Co-infection of COVID-19 and Tuberculosis in a Tertiary Care Hospital

Introduction: The burden of Tuberculosis (TB) has managed to remain an age old menace to our society, especially India. The potential impact of Corona Virus Disease-19 (COVID-19) on TB patients continues to be worrisome due to the disruption of the national program and its services. Aim: To compare the TB infection in COVID-19 vs non-COVID-19 patients. Materials and Methods: The study was undertaken at Department of Microbiology, ABVIMS, Dr. RML Hospital Delhi, India. The data was collected, retrospectively from 15thSeptember 2020 to 15th January 2021 from admitted 1094 non-COVID-19 and 150 COVID-19 patients, >18 years of age, either sex. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was done to diagnose COVID-19 and GeneXpert was used to detect Mycobacterium tuberculosis. The data entry was done in the Microsoft Excel spreadsheet and the final analysis was done with the use of Statistical Package for Social Sciences(SPSS) software version 21.0. Two by two contingency table was used for calculating the Odd’s ratio. Results: During the study period, 1094 samples were received from non-COVID-19 ward and 150 from COVID-19 ward. Out of 150 COVID-19 positive patients, 30 (20%) were also positive for Mycobacterium tuberculosis Complex (MTBC) and 120 (80%) were negative for MTBC. Out of 1094 COVID-19 negative patients, 98 (8.96%) were positive for MTBC and 996 (91.04%) were negative for MTBC. The Odd’s ratio/Risk Ratio (RR) of TB infection in COVID-19 infected patients was 3.08 {Confidence Interval (CI) 95%}. The mortality was 10% in the COVID-19 positive group. Conclusion: It was observed that the chances of contracting TBare thrice in COVID-19 patients and thus TB diagnosis should be equally emphasised and further strengthened in this ongoing pandemic.

Performance of Chip Based Real Time RT- PCR (TrueNat) and Conventional Real Time RT-PCR for Detection of SARS-CoV-2

Introduction: Coronavirus Disease-2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is ravaging the globe due to its rapid spread. Since providing fast results is of critical importance in a time of shortage of medical personnel and beds in isolation wards and to ensure timely treatment for patients, developing high quality rapid Point of Care (POC) diagnostics is essential. Aim: To compare the diagnostic performance of chip based real time Reverse Trancriptase Polymerase Chain Reaction (RT- PCR) (TrueNat) which has a shorter turnaround time compared to conventional real time RT-PCR in samples of suspected COVID-19 patients. Materials and Methods: The present cross-sectional observational study was carried out in a tertiary care hospital in New Delhi, India. Five hundred randomly selected Oropharyngeal (OP) swabs samples received from May-July 2020, were included in the study to compare the diagnostic performance of chip based real time RT- PCR (TrueNat) with conventional real time RT-PCR for diagnosis of SARS-CoV-2 infection. All statistical analysis was performed using STATA version 16.1 software (College station, Texas, USA). Results: The sensitivity of TrueNat test was 100% while the specificity was found to be 99.12% at 95% confidence intervals. The positive predictive value was 91.84% and the negative predictive value was 100%. Conclusion: The short turnaround time, good sensitivity and specificity makes TrueNat a reliable and affordable option to provide rapid results in cases requiring urgent interventions and to augment SARS-CoV-2 testing capacity at peripheral settings where sample load is less.

Diagnosis of pulmonary tuberculosis from gastric aspirate samples in nonexpectorating pediatric patients in a tertiary care hospital

Objectives

The aim of this study was to assess the utility of Xpert assay, Ziehl-Neelsen (ZN) staining, and Mycobacteria Growth Indicator Tube (MGIT™) culture for diagnosis of pediatric pulmonary tuberculosis from gastric aspirate (GA) samples and to compare Xpert assay and ZN staining with MGIT rapid liquid culture.

Materials and Methods

GA samples from 210 nonexpectorating children, aged between 6 months to 12 years, presenting to the pediatric out-patient department (OPD) with clinical suspicion of tuberculosis (TB) were collected. The samples were tested by GeneXpert, ZN staining, and MGIT liquid culture.

Results

GeneXpert is a more sensitive method for rapid and early diagnosis of pediatric TB when compared with microscopy.

