Universal Measure for the Impact of Adiabaticity on Quantum Transitions

Adiabaticity is crucial for our understanding of complex quantum dynamics and thus for advancing fundamental physics and technology, but its impact cannot yet be quantified in complex but common cases where dynamics is only partially adiabatic, several eigenstates are simultaneously populated and transitions between noneigenstates are of key interest. We construct a universally applicable measure that can quantify the adiabaticity of quantum transitions in an arbitrary basis. Our measure distinguishes transitions that occur due to the adiabatic change of populated system eigenstates from transitions that occur due to beating between several eigenstates and can handle nonadiabatic events. While all quantum dynamics fall within the scope of the measure, we demonstrate its usage and utility through two important material science problems-energy and charge transfer-where adiabaticity could be effected by nuclear motion and its quantification will aid not only in unraveling mechanisms but also in system design, for example, of light harvesting systems.

Levels of Autonomous Radiology

Radiology, being one of the younger disciplines of medicine with a history of just over a century, has witnessed tremendous technological advancements and has revolutionized the way we practice medicine today. In the last few decades, medical imaging modalities have generated seismic amounts of medical data. The development and adoption of artificial intelligence applications using this data will lead to the next phase of evolution in radiology. It will include automating laborious manual tasks such as annotations, report generation, etc, along with the initial radiological assessment of patients and imaging features to aid radiologists in their diagnostic and treatment planning workflow. We propose a level-wise classification for the progression of automation in radiology, explaining artificial intelligence assistance at each level with the corresponding challenges and solutions. We hope that such discussions can help us address challenges in a structured way and take the necessary steps to ensure the smooth adoption of new technologies in radiology.

A deep learning approach for automated diagnosis of pulmonary embolism on computed tomographic pulmonary angiography

Background

Computed tomographic pulmonary angiography (CTPA) is the diagnostic standard for confirming pulmonary embolism (PE). Since PE is a life-threatening condition, early diagnosis and treatment are critical to avoid PE-associated morbidity and mortality. However, PE remains subject to misdiagnosis.

Methods

We retrospectively identified 251 CTPAs performed at a tertiary care hospital between January 2018 to January 2021. The scans were classified as positive (n = 55) and negative (n = 196) for PE based on the annotations made by board-certified radiologists. A fully anonymized CT slice served as input for the detection of PE by the 2D segmentation model comprising U-Net architecture with Xception encoder. The diagnostic performance of the model was calculated at both the scan and the slice levels.

Results

The model correctly identified 44 out of 55 scans as positive for PE and 146 out of 196 scans as negative for PE with a sensitivity of 0.80 [95% CI 0.68, 0.89], a specificity of 0.74 [95% CI 0.68, 0.80], and an accuracy of 0.76 [95% CI 0.70, 0.81]. On slice level, 4817 out of 5183 slices were marked as positive for the presence of emboli with a specificity of 0.89 [95% CI 0.88, 0.89], a sensitivity of 0.93 [95% CI 0.92, 0.94], and an accuracy of 0.89 [95% CI 0.887, 0.890]. The model also achieved an AUROC of 0.85 [0.78, 0.90] and 0.94 [0.936, 0.941] at scan level and slice level, respectively for the detection of PE.

Conclusion

The development of an AI model and its use for the identification of pulmonary embolism will support healthcare workers by reducing the rate of missed findings and minimizing the time required to screen the scans.

Observer performance evaluation of the feasibility of a deep learning model to detect cardiomegaly on chest radiographs

Background

Cardiothoracic ratio (CTR) is the ratio of the diameter of the heart to the diameter of the thorax. An abnormal CTR (>0.55) is often an indicator of an underlying pathological condition. The accurate prediction of an abnormal CTR chest X-rays (CXRs) aids in the early diagnosis of clinical conditions.

Purpose

We propose a deep learning (DL)-based model for automatic CTR calculation to assist radiologists with rapid diagnosis of cardiomegaly and thus optimise the radiology flow.

Material and Methods

The study population included 1012 posteroanterior CXRs from a single institution. The Attention U-Net DL architecture was used for the automatic calculation of CTR. An observer performance test was conducted to assess the radiologist’s performance in diagnosing cardiomegaly with and without artificial intelligence assistance.

Results

U-Net model exhibited a sensitivity of 0.80 [95% CI: 0.75, 0.85], specificity >99%, precision of 0.99 [95% CI: 0.98, 1], and a F1 score of 0.88 [95% CI: 0.85, 0.91]. Furthermore, the sensitivity of the reviewing radiologist in identifying cardiomegaly increased from 40.50% to 88.4% when aided by the AI-generated CTR.

Conclusion

Our segmentation-based AI model demonstrated high specificity (>99%) and sensitivity (80%) for CTR calculation. The performance of the radiologist on the observer performance test improved significantly with provision of AI assistance. A DL-based segmentation model for rapid quantification of CTR can therefore have significant potential to be used in clinical workflows by reducing radiologists’ burden and alerting to an abnormal enlarged heart early on.

RING finger protein TOPORS modulates the expression of tumor suppressor SMAR1 in colorectal cancer via the TLR4-TRIF pathway

TOP1‐binding arginine/serine‐rich protein (TOPORS), a really interesting new gene finger protein, has the ability to bind to a palindromic consensus DNA sequence that enables it to function as a potential transcriptional regulator. However, its role in regulating the transcription of cancer‐associated genes is yet to be explored. As Toll‐like receptor 4 (TLR4) agonists are known to regress solid tumors, we observed that lipopolysaccharide (LPS) induces TOPORS via a TLR4‐TIR domain‐containing adapter‐inducing interferon‐β‐dependent pathway, which in turn modulates the transcription of tumor suppressor scaffold/matrix attachment region‐binding protein 1 (SMAR1, also known as BANP). ChIP analysis showed that TOPORS binds on the SMAR1 promoter and its occupancy increases upon LPS treatment. A previous study from our laboratory revealed that SMAR1 acts as a repressor of signal transducer and activator of transcription 3 (STAT3) transcription. Tumor growth, as well as tumor‐associated macrophage polarization, depends on the status of the STAT1:STAT3 ratio. LPS‐induced SMAR1 expression decreases STAT3 expression and also skews the macrophage polarization toward M1 phenotype. In contrast, LPS failed to polarize tumor‐associated macrophages to M1 phenotype in a SMAR1‐silenced condition, which shows the involvement of SMAR1 in dictating the fate of colorectal cancer progression. Identification of the molecular mechanism behind LPS‐mediated tumor regression would be crucial for designing cancer treatment strategies involving bacterial components.

