Sural nerve involvement in Guillain-Barré syndrome: Clinical and prognostic implications. A prospective cohort.

BACKGROUND: Sural sparing is common in Guillain-Barré syndrome (GBS). However, one third of patients have sural nerve compromise. Its clinical implications associated factors and short-term prognosis are still unknown. The objective of this study is to identify if sural nerve compromise is associated with a worse prognosis and to describe clinical and electrophysiological characteristics in Guillain-Barré syndrome. MATERIALS AND METHODS: We prospectively analyzed patients with Guillain-Barré diagnosis with vs without sural nerve compromise. All patients underwent nerve conduction studies within the first 3 days of hospital admission. Clinical and electrophysiological characteristics were compared between groups. RESULTS: 174 patients were included in this study. Acute inflammatory demyelinating polyneuropathy was the predominant variant (43.7 %). Thirty percent of patients had sural nerve involvement. In the comparative analysis between affected vs unaffected sural groups, age ≥50 years and Guillain-Barré disability score ≥3 demonstrated a statistically significant difference. Regarding short-term recovery period for independent walking, there was no significant difference. In the multivariate analysis, age ≥50 years was identified as independent factors for sural nerve compromise on admission. CONCLUSION: sural nerve compromise occurs in 30 % of patients with GBS and is not associated with a worse functional prognosis. Age ≥50 years was identified as an independent factor for sural nerve compromise.

Short-Communication: Variable Expression of Clinical Symptoms and an Unexpected Finding of Vacuolar Myopathy Related to a Pathogenic Variant in the CACNA1S Gene in a Previous Case Report.

Several clinical phenotypes have been described related to the CACNA1S gene (calcium channel voltage-dependent L-type alpha-1S subunit), such as autosomal dominant hypokalemic periodic paralysis 1 and autosomal dominant malignant hyperthermia susceptibility and are associated with autosomal dominant and recessive congenital myopathy. Recently, an interesting case of a 58-year-old male patient was published describing an unusual clinical presentation of hypokalemic periodic paralysis where a late-onset limb-girdle myopathy had developed 41 years after paralysis occurred when the patient was 11 years old. Muscle biopsy results were consistent with myopathic changes and revealed the presence of vacuoles, without inflammatory reaction. Later, molecular analysis revealed a pathogenic variant c.3716G>A (p.Arg1239His) in exon 30 of the CACNA1S gene. This technical report provides an extension of the molecular findings and evaluates the clinical and histopathological relationship previously published regarding this case.

Vacuolar Myopathy Associated to CACNA1S Mutation as a Rare Cause of Late-Onset Limb-Girdle Myopathy: A Case Report.

Late-onset limb-girdle myopathies pose a diagnostic challenge. The most common etiologies are inflammatory, followed by genetic and metabolic. Rare cases include limb-girdle dystrophies and permanent myopathies (vacuolar), such as those associated with hypokalemic periodic paralysis (HypoPP). We present the case of a 59-year-old male who initiated with episodic acute severe weakness when he was 11, during which serum potassium levels of <2.5 meq/L were revealed during workup. Potassium reposition reversed these episodes. They occurred every three to five years, and the last episode was five years prior to the current illness. When he was 58, he presented progressive pelvic girdle weakness. On examination, he presented decreased strength in the iliopsoas and quadriceps. The laboratory results showed mildly elevated creatine kinase. Muscle biopsy revealed a vacuolar myopathy, and genetic testing identified a pathogenic variant in the CACNA1S gene, locus 1q32.1 [c.3716G> A (p.Arg1239His), heterozygous state].

Is genetic structure of the southern pygmy mouse Baiomys musculus (Cricetidae) related to human-induced spatial landscape heterogeneity in a tropical dry forest?

Tropical dry forests are biologically important biomes sustaining a high rate of endemic species. However, these forests are highly threatened by human activities that negatively impact them on distinct levels, including the genetic diversity. Within the framework of landscape genetics (that seeks to evaluate the relation of characteristics of the environmental matrix with population genetics), we used ISSR markers to evaluate the relationship between the alteration of tropical dry forest by human-induced activities (conserved vs. disturbed) with the genetic structure of four breeding sites of the southern pygmy mouse Baiomys musculus. Averaging among the 105 loci used, the unbiased heterozygosis per population (0.247-0.305) was statistically similar among the four sites, as well as between conserved and disturbed conditions (2-way ANOVA F ((3,16)) = 1.47, P = 0.1984). The genetic differentiation among the four breeding sites was high (F (ST) = 0.1122; 95 % CI 0.082-0.146) considering the geographical scale evaluated (ca. 4 km). Both, a factorial correspondence analysis and a model-based clustering analysis showed the existence of four genetic groups (one per breeding site). However, no association of genetic structure with disturbance conditions was revealed by these analyses. The absence of differences in mean genetic diversity and the lack of association of genetic structure with habitat transformation suggest that B. musculus has enough behavioral plasticity and enough genetic diversity to respond to environmental heterogeneity caused by human activities. We discussed conditions in which habitat transformation could indeed favor B. musculus.

Genetic structure of the carnivorous plant Pinguicula moranensis (Lentibulariaceae) on the transvolcanic Mexican belt.

Most species of Pinguicula present a montane distribution with populations located at high altitudes. In this context, we proposed that populations of Pinguicula species could be genetically differentiated even at a local scale. This study supported that prediction, as a RAPD-based analysis of molecular variance revealed a high degree of genetic structure (Φ (st) = 0.157, P = 0.001) and low gene flow (Nm = 1.0) among four central populations of Pinguicula moranensis in Mexico, with a maximum geographic separation of about 140 km. The four populations also exhibited high levels of genetic diversity (mean Nei's genetic diversity = 0.3716; % polymorphism = 95.45%). The evolutionary implications of the genetic structure found in P. moranensis for other species in the genus are discussed in the context of the naturally fragmented distribution and a set of life history traits shared by most Pinguicula species that could promote geographic isolation and limited gene flow.

Patterns of prey capture and prey availability among populations of the carnivorous plant Pinguicula moranensis (Lentibulariaceae) along an environmental gradient.

In this study we explored the effect of the physical environment and the availability of prey (biomass and taxonomic composition) on the patterns of prey capture and reproduction on five populations of Pinguicula moranensis (Lentibulariaceae) in areas ranging from pine-oak forests to desert scrublands. Environmental variation was summarized using principal factor analysis. Prey availability and prey capture increased toward the shadiest, most humid, and fertile population. The probability of reproduction and average bud production per population did not follow the same tendency because both fitness components peaked at the middle of the environmental gradient. These results suggest that the benefits derived from carnivory are maximized at sites fulfilling a trade-off between light, moisture, and prey availability. We also found that the taxonomic composition of both the available prey and that of the prey captured by plants varied among populations. The results also indicated that the prey captured by plants are not a random sample of prey available within populations. Overall, the results from this study revealed a marked amount of heterogeneity in the physical and biotic environment among the populations of P. moranensis, which has the potential to affect the outcome of the interaction between this carnivorous species and its prey.