Statistical inference in brain graphs using threshold-free network-based statistics.

The description of brain networks as graphs where nodes represent different brain regions and edges represent a measure of connectivity between a pair of nodes is an increasingly used approach in neuroimaging research. The development of powerful methods for edge-wise group-level statistical inference in brain graphs while controlling for multiple-testing associated false-positive rates, however, remains a difficult task. In this study, we use simulated data to assess the properties of threshold-free network-based statistics (TFNBS). The TFNBS combines threshold-free cluster enhancement, a method commonly used in voxel-wise statistical inference, and network-based statistic (NBS), which is frequently used for statistical analysis of brain graphs. Unlike the NBS, TFNBS generates edge-wise significance values and does not require the a priori definition of a hard cluster-defining threshold. Other test parameters, nonetheless, need to be set. We show that it is possible to find parameters that make TFNBS sensitive to strong and topologically clustered effects, while appropriately controlling false-positive rates. Our results show that the TFNBS is an adequate technique for the statistical assessment of brain graphs.

Structural Brain Correlations of Visuospatial and Visuoperceptual Tests in Parkinson's Disease.

BACKGROUND: Diagnosis of mild cognitive impairment in Parkinson's disease (PD) is relevant because it is a marker for evolution to dementia. However, the selection of suitable tests to evaluate separate cognitive domains in mild cognitive impairment related to PD remains an open question. The current work aims to investigate the neuroanatomical correlates of several visuospatial/visuoperceptual tests using the same sample and a multimodal MRI approach. METHODS: The study included 36 PD patients and 20 healthy subjects matched for age, sex, and education. The visuospatial/visuoperceptual tests selected were: Pentagon Copying Test (PCT), Judgment of Line Orientation Test (JLOT), Visual Form Discrimination Test (VFDT), Facial Recognition Test (FRT), Symbol Digit Modalities Test (SMDT), and clock copying task (CLOX2). FreeSurfer was used to assess cortical thickness, and tract-based spatial statistics was used for fractional anisotropy analysis. RESULTS: Lower performance in the PCT, JLOT, and SDMT was associated with extensive cortical thickness reductions in lateral parietal and temporal regions. VFDT and CLOX2 did not show this common pattern and correlated with more limited medial occipito-temporal and occipito-parietal regions. Performance in all visuospatial/visuoperceptual tests correlated with fractional anisotropy in the corpus callosum. CONCLUSIONS: Our findings show that JLOT, SDMT, and PCT, in addition to differentiating patients from controls, are suitable visuospatial/visuoperceptual tests to reflect cortical thinning in lateral temporo-parietal regions in PD patients. We did not observe the dissociation between dorsal and ventral streams that was expected according to the neuropsychological classification of visuospatial and visuoperceptual tests. (JINS, 2018, 24, 33-44).

Effect of extremely low-frequency electromagnetic fields on antioxidant activity in the human keratinocyte cell line NCTC 2544.

Some epidemiological studies have suggested possible associations between exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) and various diseases. Recently, ELF-EMF has been considered as a therapeutic agent. To support ELF-EMF use in regenerative medicine, in particular in the treatment of skin injuries, we investigated whether significant cell damage occurs after ELF-EMF exposure. Reactive oxygen species (ROS) production was evaluated in the human keratinocyte exposed for 1 H to 50 Hz ELF-EMF in a range of field strengths from 0.25 to 2 G. Significant ROS increases resulted at 0.5 and 1 G and under these flux densities ROS production, glutathione content, antioxidant defense activity, and lipid peroxidation markers were assessed for different lengths of time. Analyzed parameters of antioxidant defense and membrane integrity showed a different trend at two selected magnetic fluxes, with a greater sensitivity of the cells exposed to 0.5 G, especially after 1 H. All significant alterations observed in the first 4 H of exposure reverted to controls 24 H after suggesting that under these conditions, ELF-EMF induces a slight oxidative stress that does not overwhelm the metabolic capacity of the cells or have a cytotoxic effect.

New insights into the trophic and cytoprotective effects of creatine in in vitro and in vivo models of cell maturation.

