beginners in Munich]

A cross-sectional study was performed on all of 10029 school-beginners in Munich in 1994 to investigate the vaccination status of measles, mumps and rubella immunisation. The objective of the study was to determine socio-demographic and psychological factors affecting the MMR vaccination rate. Data were received from 81.8% of all 10029 school-beginners. The vaccination rate was 86.1% for measles, 84.5% for mumps and 72.9% for rubella (missing values not included). Low overall vaccination rate was found in not first-born children, children of parents with non-german nationality, in children of parents with a low socio-economic status, in children accompanied by a working parent, and in children accompanied by a smoking parent. Children without any denomination also showed a lower vaccination rate. Girls had a higher vaccination rate for rubella than boys. A higher overall vaccination rate for MMR was associated with parents considering these infections to have a high impact for people's health. Vice versa children of parents considering adverse effects of vaccination against MMR as an important impact on health had significant lower vaccination rate. The results of a multiple logistic regression model showed two factors significantly affecting the MMR vaccination rate: Physician's recommendation and individual attitude towards medicine seem to have the most important influence on decision making for or against vaccination. In conclusion MMR vaccination strategies have to be improved. New ways such as, no vaccination--no school's should be considered for Germany.

Accuracy of single-voxel proton MR spectroscopy in distinguishing neoplastic from nonneoplastic brain lesions

PURPOSE

To measure the accuracy of single-voxel, image-guided proton MR spectroscopy in distinguishing normal from abnormal brain tissue and neoplastic from nonneoplastic brain disease.

METHODS

MR spectroscopy was performed at 0.5 T with the point-resolved spectroscopic pulse sequence and conventional postprocessing techniques. Subjects consisted of a consecutive series of patients with suspected brain neoplasms or recurrent neoplasia and 10 healthy adult volunteers. Fifty-five lesions in 53 patients with subsequently verified final diagnoses were included. Spectra were interpreted qualitatively by visual inspection by nonblinded readers (prospectively) with the benefit of prior clinical data and imaging studies, and by blinded readers (retrospectively). The nonblinded readers interpreted the spectra as diagnostic or not, and, if diagnostic, as neoplastic or nonneoplastic. The blinded readers classified the spectra as diagnostic or not, and, if diagnostic, as normal or abnormal and as neoplastic or nonneoplastic (when abnormal). The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated from blinded and nonblinded MR spectroscopy interpretations. A receiver operator characteristic (ROC) curve analysis was performed on blinded MR spectroscopy interpretations.

RESULTS

The diagnostic accuracy averaged across four blinded readers in differentiating patients from control subjects was .96, while the area under the aggregate (pooled interpretations) ROC curve approached unity. Accuracy in the nonblinded and blinded discrimination of neoplastic from nonneoplastic disease was .96 and .83, respectively. The area under the aggregate ROC curve in the blinded discrimination of neoplasm from nonneoplasm was .89.

CONCLUSIONS

Image-guided proton spectra obtained at 0.5 T from patients with suspected neoplasia can be distinguished from spectra in healthy control subjects, and neoplastic spectra can be distinguished from nonneoplastic spectra with a high degree of diagnostic accuracy.

Role of technetium-99m sestamibi scintimammography and contrast-enhanced magnetic resonance imaging for the evaluation of indeterminate mammograms

