Characterization of the major surface glycoconjugates of Trypanosoma theileri

Trypanosoma theileri maintains a long-term extracellular infection with a low parasitaemia in bovids. The surface of this parasite is predicted to be decorated with several surface molecules including membrane surface proteases (MSPs), trans-sialidases and T. theileri putative surface proteins (TTPSPs). However, there are no experimental data to verify this hypothesis. Here, we have purified and partially characterized the surface glycoconjugates of T. theileri using biochemical and mass spectrometry-based approaches. The glycoconjugates fall into two classes: glycoproteins and glycolipids. Proteomic analysis of the glycoprotein fraction demonstrated the presence of MSPs and abundant mucin-like TTPSPs, with most predicted to be GPI-anchored. Mass spectrometric characterization of the glycolipid fraction showed that these are mannose- and galactose-containing glycoinositolphospholipids (GIPLs) that are larger and more diverse than those of its phylogenetic relative T. cruzi, containing up to 10 hexose residues and carrying either alkylacyl-phosphatidylinositol or inositol-phospho-ceramide (IPC) lipid components.

Defining early steps in Bacillus subtilis biofilm biosynthesis

IMPORTANCE

Biofilms are the communal way of life that microbes adopt to increase survival. Key to our ability to systematically promote or ablate biofilm formation is a detailed understanding of the biofilm matrix macromolecules. Here, we identify the first two essential steps in the Bacillus subtilis biofilm matrix exopolysaccharide (EPS) synthesis pathway. Together, our studies and approaches provide the foundation for the sequential characterization of the steps in EPS biosynthesis, using prior steps to enable chemoenzymatic synthesis of the undecaprenyl diphosphate-linked glycan substrates.

Identification of the glycosylphosphatidylinositol-specific phospholipase A2 (GPI-PLA2) that mediates GPI fatty acid remodeling in Trypanosoma brucei

The biosynthesis of glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) in the parasitic protozoan Trypanosoma brucei involves fatty acid remodeling of the GPI precursor molecules before they are transferred to protein in the endoplasmic reticulum. The genes encoding the requisite phospholipase A2 and A1 activities for this remodeling have thus far been elusive. Here, we identify a gene, Tb927.7.6110, that encodes a protein that is both necessary and sufficient for GPI-phospholipase A2 (GPI-PLA2) activity in the procyclic form of the parasite. The predicted protein product belongs to the alkaline ceramidase, PAQR receptor, Per1, SID-1, and TMEM8 (CREST) superfamily of transmembrane hydrolase proteins and shows sequence similarity to Post-GPI-Attachment to Protein 6 (PGAP6), a GPI-PLA2 that acts after transfer of GPI precursors to protein in mammalian cells. We show the trypanosome Tb927.7.6110 GPI-PLA2 gene resides in a locus with two closely related genes Tb927.7.6150 and Tb927.7.6170, one of which (Tb927.7.6150) most likely encodes a catalytically inactive protein. The absence of GPI-PLA2 in the null mutant procyclic cells not only affected fatty acid remodeling but also reduced GPI anchor sidechain size on mature GPI-anchored procyclin glycoproteins. This reduction in GPI anchor sidechain size was reversed upon the re-addition of Tb927.7.6110 and of Tb927.7.6170, despite the latter not encoding GPI precursor GPI-PLA2 activity. Taken together, we conclude that Tb927.7.6110 encodes the GPI-PLA2 of GPI precursor fatty acid remodeling and that more work is required to assess the roles and essentiality of Tb927.7.6170 and the presumably enzymatically inactive Tb927.7.6150.

Defining Early Steps in B. subtilis Biofilm Biosynthesis

The Bacillus subtilis extracellular biofilm matrix includes an exopolysaccharide that is critical for the architecture and function of the community. To date, our understanding of the biosynthetic machinery and the molecular composition of the exopolysaccharide of B. subtilis remains unclear and incomplete. This report presents synergistic biochemical and genetic studies built from a foundation of comparative sequence analyses targeted at elucidating the activities of the first two membrane-committed steps in the exopolysaccharide biosynthetic pathway. By taking this approach, we determined the nucleotide sugar donor and lipid-linked acceptor substrates for the first two enzymes in the B. subtilis biofilm exopolysaccharide biosynthetic pathway. EpsL catalyzes the first phosphoglycosyl transferase step using UDP-di- N -acetyl bacillosamine as phospho-sugar donor. EpsD is a GT-B fold glycosyl transferase that facilitates the second step in the pathway that utilizes the product of EpsL as an acceptor substrate and UDP- N -acetyl glucosamine as the sugar donor. Thus, the study defines the first two monosaccharides at the reducing end of the growing exopolysaccharide unit. In doing so we provide the first evidence of the presence of bacillosamine in an exopolysaccharide synthesized by a Gram-positive bacterium.

IMPORTANCE

Biofilms are the communal way of life that microbes adopt to increase survival. Key to our ability to systematically promote or ablate biofilm formation is a detailed understanding of the biofilm matrix macromolecules. Here we identify the first two essential steps in the Bacillus subtilis biofilm matrix exopolysaccharide synthesis pathway. Together our studies and approaches provide the foundation for the sequential characterization of the steps in exopolysaccharide biosynthesis, using prior steps to enable chemoenzymatic synthesis of the undecaprenol diphosphate-linked glycan substrates.

