Single breath count test and its applications in clinical practice: a systematic review

Background

Single breath count test (SBCT) may be a reproducible, rapid, easy to perform and easy to interpret substitute to spirometry especially in low resource settings for certain conditions. Its interest has been rekindled with the recent COVID-19 pandemic and it can be done as a part of tele-medicine as well.

Objectives

The objective of this review was to summarize the evidence of SBCT in clinical practice.

Methods

The authors searched EMBASE, PubMed and Google Scholar for all the relevant articles as per exclusion and inclusion criteria. Two authors independently screened all the studies. Newcastle Ottawa Scale was used to assess the quality of the studies. The systematic review was carried following the PRISMA guidelines.

Results

After the rigorous process of screening, a total of 13 articles qualified for the systematic review. SBCT greater than 25 had sensitivity of greater than 80% in diagnosing myasthenia gravis exacerbation and SBCT less than or equal to 5 predicted the need for mechanical ventilation in Guillain-Barre syndrome (GBS) patients with 95.2% specificity. Also, Single breath count correlated significantly with forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) in children with pulmonary pathology and in patients with COVID-19 it was used to rule out the need for noninvasive respiratory support.

Conclusion

SBCT will undoubtedly be an asset in low resource settings and in tele-medicine to assess the prognosis and guide management of different respiratory and neuromuscular diseases.

Assessing the comparative efficacy of plasmapheresis and Intravenous immunoglobulin in myasthenia gravis treatment: A systematic review and meta-analysis

BACKGROUND

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterized by muscle weakness, posing significant challenges to patients' daily lives. Intravenous immunoglobulin (IVIG) and plasmapheresis are two prominent immunomodulatory therapies used in MG management, but the choice between them remains a clinical dilemma. This systematic review and meta-analysis aim to evaluate the comparative efficacy of IVIG versus plasmapheresis in MG management.

METHODS

We adhered to PRISMA guidelines and prospectively registered the review protocol in PROSPERO. Systematic search across electronic databases identified 14 studies meeting inclusion criteria. Data from these studies were extracted, and assessed risk of bias. Primary outcomes included clinical efficacy, while secondary outcomes encompassed hospitalization, ventilation, antibody titers, and treatment-related complications. Statistical analysis was conducted using R software.

RESULTS

The pooled results indicated that patients receiving plasmapheresis had higher odds of any improvement in MG symptoms compared to IVIG. However, change in severity scores did not significantly differ between the two treatments. Hospitalization durations were similar, but IVIG-treated patients tended to have shorter stays. Antibody titers, particularly anti-MUSK antibodies, favored plasmapheresis treatment. Complication rates were comparable between two groups. However, severe complications were more common in plasmapheresis.

CONCLUSION

This comprehensive analysis suggests that plasmapheresis may offer superior short-term symptom improvement in MG compared to IVIG, while IVIG may lead to shorter hospital stays and lower complication rates. The choice between these treatments should be tailored to individual patient needs and disease characteristics. Further research is needed to explore long-term outcomes and mortality rates in MG management.

Diagnostic accuracy of glycogen phosphorylase BB for myocardial infarction: A systematic review and meta-analysis

PURPOSE

We tried to investigate the diagnostic accuracy of glycogen phosphorylase BB as a cardiac marker for myocardial infarction.

METHODS

We searched through different electronic databases (PubMed, Google-scholar, Embase, and Cochrane Library) to locate relevant articles. Studies, with sufficient data to reconstruct a 2 × 2 contingency table, met our inclusion criteria were included. Three reviewers independently screened the articles. Discrepancies were resolved by other reviewers. Unpublished data were requested from the authors of the study via email. Subsequently, data extraction was done using a standardized form and quality assessment of studies using the QUADAS-2 tool. Meta-analysis was done using a bivariate model using R software.

