CYSTIC FIBROSIS AND ANTIBIOTIC HYPERSENSITIVITY: PRESENT KNOWLEDGE AND PRACTICAL APPROACH.

Cystic fibrosis is one of the most common fatal genetic diseases (1 in 2500 births). The defect causing the disease is localized on the 7q31 gene, which codifies for the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) transmembrane protein. CFTR is a chloride channel localized on the epithelial cells of the mucosa of the respiratory tract, pancreatic ducts, biliary tree, intestine, vas deferens and sweat glands. More than 2000 different mutations are currently known; some are prominent or relatively frequent, ranging from one population to another. The most frequent complications of cystic fibrosis are those affecting the bronchial tree. Patients suffer from recurrent lung infections, which involve a progressive loss of lung function. The pulmonary infections are frequent or chronic and limit the quality of life of patients. In addition to being enormously exposed to antibiotics, they have many more opportunities to develop hypersensitivity reactions to these molecules. Only a complete allergy work-up with a detailed analysis of the clinical history, skin tests and provocation test can show if the patient has actually experienced an allergic hypersensitivity reaction. Desensitization is to be considered as a treatment that may help patients benefit from antibiotic treatment in those cases in which they have a proven allergy to a certain molecule.

Nitrogen potential recovery and concentration of ammonia from swine manure using electrodialysis coupled with air stripping.

The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for NH(4)(+) electromigration. Total ammonia nitrogen reached 21,352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH(3) recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH(3) present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6-8.3) limited NH(3)volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH(3) form of total ammonia nitrogen.

Validation study of the s classification for melanoma patients with positive sentinel nodes: the Montreal experience.

BACKGROUND: Standard of care is to perform a complete lymph node dissection (CLND) in melanoma patients with positive sentinel lymph nodes (SLNs). However, less than 20% will have metastases in non-SLNs. The S classification was described to predict the non-SLN status, hoping to identify a subset of patients who can be spared the CLND. We tried to validate the feasibility and usefulness of this classification. MATERIALS AND METHODS: We performed a retrospective chart review. All melanoma cases between 1996 and 2006 were included, and 359 patients with SLN biopsies were identified. All pathology slides were reviewed with an emphasis on the S classification. RESULTS: There were 365 SLN biopsies performed. A total of 82 patients (22.8%) had positive SLNs, while 277 patients (77.2%) had negative SLNs. There were 22 patients classified as SI, 18 as SII, 37 as SIII, and 5 were unclassified. On CLND, only 10 patients (12.2%) had positive non-SLNs. None of these were classified as SI while 2 patients (11%) were classified as SII and 8 (22%) as SIII. The S category was found to be a predictor of non-SLN status, and this reached statistical significance (P = 0.044). On univariate analysis, only an increasing Breslow depth and ulceration were predictive of a non-SI status. CONCLUSION: Our results suggest that the S classification is easily feasible and predicts the status of non-SLNs. No patient with SI status was found to have additional non-SLN positive nodes. A larger-scale, prospective trial should be done to confirm these results and possibly spare patients the morbidity of CLND with a positive SLN.

Influence of maternal physical activity on infant's body composition.

BACKGROUND: Physical activity (PA) during pregnancy might contribute to reduce neonatal adiposity, a predictor of metabolic disturbances. OBJECTIVE: The objective of the study was to evaluate the association between maternal PA intensity and neonatal body composition. METHODS: Maternal PA measured by accelerometry and nutrition were documented during pregnancy, as well as neonatal body composition by dual-energy X-ray absorptiometry following delivery. Associations between PA at 17 and 36 weeks (time spent in moderate PA (MPA), vigorous PA (VPA) status and their interaction) and neonatal body composition were addressed by multivariate regression analyses. RESULTS: From 104 women, 50 (48%) and 16 (18%) performed VPA at 17 and 36 weeks of pregnancy. Performing VPA at either time was associated with a decreased birthweight (BW), while only VPA at 17 weeks decreased neonatal adiposity (fat percentage: -2.3 ± 0.8%, p = 0.003). MPA at 36 weeks was associated with an increased lean mass (2.0 ± 0.8 g per min day-1 , p = 0.012). Significant interactions were found for BW and bone mineral content (BMC). MPA at 17 weeks tended to increase BW, but not BMC, in the no VPA strata. By contrast, high levels of MPA (≥112 min d-1 ) combined with VPA at 17 weeks reduced neonatal BMC and BW compared with no VPA (BMC: -5.4 ± 2.0 g, p = 0.008, BW: -302.8 ± 83.7 g, p = 0.0003). Differences were not significant with low MPA levels. CONCLUSIONS: Exercise intensity modulates neonatal body composition. The long-term significance of a reduced BW, adiposity and BMC with VPA requires further study.

