Disease-Suppressive Soils-Beyond Food Production: a Critical Review.

In the pursuit of higher food production and economic growth and increasing population, we have often jeopardized natural resources such as soil, water, vegetation, and biodiversity at an alarming rate. In this process, wider adoption of intensive farming practices, namely changes in land use, imbalanced fertilizer application, minimum addition of organic residue/manure, and non-adoption of site-specific conservation measures, has led to declining in soil health and land degradation in an irreversible manner. In addition, increasing use of pesticides, coupled with soil and water pollution, has led the researchers to search for an environmental-friendly and cost-effective alternatives to controlling soil-borne diseases that are difficult to control, and which significantly limit agricultural productivity. Since the 1960s, disease-suppressive soils (DSS) have been identified and studied around the world. Soil disease suppression is the reduction in the incidence of soil-borne diseases even in the presence of a host plant and inoculum in the soil. The disease-suppressive capacity is mainly attributed to diverse microbial communities present in the soil that could act against soil-borne pathogens in multifaceted ways. The beneficial microorganisms employ some specific functions such as antibiosis, parasitism, competition for resources, and predation. However, there has been increasing evidence on the role of soil abiotic factors that largely influence the disease suppression. The intricate interactions of the soil, plant, and environmental components in a disease triangle make this process complex yet crucial to study to reduce disease incidence. Increasing resistance of the pathogen to presently available chemicals has led to the shift from culturable microbes to unexplored and unculturable microbes. Agricultural management practices such as tillage, fertilization, manures, irrigation, and amendment applications significantly alter the soil physicochemical environment and influence the growth and behaviour of antagonistic microbes. Plant factors such as age, type of crop, and root behaviour of the plant could stimulate or limit the diversity and structure of soil microorganisms in the rhizosphere. Further, identification and in-depth of disease-suppressive soils could lead to the discovery of more beneficial microorganisms with novel anti-microbial and plant promoting traits. To date, several microbial species have been isolated and proposed as key contributors in disease suppression, but the complexities as well as the mechanisms of the microbial and abiotic interactions remain elusive for most of the disease-suppressive soils. Thus, this review critically explores disease-suppressive attributes in soils, mechanisms involved, and biotic and abiotic factors affecting DSS and also briefly reviewing soil microbiome for anti-microbial drugs, in fact, a consequence of DSS phenomenon.

Vector density and the control of kala-azar in Bihar, India.

Bihar, India has been in the grip of kala-azar for many years. Its rampant and severe spread has made life miserable in most parts of the state. Such conditions require a comprehensive understanding of this affliction. The numbers coming out of the districts prone to the disease in the north and south Ganges have provided us with several startling revelations, as there are striking uniformities on both sides, including similar vegetation, water storage facilities, house construction and little change in risk factors. The northern areas have been regularly sprayed with DDT since 1977, but eradication of the disease appears to be a distant dream. In 2007 alone, there were as many as 37,738 cases in that region. In contrast, the southern districts of Patna and Nalanda have never had the disease in its epidemic form and endemic disease has been present in only some pockets of the two districts. In those cases, two rounds of spraying with DDT had very positive results, with successful control and no new established foci. In addition, an eleven-year longitudinal study of the man hour density and house index for the vector Phlebotomus argentipes demonstrated that they were quite high in Patna and Nalanda and quite low in north Bihar. Given these facts, an attempt has been made to unravel the role of P. argentipes saliva (salivary gland) in the epidemiology of kala-azar. It was determined that patchy DDT spraying should be avoided for effective control of kala-azar.

Purification and characterization of an acidic trypsin/subtilisin inhibitor from tortoise egg white.

Egg whites of three species of tortoise and turtle have been compared by gel chromatography for inhibitory activity against proteases. The egg white of Geomyda trijuga trijuga Schariggar contains trypsin/subtilisin inhibitor while the egg white of Caretta caretta Linn. contains both trypsin and chymotrypsin inhibitors. No protease inhibitory activity has been detected in the egg white of Trionyx gangeticus Cuvier. An acidic trypsin/subtilisin inhibitor has been purified to homogeneity from the egg white of tortoise (G. trijuga trijuga). It is a single polypeptide chain of 100 amino acid residues, having a molecular weight of 11,700. It contains six disulphide bonds and is devoid of methionine and carbohydrate moiety. Its isoelectric point is at pH 5.95 and is stable at 100 degrees C for 4 hr at neutral pH. The inhibitor inhibits both trypsin and subtilisin by forming enzyme-inhibitor complexes at a molar ratio close to unity. Their dissociation constants are 7.2 x 10(-9) M for bovine trypsin and 5.5 x 10(-7) M for subtilisin. Chemical modification of amino groups with trinitrobenzene sulfonate has reduced its inhibitory activities against both trypsin and subtilisin, but the loss of its trypsin inhibitory activity is faster than that of its subtilisin inhibitory activity. It has independent binding sites for inhibition of trypsin and subtilisin.