Chromatin remodeling protein SMAR1 regulates adipogenesis by modulating the expression of PPARγ

Adipogenesis is described as the process of conversion of pre-adipocytes into differentiated lipid-laden adipocytes. Adipogenesis is known to be regulated by a myriad of transcription factors and co-regulators. However, there is a dearth of information regarding the mechanisms that regulate these transcription factors and hence control adipogenesis. PPARγ is the master transcriptional regulator of adipogenesis and its expression is essential for adipocyte differentiation. Herein, we identified that scaffold/matrix attachment region-binding protein 1 (SMAR1) negatively regulates adipogenesis. We observed that SMAR1 gets downregulated during adipocyte differentiation and knockdown of SMAR1 promotes lipid accumulation and adipocyte differentiation. Mechanistically, we have shown that SMAR1 suppresses PPARγ through recruitment of the HDAC1/mSin3a repressor complex to the PPARγ promoter. We further identified cell division cycle 20 (cdc20) mediated proteasomal degradation of SMAR1 during adipogenesis. Moreover, knockdown of cdc20 resulted in stabilization of SMAR1 and a reduction in adipocyte differentiation. Taken together, our observations suggest that SMAR1 functions as a negative regulator of adipogenesis by inhibiting PPARγ expression in differentiating adipocytes.

Tumor suppressor SMAR1 regulates PKM alternative splicing by HDAC6-mediated deacetylation of PTBP1

BACKGROUND

Highly proliferating cancer cells exhibit the Warburg effect by regulation of PKM alternative splicing and promoting the expression of PKM2. Majority of the alternative splicing events are known to occur in the nuclear matrix where various MARBPs actively participate in the alternative splicing events. SMAR1, being a MARBP and an important tumor suppressor, is known to regulate the splicing of various cancer-associated genes. This study focuses on the regulation of PKM alternative splicing and inhibition of the Warburg effect by SMAR1.

METHODS

Immunohistochemistry was performed in breast cancer patient samples to establish the correlation between SMAR1 and PKM isoform expression. Further, expression of PKM isoforms upon modulation in SMAR1 expression in breast cancer cell lines was quantified by qRT-PCR and western blot. The acetylation status of PTBP1 was estimated by immunoprecipitation along with its enrichment on PKM pre-mRNA by CLIP in SMAR1 knockdown conditions. The role of SMAR1 in tumor metabolism and tumorigenesis was explored by in vitro enzymatic assays and functional assays upon SMAR1 knockdown. Besides, in vivo tumor formation by injecting adeno-SMAR1-transduced MDA-MB-231 cells in NOD/SCID mice was performed.

RESULTS

The expression profile of SMAR1 and PKM isoforms in breast cancer patients revealed that SMAR1 has an inverse correlation with PKM2 and a positive correlation with PKM1. Further quantitative PKM isoform expression upon modulation in SMAR1 expression also reflects that SMAR1 promotes the expression of PKM1 over tumorigenic isoform PKM2. SMAR1 deacetylates PTBP1 via recruitment of HDAC6 resulting in reduced enrichment of PTBP1 on PKM pre-mRNA. SMAR1 inhibits the Warburg effect, tumorigenic potential of cancer cells, and in vivo tumor generation in a PKM2-dependent manner.

CONCLUSIONS

SMAR1 regulates PKM alternative splicing by causing HDAC6-dependent deacetylation of PTBP1, resulting in reduced enrichment of PTBP1 on PKM pre-mRNA. Additionally, SMAR1 suppresses glucose utilization and lactate production via repression of PKM2 expression. This suggests that tumor suppressor SMAR1 inhibits tumor cell metabolism and tumorigenic properties of cancer cells via regulation of PKM alternative splicing.

Epigenetic Regulation of Adipogenesis in Development of Metabolic Syndrome

Obesity is one of the biggest public health concerns identified by an increase in adipose tissue mass as a result of adipocyte hypertrophy and hyperplasia. Pertaining to the importance of adipose tissue in various biological processes, any alteration in its function results in impaired metabolic health. In this review, we discuss how adipose tissue maintains the metabolic health through secretion of various adipokines and inflammatory mediators and how its dysfunction leads to the development of severe metabolic disorders and influences cancer progression. Impairment in the adipocyte function occurs due to individuals' genetics and/or environmental factor(s) that largely affect the epigenetic profile leading to altered gene expression and onset of obesity in adults. Moreover, several crucial aspects of adipose biology, including the regulation of different transcription factors, are controlled by epigenetic events. Therefore, understanding the intricacies of adipogenesis is crucial for recognizing its relevance in underlying disease conditions and identifying the therapeutic interventions for obesity and metabolic syndrome.

