Altered Mesenchymal Stem Cells Mechanotransduction from Oxidized Collagen: Morphological and Biophysical Observations

Extracellular matrix (ECM) provides various mechanical cues that are able to affect the self-renewal and differentiation of mesenchymal stem cells (MSC). Little is known, however, how these cues work in a pathological environment, such as acute oxidative stress. To better understand the behavior of human adipose tissue-derived MSC (ADMSC) in such conditions, we provide morphological and quantitative evidence for significantly altered early steps of mechanotransduction when adhering to oxidized collagen (Col-Oxi). These affect both focal adhesion (FA) formation and YAP/TAZ signaling events. Representative morphological images show that ADMSCs spread better within 2 h of adhesion on native collagen (Col), while they tended to round up on Col-Oxi. It also correlates with the lesser development of the actin cytoskeleton and FA formation, confirmed quantitatively by morphometric analysis using ImageJ. As shown by immunofluorescence analysis, oxidation also affected the ratio of cytosolic-to-nuclear YAP/TAZ activity, concentrating in the nucleus for Col while remaining in the cytosol for Col-Oxi, suggesting abrogated signal transduction. Comparative Atomic Force Microscopy (AFM) studies show that native collagen forms relatively coarse aggregates, much thinner with Col-Oxi, possibly reflecting its altered ability to aggregate. On the other hand, the corresponding Young's moduli were only slightly changed, so viscoelastic properties cannot explain the observed biological differences. However, the roughness of the protein layer decreased dramatically, from R_RMS equal to 27.95 ± 5.1 nm for Col to 5.51 ± 0.8 nm for Col-Oxi (p < 0.05), which dictates our conclusion that it is the most altered parameter in oxidation. Thus, it appears to be a predominantly topographic response that affects the mechanotransduction of ADMSCs by oxidized collagen.

PREVALENCE OF MTHFR GENE 677C>T POLYMORPHISM IN THE PATIENTS WITH PSORIASIS VULGARIS

The study aimed to investigate the relationship between carriage of 677C>T polymorphism in the gene of methylene tetrahydrofolate reductase (MTHFR) and plaque psoriasis in patients in Bulgaria. We examined the prevalence of MTHFR C677T genotype in patients with psoriasis, as well as the relationship of the polymorphism with disease severity. Our study covered63 patients with psoriasis and 98psoriasis-free control subjects from northern Bulgaria. MTHFR677C>T genotype was verified by the PCR-RFLP method. There was no significant difference between carriage of TT genotype among the patients and controls: 12.7% versus 10.8 %in controls, OR 1.203, (CI 95% 0465-3.175), p>0.05 respectively. There was a higher PASI score in patients, carriers of TT genotype of MTHFR polymorphism 677C>T than in non-carriers, 28.18versus 24.87 respectively, but not significant. Conclusion: Carriage of TT genotype of MTHFR polymorphism 677C>T was not associated with Psoriasis Vulgaris in the northern Bulgarian population when compared to healthy controls.

Development of a measure of collective efficacy within personal networks: A complement to self-efficacy in self-management support?

OBJECTIVE

To develop and evaluate the Collective Efficacy of Networks (CENS) questionnaire to measure perceived collective efficacy within personal social networks.

METHODS

A mixed methods approach was used, guided by theory and with extensive input from adults with long-term conditions who completed the initial questionnaire (n = 78) with test-retest assessed at 2 weeks (n = 68). A second sample (n = 85) completed a postal questionnaire including CENS, theoretically linked constructs (self-efficacy, social support) and health outcomes (loneliness, mental and physical health).

RESULTS

Principal components analysis demonstrated a two-factor structure with 12-items selected to represent Network responsiveness (8 items, Cronbach's alpha = 0.896) and Access to collective efficacy (4 items, Cronbach's alpha = .773). Good test-retest reliability was established for both subscales (r_icc = .793-.853). Network responsiveness was associated with self-efficacy (r = 342, p = . < 001) and social support (r = .407, p < .001) and predicted reduced loneliness. Access to collective efficacy significantly predicted better mental health; the predictive validity of the subscales improved when combined with self-efficacy.

