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Biomedical subjects

H N Madhavan

Publications and source records attributed to H N Madhavan.

At least 19 recordsLinked to original sources
PubMed1998

Development and use of nested polymerase chain reaction (PCR) for the detection of adenovirus from conjunctivitis specimens.

BACKGROUND: The standard virus isolation method for detecting adenovirus is time consuming and direct detection of viral antigens in smears has its limitations. Therefore a rapid and a reliable method to identify virus in clinical specimens is desirable. OBJECTIVE: To develop and evaluate nested PCR as a tool for detecting adenovirus from conjunctival swabs of patients with acute conjunctivitis during an epidemic. STUDY DESIGN: A total of 201 patients with acute conjunctivitis were seen between August and November 1996. Conjunctival swabs from the most recently affected eyes were collected from 20 random patients and processed for antigen detection in direct smears, for adenovirus, enterovirus (EV70) and coxsackievirus A24 variant and adenovirus isolation by culture. Nested PCR was performed using oligonucleotides to amplify 1004 basepair (bp) and 956 bp fragments of DNA coding for adenovirus hexon protein. The neutralisation test, to type the adenovirus, was done on four isolates selected at random. RESULTS: The PCR could detect 0.0032 fg of adenovirus DNA (corresponding to 8.3 x 10(-3) adenovirus particles). The EV70 and coxsackievirus A24 antigens were not detected. The specimens were positive for adenovirus by all three techniques in seven patients: (a) by direct smear and PCR in 2; (b) by virus isolation and PCR in 2; and (c) by PCR alone in five patients. In one patient the direct smear alone was positive. The PCR required 3 days to detect the virus, antigen detection provided diagnosis the same day and virus isolation required 8-27 days. A total of four isolates selected at random were identified as serotype 7a. CONCLUSION: The nested PCR is a reliable and rapid technique for detection of adenovirus from conjunctival swabs. The adenovirus serotype 7a was the likely causative agent of this epidemic conjunctivitis.

Acute Disease↗
PubMed1998

Polymerase chain reaction in the diagnosis of bacterial endophthalmitis.

BACKGROUND: Microbiological investigations of vitreous fluid (VF) and aqueous humour (AH) specimens have often failed to detect the infecting agent in infectious endophthalmitis, resulting in a clinical dilemma regarding therapy. In this study, the polymerase chain reaction (PCR) was evaluated in the diagnosis of bacterial and Propionibacterium acnes endophthalmitis. METHODS: 58 intraocular specimens (30 VF and 28 AH) from 55 cases of endophthalmitis and 20 specimens (14 VF and 6 AH) as controls from non-infective disorders were processed for microbiological investigations. Nested PCR directed at the 16S rDNA using universal primers for eubacterial genome was done. PCR for P acnes was performed on specimens microbiologically negative by conventional techniques but eubacterial genome positive. RESULTS: Of the 20 controls from non-infective cases, one (5%) was positive using eubacterial primers and none with P acnes primers. PCR for eubacterial genome showed 100% correlation with 20 (34.5%) bacteriologically positive specimens. Eubacterial genome, was detected in 17 (44.7%) of 38 bacteriologically negative specimens and nine (52.9%) out of the 17 were positive for P acnes genome. Among the 21 eubacterial PCR negative specimens, seven were fungus positive. By inclusion of PCR, microbiologically positive specimens increased from 46.5% to 75.8%. PCR on AH was as sensitive as that on VF for the detection of both eubacterial and the P acnes genome. CONCLUSION: PCR performed on AH and VF is a reliable tool for the diagnosis of bacterial and P acnes endophthalmitis particularly in smear and culture negative specimens.

Aqueous Humor↗
PubMed1998

Effects of viscoelastic ophthalmic solutions on cell cultures.

