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The Severe Combined Immunodeficiency (scid) Mutation, Chromosome 16
Published in John P. Sundberg, Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
John P. Sundberg, Leonard D. Shultz
Severe combined immunodeficiency occurs in humans as an autosomal recessive trait3,4 or X-linked characteristic4 that is clinically very similar to the mouse scid mutation. Recently, Schwartz et al.19 described five human patients with impaired rearrangement processes at the JH region analogous to the defect in scid/scid mice. Human severe combined immune deficiency may also be associated with a deficiency of adenosine deaminase.2,3 As with scid/scidmice, if human patients are not protected from environmental pathogens, they will die as a result of bacterial, viral, and/or mycotic infections.20
Purine nucleoside phosphorylase deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
Definitive treatment can be achieved by means of bone marrow transplantation. Transfusion therapy was developed in the management of patients with adenosine deaminase deficiency [34]. In PNP, deficiency transfusion therapy has variously been reported to produce partial improvement or no improvement in immune function [35–38]. In an extensive experience with 100 weeks of erythrocyte transfusion therapy in a boy with PNP deficiency, there was a correction of the elevated level of dGTP in erythrocytes and leukocytes, as well as a substantial increase in serum concentrations of urate and decrease in urinary nucleoside content [7]. The immunologic abnormality was partially reversed. However, the overall results of therapy in this disease have been much less effective than in adenosine deaminase deficiency [39].
Overview of the mucosal immune system structure
Published in Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald, Principles of Mucosal Immunology, 2020
Reinhard Pabst, Per Brandtzaeg
The switch process requires a variety of transcription factors and enzymatic activity expressed by cell type–specific and more generalized DNA repair enzymes, particularly activation-induced cytidine deaminase (AID, see Figure 1.6). AID is present during class-switch recombination and may link class-switch recombination to somatic hypermutation of Ig V-gene segments, which takes place during the germinal center reaction (see Chapter 8). AID-deficient mice show dramatic hyperplasia of isolated lymphoid follicles in response to intestinal overgrowth of the indigenous microbiota, similar to the lymphoid hyperplasia that occurs in people with immunoglobulin deficiency who often are infected with the parasite Giardia lamblia. This could reflect an inadequate compensatory antibody repertoire in the gut due to lack of somatic hypermutation in the SIgM that partially replaces SIgA in these mice.
Recent advances in delivering RNA-based therapeutics to mitochondria
Published in Expert Opinion on Biological Therapy, 2022
Yuma Yamada, Sen Ishizuka, Manae Arai, Minako Maruyama, Hideyoshi Harashima
The DddA-derived cytosine base editor (DdCBE) is described as a method for base editing of mutated mtDNA to convert it into wild-type mtDNA. A double-stranded DNA deaminase toxin A (DddA), which is a cytidine deaminase that catalyzes the conversion of cytosine (C) to uracil (U), was recently discovered. A unique feature of DddA is that it targets double-stranded DNA. Since conventional cytidine deaminases operate on single-stranded nucleic acids, their use in base editing requires the unwinding of the double-stranded DNA (dsDNA). This made it difficult to use for mitochondrial genome editing, where it is difficult to deliver nucleic acids such as gRNA to mitochondria. However, DddA binds to dsDNA and does not require the unwinding of dsDNA for cytosine base editing. Therefore, if DddA could be directed to mtDNA targets using dsDNA-binding proteins such as ZFN and TALE, specific mtDNA base editing would be possible.
Shaddock (Citrus maxima) peels extract restores cognitive function, cholinergic and purinergic enzyme systems in scopolamine-induced amnesic rats
Published in Drug and Chemical Toxicology, 2022
Ayokunle O. Ademosun, Adeniyi A. Adebayo, Temitope V. Popoola, Ganiyu Oboh
Adenosine deaminase (ADA) catalyzes the irreversible removal of amine group from adenosine to form inosine. In the purinergic system, ADA serves as an important point of regulation of adenosine level, a purine nucleoside that mediates diverse physiological conditions. Adenosine has been reported to play a neuromodulatory role in the CNS in mammals (Burnstock 2006, Burnstock et al.2011). In this study, it was observed that scopolamine administration increased the activity of ADA, and this effect was prevented by treatment with shaddock peels extract or donepezil. An increase in ADA activity increases the hydrolysis of adenosine to inosine. Thus, the effect of scopolamine on this enzyme leads to increased removal of extracellular adenosine decreasing its levels, which may lead to impairment of the adenosinergic neurotransmission. The depletion of extracellular adenosine can disrupt memory formation since adenosine has been reported as an important neuromodulator in synaptic plasticity (Burnstock et al.2011, Costa et al.2015, Akinyemi et al.2017). The decrease in ADA activity observed in the shaddock peel extract-treated group as shown in Figure 5 suggests possible mechanisms governing shaddock peel extract or donepezil action on cognitive function. This inhibitory effect on brain ADA activity would have a direct or indirect influence on the prevention of adenosine degradation in the CNS.
A case report of peritoneal tuberculosis diagnosed by laparoscopy in a low prevalence setting
Published in Acta Chirurgica Belgica, 2021
Jan Van Slambrouck, Johan Vlasselaers, Bart Devos
Paracentesis is the least invasive procedure that can confirm the diagnosis of peritoneal TB. Results of biochemical analysis and cytology of peritoneal fluid can increase the clinicians’ index of suspicion. A low serum-ascites albumin gradient (SAAG) of <1.1 g/dL and presence of lymphocytes in ascitic fluid are compatible with peritoneal TB [3]. Measurement of ascitic adenosine deaminase (ADA) activity is a recently established test with a high diagnostic yield that is especially helpful as a screening test for patients with ascites in high prevalence countries. However, it is not widely used in the Western European setting. Biochemical and cytological findings after ascitic fluid analysis only suggest the diagnosis of peritoneal TB. An ascitic fluid smear test for Ziehl–Neelsen acid-fast bacilli staining is very specific but sensitivity is low [11]. Conventional mycobacterial cultures take 4–6 weeks and isolation of bacilli is rare [5]. Molecular PCR assays are a new alternative that can reveal presence of M. tuberculosis complex in peritoneal fluid within a short amount of time [10,11]. As PCR techniques evolve, diagnostic yield and availability increases [11].