To report on 5-year multimodal imaging of ocular findings in a patient with thiamine-responsive megaloblastic anemia.
Observational case report.
A 20-year-old-man with a history of ...thiamine-responsive megaloblastic anemia demonstrated a symmetric bull's eye maculopathy. Spectral domain optical coherence tomography revealed disruption of the parafoveal ellipsoid zone, fundus autofluorescence demonstrated foveal hypoautofluorescence, and full-field electroretinogram testing revealed a decreased photopic and scotopic response consistent with cone-rod dystrophy. His best-corrected visual acuity remained stable over 5 years at 20/50 in the right eye and 20/40 in the left eye, and visual field testing remained stable over time.
Ocular manifestations in thiamine-responsive megaloblastic anemia are uncommon and variable. In this case, multimodal imaging and electroretinogram findings are consistent with cone-rod degeneration. The patient is taking daily thiamine supplementation, and visual acuity, funduscopic examination, spectral domain optical coherence tomography, and autofluorescence remained stable over a 5-year period.
Pus10, a recently identified pseudouridine (Psi) synthase, does not belong to any of the five commonly identified families of Psi synthases. Pyrococcus furiosus Pus10 has been shown to produce Psi55 ...in tRNAs. However, in vitro studies have identified another mechanism for tRNA Psi55 production in Archaea, which uses Cbf5 and other core proteins of the H/ACA ribonucleoprotein complex, in a guide RNA-independent manner. Pus10 homologs have been observed in nearly all sequenced archaeal genomes and in some higher eukaryotes, but not in yeast and bacteria. This coincides with the presence of Psi54 in the tRNAs of Archaea and higher eukaryotes and its absence in yeast and bacteria. No tRNA Psi54 synthase has been reported so far. Here, using recombinant Methanocaldococcus jannaschii and P. furiosus Pus10, we show that these proteins can function as synthase for both tRNA Psi54 and Psi55. The two modifications seem to occur independently. Salt concentration dependent variations in these activities of both proteins are observed. The Psi54 synthase activity of M. jannaschii protein is robust, while the same activity of P. furiosus protein is weak. Probable reasons for these differences are discussed. Furthermore, unlike bacterial TruB and yeast Pus4, archaeal Pus10 does not require a U54 x A58 reverse Hoogstein base pair and pyrimidine at position 56 to convert tRNA U55 to Psi55. The homology of eukaryal Pus10 with archaeal Pus10 suggests that the former may also have a tRNA Psi54 synthase activity.
RFID is a system that uses the radio waves to scrutinize and capture data pertained to a tag for an object attached to it. In spite of RFID's wide application in industries, it poses a severe ...security issue. There is high susceptibility that RFID might be attacked with future attacks to invade the privacy and data in the system. To protect the RFID system against such attacks, the Pad-generation (Pad-Gen) function is used. This paper presents a mutual authentication scheme Tag Reader Mutual Authentication (TRMA) that is implemented using two approaches, the XOR operation and the MOD operation by modifying the Pad-Gen function. The proposed framework is executed on low-cost Artix7 FPGA XC7A100T-3CSG324, and its hardware verification is done on chip scope pro tool.
Thiamin is essential for the normal function of the endocrine pancreas, but very little is known about uptake mechanism(s) and regulation by beta cells. We addressed these issues using mouse-derived ...pancreatic beta-TC-6 cells, and freshly isolated primary mouse and human pancreatic islets. Results showed that thiamin uptake by beta-TC-6 cells involves a pH (but not Na+)-dependent carrier-mediated process that is saturable at both the nanomolar (apparent K(m) = 37.17 +/- 9.9 nM) and micromolar (apparent K(m) = 3.26 +/- 0.86 microM) ranges, cis-inhibited by thiamin structural analogs, and trans-stimulated by unlabeled thiamin. Involvement of carrier-mediated process was also confirmed in primary mouse and human pancreatic islets. Both THTR-1 and THTR-2 were found to be expressed in these mouse and human pancreatic preparations. Maintaining beta-TC-6 cells in the presence of a high level of thiamin led to a significant (P < 0.01) decrease in thiamin uptake, which was associated with a significant downregulation in level of expression of THTR-1 and THTR-2 at the protein and mRNA levels and a decrease in transcriptional (promoter) activity. Modulators of intracellular Ca2+/calmodulin- and protein-tyrosine kinase-mediated pathways also altered thiamin uptake. Finally, confocal imaging of live beta-TC-6 cells showed that clinical mutants of THTR-1 have mixed expression phenotypes and all led to impairment in thiamin uptake. These studies demonstrate for the first time that thiamin uptake by the endocrine pancreas is carrier mediated and is adaptively regulated by the prevailing vitamin level via transcriptional mechanisms. Furthermore, clinical mutants of THTR-1 impair thiamin uptake via different mechanisms.
Thiamine-responsive megaloblastic anemia (TRMA) is a rare disorder typically characterized by megaloblastic anemia, non-type I diabetes and sensorineural deafness. It is caused by various mutations ...in the
SLC19A2
gene that impair the encoded thiamine transporter. So far, only 70 affected individuals mainly from consanguineous families of Middle and Far Eastern origin with a wide spectrum of signs and symptoms, variable onset of disease, and primarily homozygote mutations in
SLC19A2
have been reported. We present the first genuine central European descendent with combined heterozygote mutations in
SLC19A2
, an Austrian boy suffering from pancytopenia and non-type I diabetes. Both manifestations resolved completely under continuous oral thiamine supplementation. Our observation underlines that despite its rarity, TRMA must be considered as an important differential diagnosis in native central European patients with suggestive signs and symptoms. An early molecular genetic verification of the diagnosis provides a sound basis for a successful and simple treatment that helps to prevent severe sequelae.