Ralstonia mannitolilytica in cystic fibrosis: A new predictor of worse outcomes.

BACKGROUND: Patients with Cystic Fibrosis are subject to repeated respiratory tract infections, with recent increasing isolation of unusual pathogens. Ralstonia species have lately been isolated at our institution, an organism historically frequently misidentified as Burkholderia or Pseudomonas. The prevalence of Ralstonia spp. in cystic fibrosis populations has yet to be determined, along with its clinical implications. CASE PRESENTATIONS: Seven patients out of the 301 followed at our cystic fibrosis clinic have had Ralstonia strains identified in their respiratory tract. Most strains identified were multi-drug resistant. After aquisition of Ralstonia spp., the patients' clinical course was characterized by more frequent and more severe respiratory infections along with prolonged hospitalizations, greater decline of lung function, and greater mortality. The mortality rate in this group of patients was 86%. No other factor that could explain such a dramatic evolution was identified upon review of patient data. Some of the strains involved were recognized as clones on Pulse Field Electrophoresis Gel, raising the question of person-to-person transmission. CONCLUSION: New pathogens are identified with the evolution of the microbiota in cystic fibrosis respiratory tracts. In our cohort of patients, acquisition of Ralstonia spp. was associated with dramatic outcomes in terms of disease acceleration and raised mortality rates. It is of critical importance to continue to better define the prevalence and clinical impact of Ralstonia in cystic fibrosis populations.

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.

Defective insulin-induced GLUT4 translocation in skeletal muscle of high fat-fed rats is associated with alterations in both Akt/protein kinase B and atypical protein kinase C (zeta/lambda) activities.

The cellular mechanism by which high-fat feeding induces skeletal muscle insulin resistance was investigated in the present study. Insulin-stimulated glucose transport was impaired ( approximately 40-60%) in muscles of high fat-fed rats. Muscle GLUT4 expression was significantly lower in these animals ( approximately 40%, P < 0.05) but only in type IIa-enriched muscle. Insulin stimulated the translocation of GLUT4 to both the plasma membrane and the transverse (T)-tubules in chow-fed rats. In marked contrast, GLUT4 translocation was completely abrogated in the muscle of insulin-stimulated high fat-fed rats. High-fat feeding markedly decreased insulin receptor substrate (IRS)-1-associated phosphatidylinositol (PI) 3-kinase activity but not insulin-induced tyrosine phosphorylation of the insulin receptor and IRS proteins in muscle. Impairment of PI 3-kinase function was associated with defective Akt/protein kinase B kinase activity (-40%, P < 0.01) in insulin-stimulated muscle of high fat-fed rats, despite unaltered phosphorylation (Ser473/Thr308) of the enzyme. Interestingly, basal activity of atypical protein kinase C (aPKC) was elevated in muscle of high fat-fed rats compared with chow-fed controls. Whereas insulin induced a twofold increase in aPKC kinase activity in the muscle of chow-fed rats, the hormone failed to further increase the kinase activity in high fat-fed rat muscle. In conclusion, it was found that GLUT4 translocation to both the plasma membrane and the T-tubules is impaired in the muscle of high fat-fed rats. We identified PI 3-kinase as the first step of the insulin signaling pathway to be impaired by high-fat feeding, and this was associated with alterations in both Akt and aPKC kinase activities.

Visual evoked potentials with crossed asymmetry in incomplete congenital stationary night blindness.

