Alessandro Porro

Hyper-IgE syndrome: dental implications

Hyper-IgE syndrome (HIES) is a rare multisystem disorder with both immunologic and nonimmunological features. It is characterized by extremely elevated IgE serum levels, eczema, and recurrent skin and pulmonary infections. Dental anomalies are often included, such as retention of deciduous teeth together with ectopic eruption or noneruption of permanent teeth. Severe susceptibility to caries and mycotic infections, insufficient transversal diameter of the palate, mucosal plaques, and fissures typically located on the tongue and on the palate are often present. The aim of this study was to review the literature and to report a 6-year observation of 6 patients with HIES (aged 8-39 years) with focus on their oral problems and the treatment provided. The importance of the role of the dentist both in early diagnosis of this syndrome and in monitoring oral conditions was stressed. The dentist can prevent infective complications and intercept the development of malocclusion with a reduction of the need for complex treatment.

Fusicoccin Activates KAT1 Channels by Stabilizing Their Interaction with 14-3-3 Proteins.

The phytotoxin fusicoccin stabilizes the interaction between KAT1 channels and their regulatory protein 14-3-3, leading to an increase in the number and in the activity of the channels. Plants acquire potassium (K+) ions for cell growth and movement via regulated diffusion through K+ channels. Here, we present crystallographic and functional data showing that the K+ inward rectifier KAT1 (K+ Arabidopsis thaliana 1) channel is regulated by 14-3-3 proteins and further modulated by the phytotoxin fusicoccin, in analogy to the H+-ATPase. We identified a 14-3-3 mode III binding site at the very C terminus of KAT1 and cocrystallized it with tobacco (Nicotiana tabacum) 14-3-3 proteins to describe the protein complex at atomic detail. Validation of this interaction by electrophysiology shows that 14-3-3 binding augments KAT1 conductance by increasing the maximal current and by positively shifting the voltage dependency of gating. Fusicoccin potentiates the 14-3-3 effect on KAT1 activity by stabilizing their interaction. Crystal structure of the ternary complex reveals a noncanonical binding site for the toxin that adopts a novel conformation. The structural insights underscore the adaptability of fusicoccin, predicting more potential targets than so far anticipated. The data further advocate a common mechanism of regulation of the proton pump and a potassium channel, two essential elements in K+ uptake in plant cells.

A synthetic peptide that prevents cAMP regulation in mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels

Binding of TRIP8b to the cyclic nucleotide binding domain (CNBD) of mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels prevents their regulation by cAMP. Since TRIP8b is expressed exclusively in the brain, we envisage that it can be used for orthogonal control of HCN channels beyond the central nervous system. To this end, we have identified by rational design a 40-aa long peptide (TRIP8bnano) that recapitulates affinity and gating effects of TRIP8b in HCN isoforms (hHCN1, mHCN2, rbHCN4) and in the cardiac current If in rabbit and mouse sinoatrial node cardiomyocytes. Guided by an NMR-derived structural model that identifies the key molecular interactions between TRIP8bnano and the HCN CNBD, we further designed a cell-penetrating peptide (TAT-TRIP8bnano) which successfully prevented β-adrenergic activation of mouse If leaving the stimulation of the L-type calcium current (ICaL) unaffected. TRIP8bnano represents a novel approach to selectively control HCN activation, which yields the promise of a more targeted pharmacology compared to pore blockers.