CONCLUSION

The CENS is an acceptable and psychometrically robust measure of collective efficacy in personal social networks.

PRACTICE IMPLICATIONS

Measuring collective efficacy with self-efficacy will provide useful information for researchers and policymakers interested in capacity for self-management and social determinants of behaviour change.

Sputum proteomic signature of gastro-oesophageal reflux in patients with severe asthma

Gastro-oesophageal reflux disease (GORD) has long been associated with poor asthma control without an established cause-effect relationship. 610 asthmatics (421 severe/88 mild-moderate) and 101 healthy controls were assessed clinically and a subset of 154 severe asthmatics underwent proteomic analysis of induced sputum using untargeted mass spectrometry, LC-IMS-MS^E. Univariate and multiple logistic regression analyses (MLR) were conducted to identify proteins associated with GORD in this cohort. When compared to mild/moderate asthmatics and healthy individuals, respectively, GORD was three- and ten-fold more prevalent in severe asthmatics and was associated with increased asthma symptoms and oral corticosteroid use, poorer quality of life, depression/anxiety, obesity and symptoms of sino-nasal disease. Comparison of sputum proteomes in severe asthmatics with and without active GORD showed five differentially abundant proteins with described roles in anti-microbial defences, systemic inflammation and epithelial integrity. Three of these were associated with active GORD by multiple linear regression analysis: Ig lambda variable 1-47 (p = 0·017) and plasma protease C1 inhibitor (p = 0·043), both in lower concentrations, and lipocalin-1 (p = 0·034) in higher concentrations in active GORD. This study provides evidence which suggests that reflux can cause subtle perturbation of proteins detectable in the airways lining fluid and that severe asthmatics with GORD may represent a distinct phenotype of asthma.

"Velcro-type" crackles predict specific radiologic features of fibrotic interstitial lung disease

BACKGROUND

"Velcro-type" crackles on chest auscultation are considered a typical acoustic finding of Fibrotic Interstitial Lung Disease (FILD), however whether they may have a role in the early detection of these disorders has been unknown. This study investigated how "Velcro-type" crackles correlate with the presence of distinct patterns of FILD and individual radiologic features of pulmonary fibrosis on High Resolution Computed Tomography (HRCT).

METHODS

Lung sounds were digitally recorded from subjects immediately prior to undergoing clinically indicated chest HRCT. Audio files were independently assessed by two chest physicians and both full volume and single HRCT sections corresponding to the recording sites were extracted. The relationships between audible "Velcro-type" crackles and radiologic HRCT patterns and individual features of pulmonary fibrosis were investigated using multivariate regression models.

RESULTS

148 subjects were enrolled: bilateral "Velcro-type" crackles predicted the presence of FILD at HRCT (OR 13.46, 95% CI 5.85-30.96, p < 0.001) and most strongly the Usual Interstitial Pneumonia (UIP) pattern (OR 19.8, 95% CI 5.28-74.25, p < 0.001). Extent of isolated reticulation (OR 2.04, 95% CI 1.62-2.57, p < 0.001), honeycombing (OR 1.88, 95% CI 1.24-2.83, < 0.01), ground glass opacities (OR 1.74, 95% CI 1.29-2.32, p < 0.001) and traction bronchiectasis (OR 1.55, 95% CI 1.03-2.32, p < 0.05) were all independently associated with the presence of "Velcro-type" crackles.

CONCLUSIONS

"Velcro-type" crackles predict the presence of FILD and directly correlate with the extent of distinct radiologic features of pulmonary fibrosis. Such evidence provides grounds for further investigation of lung sounds as an early identification tool in FILD.