A growing body of scientific reports indicates that the role of creatine (Cr) in cellular biochemistry and physiology goes beyond its contribution to cell energy. Indeed Cr has been shown to exert multiple effects promoting a wide range of physiological responses in vitro as well as in vivo. Included in these, Cr promotes in vitro neuron and muscle cell differentiation, viability and survival under normal or adverse conditions; anabolic, protective and pro-differentiative effects have also been observed in vivo. For example Cr has been shown to accelerate in vitro differentiation of cultured C2C12 myoblasts into myotubes, where it also induces a slight but significant hypertrophic effect as compared to unsupplemented cultures; Cr also prevents the anti-differentiation effects caused by oxidative stress in the same cells. In trained adults, Cr increases the mRNA expression of relevant myogemic factors, protein synthesis, muscle strength and size, in cooperation with physical exercise. As to neurons and central nervous system, Cr favors the electrophysiological maturation of chick neuroblasts in vitro and protects them from oxidative stress-caused killing; similarly, Cr promotes the survival and differentiation of GABA-ergic neurons in fetal spinal cord cultures in vitro; in vivo, maternal Cr supplementation promotes the morpho-functional development of hippocampal neurons in rat offsprings. This article, which presents also some new experimental data, focuses on the trophic, pro-survival and pro-differentiation effects of Cr and examines the ensuing preventive and therapeutic potential in pathological muscle and brain conditions.

Cortical thinning associated with mild cognitive impairment in Parkinson's disease.

The aim of this study was to investigate patterns of cortical atrophy associated with mild cognitive impairment in a large sample of nondemented Parkinson's disease (PD) patients, and its relation with specific neuropsychological deficits. Magnetic resonance imaging (MRI) and neuropsychological assessment were performed in a sample of 90 nondemented PD patients and 32 healthy controls. All underwent a neuropsychological battery including tests that assess different cognitive domains: attention and working memory, executive functions, memory, language, and visuoperceptual-visuospatial functions. Patients were classified according to their cognitive status as PD patients without mild cognitive impairment (MCI; n = 43) and PD patients with MCI (n = 47). Freesurfer software was used to obtain maps of cortical thickness for group comparisons and correlation with neuropsychological performance. Patients with MCI showed regional cortical thinning in parietotemporal regions, increased global atrophy (global cortical thinning, total gray matter volume reduction, and ventricular enlargement), as well as significant cognitive impairment in memory, executive, and visuospatial and visuoperceptual domains. Correlation analyses showed that all neuropsychological tests were associated with cortical thinning in parietotemporal regions and to a lesser extent in frontal regions. These results provide neuroanatomic support to the concept of MCI classified according to Movement Disorders Society criteria. The posterior pattern of atrophy in temporoparietal regions could be a structural neuroimaging marker of cognitive impairment in nondemented PD patients. All of the neuropsychological tests reflected regional brain atrophy, but no specific patterns were seen corresponding to impairment in distinct cognitive domains.

Identification and Treatment of Lung Cancer Oncogenic Drivers in a Diverse Safety Net Setting.

INTRODUCTION: Advances in the testing and treatment of patients with non-small cell lung cancer (NSCLC) harboring oncogenic drivers have improved outcomes. Little is known about testing and treatment patterns in diverse patient populations. METHODS: We conducted a retrospective study in a diverse cohort of patients treated in the John Peter Smith safety net healthcare system. We determined patterns of blood- and tissue-based testing and treatment of patients with EGFR and ALK alterations. Cox proportional-hazards regression models were used to assess the impact of EGFR and ALK testing. RESULTS: A total of 220 patients were included, 97 (44%) were non-Hispanic White, 72 (33%) were Black, 28 (13%) were Hispanic, and 23 (10%) were Asian. EGFR and ALK testing increased over time from 55% and 52%, respectively, in 2017 to 87% and 82%, respectively, in 2021. Frequency of EGFR alterations were highest in Asian patients (45%) and comparable among other groups (6-13%). Frequency of ALK alterations were highest in Hispanic (13%), and Asian (11%) patients, and were 2% for both Black and non-Hispanic White patients. In a multivariate model, lack of testing was associated with worse survival (aHR 1.6; P = .003) and testing positive for EGFR (aHR 0.43; P = .01) or ALK (aHR 0.28; P = .04) was associated with improved survival. Race and ethnicity were not associated with survival differences. CONCLUSION: As molecular testing for oncogenic mutations in NSCLC increases, druggable alterations such as ALK and EGFR can be identified in all race-ethnicity groups and are associated with improved outcomes.