RESULTS

Fourteen studies were selected for the final evaluation, which yielded the summary points: pooled sensitivity 87.77% (77.52%-93.72%, I2  = 86%), pooled specificity 88.45% (75.59%-94.99%, I2  = 88%), pooled DOR 49.37(14.53-167.72, I2  = 89%), and AUC of SROC was 0.923. The lambda value of the HSROC curve was 3.670. The Fagan plot showed that GPBB increases the pretest probability of myocardial infarction from 46% to 81% when positive, and it lowers the same probability to 12% when negative.

CONCLUSION

With these results, we can conclude that GPBB has modest accuracy in screening myocardial infarction, but the limitations of the study warrant further high-quality studies to confirm its usefulness in predicting myocardial infarction (MI).

Adrenal Leiomyoma: A case report

Introduction and importance

Adrenal Leiomyomas are infrequent tumors with only a few cases reported to date. They are difficult to differentiate from malignant adrenal tumors due to non-specific findings on clinical examination and imaging studies.

Case presentation

We discuss the case of a 49-year old male who had been experiencing generalized abdominal pain for 14 months and was found to have a mass on ultrasonography. Further evaluation with Contrast-enhanced Computerized Tomography (CECT) revealed an uneven soft tissue density mass in the retroperitoneal region of the left side. The histopathological examination of the excised mass was suggestive of a mesenchymal tumor, which was further confirmed as leiomyoma by immunohistochemistry.

Clinical discussion

Adrenal Leiomyomas are rare smooth muscle tumors that present with heterogeneously enhancing mass on radiologic imaging. On histopathological examination, spindle cells arranged in lobules and fascicles can be appreciated. Positive staining for desmin and smooth muscle actin in immunohistochemistry confirms the diagnosis.

Conclusion

Identification of the type of tumor in any adrenal mass is challenging pertaining to the non-specific findings on imaging studies. So, prompt surgical resection is the mainstay of the treatment.

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Adrenal leiomyomas are rare tumors.

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These tumors are usually identified incidentally on USG and CT scans of the abdomen & pelvis.

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Histopathological and immunohistochemical studies of the resected tumor mass aid in reaching a definitive diagnosis.

Hirschsprung disease with Edward syndrome: A rare association: A case report

INTRODUCTION AND IMPORTANCE

Edward's syndrome (ES) occurs as a result of trisomy of chromosome 18 and is associated with multisystem congenital anomalies. The association of ES with various gastrointestinal malformations but Hirschsprung disease (HD) is well documented.

CASE PRESENTATION

A female infant on her 5th day of life presented with episodes of bilious vomiting along with abdominal distension and no passage of stool. The child had a small head and prominent occiput, low set abnormal ears, small jaw, upturned nose, widely spaced eyes, small neck with widely spaced nipples, clenched hands with overlapping fingers, flexed big toe, and prominent heels.

CLINICAL DISCUSSION

Edward syndrome is associated with multisystem congenital abnormalities of which gastrointestinal abnormalities make up the most part. The condition can be identified by fetal ultrasound screening. Surgical correction of associated congenital anomalies at different times along with lifelong supportive management is important.

CONCLUSIONS

Edward syndrome can present as Hirschsprung disease as a part of associated gastrointestinal Malformation. Often, early identification and termination of the pregnancy in antenatal life can reduce the suffering. Surgical correction of associated anomalies along with supportive care forms the cornerstone of management. However, the prognosis remains poor.

Ventilator-associated pneumonia among ICU patients in WHO Southeast Asian region: A systematic review