The development of mild but significant inflammation probably attributable to viscoelastic ophthalmic solutions in cataract surgery was recently brought to the notice of the authors, and hence a study of the effects of these solutions available in India, on cell cultures was undertaken. We studied the effects of 6 viscoelastic ophthalmic solutions (2 sodium hyaluronate designated as A and B, and 4 hydroxypropylmethylcellulose designated as C, D, E and F) on HeLa, Vero and BHK-21 cell lines in tissue culture microtitre plates using undiluted, 1:10 and 1:100 dilutions of the solutions, and in cover slip cultures using undiluted solutions. Phase contrast microscopic examination of the solutions was also done to determine the presence of floating particles. The products D and F produced cytotoxic changes in HeLa cell line and these products also showed the presence of floating particles under phase contrast microscopy. Other products did not have any adverse effects on the cell lines nor did they show floating particles. The viscoelastic ophthalmic pharmaceutical products designated D and F have cytotoxic effects on HeLa cell line which appears to be a useful cell line for testing these products for their toxicity. The presence of particulate materials in products D and F indicates that the methods used for purification of the solution are not effective.

Animals↗
PubMed1998

Microbiological assay of ampicillin in serum and aqueous humor of patients given ampicillin-sulbactam injection.

The aim of this study was to determine the bacterial growth inhibitory activities of ampicillin in aqueous humor and serum of patients administered ampicillin-sulbactam combination intramuscularly prior to cataract surgery. 43 patients received a combination of both antibiotics intramuscularly at varying periods (60-140 minutes) prior to surgery. Aqueous humor and venous blood were collected at the beginning of the surgery. For microbiological assay, spores of Bacillus subtilis were incorporated in the agar. The test sample and the standard solutions (calibrators) of ampicillin and ampicillin-sulbactam combination were placed in 3 mm wells in the agar. The diameter zones of growth inhibitory activities of ampicillin of the calibrators and the test samples measured in mm were extrapolated to the standard curve and were recorded as ampicillin activity in micrograms/ml. The results of the assay were placed in 5 groups according to the time intervals between injection and collection of serum and aqueous humor (< or = 70, 75, 80, 90, > 90 minutes). Ampicillin activities in sera and aqueous humor of group 5 (> 90 minutes) were significantly higher than the others (p < 0.001). The ratio of ampicillin activities of sera and aqueous humor in group 5 patients was significantly lower indicating higher concentration of ampicillin activity in aqueous humor during this period. Bacterial growth inhibitory activities of ampicillin-sulbactam combination were adequate in aqueous humor of all patients with highest activity being 90 minutes after intramuscular administration indicating the potential usefulness of this antibiotic combination as chemoprophylaxis prior to cataract surgery.

Adult↗
PubMed1997

First report of congenital or infantile cataract in deranged proteoglycan metabolism with released xylose.

AIM: To investigate the chemical pathology in the blood and lens, in cases of congenital or infantile cataract in children excreting predominantly non-reducing carbohydrates in urine. METHODS: Urine samples from children with congenital or infantile cataract, and age and sex-matched controls, were analysed for (i) inherited errors of metabolism, (ii) paper chromatography of sugars, (iii) spectrophotometric assay of glycosaminoglycans (GAG), (iv) cetyl trimethyl ammonium bromide test, (v) electrophoresis using Alcian blue, (vi) ion exchange chromatography with IR 120 resin, and (vii) HPLC for xylose. Blood and lens material were also tested for GAG fragments and xylose. beta Glucuronidase was assayed in lymphocytes and urine. RESULTS: Of 220 children of both sexes below 12 years of age, with congenital or infantile cataract treated in Sankara Nethralaya, Madras, India, during a period of 2 years, 145 excreted fragments of GAG (heparan and chondroitin sulphates) in their urine. There was no such excretion among the control group of 50 children. The same was found accumulated in the blood and lenses of affected children. In addition, xylose was present in small amounts in the urine and blood and xylitol was present in the lens. There was a significant elevation in the activity of beta glucuronidase in lymphocytes and urine, when compared with normals. All the above findings suggest deranged proteoglycan metabolism. As the urine contained mostly GAG fragments and very little xylose, Benedict's reagent was not reduced. This ruled out galactosaemia. CONCLUSION: An increase of beta glucuronidase activity might have caused extensive fragmentation of GAG with resultant accumulation in the blood and lens and excretion in urine. Small amounts of xylose may have come from xylose links between GAG and core protein of proteoglycans. Owing to their polyanionic nature, GAG fragments in the lens might abstract sodium, and with it water, thereby increasing the hydration of the lens. Excessive hydration and the osmotic effect of xylitol from xylose might cause cataract. While corneal clouding has been reported in inborn acid mucopolysaccharidosis, congenital or infantile cataract with deranged metabolism of proteoglycans (acid mucopolysaccharide-xylose-protein complex) is reported in children for the first time.

