ABSTRACT
The process of freezing biological material at extremely low temperatures is known as cryopreservation. To ensure the preservation of cells and tissues over an extended period of time, low temperatures are applied since biological processes, including the biochemical ones, come to a halt under cryogenic conditions and thus it is possible to maintain their structural and functional integrity. The field of cryopreservation gained more prominence in the 20th century and emerged as an unavoidable technology for different applications such as cell therapy, tissue engineering, or assisted fertilization. In this work we provide an overview of various technologies in the field of cryotechnology with regard to the freezing, storage and thawing of living cells. The first part covers the freezing process, starting with cryoprotective agents regarding their protection mechanisms and compositions, passing by cryo-imaging, micro-fluidic systems, and the currently available freezing and biobanking equipment. The second part focusses on the thawing process as well as the hypothermic preservation for the short-term storage of biological materials and constructs. Doi.org/10.54680/fr23610110112.
Subject(s)
Biological Specimen Banks , Cryopreservation , Cryopreservation/methods , Cryoprotective Agents/pharmacology , Freezing , TechnologyABSTRACT
Nicotinic ACh (acetylcholine) and 5-HT3 (5-hydroxytryptamine type-3) receptors are cation-selective ion channels of the Cys-loop transmitter-gated ion channel superfamily. Numerous lines of evidence indicate that the channel lining domain of such receptors is formed by the alpha-helical M2 domain (second transmembrane domain) contributed by each of five subunits present within the receptor complex. Specific amino acid residues within the M2 domain have accordingly been demonstrated to influence both single-channel conductance (gamma) and ion selectivity. However, it is now clear from work performed on the homomeric 5-HT3A receptor, heteromeric 5-HT3A/5-HT3B receptor and 5-HT3A/5-HT3B receptor subunit chimaeric constructs that an additional major determinant of gamma resides within a cytoplasmic domain of the receptor termed the MA-stretch (membrane-associated stretch). The MA-stretch, within the M3-M4 loop, is not traditionally thought to be implicated in ion permeation and selection. Here, we describe how such observations extend to a representative neuronal nicotinic ACh receptor composed of alpha4 and beta2 subunits and, by inference, probably other members of the Cys-loop family. In addition, we will attempt to interpret our results within the context of a recently developed atomic scale model of the nicotinic ACh receptor of Torpedo marmorata (marbled electric ray).
Subject(s)
Receptors, Nicotinic/chemistry , Receptors, Serotonin, 5-HT3/chemistry , Amino Acid Sequence , Animals , Humans , Models, Molecular , Molecular Sequence Data , Mutation , Protein Conformation , Protein Subunits , Receptors, Nicotinic/genetics , Receptors, Serotonin, 5-HT3/genetics , Sequence Alignment , Sequence Homology, Amino AcidABSTRACT
Fifty four patients presenting by huge splenomegaly were admitted to Tropical Medicine Department, El-Minia University Hospital. Tissue biopsy revealed pure bilharziasis due to S. hematobium in 10 (19%) cases, liver cirrhosis in 23 (42%), mixed schistosomiasis and cirrhosis in 8 (15%), hepatoma in 3 (6%), lymphoma in 6 (11%) and hematological diseases in the form of chronic myeloid leukemia in 2 (3.5%) and thalassemia major in 2 (3.5%) cases. The sensitivity and specificity of abdominal ultrasonography was 100% and 97% in cases of schistosomiasis, 100% and 100% in cases of hepatoma, 87% and 100% in cases of liver cirrhosis, 33% and 100% in cases of lymphoma respectively. There was a positive significant correlation between endoscopic variceal grading, portal vein diameter, splenic vein diameter, size of the spleen and the grading of the portal tract thickenings. The pathological and ultrasonographic diagnosis was the same in 38 (70%) cases. Splenogram was characteristic but not diagnostic in cases of schistosomiasis and liver cirrhosis. It was diagnostic and similar to peripheral blood picture in the 2 cases of chronic myeloid leukemia and was normal in cases of thalassemia major. Splenic aspiration was able to diagnose all cases of lymphomas. It can be considered as a useful adjunct to the usual diagnostic procedures, both in staging and follow up, especially in cases presenting only by splenomegaly.
