Phylogenetic analysis and antimicrobial activities of Streptomyces isolates from mangrove sediment

The phylogeny of members of Streptomyces bacteria isolated from mangrove sediments in the Manakudi estuary near the Arabian Sea, India, was analyzed in the present study. Among the 35 different isolates, five organisms, JS-9, JS-11, JS-12, JS-13 and JS-20, exhibited potent antimicrobial effects against methicillin-resistant Staphylococcus aureus (clinical isolate) and methicillin-susceptible S. aureus MTCC 3160 and Salmonella typhi MTCC 733; all other isolates displayed intermediate antimicrobial effects. RFLP analysis of HaeIII and BstUI double-digested 16S rRNA gene fragments of the isolates were distinguished into 20 distinct RFLP types, with the genetic similarity coefficient varying from 0.57 to 0.97. On average, 17 RFLP markers were observed from approximately 50 to 350 bp size and all the RFLP types showed significant genetic polymorphism by clustering into three major clusters. Phylogenetic analysis showed that the 20-member Streptomyces isolates were divided into three major clusters and they shared 97.2-99.8% sequence identity to the 16S rRNA gene sequences of the Streptomyces taxons of marine origin. The distribution of the isolates revealed that the distinct Streptomyces groups were clustered in the phylogenetic tree and there was a good correlation between the diversity of the antimicrobial phenotype and that of the 16S rRNA gene.     

Proteasome function is required for platelet production

The proteasome inhibiter bortezomib has been successfully used to treat patients with relapsed multiple myeloma; however, many of these patients become thrombocytopenic, and it is not clear how the proteasome influences platelet production. Here we determined that pharmacologic inhibition of proteasome activity blocks proplatelet formation in human and mouse megakaryocytes. We also found that megakaryocytes isolated from mice deficient for PSMC1, an essential subunit of the 26S proteasome, fail to produce proplatelets. Consistent with decreased proplatelet formation, mice lacking PSMC1 in platelets (Psmc1^fl/fl Pf4-Cre mice) exhibited severe thrombocytopenia and died shortly after birth. The failure to produce proplatelets in proteasome-inhibited megakaryocytes was due to upregulation and hyperactivation of the small GTPase, RhoA, rather than NF-κB, as has been previously suggested. Inhibition of RhoA or its downstream target, Rho-associated protein kinase (ROCK), restored megakaryocyte proplatelet formation in the setting of proteasome inhibition in vitro. Similarly, fasudil, a ROCK inhibitor used clinically to treat cerebral vasospasm, restored platelet counts in adult mice that were made thrombocytopenic by tamoxifen-induced suppression of proteasome activity in megakaryocytes and platelets (Psmc1^fl/fl Pdgf-Cre-ER mice). These results indicate that proteasome function is critical for thrombopoiesis, and suggest inhibition of RhoA signaling as a potential strategy to treat thrombocytopenia in bortezomib-treated multiple myeloma patients.     

Inherited paediatric neurometabolic disorders,can brain magnetic resonance imaging predict?

Objectives:To evaluate diagnostic capability of brain magnetic resonance imaging (MRI) in detection of inherited neurometabolic disorders.Methods:This retrospective observational study was performed in Radiology Department at our Hospital in Dhahran, from January 2013 to January 2020. We evaluated brain MRIs of children (under 5) who were referred to pediatric neurology for clinical suspicion of neuro-developmental delay and metabolic disease. Known perinatal ischemia and birth trauma cases were excluded. Imaging criteria included: (i) bilateral symmetric white matter signal abnormality, (ii) diffusion restriction affecting bilateral deep grey nuclei with or without brainstem involvement, (iii) brain atrophy or edema with abnormal white matter signal, (iv) characteristic MR spectroscopic finding. Presence of any one of these findings was considered positive for neurometabolic disease. Two neuroradiologists interpreted MRIs with substantial interobserver agreement. Diagnoses were confirmed on biochemical/ metabolic screening and genetic testing. A 2 × 2 contingency table was used for results. Chi square test was used to determine association.Results:Out of 133 cases, 72 (49 males, 90% AR) were found to have neurometabolic disorders. Sensitivity, specificity, positive and negative predictive values were calculated as 81.94% (CI, 71.11-90.02), 67.21% (CI, 54.00-78.69), 74.68% (CI, 66.96-81.11) and 75.93% (CI, 65.16-84.17) respectively. Findings were found significant (p-value=0.0001).Conclusion:Brain MRI can help to predict inherited neurometabolic disorders considering certain findings.