PURPOSE: To investigate a proposed postretinal defect in patients with the incomplete form of congenital stationary night blindness (CSNB2) and to compare visual evoked potential (VEP) results with those found in various forms of albinism. METHODS: Visual evoked potentials were performed in 10 patients with a diagnosis of CSNB2, 10 subjects with albinism, and 17 normal subjects. Visual evoked potentials were elicited monocularly with diffuse flash stimulation. Scalp electrodes were placed over each hemisphere and referred to the forehead. Interhemispheric bipolar recordings were derived, and the correlation coefficient (CC) was calculated for various segments of the interhemispheric responses. RESULTS: A crossed visual evoked potential asymmetry pattern could be demonstrated in 9 of 10 patients with CSNB2. All subjects with albinism and none of the normal subjects showed the crossed asymmetry pattern. Statistical comparison of the CC computed for various segments of the interhemispheric response shows that the pattern of inversion in CSNB2 is more prominent in the 25 to 100 msec range (median CC, -0.37) and in the 175 to 250 msec range (CC, -0.27). In subjects with albinism, all segments show a negative CC (range, -0.46 to -0.60). In normal subjects, all segments are positively correlated (range, 0.36 to 0.66). CONCLUSIONS: Crossed visual evoked potential asymmetry was found in patients with CSNB2; therefore, excessive decussation, as demonstrated by this testing procedure, should not be considered as pathognomonic for albinism.

Negative-configuration electroretinogram in Oregon eye disease. Consistent phenotype in Xp21 deletion syndrome.

OBJECTIVE: To determine whether abnormal configurations on electroretinogram were a consistent finding in patients with Xp21 deletion and to characterize the associated ophthalmologic phenotype. DESIGN: Case series. SETTING: University hospitals and eye institutes. PATIENTS: Five patients with complex glycerol kinase deficiency (Duchenne-type or Becker's muscular dystrophy, glycerol kinase deficiency, and congenital adrenal hypoplasia) and demonstrated chromosomal deletions at Xp21. Control patients were matched by age. MAIN OUTCOME MEASURES: Clinical information was obtained from medical records. Complete ophthalmologic examinations were performed. Electroretinography was performed using a Ganzfeld technique and chloral hydrate sedation. RESULTS: We report the clinical features and abnormal configurations on electroretinograms of five patients with complex glycerol kinase deficiency, including follow-up studies on a previously described patient. The original patient had ocular hypopigmentation; four, strabismus; two, myopia; three, astigmatism; and one, symptomatic night blindness. All had negative configurations on scotopic electroretinograms showing a reduced-amplitude B wave in the dark-adapted state. CONCLUSIONS: Our original report suggested a diagnosis of Aland Island eye disease, which appears to be an incomplete form of congenital stationary night blindness. Linkage data place Aland Island eye disease and congenital stationary night blindness at Xp11, whereas our patients had deletions at Xp21. The phenotype reported here may represent the effects of a single gene defect or the compound effects of the Xp21 contiguous gene syndrome (complex glycerol kinase deficiency). The phenotype is referred to as Oregon eye disease.

Development and application of a biological peptide pump for the study of the in vivo actions of angiotensin peptides.

In the past few years, a great deal of interest has been focused on the possibility that angiotensin peptides could have direct effects on target tissues independent of their hemodynamic effects. In addition, there has been much speculation on the potential biological roles of angiotensin peptides other than angiotensin II. Unfortunately, a direct test of these possibilities in whole animals has been difficult due to limitations in existing biological systems. In this review, we describe the characteristics of an engineered protein capable of directing the production of a wide variety of peptides to specific tissues and cell types in transgenic animals and discuss its potential applications.

Longitudinal study of the early electroretinographic changes in Alström's syndrome.

We obtained serial electroretinograms in four patients aged between 6 months and 5 years with Alström's syndrome and studied the early stages of the severe retinopathy that is characteristic of that disease. The weak electroretinographic signals found at age 6 months demonstrate a severe early cone dysfunction; one year later the cone activity is undetectable. The rod component of the electroretinogram is initially normal but can rapidly deteriorate to become undetectable as early as 5 years of age. These unusual electroretinographic findings are pathognomonic of Alström's syndrome and different from other cone-rod dystrophies or other syndromes with similar phenotypes such as Bardet-Biedl, Laurence-Moon, and Cohen syndromes.

Genotype/phenotype correlations in aniridia.