Differential utilization and localization of ErbB receptor tyrosine kinases in skin compared to normal and malignant keratinocytes

Induction of heparin-binding epidermal growth factor-like growth factor (HB-EGF) mRNA in mouse skin organ culture was blocked by two pan-ErbB receptor tyrosine kinase (RTK) inhibitors but not by genetic ablation of ErbB1, suggesting involvement of multiple ErbB species in skin physiology. Human skin, cultured normal keratinocytes, and A431 skin carcinoma cells expressed ErbB1, ErbB2, and ErbB3, but not ErbB4. Skin and A431 cells expressed more ErbB3 than did keratinocytes. Despite strong expression of ErbB2 and ErbB3, heregulin was inactive in stimulating tyrosine phosphorylation in A431 cells. In contrast, it was highly active in MDA-MB-453 breast carcinoma cells. ErbB2 displayed punctate cytoplasmic staining in A431 and keratinocytes, compared to strong cell surface staining in MDA-MB-453. In skin, ErbB2 was cytoplasmic in basal keratinocytes, assuming a cell surface pattern in the upper suprabasal layers. In contrast, ErbB1 retained a cell surface distribution in all epidermal layers. Keratinocyte proliferation in culture was found to be ErbB1-RTK-dependent, using a selective inhibitor. These results suggest that in skin keratinocytes, ErbB2 transduces ligand-dependent differentiation signals, whereas ErbB1 transduces ligand-dependent proliferation/survival signals. Intracellular sequestration of ErbB2 may contribute to the malignant phenotype of A431 cells, by allowing them to respond to ErbB1-dependent growth/survival signals, while evading ErbB2-dependent differentiation signals.

Bob1, a Gim5/MM-1/Pfd5 homolog, interacts with the MAP kinase kinase Byr1 to regulate sexual differentiation in the fission yeast, Schizosaccharomyces pombe

The MAPKK Byr1 is an essential component of a Ras-dependent MAPK module required for sexual differentiation in the fission yeast, Schizosaccharomyces pombe. Here we describe the genetic and molecular characterization of a highly conserved protein, Bob1, which was identified from a two-hybrid screen for Byr1-interacting proteins. Byrl and Bobl proteins coprecipitate from S. pombe cell lysates, and both proteins localize to the tips and septa of S. pombe cells. S. pombe bob1 null (bob1delta) mutants lack obvious growth defects but exhibit a significant mating deficiency, which can be suppressed by overexpression of Byrl. Overexpression of Bob1 also leads to inhibition of mating in S. pombe, and this defect is likewise suppressed by Byrl overexpression. Bob1 is highly homologous in structure to the mammalian MM-1/Pfd5 and budding yeast Gim5/Pfd5-Sc proteins, which have been implicated as regulators of actin and tubulins. Similar to budding yeast gim5/pfd5-Sc mutants, S. pombe bob1delta cells have cytoskeletal defects, as judged by hypersensitivity to cytoskeletal disrupting drugs. byr1delta mutants do not share this characteristic with bob1delta mutants, and byr1delta bob1delta mutants are not significantly more sensitive to cytoskeletal disrupting drugs than cells carrying only the bob1delta mutation. Taken together, our results suggest that Bob1 has Byr1-related function(s) required for proper mating response of S. pombe cells and Byrl-independent function(s) required for normal cytoskeletal control. We show that the human MM-1/Pfd5 protein can substitute for its counterpart in fission yeast, providing evidence that the functions of Bob1-related proteins have been highly conserved through evolution. Our results lead us to propose that Bob1-related proteins may play diverse roles in eukaryotic organisms.

IGFBP-3 mediates TGF beta 1 proliferative response in colon cancer cells

Many human tumor cells are resistant to growth inhibition by TGF beta 1. Resistance may be caused by mutations in TGFbeta receptors or in other components of the TGF beta signal transduction systems, or by knockout of the retinoblastoma (Rb) gene, which in fibroblasts converts cellular response to TGF beta 1 from growth inhibition to growth stimulation. Our earlier studies showed such a switch in response to TGF beta 1 occurred in 45% of colon cancers but without deletion of Rb. We now show that insulin-like growth factor binding protein 3 (IGFBP-3) mediates the TGF beta 1-induced proliferation of 3 metastatic or highly aggressive colon carcinoma cell lines. TGF beta 1 increases IGFBP-3 abundance while phosphorothiolated antisense oligonucleotides to IGFBP-3 block the growth-promoting effect of TGF beta 1 in each of 3 lines.IGFBP-3 induces carcinoma cell growth in a dose-dependent and time-dependent manner in vitro. IGFBP-3 may confer a selective growth advantage on tumor cells in vivo because levels of mature IGFBP-3 were elevated at least 2-fold in 7 of 10 resected colon cancers compared with adjacent normal tissue.