Phenotypic Spectrum of HCN4 Mutations: A Clinical Case

The hyperpolarization-activated cyclic nucleotide-gated (HCN) cation (Na+/K+) currents (If/Ih) are generated by 4 members of the channel family (HCN1–4).1 These currents contribute to the pacemaker function2 in heart and brain.3 The HCN4 current is known to play a crucial role in the automaticity of the sinus node through the generation of a slow diastolic depolarization during the phase 4 of the cardiac action potential.4 Thus, it is a crucial channel for appropriate pacemaker activity and conduction system function because it facilitates rapid repolarization. Interestingly, HCN4 has been shown to be expressed in essentially the entire heart tissue.5 Mutations in HCN4 have been associated mainly with sick sinus syndrome phenotype6; however, in recent years, a broad spectrum of phenotypes has been reported, including sinus bradycardia,7 inappropriate sinus tachycardia,8 early-onset atrial fibrillation,9,10 atrio-ventricular block,11,12 idiopathic ventricular tachycardia,13 left ventricular noncompaction (LVNC),14–17 dilation of the aorta, and mood and anxiety disorders.19 In the present study, we report a case with sick sinus syndrome, LVNC, mood and anxiety disorders, and ventricular fibrillation (VF) hosting 2 novel HCN4 -pore mutations.nnThe index patient was a 36-year-old man, who presented initially with mood and anxiety disorders characterized by important depressive episodes. Previous clinical records revealed a slightly impaired left ventricular function, paroxysmal atrial fibrillation, frequent premature ventricular complexes, and nonsustained tachycardia originating from the right ventricle. Therapy with β-blocker was initiated but discontinued shortly because of profound sinus bradycardia, which did not resume after washout. A cardiac magnetic resonance imaging excluded a right ventricular cardiomyopathy. The left ventricle showed an uncommon hypertrabeculation; however, the criteria for an LVNC were not fulfilled at that time.nnEight years later, the patient was hospitalized because of heart failure and …

Water and the city of Milan at the end of the nineteenth century

Abstract Since the Middle Ages Milan obtained its water supply satisfactorily from shallow wells. Significant problems developed during the nineteenth century, however, prompting the Lombard Institute to announce the Cagnola Award for a three-year study project to analyse the water both chemically and physically and to remedy the problem of pollution. The award was made to Angelo Pavesi (1830–96), a chemist, and Ermenegildo Rotondi (1845–1915), a civil engineer. They concluded that cemetery wastewater should be prevented from entering the city and that the number of deep artesian wells should be increased. Some years later, another problem regarding hygiene and water supply arose and it seemed doubtful whether the principal hospital of the city could fulfil the new hygiene requirements. Pietro Canetta (1836–1903) studied the records of the main hospitals water supply and disposal from 1457, demonstrating that it could be regarded as a model for the supply of good-quality water and for wastewater disposal without polluting the city. Since 1906 all of Milans drinking water has been derived from groundwater; untreated wastewater continued to be discharged into rivers until 2004 but since then all water has been treated.

Structure-guided design of a cell penetrating peptide preventing cAMP modulation of HCN channels

The auxiliary subunit TRIP8b prevents cAMP activation of HCN channels by antagonizing its binding to their cyclic-nucleotide binding domain (CNBD). By determining an NMR-derived structure of the complex formed by the HCN2 channel CNBD and a minimal TRIP8b fragment, TRIPnano, we show here a bipartite interaction between the peptide and CNBD which prevents cAMP binding in two ways: through direct competition for binding at the distal C-helix of the CNBD; and through an allosteric reduction in cAMP affinity induced by TRIP8b binding to the CNBD N-bundle loop. TRIPnano abolishes cAMP binding in all three isoforms, HCN1, HCN2 and HCN4 and can be used to prevent cAMP stimulation in native f-channels. Application of TRIP8bnano, or its delivery via a cell-penetrating sequence, in sinoatrial node myocytes, selectively inhibits beta-adrenergic stimulation of the native If current and mimics the physiological concentrations of acetylcholine leading to a 30% reduction in the spontaneus rate of action potential firing.

A light-gated potassium channel for sustained neuronal inhibition

Currently available inhibitory optogenetic tools provide short and transient silencing of neurons, but they cannot provide long-lasting inhibition because of the requirement for high light intensities. Here we present an optimized blue-light-sensitive synthetic potassium channel, BLINK2, which showed good expression in neurons in three species. The channel is activated by illumination with low doses of blue light, and in our experiments it remained active over (tens of) minutes in the dark after the illumination was stopped. This activation caused long periods of inhibition of neuronal firing in ex vivo recordings of mouse neurons and impaired motor neuron response in zebrafish in vivo. As a proof-of-concept application, we demonstrated that in a freely moving rat model of neuropathic pain, the activation of a small number of BLINK2 channels caused a long-lasting (>30u2009min) reduction in pain sensation.BLINK2 is a light-activated potassium channel for optogenetic inhibition of neuronal activity. Alberio et al. apply the tool in systems as diverse as cultured rat neurons, mouse brain slices, behaving zebrafish and a rat model of neuropathic pain.