Deep brain stimulation in treatment resistant schizophrenia: A pilot randomized cross-over clinical trial.

BACKGROUND: Up to 30% of patients with schizophrenia are resistant to antipsychotic drug treatment, with 60% of such cases also failing to respond to clozapine. Deep brain stimulation (DBS) has been used in treatment resistant patients with other psychiatric disorders, but there is a lack of trials in schizophrenia, partly due to uncertainties over where to site the electrodes. This trial aimed to examine the effectiveness of nucleus accumbens (NAcc) and subgenual anterior cingulate cortex (subgenual ACC) targeted DBS; the primary outcome measure was PANSS total score, as assessed fortnightly. METHODS: Eight patients with schizophrenia, who met criteria for treatment resistance and were also resistant to/intolerant of clozapine, were randomly assigned using central allocation to receive DBS in the NAcc or subgenual ACC. An open stabilization phase lasting at least six months was followed by a randomized double-blind crossover phase lasting 24 weeks in those who met symptomatic improvement criteria. The primary end-point was a 25% improvement in PANSS total score. (ClinicalTrials.gov Identifier: NCT02377505; trial completed). FINDINGS: One implanted patient did not receive DBS due to complications of surgery. Of the remaining 7 patients, 2/3 with NAcc and 2/4 with subgenual ACC electrode placements met the symptomatic improvement criteria (58% and 86%, and 37% and 68% improvement in PANSS total score, respectively). Three of these patients entered the crossover phase and all showed worsening when the stimulation was discontinued. The fourth patient worsened after the current was switched off accidentally without her or the investigators' knowledge. Physical adverse events were uncommon, but two patients developed persistent psychiatric adverse effects (negative symptoms/apathy and mood instability, respectively). INTERPRETATION: These preliminary findings point to the possibility of DBS having therapeutic effects in patients with schizophrenia who do not respond to any other treatment. Larger trials with careful attention to blinding will be necessary to establish the extent of the benefits and whether these can be achieved without psychiatric side-effects.

Progression of Parkinson's disease patients' subtypes based on cortical thinning: 4-year follow-up.

BACKGROUND: Three cortical atrophy patterns were previously identified in non-demented Parkinson's disease patients using a data-driven approach based on cortical thickness data: i) parieto-temporal pattern of atrophy with worse cognitive performance (pattern 1), ii) occipital and frontal cortical atrophy with younger disease onset (pattern 2), and iii) non-detectable cortical atrophy (pattern 3). We aimed to investigate the evolution of these three patterns over time. METHODS: Magnetic resonance imaging and neuropsychological assessment were obtained at baseline and follow-up (3.8 ±â€¯0.4 year apart) in a group of 45 Parkinson's disease patients and 22 healthy controls. FreeSurfer was used for cortical thickness analysis and global atrophy measures. RESULTS: Temporo-parietal cortical thinning occurred in pattern 2, 3 and controls groups, and patients showed decline in processing speed (as measured by the Stroop Word-Color test, the Symbol Digits Modalities test and the Trail Making Test Part B) and in semantic fluency (animals). Pattern 3 patients showed more progressive cortical thinning in the left prefrontal cortex than controls and more right occipital thinning than pattern 2 patients over time. Pattern 1 patients had greater compromise in activities of the daily living and suffered higher attrition rate. CONCLUSION: The Parkinson's disease phenotypes identified using cluster analysis of cortical thickness data showed different progression over time. The presence of prefrontal thinning and younger disease onset at baseline was associated to less cortical degeneration, while non-atrophic patients progressed showing a temporo-parietal cortical thinning.

Gray/White Matter Contrast in Parkinson's Disease.