Validation of the CHADS2 clinical prediction rule to predict ischaemic stroke

The CHADS2 predicts annual risk of ischaemic stroke in non-valvular atrial fibrillation. This systematic review and meta-analysis aims to determine the predictive value of CHADS2. The literature was systematically searched from 2001 to October 2010. Data was pooled and analysed using discrimination and calibration statistical measures, using a random effects model. Eight data sets (n=2815) were included. The diagnostic accuracy suggested a cut-point of ≥1 has higher sensitivity (92%) than specificity (12%) and a cut-point of ≥4 has higher specificity (96%) than sensitivity (33%). Lower summary estimates were observed for cut-points ≥2 (sensitivity 79%, specificity 42%) and ≥3 (specificity 77%, sensitivity 50%). There was insufficient data to analyse cut-points ≥5 or ≥6. Moderate pooled c statistic values were identified for the classic (0.63, 95% CI 0.52–0.75) and revised (0.60, 95% CI 0.43–0.72) view of stratification of the CHADS2 . Calibration analysis in-dicated no significant difference between the predicted and observed strokes across the three risk strata for the classic or revised view. All results were associated with high heterogeneity, and conclusions should be made cautiously. In conclusion, the pooled c statistic and calibration analysis suggests minimal clinical utility of both the classic and revised view of the CHADS2 in predicting ischaemic stroke across all risk strata. Due to high heterogeneity across studies and low event rates across all risk strata, the results should be interpreted cautiously. Further validation of CHADS2 should perhaps be undertaken, given the methodological differences between many of the available validation studies and the original CHADS2 derivation study.

On distributions having the almost-lack-of-memory property

It is shown that random variables X exist, not exponentially or geometrically distributed, such that

P{X – b ≧ x | X ≧ b} = P{X ≧ x}

for all x > 0 and infinitely many different values of b. A class of distributions having the given property is exhibited. We call them ALM distributions, since they almost have the lack-of-memory property. For a given subclass of these distributions some phenomena relating to service by an unreliable server are discussed.

On a new characterization of the exponential distribution related to a queueing system with an unreliable server

In this paper we derive a new property of the exponential distribution, closely related to a single-server queueing system with unreliable server. We show that this new property is another characterization of the exponential law.

The Service Time Properties of an Unreliable Server Characterize the Exponential Distribution

Consider the total service time of a job on an unreliable server under preemptive-repeat-different and preemptive-resume service disciplines. With identical initial conditions, for both cases, we notice that the distributions of the total service time under these two disciplines coincide, when the original service time (without interruptions due to server failures) is exponential and independent of the server reliability. We show that this fact under varying server reliability is a characterization of the exponential distribution. Further we show, under the same initial conditions, that the coincidence of the mean values also leads to the same characterization.

Multidimensional endotypes of asthma: topological data analysis of cross-sectional clinical, pathological, and immunological data

BACKGROUND

Incomplete understanding of mechanisms and clinicopathobiological heterogeneity in asthma hinders research progress. Pathogenic roles for T-helper-type 17 (Th17) cells and invariant T cells implied by murine data have yet to be assessed in man. We aimed to investigate the role of Th17 and mucosal associated invariant T (MAIT) cells in airway inflammation; to characterise associations between diverse clinical and immunological features of asthma; and to identify novel multidimensional asthma endotypes.

METHODS

In this single-centre, cross-sectional observational study in the UK, we assessed volunteers with mild-to-severe asthma and healthy non-atopic controls using clinical and physiological assessment and immunological sampling of blood, induced sputum, endobronchial biopsy, and bronchoalveolar lavage for flow cytometry and multiplex-electrochemiluminescence assays. Primary outcomes were changes in frequencies of Th17 and MAIT cells between health and asthma using Mann-Whitney U tests and the Jonckheere-Terpstra test (linear trend across ranked groups). The study had 80% power to detect 60% differences in T-cell frequencies at p<0·05. Bayesian Network Analysis (BNA) was used to explore associations between parameters. Topological Data Analysis (TDA) was used to identify multidimensional endotypes. The study had local research ethics approval. All participants provided informed consent.

