Vannan K. Vijayan

Critical Care Aspects of Malaria

Malaria remains a major health problem in much of Asia and Africa. A steady number of cases of imported malaria are also seen in many countries of the developed world. Plasmodium falciparum malaria and to some extent malaria caused by other species of Plasmodium can lead to many complications such as acute respiratory distress syndrome (ARDS), cerebral malaria, acute renal failure, severe anemia, thrombocytopenia, and bleeding complications. About 10% of patients with severe malaria die, usually as a result of multiorgan dysfunction. Critical care physicians should be aware of the complications and management of severe malaria. There has been significant progress in the understanding of pathogenesis of severe malaria over the last decade. Effective management of severe malaria includes early suspicion, prompt diagnosis, early institution of appropriate antimalarial chemotherapy, and supportive care, preferably in an intensive care unit. In this article, we review the different manifestations of severe malaria as relevant to critical care physicians and discuss the principles of laboratory diagnosis and management.

Serum interleukin-1β as a marker for differentiation of asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are diseases of airway inflammation with clinical and physiological similarities, making their differentiation difficult. Airway inflammatory changes are associated with systemic changes. However, no serum marker is known for their differentiation. Therefore, serum interleukin (IL)-1β levels were determined. Out of a total of 1023 patients screened, we included in the study ten patients each with atopic asthma, non-atopic asthma and COPD and ten healthy subjects. Skin prick tests with 14 inhalant allergens were performed on each patient. Blood was collected in the symptomatic and asymptomatic phases of the diseases and serum IL-1β and IgE levels were determined. Our results showed that in the symptomatic phase in asthmatics, serum IL-1β levels were higher (P<0.05) than in patients with COPD. Serum IgE levels were higher (P<0.05) in atopic asthmatics than in non-atopic asthmatics and in COPD patients. We conclude that serum IL-1β level determination during the symptomatic phase of the diseases may help to differentiate asthmatics from patients with COPD. Serum IgE levels may differentiate atopic asthmatics from non-atopic asthmatics and COPD patients.

Emerging and established parasitic lung infestations.

Many lung infestations from established and newly emerging parasites have been reported as a result of the emergence of HIV/AIDS, the increasing use of immunosuppressive drugs, increasing organ transplantations, the increase in global travel, and climate change. A renewed interest in parasitic lung infections has been observed recently because many protozoal and helminthic parasites cause clinically significant lung diseases. The diseases caused by these parasites may mimic common and complicated lung diseases ranging from asymptomatic disease to acute respiratory distress syndrome requiring critical care management. The availability of new molecular diagnostic methods and antiparasitic drugs enables early diagnosis and prompt treatment to avoid the morbidity and mortality associated with these infestations. Good hygiene practices, improvement in socioeconomic conditions, vector control measures, and consumption of hygienically prepared and properly cooked food are essential to reduce the occurrence of parasitic infestations.

Systemic Inflammation and Its Response to Treatment in Patients With Asthma

BACKGROUND: Asthma is an obstructive airway disease characterized by airway inflammation. OBJECTIVE: To measure systemic inflammation in asthma patients, and to assess the effect of treatment on systemic inflammation. METHODS: In 30 newly diagnosed non-randomized adult asthma patients we measured systemic inflammation markers (serum high-sensitivity C-reactive protein, total leukocyte count, and erythrocyte sedimentation rate) before and after a 6-week standard treatment with inhaled steroids and inhaled β2 agonist. The comparison group comprised 20 healthy control subjects. All the subjects were non-smokers. RESULTS: The measured systemic inflammation markers were higher in the asthma patients: high-sensitivity C-reactive protein 4.8 ± 6.0 mg/dL vs 1.5 ± 1.4 mg/dL, P < .001; total leukocyte count 8,936 ± 2,592 cells/μL versus 7,741 ± 1,924 cells/μL, P < .001; erythrocyte sedimentation rate 24.8 ± 12.3 mm/h versus 15.3 ± 6.5 mm/h, P < .001. In the asthma patients, high-sensitivity C-reactive protein negatively correlated with percent-of-predicted FEV1 (r = −0.64, P = .001), percent-of-predicted forced vital capacity (FVC) (r = −0.39, P = .03), FEV1/FVC% (r = −0.71, P < .001), and percent-of-predicted forced expiratory flow during the middle half of the FVC maneuver (FEF25-75) (r = −0.51, P = .004). Total leukocyte count negatively correlated with percent-of-predicted FEV1 (r = −0.64, P = .001), percent-of-predicted FEV1/FVC (r = −0.74, P < .001), and percent-of-predicted FEF25-75 (r = −0.58, P = .001). Body mass index positively correlated with high-sensitivity C-reactive protein (r = 0.65, P < .001). Multiple linear regression showed significant correlation of high-sensitivity C-reactive protein (r2 = 0.75) with age (β = 0.31, P = .008), body mass index (β = 0.99, P = .001), family size (β = 0.33, P = .008), and weight (β = –0.45, P = .01). The systemic inflammation markers decreased significantly (P < .001 for all comparisons) after 6 weeks of treatment: high-sensitivity C-reactive protein decreased from 4.8 ± 6.0 mg/dL to 2.4 ± 5.4 mg/dL, total leukocyte count decreased from 8,936 ± 2,592 cells/μL to 6,960 ± 1,785 cells/μL, and erythrocyte sedimentation rate decreased from 24.8 ± 12.3 mm/h to 15.8 ± 10.1 mm/h. CONCLUSIONS: Inhaled steroids plus inhaled β2 agonist significantly reduced systemic inflammation in asthma patients.