Gray/white matter contrast (GWC) decreases with aging and has been found to be a useful MRI biomarker in Alzheimer's disease (AD), but its utility in Parkinson's disease (PD) patients has not been investigated. The aims of the study were to test whether GWC is sensitive to aging changes in PD patients, if PD patients differ from healthy controls (HCs) in GWC, and whether the use of GWC data would improve the sensitivity of cortical thickness analyses to differentiate PD patients from controls. Using T1-weighted structural images, we obtained individual cortical thickness and GWC values from a sample of 90 PD patients and 27 controls. Images were processed with the automated FreeSurfer stream. GWC was computed by dividing the white matter (WM) by the gray matter (GM) values and projecting the ratios onto a common surface. The sample characteristics were: 52 patients and 14 controls were males; mean age of 64.4 ± 10.6 years in PD and 64.7 ± 8.6 years in controls; 8.0 ± 5.6 years of disease evolution; 15.6 ± 9.8 UPDRS; and a range of 1.5-3 in Hoehn and Yahr (H&Y) stage. In both PD and controls we observed significant correlations between GWC and age involving almost the entire cortex. When applying a stringent cluster-forming threshold of p < 0.0001, the correlation between GWC and age also involved the entire cortex in the PD group; in the control group, the correlation was found in the parahippocampal gyrus and widespread frontal and parietal areas. The GWC of PD patients did not differ from controls', whereas cortical thickness analyses showed thinning in temporal and parietal cortices in the PD group. Cortical thinning remained unchanged after adjusting for GWC. GWC is a very sensitive measure for detecting aging effects, but did not provide additional information over other parameters of atrophy in PD.

Cortical atrophy patterns in early Parkinson's disease patients using hierarchical cluster analysis.

INTRODUCTION: Cortical brain atrophy detectable with MRI in non-demented advanced Parkinson's disease (PD) is well characterized, but its presence in early disease stages is still under debate. We aimed to investigate cortical atrophy patterns in a large sample of early untreated PD patients using a hypothesis-free data-driven approach. METHODS: Seventy-seven de novo PD patients and 50 controls from the Parkinson's Progression Marker Initiative database with T1-weighted images in a 3-tesla Siemens scanner were included in this study. Mean cortical thickness was extracted from 360 cortical areas defined by the Human Connectome Project Multi-Modal Parcellation version 1.0, and a hierarchical cluster analysis was performed using Ward's linkage method. A general linear model with cortical thickness data was then used to compare clustering groups using FreeSurfer software. RESULTS: We identified two patterns of cortical atrophy. Compared with controls, patients grouped in pattern 1 (n = 33) were characterized by cortical thinning in bilateral orbitofrontal, anterior cingulate, and lateral and medial anterior temporal gyri. Patients in pattern 2 (n = 44) showed cortical thinning in bilateral occipital gyrus, cuneus, superior parietal gyrus, and left postcentral gyrus, and they showed neuropsychological impairment in memory and other cognitive domains. CONCLUSIONS: Even in the early stages of PD, there is evidence of cortical brain atrophy. Neuroimaging clustering analysis is able to detect two subgroups of cortical thinning, one with mainly anterior atrophy, and the other with posterior predominance and worse cognitive performance.

The Fast-Halo Assay for the Detection of DNA Damage.

The need for express screening of the DNA damaging potential of chemicals has progressively increased over the past 20 years due to the wide number of new synthetic molecules to be evaluated, as well as the adoption of more stringent chemical regulations such as the EU REACH and risk reduction politics. In this regard, DNA diffusion assays such as the microelectrophoretic comet assay paved the way for rapid genotoxicity testing. A more significant simplification and speeding up of the experimental processes was achieved with the fast halo assay (FHA) described in the present chapter. FHA operates at the single cell level and relies on radial dispersion of the fragments of damaged DNA from intact nuclear DNA. The fragmented DNA is separated by diffusion in an alkaline solvent and is stained, visualized, and finally quantified using computer-assisted image analysis programs. This permits the rapid assessment of the extent of DNA breakage caused by different types of DNA lesions. FHA has proven to be sensitive, reliable, and flexible. This is currently one of the simplest, cheapest, and quickest assays for studying DNA damage and repair in living cells. It does not need expensive reagents or electrophoretic equipment and requires only 40 min to prepare samples for computer-based quantification. This technique can be particularly useful in rapid genotoxicity assessments and in high-throughput genotoxicity screenings.

Brain correlates of progressive olfactory loss in Parkinson's disease.

