Missing self by heterogeneous natural killer cells

Some murine (YAC, P815 and SP20) and human (Molt4, Raji and HR7) tumour cell lines were (i) treated with IFN-γ for inducing enhanced expression of MHC class I antigen, or (ii) given a brief treatment with citrate buffer (pH 3.0), which resulted in denaturation of class I MHC antigens on these tumour cells. IFL-γ or acid treated tumour cells were used as unlabelled competing targets in cold target inhibition assays. The results indicated that the competing ability of acid-treated tumour cells remained unaltered, whereas IFN-γ treated tumour cells competed with significantly less efficiency. These results have been evaluated in light of the current view of NK cell development and the expression of inhibitory receptors for MHC class I molecules (IRMs), on NK cells. A modified view on NK cell heterogeneity based upon IRM expression has been proposed which reconciles several apparently discordant observations about the activity and role of NK cells. Two classes of NK cells have been proposed. Type I NK ceils have target recognition receptors which do not recognize autologous normal cells, lack IRMs, and may participate in first line of defence against transformed cells in vivo. Type II NK cells have target recognition receptors for autologous normal cells and express at least one self-reactive IRM in order to prevent auto-killing. Type II NK cells participate in killing those transformed cells which down-regulate their MHC class I expression in order to escape cytotoxic T-cell surveillance. It is also postulated that mechanism of inverse correlation of target cell MHC class I expression levels and their susceptibility to NK cells, involves interference model of missing self hypothesis for type I NK cells and inhibitory signal model of missing self hypothesis for type II NE cells. Finally, it is proposed that acid treatment of tumour cells enhances their lysis susceptibility by making them additionally susceptible to type II NK cells, rather than enhancing their killing by type I NK cells. This proposition would explain the lack of effect of acid treatment on the competing ability of tumour cells, when target cells are only lysed by type I NE cells

Effect of diesel exhaust particulate on bacillus Calmette-Guerin lung infection in mice and attendant changes in lung interstitial lymphoid subpopulations and IFNγ response

The effect of exposure to diesel exhaust particulate (DEP) on bacillus Calmette-Guerin (BCG) lung infection in mice was studied. C57Bl/6J female mice were infected with BCG (2.5×104 bacteria/mouse) by intrapulmonary instillation, with or without coadministration of DEP (100 µ g/mouse). Five weeks later, mice exposed to DEP + BCG had about a four-fold higher BCG load in the lungs than mice exposed only to BCG (p < 0.05). DEP treatment alone had no effect on the total number of lung lymphocytes or numbers of T, B, or NK cells recovered from lungs. In contrast, BCG infection significantly increased (p < 0.05) recovery levels of all types of lymphocytes from lungs. Coexposure to DEP + BCG further increased the recovery of lymphocytes from lungs of BCG-infected mice. The pulmonary lymphocyte subpopulation expressing the greatest levels of mRNA for IFNγ after BCG infection was CD4+ T cells. Expression levels were similar in mice exposed to BCG or BCG + DEP and were elevated as compared to noninfected mice and mice treated with DEP alone. Recovery of IFNγ-secreting lymphocytes and IFNγ-secreting T cells was significantly higher (p < 0.05) from lungs of BCG-infected mice as compared to control or DEP-exposed mice. BCG and BCG+DEP groups of mice did not differ significantly in the numbers of IFNγ-secreting lymphocytes in lungs. Taken together, these results indicated that coexposure to DEP+BCG did not significantly affect the level of IFNγ response of mice to BCG infection. However, DEP treatment was found to inhibit IFNγ-induced nitric oxide (NO) production by mouse alveolar macrophages in vitro. Our results indicate that DEP exposure did not alter the IFNγ response to BCG infection, but reduced responsiveness of alveolar macrophages to IFNγ . Reduced sensitivity of DEP-exposed alveolar macrophages to IFNγ may contribute to a greater load of BCG in the lungs of BCG-infected mice given DEP

High-speed Fabrication of Micro-channels using Line-based Laser Induced Plasma Micromachining (L-LIPMM)