Metabolic diseases can be either inherited (inborn errors of metabolism) or acquired. Inborn errors of metabolism (IEMs) that primarily affect the central nervous system are referred to as neurometabolic diseases, and usually occur in neonates and infants.1 These diseases involve genetic defects that result in certain enzyme deficiency leading to deficiency of essential metabolite or toxic accumulation of others with specific biochemical and molecular abnormalities. Clinical presentations may be confusing and potentially lead to delay in diagnosis and treatment.2 Overall incidence of this group of disorders may vary from region to region, being much higher in communities with consanguineous marriages, ranging from 1.2 to 2 per 100,000 live births.3 Most exhibit autosomal recessive (AR) mode of inheritance. Neurometabolic disorders can be classified by various methods based on clinical and biochemical characteristics, area of brain involvement, or cellular organelle.4 Imaging based classification includes leukodystrophy (primary involvement of white matter due to genetic abnormality), leukoencephalopathy (secondary involvement of white matter either due to genetic or acquired systemic disorder), poliodystrophy (predominant involvement of grey matter), and pandydystrophy (mixed involvement of both white and grey matter).5 Central nervous system white matter is usually affected,6 and can result from various pathologic process like delayed myelination (myelin maturation delayed for expected age), hypomyelination (scarcity of myelin or arrest in myelination process), dysmyelination (deposition of abnormally composed fragile myelin), demyelination (secondary loss of myelin that may have been previously normal) and myelinopathy (vacuolating due to deranged brain iron and water hemostasis).Magnetic resonance imaging is the modality of choice for evaluation of neurometabolic disorders.7 Analyzing pattern recognition in MR imaging and clinical clues help to narrow the differential, tailor subsequent laboratory (targeted metabolomics) or genetic investigations (either requiring single gene testing or broad-spectrum genetic testing i.e., whole exome sequencing/ WES).4 The MRI can be helpful in diagnostic workup of various diseases and may be decisive for early management even before arrival of costly and time-consuming biochemical or genetic testing results.8 We therefore sought to highlight ability of MRI in predicting diagnoses of inherited neurometabolic disorders in neonates and young children considering certain MRI findings.     

Hemophagocytic lymphohistiocytosis (HLH) presenting on the 3rd day of life

Hemophagocytic lymphohistiocytosis (HLH) embraces the frequently indistinguishable conditions, namely familial hemophagocytic lymphohistiocytosis (FHLH), sporadic hemophagocytic lymphohistiocytosis (SHLH) and virus associated hemophagocytic syndrome (VAHS). The disease is very rare and invariably lethal. Evidence suggests that the disease may be due to an inherited defect in immunoregulation that predisposes to an uncontrolled proliferation of activated histiocytes in response to a stimulus such as viral infection. We report here a 3-day-old neonate with confirmed HLH who had a stormy course and a fatal outcome to the disease process, in spite of early chemotherapy. To our knowledge, we believe this is the youngest reported case of HLH from Middle East. No familial or infective cause could be attributed.     

Growth hormone therapy in patients with dilated cardiomyopathy: preliminary observations of a pilot study.

The effects of growth hormone in six patients with dilated cardiomyopathy were evaluated in this study. The patients were studied at baseline, after six months of therapy and at six months after stopping the treatment. They were given two units of growth hormone on alternate days by subcutaneous injection. There was marked improvement in the symptomatic class with treatment (NYHA class 3.4 +/- 0.5 vs 2 +/- 0; p = 0.04). There was also significant increase in the inteventricular septal wall thickness (6.4 +/- 1.5 mm vs 10.4 +/- 0.5 mm; p = 0.04). Left ventricular posterior wall thickness also increased significantly (7.2 +/- 1.3 mm vs 10.2 +/- 0.8 mm; p = 0.04). These changes were partially reversed by the end of six months of treatment but the symptomatic status of these patients was better than before. The administration of growth hormone for six months in patients with dilated cardiomyopathy results in significant improvement in the symptomatic class, which could be considered as an additional line of management in patients with heart failure in dilated cardiomyopathy.     

LDL attenuates VEGF-induced angiogenesis via mechanisms involving VEGFR2 internalization and degradation following endosome-trans-Golgi network trafficking

Considerable efforts have been made to amplify angiogenesis under conditions of hypoxia and ischemia by vascular endothelial growth factor (VEGF) delivery, so far with limited success. Ischemic vascular diseases are often associated with hypercholesterolemia. To elucidate whether the exposure to blood lipids influences VEGF responses of microvessels, we characterized effects of low density lipoprotein (LDL) exposure on the proliferation, migration and tube formation of human umbilical vein endothelial cells. By examining the expression, phosphorylation and downstream signals of VEGF’s receptor VEGFR2, we characterized mechanisms controlling angiogenic responses following LDL exposure. LDL attenuated endothelial proliferation, migration and tube formation in a dose-dependent way. Reduced abundance of VEGFR2 and VEGFR1 were noticed in LDL-exposed endothelial cells. In subcellular localization studies that we combined with pharmacological experiments, we showed that the loss of VEGFR2 resulted from its internalization and degradation, the latter of which required syntaxin-16-dependent endosome-trans-Golgi network trafficking. As a consequence, VEGFR2 phosphorylation and downstream signals -specifically Akt and ERK1/2 phosphorylation- were attenuated in response to VEGF treatment. VEGF only partly reversed the effects of LDL on angiogenesis under conditions of normoxia and hypoxia. Our results suggest that angiogenic responses to VEGF are compromised in hypercholesterolemia as a consequence of endosomal VEGFR2 degradation.