Thiamine-responsive megaloblastic anaemia (TRMA) is a rare syndrome presenting with early onset non-autoimmune diabetes mellitus, megaloblastic anaemia and sensorineural deafness. We report a ...16-month-old male, a youngest case of genetically confirmed TRMA syndrome in Indian phenotype, born to consanguineous parents. We found a homozygous pathogenic variant in exon 2 of the SLC19A2 gene, c.314G>A (p.Gly105Glu). The anaemia showed a good response to daily thiamine doses and was able to avoid unwanted blood transfusion. There was no benefit with regard to insulin requirement. Early detection of hearing impairment and referral to audiological treatment was possible. The report indicates that TRMA should be considered as a differential diagnosis for patients presenting with suggestive clinical symptoms which would have tremendous impact on patient management if identified early.
Type 2 diabetes mellitus is caused by a combination of insulin resistance and β cell failure. The polygenic nature of type 2 diabetes has made it difficult to study. Although many candidate genes for ...this condition have been suggested, in most cases association studies have been equivocal. Monogenic forms of diabetes have now been studied extensively, and the genetic basis of many of these syndromes has been elucidated, leading to greater understanding of the functions of the genes involved. Common variations in the genes causing monogenic disorders have been associated with susceptibility to type 2 diabetes in several populations and explain some of the linkage seen in genome-wide scans. Monogenic disorders are also helpful in understanding both normal and disordered glucose and insulin metabolism. Three main areas of defect contribute to diabetes: defects in insulin signalling leading to insulin resistance; defects of insulin secretion leading to hypoinsulinaemia; and apoptosis leading to decreased β cell mass. These three pathological pathways are reviewed, focusing on rare genetic syndromes which have diabetes as a prominent feature. Apoptosis seems to be a final common pathway in both type 1 and type 2 diabetes. Study of rare forms of diabetes may help ion determining new therapeutic targets to preserve or increase β cell mass and function.
The truB gene of Escherichia coli encodes the pseudouridine-55 (psi55) synthase and is responsible for modifying all tRNA molecules in the cell at the U55 position. A truB null mutant grew normally ...on all growth media tested, but exhibited a competitive disadvantage in extended co-culture with its wild-type progenitor. The mutant phenotype could be complemented by both the cloned truB gene and by a D48C, catalytically inactive allele of truB. The truB mutant also exhibited a defect in survival of rapid transfer from 37 to 50 degrees C. This mutant phenotype could be complemented by the cloned truB gene but not by a D48C, catalytically inactive allele of truB. The temperature sensitivity of truB mutants could be enhanced by combination with a mutation in the trmA gene, encoding an m(5)U-methyltransferase, modifying the universal U54 tRNA nucleoside, but not by mutations in trmH, encoding the enzyme catalysing the formation of Gm18. The truB mutant proteome contained altered levels of intermediates involved in biogenesis of the outer-membrane proteins OmpA and OmpX. The truB mutation also reduced the basal expression from two sigma(E) promoters, degP and rpoHP3. Three novel aspects to the phenotype of truB mutants were identified. Importantly the data support the hypothesis that TruB-effected psi55 modification of tRNA is not essential, but contributes to thermal stress tolerance in E. coli, possibly by optimizing the stability of the tRNA population at high temperatures.
To report ophthalmologic fundus autofluorescence and spectral domain optical coherence tomography findings in a patient with thiamine responsive megaloblastic anemia (TRMA).
A 13-year-old girl with ...genetically proven TRMA was ophthalmologically (visual acuity, funduscopy, perimetry, electroretinogram) followed up over >5 years. Fundus imaging also included autofluorescence and spectral domain optical coherence tomography.
During a 5-year follow-up, visual acuity and visual field decreased, despite a special TRMA diet. Funduscopy revealed bull's eye appearance, whereas fundus autofluorescence showed central and peripheral hyperfluorescence and perifoveal hypofluorescence. Spectral domain optical coherence tomography revealed affected inner segment ellipsoid band and irregularities in the retinal pigment epithelium and choroidea.
Autofluorescence and spectral domain optical coherence tomography findings in a patient with TRMA show retinitis pigmentosa-like retina, retinal pigment epithelium, and choroid alterations. These findings might progress even under special TRMA diet, indispensable to life. Ophthalmologist should consider TRMA in patients with deafness and ophthalmologic disorders.
In bacteria, trans-translation rescues stalled ribosomes by the combined action of tmRNA (transfer-mRNA) and its associated protein SmpB. The tmRNA 5′ and 3′ ends fold into a tRNA-like domain (TLD), ...which shares structural and functional similarities with tRNAs. As in tRNAs, the UUC sequence of the T-arm of the TLD is post-transcriptionally modified to m
5
UψC. In tRNAs of gram-negative bacteria, formation of m
5
U is catalyzed by the SAM-dependent methyltransferase TrmA, while formation of m
5
U at two different positions in rRNA is catalyzed by distinct site-specific methyltransferases RlmC and RlmD. Here, we show that m
5
U formation in tmRNAs is exclusively due to TrmA and should be considered as a dual-specific enzyme. The evidence comes from the lack of m
5
U in purified tmRNA or TLD variants recovered from an Escherichia coli mutant strain deleted of the trmA gene. Detection of m
5
U in RNA was performed by NMR analysis.
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