A Trypanosoma brucei β3 glycosyltransferase superfamily gene encodes a β1-6 GlcNAc-transferase mediating N-glycan and GPI anchor modification

The parasite Trypanosoma brucei exists in both a bloodstream form (BSF) and a procyclic form (PCF), which exhibit large carbohydrate extensions on the N-linked glycans and glycosylphosphatidylinositol (GPI) anchors, respectively. The parasite's glycoconjugate repertoire suggests at least 38 glycosyltransferase (GT) activities, 16 of which are currently uncharacterized. Here, we probe the function(s) of the uncharacterized GT67 glycosyltransferase family and a β3 glycosyltransferase (β3GT) superfamily gene, TbGT10. A BSF-null mutant, created by applying the diCre/loxP method in T. brucei for the first time, showed a fitness cost but was viable in vitro and in vivo and could differentiate into the PCF, demonstrating nonessentiality of TbGT10. The absence of TbGT10 impaired the elaboration of N-glycans and GPI anchor side chains in BSF and PCF parasites, respectively. Glycosylation defects included reduced BSF glycoprotein binding to the lectin ricin and monoclonal antibodies mAb139 and mAbCB1. The latter bind a carbohydrate epitope present on lysosomal glycoprotein p67 that we show here consists of (-6Galβ1-4GlcNAcβ1-)≥4 poly-N-acetyllactosamine repeats. Methylation linkage analysis of Pronase-digested glycopeptides isolated from BSF wild-type and TbGT10 null parasites showed a reduction in 6-O-substituted- and 3,6-di-O-substituted-Gal residues. These data define TbGT10 as a UDP-GlcNAc:βGal β1-6 GlcNAc-transferase. The dual role of TbGT10 in BSF N-glycan and PCF GPI-glycan elaboration is notable, and the β1-6 specificity of a β3GT superfamily gene product is unprecedented. The similar activities of trypanosome TbGT10 and higher-eukaryote I-branching enzyme (EC 2.4.1.150), which belong to glycosyltransferase families GT67 and GT14, respectively, in elaborating N-linked glycans, are a novel example of convergent evolution.

Elimination of GPI2 suppresses glycosylphosphatidylinositol GlcNAc transferase activity and alters GPI glycan modification in Trypanosoma brucei

Many eukaryotic cell-surface proteins are post-translationally modified by a glycosylphosphatidylinositol (GPI) moiety that anchors them to the cell membrane. The biosynthesis of GPI anchors is initiated in the endoplasmic reticulum by transfer of GlcNAc from UDP-GlcNAc to phosphatidylinositol. This reaction is catalyzed by GPI GlcNAc transferase, a multisubunit complex comprising the catalytic subunit Gpi3/PIG-A as well as at least five other subunits, including the hydrophobic protein Gpi2, which is essential for the activity of the complex in yeast and mammals, but the function of which is not known. To investigate the role of Gpi2, we exploited Trypanosoma brucei (Tb), an early diverging eukaryote and important model organism that initially provided the first insights into GPI structure and biosynthesis. We generated insect-stage (procyclic) trypanosomes that lack TbGPI2 and found that in TbGPI2-null parasites, (i) GPI GlcNAc transferase activity is reduced, but not lost, in contrast with yeast and human cells, (ii) the GPI GlcNAc transferase complex persists, but its architecture is affected, with loss of at least the TbGPI1 subunit, and (iii) the GPI anchors of procyclins, the major surface proteins, are underglycosylated when compared with their WT counterparts, indicating the importance of TbGPI2 for reactions that occur in the Golgi apparatus. Immunofluorescence microscopy localized TbGPI2 not only to the endoplasmic reticulum but also to the Golgi apparatus, suggesting that in addition to its expected function as a subunit of the GPI GlcNAc transferase complex, TbGPI2 may have an enigmatic noncanonical role in Golgi-localized GPI anchor modification in trypanosomes.

ProGlycProt V2.0, a repository of experimentally validated glycoproteins and protein glycosyltransferases of prokaryotes

Knowledge of glycosylation status and glycan-pattern of proteins are of considerable medical, academic and application interest. ProGlycProt V2.0 (www.proglycprot.org) therefore, is conceived and maintained as an exclusive web-resource providing comprehensive information on experimentally validated glycoproteins and protein glycosyltransferases (GTs) of prokaryotic origin. The second release of ProGlycProt features a major update with a 191% increase in the total number of entries, manually collected and curated from 607 peer-reviewed publications, on the subject. Protein GTs from prokaryotes that catalyze a varied range of glycan linkages are amenable glycoengineering tools. Therefore, the second release presents content that is greatly expanded and reorganized in two sub-databases: ProGPdb and ProGTdb. While ProGPdb provides information about validated glycoproteins (222 entries), ProGTdb catalogs enzymes/proteins that are instrumental in protein glycosylation, directly (122) or as accessory proteins (182). ProGlycProt V2.0 remains highly cross-referenced yet exclusive and complementary in content to other related databases. The second release further features enhanced search capability, a "compare" entries option and an innovative geoanalytical tool (MapView) facilitating location-assisted search-cum filtering of the entries using geo-positioning information of researchers/groups cited in the ProGlycProt V2.0 databases. Thus, ProGlycProt V2.0 continues to serve as a useful one-point web-resource on various evidence-based information on protein glycosylation in prokaryotes.