Wnt Signaling and Its Significance Within the Tumor Microenvironment: Novel Therapeutic Insights

Wnt signaling is one of the central mechanisms regulating tissue morphogenesis during embryogenesis and repair. The pivot of this signaling cascade is the Wnt ligand, which binds to receptors belonging to the Frizzled family or the ROR1/ROR2 and RYK family. This interaction governs the downstream signaling cascade (canonical/non-canonical), ultimately extending its effect on the cellular cytoskeleton, transcriptional control of proliferation and differentiation, and organelle dynamics. Anomalous Wnt signaling has been associated with several cancers, the most prominent ones being colorectal, breast, lung, oral, cervical, and hematopoietic malignancies. It extends its effect on tumorigenesis by modulating the tumor microenvironment via fine crosstalk between transformed cells and infiltrating immune cells, such as leukocytes. This review is an attempt to highlight the latest developments in the understanding of Wnt signaling in the context of tumors and their microenvironment. A dynamic process known as immunoediting governs the fate of tumor progression based on the correlation of various signaling pathways in the tumor microenvironment and immune cells. Cancer cells also undergo a series of mutations in the tumor suppressor gene, which favors tumorigenesis. Wnt signaling, and its crosstalk with various immune cells, has both negative as well as positive effects on tumor progression. On one hand, it helps in the maintenance and renewal of the leucocytes. On the other hand, it promotes immune tolerance, limiting the antitumor response. Wnt signaling also plays a role in epithelial-mesenchymal transition (EMT), thereby promoting the maintenance of Cancer Stem Cells (CSCs). Furthermore, we have summarized the ongoing strategies used to target aberrant Wnt signaling as a novel therapeutic intervention to combat various cancers and their limitations.

SMAR1 favors immunosurveillance of cancer cells by modulating calnexin and MHC I expression

Down-regulation or loss of MHC class I expression is a major mechanism used by cancer cells to evade immunosurveillance and increase their oncogenic potential. MHC I mediated antigen presentation is a complex regulatory process, controlled by antigen processing machinery (APM) dictating immune response. Transcriptional regulation of the APM that can modulate gene expression profile and their correlation to MHC I mediated antigen presentation in cancer cells remain enigmatic. Here, we reveal that Scaffold/Matrix-Associated Region 1- binding protein (SMAR1), positively regulates MHC I surface expression by down-regulating calnexin, an important component of antigen processing machinery (APM) in cancer cells. SMAR1, a bonafide MAR binding protein acts as a transcriptional repressor of several oncogenes. It is down-regulated in higher grades of cancers either through proteasomal degradation or through loss of heterozygosity (LOH) at the Chr.16q24.3 locus where the human homolog of SMAR1 (BANP) has been mapped. It binds to a short MAR region of the calnexin promoter forming a repressor complex in association with GATA2 and HDAC1. A reverse correlation between SMAR1 and calnexin was thus observed in SMAR1-LOH cells and also in tissues from breast cancer patients. To further extrapolate our findings, influenza A (H1N1) virus infection assay was performed. Upon viral infection, the levels of SMAR1 significantly increased resulting in reduced calnexin expression and increased MHC I presentation. Taken together, our observations establish that increased expression of SMAR1 in cancers can positively regulate MHC I surface expression thereby leading to higher chances of tumor regression and elimination of cancer cells.

Neuritic Leprosy; An Intriguing Re-visit to a Forbidden Ailment

Leprosy is a chronic infectious disease that presents with varied manifestations. Pure neuritic leprosy is one of the rarest forms of the disease which is characterized by nerve involvement without the characteristic cutaneous stigmata. Eleven year old, healthy male presented with progressively increasing painful swelling at the medial aspect of the arm near to the right elbow joint with difficulty in extending right ring and little fingers at interphalangeal joint and numbness in the same region for last 1 year with no cutaneous abnormalities. Physical examination revealed 6x3 cm firm, tender lesion 3 cm proximal to the right elbow joint with positive tinel's sign, without signs of inflammation, along with characteristic claw hand deformity of right hand and atrophy of hypothenar and interossei muscle. Electro-diagnostic testing revealed findings consistent with a right ulnar axonal neuropathy above the elbow. Magnetic resonance imaging revealed well defined heterogeneously hyper intense linear lesion along the course of thickened ulnar nerve in the distal arm extending posterior to the medial condyle. It also showed an oval shaped lesion (2.1x1.0 cm) arising from the same segment of the nerve, without any bony or muscular involvement of that area. The patient underwent surgical exploration and ulnar nerve decompression with biopsy. Pathology revealed necrotizing granulomatous inflammatory acid fast bacilli stain negative lesion, which was histologically consistent with caseous abscess caused by tuberculoid leprosy, pathognomonic for Hansen's disease. He has been started on antibiotic therapy and is referred to leprosy center for further course of management. Pure neuritic leprosy, though rare, should be considered as differential diagnosis in cases presenting with peripheral neuropathy at leprosy-endemic areas. Prompt diagnosis and treatment is imperative to prevent permanent neurological injury.

An Assessment of a Public Health Initiative of Homeopathy for Primary Teething

BACKGROUND

 During primary teething, children suffer from running nose, mild fever, diarrhoea and other mild irritations and inflammations. A public health programme, 'Homoeopathy for the Healthy Child', was undertaken on a pilot basis focusing on promotion of healthy teething by provision of home-based care through six pre-identified homeopathic medicines for complaints commonly observed during primary teething. This article assesses the feasibility of this programme and reports the impact of this initiative on teething profile in children and episodes of diarrhoea and upper respiratory tract infection (URTI).

MATERIALS AND METHODS

 Accredited Social Health Activists (ASHAs) were trained in child care and usage of a kit comprising six medicines, namely Calcarea phosphoricum 6X (CP), Ferrum phosphoricum 3X, Magnesium phosphoricum 6X, Belladonna 30C, Chamomilla 30C and Podophyllum 30C. Calcarea phosphoricum was given regularly to each participating child from 6 months to 1 year of age. Home-based care for diarrhoea, URTI and mild fever was provided by ASHAs using the other five medicines in the kit. Dentition pattern and diarrhoea/URTI episodes were recorded over a period of the next 12 months.

RESULTS

 Eleven thousand four-hundred and twenty-six children were followed up regularly. Amongst those who enrolled at 6-7 months, a larger proportion of children were approaching expected teething in successive months as compared with children enrolled at 12 months, thus indicating that teething delays, if any, were overcome during this period. Incidence of diarrhoea and URTI showed decrease in the months after enrolment. Children responded favourably to the medicines given by ASHAs at the time of diarrhoea/URTI episodes, and ASHAs expressed satisfaction with the programme.