FINDINGS

Participants were 84 male and female volunteers (60 with mild-to-severe asthma and 24 healthy, non-atopic controls) aged 18-70 years recruited from clinics and research cohorts. Th17 cells and γδ17 cells were not associated with asthma, even in severe neutrophilic forms. MAIT-cell frequencies were strikingly reduced in asthma compared with health (median frequency in blood 0·9% of CD3+ cells [IQR 0·3-1·8] in asthma vs 1·6 [1·2-2·6] in health, p=0·005; in sputum 1·1 [0·7-2·0] vs 1·8 [1·6-2·3], p=0·002; and in biopsy samples 1·3 [0·7-2·3] vs 3·9% [1·3-5·3%], p=0·02), especially in severe asthma where BAL regulatory T cells were also reduced compared with those in health (4·4, 3·1-6·1, vs 8·1, 5·6-10; p=0·02). BNA and TDA identified six novel clinicopathobiological clusters of underlying disease mechanisms, with elevated mast cell mediators tryptase (p<0·0001), chymase (p=0·02), and carboxypeptidase A3 (p=0·02) in severe asthma.

INTERPRETATION

This study suggests that Th17 cells do not have a major pathogenic role in human asthma. We describe a novel deficiency of MAIT cells in severe asthma. We also provide proof of concept for application of TDA to identification of multidimensional clinicopathobiological endotypes. Endotypes will require validation in further cohorts.

FUNDING

Wellcome Trust.

Fluorescent imaging for assessment of the effect of combined application of electroporation and rifampicin on HaCaT cells as a new therapeutic approach for psoriasis

The study aimed to clarify the role of electric pulses in combination with chemotherapy on the viability of keratinocyte cell line HaCaT, in the context of its application as a new therapeutic approach for psoriasis. The data show that electroporation of HaCaT cells in combination with rifampicin induces cytoskeleton disruption and increases permeability of cell monolayer due to cell-cell junctions' interruption, visualized by fluorescent imaging of E-cadherin and actin integrity. This was accompanied with synergistic reduction of cell viability. The study proposes a new opportunity for more effective skin treatment than chemotherapy. The future application of this electrochemotherapeutic approach for combined local treatment of psoriasis may have serous benefits because of a high possibility to avoid side-effects of conventional chemotherapy.

A targeted e-learning program for surgical trainees to enhance patient safety in preventing surgical infection

INTRODUCTION

Surgical site infection accounts for 20% of all health care-associated infections (HCAIs); however, a program incorporating the education of surgeons has yet to be established across the specialty.

METHODS

An audit of surgical practice in infection prevention was carried out in Beaumont Hospital from July to November 2009. An educational Web site was developed targeting deficiencies highlighted in the audit. Interactive clinical cases were constructed using PHP coding, an HTML-embedded language, and then linked to a MySQL relational database. PowerPoint tutorials were produced as online Flash audiovisual movies. An online repository of streaming videos demonstrating best practice was made available, and weekly podcasts were made available on the iTunes© store for free download. Usage of the e-learning program was assessed quantitatively over 6 weeks in May and June 2010 using the commercial company Hitslink.

RESULTS

During the 5-month audit, deficiencies in practice were highlighted, including the timing of surgical prophylaxis (33% noncompliance) and intravascular catheter care in surgical patients (38% noncompliance regarding necessity). Over the 6-week assessment of the educational material, the SurgInfection.com Web pages were accessed more than 8000 times; 77.9% of the visitors were from Ireland. The most commonly accessed modality was the repository with interactive clinical cases, accounting for 3463 (43%) of the Web site visits. The average user spent 57 minutes per visit, with 30% of them visiting the Web site multiple times.

DISCUSSION

Interactive virtual cases mirroring real-life clinical scenarios are likely to be successful as an e-learning modality. User-friendly interfaces and 24-hour accessibility will increases uptake by surgical trainees.

Prevention of HIV and sexually transmitted diseases in high risk social networks of young Roma (Gypsy) men in Bulgaria: randomised controlled trial

OBJECTIVE

To determine the effects of a behavioural intervention for prevention of HIV and sexually transmitted diseases that identified, trained, and engaged leaders of Roma (Gypsy) men's social networks to counsel their own network members.