This study evaluated and compared technetium-99m sestamibi scintimammography (SMM) and breast magnetic resonance imaging (MRI) results in patients with indeterminate mammograms to determine whether either technique can improve the sensitivity and specificity for the diagnosis of breast carcinoma. From 123 consecutive patients who underwent physical examination, mammography, SMM, and histopathologic confirmation, a subgroup of 82 patients presenting with indeterminate mammograms was studied. Sixty-eight patients underwent contrast-enhanced MRI. SMM results were scored on the basis of the intensity and pattern of sestamibi uptake. MRI images were scored on the basis of signal intensity increase after administration of contrast material as well as the enhancement pattern and speed of gadolinium uptake. The results obtained with the two techniques were compared and related to the final histopathologic diagnoses. Considering indeterminate findings as positive, the sensitivity of SMM was 79% and the specificity, 70%. MRI displayed a sensitivity of 84% and a specificity of 49%. When indeterminate results were considered negative, the sensitivity and specificity of SMM were 62% and 83%, respectively. MRI revealed a sensitivity and specificity of 56% and 79%, respectively. The calculated sensitivities and specificities demonstrate the diagnostic limitations of both SMM and MRI in the evaluation of patients with indeterminate mammographic findings. Due to the higher specificity, SMM may be the preferred modality in the evaluation of selected patients with breast abnormalities.

Stimulation by enkephalins of D-glucose absorption in rabbit ileum

In intact tissue, DAGO ([D-Ala2, MePhe4, Gly-ol5]enkephalin; 10(-5) M; mu-ligand; addition on the serosal side) stimulated D-glucose absorption and D-glucose-dependent variations in short-circuit current (delta Isc,glu); naloxone (10(-6) M) antagonized these effects. DADLE ([D-Ala2, D-Leu5]enkephalin, mainly a delta-ligand; 10(-5) M) and (pCl-Phe4)-DPDPE ([D-pen2, p-chloro-Phe4, D-Pen5]enkephalin, a more selective delta-ligand; 10(-5) M) did not significantly stimulate delta Isc,glu (addition on the serosal side). In the absence of the muscularis and myenteric plexus or using intact tissue treated with tetrodotoxin (TTX; 3 x 10(-7) M), DAGO was unable to increase delta Isc,glu. Addition of DAGO to the mucosal side did not induce any variations in delta Isc,glu. In conclusion, DAGO is able to increase D-glucose absorption by interacting with mu-receptors located in the myenteric plexus.

Two-dimensional electrophoretic analysis of vesicular and micellar proteins of gallbladder bile

Proteins associated with lipid vesicles or mixed micelles of human gallbladder bile were separated by Sepharose-2B gel filtration chromatography followed by protein concentration and delipidation. After two-dimensional polyacrylamide gel electrophoresis and silver staining up to 59 and 471 polypeptide spots were counted in vesicular and micellar fractions, respectively. As major components the plasma proteins transferrin, albumin, alpha-fibrinogen, beta-fibrinogen, gamma-immunoglobulin G, immunoglobulin light chains, alpha-1 antitrypsin and haptoglobin alpha-2 chain were identified in the lipid vesicles by comparison with human protein reference maps. However, most biliary proteins including the anionic polypeptide fraction are associated with mixed micelles. The pathophysiological significance of these proteins associated with lipids needs to be investigated further.

Biliary mucin secreted by cultured human gallbladder epithelial cells carries the epitope of CA 19-9

Serum CA 19-9 is increased in patients with different gastrointestinal malignancies. Unfortunately, CA 19-9 is also detected in high concentrations in normal bile causing unspecific serum elevations during inflammatory disease of the biliary tract and cholestasis. In order to identify the source of CA 19-9 in bile, the capacity of cultured human gallbladder epithelial cells (HGBEC) to secrete CA 19-9 was investigated. Cells were harvested from gallbladders removed by cholecystectomy and cultured for up to 14 days in collagen I coated 24-well culture dishes. CA 19-9 was measured in the culture medium by a solid-phase CA 19-9 EIA (Boehringer). In addition, culture medium was separated by Sepharose 4B-Cl, Concanavalin-A (Con-A) and CA 19-9 affinity chromatography. Significant CA 19-9 activity was measured in the culture medium after a 24 hour incubation period. Following separation of the culture medium by Sepharose 4B-Cl and Con-A affinity chromatography, 90% of the CA 19-9 activity was recovered in the exclusion volume (> 2000 kDa) from which 90% were identified as Con-A negative. A close correlation was found between CA 19-9 and concentrations of mucin purified from human gallbladder bile. Furthermore, CA 19-9 affinity chromatography selectively extracted mucins from the culture medium of HGBEC. Finally, addition of the mucin secretagogue bethanechol (6 mM) to the culture medium increased CA 19-9 activity in the medium. In conclusion, normal HGBEC secrete mucins carrying the epitope of CA 19-9. During inflammatory biliary disease unspecific elevation of CA 19-9 in serum may reflect both inflammatory hypersecretion and leakage of biliary mucins into serum.