CONCLUSION

 An approach with regular use of CP and home-based care with homeopathy through health workers for common problems in teething children is acceptable to the community and enhances outreach of services to the public at large. Observations in terms of the healthy teething period may be further validated through studies of homeopathy with suitable comparator group.

Pre-exposure prophylaxis: awareness, acceptability and risk compensation behaviour among men who have sex with men and the transgender population

OBJECTIVES

This exploratory study examined the facilitators of and barriers to acceptance of pre-exposure prophylaxis (PrEP) and potential risk compensation behaviour emerging from its use among men who have sex with men (MSM) and transgender individuals (TGs) in India.

METHODS

A questionnaire was administered to 400 individuals registered with a targeted intervention programme. Logistic regression models were used to identify facilitators of and barriers to PrEP acceptance.

RESULTS

The respondents consisted of 68% MSM and 32% TGs. Risk behaviour categorization identified 40% as low risk, 41% as medium risk and, 19% as high risk for HIV infection. About 93% of the respondents were unaware of PrEP, but once informed about it, 99% were willing to use PrEP. The facilitators of PrEP acceptance were some schooling [odds ratio (OR) 2.16; P = 0.51], being married or in a live-in relationship (OR 2.08; P = 0.46), having a high calculated risk (OR 3.12; P = 0.33), and having a high self-perceived risk (OR 1.8; P = 0.35). Increasing age (OR 2.12; P = 0.04) was a significant barrier. TGs had higher odds of acceptance of PrEP under conditions of additional cost (OR 2.12; P = 0.02) and once-daily pill (OR 2.85; P = 0.04). Individuals identified as low risk for HIV infection showed lower odds of potential risk compensation, defined as more sexual partners (OR 0.8; P = 0.35), unsafe sex with new partners (OR 0.71; P = 0.16), and decreased condom use with regular partners (OR 0.95; P = 0.84), as compared with medium-risk individuals. The associations, although not statistically significant, are nevertheless important for public health action given the limited scientific evidence on PrEP use among MSM and TGs in India.

CONCLUSIONS

With high acceptability and a low likelihood of risk compensation behaviour, PrEP can be considered as an effective prevention strategy for HIV infection among MSM and TGs in India.

IL-4 promotes asymmetric dimethylarginine accumulation, oxo-nitrative stress, and hypoxic response-induced mitochondrial loss in airway epithelial cells

BACKGROUND

Obesity is known to increase asthma risk and severity. Increased levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, are associated with mitochondrial toxicity, asthma, and metabolic syndrome. IL-4 upregulates the expression of protein arginine methyltransferases, which are essential for ADMA formation. Importantly, cross-talk between IL-4, ADMA, and mitochondrial dysfunction could explain how obesity and IL-4 can synergize to exacerbate allergic inflammation.

OBJECTIVE

We sought to investigate how IL-4, a key asthma-associated cytokine, can influence ADMA-related effects on lungs.

METHODS

BEAS2B (bronchial epithelial) cells were treated with IL-4 followed by ADMA and investigated for oxo-nitrative stress and resultant mitochondrial toxicity after 48 hours by using flow cytometry, confocal imaging, immunoblotting, and fluorimetric assays.

RESULTS

IL-4-induced mitotoxicity in BEAS2B cells was significantly higher in the presence of exogenous ADMA. IL-4 treatment led to proteolytic degradation of dimethylarginine dimethylaminohydrolase 2, which catabolizes ADMA. IL-4 pretreatment was associated with increased intracellular ADMA accumulation and increased ADMA-induced mitotoxicity. Airway epithelial cells treated with IL-4 followed by ADMA showed exaggerated oxo-nitrative stress and potent induction of the cellular hypoxic response, despite normoxic conditions. The hypoxic response was associated with reduced mitochondrial function but was reversible by overexpression of the mitochondrial biogenesis factor, mitochondrial transcription factor A.

CONCLUSION

We conclude that IL-4 promotes intracellular ADMA accumulation, leading to mitochondrial loss through oxo-nitrative stress and hypoxic response. This provides a novel understanding of how obesity, with high ADMA levels, and asthma, with high IL-4 levels, might potentiate each other and highlights the potential of mitochondrial-targeted therapeutics in obese subjects with asthma.

Impact of intensified case-finding strategies on childhood TB case registration in Nepal

SETTING

Seven intervention districts with intensified childhood tuberculosis (TB) case-finding strategies implemented by a non-governmental organisation and seven control districts under the National Tuberculosis Programme, Nepal.

OBJECTIVES

To assess the differences in childhood TB case registrations and case registration rates per 100 000 population between two time periods (Year 1 = March 2012-March 2013 and Year 2 = March 2013-March 2014) in intervention and control districts.

DESIGN

Retrospective record review using routinely collected data.

RESULTS

Childhood TB cases increased from 271 to 360 between Years 1 and 2 in the intervention districts (case registration rate from 18.2 to 24.2/100 000) and from 97 to 113 in the control districts (13.4 to 15.6/100 000): the increases were significantly higher in the intervention districts compared with the control districts. The increases were also significantly higher in children aged 0-4 years and in those with smear-negative pulmonary TB and extra-pulmonary TB. Of the various case-finding strategies, household contact screening, private-public mix services and mobile health chest camps produced the highest yield of TB.

CONCLUSION

A package of intensified case-finding strategies in children was associated with an increase in childhood TB case registrations in Nepal. Additional diagnostic approaches to increase case registrations also need to be considered.

Perfluoropropane (C3F8) injection for Descemet's membrane detachment in cataract surgery

BACKGROUND

Descemet's membrane (DM) detachment is an important cause of surgery related corneal edema that may lead to corneal decompensations and marked reduction in visual acuity if not identified and treated promptly. We prescent a case of postoperative Descemet's membrane detachment that occurred after complicated manual small incisional cataract surgery. Descemetopexy in post-cataract surgery descemet's membrane detachment has not yet been reported in Nepal.