Lipids of Erythrocyte Membranes of COPD Patients: A Quantitative and Qualitative Study

Abstract Chronic obstructive pulmonary disease (COPD) is characterized by inflammation of lung parenchyma and pulmonary hypoxemia with a proven systemic component. Tobacco smoke is the most important risk factor and plasma membrane plays a major role in the disease pathology and progression. The properties of biological membranes are a function of their lipid composition. Any change in its composition may lead to the pathophysiology. In COPD research, erythrocytes are emerging as a new therapeutic venture, as their shape and properties change in the disease. Therefore we studied the lipid composition of the erythrocyte membranes of COPD patients. The study included 30 patients having COPD, 10 healthy smokers and 10 non-smokers. Erythrocytes were separated from peripheral blood and their membranes prepared, followed by estimation of proteins, cholesterol and phospholipids. Individual phospholipids were identified and separated by TLC and fatty acid composition determined by gas chromatography. The data were analyzed statistically and P < 0.05 was considered significant. Our results demonstrate that in very severe COPD, proteins decrease, whereas phospholipids and cholesterol contents increase significantly, which showed a consistent negative correlation with FEV1%. The fatty acid analysis showed preponderance towards saturated fatty acids mainly arachidic and behenic acid, suggesting a decrease in membrane fluidity or a closer packing of lipid rafts. We are the first to report about preponderance of saturated fatty acids in plasma membrane of erythrocytes of COPD patients which may decrease the membrane fluidity and possibly impair the functions of the plasma membrane in the disease.

Changes in Protein Profile of Erythrocyte Membrane in Bronchial Asthma

Objectives. Erythrocyte membrane proteins reflect the prototype of multifunctional proteins of various erythroid and non-erythroid cells, which demonstrate various cellular functions. The protein profile of cells changes in various diseases. Therefore, the objective of this study was to understand the changes in protein profile of erythrocyte membranes in bronchial asthma. Methods. The study included 20 patients of bronchial asthma and 20 healthy subjects. Erythrocytes were isolated from peripheral blood, membranes were prepared followed by the determination of protein contents, and protein profile was assessed using SDS-PAGE. Results. In bronchial asthma, the protein contents of erythrocyte membranes in asthmatic patients were significantly higher (p < .005) than in healthy controls. Analysis of protein profile showed absence of the proteins, namely, band 4.2 and adducin subunit-II, and appearance of protein bands of molecular weights corresponding to galectin-3, glyceraldehyde 3-phosphate dehydrogenase, β-actin, dematin, band 4.1, and adducin (subunit-I) in asthmatic patients when compared with healthy controls. Conclusions. In asthma, there are quantitative and qualitative changes in proteins of erythrocyte membranes. The absence of band 4.2 protein may cause impairment of the erythrocyte membrane integrity, and presence of galectin-3 may lead to the activation of various inflammatory cells. The altered protein profile may possibly lead to altered response of the inflammatory cells to the asthmogenic stimuli, which may be responsible for pathophysiology and manifestation of the symptoms of bronchial asthma.