Negative regulation of mitosis in fission yeast by the shk1 interacting protein skb1 and its human homolog, Skb1Hs

We previously provided evidence that the protein encoded by the highly conserved skb1 gene is a putative regulator of Shk1, a p21(Cdc42/Rac)-activated kinase (PAK) homolog in the fission yeast Schizosaccharomyces pombe. skb1 null mutants are viable and competent for mating but less elongate than wild-type S. pombe cells, whereas cells that overexpress skb1 are hyperelongated. These phenotypes suggest a possible role for Skb1 as a mitotic inhibitor. Here we show genetic interactions of both skb1 and shk1 with genes encoding key mitotic regulators in S. pombe. Our results indicate that Skb1 negatively regulates mitosis by a mechanism that is independent of the Cdc2-activating phosphatase Cdc25 but that is at least partially dependent on Shk1 and the Cdc2 inhibitory kinase Wee1. We provide biochemical evidence for association of Skb1 and Shk1 with Cdc2 in S. pombe, suggesting that Skb1 and Shk1 inhibit mitosis through interaction with the Cdc2 complex, rather than by an indirect mechanism. These results provide evidence of a previously undescribed role for PAK-related protein kinases as mitotic inhibitors. We also describe the cloning of a human homolog of skb1, SKB1Hs, and show that it can functionally replace skb1 in S. pombe. Thus, the molecular functions of Skb1-related proteins have likely been substantially conserved through evolution.

Cloning and characterization of shk2, a gene encoding a novel p21-activated protein kinase from fission yeast

We describe the characterization of a novel gene, shk2, encoding a second p21(cdc42/rac)-activated protein kinase (PAK) homolog in fission yeast. Like other known PAKs, Shk2 binds to Cdc42 in vivo and in vitro. While overexpression of either shk2 or cdc42 alone does not impair growth of wild type fission yeast cells, cooverexpression of the two genes is toxic and leads to highly aberrant cell morphology, providing evidence for functional interaction between Cdc42 and Shk2 proteins in vivo. Fission yeast shk2 null mutants are viable and exhibit no obvious phenotypic defects. Overexpression of shk2 restores viability and normal morphology but not full mating competence to fission yeast cells carrying a shk1 null mutation. Additional genetic data suggest that Shk2, like Cdc42 and Shk1, participates in Ras-dependent morphological control and mating response pathways in fission yeast. We also show that overexpression of byr2, a gene encoding a Ste11/MAPK kinase kinase homolog, suppresses the mating defect of cells partially defective for Shk1 function, providing evidence of a link between PAKs and mitogen-activated protein kinase signaling in fission yeast. Taken together, our results suggest that Shk2 is partially overlapping in function with Shk1, with Shk1 being the dominant protein in function.

Potentiation of cyclic adenosine monophosphate production by thrombin in the human erythroleukemia cell line, HEL

The human erythroleukemia cell line (HEL) has been used as a model system for studying signal transduction processes as they might relate to platelet/megakaryocyte function. We were interested in examining the role of thrombin in the regulation of adenylyl cyclase in this cell line. As opposed to its predominantly inhibitory effects on cyclic AMP production in platelets or in membranes from HEL cells, our initial experiments in intact HEL cells revealed that thrombin markedly potentiated the cyclic AMP response to prostaglandin E1 (2.9 +/- 0.2-fold), prostacyclin (1.9 +/- 0.2-fold) and carbacyclin (2.5 +/- 0.5-fold), measured either by radioimmunoassay or by the [3H]adenine preloading procedure. Thrombin, although ineffective alone, also potentiated cyclic AMP production stimulated by vasoactive intestinal peptide (1.6 +/- 0.2-fold), cholera toxin (3.0 +/- 0.6-fold) and AIF4- (2.3 +/- 0.6-fold), but not by forskolin (0.9 +/- 0.1-fold). The thrombin effect 1) produced an increase in the efficacy of the prostaglandins with no change in potency; 2) was long-lived; 3) required the proteolytic activity of thrombin; 4) was insensitive to pertussis toxin; and 5) was at least partially mimicked by trypsin, extracellular ATP and UTP, platelet activating factor and activators of protein kinase C. Down-regulation of protein kinase C or pre-exposure to the protein kinase inhibitor staurosporine blocked the potentiating effect. Together, these results suggest that in HEL cells, the mechanism of thrombin potentiation of cyclic AMP production may involve alterations in the interaction between stimulatory guanine nucleotide binding protein and the catalytic subunit of adenylyl cyclase, possibly involving protein kinase C-mediated phosphorylation.