CASE

A 45 year old female underwent manual small incision cataract surgery of the right eye. Intraoperatively, there was descemet's membrane detachment so: anterior chamber tamponade with air was done. She was discharged with a visual acuity of 6/24. But on the eighth postoperative day, her visual acuity had decreased to 1/60 in right eye with corneal edema, detached descemet's membrane and descemet's folds. Hence was re-admitted for repositioning of descemet's membrane with C3F8 (14% gas mixed with air). The procedure successfully reattached the descemet's membrane. Corneal edema regressed and the gas bubble resolved after 15th day of the surgery. Patient's visual right acuity was 6/36 in right eye and the intraocular pressure was 12mmhg.

CONCLUSION

DM detachment should not be taken lightly because of the potential for grave visual outcome. One needs to examine carefully, as the signs of DM detachment can be subtle and may be masked by corneal edema. During the past few years, intracameral injection with perfluoropropane (C3F8) gas has also gained increasing acceptance as an efficient and effective treatment option for Descemet's membrane detachments.

An approach to diagnostic dilemma in thyroid cytopathology

Journal of Pathology of Nepal (2012) Vol. 2, 338-339DOI: http://dx.doi.org/10.3126/jpn.v2i4.6892

Cavity enhanced stimulated Brillouin scattering in an optical chip for multiorder Stokes generation

We report the first demonstration of on-chip cascaded stimulated Brillouin scattering (SBS). Cascaded SBS is characterized in a 4 cm long chalcogenide (As₂S₃) rib waveguide where the end facet reflections provide a monolithic Fabry-Perot (FP) resonator. The presence of the FP cavity reduces the Brillouin gain threshold, which enables observation of cascaded SBS at reduced pump powers. We observe up to three orders of Stokes waves in the backscattered signal at a coupled peak power of 1.34 W. Anti-Stokes waves due to four-wave mixing between the pump and the Stokes wave were observed in the forward spectrum.

Non Surgical Management of Pseudoaneurysms

BACKGROUND

The incidence of pseudoaneurysm has increased due to the large number of vascular procedures performed and the widespread use of anticoagulation therapy during procedures. Non-invasive methods for management of pseudoaneurysms comprise of ultrasound guided compression (USGC), thrombin therapy, arterial embolisation and endovascular stent graft insertion. We discuss our experience in the management of fourteen cases of pseudoaneurysms using non surgical techniques.

METHODS

During a two year period, fourteen patients presenting with pseudoaneurysms of different regions were treated.

RESULT

Of the fourteen patients, eleven were iatrogenic and three were attributable to trauma. There were six cases of pseudoaneurysms of the femoral artery following coronary angiography studies. One patient developed pseudoaneurysm of right popliteal artery after external fixation of fracture right tibia and fibula. Three cases of renal artery pseudoaneurysms occurred following percutaneous nephrolithotomy (PCNL). The cases were evaluated using a varying combination of color doppler, multidetector computerised tomography (CT) and angiography. These cases were treated with ultrasound guided compression (USGC), stent graft and coil embolisation. The selection of method was based on the location and size of pseudoaneurysms besides the efficacy of the technique. USGC was performed in seven, of which six were in the femoral artery and one supraorbital. The technique was unsuccessful in three of the seven, wherein stent graft was deployed in the femoral artery. Coil embolisation was utilised in three cases of renal artery pseudoaneurysms following PCNL.

CONCLUSION

Follow up with color doppler and CT angiography within a week, 6 and 12 months period showed successful regression of pseudoaneurysms in all cases.

A study of practical parameters and their relative importance as perceived by various stakeholders in clinical trials

A contract research organization (CRO) is a company which conducts a Good Clinical Practice (GCP) in clinical trial. There are literally hundreds of CROs worldwide employing a workforce of nearly 100,000 professionals. The project proposes the study of practical parameters and their relative importance as perceived by the various stakeholders in clinical trials. The survey was conducted in Bangalore and New Delhi. Primary market data was obtained by primary market research which included 80 clinical trial stakeholders by having a preliminary communication with them, followed by administering a questionnaire along with prior permission. There were 15 Sponsors/ CROs, 27 Investigators /Monitors and 38 Ethics committee members involved in the study. It was shown from the study that a clinical investigator involved in a clinical trial is responsible for ensuring that an investigation is conducted according to the signed investigator statement, the investigational plan, and applicable regulations; for protecting the rights, safety, and welfare of the subjects under the investigator’s care; and for the control of drugs under investigation. It was also shown from the study that the sponsors of a clinical trial carry the ultimate responsibility for the initiation, management and financing of the clinical trial. The study has identified a specific training need at the level of the individual stakeholder to perform a particular job function and to identify the actual practical parameters in the Indian context important for the conduction of clinical trials (GCP) with respect to the different stakeholders, to determine the relative importance of these parameters as perceived by various stakeholders involved in clinical trials, and to identify the relative contributions of different stakeholders to the success/ satisfactory conduct of a clinical trial.

Extraskeletal Ewing's sarcoma family of tumours in adults: analysis of 57 patients from a single institution

AIMS

Extraskeletal Ewing's sarcoma (EES) is a rare form of soft tissue sarcoma. The aim of the present study was to assess the outcome and the prognosis of adult patients presenting with EES treated with multi-modality therapy.

MATERIALS AND METHODS

All EES patients older than 15 years referred to our institution between January 1995 and December 2004 were reviewed. In total, 57 patients were identified. Their median age at diagnosis was 20 years (range 15-57).