Micro-texturing of surfaces has various applications that often involve texturing over large (macro-scale) areas with high precision and resolution. This demands scalability and speed of texturing while retaining feature sizes on the order of a few ?m. Moreover, micro-channels are a versatile micro-feature that are often used in microfluidic devices and can be arrayed or joined to form patterns and free-form geometries. We present a technique to fabricate micro-channels on surfaces with high-speed and by using a multi-materials process, namely Laser Induced Plasma Micromachining (LIPMM). The process has the potential to machine metals, ceramics, polymers and other transparent, brittle and hard-to-machine materials. The presented technique uses an optical system to modify the laser spot into the shape of a line, to fabricate micro-channels directly without scanning as in the case of a regular circular spot. The process schematics are shown, and micro-machining experiments on polished Aluminum are discussed. Moreover, it is shown that the depth and width of the channels may be varied by changing the process parameters like the pulse energy, pulse frequency and number of exposures

Performance Analysis of MIMO-STBC Systems with Higher Coding Rate Using Adaptive Semiblind Channel Estimation Scheme

Semiblind channel estimation method provides the best trade-off in terms of bandwidth overhead, computational complexity and latency. The result after using multiple input multiple output (MIMO) systems shows higher data rate and longer transmit range without any requirement for additional bandwidth or transmit power. This paper presents the detailed analysis of diversity coding techniques using MIMO antenna systems. Different space time block codes (STBCs) schemes have been explored and analyzed with the proposed higher code rate. STBCs with higher code rates have been simulated for different modulation schemes using MATLAB environment and the simulated results have been compared in the semiblind environment which shows the improvement even in highly correlated antenna arrays and is found very close to the condition when channel state information (CSI) is known to the channel

Natural Killer Cells Interaction with Carbon Nanoparticles

The increased use of nanomaterials for biomedical purposes has warranted the need to introspect their toxicological properties and assess their utility to human health, particularly the immune system. Natural killer (NK) cells hold a pivotal position in innate immunity and serve as first line of defense against foreign bodies. Acid functionalized Carbon nanotubes (CNTs) that easily polydisperse in aqueous solution and could be coupled with fluorescent molecules were used to study the effect of carbon nanoparticles on NK cells in vitro and in vivo. Flow cytometry-based assays were used to study the effect of CNTs on various physiological parameters of NK cells, such as cell recovery, apoptosis, cell cycle, and generation of reactive oxygen species. A downregulation of the cytotoxicity of IL-2-activated murine NK cells was observed in the presence of acid-functionalized CNTs. The mechanistic basis of this downregulation was studied by assessing markers of NK cell activation (CD69), generation (NLK1.1), degranulation (CD107a) and apoptosis (annexin V assay). This chapter provides a blueprint for assessing the effect of carbon nanoparticles on NK cells. The assays mentioned in this chapter can be extrapolated to study the effect of other nanoparticles on different cell types as well

A Double In Vivo Biotinylation Technique to Assess Erythrocyte Turnover in Blood Circulation

We have developed a new double in vivo biotinylation (DIB) technique that may be used for assessing turnover patterns of erythrocytes in circulation. This technique involves two successive in vivo biotinylation steps, interspersed by a period of 5–30 days, which would enable us to tag with biotin a population of erythrocytes entering blood circulation over a defined period of time, between the two biotinylation steps. As such we can track the age-related changes in a lifetime of the circulating erythrocytes, or we can simultaneously study two defined age cohorts of aged as well as young erythrocytes in circulation. We have extensively used this technique to look at erythrocyte loss in mouse models of anemia induced by (a) heavy metal cadmium (Cd), (b) herbicide Paraquat (PQ), (c) carbon nanotubes (CNTs), and (d) autoantibody in autoimmune hemolytic anemia (AIHA). We have found that the pattern of erythrocyte removal is distinctly different in different models of murine anemia. In certain types of anemia (CNT and AIHA), younger erythrocytes in blood circulation are preferentially removed, whereas in other cases (Cd and PQ), old erythrocytes are specifically eliminated

Audit of caesarian deliveries in a tertiary care center, in rural Bangalore, India

