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Biomedical subjects

J Sokhey

Publications and source records attributed to J Sokhey.

At least 37 records · Page 2Linked to original sources
PubMed1998

Endemic cholera in Delhi, 1995: analysis of data from a sentinel centre.

Data on cholera cases admitted to the Delhi Infectious Diseases Hospital (IDH) are presented to describe the pattern of occurrence of cholera in Delhi in 1995. Rectal swabs from 4082 cases of acute diarrhoea admitted to the IDH were examined for excretion of Vibrio cholerae. Of them, 2004(49%) and 4(0.1%) were positive for V. cholerae O1 biotype El Tor and V. cholerae O139 respectively. Most cholera cases occurred during May-September (summer and monsoon months). The period from January to March (winter) was completely free from cholera. The urban areas were not affected uniformly. Of the 80 PIN (Postal Index Number) code areas, 10 contributed to 57% of the cases. The early cases were scattered in PIN code areas distant from one another. The hospitalisation rates for cholera were the highest in children aged less than five years and declined significantly with increasing patients' age. Males had significantly higher rates than females aged up to 20 years, whereas the situation was reversed in the 20 to 39 year age group. Four per cent of the affected families had multiple cases. An estimated 1% of the household contacts of hospitalised cases of cholera were themselves hospitalised for cholera within 2 days of the first admission. Of the 260 V. cholerae O1 isolates tested, 4%, 7%, 8%, 89%, 91% and 95% were resistant to tetracycline, nalidixic acid, chloramphenicol, co-trimoxazole, streptomycin, and furazolidone respectively. The study highlights the usefulness of surveillance data to identify groups, urban areas and seasons with increased risk for cholera and to allow control measures to be focussed on those in greatest need.

Adolescent↗
PubMed1998

Alternative approach and evaluation of three potency assay methods for testing adsorbed tetanus toxoid.

Thirteen batches of adsorbed Tetanus Toxoid (TT) from different manufacturers were tested for potency by three different methods viz: (i) An Antibody Induction Method (AIM) developed in mice: (ii) WHO lethal challenge in mice; and (iii) Conventional Antibody Induction (I.P). Method in guinea pigs. The potency results obtained in AIM, by serological evaluation of immunized mice were found identical and correlated significantly with those obtained by WHO recommended lethal challenge test in mice. The potency data obtained in the present study was found comparable with other studies. An AIM in mice thus offers an alternative to lethal challenge tests and can replace guinea pig model. Out of 107 serum samples obtained from immunized guinea pigs in the conventional antibody induction method, 90% samples contained more than 4 units of tetanus antitoxin per ml. End point titres of 42 serum samples belonging to 5 batches of TT also showed much higher tetanus antitoxin content when determined by TN test. The potency data obtained thus suggest revision of the minimum requirement in Indian Pharmacopoeia which is too low and which may be increased as indicated by the present study.

Adsorption↗
PubMed1998

Quantitation of tetanus and diphtheria antitoxins in mouse sera by indirect haemagglutination.

Serum samples obtained from 75 groups of mice immunized with various doses of adsorbed tetanus vaccine, adsorbed diphtheria-tetanus vaccine and adsorbed diphtheria-tetanus-pertussis vaccine were titrated for tetanus antitoxin content by an in-vitro indirect haemagglutination (IHA) and by toxin neutralization test (TN) in mice. From these serum samples of 49 groups of mice which were immunized with combined vaccine containing diphtheria toxoid were titrated for their diphtheria antitoxin content by IHA and by i.d. toxin neutralization test (TN) in guinea pigs. Good correlations were found between the estimates obtained by in-vitro IHA and in vivo TN tests in both tetanus and diphtheria antitoxin titrations. The minimum level of tetanus or diphtheria antitoxin detectable by IHA was 0.00039 IU/ml. It is concluded that IHA is a simple, sensitive and reproducible alternative test which can replace the animal TN tests for the estimation of tetanus and diphtheria antitoxins and could reliably be used in the potency assay of tetanus and diphtheria toxoids of combined vaccines based on antibody induction in mice.

Animals↗
PubMed1996

Adjuvant effect of DEAE-dextran and tetanus toxoid on whole cell heat inactivated phenol preserved typhoid vaccine.

Active mouse protection test (AMPT) and enzyme linked immunosorbent assay (ELISA) were used to determine the immunogenicity of whole cell typhoid vaccine when administered in conjunction with either tetanus toxoid (TT) or DEAE-Dextran (DD). Immunization of mice with whole cell typhoid vaccine showed enhanced potency either when administered in conjunction with TT or DD and values were statistically significant (p < 0.05) in comparison to conventional or standard typhoid vaccines. For ELISA, the mice were immunized with 2 different schedules, one in which a single dose of 0.25 ml subcutaneously (s/c) was administered and in another two doses of 0.25 ml each s/c, 14 days apart. In case of single dose schedule of immunization D vaccine (Whole cell typhoid + 5 mg/ml DD) showed significant increase of immune response (3.201 log10) as compared to plain vaccine (2.550 log10). Two dose schedule further increased the titres to 3.856 log10. DD adjuvanted vaccine showed higher potency by AMPT as compared to the TT adjuvanted vaccine or plain vaccine. The present study clearly demonstrates that a single dose of 0.25 ml which is equivalent to half of the conventionally used single human dose of typhoid vaccine adjuvanted with DD can significantly improve the immunogenicity of the vaccine.

Adjuvants, Immunologic↗
PubMed1996

Isolation of poliovirus from cases of acute flaccid paralysis.