Ventilator-associated pneumonia (VAP) is one of the most frequent ICU-acquired infections and a leading cause of death among patients in Intensive Care Unit (ICU). The South East Asian Region is a part of the world with limited health resources where infectious diseases are still underestimated. We aimed to review the literature in this part of the world to describe incidence, mortality and microbiological evidence of VAP and explore preventive and control strategies. We selected 24 peer-reviewed articles published from January 1, 2000 to September 1, 2020 from electronic databases and manual searching for observational studies among adult patients diagnosed with VAP expressed per thousand days admitted in ICU. The VAP rates ranged from 2.13 to 116 per thousand days, varying among different countries of this region. A significant rate of mortality was observed in 13 studies ranging from 16.2% to 74.1%. Gram negative organisms like Acinetobacter spp., Pseudomonas aeruginosa and Klebsiella pneumoniae and Gram-positive organisms like Staphylococcus aureus and Enterococcus species were frequently found. Our findings suggest an alarming situation of VAP among patients of most of the countries of this region with increasing incidence, mortality and antibiotic resistance. Thus, there is an urgent need for cost effective control and preventive measures like interventional studies and educational programs on staff training, hand hygiene, awareness on antibiotic resistance, implementation of antibiotic stewardship programs and appropriate use of ventilator bundle approach.

Helicobacter pylori healthy South Asians

We aimed to estimate the pooled prevalence of Helicobacter pylori among asymptomatic South Asians based on available literature and highlight the importance of screening asymptomatic individuals and implementing preventive strategies for eradicating H. pylori. Electronic databases such as PubMed and Embase, a regional database of WHO South Asian Region, and gray literature sites were searched for relevant studies from 1983 to 5 May 2020. In addition, references of the included studies were thoroughly searched. The random-effect model was used to calculate the pooled prevalence with a 95% confidence interval (CI) along with subgroup analysis. Analysis of 19 studies showed a pooled prevalence of 56.5%, ranging from 10.3 to 91.7%. In subgroup analysis by country, the highest prevalence rate was reported from Bangladesh (86.3%, 95% CI: 0.806-0.921), whereas the lowest prevalence was from Sri Lanka (10.3%, 95% CI: 0.072-0.135). No differences were found between males and females. Prevalence among children and adolescents was 65.3% (95% CI: 0.529-0.777), greater than adults, 56.9% (95% CI: 0.353-0.785). The prevalence rate showed a decreasing trend upon comparison of studies conducted before and after 2000. Our analysis reveals the high prevalence of H. pylori infection among asymptomatic healthy populations in South Asia, particularly in children and adolescents. Public health awareness and sanitation interventions, pure drinking water, and respective strategies on a policy level to eradicate H. pylori and additional extensive multicentric cohort studies are necessary.

p53 regulates caveolin gene transcription, cell cholesterol, and growth by a novel mechanism

Transcription of the human caveolin gene, directed by a TATA-less promoter, is downregulated in actively dividing cells during S-phase, together with free cholesterol (FC) efflux. It is upregulated by medium low density lipoprotein FC levels in quiescent cells. In this study, a common mechanism has been identified to coordinate the growth- and FC-dependent expression of caveolin. In human skin fibroblasts, transcription factors E2F/DP-1 and Sp1 bound to adjacent consensus sites at -151 to -138 bp of the caveolin promoter DNA sequence in a complex stabilized by tumor suppressor protein p53. Wild-type p53 also bound directly to DNA to a caveolin promoter sequence containing two consensus half-sites (-292 to -283 bp and -273 to -264 bp) for this transcription factor. SREBP-1, previously identified as a transcriptional regulator of caveolin expression in response to FC, mediated its effect via the same E2F/Sp1 site. Overexpression of E2F or p53 increased E2F binding to the -148 to -141 bp site, increased FC efflux, and inhibited cell division. The mutant protein p53(143V-->A) was inactive. Okadaic acid, previously shown to inhibit growth, FC efflux, and caveolin expression, inhibited E2F/Sp1 binding, while higher concentrations of extracellular FC increased it. The present findings provide a molecular link between the cell cycle and FC homeostatic effects of caveolin. These results also describe a novel mechanism of action for p53 in a TATA-less gene promoter and provide further evidence for a significant regulatory role for FC in cell cycle progression.