[Comparison of efficacy and tolerability of a thrombolytic treatment with rt-PA in acute massive pulmonary embolism in the elderly and patients under 75 years of age]

BACKGROUND

Pulmonary embolism often occurs in elderly patients. However, clinical presentation and treatment of massive pulmonary embolism (PE) in the elderly have not been extensively investigated. We report the results of rt-PA bolus infusion in patients aged 75 years or more suffering from massive PE.

METHODS

Fifty-four adult patients referred to our institution with symptoms suggestive of massive PE were included in a therapeutic trial of single-chain rt-PA. Patients with a Miller angiographic score of at least 20/34 were considered for entry into the study. Patients were divided into two groups according to their age. Clinical presentation at admission, resolution of scintigraphic vascular obstruction, death rate, hemorrhagic complications, recurrent pulmonary embolism and long-term follow-up were compared between both groups.

RESULTS

Twenty-eight patients were less than 75 years old and 26 patients were aged 75 years or more. Clinical symptoms at admission were similar in both groups. The mean absolute improvement in the lung scan perfusion defect, the rate of major bleeding, and the long-term evolution were not statistically different between older and younger patients.

CONCLUSION

Clinical presentation and tolerance of massive PE did not differ between elderly and non-elderly patients. Old age should not preclude thrombolytic therapy in massive PE, provided there are no other contraindications for thrombolytic treatment.

Clonal expansion and decreased occurrence of peripheral blood gamma delta T cells of the V delta 2J delta 3 lineage in multiple sclerosis patients

gamma delta T cells are implicated in autoimmune diseases but their precise function remains unclear. In multiple sclerosis (MS) brain tissue, gamma delta T cells co-localize with heat shock protein (hsp)65+ oligodendrocytes and are oligoclonally restricted in the V delta 2J delta 3 lineage. To investigate the homing properties and the degree of heterogeneity of V delta 2J delta 3+ gamma delta T cells in MS, peripheral blood lymphocytes (PBL) from 34 MS patients, 42 controls (14 autoimmune control patients, 28 healthy volunteers), and 11 lymphatic tissues of MS patients and controls were studied by RT-PCR and sequencing. V delta 2J delta 3 TCR rearrangement was detected in 27 out of 28 healthy controls, and was significantly less frequent in MS patients (24 out of 34) and autoimmune control patients (seven out of 14). It was present only in five out of 11 tissue specimens, none of them from MS patients. Direct sequencing and cloning/automated sequencing of the V delta 2J delta 3 PCR products indicated heterogeneity in healthy controls and oligoclonality in MS patients, but also in autoimmune control patients. Differences between MS patients and healthy controls were more accentuated in exacerbating hospitalized patients than in clinically stable outpatients participating in a clinical trial. Only one V delta 2J delta 3 sequence of a total of 85 different sequences obtained was shared between two MS patients. Taken together, evidence for clonal expansion of V delta 2J delta 3+ gamma delta T cells was found in PBL of MS patients. This T cell subset, previously shown to be present in 100% of chronic-active MS plaques, might home to the CNS in MS, resulting in its under-representation in the blood.

The effect of treating herpes zoster with oral acyclovir in preventing postherpetic neuralgia. A meta-analysis

BACKGROUND

Herpes zoster is a common affliction in older patients, with up to 15% experiencing some residual pain in the distribution of the rash several months after healing. Despite numerous randomized clinical trials, the effect of treating herpes zoster with oral acyclovir in preventing postherpetic neuralgia remains uncertain because of conflicting results.