BACKGROUND: Olfactory dysfunction is present in a large proportion of patients with Parkinson's disease (PD) upon diagnosis. However, its progression over time has been poorly investigated. The few available longitudinal studies lack control groups or MRI data. OBJECTIVE: To investigate the olfactory changes and their structural correlates in non-demented PD over a four-year follow-up. METHODS: We assessed olfactory function in a sample of 25 PD patients and 24 normal controls of similar age using the University of Pennsylvania Smell Identification test (UPSIT). Structural magnetic resonance imaging data, obtained with a 3-T Siemens Trio scanner, were analyzed using FreeSurfer software. RESULTS: Analysis of variance showed significant group (F = 53.882; P < 0.001) and time (F = 6.203; P = 0.016) effects, but the group-by-time interaction was not statistically significant. UPSIT performance declined ≥1.5 standard deviations in 5 controls and 7 patients. Change in UPSIT scores of patients correlated positively with volume change in the left putamen, right thalamus, and right caudate nucleus. CONCLUSION: Olfactory loss over time in PD and controls is similar, but we have observed significant correlation between this loss and basal ganglia volumes only in patients.

Discriminating cognitive status in Parkinson's disease through functional connectomics and machine learning.

There is growing interest in the potential of neuroimaging to help develop non-invasive biomarkers in neurodegenerative diseases. In this study, connection-wise patterns of functional connectivity were used to distinguish Parkinson's disease patients according to cognitive status using machine learning. Two independent subject samples were assessed with resting-state fMRI. The first (training) sample comprised 38 healthy controls and 70 Parkinson's disease patients (27 with mild cognitive impairment). The second (validation) sample included 25 patients (8 with mild cognitive impairment). The Brainnetome atlas was used to reconstruct the functional connectomes. Using a support vector machine trained on features selected through randomized logistic regression with leave-one-out cross-validation, a mean accuracy of 82.6% (p < 0.002) was achieved in separating patients with mild cognitive impairment from those without it in the training sample. The model trained on the whole training sample achieved an accuracy of 80.0% when used to classify the validation sample (p = 0.006). Correlation analyses showed that the connectivity level in the edges most consistently selected as features was associated with memory and executive function performance in the patient group. Our results demonstrate that connection-wise patterns of functional connectivity may be useful for discriminating Parkinson's disease patients according to the presence of cognitive deficits.

Ellagitannins in Cancer Chemoprevention and Therapy.

It is universally accepted that diets rich in fruit and vegetables lead to reduction in the risk of common forms of cancer and are useful in cancer prevention. Indeed edible vegetables and fruits contain a wide variety of phytochemicals with proven antioxidant, anti-carcinogenic, and chemopreventive activity; moreover, some of these phytochemicals also display direct antiproliferative activity towards tumor cells, with the additional advantage of high tolerability and low toxicity. The most important dietary phytochemicals are isothiocyanates, ellagitannins (ET), polyphenols, indoles, flavonoids, retinoids, tocopherols. Among this very wide panel of compounds, ET represent an important class of phytochemicals which are being increasingly investigated for their chemopreventive and anticancer activities. This article reviews the chemistry, the dietary sources, the pharmacokinetics, the evidence on chemopreventive efficacy and the anticancer activity of ET with regard to the most sensitive tumors, as well as the mechanisms underlying their clinically-valuable properties.

Creatine Prevents the Structural and Functional Damage to Mitochondria in Myogenic, Oxidatively Stressed C2C12 Cells and Restores Their Differentiation Capacity.

Creatine (Cr) is a nutritional supplement promoting a number of health benefits. Indeed Cr has been shown to be beneficial in disease-induced muscle atrophy, improve rehabilitation, and afford mild antioxidant activity. The beneficial effects are likely to derive from pleiotropic interactions. In accord with this notion, we previously demonstrated that multiple pleiotropic effects, including preservation of mitochondrial damage, account for the capacity of Cr to prevent the differentiation arrest caused by oxidative stress in C2C12 myoblasts. Given the importance of mitochondria in supporting the myogenic process, here we further explored the protective effects of Cr on the structure, function, and networking of these organelles in C2C12 cells differentiating under oxidative stressing conditions; the effects on the energy sensor AMPK, on PGC-1α, which is involved in mitochondrial biogenesis and its downstream effector Tfam were also investigated. Our results indicate that damage to mitochondria is crucial in the differentiation imbalance caused by oxidative stress and that the Cr-prevention of these injuries is invariably associated with the recovery of the normal myogenic capacity. We also found that Cr activates AMPK and induces an upregulation of PGC-1α expression, two events which are likely to contribute to the protection of mitochondrial quality and function.