In Vitro Synthesis of Bioactive Glycovariants of Enterocin 96, an Antimicrobial Peptide from Enterococcus faecalis

Antimicrobial peptides (AMPs) are novel agents for therapeutic application for their inherent broad spectrum of activities against bacteria, fungi, and viruses, as well as anti-inflammatory, anticancerous, and immunomodulatory activities. This chapter presents an enzymatic method to generate glycovariants of one such antimicrobial peptide, namely enterocin 96, using a bacterial protein O- and S-glycosyltransferase, in vitro.

Gluconeogenesis using glycerol as a substrate in bloodstream-form Trypanosoma brucei

Bloodstream form African trypanosomes are thought to rely exclusively upon glycolysis, using glucose as a substrate, for ATP production. Indeed, the pathway has long been considered a potential therapeutic target to tackle the devastating and neglected tropical diseases caused by these parasites. However, plasma membrane glucose and glycerol transporters are both expressed by trypanosomes and these parasites can infiltrate tissues that contain glycerol. Here, we show that bloodstream form trypanosomes can use glycerol for gluconeogenesis and for ATP production, particularly when deprived of glucose following hexose transporter depletion. We demonstrate that Trypanosoma brucei hexose transporters 1 and 2 (THT1 and THT2) are localized to the plasma membrane and that knockdown of THT1 expression leads to a growth defect that is more severe when THT2 is also knocked down. These data are consistent with THT1 and THT2 being the primary routes of glucose supply for the production of ATP by glycolysis. However, supplementation of the growth medium with glycerol substantially rescued the growth defect caused by THT1 and THT2 knockdown. Metabolomic analyses with heavy-isotope labelled glycerol demonstrated that trypanosomes take up glycerol and use it to synthesize intermediates of gluconeogenesis, including fructose 1,6-bisphosphate and hexose 6-phosphates, which feed the pentose phosphate pathway and variant surface glycoprotein biosynthesis. We used Cas9-mediated gene knockout to demonstrate a gluconeogenesis-specific, but fructose-1,6-bisphosphatase (Tb927.9.8720)-independent activity, converting fructose 1,6-bisphosphate into fructose 6-phosphate. In addition, we observed increased flux through the tricarboxylic acid cycle and the succinate shunt. Thus, contrary to prior thinking, gluconeogenesis can operate in bloodstream form T. brucei. This pathway, using glycerol as a physiological substrate, may be required in mammalian host tissues.

An iterative glycosyltransferase EntS catalyzes transfer and extension of O- and S-linked monosaccharide in enterocin 96

Glycosyltransferases are essential tools for in vitro glycoengineering. Bacteria harbor an unexplored variety of protein glycosyltransferases. Here, we describe a peptide glycosyltransferase (EntS) encoded by ORF0417 of Enterococcus faecalis TX0104. EntS di-glycosylates linear peptide of enterocin 96 - a known antibacterial, in vitro. It is capable of transferring as well as extending the glycan onto the peptide in an iterative sequential dissociative manner. It can catalyze multiple linkages: Glc/Gal(-O)Ser/Thr, Glc/Gal(-S)Cys and Glc/Gal(β)Glc/Gal(-O/S)Ser/Thr/Cys, in one pot. Using EntS generated glycovariants of enterocin 96 peptide, size and identity of the glycan are found to influence bioactivity of the peptide. The study identifies EntS as an enzyme worth pursuing, for in vitro peptide glycoengineering.

Numerical Simulation and Experimental Validation of Granite Powder Filled Jute Epoxy Composite for Slurry Jet Erosive Wear

In the polymer composite the benefits of utilizing the excellent wear resisting properties in terms of light weight structural design are immediately apparent. Hence, the focus of this study is to propose new sets of unfilled and particulate filled treated jute epoxy composites. Therefore, initially five different weight percentages of alkali treated jute epoxy composites are fabricated (10, 20, 30 40 and 50 wt.%) and studied their slurry erosive wear in experimentally at different operating conditions such as by varying impact velocity and impingement angle by keeping all other factors constant. The steady state erosion results for jute epoxy composites shows better wear resistant behavior for 40 wt.% jute fiber loading. Hence, for further fabrication of series of hybrid composite 40 wt.% jute fiber is kept constant and granite powder is varied in three different (8, 16 and 24 wt.%) weight percentages. The granite filler content in the jute epoxy composite played a major contribution for slurry erosion resistance. Finally, the obtained experimental results are compared with simulated model results by using a computational fluid dynamics tool. The eroded samples are observed through scanning electron microscope to study the wear mechanism.

Standardized modulation of the injection site allows for insulin dose reduction without deterioration of metabolic control

OBJECTIVES

Use of an injection site modulation device (InsuPad) in intensive insulin treatment reduces frequency of hypoglycemia and prandial insulin requirements by enhancing subcutaneous microcirculation. This meal tolerance test (MTT) investigation was performed as a sub-study during the real-world BARMER study to demonstrate non-inferiority of the reduced insulin doses observed in this study with respect to metabolic control.

METHODS

The MTT was performed at baseline and after 3 months in insulin treated diabetes patients using the modulation device vs. a control group without device. The dose used for the MTT was individually calculated based on the prandial insulin records from the patient diaries before the test. Blood was drawn for determination of glucose, insulin, C-peptide, proinsulin, triglycerides, free fatty acids, nitrotyrosine, and asymmetric dimethyl-arginine (ADMA) at multiple time-points from 0 to 300 min. A total of 32 patients from one site were included into this MTT study (8 female, 7 type 1 diabetes, age: 49.9 ± 12.5 yrs, HbA1c: 7.2 ± 0.5%).