Case-Control Studies↗
PubMed1997

In vitro effects of mitomycin C on human Tenon's capsule fibroblasts & correlation with surgical outcome in glaucoma patients.

The effects of mitomycin C (MMC, 1 microgram/ml for 5 min) on growth and morphology of six MMC 'sensitive' and four MMC 'resistant' human Tenon's capsule fibroblasts grown from 10 patients who had had trabeculectomy for glaucoma were studied. The surgical outcome of trabeculectomy in these patients were evaluated at the end of 8-10 wk. Both types of fibroblasts showed increase of growth up to 7 days. MMC 'sensitive' fibroblasts degenerated and declined to insignificant numbers in 47 days. MMC 'resistant' fibroblasts after a decline in growth up to 27 days showed remarkable recovery in morphology and growth by day 37. Surgical outcome positively correlated with in vitro results of 'sensitive' fibroblasts. A few clones of MMC 'resistant' fibroblasts survived and multiplied as MMC effect had worn off.

Antibiotics, Antineoplastic↗
PubMed1997

Serological evidence for active Epstein-Barr virus infection in multifocal choroiditis.

Six patients, consisting of 4 males and 2 females with mean average age fo 29.20 years, with variable picture of multifocal choroiditis were serologically investigated for their association with Epstein-Barr Virus (EBV) infection. IgG and IgM antibodies to EBV-Virus Capsid Antigen (VCA) were assayed by immunoperoxidase method on EBV infected lymphoblast cells (P3HR-1 Burkitt's lymphoma cell line). In these patients definite serological evidence of EBV infection with high titres of IgG and IgM antibodies to EBV-VCA was demonstrated suggestive of active continuing or persisting EBV infection.

Adult↗
PubMed1997

Evaluation of lymphocyte proliferation assay to purified protein derivative, enzyme linked immunosorbant assay, and tuberculin hypersensitivity in Eales' disease.

The purpose of this study was to evaluate the immunological responses against mycobacterial antigens in Eales' disease. Fifty six patients with Eales' disease and fifty age-and-sex-matched healthy volunteers with normal fundus findings taken as controls, were subjected to Mantoux test, using 2 TU/0.1 ml of purified protein derivative (PPD), lymphocyte proliferation assay to PPD, and ELISA to detect IgM and IgG antibodies against mycobacterial A-60 antigen. The results of Mantoux test and lymphocytes proliferation assay did not differ significantly in the two groups suggesting a similar cellular immune response. The number of individuals with recent exposure/reexposure to tuberculosis (IgM+) was significantly higher among patients. However the number of people with past exposure (IgM-IgG+) was significantly higher among controls. Our study indicates that there are no statistically significant differences in the humoral and cellular immune responses to mycobacterial antigens between the patients with Eales' disease and controls, except for a significantly higher IgM positivity among the patients.

Adolescent↗
PubMed1996

Co-occurring adenoviral keratitis and hemorrhagic cystitis. A case report.

Adenoviruses are ubiquitous viruses, commonly causing ocular infections. They are also known to cause multisystem infections. External ocular infections caused by adenovirus are most often due to contaminated secretions. We report a patient in whom genitourinary symptoms developed and subsided along with ocular symptoms. Adenovirus was isolated on ocular culture. This is the first reported case of concurrent adenoviral keratitis and hemorrhagic cystitis. Eliciting a history of genitourinary and respiratory symptoms is important in patients with ocular adenoviral infections.