Withania somnifera Induces Cytotoxic and Cytostatic Effects on Human T Leukemia Cells.

Cancer chemotherapy is characterized by an elevated intrinsic toxicity and the development of drug resistance. Thus, there is a compelling need for new intervention strategies with an improved therapeutic profile. Immunogenic cell death (ICD) represents an innovative anticancer strategy where dying cancer cells release damage-associated molecular patterns promoting tumor-specific immune responses. The roots of Withania somnifera (W. somnifera) are used in the Indian traditional medicine for their anti-inflammatory, immunomodulating, neuroprotective, and anticancer activities. The present study is designed to explore the antileukemic activity of the dimethyl sulfoxide extract obtained from the roots of W. somnifera (WE). We studied its cytostatic and cytotoxic activity, its ability to induce ICD, and its genotoxic potential on a human T-lymphoblastoid cell line by using different flow cytometric assays. Our results show that WE has a significant cytotoxic and cytostatic potential, and induces ICD. Its proapoptotic mechanism involves intracellular Ca(2+) accumulation and the generation of reactive oxygen species. In our experimental conditions, the extract possesses a genotoxic potential. Since the use of Withania is suggested in different contexts including anti-infertility and osteoarthritis care, its genotoxicity should be carefully considered for an accurate assessment of its risk-benefit profile.

Clinical and neurohumoral consequences of diuretic withdrawal in patients with chronic, stabilized heart failure and systolic dysfunction.

BACKGROUND: Loop diuretics are beneficial in heart failure in the short term because they eliminate fluid retention, but in the long-term, they could adversely influence prognosis due to activation of neurohumoral mechanisms. AIMS: To explore the changes induced by diuretic withdrawal in chronic nonadvanced heart failure. METHODS: Diuretics were withdrawn in 26 stabilized heart failure patients with systolic dysfunction (ejection fraction [EF]<45%). Clinical status was evaluated by physical exam, exercise capacity (corridor test) and New York Heart Association (NYHA) class. Biochemical and neurohumoral determinations were performed at baseline and at 3 months. RESULTS: At 3 months, 17 out of 26 patients (65%) were able to tolerate diuretic interruption without a deterioration in exercise capacity or New York Heart Association functional class. Renal function parameters improved (baseline urea 46.2+/-10.8 to 39.2+/-10.1 mg/dl at 3 months, p=0.014; creatinine 1.1+/-0.23 to 0.98+/-0.2 mg/dl, p=0.013). Glucose metabolism also improved (fasting glucose 151+/-91 to 122+/-14 mg/dl, p=0.035). Heart rate and systolic blood pressure did not significantly change, while diastolic blood pressure increased (from 80+/-10 to 87+/-13 mm Hg, p=0.006). Neurohumoral determinations showed a decrease in plasma renin activity (4.19+/-5.96 to 2.88+/-4.98 ng/ml, p=0.026), with no changes in aldosterone, arginine-vasopressin, endothelin-1 and norepinephrine. In contrast, atrial natriuretic peptide significantly increased (115+/-87 to 168+/-155 pg/ml, p=0.004). CONCLUSION: Diuretic withdrawal in stabilized heart failure with systolic dysfunction is associated with an improvement in renal function parameters, glucose metabolism and some neurohumoral parameters, such as plasma renin activity; however, atrial natriuretic peptide levels increased.

Fluoroquinolone therapy in Mycobacterium chelonae keratitis after lamellar keratectomy.

PURPOSE: To characterize a rabbit model of Mycobacterium chelonae keratitis after lamellar keratectomy and assess the effectiveness of fluoroquinolone therapy. SETTING: University Laboratory, University of California, Irvine, California, USA. METHODS: Twenty-eight New Zealand white rabbits had unilateral lamellar keratectomy with placement of 2.5 x 10(5) colony-forming units of log-phase M chelonae under each flap. Eyes (7 per group) were randomized and treated with sterile balanced salt solution, gatifloxacin 0.3%, ciprofloxacin 0.3%, or levofloxacin 0.5% 4 times daily. Two masked observers examined all eyes on days 2, 5, and 7 and weekly for 4 weeks. Severity of disease and bacterial culture results were the main outcomes measured. The means and standard deviations were calculated, and differences between the groups were statistically analyzed. RESULTS: All eyes developed clinical disease. At the time the rabbits were killed, eyes treated with balanced salt solution, ciprofloxacin, levofloxacin, and gatifloxacin were culture positive in 6 (85.7%), 7 (100%), 6 (85.7%), and 3 (42.9%) of 7 eyes per group, respectively. Frequency of positive culture and the severity of clinical disease in gatifloxacin-treated eyes were significantly less (P < .05) than in the other groups combined. CONCLUSIONS: The rabbit model of M chelonae keratitis was successfully developed in our study. A fourth-generation quinolone (gatifloxacin) showed the best performance among the fluoroquinolones tested in our experimental approach. The fourth-generation fluoroquinolone, gatifloxacin, could be effectively used for the treatment of mycobacterial keratitis.