RESULTS

The median size of the primary tumour was 11 cm (range 4-30 cm). Eighteen patients (31%) had metastatic disease at initial presentation. Wide surgical resection with negative margins was achieved in 23 cases (40%). Chemotherapy consisting of vincristine, adriamycin, ifosfamide, actinomycin D was given in 50 patients (88%). Radiotherapy was delivered in 37 patients (65%). Forty-one patients (72%) achieved complete remission and 16 (28%) progressed on therapy. Twenty-one patients (51%) relapsed. Local recurrence was encountered in 15 patients (36%). At a median follow-up of 46 months (range 6-143 months), the 5-year event-free survival and overall survival rates were 35 and 47%, respectively. Metastases at presentation, tumour size and surgical resection margin associated significantly with overall survival and event-free survival.

CONCLUSION

EES is an aggressive type of tumour with a high incidence of local recurrence and distant metastasis. This series showed that the outcome of adult EES is not unlike that of skeletal Ewing's sarcoma in terms of response to multi-modality treatment and the prognostic factors influencing treatment outcome. Adequate surgical resection, aggressive chemotherapy and adjuvant local radiation therapy, when indicated, constitute the optimal treatment to achieve the best results in this rare type of disease.

Comparative attitude and plans of the medical students and young Nepalese doctors

INTRODUCTION

Many doctors are leaving Nepal to work abroad. To understand this problem better, we decided to study the attitude and plans of young doctors and medical students.

MATERIALS AND METHODS

This cross-sectional study was conducted at Kathmandu Medical College involving 65 first year medical students, 100 interns and 100 house officers. The data collected was entered in Microsoft excel and analysed by SPSS (Statistical Package for Social Sciences) programme. Chi-square test was used to compare two proportions. Significance level was set at 5%.

RESULTS

Only 2% house officers said that their job prospects were excellent as compared to 22.4% of students, whereas 20% house officers as compared to 9% students thought job prospects in Nepal were poor (p= 0.003). Eighty two percent of students thought that a doctor's service to his country was very important as compared to 51% of interns (p= 0.001) and 58% of house officers. Forty percent of students, 58% of interns and 48% of house officers (no statistical significance between the three groups) planned to migrate to a developed country after graduation. Eighty eight percent of students, 89% interns and 74% of house officers (no statistical significant differences between the three groups) were of the opinion that improving career opportunities or working environment of the doctor could make the profession more attractive.

CONCLUSION

Although majority of students, interns and house officers were of the opinion that a doctor's service to his community/country was very important, almost half of them still planned to migrate to a developed country after graduation. Improving the chances of professional advancement and professional working environment can make the profession more attractive, and therefore, may decrease this tendency for brain drain from our country.

Treatment of aggressive fibromatosis: the experience of a single institution

AIMS

Aggressive fibromatosis is a locally aggressive infiltrative low-grade tumour, although pathologically benign, and it does not metastasise, yet it can cause serious local distressing symptoms by virtue of local destruction and impairment of local function. The aim of this study was to emphasise the role of radiotherapy and adequate surgery in the treatment of fibromatosis in patients presenting with newly diagnosed or recurrent disease and to analyse our treatment results over 15 years for this rare tumour type.

MATERIALS AND METHODS

Fifty-four patients with confirmed diagnosis of aggressive fibromatosis treated at King Faisal Specialist Hospital between 1990 and 2006 were identified from our local cancer registry. Forty-seven patients had surgery: complete resection (R0) in 20 patients, incomplete surgery (R1/2) in 27 patients, and seven patients had biopsy only. Forty-five patients were treated with radiotherapy: 38 patients were treated with postoperative radiotherapy, three patients were treated with preoperative radiotherapy and four patients had radiotherapy as the only treatment. The radiotherapy dose ranged between 45 and 60Gy (median 50.4Gy). Three patients did not receive any form of treatment apart from biopsy, but were still included in the final analysis.

RESULTS

Fifty-two per cent (28/54 patients) of our patient population had tumour recurrence when first presented to King Faisal Specialist Hospital. The median age was 29.5 years (range 2-63 years). The most common site of involvement was the extremities (28 patients). Among the 54 patients (with primary and recurrent presentation) there were 10 local recurrences, all of which were within the original primary site. The 5-year progression-free survival and overall survival rates for the whole group were 75 and 95%, respectively. Univariate and multivariate Cox regression analysis showed that the depth of invasion significantly affected progression-free survival.

CONCLUSION

Aggressive fibromatosis is effectively treated with surgery and postoperative radiotherapy. Patients first presenting with tumour recurrence may still have local tumour control comparable with newly diagnosed patients.

Heterozygous disruption of Flk-1 receptor leads to myocardial ischaemia reperfusion injury in mice: application of affymetrix gene chip analysis

This study addresses an important clinical issue by identifying potential candidates of vascular endothelial growth factor (VEGF) signalling through the Flk-1 receptor that trigger cardioprotective signals under ischaemic stress. Isolated working mouse hearts of both wild-type (WT) and Flk-1^+/− were subjected to global ischaemia (I) for 30 min. followed by 2 hrs of reperfusion (R). Flk-1^+/− myocardium displayed almost 50% reduction in Flk-1 mRNA as examined by quantitative real-time RT-PCR at the baseline level. Flk-1^+/− mouse hearts displayed reduction in left ventricular functional recovery throughout reperfusion (dp/dt 605 versus 884), after 2 hrs (P < 0.05). Coronary (1.9 versus 2.4 ml) and aortic flow (AF) (0.16 versus 1.2 ml) were reduced in Flk-1^+/− after 2 hrs of reperfusion. In addition, increased infarct size (38.4%versus 28.41%, P < 0.05) and apoptotic cardiomyocytes (495 versus 213) were observed in Flk-1^+/− knockout (KO) mice. We also examined whether ischaemic preconditioning (PC), a novel method to induce cardioprotection against ischaemia reperfusion injury, through stimulating the VEGF signalling pathway might function in Flk-1^+/− mice. We found that knocking down Flk-1 resulted in significant reduction in the cardioprotective effect by PC compared to WT. Affymetrix gene chip analysis demonstrated down-regulation of important genes after IR and preconditioning followed by ischaemia reperfusion in Flk-1^+/− mice compared to WT. To get insight into the underlying molecular pathways involved in ischaemic PC, we determined the distinct and overlapping biological processes using Ingenuity pathway analysis tool. Independent evidence at the mRNA level supporting the Affymetrix results were validated using real-time RT-PCR for selected down-regulated genes, which are thought to play important roles in cardioprotection after ischaemic insult. In summary, our data indicated for the first time that ischaemic PC modifies genomic responses in heterozygous VEGFR-2/Flk-1 KO mice and abolishes its cardioprotective effect on ischaemic myocardium.

