Chaos in a Tumor Growth Model with Delayed Responses of the Immune System

A simple prey-predator-type model for the growth of tumor with discrete time delay in the immune system is considered. It is assumed that the resting and hunting cells make the immune system. The present model modifies the model of El-Gohary (2008) in that it allows delay effects in the growth process of the hunting cells. Qualitative and numerical analyses for the stability of equilibriums of the model are presented. Length of the time delay that preserves stability is given. It is found that small delays guarantee stability at the equilibrium level (stable focus) but the delays greater than a critical value may produce periodic solutions through Hopf bifurcation and larger delays may even lead to chaotic attractors. Implications of these results are discussed

Chaos in a Tumor Growth Model with Delayed Responses of the Immune System

A simple prey-predator-type model for the growth of tumor with discrete time delay in the immune system is considered. It is assumed that the resting and hunting cells make the immune system. The present model modifies the model of El-Gohary 2008 in that it allows delay effects in the growth process of the hunting cells. Qualitative and numerical analyses for the stability of equilibriums of the model are presented. Length of the time delay that preserves stability is given. It is found that small delays guarantee stability at the equilibrium level stable focus but the delays greater than a critical value may produce periodic solutions through Hopf bifurcation and larger delays may even lead to chaotic attractors. Implications of these results are discussed

Chaos in a Tumor Growth Model with Delayed Responses of the Immune System

A simple prey-predator-type model for the growth of tumor with discrete time delay in the immune system is considered. It is assumed that the resting and hunting cells make the immune system. The present model modifies the model of El-Gohary 2008 in that it allows delay effects in the growth process of the hunting cells. Qualitative and numerical analyses for the stability of equilibriums of the model are presented. Length of the time delay that preserves stability is given. It is found that small delays guarantee stability at the equilibrium level stable focus but the delays greater than a critical value may produce periodic solutions through Hopf bifurcation and larger delays may even lead to chaotic attractors. Implications of these results are discussed

Complex Dynamics in a Mathematical Model of Tumor Growth with Time Delays in the Cell Proliferation

Abstract- In this paper, a simple prey-predator type model for the growth of tumor with discrete time delay in the immune system is considered. It is assumed that the resting and hunting cells make the immune system. The present model allows delay effects in the growth process of the hunting cells. Qualitative and numerical analyses for the stability of equilibriums of the model are presented. Length of the time delay that preserves stability is given. It is found that small delays guarantee stability at the equilibrium level (stable focus) but the delays greater than a critical value may produce periodic solutions through Hopf bifurcation and larger delays may even lead to chaotic attractors. Implications of these results are discussed. Index Terms- tumor growth, prey-predator model, immune system, time delay. I I

Awareness of Biomedical Waste Management in Dental Students in Different Dental Colleges in Nepal

Aim. The aim of this study is to assess the awareness of biomedical waste management in dental students of various dental colleges of Nepal. Methodology. A structured pretested questionnaire was used among 434 (323 males and 111 females) undergraduate dental students of five different dental colleges of Nepal. First part of the questionnaire was used to describe demographic profile of the participants. Second part of the questionnaire assessed the knowledge, attitude, and practice regarding biomedical waste management. Chi-square test was applied to find out the association between different responses obtained from different colleges. Result. Majority (91.82%) of participants had a positive attitude towards safe management of biomedical waste. Regarding the knowledge of BMW management policies, majority of the students (83.1% to 98.9%) had positive attitude towards the safe management of biomedical waste, whereas more than 50% of the students were unaware of the guidelines laid down by Government of Nepal. Regarding biomedical waste disposal technique in the hospital, only 29.9% to 79.8% are aware; this shows that there is lack of strict protocol in the BMW management. Association between different responses and colleges for “improper waste management causes various health hazards” ranged from 93.3% to 98.9%. Conclusion. There exists a lacuna in the knowledge and practice of biomedical waste management among the undergraduate dental students in Nepal. Since the students had positive attitude towards addressing this concern, workshops and trainings related to proper biomedical waste management would be a step forward towards attaining a healthy environment for the future

Hormone receptors over the last 8 years in a cancer referral center in India: What was and what is?

This study was carried out to observe the trend in hormone receptors over the last 8 years in a tertiary cancer center in India. A total of 11,780 tumors analyzed for hormone receptors over the last 7 years were compared with the results of hormone receptor expression in a prior published study on 798 cases of breast cancer from the same institute. The patient′s ages ranged from 18 to 102 years, Sixty percent of the patients were in the age group of 31-50 years. Seventy percent of the tumors were grade III tumors. The percentage of hormone receptor expression in breast cancer in the last 8 years varied from 52 to 57%. The overall receptor expression in the last 8 years shifted within a 5% range, confirming that the hormone receptor expression in Indian patients with breast cancer is low. However, there was redistribution within the pattern of estrogen receptor (ER) and progesterone receptor (PR) expression among tumors showing hormone receptor expression. Breast cancers showing only PR expression reduced dramatically from 21% in the year 1999 to in the year 2006, with a parallel increase in breast cancers showing combined ER and PR positivity (from 25 to 41.8%) and only ER expression (from 7.4 to 10.6%). The hormone receptor expression in breast cancers in India is and continues to be low but the high incidence of only PR-positive tumors in our population reported earlier was misrepresented