DESIGN

A two arm randomised controlled trial.

SETTING

A disadvantaged, impoverished Roma settlement in Bulgaria.

PARTICIPANTS

286 Roma men from 52 social networks recruited in the community.

INTERVENTION

At baseline all participants were assessed for HIV risk behaviour, tested and treated for sexually transmitted diseases, counselled in risk reduction, and randomised to intervention or control groups. Network leaders learnt how to counsel their social network members on risk prevention. Networks were followed up three and 12 months after the intervention to determine evidence of risk reduction.

MAIN OUTCOME MEASURE

Occurrence of unprotected intercourse during the three months before each assessment.

RESULTS

Reported prevalence of unprotected intercourse in the intervention group fell more than in control group (from 81% and 80%, respectively, at baseline to 65% and 75% at three months and 71% and 86% at 12 months). Changes were more pronounced among men with casual partners. Effects remained strong at long term follow-up, consistent with changes in risk reduction norms in the social network. Other measures of risk reduction corroborated the intervention's effects.

CONCLUSIONS

Endorsement and advice on HIV prevention from the leader of a social network produces well maintained change in the reported sexual practices in members of that network. This model has particular relevance for health interventions in populations such as Roma who may be distrustful of outsiders.

TRIAL REGISTRATION

Clinical Trials NCT00310973.

Mesomelic form of chondrodysplasia and congenital glaucoma associated with de novo translocation (13;18)(q14;q23)

Mesomelic form of chondrodysplasia and congenital glaucoma associated with de novo translocation (13;18)(q14:q23): Mesomelic dysplasias are characterized by limb shortening most prominent of the middle segment of the extremities (forearm and lower leg). In addition to several syndromic forms a few patients with sporadic or familial forms and without precise nosological classification have been reported so far. In this report we present a young female with disproportionate mesomelic dwarfism, dysmorphic facial features, bilateral glaucoma, patent ductus arteriosus, low and hoarse voice, and generalized muscular hypotonia. At the age of 2.5 years mental development is normal. High resolution G-banded chromosome studies revealed a de novo reciprocal translocation with karyotype 46,XX t (13;18)(q14;q23). The concurrence of this de novo autosomal translocation with this distinct phenotype supports the hypothesis that disruption of (a) gene(s) at the translocation breakpoints causes this unusual, apparently new form of skeletal chondrodysplasia.

[Endorectal echography--diagnostic relevance in pararectal and perivesical region diseases]

The diagnostic relevance of endorectal ultrasonography is assessed in a series of 56 patients presenting surgical, urological and obstetric-gynecological conditions, distributed as follows: carcinoma of the rectum (30 cases), prostate gland pathology (12 men) and uterine neck carcinoma (14 women). Endorectal echography contributes greatly to preoperative staging of the patients with rectal carcinoma. In prostate gland diseases it proves helpful in making the diagnosis before and after the treatment. In conclusion it is underscored that endorectal echography is a noninvasive procedure highly effective economically.

Malignant melanoma of the skin and non-Hodgkin's lymphoma in USA: a comparative epidemiological study

Possible associations of incidence of non-Hodgkin's lymphoma (NHL) with solar UVR have been suggested (Cartwright e.a. 1994, etc.). Also, incidence for both malignant melanoma of the skin (SMM) and NHL has shown a rapid increase over the last 10-15 years worldwide. On the other hand, cyclicity in variations of incidence rates for SMM was reported (Houghton e.a. 1981, Dimitrov 1998, etc.). The present study analysed trends and variations in incidence of SMM and NHL for the USA. Annual age-standardized incidence rates for SMM and NHL (SEER database, 1973-1989) were compared. Linear and non-linear regression modeling, periodogram regression analysis and parametric tests were applied (Dimitrov e.a. 1995). The analysis denoted non-linear trends of increasing incidence for both SMM and NHL. Cyclic variations in incidence rates for SMM in US females were reported previously (Dimitrov 1993) and now were confirmed also for other strata of the population (mainly, cycles with a period T = 8 divided by 9 years, p < 0.05) as well as revealed for NHL (mainly, cycles with a period T = 8 divided by 9 years). This cyclicity was significant at 95% only for black US males (Table 1). After decycling for hypercyclicity of 20-35 years (long-term cyclic trends), however, significant high-frequency infrannual variations of 3 divided by 5 years appeared in NHL (latter cyclic variations, for instance, were observed in the sunspots index, solar UVR and stratospheric ozone). Also, significant cycles of 11-13 years appeared for white US males. Similar cyclicity of 9 divided by 11 years was observed in sunspots number over the same interval. Trends of NHL were very similar to that of SMM, as were the variations. This study might be considered a contribution to the hypothesis on possible associations of incidence for NHL with heliogeophysical phenomena.