Segmentation and grading of brain tumors on apparent diffusion coefficient images using self-organizing maps

An accurate computer-assisted method to perform segmentation of brain tumor on apparent diffusion coefficient (ADC) images and evaluate its grade (malignancy state) has been designed using a mixture of unsupervised artificial neural networks (ANN) and hierarchical multiresolution wavelet. Firstly, the ADC images are decomposed by multiresolution wavelets, which are subsequently selectively reconstructed to form wavelet filtered images. These wavelet filtered images along with FLAIR and T2 weighted images have been utilized as the features to unsupervised neural network - self organizing maps (SOM) - to segment the tumor, edema, necrosis, CSF and normal tissue and grade the malignant state of the tumor. A novel segmentation algorithm based on the number of hits experienced by Best Matching Units (BMU) on SOM maps is proposed. The results shows that the SOM performs well in differentiating the tumor, edema, necrosis, CSF and normal tissue pattern vectors on ADC images. Using the trained SOM and proposed segmentation algorithm, we are able to identify high or low grade tumor, edema, necrosis, CSF and normal tissue. The results are validated against manually segmented images and sensitivity and the specificity are observed to be 0.86 and 0.93, respectively.

Multidetector CT Evaluation in Arterial Stenting

BACKGROUND

Multidetector CT (MDCT) represents breakthrough in CT technology, significantly improving CT Angiography applications.

METHODS

Twenty one patients with aortoiliac & branch aneurysms or stenosis were evaluated by Digital Subtraction Angiography (DSA) and Multidetector CT (MDCT) before and after endovascular repair.

RESULTS

There were eight cases of aortic & branch aneurysms and 13 with stenosis. Four cases had aortic aneurysms, while one case had left subclavian artery aneurysm, thoracic aneurysm, femoral and popliteal artery pseudoaneurysms. Of the 13 cases with stenotic lesions, iliac stenosis was seen in eight patients. The others included carotid, vertebral, aortic, renal and aortic bifurcation stenotic. MDCT offered accurate information on shape and size of aneurysm, shape and patency of graft, the presence or absence of perigraft thrombosis or endoleaks, while in stenotic lesions it provided useful information on shape of graft, its location, its patency and the presence and quantity of distal flow.

CONCLUSION

MDCT was found to be a potentially useful modality during initial evaluation and follow up of patient undergoing endovascular repair.

An unusual case of an intramuscular lipoma of the pectoralis major muscle simulating a malignant breast mass

INTRODUCTION

Intramuscular lipomas of the pectoralis major muscle are rare and may mimic malignant breast tumours.

CLINICAL PICTURE

A 58-year-old Chinese woman presented with a 2- year history of an enlarging left breast mass. Clinical examination revealed a palpable hard mass in the left breast.

TREATMENT

Standard mammographic views revealed a radiolucent mass deep in the left pectoralis major muscle. The mass was homogeneously hypoechoic with smooth margins on ultrasound.

OUTCOME

Surgical excision of the mass was performed. Histological diagnosis was an intramuscular lipoma of the left pectoralis major muscle.

CONCLUSIONS

Recognition of the radiolucent density and submammary location of a pectoralis major muscle lipoma is important as it allows the correct diagnosis to be made.

The supracondylar femoral nail in tibia

We have found the intramedullary supracondylar femoral nail to be useful in special situations involving the tibia: proximal tibial fractures and nonunions, intercalary resections for tumors in the proximal or distal tibial diaphysis, and tibio-talo-calcaneal arthrodeses. We report on ten such cases.

Turn-up bone flap for lengthening the below-knee amputation stump

When amputation just below the knee becomes necessary after extensive loss of bone from the tibia and of anterior soft tissue in the treatment of tumours, fractures or infection, the remaining proximal tibia may be too short for a below-knee prosthesis, although the knee may be normal. We have included the distal tibia or foot in a long posterior flap by turning it up thus increasing the length of a very short proximal tibial stump. The knee is thereby saved, allowing satisfactory use of a below-knee prosthesis. This technique is particularly applicable when the distal leg is normal and well vascularised. Five procedures have been undertaken. We present two illustrative cases.

Routine abdominal and pelvic ultrasound examinations: an audit comparing radiographers and radiologists

An audit of 202 routine abdominal and pelvic ultrasound examinations was carried out to evaluate the clinical performance and interpretation of these scans by radiographers and compare them with radiologists, and to investigate the extended role of radiographers in performing these scans. Each scan was first performed by a radiographer and then repeated by the radiologist. The findings were subsequently compared and any discrepancy resolved by re-scanning the patient with or without the involvement of an independent radiologist, or by follow-up of the patient by other imaging studies. In 158 (78.2%) scans, there was complete agreement between the radiographer's and radiologist's findings. In 44 scans (21.8%), there was incomplete agreement--there were 108 abnormal findings in these scans with incomplete agreement/discrepancy in 53 abnormalities. Overall, the accuracy of radiographers was 92.0% and radiologists was 91.7%; however, the accuracy rates were 94.0% and 96.4%, respectively, when minor abnormal findings without significant influence on the patient's clinical outcome were excluded.

