Antibacterial activity of grapefruit peel extracts and green-synthesized silver nanoparticles.

BACKGROUND AND AIM: The gradual loss of efficacy of conventional antibiotics is a global issue. Plant material extracts and green-synthesized nanoparticles are among the most promising options to address this problem. Therefore, the aim of this study was to assess the antibacterial properties of aqueous and hydroalcoholic extracts of grapefruit peels as well as their inclusion in green-synthesized silver nanoparticles (AgNPs). MATERIALS AND METHODS: Aqueous and hydroalcoholic extracts (80% v/v) were prepared, and the volume and mass yields were determined. The synthesis of AgNPs was done in an eco-friendly manner using AgNO3 as a precursor. The nanoparticles were characterized by ultraviolet-vis spectrometry and photon cross-correlation spectroscopy. The antibacterial activity of the extracts was tested on three Gram-positive bacteria (Staphylococcus aureus ATCC 6538, clinical Enterococcus faecalis, and S. aureus) and two Gram-negative bacteria (two clinical Escherichia coli) using various concentrations of extracts (100, 50, 25, 12, and 5 mg/mL and 5% dimethyl sulfoxide as negative control). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the microdilution method. Modulation of cefazoline and ampicillin on resistant E. coli and S. aureus strains was added to the mixture design response surface methodology with extreme vertices design, with the diameters of inhibition and the fractional inhibitory concentration index as responses and factors, respectively. The antibiotic, the ethanolic extract, and water varied from 0.1 MIC to 0.9 MIC for the first two and from 0 to 0.8 in proportion for the third. Validating the models was done by calculating the absolute average deviation, bias factor, and accuracy factor. RESULTS: The volume yield of the EE and aqueous extract (AE) was 96.2% and 93.8% (v/v), respectively, whereas their mass yields were 7.84% and 9.41% (m/m), respectively. The synthesized AgNPs were very uniform and homogeneous, and their size was dependent on the concentration of AgNO3. The antibacterial activity of the two extracts was dose-dependent, and the largest inhibition diameter was observed for the Gram-positive bacteria (S. aureus ATCC 6538; AE, 12; EE, 16), whereas AgNPs had a greater effect on Gram-negative bacteria. The MICs (mg/mL) of the AEs varied from 3.125 (S. aureus ATCC 6538) to 12.5 (E. coli 1 and E. coli 2), whereas the MICs of the EEs varied from 1.5625 (S. aureus 1, S. aureus ATCC 6538, and E. faecalis) to 6.25 (E. coli 1). There was a significant difference between the MICs of AEs and EEs (p=0.014). The MBCs (mg/mL) of the AEs varied from 12.5 (S. aureus ATCC 6538) to 50 (S. aureus 1), whereas those of the EEs varied from 6.25 (S. aureus 1) to 25 (E. coli 1 and E. faecalis). Ethanolic grapefruit extracts demonstrated an ability to modulate cefazolin on E. coli and S. aureus but were completely indifferent to ampicillin on E. coli. CONCLUSION: Grapefruit peel extracts and their AgNPs exhibit antibacterial properties that can be exploited for the synthesis of new antimicrobials and their EEs may be efficiently used synergistically with other antibiotics against bacteria with intermediate susceptibility.

Methods for establishing a surveillance system for cardiovascular diseases in Indian industrial populations.

OBJECTIVE: To establish a surveillance network for cardiovascular diseases (CVD) risk factors in industrial settings and estimate the risk factor burden using standardized tools. METHODS: We conducted a baseline cross-sectional survey (as part of a CVD surveillance programme) of industrial populations from 10 companies across India, situated in close proximity to medical colleges that served as study centres. The study subjects were employees (selected by age and sex stratified random sampling) and their family members. Information on behavioural, clinical and biochemical determinants was obtained through standardized methods (questionnaires, clinical measurements and biochemical analysis). Data collation and analyses were done at the national coordinating centre. FINDINGS: We report the prevalence of CVD risk factors among individuals aged 20-69 years (n = 19 973 for the questionnaire survey, n = 10 442 for biochemical investigations); mean age was 40 years. The overall prevalence of most risk factors was high, with 50.9% of men and 51.9% of women being overweight, central obesity was observed among 30.9% of men and 32.8% of women, and 40.2% of men and 14.9% of women reported current tobacco use. Self-reported prevalence of diabetes (5.3%) and hypertension (10.9%) was lower than when measured clinically and biochemically (10.1% and 27.7%, respectively). There was marked heterogeneity in the prevalence of risk factors among the study centres. CONCLUSION: There is a high burden of CVD risk factors among industrial populations across India. The surveillance system can be used as a model for replication in India as well as other developing countries.

Incidence of Campylobacter species in animal handlers.

From the stool samples collected from diarrhoeic and healthy handlers of domestic animals different Campylobacter species were isolated in 16.6 and 21.1 per cent respectively. Both biotypes 1 and 2 were identified. All the 10 strains of C. jejuni were found to be enterotoxigenic or potentially enterotoxigenic in the ligated ileal loop of albino rats.