Surface hydrophobicity of a low molecular weight basic trypsin subtilisin inhibitor from marine turtle eggwhite.

Surface hydrophobicity has recently been emphasized as an important parameter for functional correlation of proteins. However, evaluations of the parameter by different experimental techniques often do not correlate well with each other. In this paper we have compared surface hydrophobicity of a basic protein with those of beta-lactoglobulin, ovalbumin and lysozyme by fluorescence probe method using ANS as an external probe. Two different fluorimetric approaches to determining the surface hydrophobicity parameter, namely, the slope method and the binding parameter method, follow the same relative order. Denaturants, urea, and guanidine hydrochloride disrupted the hydrophobic clefts of the inhibitor on the surface, causing a drastic reduction of surface hydrophobicity.

The burden of diabetes and impaired fasting glucose in India using the ADA 1997 criteria: prevalence of diabetes in India study (PODIS).

This random multistage cross sectional population survey was undertaken to determine the prevalence of diabetes mellitus (DM) and impaired fasting glycemia/glucose (IFG) in subjects aged 25 years and above in India. The study was carried out in 108 centers (49 urban and 59 rural) to reflect the size and heterogeneity of the Indian population. 41,270 (20,534 males and 20,736 females) subjects were studied. 21,516 (10,865 males and 10,651 females) were from urban areas and 19,754 (9669 males and 10,085 females) from rural areas. Blood samples were taken after a fast of 10-12h and the subjects were categorized as having IFG or DM using the 1997 American Diabetes Association criteria. The age and gender standardized prevalence rate for DM and IFG in the total Indian population was 3.3 and 3.6% respectively (P < 0.001). The standardized prevalence of DM and IFG in urban areas was significantly higher than that for the rural population (urban DM prevalence 4.6% versus rural DM prevalence 1.9%, P < 0.001; urban IFG prevalence 4.8% versus rural IFG prevalence 2.5%, P < 0.001). There was no statistically significant difference in the prevalence between DM (4.6%) and IFG (4.8%) in the urban population. The rural prevalence of IFG (2.5%) was significantly (P <0.001) more than the rural prevalence of DM (1.9%). Type 2 diabetes is a major health problem is India.

Comparing the ADA 1997 and the WHO 1999 criteria: Prevalence of Diabetes in India Study.

This random multistage cross-sectional population survey was undertaken to determine the prevalence of type 2 diabetes mellitus (DM) in subjects aged 25 years and above in India. The study was carried out in 77 centres (42 urban and 35 rural) to reflect the size and heterogeneity of the Indian population. 18,363 (9008 male and 9355 female) subjects were studied. 10,617 (5379 males and 5238 females) were from urban areas and 7746 (3629 males and 4117 females) from rural areas. Blood samples were taken after a fast of 10-12 and 2 h after 75 g of oral glucose. Subjects were categorized as having impaired fasting glycemia (IFG) or DM using the 1997 ADA or having impaired glucose tolerance (IGT) or DM using the 1999 WHO criteria. The age- and gender-standardized prevalence rate for DM using the ADA criteria was 3.6% whilst that using the WHO criteria was 4.3% (P < 0.001). The respective standardized prevalence of DM, using the two criteria was, 4.7 and 5.6%, respectively (P < 0.001) in the urban Indian population and 2.0 and 2.7% (P < 0.02) in the rural Indian population. Using the WHO criteria, 581 subjects were newly diagnosed whilst the ADA criteria newly diagnosed 437 subjects. The respective numbers for the urban population were 425 and 323, and for the rural population were 146 and 114, respectively. The ADA criteria could diagnose 75.2, 76.0 and 73.0% of the subjects who had DM as per the WHO criteria. Of 739 Indian subjects who had IFG, 106 (14.3%) were diagnosed as having DM by the WHO criteria whilst 505 (68.3%) had values compatible with a diagnosis of IGT. Of the 536 urban subjects with IFG, 74 (13.8%) had DM and 350 (65.3%) had IGT using the WHO criteria. Of the 302 rural subjects with IFG, 32 (15.8%) had DM and 155 (76.3%) had IGT using the WHO criteria. 505 (49.9%) of 1012 Indian subjects with IGT as per the WHO criteria had IFG. 350 (47.7%) of 733 urban subjects and 155 (55.5%) of 279 rural subjects with IGT had values compatible with IFG as per the ADA criteria. Type 2 diabetes is a major health problem is India. The use of the ADA criteria would underestimate the prevalence of DM by not diagnosing subjects showing a poor response to a glucose challenge. This along with the discrepancies between subjects showing IGF or IGT could be a challenge to any prevention program.

