Mitochondrial Alpha-Keto Acid Dehydrogenase Complexes: Recent Developments on Structure and Function in Health and Disease.

The present work delves into the enigmatic world of mitochondrial alpha-keto acid dehydrogenase complexes discussing their metabolic significance, enzymatic operation, moonlighting activities, and pathological relevance with links to underlying structural features. This ubiquitous family of related but diverse multienzyme complexes is involved in carbohydrate metabolism (pyruvate dehydrogenase complex), the citric acid cycle (α-ketoglutarate dehydrogenase complex), and amino acid catabolism (branched-chain α-keto acid dehydrogenase complex, α-ketoadipate dehydrogenase complex); the complexes all function at strategic points and also participate in regulation in these metabolic pathways. These systems are among the largest multienzyme complexes with at times more than 100 protein chains and weights ranging up to ~10 million Daltons.

[Introduction of fiberoptic endoscopic evaluation of swallowing and increase of the range of indications in our department].

Dysphagia is a disease resulting from preparatory or transport disorder of the swallowing process and it is divided into oropharyngeal and esophageal phases according to the site of the lesion. The ear, nose and throat assessment focuses on the oropharyngeal phase, but differential diagnosis, investigation, and treatment of the cause of dysphagia is often a complex task requiring multidisciplinary approach and collaboration. The method of fiberoptic endoscopic evaluation of swallowing (FEES) has been introduced at the Department of Ear, Nose and Throat and Head-Neck Surgery, University of Szeged, enabling the examination of otorhinolaryngological and neurological disorders of swallowing as well as objective analysis of patients' swallowing quality.

Extended partial laryngectomy with functional preservation using the rotational crico-thyrotracheopexy.

Objectives: Glottic tumors with infiltration of the anterior/posterior commissure, and lesions with subglottic, cricoid, or cricoarytenoid joint infiltration have been highly controversial in the past, from the perspective of oncological safety. Although conservation laryngeal resection options exist, most are limited by the extent of resection proscribed by the technique and the postoperative functional results. Oncologically speaking, extended vertical hemilaryngectomy is often the optimal solution.

Defective function of α-ketoglutarate dehydrogenase exacerbates mitochondrial ATP deficits during complex I deficiency.

The NDUFS4 knockout (KO) mouse phenotype resembles the human Complex I deficiency Leigh Syndrome. The irreversible succination of protein thiols by fumarate is increased in select regions of the NDUFS4 KO brain affected by neurodegeneration. We report that dihydrolipoyllysine-residue succinyltransferase (DLST), a component of the α-ketoglutarate dehydrogenase complex (KGDHC) of the tricarboxylic acid (TCA) cycle, is succinated in the affected regions of the NDUFS4 KO brain.

Structural and Biochemical Investigation of Selected Pathogenic Mutants of the Human Dihydrolipoamide Dehydrogenase.

Clinically relevant disease-causing variants of the human dihydrolipoamide dehydrogenase (hLADH, hE3), a common component of the mitochondrial α-keto acid dehydrogenase complexes, were characterized using a multipronged approach to unravel the molecular pathomechanisms that underlie hLADH deficiency. The G101del and M326V substitutions both reduced the protein stability and triggered the disassembly of the functional/obligate hLADH homodimer and significant FAD losses, which altogether eventually manifested in a virtually undetectable catalytic activity in both cases. The I12T-hLADH variant proved also to be quite unstable, but managed to retain the dimeric enzyme form; the LADH activity, both in the and catalytic directions and the affinity for the prosthetic group FAD were both significantly compromised.