RESULTS

During the BARMER study, mean HbA1c was treated to target (<6.5%) in both groups. The prandial insulin dose decreased in the MTT modulation device group by -17.1%, but remained unchanged in the control group (-0.1%, p < 0.001). No change was seen for the basal insulin dose in both treatment arms. There were no differences between the groups with respect to the postprandial curves for glucose, C-peptide, intact proinsulin, free fatty acids, and triglycerides. Insulin absorption was faster with the modulation device (Tmax: 60 ± 28 min vs. 99 ± 46 min, p < 0.05). Key limitations are the small patient sample size and impossibility to determine the short-term effects of device use.

CONCLUSIONS

The results of this meal tolerance sub-study confirm that the observed prandial insulin dose reduction when using the injection site modulation device has no negative impact on postprandial metabolism.

The Barmer study: impact of standardized warming of the injection site to enhance insulin absorption and reduce prandial insulin requirements and hypoglycemia in obese patients with diabetes mellitus

BACKGROUND

The primary objective of this prospective controlled study was to investigate the impact of standardized injection-site warming on prandial rapid acting insulin dose and glycemic control when studied under real-world conditions.

METHODS

All 145 participating patients (51 female, 94 male, 13 type 1 and 132 type 2 patients, age: 61.6 ± 8.4 yrs, HbA1c: 7.19 ± 0.50%) were treated with intensive insulin glargine and short-acting insulin analog therapy. After a 4 week treatment optimization run-in period, patients were randomized to continue therapy for three months without (control) or with a local injection-site warming device (InsuPad * ). Observation parameters included HbA1c, insulin dose, frequency of hypoglycemia, body weight and adverse events.

RESULTS

HbA1c improved in both arms until study end (control group: 6.3 ± 0.5%; injection-site warming device: 6.3 ± 0.5%; both p < 0.001 vs. baseline). To achieve this good control, patients in the control group needed to increase the daily prandial insulin dose by 8.1% (from 66 ± 31 U to 71 ± 38 U, p < 0.05) with stable basal insulin requirements. Patients who used the injection-site warming device required less prandial insulin (70 ± 43 U to 55 ± 34 U; -19%, p < 0.001) and slightly more basal insulin (+3.9%). Total daily insulin dose increased in the control group (+3.7%) and decreased with warming device use (-8.6%, p < 0.001). The number of hypoglycemic events (<63 mg/dL) during the observation period was higher in the control group (6.2 ± 9.9/patient vs. injection-site warming device: 3.3 ± 4.8/patient, p < 0.05). Main study limitations can be seen in the open label design reliability of the collected dose information and the very obese patient cohort.

CONCLUSION

When treating obese patients to target with insulin therapy, use of an injection-site warming device for 3 months resulted in a lower frequency of hypoglycemic events and a reduction in prandial insulin analog requirements. If these results are confirmed in other patient populations, an injection-site warming device may be useful in achieving treatment targets with a safer and more efficient basal bolus therapy in insulin-treated patients with type 1 and type 2 diabetes.

Effect of cooking, fermentation, dehulling and utensils on antioxidants present in pearl millet rabadi - a traditional fermented food

Effect of cooking, fermentation, dehulling and the use of utensils on flavonoids (quercitin and pelargonidin) - antioxidants present in pearl millet (Pennisetum typhoideum) rabadi, along with proximate composition and sensory acceptability of the product were studied. Study revealed an increased ash and flavonoids and reduced crude fibre after cooking in all samples, while fermentation enhanced the crude protein and reduced fat and crude fibre after 16 h in fermented-cooked-fermented rabadi prepared in steel and earthen pot and cooked-fermented rabadi in earthen pot. Enhanced flavonoids were observed in all samples after 16 h fermentation. Fermented-cooked-fermented samples were better with high (ρ<0.05) protein in steel pot rabadi and high (ρ<0.001) ash and quercitin (ρ<0.1 in earthen pot rabadi. Major nutrients were unaffected after dehulling except the crude fibre, which decreased and quercitin increased significantly (ρ<0.1). Remarkable rise in quercitin was observed when rabadi was fermented-cooked and fermented in earthen pot. Sensory evaluation showed the acceptance of all samples in the range of liked extremely (fermented-cooked-fermented-steel pot) to liked slightly (fermented-cooked in earthen pot).

Effect of pretreatment with chromium picolinate on haematological parameters during dengue virus infection in mice

BACKGROUND & OBJECTIVE

Dengue virus (DV) has caused severe epidemics of dengue fever (DF) and dengue haemorrhagic fever (DHF) and is endemic all over India. We have earlier reported that exposure of mice to hexavalent chromium [Cr(VI)] compounds increased the severity of dengue virus infection. Trivalent chromium picolinate (CrP) is used worldwide as micronutrient and nutritional supplement. The present study was therefore, carried out to investigate the effects of CrP on various haematological parameters during DV infection of mice.

METHODS

The Swiss Albino smice were inoculated with dengue virus (1000 LD50, intracerebrally) and fed with chromium picolinate (CrP) in drinking water (100 and 250 mg/l) for 24 wk. Peripheral blood leucocytes and other haematological parameters, and spleens were studied on days 4 and 8 after virus inoculations and the findings were compared with those given only CrP and the normal control age matched mice.