La valutazione schermografica delle pneumoconiosi (1941-1948): il ruolo della Clinica del Lavoro di Milano/Miniature chest radiographs and pneumoconiosis at Clinica del Lavoro in Milan (1941-1948)

Since the end of the 19th century, X-rays have been used to detect lung diseases. In Italy, 207,096 miniature chest radiographs were taken from 1941 to 1948. Traditional radiographs gave better results, but miniature chest radiographs were useful for screening. Indeed, the development of mobile miniature chest radiography units resulted in an improvement in mass X-rays screening for the detection of penumoconiosis. These mobile miniature units were mounted on a bus chassis, a solution that allowed to easily reach workers. The authors analyze some models of X-ray wagon units used by the Clinica del Lavoro in Milan in the 1950s. From the point of view of medical museology, the preservation of these devices requires appropriate spaces.

HCN1 mutation spectrum: from neonatal epileptic encephalopathy to benign generalized epilepsy and beyond

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels control neuronal excitability and their dysfunction has been linked to epileptogenesis but few individuals with neurological disorders related to variants altering HCN channels have been reported so far. In 2014, we described five individuals with epileptic encephalopathy due to de novo HCN1 variants. To delineate HCN1-related disorders and investigate genotype-phenotype correlations further, we assembled a cohort of 33 unpublished patients with novel pathogenic or likely pathogenic variants: 19 probands carrying 14 different de novo mutations and four families with dominantly inherited variants segregating with epilepsy in 14 individuals, but not penetrant in six additional individuals. Sporadic patients had epilepsy with median onset at age 7 months and in 36% the first seizure occurred during a febrile illness. Overall, considering familial and sporadic patients, the predominant phenotypes were mild, including genetic generalized epilepsies and genetic epilepsy with febrile seizures plus (GEFS+) spectrum. About 20% manifested neonatal/infantile onset otherwise unclassified epileptic encephalopathy. The study also included eight patients with variants of unknown significance: one adopted patient had two HCN1 variants, four probands had intellectual disability without seizures, and three individuals had missense variants inherited from an asymptomatic parent. Of the 18 novel pathogenic missense variants identified, 12 were associated with severe phenotypes and clustered within or close to transmembrane domains, while variants segregating with milder phenotypes were located outside transmembrane domains, in the intracellular N- and C-terminal parts of the channel. Five recurrent variants were associated with similar phenotypes. Using whole-cell patch-clamp, we showed that the impact of 12 selected variants ranged from complete loss-of-function to significant shifts in activation kinetics and/or voltage dependence. Functional analysis of three different substitutions altering Gly391 revealed that these variants had different consequences on channel biophysical properties. The Gly391Asp variant, associated with the most severe, neonatal phenotype, also had the most severe impact on channel function. Molecular dynamics simulation on channel structure showed that homotetramers were not conducting ions because the permeation path was blocked by cation(s) strongly complexed to the Asp residue, whereas heterotetramers showed an instantaneous current component possibly linked to deformation of the channel pore. In conclusion, our results considerably expand the clinical spectrum related to HCN1 variants to include common generalized epilepsy phenotypes and further illustrate how HCN1 has a pivotal function in brain development and control of neuronal excitability.

Per un’ergobiografia di Marcello Cesa-Bianchi

Si presenta, preceduta da una sintesi introduttiva riguardo alla vita personale e accademica, la vasta produzione scientifica del Prof. Marcello Cesa-Bianchi. Si tratta di quasi settant’anni di ricerca e di pubblicazioni. Svariati temi della psicologia sono stati sviluppati e approfonditi. Non vi e argomento che non sia rappresentato. Il lavoro del prof. Cesa-Bianchi costituisce una testimonianza e un patrimonio culturale e accademico di immenso valore storico, ma anche di prospettiva, sia per gli attuali e continui contributi scientifici sia per gli sviluppi che le sue ricerche possono sempre offrire, indipendentemente dalla loro data di pubblicazione.