François Tremblay

Role of Primary Somatosensory Cortex in Active and Passive Touch

Publisher Summary The sensory and motor capabilities of the hand in humans and other nonhuman primates are highly developed and together confer a special evolutionary advantage to primates. When the hand is used as a sensory organ, specifically for discriminative touch and stereognosis, then the movements become subsidiary to the goal of obtaining somesthetic feedback. It is argued that the functional role of primary somatosensory (S1) cortex can be fully appreciated only when studied in relation to the various behavioral factors that modify the access of sensory information to the central processing centers, including movement, attention, motivation, motor set, and arousal. Movement is used as an example of one such behavioral factor. The importance of movement to touch is underlined by the observation that tactile perception is better when there is movement between the stimulus and the skin, as compared to when the same stimulus is applied statically. The existence of movement-related gating controls over behaviorally relevant cutaneous inputs to S1 cortex may appear to be paradoxical and difficult to reconcile with the highly refined tactile abilities associated with active touch.

Visual cortex controls retinal output in the rat

The first objective of the present investigation was to shed more light on corticofugal influences on the retina by providing an analysis of the type and proportion of retinal ganglion cells that are affected by cooling the visual cortex in rats. The second question was to determine if the pretectum participates in functional cortico-retinal relationships. In urethane-anesthetized and paralyzed hooded rats, axonal activity of retinal ganglion cells was recorded with glass micropipettes at optic chiasm level. Units were classified as ON, OFF, suppressed-by-light and concentric. The visual cortex was inactivated by cooling its surface with a 4 mm2 steel probe using the Peltier effect. The pretectum was blocked with microinjections of 50 to 100 nanoliters of cobalt ions, lidocaine hydrochloride or KCl. The inactivations and recoveries at both sites were monitored by simultaneously recording evoked field potentials. Interrupting corticofugal impulses caused modifications of the evoked discharge pattern in all types of cells. The concentric type was the group least affected by cortical cooling. A common trend emerged suggesting that cooling of the visual cortex led to an enhancement of the initial evoked excitation. This was often followed by an enhanced post-excitatory inhibition. The Pearson coefficient allowed us to measure the degree of similarity between two histograms. When all data were pooled, a weak correlation between control and test histograms (r = 0.29, N = 56) was found, while the control and recovery patterns averaged a correlation of more than twice that size (r = 0.68). In a second series of experiments, the pretectum and visual cortex (VC) were simultaneously inactivated. It is shown that both sites summed their influence and acted synergistically upon the pattern of ganglion cell responses. The results strongly suggest that the visual cortex exerts a major control over the response pattern of thirty percent of retinal ganglion cells, and that the pretectum participates in the functional relationships between visual cortex and retina in rats.

Association between glucose intolerance and bacterial colonisation in an adult population with cystic fibrosis, emergence of Stenotrophomonas maltophilia

BACKGROUND Diabetes is common in cystic fibrosis (CF). Glucose can be detected in the airway when the blood glucose is elevated, which favours bacterial growth. We investigated the relationship between dysglycemia and lung pathogens in CF. METHODS Cross-sectional and prospective analysis of CF patients (N=260) who underwent a 2h-oral glucose tolerance test. Clinical data was collected. RESULTS Stenotrophomonas maltophilia (S. maltophilia) was the sole bacteria increased in dysglycemic (AGT: 20.2%, CFRD: 21.6%) patients compared to normotolerants (NGT: 8.7%). S. maltophilia positive patients with dysglycemia had more pulmonary exacerbation events compared to NGTs (1.22 vs 0.63, P=0.003). The interaction between S. maltophilia colonisation and glucose tolerance status significantly increases the risk of lower lung function (P=0.003). Its growth was not affected by the evolution of the glucose tolerance after three years follow-up. CONCLUSION Prevalence of S. maltophilia was higher in dysglycemic patients, supporting the idea that S. maltophilia is a marker of disease severity in CF.

Arthritis, progressive maculopapular rash and severe peripheral neuropathy in a 60-year-old man

See also the practice article by Vazquez-Lopez and Gonzalez-Lara on page [211][1] and at [www.cmaj.ca/lookup/doi/10.1503/cmaj.130221][2] A 60-year-old man born in Canada was referred to our clinic because of arthritis, a progressive maculopapular rash and severe peripheral neuropathy. He had a

Adrenal Insufficiency in Cystic Fibrosis: A Rare Phenomenon?

Background The prevalence of adrenal insufficiency (AI) in cystic fibrosis (CF) is unknown. The frequent use of glucocorticoids (inhaled or systemic) may induce the long-term suppression of the hypothalamic-pituitary-adrenal axis. Methods We reviewed the results of adrenocorticotropic hormone (ACTH) stimulation tests done over a 10-year period to evaluate adrenal function in 69 CF patients of the CHUM CF clinic. Clinical characteristics of AI patients were compared to adrenal-sufficient (AS) patients. Results AI was confirmed in 33 of the 69 CF patients. A higher rate of dysglycemia (P=0.022) and of Aspergillus positive culture (P=0.006) was observed in AI patients compared to AS patients. Weight, CFTR genotype, and pulmonary function were comparable between AI and AS patients. The use of systemic corticosteroids (SC) prior to the diagnosis of AI was observed in 42.4% of patients. Compared to AI patients without SC, SC-treated AI patients were older and had a higher rate of allergic bronchopulmonary aspergillosis. Conclusion This study is the first to systematically examine the presence of AI in the largest cohort of CF patients studied to date with a prevalence of 8%. Patients treated with corticosteroids and those colonized with Aspergillus have a greater risk of AI.

208 Long-term and seasonal impact of a vitamin D3 (cholecalciferol) supplementation protocol on vitamin D [25(OH)D] serum levels among cystic fibrosis adults in a Montreal clinic

Vitamin D deficiency is a widely reported problem in patients with Cystic Fibrosis (CF). Objectives To analyse the long term and seasonal impact on vitamin D [25(OH)D] serum levels of our vitamin D3 protocol. Methods A retrospective study was performed in our CF adult clinic. Data for 200 patients were obtained from their medical files for 2009, and compared to their own latest data available (2013–2014). Protocol Total starting D3 prescribed dose was 2800 IU/day during the summer months (May to October), 4400 IU/day during the winter months (November to April) or the weekly dose equivalent. Results Population studied: 55% male/45% female, age 34.4±8.3 years, FEV1% 65.1±21.4, BMI 23.2±3.5 kg/m 2 , 85.5% with pancreatic insufficiency. Mean 25(OH)D serum levels were significantly superior after the protocol (64.7±25.6 nmol/L vs 92.3±28.4 nmol/L, p TableLong-term impact of D3 Protocol25(OH)D serum level adequacyProportion of patientsBefore D3 ProtocolAfter D3 ProtocolDeficient, 150 nmo1/L0.5%3% Before the protocol, patients showed significant seasonal variation in 25(OH)D serum levels with lower levels in winter months compared to summer months (58.6±28.6 nmol/L vs 69.6±21.7 nmol/L, p Conclusion This study suggests that a vitamin D3 supplementation protocol with higher doses during winter months was efficient for the long term and seasonal management of vitamin D deficiency in our Montreal adult CF clinic.