Modular megaprosthesis for proximal femoral tumors

Fifteen patients with proximal femoral tumors had resection and limb salvage with an uncemented Kotz (HMRS) megaprosthesis. There were five osteosarcomas, four chondrosarcomas, one hemangioendothelioma, three fibrosarcomas, and two Ewing's sarcomas. The mean follow-up was 6.7 (range 3-10) years. Two patients died of causes not related to the prosthesis. The postoperative Musculoskeletal Tumor Society score (MSTS) score was 19 (range 12-26) for the remaining 13 patients. There were one aseptic loosening, two infections, and one local recurrence. The most frequent complication was hip dislocation at 20%. Reconstruction of proximal femoral tumors with a modular megaprosthesis is a good procedure, but hip instability remains a major problem.

Pelvic limb-salvage surgery for malignant tumors

Thirteen patients with primary malignant tumors of the pelvis underwent internal hemipelvectomy. The diagnoses were: Ewing's sarcoma 7, osteosarcoma 4, chondrosarcoma 1, and malignant fibrous histiocytoma 1. No megaprostheses or massive allografts were used for reconstruction. Six patients underwent resection only with no reconstruction, 5 had strut grafts inserted to restore the pelvic ring, 1 had an autoclaved autograft of the acetabulum and 1 had an ilio-femoral arthrodesis. No patients were lost to follow-up. Nine patients died from their disease after an average of 23 months (range 2 to 72 months). The 4 survivors (3 free of disease) have an average follow-up of 84 months (range 60 to 120 months).

Limb salvage for proximal tibial tumours using a modular prosthesis

We report early results after the resection of proximal tibial tumours followed by reconstruction using a modular prosthesis. The indication for wide resection was a malignant tumour in 13 patients, and a neglected giant cell tumour in 2. There were no mechanical failures during an average follow-up of 3.5 years. However, there were 5 peroneal nerve palsies, 1 complete sciatic nerve palsy, 1 vascular injury leading to an above knee amputation, and 2 deep prosthetic infections. There were 2 superficial skin necroses and 1 fracture proximal to the femoral prosthetic component. The mean post-operative Musculo-Skeletal Tumour Society (MSTS) score in 12 patients who still had their prosthesis in situ was 18.3 out of a possible total of 30 (range: 10-28). Limb salvage surgery in the proximal tibia has a high early complication rate even with the use of modern implants and improved techniques.

Treatment of nonunion around the olecranon fossa of the humerus by intramedullary locked nailing

Nonunion of fractures of the olecranon fossa of the humerus presents a difficult surgical problem. The distal fragment is usually small and osteoporotic and stable fixation is not easy to achieve. We describe a modification of the technique of locked nailing by which the distal aspect of the nail is placed in the subchondral region of the trochlea. Good results were obtained in seven out of eight patients with this technique.

Treatment of nonunion around the olecranon fossa of the humerus by intramedullary locked nailing

Nonunion of fractures of the olecranon fossa of the humerus presents a difficult surgical problem. The distal fragment is usually small and osteoporotic and stable fixation is not easy to achieve. We describe a modification of the technique of locked nailing by which the distal aspect of the nail is placed in the subchondral region of the trochlea. Good results were obtained in seven out of eight patients with this technique.

CT-GUIDED FNAC AND BIOPSY : OUR EXPERIENCE

Twenty five patients with mass lesions in the chest, abdomen, pelvis, and paraspinal region underwent contrast enhanced computed tomographic scan (CT Scan) followed by CT guided FNAC or Tru-cut biopsy. CT was found to be extremely valuable in ensuring needle placement within the lesion. It also helped in avoiding the necrotic areas and obtaining tissue from an area most likely to yield an adequate sample. A post-procedure scan helped in ruling out post-procedure complications.

Genital burns and vaginal delivery

Obstetric complications may result from burn scarring in the genital area. Women in developing countries typically squat around cooking fires, and burns are common. This recent case in Nepal describes obstructed labor in a young woman whose genital area had extensive scarring from a cooking fire injury. Proper antenatal assessment by health care providers can reduce the risk to mothers and infants of the consequences of a birth canal damaged or obstructed by burn scarring.

Renal parameters during infancy

In a prospective study we estimated common renal parameters in 48 full term normal neonates, of which 15 were also tested at 6 months and 12 months of age. The mean levels of serum creatinine, were high at birth (0.73 mg/dl) but normal for age at 6 and 12 months; uric acid followed a similar trend. The blood pH and bicarbonate were low at birth (7.28 and 20.36 mEq/L, respectively) reached normal adult values by 12 months; chloride levels were high at birth (110 +/- 5 mEq/L) and normal at 6 months. The plasma renin activity was higher than normal all throughout the first year (27.1, 416.8, 64.8 ng/ml/hr by RIA). Plasma aldosterone values were high at birth (1387.5 pg/ml) and reached normal level (301.6) at 12 months. Renal length and volume as assessed by ultrasonography compared well with American standards. Urinary constituents were variable due to breast feeding up to 6 months and varied diet during the weaning period. This study shows that mild metabolic acidosis and hyperchloremia due to immaturity of renal acidification mechanism and high renin and aldosterone levels due to partial nonresponsiveness of distal tubules are normal variables in babies from birth to 6 months. The levels of serum creatinine and uric acid are high at birth and in assessing renal functions this should be borne in mind.

Therapeutic action of acetylcholine in malathion toxicity

Administration of malathion to the developing Philosamia ricini larvae induces accumulation of acetylcholine, marked inhibition of acetylcholinesterase activity, depletion of all nutrients, heavy weight loss and high mortality. Pre-treatment of the larvae with acetylcholine via feed, reduces malathion toxicity and conversely, feeding of acetylcholine to malathion-treated larvae reverses the toxic effects. Resumption of normal control feed to malathion-treated insects results in higher mortality than in insects fed acetylcholine after exposure to malathion. This emphasizes the therapeutic action of acetylcholine. Feeding of a mixture of equal quantities of malathion and acetylcholine recorded significantly lower mortality among insects in comparison to those fed malathion alone. This further supports the protective action of acetylcholine. Reversal of malathion toxicity and the protective action of acetylcholine have been attributed to the mediation of choline, an essential insect vitamin that gets released as a catabolic product of acetylcholine.