Postulados teóricos sobre la capacitación del profesor guía de la carrera de Medicina / Theoretical postulates about capacity building for the Medicine major guidance professors

La capacitación en la universidad médica es un proceso no excluyente en la formación de los recursos humanos. Es un tema substancial por los cambios que representa en la dirección de nuevos métodos y estilos de preparación y superación del personal docente, en la que se circunscribe el profesor guía, quien juega un rol protagónico dentro del sistema de influencias educativas que actúa sobre el estudiante. El artículo tiene como objetivo de fundamentar los postulados teóricos necesarios que revelan la capacitación del profesor guía de la carrera de Medicina a partir del análisis de algunas de sus conceptualizaciones y de los requisitos que la rigen. Se elaboró la definición de este tipo de capacitación y se contextualizaron algunos de los contenidos tratados. Se concluye que la misma integra en unidad dialéctica las principales funciones, direcciones, cualidades y capacidades del profesor guía; además posee características que la distingue de otros tipos de capacitación.

Capacity building at the medical university is a non-exclusive process in the training of human resources. It is a substantial theme for the changes it represents regarding the direction of new methods and styles of training and improvement of the teaching staff, in which the guidance professor is circumscribed, who also plays a leading role within the system of educational influences that acts on the student. This article was made with the objective of supporting the necessary theoretical postulates that reveal the training of the medical major professors, based on the analysis of some of its conceptualizations and the requirements that govern it. The definition of this type of training was elaborated and some of the contents were contextualized. It was concluded that it is integrates, into a dialectical unit, the main functions, directions, qualities and capacities of the guidance teacher. It also has characteristics that distinguish it from other types of training.

Late benefits of dual-chamber pacing in obstructive hypertrophic cardiomyopathy: a 10-year follow-up study.

OBJECTIVE: To examine the mid-term and long-term outcomes in patients with obstructive hypertrophic cardiomyopathy (HCM) submitted to pacing. DESIGN: Prospective, observational study. SETTING: Single, non-referral centre. PATIENTS AND INTERVENTION: Fifty patients (62 + or - 11 years) with HCM refractory to medical treatment, all in New York Heart Association (NYHA) class III or IV, and with a rest gradient >50 mm Hg underwent a dual-chamber pacemaker implantation. Patients were followed-up for up to 10 years (mean 5.0 + or - 2.9, range 0.6-10.1). RESULTS: During the first year of follow-up, rest gradients decreased (baseline 86 + or - 29 mm Hg; 3 months 55 + or - 37; l year 41 + or - 26; p=0.0001). NYHA class improved, as well as exercise tolerance (baseline 281 + or - 112 m; 3 months 334 + or - 106 m; 1 year 348 + or - 78 m; p<0.0001). The physical and mental components of the quality of life instrument SF-36 also improved. Left ventricular wall thickness remained unchanged, while ejection fraction decreased (baseline 76 + or - 10%; 3 months 74 + or - 8%; 1 year 66 + or - 13%; p=0.002). During the long-term follow-up, an additional reduction in obstruction was found (final rest gradient 28 + or - 24 mm Hg, p<0.02). Those patients who did not improve to NYHA class I or II and continued to have obstruction were given other treatments (six, alcohol ablation; three, surgical myectomy). CONCLUSIONS: Pacing in HCM results in a significant reduction in obstruction, improvement of symptoms and exercise capacity that is progressive and may be achieved after a long period of time. In this series, only 18% of cases needed a more aggressive treatment to relieve residual obstruction and obtain a satisfactory symptomatic status. In conclusion, these results emphasise the need for new controlled studies of pacing with a longer follow-up.