PURPOSE: To detect and characterize mutations in cases of familial and sporadic aniridia in Maritime Canada, and to look for indications of genotype/phenotype correlation within the cohort. METHODS: Twelve consecutive and unrelated patients (probands) who had total or nearly complete absence of irides, and four affected relatives, were recruited from Maritime Canada. Clinical data were obtained by chart review and electroretinogram testing. Mutations in the PAX6 gene were detected by single-strand conformation polymorphism and characterized by sequence analysis. RESULTS: Eleven different PAX6 mutations, 10 of which are novel, were found. The four patients with congenital cataracts all had mutations in the C-terminal proline-serine-threonine (PST)-rich domain of the PAX6 protein. Electroretinograms of nine of 11 patients displayed depressed scotopic maximum response b-wave amplitudes. The greatest decrease in b-wave amplitudes was seen in patients in whom the paired domain was disrupted by mutation. CONCLUSION: Some aspects of the phenotype of aniridia appear to correlate with the predicted effect of point mutations on the paired and PST domains of the PAX6 protein.

Effects of PAX6 mutations on retinal function: an electroretinographic study.

PURPOSE: To investigate the retinal function in aniridic patients with documented PAX6 mutations to determine the range of electroretinogram abnormalities in aniridic patients and to relate electroretinogram findings with specific PAX6 mutations. METHODS: Eleven patients with typical aniridia and fully characterized PAX6 mutations underwent electroretinography. RESULTS: In all 11 patients, electroretinogram recordings were abnormal, ranging from mild to severe. Rod-related and cone-related activities were equally affected. The amplitude of the oscillatory potentials was the most reduced, followed by the b-wave, then to a milder degree the a-wave. Mutations affecting the paired domain of the PAX6 protein had the biggest impact on the electroretinogram amplitudes. Implicit times were increased in a subgroup with mutations affecting only the homeodomain. CONCLUSION: Patients with aniridia have varying degree of retinal dysfunction, ranging from severely abnormal to almost normal. The paired domain appears to have more impact on retinal function than other regions of the PAX6 protein. It is unclear whether mutations affecting the homeodomain lead to alteration of the photoreceptor function.

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.

The electroretinographic diagnosis of the incomplete form of congenital stationary night blindness.

Fifteen patients with the incomplete form of congenital stationary night blindness (iCSNB) were reviewed to better characterize their electroretinographic (ERG) findings in view of differential diagnosis with other retinal conditions also presenting with negative bright-flash ERG responses. In all 15 patients, in dark-adapted conditions, the bright-flash ERG response had a normal a-wave followed by a subnormal b-wave. Oscillatory potentials (OPs) observed on the ascending limb of the b-wave, although delayed in implicit time, were of large amplitude. The response to a long-wavelength stimulus showed cone-related components and some well-delineated OPs. On the other hand, the photopically elicited cone responses were strongly abnormal, with a subnormal a-wave followed by a barely recordable b-wave. No OPs could be elicited under photopic conditions. The cone related components and the OP characteristics clearly distinguish iCSNB from the complete form of CSNB and other retinal conditions presenting with minimal fundus abnormalities but with negative bright-flash ERG responses, such as found in Duchenne muscular dystrophy and Aland Island eye disease. The severely abnormal post-synaptic components in the photopic recordings contrast with the well-differentiated cone activity evoked in scotopic conditions. We propose a cone system that does not respond optimally under the normal operating range (photopic) but rather under mesopic or scotopic conditions. In spite of the severe cone-ERG deficits, visual acuity was only slightly reduced. We propose that the defect, which interferes marginally with the neuronal flow of information, lies in the structures responsible for the building of the b-wave.

Correlation between electroretinogram findings and molecular analysis in the Duchenne muscular dystrophy phenotype.

Fifteen consecutive patients with the Duchenne muscular dystrophy (DMD) phenotype were studied. Each patient was asked to undergo an ophthalmic examination, an electroretinogram (ERG), and to donate a blood sample for molecular diagnosis. All 15 patients had a normal ophthalmic examination. Electroretinography was successful in 14/15 patients. The ERG tracings were normal in seven patients, abnormal in seven, and unreliable in one. Blood for molecular analysis was obtained in 12/15 patients. In the seven patients with a normal ERG, five underwent molecular analysis, and in these five no deletion was detected in the dystrophin gene. In the seven patients with an abnormal ERG, six had molecular analysis available, and all six were found to have a deletion. These results suggest that patients with a classic DMD phenotype are genetically heterogeneous, and that this heterogeneity is reflected in the ERG.