RESULTS

CrP in drinking water for 24 wk had no significant effects on peripheral blood cells of mice. On the other hand, there was significant decrease in different haematological parameters following inoculation of normal mice with DV. In CrP fed mice the effects of DV infection were abolished on most of the haematological parameters.

INTERPRETATION & CONCLUSION

The findings of present study showed that the adverse effects of DV infection, specially on platelets and leucocytes, were abrogated by pretreatment of mice with CrP. The therapeutic utility of CrP in viral infections including dengue needs to be studied in depth.

Levels of beta-carotene and effects of processing on selected fruits and vegetables of the arid zone of India

Some locally available fruits and vegetables of the arid zone of Rajasthan were analyzed for their beta-carotene content; the selected fruits and vegetables were: Dansra (Rhus myserensis), Kachri (Cucumis collosus), fruit Kachri (Cucumis collosus), Kair (Capparis decidua) and Sanghri (Prosopis cineriria). The beta-carotene contents of the samples were estimated in fresh and various processed states (blanched, dried and roasted). The results showed the heat lability of beta-carotene. Among the samples, kair was found to be the richest source of beta-carotene. Variety, too, had an impact on the content of this fat soluble vitamin.

Lipoprotein(a) in coronary heart disease: a case-control study

To determine the significance of lipoprotein(a) levels in coronary heart disease patients, a case-control study was performed with 48 newly diagnosed coronary heart disease patients and 23 controls who were evaluated using clinical history and biochemical examination. Lipoprotein(a) was measured by quantitative latex-enhanced immunoturbidimetric method. Geometric means of biochemical parameters were obtained. Comprehensive lipid tetrad index was calculated using a previously validated formula. There was no significant difference in prevalence of diabetes, hypertension and smoking in cases and controls. Dietary intake of calories, fats, fatty acids and antioxidant vitamins was also similar. The levels of fasting glucose, cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides were not significantly different in cases and controls (p > 0.05). Low-density lipoprotein/high-density lipoprotein ratio (4.33 +/- 1.5 vs 4.29 +/- 1.8) and total cholesterol/high-density lipoprotein ratio (6.59 + 1.7 vs 6.69 +/- 2.2) were similar. The mean lipoprotein(a) levels were significantly greater in cases (11.95 +/- 2.8 mg/dL, range 1-102 mg/dL) as compared to controls (6.68 +/- 3.4 mg/dL, range 1-73 mg/dL) (t = 2.08, p = 0.041). As compared to controls, in coronary heart disease cases, mean lipoprotein(a) levels in patients upto 50 years (10.27 +/- 2.8 vs 7.27 +/- 3.4 mg/dL) as well as those over 50 years (12.99 +/- 2.9 vs 4.91 +/- 3.5 mg/dL) were significantly more (p < 0.05). Coronary heart disease patients had a slightly greater prevalence of high lipoprotein(a) levels, 20 mg/dL or more (31.3 vs 13.0%; chi 2 = 2.83, l-tailed p < 0.05). Comprehensive lipid tetrad index (total cholesterol x triglycerides x lipoprotein(a) divided by high-density lipoprotein cholesterol) was also slightly higher in cases (14688.2 +/- 3.6) than in controls (8358.2 +/- 4.3) (t = 1.68, 1-tailed p < 0.05). This study shows that lipoprotein(a) levels are significantly more in both younger and older coronary heart disease patients as compared to controls.

Role of interleukin-12 in patients with dengue hemorrhagic fever

Interleukin (IL)-12 has a broad range of activities including regulation of cytokine synthesis and selective promotion of Th1-type cell development. A shift from a Th1-type response to Th2-type has been suggested to be important in the pathogenesis of dengue hemorrhagic fever (DHF). This study was undertaken to investigate the possible role of IL-12 in this shift. A total of 76 patients with various grades of dengue illness and 21 normal healthy controls were tested for IL-12 levels in serum samples and IL-12 mRNA in their peripheral blood mononuclear cells. The results showed that the levels of IL-12 were the highest in patients with dengue fever (270+/-102 pg ml(-1)) followed by decreasing levels in the patients with DHF grade I (198+/-86 pg ml(-1); P<0.05) and DHF grade II (84+/-52 pg ml(-1); P<0.001). Neither IL-12 nor its mRNA could be detected in the patients with DHF grades III and IV. The cytokine appeared and reached peak levels during the first 4 days of illness, started to decline by day 5-8 and disappeared by day 9 onwards. The absence of IL-12 during severe illness and late phases of the disease may be responsible for the shift to a Th2-type response and thus for the pathogenesis of DHF.

Dietary and serum iron, body iron stores and coronary heart disease

OBJECTIVES

To determine the role of body-iron stores as measured by serum iron, total iron binding capacity (TIBC), transferrin, ferritin and ferritin:transferrin ratio (FTR) in patients with coronary heart disease (CHD).

METHODS

A case-control study was performed in 58 newly diagnosed CHD patients and 24 controls who were evaluated using clinical history, dietary history and biochemical examination. Dietary iron was determined by history; serum iron and TIBC were measured biochemically and ferritin by enzyme-linked immunoassay. Case-control comparisons were performed by non-parametric Mann-Whitney test.