METHODS

Meta-analysis of published randomized clinical trials on the use of acyclovir to prevent postherpetic neuralgia using the fixed-effects model of Peto.

RESULTS

Thirty clinical trials of treatment with oral acyclovir in immunocompetent adults were identified. After excluding studies with duplicate data, suboptimal and topical dosing, non-placebo-controlled or nonrandomized designs, and those using intravenous acyclovir, 5 trials were found to be homogeneous and were combined for analysis. From these trials, the summary odds ratio for the incidence of "any pain" in the distribution of rash at 6 months in adults treated with acyclovir was 0.54 (95% confidence interval, 0.36-0.81).

CONCLUSION

Treatment of herpes zoster with 800 mg/d of oral acyclovir within 72 hours of rash onset may reduce the incidence of residual pain at 6 months by 46% in immunocompetent adults.

S-carbocysteine-lysine salt monohydrate and cAMP cause non-additive activation of the cystic fibrosis transmembrane regulator channel in human respiratory epithelium

S-Carbocysteine-lysine salt monohydrate (S-CMC-Lys) has been shown to open a Cl- channel in the trachea, thus aiding fluid secretion. The aim of this study was to characterize the channel and the action mechanism on a culture line of human respiratory epithelial cells. The patch-clamp technique (in cell-attached or inside-out configuration) and conventional micro-electrodes were used. The activity and density of a cAMP-dependent Cl- channel, identical to the cystic fibrosis transmembrane regulator (CFTR) channel, proved to be maximally stimulated by 100 microM S-CMC-Lys present in the cAMP-free cell incubation medium for 240-290 min (cell-attached configuration). Subsequent addition of cAMP to the medium did not determine any further activation. S-CMC-Lys acted mostly indirectly as, when placed in direct contact with a membrane patch, activation of the CFTR channel was nil (cytoplasmic side) or limited (external side).

[Current indications of low-molecular-weight heparins]

Low-molecular-weight heparins (LMWH) have different properties than non-fractionated heparins. Bioavailability is better after subcutaneous administration and a longer halflife allows a single daily injection. Efficacy is equivalent for postoperative thromboembolism prophylaxis for all types of surgery. In most reports, low-molecular-weight heparins are more effective than non fractionated heparin and lead to fewer episodes of hemorrhage and thrombocytopenia. For treatment of deep vein thrombosis, low-molecular-weight heparins are as effective as non-fractionated heparins after two, or even one, daily injection without hemostasis tests. Other on-going studies are evaluating LMWH indications in pulmonary embolism, artery disease, pregnancy or other medical conditions.

Intrapericardial fibrinolysis: a useful treatment in the management of purulent pericarditis

Since the introduction of antibiotics into clinical practice, purulent pericarditis has become a rare disease. The major complication of the standard management for this condition is constrictive pericarditis. We report two cases of purulent pericarditis in which intrapericardial fibrinolysis was performed in order to minimize this complication. The first case was a 38-year-old man admitted to our intensive care unit (ICU) for management of constrictive pericarditis complicating purulent pericarditis diagnosed 17 days previously. The patient was treated with four intrapericardial injections of streptokinase (250,000 IU each). Fluid drainage and cardiac output were improved. No change in clotting parameters was noted. Pericardiectomy and esophagectomy were then performed for a diagnosis of esophageal neoplasm. The postoperative course was uneventful. The second case was a 16-year-old boy admitted with loss of consciousness due to cardiac tamponade. Percutaneous pericardiocentesis drained 900 ml of cloudy fluid. Two intrapericardial injections were performed (day 1 and day 5) without any complication. Pericardial drainage was withdrawn on day 13 and the patient was discharged from ICU on the same day. Six months later, there was no evidence of constrictive pericarditis. Intrapericardial fibrinolysis appears to be safe and effective when prescribed rapidly in the course of purulent pericarditis.