Intracellular cholesterol transport in synchronized human skin fibroblasts

Normal human skin fibroblasts maintained in serum-containing medium were synchronized with aphidicolin. After removal of inhibitor, free cholesterol (FC) homeostasis was determined at intervals during the following cell cycle. FC mass per cell doubled following S-phase, and reached its maximum well before mitosis. This increase was mainly the result of stimulation of the rate of selective uptake of FC from medium lipoproteins, and reduction of FC efflux. Rates of cholesterol synthesis, endocytosis of intact low-density lipoprotein, and HDL receptor (CLA-1) activity were relatively low and little changed during the cell cycle. The expression of caveolin (structural protein of cell surface caveolae) and caveolar FC were decreased along with FC efflux. To test the hypothesis that regulation of caveolin expression could contribute to changes in FC efflux during cell division, cells were transfected with human caveolin cDNA, synchronized with aphidicolin, and then allowed to divide. In the transfected cells, caveolar FC and FC efflux were both increased. FC accumulation and entry into mitosis were markedly inhibited compared to controls. The contribution of transcriptional regulation to caveolin mRNA levels was determined with a 705 bp caveolin 5'-flanking sequence ligated to the pGL3 luciferase expression vector. Expression of the reporter gene was downregulated at S-phase of synchronized cells. Deletion of a hybrid E2F/ Sp1-like site between -139 and -150 bp abolished this downregulation. These data are consistent with a role for caveolin in cell cycle kinetics, which may be mediated, at least in part, at the transcriptional level.

Two sterol regulatory element-like sequences mediate up-regulation of caveolin gene transcription in response to low density lipoprotein free cholesterol

Caveolae form the terminus for a major pathway of intracellular free cholesterol (FC) transport. Caveolin mRNA levels in confluent human skin fibroblasts were up-regulated following increased uptake of low density lipoprotein (LDL) FC. The increase induced by FC was not associated with detectable change in mRNA stability, indicating that caveolin mRNA levels were mediated at the level of gene transcription. A total of 924 bp of 5' flanking region of the caveolin gene were cloned and sequenced. The promoter sequence included three G+C-rich potential sterol regulatory elements (SREs), a CAAT sequence and a Sp1 consensus sequence. Deletional mutagenesis of individual SRE-like sequences indicated that of these two (at -646 and -395 bp) were essential for the increased transcription rates mediated by LDL-FC, whereas the third was inconsequential. Gel shift analysis of protein binding from nuclear extracts to these caveolin promoter DNA sequences, together with DNase I footprinting, confirmed nucleoprotein binding to the SRE-like elements as part of the transcriptional response to LDL-FC. A supershift obtained with antibody to SRE-binding protein 1 (SPEBP-1) indicated that this protein binds at -395 bp. There was no reaction at -395 bp with anti-Sp1 antibody nor with either antibody at -646 bp. The cysteine protease inhibitor N-acetyl-leu-leu-norleucinal (ALLN), which inhibits SREBP catabolism, superinhibited caveolin mRNA levels regardless of LDL-FC. This finding suggests that SREBP inhibits caveolin gene transcription in contrast to its stimulating effect on other promoters. The findings of this study are consistent with the postulated role for caveolin as a regulator of cellular FC homeostasis in quiescent peripheral cells, and the coordinate regulation by SREBP of FC influx and efflux.

Caveolin mRNA levels are up-regulated by free cholesterol and down-regulated by oxysterols in fibroblast monolayers

In confluent fibroblast monolayers, an increase in the selective uptake of free cholesterol (FC) from plasma low density lipoprotein (LDL) was accompanied by an increase in FC efflux. The rate of FC efflux was proportional to the FC content of the cell surface caveolae and to mRNA levels of caveolin, an FC-binding protein of caveolae. Inhibitors of LDL-FC internalization reduced the increase in caveolin mRNA levels and FC efflux. Oxysterols reduced caveolin mRNA levels, as well as transport of FC to the cell surface and FC efflux. DNA antisense to caveolin reduced caveolin mRNA and inhibited FC efflux. These data suggest that regulation of FC efflux can contribute to cellular FC homeostasis when LDL levels are modified over the physiological range, and they link this regulation to caveolin.