Story of survival in anaplastic large cell lymphoma - sometimes more than the anaplastic lymphoma kinase status: An evaluation of pathologic prognostic factors in 102 cases

Introduction: Systemic anaplastic large cell lymphoma (ALCL) accounts for 5%–10% of adult non Hodgkin's lymphoma (NHL) and 10%–30% of childhood NHL. Owing to significant differences in survival and gene expression profile, current WHO classifies ALCL into two distinct entities as anaplastic lymphoma receptor tyrosine kinase (ALK) positive and ALK negative ALCL with ALK expression by tumour as a good prognostic indicator. However, in our institute which is a cancer referral institute, our preliminary experience was that even ALK positive tumours did not fare well as compared to ALK- negative ALCL. So, the current study aims at exploring more clinical and pathological factors impacting survival in ALCL patients. Objective: To study clinical and pathological prognostic factors in cases of ALCL. Methods: 102 cases of ALCL were retrieved from pathology database. Pathological features and clinical features of these cases were recorded and factors found to impact overall survival (OAS) and disease-free survival (DFS) curves were identified based on univariate and multivariate analysis. Results: ALK 1 expression was seen in 71/102 (69.6%) cases and was not found to impact OAS or DFS. The 2 year OAS rate for ALK positive patients was 63.5% and DFS rate was 54.4%, while for ALK negative patients, the OAS was 60.5% and DFS was 43.5%. The Ann Arbor stage, performance status, international prognostic index, histological subtype, and the degree of the background inflammatory infiltrate were found to impact the OAS significantly. Increased reactive inflammatory component also negatively impacted DFS. In the multivariate analysis, only the histologic type emerged as significant for OAS. Conclusion: Though ALK plays a role in prognostication of systemic ALCL, advanced stage disease and an inflammatory milieu may modulate the final outcome. We report a study of clinical and pathologic prognostic features in 102 cases of anaplastic large cell lymphoma (ALCL) from a cancer referral institute in India. Anaplastic lymphoma receptor tyrosine kinase (ALK-1) expression was seen in 71/102 (69.6%) cases and was not found to impact overall survival (OAS) or disease-free survival (DFS). The 2-year OAS rate for ALK-positive patients was 63.5% and DFS rate was 54.4%, while for ALK-negative patients, the OAS was 60.5% and DFS was 43.5%. The Ann Arbor stage, performance status, international prognostic index, histological subtype, and the degree of the background inflammatory infiltrate were found to impact the OAS significantly. Increased reactive inflammatory component also negatively impacted DFS. In the multivariate analysis, only the histologic type emerged as significant for OAS. Thus, though ALK plays a role in prognostication of systemic ALCL, advanced stage disease and an inflammatory milieu may modulate the final outcome

Altered Ocular Surface Health Status and Tear Film Immune Profile Due to Prolonged Daily Mask Wear in Health Care Workers

Prolonged daily face mask wearing over several months might affect health of the ocular surface and is reported to be associated with complaints of discomfort and dry-eye-like symptoms. We studied the ocular surface clinical parameters, tear soluble factors and immune cell proportions in ophthalmologists practicing within similar environmental conditions (n = 17) at two time points: pre-face-mask period (Pre-FM; end of 2019) and post-face-mask-wearing period (Post-FM; during 2020 COVID-19 pandemic), with continuous (~8 h/day) mask wear. A significant increase in ocular surface disease index (OSDI) scores without changes in tear breakup time (TBUT), Schirmer's test 1 (ST1) and objective scatter index (OSI) was observed Post-FM. Tear soluble factors (increased-IL-1β, IL-33, IFNβ, NGF, BDNF, LIF and TSLP; decreased-IL-12, IL-13, HGF and VEGF-A) and mucins (MUC5AC) were significantly altered Post-FM. Ex vivo, human donor and corneoscleral explant cultures under elevated CO2 stress revealed that the molecular profile, particularly mucin expression, was similar to the Post-FM tear molecular profile, suggesting hypercapnia is a potential contributor to ocular surface discomfort. Among the immune cell subsets determined from ocular surface wash samples, significantly higher proportions of leukocytes and natural killer T cells were observed in Post-FM compared to Pre-FM. Therefore, it is important to note that the clinical parameters, tear film quality, tear molecular factors and immune cells profile observed in prolonged mask-wear-associated ocular surface discomfort were distinct from dry eye disease or other common ocular surface conditions. These observations are important for differential diagnosis as well as selection of appropriate ocular surface treatment in such subjects