OBJECTIVE: To evaluate the frequency of isolation of polio and other viruses from fecal samples in subjects with acute flaccid paralysis in northern parts of India. SETTING: Rural and Urban Immunization Centers used for Expanded Programme on Immunization. METHODS: 219 fecal samples were collected by anal tube in 1992 from Punjab, Haryana, Himachal Pradesh and Chandigarh and processed for virus isolation. RESULTS: Of 219 fecal samples, 103 (47%) were positive for viruses in the age group of 3 mo to 5 yr. Amongst the positive samples, the predominant isolated was poliovirus type 1 (70.9%) from all the States. Non polio enteroviruses were isolated from 20.4% of fecal samples. CONCLUSION: Even though poliovirus is still the most common etiologic agent for acute flaccid paralysis in northern India, non polio enteroviruses are also emerging as important causal pathogens in this condition.

Acute Disease↗
PubMed1995

Quantitation of protein content by biuret method during production of Yellow Fever Vaccine.

Protein content of 60 batches of Yellow Fever Vaccine was measured by Biuret method and was compared to the values obtained by Kjeldahl method. Statistical analysis did not show any difference between the two methods. The Biuret method is specific, easy to carry out and takes little time for protein estimation during production of Yellow Fever Vaccine.

Chemistry Techniques, Analytical↗
PubMed1995

A rapid test for measuring the infectivity of Yellow Fever vaccine.

An in-house reference preparation of 17D-204 Yellow Fever vaccine was tested 60 times using LD50 mouse assay and CCID50 method. The mean virus titre, standard deviation and coefficient of variation obtained were comparable. Student's t-test indicated that there was a statistically insignificant difference between the two methods (p > 0.05) used for potency test with a correlation coefficient of 0.666 (p < 0.05). CCID50 assay for measuring the infectivity of Yellow Fever vaccine is rapid, sensitive and reproducible.

Animals↗
PubMed1994

Factors affecting the sensitivity and reproducibility of passive haemagglutination test for the quantitation of measles-specific antibodies.

Various factors affecting the passive haemagglutination test (PHA) for the quantitation of measles-specific antibodies have been evaluated with the aim to obtain maximum sensitivity and reproducibility of the test. The antigen used for sensitization was prepared in Vero cells using Edmonston 245 strain of measles virus. Sheep red blood cells (SRBCs) were found most sensitive for use in PHA test. The optimum dilution of tannic acid was found to be 1:40,000 for tanning of fixed and 1:10,000 for unfixed SRBCs, when the tanning was carried out at 4 degrees C overnight. Fixed and tanned SRBCs sensitized with 32 HA units of measles HA antigen at 56 degrees C for 30 mins were found optimal. SRBCs from different sheep affected the sensitivity of the assay. Stability study of SRBCs showed that storage at -70 degrees C of glutaraldehyde-fixed and sensitized SRBCs gave better results as compared to those stored at -20 degrees C and +4 degrees C. Tanned SRBCs could be stored at -70 degrees C only up to 15 days. Sensitized SRBCs with-stood two cycles of freezing and thawing after removal from -20 degrees C and -70 degrees C. Sensitized SRBCs could be stored for 120 days without any significant loss of titer at -20 degrees C, +4 degrees C or 22 degrees C; when lyophilized with stabilizers, there was a slight decline in the titer after exposure at 37 degrees C for 30 days. The lyophilized sensitized SRBCs after reconstitution were found to be stable at +4 degrees C for 3 days without any loss in the titer.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Evaluation of potency of inactivated cholera vaccine by mouse protection assay & antibody induction method.

Twenty one batches of whole cell inactivated cholera vaccine manufactured at Central Research Institute, Kasauli were evaluated for potency by mouse protection assay (MPA) and antibody induction method. In the antibody induction method the sera of immunized mice were screened for the presence of antibodies against Vibrio cholerae by microagglutination (MA) test and IgG ELISA. The number of organisms estimated by MPA were correlated with agglutinating and neutralizing antibodies against individual serotypes by MA and ELISA respectively. Correlation coefficient(r) of 0.692 and 0.815 were observed for the titres evaluated by MA and ELISA when compared with standard MPA method for the serotype Ogawa. Similarly r values of 0.925 and 0.849 were observed for titres evaluated by MA and ELISA when compared with standard MPA method for the serotype Inaba. Antibody induction method can be as an alternative method for determining the potency of inactivated cholera vaccine.

Animals↗
PubMed1993

Study on the stability of 17D-204 yellow fever vaccine before and after stabilization.

To monitor the parameters controlling yellow fever vaccine production, eight different lots produced without stabilizers were studied. It was found that the freeze-thaw cycle did not have any adverse effect on virus infectivity and the mean loss in virus titre during lyophilization was 0.51 log10 ml-1. A thermodegradation study after storage of vaccine at different temperatures showed that the vaccine did not pass the accelerated stability test. To stabilize the 17D-204 substrain vaccine, four stabilizers with different sugars and amino acids were examined. The optimum time for addition of the stabilizers was found to be during homogenization of infected embryos. An accelerated stability test at 37 degrees C indicated that stabilizers S1, S2 and S3 kept the vaccine stable for up to 4 weeks, whereas the vaccine was only stable for up to 3 weeks in stabilizer S4. Stabilizer S3 was found statistically to be the best. Reproducibility in production methodology was established by preparing and testing more batches of the vaccine using stabilizer S3.

Animals↗