Sphingomyelin metabolism in erythrocyte membrane in asthma

Background. Sphingomyelin (SM), a major lipid constituent of outer leaflet of plasma membranes, with cholesterol, constitutes microdomains, which are termed as lipid rafts. These rafts provide support to proteins, receptors, enzymes, and so on and organize and orient them to conduct cellular functions including transmembrane signaling to substances in external milieu. The SM contents are regulated by its metabolism, changes in which may affect the composition of lipid rafts and cell response to the triggers of asthma which may lead to the pathophysiology. For studying changes in membranes, erythrocytes, which contain lipid rafts, are considered to be the best cell type. Hence, this study was conducted on plasma membrane of erythrocytes of asthmatic patients. Objective. The objective is to understand the changes in SM metabolism in asthma. Methods. The study included 50 subjects (25 asthmatics and 25 healthy subjects). Erythrocytes were isolated from the peripheral blood and membrane prepared. This was followed by determination of total cholesterol, phospholipids, SM, and sphingomyelinase activity. P < .05 was considered significant. Results and conclusions In asthmatics, there was a significant decrease in cholesterol contents (p < .05), decrease in total phospholipid contents (p < .005), increase in SM (p < .01), decrease in cholesterol: SM ratio (p < .001) and increase in sphingomyelinase activity (p < .001) in erythrocyte membranes. We conclude that in asthma, the increase in SM contents is associated with increased sphingomyelinase activity which shows an imbalance in SM metabolism, directed toward its accumulation. The ratio of cholesterol to SM, critical for maintenance of lipid rafts, was significantly lower in asthmatics. This indicates changes in structure of lipid rafts which may lead to the pathophysiology and development of asthma. Regulation of SM metabolism may help in disease regulation and its control.

Calreticulin transacetylase (CRTAase): Identification of novel substrates and CRTAase-mediated modification of protein kinase C (PKC) activity in lymphocytes of asthmatic patients by polyphenolic acetates

Earlier reports from our laboratory established the acetyl transferase function of calreticulin (CRT), enabling CRT to transfer acetyl groups from the acetoxy groups of polyphenolic acetates (PAs) to certain receptor proteins. We have in this paper documented the ability of CRT to catalyze the possible transfer of acetyl moiety from 7-acetamido-4-methylcoumarin (7-N-AMC) to the proteins, glutathione S-transferase (GST), and NADPH cytochrome c reductase, leading to the modification of their catalytic activities. 7-Acetoxy-4-methylthiocoumarin (7-AMTC) compared to 7-acetoxy-4-methylcoumarin (7-AMC) when used as a substrate for calreticulin transacetylase (CRTAase) yielded significantly higher catalytic activity. PM3-optimized geometries suggested that the availability of electrons on the sulfur atom of the thiocarbonyl group of the thiocoumarin may render the substrate binding more favorable to the active site of the enzyme as compared to its oxygen analog. Further CRTAase activity was characterized in the human blood lymphocytes. There was no appreciable difference in CRTAase activity of lymphocytes of asthmatic patients as compared to those of normal subjects. The results presented here highlight for the first time the irreversible inhibition of human blood lymphocytes protein kinase C (PKC) by 7,8-diacetoxy-4-methylcoumarin (DAMC) possibly by way of acetylation. The activity of PKC in lymphocytes of asthmatic patients was found to proportionally increase with the severity of the disease. When PA was incubated with lymphocytes of normal patients, PKC was inhibited marginally. On the other hand, lymphocyte PKC of severe asthmatic patients was inhibited drastically. Several PAs inhibited PKC of asthmatic patients in tune with their specificity to CRTAase. DAMC was found to exert maximum inhibitory action on PKC, while 7,8-dihydroxy-4-methylcoumarin (DHMC), the deacetylated product of DAMC, failed to inhibit PKC. These observations clearly describe DAMC as the novel irreversible inhibitor of PKC, and DAMC may be found useful in the control of inflammation and may serve as a potential drug candidate in the therapy of asthma.

Diagnosis of Pulmonary Parasitic Diseases

The protozoal and helminthic parasites that traverse the respiratory tract during their life cycles can cause lung diseases, though the most common habitats of these parasites are the gastrointestinal tract and the blood or lymphatic circulations. These diseases are commonly encountered in the tropical regions of the world. However, parasitic lung diseases are increasingly being reported from other parts of the world due to an increase in the occurrence of immunosuppression (acquired immunodeficiency syndrome, organ transplantations, the use of immunosuppressive drugs) and transcontinental travel. The lung diseases that may result from these infections range from asymptomatic phase to life-threatening acute respiratory distress syndrome. These diseases can also mimic common respiratory diseases such as bacterial pneumonias, pulmonary tuberculosis, lung cancer, bronchial asthma, interstitial lung disease, and pulmonary hypertension. The diagnosis of parasitic lung diseases is a challenge to physicians, if they are not aware of the entity or these diseases are not investigated properly. The diagnosis of these diseases is based on the identification of the causative organism in the stool, sputum, other body fluids, or tissue specimens. Radiological imaging studies of the thorax including chest radiographs, high-resolution computerized tomograms, and ultrasonograms may aid in the diagnosis. In certain situations, invasive investigations such as fiberoptic bronchoscopic evaluation (transbronchial lung biopsies and bronchoalveolar lavage studies) and thoracic surgical procedures (thoracoscopy and open lung biopsy) may be required for a diagnosis and also to exclude other lung diseases. Serologic and molecular diagnostic methods are being developed for accurate diagnosis of the parasitic diseases.