Karyotype study of Rana camerani and comparisons with the other 26-chromosome European brown frog species (Amphibia, Anura)

The results of a detailed morphological and morphometrical chromosome analysis of Rana camerani (2n = 26) are described. It was established that the karyotype of this species consisted of three homologous pairs of large metacentrics, two homologous pairs of large submetacentrics, three homologous pairs of small metacentrics, two homologous pairs of small submetacentrics, and three homologous pairs of small subtelocentrics. Morphologically discernible sex chromosomes were not found. The similarity and peculiarities in the R. camerani karyotype and those of R. temporaria, R. dalmatina and R. graeca are discussed. This comparative karyotype analysis has suggested the possibility for developing a general chromosomal formula, by means of which these 26-chromosome species could be characterized.

Mechanically evoked cerebral potentials to sudden ankle dorsiflexion in human subjects during standing

Mechanically evoked cerebral potentials (MECP) were studied in humans standing on a movable platform with three different stance widths. A sudden platform tilt of 4 degrees produced ankle dorsiflexion and resulted in scalp potentials of five distinct components, the earliest being a positive deflection at 35/60 ms. Their latencies have shown fairly consistent values among the three stance widths, while the amplitudes underwent some significant changes under the wide stance condition as compared with tightly close feet. These findings were interpreted as purporting evidence of altered somaesthetic afferent input from lower limbs during standing with widely apart support surface.

Brain macropotentials associated with distinct phases of voluntary sustained isometric contraction in man

Brain potentials recorded from the scalp during voluntary sustained isometric contraction have been consistently found to accompany both the beginning and the termination of the contraction. This study attempts to evaluate the dependence of the potentials related to the voluntary termination of a sustained effort on the physical parameters of the motor task and also to further investigate the relationship between potentials related to the initiation and to the termination of action. Brain potentials from healthy male volunteers performing hand-grip squeeze were time-locked to (1) beginning of contraction; (2) execution of an additional effort; and (3) the moment of voluntary relaxation, and then averaged. The waveshape and amplitude of the entire potential curve preceding and following the decision to act were evaluated with best-fit mathematical approximation procedures. Few correlations between the various descriptive parameters of the three types of potentials were found. The brain potentials accompanying beginning of the contraction from state of rest differed significantly from those accompanying execution of an additional effort and both potentials preceding initiation of voluntary effort differed from potentials preceding decision to terminate the action. It is hypothesised that brain macropotentials are linked to separate underlying commands for initiation and termination of voluntary action.

Modulation of somatosensory evoked potentials during coordination between posture and movement

Somatosensory evoked potentials (SEPs) elicited during execution of voluntary movements undergo modification in their amplitude ('gating'). We have studies SEP changes during a motor task that includes anticipatory postural adjustment and focal movement. Upright standing subjects were performing fast forward elevation of one arm. The electrical stimulus was presented over the ipsilateral posterior tibial nerve within two different time frames: (1) preceding the EMG activity of femoral biceps muscle, known to be first in occurrence in such task; (2) during this EMG activity, yet before the EMG occurrence in anterior deltoid muscle-prime mover for the forward arm elevation. The following significant changes in SEPs preceding focal movements as compared with control SEPs during quiet stance were found: The early component P42-N50 showed a marked decrease, regardless of its time relation to the anticipatory activity in the leg. Component N50-P60 increased in amplitude, more so when elicited within an earlier time frame. Thus, diminution of amplitude as an expression of gating, was found to exist already before the occurrence of anticipatory postural adjustment activity and to persist during the ensuing focal movement.

