The Montgomery T-tube: anaesthetic problems and solutions

The Montgomery T-tube is a device used as a combined trachealstent and an airway after laryngotracheal surgery. The deviceis used mostly in specialist centres for head and neck surgery,and therefore, many anaesthetists may be unfamiliar with itsuse. The Montgomery T-tube presents the anaesthetist with challengesboth during its surgical insertion when acute loss of the airwaymight occur and also during induction of anaesthesia in patientswho have such a tube in situ. Anaesthetists who are unfamiliarwith the tube may have to resort to ingenious ways of copingwith the problems of a shared airway with a T-tube, which doesnot have a suitable adaptor for a standard catheter mount, aswell as controlling and maintaining ventilation through thedevice. Safe management of such patients requires careful planning.We describe the anaesthetic management of two cases to illustratethe problems associated with Montgomery tubes. Br J Anaesth 2001; 87: 787–90     

Growth inhibition of astrocytoma cells by farnesyl transferase inhibitors is mediated by a combination of anti-proliferative, pro-apoptotic and anti-angiogenic effects

While 25% of human cancers harbor oncogenic Ras mutations, such mutations are not found in astrocytomas. We have previously demonstrated that the activation of receptor tyrosine kinases expressed by malignant human astrocytoma cells and specimens results in functional upregulation of the Ras signalling pathway and increased levels of activated Ras*GTP. Farnesyl transferase inhibitors (FTIs) are promising anti-cancer agents in early clinical trials, which may exert their effect through pharmacological inhibition of the Ras signalling pathway. In this study we establish the anti-tumorigenic properties of the FTI L-744,832 against a panel of malignant human astrocytoma cell lines. Furthermore, we demonstrate the multiple mechanisms by which L-744,832 exerts its effect. L-744,832 demonstrates both cytostatic and cytotoxic effects on astrocytoma cells, and cells expressing a truncated constitutively phosphorylated Epidermal Growth Factor Receptor common in high-grade astrocytomas (EGFRvIII/p140EGF-R) demonstrate increased sensitivity to the agent. L-744,832 is capable of inducing apoptosis in astrocytoma cells under anchorage-dependent conditions; this process occurs in a p53-independent manner and is associated with increased expression of Bax and Bak. L-744,832 also induces cell cycle arrest at both the G1/M and G2/S checkpoints; this process is also independent of p53 mutational status. Cell cycle arrest in drug-treated cells can be accompanied by induction of p21WAF1/CIP1, but this induction is not necessary for the cell cycle inhibitory effects, nor is it dependent on functional p53. Finally, angiogenesis in astrocytomas has been shown to be dependent on secretion of Vascular Endothelial Growth Factor (VEGF) by tumour cells, particularly under hypoxic conditions. L-744,832 potently inhibits the secretion of VEGF under hypoxic conditions. These combinations of mechanisms suggest that these tumours, despite the absence of oncogenic Ras mutations, will be amenable to growth inhibition by FTIs, through a combination of anti-proliferative, pro-apoptotic, and anti-angiogenic effects.     

A comparative study of balloon mitral valvuloplasty and closed mitral commissurotomy in patients with rheumatic mitral stenosis

Rheumatic mitral stenosis is frequently encountered in our country. It affects younger population and is a major cause of morbidity Mitral valvotomy is the definitive therapy for this disease and can be achieved by closed mitral commissurotomy (CMC), open mitral commissurotomy (OMC) or by percutaneous transluminal mitral valvuloplasty (PTMV). Compared to CMC, PTMV is less invasive but more expensive at this moment. With the reduction of cost, PTMV may become the procedure of choice for the treatment of rheumatic mitral stenosis in future.     

Germline and somatic NF1 gene mutation spectrum in NF1-associated malignant peripheral nerve sheath tumors (MPNSTs)

About 10% of neurofibromatosis type 1 (NF1) patients develop malignant peripheral nerve sheath tumors (MPNSTs) and represent considerable patient morbidity and mortality. Elucidation of the genetic mechanisms by which inherited and acquired NF1 disease gene variants lead to MPNST development is important. A study was undertaken to identify the constitutional and somatic NF1 mutations in 34 MPNSTs from 27 NF1 patients. The NF1 germline mutations identified in 22 lymphocytes DNA from these patients included seven novel mutations and a large 1.4-Mb deletion. The NF1 germline mutation spectrum was similar to that previously identified in adult NF1 patients without MPNST. Somatic NF1 mutations were identified in tumor DNA from 31 out of 34 MPNSTs, of which 28 were large genomic deletions. The high prevalence (>90%) of such deletions in MPNST contrast with the =or<20% found in benign neurofibromas and is indicative of the involvement of different mutational mechanisms in these tumors. Coinactivation of the TP53 gene by deletion, or by point mutation along with NF1 gene inactivation, is known to exacerbate disease symptoms in NF1, therefore TP53 gene inactivation was screened. DNA from 20 tumors showed evidence for loss of heterozygosity (LOH) across the TP53 region in 11 samples, with novel TP53 point mutations in four tumors.     