The burden of diabetes and impaired glucose tolerance in India using the WHO 1999 criteria: prevalence of diabetes in India study (PODIS).

This random multistage cross-sectional population survey was undertaken to determine the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in subjects aged 25 years and above in India. The study was carried out in 77 centers (40 urban and 37 rural). 18363 (9008 males and 9355 females) subjects were studied. 10617 (5379 males and 5238 females) were from urban areas and 7746 (3629 males and 4117 females) from rural areas. Blood samples were taken after a fast of 10-12 h and 2 h after 75 g of oral glucose. Subjects were categorized as having IGT or DM using the World Health Organisation (WHO) (1999) criteria. The standardized prevalence rate for DM in the total Indian, urban and rural populations was 4.3, 5.9 and 2.7%, respectively. The corresponding IGT rates in the three populations was 5.2, 6.3 and 3.7%, respectively. The urban prevalence of DM and IGT was significantly greater than in the rural population (P < 0.001 in both instances). The prevalence of DM was significantly, more than that of IGT (P < 0.001) within both the rural and urban populations. Type 2 diabetes is a major health problem is India.

Field trial of an ecological approach for the control of Phlebotomus argentipes using mud & lime plaster.

A pilot study for the control of Ph. argentipes, a known vector of kala-azar in India, was carried out using an ecological approach. Of the 15 houses selected for the study 10, including the cattle sheds and latrines, were plastered with a mixture of mud and lime, up to a height of 1.22 m taking care to seal all cracks and crevices. The remaining five houses were left unplastered and were considered as control areas. The pre-treatment and post-treatment resting densities of the sandfly were monitored both in treated and untreated houses. A sudden drop in the sandfly density was noticed in the treated houses, whereas there was no significant reduction in the check houses, suggesting an effective control.

Physical and chemical characterization of macroglobulin from marine turtle eggwhite.

Macroglobulin was purified from the eggwhite of the marine turtle (Caretta caretta Linn.) by gel filtration through Sephadex G-200 and Sepharose 4B. It was characterized by physical techniques including sedimentation velocity, diffusion and viscosity. Its molecular weight (Mr) was determined as 724,000 with four subunits of equal molecular weight. A large amount of water was hydrodynamically associated with the macroglobulin. It inhibited the activities of trypsin and papain and did not cross-react with human alpha 2-macroglobulin. Its amino acid composition was similar to that of human alpha 2-macroglobulin. Results suggest that turtle eggwhite macroglobulin is a homologous but distinct protein from human alpha 2-macroglobulin.

Effect of propranolol on ECG of Myna, Acridotheres tristis, and Goh, Varanus bengalensis.

Effect of propranolol (1 and 3 mg/kg body wt), a sympathetic blocking agent, on ECG patterns was studied in Varanus and Acridotheres. ECG was recorded before and after 5 min (immediate), 15 min and in some cases 25 min of drug infusion. All animals responded to propranolol with bradycardia. The effectiveness is dose dependent and it is also associated with the high heart rate both in Acridotheres and in Varanus. The P-R or P-S interval increased in all cases of Varanus after infusion. In Acridotheres height and duration of P-wave were increased slightly with the lower dose and decreased with the higher dose. The Q-S shortened with the lower dose and widened late with the higher dose in Varanus whereas in Acridotheres it is widened with lower and higher doses of propranolol. The Q-T interval has been increased in both groups of animals. An increased amplitude of T-wave height was observed in Varanus after 5 and 15 min of drug infusion. But it was noted with decrease in amplitude under high dose after 15 min of drug infusion. In Acridotheres it was on increase with lower dose and decrease with higher dose. The delta-wave disappeared after the administration of propranolol in Acridotheres.(ABSTRACT TRUNCATED AT 250 WORDS)

Vectorial efficacy of Phlebotomus argentipes in Kala-azar endemic foci of Bihar (India) under natural and artificial conditions.

Ability of Phlebotomus argentipes to acquire Leishmania donovani the causative agent of Indian Kala-azar was evaluated in the laboratory. Flies were fed artificially on infected blood suspensions, using a chick-skin-membrane feeding apparatus, and naturally on Leishmania donovani infected mice. In addition flies collected from different endemic areas were dissected and examined for natural infection. Flies fed on infected mice showed significantly higher feeding rate (14.4%, p < 0.01) compared to that of other experiments (9%, 8.75%) but the percentage of infection was very low (2.43%). No Chi-square comparison was made between infection rate and feeding rate because of low value in infection rate (less than 5). Flies dissected for natural infection showed only 0.1% infection. Not much difference was observed in the intensity of Leishmania donovani infection in the mid gut of sandflies examined from any of these experiments. These observations have confirmed that Phlebotomus argentipes has ability to acquire infection and it provides the final piece of evidence that Phlebotomus argentipes is the vector of Leishmania donovani in Bihar State.