RESULTS

There was no significant difference in mean age, prevalence of diabetes, hypertension and smoking, and dietary intake of calories and fats in cases and controls. Dietary iron intake was 11.2 +/- 3.4 mg/day in cases and 11.3 +/- 3.8 mg/day in controls (p > 0.05). Serum fasting glucose, cholesterol, LDL cholesterol, HDL cholesterol and triglycerides were not significantly different in cases and controls (p > 0.05). LDL/HDL ratio (4.17 +/- 1.4 vs. 4.62 +/- 2.3) and total cholesterol/HDL ratio (6.47 +/- 1.6 vs. 6.91 +/- 2.4) were also similar. In the whole study group serum iron (54.8 +/- 35.7 mcg/dl), transferrin (11.6 +/- 7.4%) and ferritin (52.4 +/- 57.8 ng/ml) levels were low. In cases as compared to controls serum iron (56.9 +/- 31 vs. 49.6 +/- 45 mcg/dl; z = 1.707, p = 0.088) and transferrin saturation (12.5 +/- 7.8 vs. 9.5 +/- 6.2%; z = 1.83, p = 0.066) were slightly more. Ferritin levels (48.8 +/- 55 vs. 60.9 +/- 64 ng/ml; z = 2.048, p = 0.040) as well as FTR (5.51 +/- 8.6 vs 7.47 +/- 6.1, z = 2.054, p = 0.040) was significantly lower in cases.

CONCLUSIONS

In Indian CHD patients the body iron stores are lower as compared to controls.

A clinical study of the patients with dengue hemorrhagic fever during the epidemic of 1996 at Lucknow, India

This paper describes the clinical findings in 206 patients with dengue fever (DF) or with dengue hemorrhagic fever (DHF) during the epidemic of 1996 at Lucknow. The age group affected most was 11 to 30 years and 21% of the patients were less than 10 years old. The male:female ratio was 1.9:1. The onset was abrupt in all the patients, severe frontal headache was observed in 97%, myalgia in 90%, skin rash in 40%, vomiting in 29% and arthralgia in knee and hip joints in 9%. Anuria was seen in two patients. Lymphadenopathy was noted in 14%, hepatomegaly in 4%, being associated with mild jaundice in one patient, and splenomegaly in 2% of the patients. Involvement of the heart and lungs was seen in one patient each and no case with encephalitis was recorded. Hemorrhages from various sites were observed in 54% patients and 17 patients had profound shock. The commonest bleeding site was gums. Profound shock was preceded by various warning signs, the commonest being sudden hypotension. Among the patients with profound shock the mortality was 47% while the overall fatality rate was 3.8%. A number of the risk factors existed for a long time in this part of the world, but what precipitated the present epidemic at this time, is not known.

Sequential production of cytokines by dengue virus-infected human peripheral blood leukocyte cultures

The study was undertaken to elucidate the sequence of appearance of T helper (Th)1- and Th2-type cytokines in human peripheral blood leucocyte cultures infected in vitro with dengue type 2 virus. Commercial sandwich enzyme-linked immunosorbent assay kits were used to assay the levels of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-2, IL-4, IL-5, IL-6, and IL-10 in culture supernatants. Culture supernatants were also screened for the cytotoxic factor and the dengue virus titres determined. The cytokines that appeared in the culture supernatants on the first day post-infection (p.i.) were cytotoxic factor, TNF-alpha, IL-2, and IL-6; their levels were highest on the second day p.i. IFN-gamma appeared on the second day with a peak on the third day p.i. The levels of these cytokines declined quickly, except for human cytotoxic factor (hCF) and IL-2. The cytokines that appeared later were IL-10 and IL-5 on the fourth day and IL-4 on the sixth day p.i. Dengue virus replicated in the peripheral blood leucocyte (PBL) cultures and was present throughout the course of the study. The findings of the present study show that dengue virus induced a predominant Th1-type cytokine response during the first 3 days of infection of PBL cultures that was replaced by a Th2-type response later.

Sequential production of cytokines by dengue virus-infected human peripheral blood leukocyte cultures

The study was undertaken to elucidate the sequence of appearance of T helper (Th)1- and Th2-type cytokines in human peripheral blood leucocyte cultures infected in vitro with dengue type 2 virus. Commercial sandwich enzyme-linked immunosorbent assay kits were used to assay the levels of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-2, IL-4, IL-5, IL-6, and IL-10 in culture supernatants. Culture supernatants were also screened for the cytotoxic factor and the dengue virus titres determined. The cytokines that appeared in the culture supernatants on the first day post-infection (p.i.) were cytotoxic factor, TNF-alpha, IL-2, and IL-6; their levels were highest on the second day p.i. IFN-gamma appeared on the second day with a peak on the third day p.i. The levels of these cytokines declined quickly, except for human cytotoxic factor (hCF) and IL-2. The cytokines that appeared later were IL-10 and IL-5 on the fourth day and IL-4 on the sixth day p.i. Dengue virus replicated in the peripheral blood leucocyte (PBL) cultures and was present throughout the course of the study. The findings of the present study show that dengue virus induced a predominant Th1-type cytokine response during the first 3 days of infection of PBL cultures that was replaced by a Th2-type response later.