Prevalence of the type of hepatitis virus in hospitalized jaundiced individuals.

The prevalence of different types of hepatitis virus was estimated in 185 hospitalized jaundiced patients. It was found that 41.08% were positive for HBs Ag by ELISA method. The jaundiced group was also tested for IgM antibody and for total antibodies (IgG and IgM) to HAV infection by ELISA method and 5.40% were found to be positive. All patients in the jaundiced group had serum bilirubin above normal values. It was, therefore, assumed that the rest 52.92% were suffering from Non A Non B virus infection.

Enterotoxigenicity of human and animal isolates of Campylobacter jejuni in ligated rat ileal loops.

Human and animal isolates of Campylobacter jejuni were tested for enterotoxigenicity in ligated loop of Charles-Foster rats. Of 21 isolates, 13 were proved to be toxin-positive in the initial experiments. However, the remaining 8 required one to three passages through the rat ileal loop before showing the capacity to produce enterotoxin. All isolates caused fluid accumulation comparable with the amount produced by the standard toxigenic strain of Vibrio cholerae 01 1naba 569B. The isolates of C. jejuni from human and animal sources did not show any quantitative difference in their capacity to produce enterotoxin.

Occurrence of salmonellae in slaughtered pigs, goat meat, meat handlers and slaughtered-house workers.

Of 413 samples comprising 200 goat meat, 100 pig's faeces, 50 faeces of slaughtered-house workers, 13 faeces and 50 nailwashings of goat meat handlers collected from different shops of Calcutta Corporation, 25 (6.05 per cent) yielded 13 serotypes of salmonellae. The commonest serotypes was S. newport (24 per cent), followed by S. enteritidis (12 per cent), S. anatum (12 per cent) and S. typhimurium. Isolation rate of salmonellae was 12 (6 per cent) from goat meat, 10 (10 per cent) in pig's faeces and 3 (6 per cent) in nailwashings. S. newport (50 per cent) in goat meat and S. anatum (30 per cent) in faecal contents of pigs were the predominant serotypes. None of the faecal samples of goat meat handlers and slaughtered-house workers yielded salmonellae.

Seroepidemiological study of Japanese encephalitis in Dimapur, Nagaland.

A seroepidemiological study of Japanese encephalitis (JE) in Dimapur, Nagaland was carried out following an outbreak of the disease between July, 1985 and February, 1986. Altogether 50 persons were affected with 30 (60 per cent) deaths. The attack and death rates per 1000 were more in Nagas viz. 0.55 and 0.34 than non-Nagas viz. 0.33 and 0.20 respectively. All ages and both sexes were affected. Of the nine mosquito species encountered Culex vishnui showed the highest density (44.5/MH). Culture of mosquito pool did not yield any viral agent. A total of 311 serum samples comprising 95 humans, 166 animals and 50 birds were tested for the presence of haemagglutination inhibition (HI) antibodies against Chikungunya and three flavirus antigens, viz. JE, WN and DEN-2. The overall flavivirus HI antibody in humans was positive in 26 (27.3 per cent) almost identical to JE antibody prevalence. The per cent positivity of HI antibodies to JE, WN and DEN-2 were 42.2 per cent, 22.2 per cent and 13.3 per cent in the affected and 14.2 per cent, 10 per cent and 6 per cent in the unaffected area. The activity of Alpha (Chikungunya) virus though very low was significantly higher (chi 2 = 5.57) in the affected area. The prevalence of JE antibody was 77.7 per cent in dogs, 52 per cent in cattle, 34 per cent in pigs and 21.1 per cent in goats. Of the five species of birds, flavivirus and JE antibodies were detected in 21.4 per cent pigeons and 22.2 per cent heron egrettes. Neutralisation test established the distinct role of JE virus over other related flavivirus antigens.

A cross-national study of the effect of intercaste marriage on fertility in India and the United States.

The purpose of this study was 1) to determine the effects of intercaste marriages on fertility in India (high-low caste marriage) and the United States (white-black marriage); and 2) to compare the demographic characteristics of intercaste married couples in India and the United States. The sample consisted of 366 intercaste and intracaste married couples in India and the U.S. The data revealed that in both countries intercaste married couples had a significantly lower number of children than intracaste married couples at .001 level of significance (as between Brahmin or Chamar subcaste in India and as between whites and whites and between blacks and blacks in the U.S.). In both countries, high caste husband-low caste wife had more children (India 1.8, U.S. 1.5) than high caste wife-low caste husband (India 1.5, U.S. 1.1). The main conclusion was that intercaste marriages produced fewer children than intracaste marriages in India and the U.S. Additional demographic and socio-psychological factors which contributed to a lower number of children in both countries were: age difference at the time of marriage, educational achievement level of husband and wife, rural or urban place of origin, fear of caste or racial discrimination, and acceptance of the children by the family and the community.

Neutron-activation analysis for thorium in zircon.

The thorium content of zircons and standard rock samples was determined by neutron-activation analysis. The 310-keV photopeak activity of (233)Pa was enhanced by a prior chemical separation which removed interfering induced activities.