Autosomal recessive cerebellar hypoplasia and tapeto-retinal degeneration: a new syndrome.

Two sisters with autosomal recessive cerebellar hypoplasia and severe nonprogressive retinal pigmentary disease are presented. This syndrome has been previously described in only 1 patient. The retinal changes may be difficult to discern and we suggest that all patients with congenital ataxia have a detailed ophthalmologic assessment, including electroretinography.

Clonal variation in morphology, growth, physiology, anatomy and ultrastructure of container-grown white spruce somatic plants.

We assessed clonal variation in morphological variables, mineral nutrition, root growth capacity, net photosynthesis, tannin distribution, and cuticle and epicuticular wax features within four families of white spruce (Picea glauca (Moench) Voss). Seeds were collected from four families obtained through controlled crosses among selected genotypes. For each family, plants were produced either from seeds (zygotic) or by somatic embryogenesis (clones). Each family was therefore represented by its zygotic seedlings and three clones. Within a family and under similar growth conditions, several clones differed significantly from the zygotic seedlings in height, root-collar diameter, needle dry mass, branch density, shoot dry mass, root dry mass, and length of needles. Branch density (number of first-order branches per cm height) of zygotic seedlings and clones varied from 0.8 to 1.4 branches cm(-1) and from 0.6 to 1.3 branches cm(-1), respectively. Mean needle length of zygotic seedlings and clones ranged from 11 to 14 mm and from 11 to 17 mm, respectively. For many variables (height, dry mass of new roots, needle dry mass and branch density), differences among clones were significantly greater than differences among zygotic seedlings within a family. Tannins were more abundant in needles of clones than in needles of zygotic seedlings. In some clones, tannins occurred as a ribbon along the central vacuole, whereas in others they appeared as aggregates dispersed in the vacuole. Within a family, N, P and K showed considerable variations in their use efficiency. Interclonal variations were observed in root growth potential and net photosynthesis. Variations in growth and physiology reflect genetically determined differences among clones within a family.

Modulation of corticospinal excitability during imagined knee movements.

In this study, we investigated corticospinal excitability during mental simulation of a leg extension movement with the technique of transcranial magnetic stimulation. Motor evoked potentials were recorded in both knee extensors (quadriceps) and flexors (biceps femoris) in 19 trained participants (healthy volunteers). The amplitude and latency of motor evoked potentials were compared in three conditions: (1) at rest, (2) during motor imagery, and (3) at rest, immediately after motor imagery. The results showed a significant effect (p < 0.001) of conditions on motor evoked potentials amplitude in the quadriceps but not in the biceps femoris. During motor imagery, the size of motor evoked potentials in the quadriceps increased significantly (p < 0.001) compared with rest and post-imagery conditions. Changes in motor evoked potentials latency across conditions were not significant, however. These results are consistent with previous studies in the upper limb and suggest that corticospinal excitability can be enhanced during motor imagery to facilitate responses in specific lower limb muscles.

The use of binocular visual acuity in the assessment of intermittent exotropia.

BACKGROUND: It has been suggested that a decrease in distance stereoacuity in patients with intermittent exotropia is a good indicator of diminishing control. However, there has been no adequate explanation for this reported reduction in distance stereoacuity in these patients. We postulate that the decrease in stereoacuity is related to blurred visual acuity created by an increasing demand on accommodation, which these patients use in an attempt to control the exodeviation. This can best be assessed by measuring binocular visual acuity (BVA). Analysis of BVA could provide a useful clinical tool to evaluate control measures used by patients with intermittent exotropia. METHODS: A prospective study of patients with intermittent exotropia, ranging in age from 6 to 60 years, was performed. Only those patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study. The data analysis included the age of these patients, age at onset of the deviation, monocular and binocular visual acuity, oculomotor and fusional status, and near and distance stereoacuity. RESULTS: Data from 36 patients show that the measurements of BVA correlated well with a corresponding loss of distance stereoacuity but not with the size of the deviation. CONCLUSION: The decrease of stereoacuity reported in patients with exotropia can be explained by increased accommodation and decreased distance BVA. This measurement can be a simple method of quantifying the fusional control of patients with intermittent exotropia.