Profile of transforming growth factor-beta 1 in patients with dengue haemorrhagic fever

The pathogenesis of dengue haemorrhagic fever (DHF) is incompletely understood but it has been suggested that various cytokines may have a role in the process. In this study the profile of the cytokine Transforming Growth Factor-beta 1 (TGF-beta1) was investigated in the sera of 79 patients with various grades of dengue illness and in 21 normal healthy controls. Also, TGF-beta1-specific mRNA was examined in their peripheral blood mononuclear cells (PBMC). The results showed that neither TGF-beta1 protein nor its mRNA were detected in healthy controls. In dengue patients, the TGF-beta1 protein and its mRNA were detected in 96%. However, among the patient groups, the levels of TGF-beta1 were lowest in patients with dengue fever (DF; mean value 315 +/- 95 pg/ml) and were highest in patients with DHF grade IV (mean value 1350 +/- 280 pg/ml; P = < 0. 001). The cytokine appeared during the first four days of illness (304 +/- 90 pg/ml) and gradually increased, reaching peak levels (1050 +/- 215 pg/ml) after the 9th day of the illness. Thus TGF-beta1 in the sera and TGF-beta1-mRNA in the PBMC were present in most of the patients with dengue (96%) but the cytokine levels were highest during the later periods of illness and in patients with DHF grade IV, suggesting a possible role of TGF-beta1 in the pathogenesis of DHF.

Elevated levels of IL-8 in dengue hemorrhagic fever

Dengue virus causes dengue fever, a mild febrile illness, and at times dengue hemorrhagic fever (DHF), a severe illness the pathogenesis of which is not fully understood. Given the crucial roles played by interleukin-8 (IL-8) as a chemoattractant cytokine and in inflammatory processes, levels of circulating IL-8 in the sera and IL-8 mRNA in the peripheral blood mononuclear cells (PBMC) were measured in 99 patients of a recent dengue epidemic that occurred in India in 1996 and in 21 normal healthy controls. Twenty-six of the patients had dengue fever (DF) and the remaining 73 were diagnosed as having different grades of DHF. All the control normal sera were negative for IL-8, so were their PBMC for IL-8 mRNA. Increased levels of IL-8 in the sera and IL-8 mRNA in their PBMC were observed in patients with severe illness of DHF grades III and IV. Only two out of 26 patients of DF and one out of 10 DHF grade I patient were positive for IL-8 and all three deteriorated to DHF grade IV within 24 hr. All six patients of DHF grade IV who died had higher serum level of IL-8 above 200 pg/ml, the highest being 5,568 pg/ml in one patient; the presence of mRNA for IL-8 was very high in all patients. A striking correlation was observed between increased levels of IL-8 and severe DHF, with greater levels in patients with increased grade of the disease and death. These results suggest that IL-8 may have an important role and may be an indicator of increasing severity of the disease and death.

Antioxidant phenolics and flavonoids in common Indian foods

To determine antioxidant phenolics and flavonoids in commonly consumed Indian foods we chemically analysed 85 food-stuffs comprising of cereals, pulses, nuts, oilseeds, vegetables, fruits and beverages. Total phenolics were measured biochemically and flavonoids were measured as a sum of quercetin, kaempferol, luteolin and pelargonidin. High flavonoid content (> 100 mg/100 gm) was present in tea, coffee, apple, guava, terminalia bark, fenugreek seeds, mustard seeds, cinnamon, red chili powder, cloves and turmeric. Medium levels (50-100 mg) were found in Indian gooseberry, omum, cumin, cardamom, betel leaf and brandy. Small but significant amounts were also present in food-items of large consumption such as kidney beans, soyabeans, grapes, ginger, coriander powder, bajra and brinjal.

Production of cytotoxic factor by peripheral blood mononuclear cells (PBMC) in patients with dengue haemorrhagic fever

A unique cytokine, human cytotoxic factor (hCF), has been shown to occur in the sera of patients with dengue fever (DF) and dengue haemorrhagic fever (DHF). The present study was undertaken to investigate the ability of fresh PBMC of such patients to produce hCF. The PBMC were cultured for 24 h and the culture supernatants (CS) were analysed for the presence of hCF by cytotoxicity assay, competitive ELISA and dot blot tests. In 90% of 246 cases CS were positive for hCF by the three tests. CS were positive for hCF in PBMC collected from days 1-20 of illness but not at later periods. Higher cytotoxic activity was observed in CS of days 1-4 of illness and was highest in cases of DHF grade IV and lowest in cases of DF. Dot blot hybridization of RNA extracted from the PBMC of the patients showed the presence of mRNA for hCF in 94% of cases. A similar number of patients showed the presence of hCF in situ in the PBMC smears by fluorescent antibody technique. hCF was found only in CD4+ T cells. The findings thus present direct evidence of the production of hCF by CD4 T cells of cases of DF/DHF.

Pure phase-modulation mode locking in semiconductor lasers

Pure phase-modulation mode locking of an extended-cavity semiconductor laser, operating near 1.5 microm, is demonstrated. The mode-locked laser uses a two-section optical amplifier that provides both gain and phase modulation.

Frequency-modulation mode locking of a semiconductor laser

We report FM mode locking in an extended-cavity semiconductor laser containing a tunable distributed Bragg reflector gain medium operating near 1.5 microm. We demonstrate the generation of pulses with 24-ps duration at a repetition rate of 1.5 GHz.

Synthetic and pharmacological studies on some transition metal chelates involving N-pyrimidino benzamide-2-carboxylic acid as ligand

N-pyrimidino benzamide-2-carboxylic acid (NPBCA) and its Cu(II), Ni(II), Co(II), Zn(II), and Mn(II) chelates have been synthesized and characterized by using elemental analyses, molar conductance, molecular weight determination, magnetic moment, infrared, and electronic spectra. Antifungal activity of the synthesized compounds has been screened on common fungi, viz., Aspergillus niger, Aspergillus nidulense, and Candida albicans at 28 degrees C and antibacterial activity has been observed on gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria at 37 degrees C. Anti-inflammatory and ulcerogenic potential of the synthesized compounds have been discussed.