Adenoviridae Infections↗
PubMed1996

Isolation and characterisation of nocardia from clinical specimens.

Sixteen isolations of nocardia of which 12 were from pulmonary infections, one from wound infection, one from mycetoma and 2 from eye infections were studied from June, 1989 to May, 1990. The importance of Gram's stain findings of primary smear is being highlighted. The nocardia species were identified utilising the morphological characters including acid fastness and cultural and biochemical characters. Notable among the isolates were Nocardia brasiliensis, one each from mycetoma and pulmonary infection, which are rare in South India and Nocardia asteroides from a case of endophthalmitis probably of endogenous origin.

Aged↗
PubMed1996

Ocular chlamydial infections. Clinicomicrobiological correlation.

We report the results of conjunctival scrapings done in 234 eyes of 127 patients presenting with acute, chronic, or recurrent conjunctivitis. Although some patients had the classic features of superior pannus, Herbert's pits, conjunctival follicles, and tarsal distortions, others presented in a more subtle fashion mimicking allergic, viral, and bacterial diseases of the eyes. These scrapings were subjected to rapid diagnostic techniques and culture studies for the identification of chlamydial infections. The correlation between the clinical and laboratory diagnosis was studied. Of the 127 patients, 44 were culture positive for Chlamydia. Of these, only 19 had been clinically suspected to have chlamydial ocular disease, whereas the others were diagnosed to have bacterial, viral, allergic, or other diseases. This higher rate of Chlamydia detection is probably a reflection of endemicity of this infection in India. This article highlights the possible underdiagnosis of chlamydial ocular disease in the outpatient department and emphasizes the importance of microbiological evaluation in patients with atypical or chronic ocular surface disease.

Adult↗
PubMed1996

In vitro activities of tetracycline & ciprofloxacin against Chlamydia trachomatis isolates from conjunctivitis patients.

Twenty seven Chlamydia trachomatis isolates from patients of conjunctivitis were tested for their in vitro sensitivities to ciprofloxacin and tetracycline in cyclohexamide treated McCoy cells on cover slip (shell vial) cultures. After a 48 h exposure of chlamydia infected monolayers to varying concentrations of each of the drugs, the cover slips were processed and stained for detection of major out membrane protein of C. trachomatis by fluorescent antibody test (FAT) using fluorescein conjugated monoclonal. Minimum inhibitory concentration (MIC90) and minimum lethal concentration (MLC90) of ciprofloxacin were 2.9 micrograms/ml and 5.7 micrograms/ml and for tetracycline 9.1 micrograms/ml and 18.0 micrograms/ml respectively. Ciprofloxacin may have a more promising role in treating chlamydial conjunctivitis than the commonly used tetracycline.

Anti-Bacterial Agents↗
PubMed1995

Investigations in the virological etiology in acute retinal inflammation.

Virological investigations for herpes simplex virus (HSV), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) were performed in nine patients of acute retinal inflammation. Serum samples of all the patients were assayed for IgG and IgM antibodies to HSV, CMV and EBV. Vitreous fluid (VF) from 5 patients was tested by immunofluorescence and culture for detection of HSV and CMV. In four patients, VF was also assayed for IgG and IgM antibodies to HSV and CMV. HSV was shown to be the etiological agent in 3 patients with acute retinal necrosis (ARN) syndrome and in one patient with multifocal retinitis. CMV was the causative agent in one patient of ARN and 1 patient with clinically diagnosed CMV retinitis. Evidences of infection with these three viral agents could not be obtained in one patient with clinical diagnosis of CMV retinitis who tested positive for antibody to human immunodeficiency virus 1. All other patients were HIV negative. Identification of the causative viral agent of acute retinal inflammations may help an ophthalmologist to institute specific therapy particularly for HSV and CMV infections.

Acute Disease↗