Background: The Robson’s Ten-Group Classification System allows critical analysis of caesarean deliveries according to characteristics of pregnancy. The objective was to analyze caesarean section rates in a rural tertiary care teaching hospital in Bangalore, using Robson’s ten groups classification.Methods: This study was done in MVJ Medical College and Research Hospital, a rural tertiary care teaching hospital. All patients who underwent caesarean delivery, between November 2017 and October 2018, were included in the study. Women were classified in 10 groups according to Robson’s classification. For each group, authors calculated its relative contribution to the overall caesarean rate.Results: The overall caesarean section rate was 46.7%. The main contributors to this high caesarean rate were primiparous women in spontaneous labour (group 1) and women with previous caesarean section (group 5).  52.1% of CS were conducted on women who were unbooked or booked at a peripheral health facility and referred to present institution due to complications in labor. Strategies to lower CS rates would include encouraging women with previous CS, to undergo trial of labor to reduce CS rates for group 5C. Sensitization of staff in peripheral medical facilities for early referral of high-risk pregnancies to a tertiary care center for better control of medical complications like hypertensive disorders of diabetes mellitus. Other strategies include offering external cephalic version to eligible women with breech presentation and consider offering vaginal breech delivery to suitable women in groups 6 and 7.Conclusions: The Robson’s classification is easy to use. It is time to implement obstetric audit to lower the overall CS rates

Age-dependent increase in green autofluorescence of blood erythrocytes

Green auto-fluorescence (GAF) of different age groups of mouse blood erythrocytes was determined by using a double in vivo biotinylation (DIB) technique that enables delineation of circulating erythrocytes of different age groups. A significant increase in GAF was seen for erythrocytes of old age group (age in circulation >40 days) as compared to young erythrocytes (age <15 days). Erythrocytes are removed from blood circulation by macrophages in the reticulo-endothelial system and depletion of macrophages results in an increased proportion of aged erythrocytes in the blood. When mice were depleted of macrophages for 7 days by administration of clodronate loaded liposomes, the overall GAF of erythrocytes increased significantly and this increase could be ascribed to an increase in GAF of the oldest population of erythrocytes. Using the DIB technique, the GAF of a cohort of blood erythrocyte generated during a 5 day window was tracked in vivo. GAF of the defined cohort of erythrocytes remained low till 40 days of age in circulation and then increased steeply till the end of the life span of erythrocytes. Taken together our results provide evidence for an age dependent increase in the GAF of blood erythrocytes that is accentuated by depletion of macrophages. Kinetics of changes in GAF of circulating erythrocytes with age has also been defined

Effectiveness of diabetes in pregnancy study group India diagnostic criterion in detecting gestational diabetes mellitus: a rural Bangalore study

Background: The oral glucose tolerance test (OGTT) is considered the current standard for diagnosis of gestational diabetes mellitus (GDM). International association of diabetes and pregnancy study groups (IADPSG) recommends OGTT, with fasting, one-hour and two-hour venous blood samples drawn after intake of 75g oral glucose. In the Indian context, diabetes in pregnancy study group in India (DIPSI) recommends glucose challenge test (GCT), where 75 g glucose is given irrespective of the fasting state, and a single venous sample is drawn after two-hour. Diagnosis of GDM is made, if any cut-off value is met or exceeded. This prospective study was conducted to compare the DIPSI and IADPSG criteria for diagnosis of GDM.Methods: Pregnant women between 24 to 28 weeks of gestation were subjected to non-fasting GCT. Capillary sample were also drawn simultaneously using Accu check active glucometer. These women were counselled to undergo a standard 75gram OGTT, within a week of recruitment.Results: According to IADPSG criteria, 17.6% (18/102) of our participants had GDM, as compared to 19.6% (20/102) by DIPSI criteria using venous samples, and 25.3% (25/99) by capillary sample method. Sensitivity and specificity of GCT using venous sample was 72.22% and 91.67%, and using capillary sample was 70.59% and 84.15% respectively. DIPSI criteria using venous samples wrongly labelled 8.3% women as GDM, and capillary samples wrongly labelled 15.9% women as GDM. More importantly DIPSI criteria using venous samples labelled 27.8% women as false-negative and capillary samples labelled 29.4% women as false-negative for GDM. Almost one quarter of women with GDM will be missed if DIPSI criteria is used as a universal screening modality.Conclusions: We suggest that the IADPSG criteria be used for diagnosis of GDM in antenatal women in India