Induced androgenesis in alfalfa (Medicago sativa L.)

Anthers of 10 alfalfa (Medicago sativa L.) lines were used as initial material for the production of androgenic haploids. More than 30 variants of nutrient media were tested. Twenty five different treatments with low temperatures and gamma rays were tried in order to find optimal conditions for callus induction and organogenesis.The genotype, stage of microspore development, phytohormonal composition of the nutrient media and pretreatment with physical agents, alone or in combination, affected the efficiency of organogenesis and regeneration in anther cultures of alfalfa.Plants exhibited a high degree of variability in their chromosome number. Haploids, dihaploids and mixoploids were obtained.Cytological studies of in vitro pollen development revealed the origin of the regenerants from microspores.

Comparative analysis of sister-chromatid exchanges in plant and human chromosomes

Species specificity concerning the two main SCE characteristics, namely frequency and localization, of "spontaneous" SCEs in plant cells (root tips of Crepis capillaris) and in human lymphocytes was investigated under comparable conditions. The FPG technique was used for detection of SCEs after bifilar incorporation of BrdU into DNA (TB-BB). Data of parallel experiments showed that the frequency of SCEs in plant cells was considerably higher than that observed in human lymphocytes--13.2 and 7.3 SCEs per cell respectively. The difference was even more pronounced when the SCE frequency was estimated on the basis of DNA content/cell (pg). Analysis of SCE distribution was limited to SCEs localized in the centromere, since contradictory results most frequently concerned this chromosome region. The data of the present experiments showed that the frequency of SCEs localized in the centromere regions of plant chromosomes was considerably lower than that observed in human chromosomes. Compared with the relative sizes of the centromere regions in the two genomes, however, these frequencies proved to be quite similar. In both systems the centromeres were involved in SCE, as could be expected for random distribution, along the length of the chromosomes.

Somatosensory evoked potentials during compound thumb movement

The aim of the study was to assess the influence of a biphasic flexion-extension movement upon somatosensory evoked potentials (SEPs). Voluntary thumb flexion initiated a sequence of either single or single PLUS sustained electrical stimulation upon the median nerve. In cases of sustained stimulation the subjects had to overcome the induced tetanic thumb flexion. During movements the latencies of early components were longer compared to rest; during simple movements the amplitudes of most components were diminished compared to rest; the amplitudes of early components were further diminished in movements against tetanic contraction compared to simple ones; the suppression of SEP amplitudes was similar regardless of possibility to overcome the opposing tetanic contraction; the changes in SEP amplitudes were not dependent on training.

Movement related brain potentials accompanying a non-productive voluntary action in humans

This study assessed the effects of training and ability to execute a voluntary movement upon movement-related brain potentials (MRBPs). A self-paced thumb flexion initiated a sequence of autotriggered electrical stimuli over the median nerve that caused a twitch opposing the intended thumb extension. The MRBPs had earlier onsets during the first runs of skill acquisition than during later training sessions; they occurred earlier when they preceded a stimulus train than when they preceded a single stimulus; the onset was earlier over the vertex than over the premotor area. MRBP duration was longer during train stimulation when a voluntary effort had to be maintained against tetanic contraction. MRBP amplitude did not reflect task requirements under these experimental conditions.