Preneoplastic markers of hepatitis B virus-associated hepatocellular carcinoma

Hepatitis B virus (HBV) carriers are at high risk for the development of hepatocellular carcinoma (HCC), but there are no reliable markers that will identify such high-risk carriers. The objective of this work is to identify serologic markers that may indicate the early presence of HCC. Since HBV-encoded X antigen (HBxAg) likely contributes to HCC by up- or down-regulation of host gene expression, X positive and negative HepG2 cells were made and subjected to cDNA subtraction. When specific ELISAs were constructed measuring differentially expressed antigens and corresponding antibodies, antibodies to several differentially expressed genes were detected. In cross-sectional and longitudinal studies, antibodies were predominantly present in patients with HBV-associated cirrhosis and HCC, but not in most carriers with hepatic inflammation alone or without active liver disease. Antibodies were also present in patients with hepatitis C virus (HCV)-related HCC, but rarely detected in sera from uninfected individuals, those with tumors other than HCC, or those with drug-induced hepatitis. Statistical analysis showed that HCC patients with four or more antibodies detectable before the appearance of HCC had decreased survival, suggesting that these markers may reflect stepwise hepatocarcinogenesis. Hence, these antibodies may serve as preneoplastic markers for HCC in HBV carriers with chronic liver disease, and may be identified by a simple blood test.     

Determination of Optimum Machining Parameters for Face Milling Process of Ti6A14V Metal Matrix Composite

This paper shows the novel approach of Taguchi-Based Grey Relational Analysis of Ti6Al4V Machining parameter. Ti6Al4V metal matrix composite has been fabricated using the powder metallurgy route. Here, all the components of TI6Al4V machining forces, including longitudinal force (F_x), radial force (F_y), tangential force (F_z), surface roughness and material removal rate (MRR) are measured during the facing operation. The effect of three process parameters, cutting speed, tool feed and cutting depth, is being studied on the matching responses. Orthogonal design of experiment (Taguchi L9) has been adopted to execute the process parameters in each level. To validate the process output parameters, the Grey Relational Analysis (GRA) optimization approach was applied. The percentage contribution of machining parameters to the parameter of response performance was interpreted through variance analysis (ANOVA). Through the GRA process, the emphasis was on the fact that for TI6Al4V metal matrix composite among all machining parameters, tool feed serves as the highest contribution to the output responses accompanied by the cutting depth with the cutting speed in addition. From optimal testing, it is found that for minimization of machining forces, maximization of MRR and minimization of Ra, the best combinations of input parameters are the 2nd stage of cutting speed (175 m/min), the 3rd stage of feed (0.25 mm/edge) as well as the 2nd stage of cutting depth (1.2 mm). It is also found that hardness of Ti6Al4V MMC is 59.4 HRA and composition of that material remain the same after milling operation.     

Arsenicosis and Dietary Nutrient Intake Among Men and Women

To determine the dietary intake of nutrients and its correlation with manifestations of arsenicosis and gender a cross-sectional study was conducted in India among two groups of participants, Group 1 (108 cases having skin lesions) and Group 2 (exposed controls, 100 cases not having skin lesions) with exposure to arsenic drawn from geographical areas known to have high level of arsenic in ground water (above permissible limit, i.e. >50 μg/L). For diet survey, combinations of two methods of diet study i.e. weighment of cooked food and the 24-h diet recall were followed. The nutrients in each food items and calorie consumption were calculated. The mean calorie intake of males was significantly less than that of females in both cases and controls. In both the sexes, mean protein consumption was significantly less than that of the controls. In females, intake of most of the nutrients like thiamin, riboflavin, niacin, magnesium, copper and zinc were less in comparison to controls. In both the sexes mean choline intake was lower significantly in comparison to exposed controls. Riboflavin, copper, zinc and vitamin B₆ consumption were below the RDAs in nearly 90 % of the study population. The strongest trend in ORs was for protein (4.28). The present study revealed that low socio-economic status along with dietary intake of calorie, protein and micronutrients like thiamine, riboflavin, niacin, zinc and choline may have a definite role in increasing the risk of development of arsenicosis.     

Fragmented QRS Complex: A Novel Marker of Cardiovascular Disease

QRS complex fragmentation, defined as changes in QRS morphology with different RSR′ patterns: additional R waves, notched S wave, or > 1R′ wave, has recently been linked with various cardiac conditions and even been postulated to be predictive of outcomes in certain pathologies. The current article aims to consolidate the available information about this morphological ECG abnormality and its predictive value. Copyright © 2010 Wiley Periodicals, Inc.