Syntheses, characterization, and microbial activity of some transition metal complexes involving potentially active O and N donor heterocyclic ligands

The formation of binary as well as ternary metal complexes of type MLL' (where M(II) = Cu(II), Ni(II), Co(II), and Zn(II); L = 8-hydroxyquinoline, and L' = 2-furoic acid) has been studied. The complexes were synthesized and characterized by elemental analyses, molecular weight determination, the IR and electronic spectra, conductivity, and magnetic measurements. The presence of coordinated water molecules was demonstrated by thermogravimetric analysis. The microbial activity of these ligands and their metal complexes was determined on gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria, the antifungal activity on some common fungi, viz. Aspergillus niger, Aspergillus nidulense, and Penicillium citrinum.

Structural and microbial studies of some transition metal complexes

N-pyridinobenzamide-2-carboxylic acid has been synthesized. Its binary and ternary (using 8-hydroxy-quinoline as the other ligand) Cu(II), Ni(II), Co(II), and Zn(II) complexes have been synthesized and characterized by their elemental analysis, molecular weight determination, molar conductance, infrared and electronic spectral data, and magnetic measurements. Antibacterial activity of these ligands and their metal complexes has been determined on gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria at 37 degrees C, and antifungal activity has been determined on common fungi viz. Aspergillus niger, Aspergillus nidulense, and Candida albicans at 28 degrees C. A considerable increase in the biocidal activity of these ligands on being coordinated with metal ions has been reported.

Macrophage functions during dengue virus infection: antigenic stimulation of B cells

This study was undertaken to investigate the function of dengue type 2 virus (DV)-infected mouse peritoneal macrophages (M phi) regarding the antigenic stimulation of B lymphocytes of the spleen. It was observed that a variable proportion of M luminal diameter show DV-specific immunofluorescent antigen, which depended upon the route of administration of the virus, being higher in i.p.-inoculated mice and in vitro-infected M luminal diameter monolayers. The DV-infected M luminal diameter presented the DV antigen to B cells in vitro and in vivo, leading to their clonal expansion as shown by counting the virus-specific IgM antibody plaque-forming cells (PFC). The PFC response depended upon the number of DV-infected M luminal diameter. The antigen was presented equally well both by I-A-negative and I-A-positive M luminal diameter. Superimposition of a heterologous antigen (Coxsackie B4 virus) in a Mackaness type of experiment depressed the capacity of M luminal diameter to present both the homologous as well as heterologous antigen.

Variable effects of dengue virus-induced cytotoxic factors on different subpopulations of macrophages

Dengue virus (DV) induces T lymphocytes of the spleen to produce a cytotoxic factor (CF) that induces a subpopulation of macrophages (M phi) to produce a soluble cytotoxin (CF2). Both these factors kill normal lymphoid cells and M phi. The present study was undertaken to investigate the effects of these factors on the I-A-positive and I-A-negative subpopulations of mouse peritoneal M phi. It was observed that CF kills I-A-negative M phi and induces I-A-positive M phi to produce the CF2 that kills both types of cells. However, even when combined together, CF and CF2 do not kill 100% of the M phi. The two-step mechanism involving co-operation between T cells and M phi appears to be biologically economical for maintaining the cytotoxic pathway.

Effect of dengue virus-induced cytotoxic factor on Fc-receptor functions of mouse macrophages

Many defects in macrophage functions in dengue type 2 virus (DV) infection have been shown to be mediated by production of the virus-induced cytotoxic factor (CF). An attempt has been made to determine whether the alterations in Fc-mediated functions of macrophages in DV-infected mice are due to CF. Mice given CF intravenously show a rapid fall in total numbers of peritoneal and spleen cells. The number of cells in the peritoneal cavity recovered in 48 h. but recovery in the spleen was not significant. The capacity of the splenic and peritoneal macrophages to attach and ingest opsonized sheep erythrocytes was significantly reduced, the lowest values of attachment index (AI) and phagocytic index (PI) being observed within 2-3 h. At later periods the AI values increased markedly but the PI values remained depressed. The effect was dose-dependent. The effect on Fc-receptor functions of macrophages in DV-infected mice thus appears to be mediated through CF.

Effect of dengue virus infection on Fc-receptor functions of mouse macrophages

Fc-receptor-mediated attachment and ingestion of opsonized sheep erythrocytes (EA) by the macrophages of spleen and peritoneal cavity were studied during dengue virus type 2 (DV) infection of Swiss albino mice. Following intracerebral inoculation, virus antigen could be demonstrated by immunofluorescence in the splenic macrophages from day 4 and in peritoneal macrophages from day 5 post-infection, with a higher number of positive cells discernible on the 7th and 8th days. The virus could be isolated from spleen tissue from day 5. The total number of cells was markedly reduced from day 4 onwards both in the spleen and peritoneal cavity. A loss in the capacity to attach and ingest EA was noticed, the lowest values of attachment index (AI) and phagocytic index (PI) being reached on day 4. At later periods the AI values increased markedly but continued to be significantly less than those in uninfected control mice. The PI values continued to be lower throughout. The dichotomy between the Fc-mediated attachment and ingestion may be a mechanism for prevention of virus infection of macrophages.