[Treatment of peptic ulcer with sucralfate]

Sucralfate made in Bulgaria (Farmaphim) and its Yugoslavian analogue venter have been tried in gastroduodenal ulcer. The drugs were given per os (1 g, 1 tablet) 4 times a day before meals for 20 days. Sucralfate treatment was assigned to 26 patients with gastric and 26 with duodenal ulcer. The other 20 gastric ulcer patients received venter. 10 patients with gastric and 20 with duodenal ulcer entered the control group receiving placebo. Attenuation of the symptoms was reported as early as on day 4 of the treatment in 85-100% of the patients both with gastric and duodenal ulcer. The 20-day course of sucralfate treatment brought about a complete epithelization on gastric ulcer in 54% while in venter treatment in 55% of those treated versus placebo group 10%. Duodenal ulcer epithelization occurred in sucralfate-treated group in 58% against placebo group 17%. The differences in treatment results between sucralfate and venter are immaterial, whereas against placebo they are significant (p less than 0.05). Side effects were not serious.

Cisapride and cimetidine in the treatment of erosive esophagitis

The efficacy of cisapride, as compared with cimetidine, in the treatment of erosive esophagitis was studied in a double-blind trial. One hundred and twenty-nine patients were assigned to one of four dosage schedules: cisapride 10 mg b.i.d. (20 mg group) or q.i.d. (40 mg group), or cimetidine 400 mg b.i.d. (800 mg group) or q.i.d. (1600 mg group). Treatment lasted 8 to 12 weeks. The degree of esophagitis and the severity of diurnal and nocturnal heartburn and regurgitation were significantly (p less than 0.01) reduced in the four treatment groups. Endoscopy did not show any significant differences among the four groups, although cisapride tended to be more effective in moderate to severe esophagitis, in which cases mucosal healing (i.e. absence of erosions and ulcers) was observed in 69%, 64%, 55% and 55% of the patients treated with cisapride 40 mg, cisapride 20 mg, cimetidine 1600 mg and cimetidine 800 mg. Improvement in reflux symptoms in the two cisapride groups was not significantly different from that in the cimetidine 1600 mg group, but was better (p less than 0.05) than that in the cimetidine 800 mg patients. The severity score for all reflux symptoms had decreased by 79%, 74% (cisapride 40 mg and 20 mg), 69% and 57% (cimetidine 1600 mg and 800 mg) by the end of treatment. These results show that cisapride is at least as effective as acid-suppressing therapy in patients with reflux esophagitis, and is therefore a valuable alternative to it.

Motor learning in patients with cerebellar dysfunction

This study examined whether cerebellar dysfunction resulted in deficiencies of motor learning. Patients with cerebellar atrophy only or cerebellar atrophy combined with atrophy of the brainstem and age-matched normal subjects performed two tasks to assess improvements in skilled performance. The first task was repetitive tracing with the hand of an irregular geometric pattern with normal visual guidance, and the second task was repetitive tracing of a different geometric pattern with mirror-reversed vision. Patients with pathology limited to the cerebellum showed impairments in the skilled performance of the movement performed with normal vision that may have been related to a failure to alter movement strategy. Patients with added pathology in the brainstem exhibited impairments in adapting to mirror-reversed vision. Subsidiary experiments indicated that improvements of movements guided by mirror-reversed vision were mediated by vision. These results indicate that the cerebellum and its associated input pathways are involved in motor skill learning.

Differential influence of posture and intentional movement on human somatosensory evoked potentials evoked by different stimuli

Somatosensory evoked potentials (SEP) recorded from humans were elicited by a cutaneous shock to the index finger or with a ramp displacement of the finger that stretched the first dorsal interosseous muscle. A somatosensory stimulus was presented while a subject maintained a steady posture of the metacarpophalangeal joint or during a rapid voluntary abduction of the index finger. Both activities were performed against a constant opposing load of 0.15 Nm or without a load. SEPs were recorded over the postcentral arm area, together with the electromyogram of the first dorsal interosseous muscle. The major components of the SEPs were P56, N130, P174, N232 and P294. The amplitudes of all components were diminished substantially during active movement. A constant load opposing postural fixation or active movement did not influence the SEP amplitude. The amplitude of the P56 component was differentially affected by the shock or ramp stimuli. The findings demonstrate that active movement gates sensory input, while sustained tonic muscular activity with an opposing constant load does not, and that different somesthetic inputs may be processed differently during movement.