How to recognize the order of infinitesimal mechanisms: A numerical approach

Structures presenting kinematical inderterminacy are usually called mechanisms. This paper is entirely concerned with assemblies which reveal themselves to be mechanisms at a null value of the load. Among them a first distinction is made between infinitesimal and finite ones, the former being characterized by one or several directions of lower (but not zero) stiffness, whereas the latter show at least one finite admissible displacement for which none of the bars undergoes any elongation. Moreover, there exists the possibility to make a further distinction among the infinitesimal mechanisms, according to which is the order of the stiffness along the direction considered above. The way of evaluating this order is to perform a local analysis of the strain energy of the assembly, once the displacement field is parametrized in terms of a suitable parameter. By means of a finite element technique, this analysis can be easily performed through the numerical approach presented in this report.     

In-vitro iron dialysability from legumes: Influence of phytate and extrusion cooking

In-vitro iron dialysability from five Italian legumes (mottled bean, white bean, faba bean, chickpea, lentil) and the influence of phytate and extrusion cooking on it were evaluated. Iron dialysability was 2·3 and 2·4% in mottled and white bean respectively, 1·2% infaba bean, 2·7% in chickpea and 1·1% in lentil. After extrusion cooking the flours showed a marked iron contamination and a decrease in iron dialysability, but these changes were significant only for mottled bean. Enzymic phytate removal induced an increase in iron dialysability > 100% in all the raw legumes except mottled bean which showed an increase of only 57%. This finding indicates that, although phytate consistently modifies iron dialysability, it is difficult to identify a quantitative relationship between phytate content and iron dialysability.     

Novel KCND3 Variant Underlying Nonprogressive Congenital Ataxia or SCA19/22 Disrupt KV4.3 Protein Expression and K+ Currents with Variable Effects on Channel Properties

KCND3 encodes the voltage-gated potassium channel K_V4.3 that is highly expressed in the cerebellum, where it regulates dendritic excitability and calcium influx. Loss-of-function K_V4.3 mutations have been associated with dominant spinocerebellar ataxia (SCA19/22). By targeted NGS sequencing, we identified two novel KCND3 missense variants of the K_V4.3 channel: p.S347W identified in a patient with adult-onset pure cerebellar syndrome and p.W359G detected in a child with congenital nonprogressive ataxia. Neuroimaging showed mild cerebellar atrophy in both patients. We performed a two-electrode voltage-clamp recording of K_V4.3 currents in Xenopus oocytes: both the p.G345V (previously reported in a SCA19/22 family) and p.S347W mutants exhibited reduced peak currents by 50%, while no K+ current was detectable for the p.W359G mutant. We assessed the effect of the mutations on channel gating by measuring steady-state voltage-dependent activation and inactivation properties: no significant alterations were detected in p.G345V and p.S347W disease-associated variants, compared to controls. K_V4.3 expression studies in HEK293T cells showed 53% (p.G345V), 45% (p.S347W) and 75% (p.W359G) reductions in mutant protein levels compared with the wildtype. The present study broadens the spectrum of the known phenotypes and identifies additional variants for KCND3-related disorders, outlining the importance of SCA gene screening in early-onset and congenital ataxia.     

Total Heme and Non-heme Iron in Raw and Cooked Meats

ABSTRACT: This study provides data on the total heme and non-heme iron contents in poultry (chicken, turkey), beef, veal, lamb, horse, ostrich, rabbit, and pork meat cuts. The effect of cooking on heme iron content was also studied. Total iron and heme iron contents markedly differed between muscles in poultry. Heme iron in red meats ranged from 72 to 87%. Heme iron in rabbit and pork was 56 and 62% of total iron. Heating decreased heme iron, the severity of the losses depended on cooking methods: in poultry, losses ranged from 22 to 43%; less severe impact was detected in pan-cooked meat, where the losses ranged from 1 to 24%.     

Superior Cerebellar Atrophy: An Imaging Clue to Diagnose ITPR1-Related Disorders

The inositol 1,4,5-triphosphate receptor type 1 (ITPR1) gene encodes an InsP₃-gated calcium channel that modulates intracellular Ca²⁺ release and is particularly expressed in cerebellar Purkinje cells. Pathogenic variants in the ITPR1 gene are associated with different types of autosomal dominant spinocerebellar ataxia: SCA15 (adult onset), SCA29 (early-onset), and Gillespie syndrome. Cerebellar atrophy/hypoplasia is invariably detected, but a recognizable neuroradiological pattern has not been identified yet. With the aim of describing ITPR1-related neuroimaging findings, the brain MRI of 14 patients with ITPR1 variants (11 SCA29, 1 SCA15, and 2 Gillespie) were reviewed by expert neuroradiologists. To further evaluate the role of superior vermian and hemispheric cerebellar atrophy as a clue for the diagnosis of ITPR1-related conditions, the ITPR1 gene was sequenced in 5 patients with similar MRI pattern, detecting pathogenic variants in 4 of them. Considering the whole cohort, a distinctive neuroradiological pattern consisting in superior vermian and hemispheric cerebellar atrophy was identified in 83% patients with causative ITPR1 variants, suggesting this MRI finding could represent a hallmark for ITPR1-related disorders.     

A Novel KCNA2 Variant in a Patient with Non-Progressive Congenital Ataxia and Epilepsy: Functional Characterization and Sensitivity to 4-Aminopyridine

Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patch-clamp. In silico analysis supported the electrophysiological data. E236K channels showed voltage-dependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain- and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies.     

Effect of cooking on availability and in vitro nitrosation of precursors of volatile N-nitroso compounds in seafood

Aqueous extracts of uncooked and cooked samples of squid and shrimp, characterized by their high amine content, were exposed to nitrate. The samples were cooked following traditional Italian recipes: stewing, grilling and deep-frying for squid; boiling, grilling and deep-frying for shrimp. Incubation of the aqueous extracts with nitrite in acidic medium yielded appreciable amounts of N-nitrosodimethylamine. Ascorbic acid and alpha-tocopherol were effective in preventing nitrosation of seafood amines only in the presence of molar excesses of these vitamins. An attempt at modulating nitrosation through the use of food ingredients naturally rich in vitamin C was unsuccessful.