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Biomedical subjects

P K Menon

Publications and source records attributed to P K Menon.

At least 19 recordsLinked to original sources
PubMed2005

Polymerase chain reaction in rapid diagnosis of neonatal sepsis.

In a prospective study a total of hundred neonates who fulfilled the American College of Obstetrics and Gynecology's (ACOG) criteria for probable sepsis admitted to NICU of tertiary care armed forces hospital were investigated for evidence of sepsis. The investigation protocol included sepsis screen, blood culture and 1 mL of venous blood for molecular analysis by polymerase chain reaction (PCR) for bacterial DNA component encoding 16 s RNA in all cases. 100 newborns with probable sepsis were studied to evaluate the molecular diagnosis of sepsis using PCR amplification of 16 S RNA in newborns with risk factors for sepsis or those who have clinical evidence of sepsis. We compared the results of PCR with blood culture and other markers of sepsis screen (total leucocyte count (TLC), absolute neutrophil count (ANC), immature/total neutrophil count ratio (I/T ratio), peripheral blood smear, micro ESR and C reactive protein (CRP). Controls consisted of 30 normal healthy newborns with no overt evidence of sepsis. Sepsis screen was positive in 24 (24%) of cases in study group with sensitivity and specificity of 100% and 83.5% respectively. Blood culture was positive in 09(9%t) with sensitivity of 69.2% and specificity of 100%. PCR was positive in 13(13%) of cases (9% are both blood culture and sepsis screen positive and 4% are positive by sepsis screen); the sensitivity of PCR was 100% and specificity was 95.6%. Blood culture is the most reliable method for diagnosis of neonatal sepsis. Polymerase chain reaction is useful and superior to blood culture for early diagnosis of sepsis in neonates.

Bacterial Infections↗
PubMed2004

Phylogenetic conservation of the stem-loop III structure of the 5' untranslated region of Hepatitis C virus RNA among natural variants in samples collected from Southern India.

The stem-loop III (SLIII) structure within the 5' untranslated region has been shown to be critical for internal initiation of translation of Hepatitis C virus (HCV). Using 'Single Strand Conformation Polymorphism (SSCP)' of the SLIII region we have investigated for natural mutations and demonstrated presence of some non-covariant changes in certain sub-domains. However, overall SLIII-RNA structure was found to be phylogenetically conserved. Additionally, by SSCP analysis we have determined the genotype of 50 HCV isolates collected from Southern India, 25 random samples were confirmed by DNA sequencing. Results showed the prevalence of genotype 1 in this part of India.

5' Untranslated Regions↗
PubMed2001

Plasmid mediated antibiotic resistance in Klebsiella pneumoniae.

Klebsiella pneumoniae species (108) isolated from tertiary care hospitalized patients were investigated for antibiotic resistance patter. 74% isolates were from urine, 13.5% from pus, 4.5% from blood and 8% from sputum. The resistance pattern of the organisms to various antibiotics were as follows: ampicillin 93.3%, cefotaxime 70%, ceftazidime 81%, gentamicin 68.5%, amikacin 63.75%, netilmicin 74%, norfloxacin 55%, ofloxacin 53%, chloramphenicol 82%, tetracycline 85%, sulphamethoxazole 96%, trimethoprim 94%. 2-4 drug resistance was found in 34.5%, 5-8 drug resistance was in 25.1% and 9-12 drug resistance was found in 40.4% of strains. Out of 65 strains, 25 strains could be successfully conjugated. Common drugs which were transferred to transconjugants were sulphamethoxazole, trimethoprim, gentamicin, netilmicin, amikacin, chloramphenicol, tetracycline, ampicillin, cefotaxime and ceftazidime. A large plasmid of 98.7% kb could be demonstrated in these strains by alkali denaturation method and agarose gel electrophoresis.

Anti-Bacterial Agents↗
PubMed1994

Neonatal Salmonella havana meningitis.

The clinical features, microbial characterisation and autopsy findings in a premature neonate with Salmonellas havana meningitis is presented. S. havana is a very rare pathogen in India.

Fatal Outcome↗
PubMed1992

Assessment of multiple markers of environmental tobacco smoke (ETS) in controlled, steady-state atmospheres in a dynamic test chamber.

Controlled test atmospheres of sidestream and mixed mainstream/sidestream tobacco smoke were produced in a dynamic test chamber of 16.9 m3 volume. University of Kentucky 1R4F research cigarettes were automatically smoked by a Borgwaldt smoking machine. Different target levels of smoke were attained by varying the number of cigarettes being smoked (one or two cigarettes continuously) and dilution airflow through the chamber (1.6 to 7.4 m3/min). For each level, a "smoke index" was calculated as the number of cigarettes being smoked divided by the dilution flow rate. Ultraviolet light-absorbing particulate matter (UVPM); aerosol counts and size distribution; and concentrations of CO, NO2, NH3, formaldehyde, acetaldehyde, acrolein, and nicotine were determined in the test atmospheres and background dilution air. Parameters exhibiting the highest correlations with smoke index (r2 > 0.98) included UVPM, aerosol counts, formaldehyde, and acetaldehyde. The other parameters were also highly correlated with r2 > 0.9 in each case. Differences in concentration for sidestream and mixed mainstream/sidestream atmospheres were statistically significant for acetaldehyde, formaldehyde, and CO; in each case the level was higher in mixed mainstream/sidestream smoke. These results demonstrate the utility of employing multiple markers for assessment of environmental tobacco smoke levels and for dichotomizing the contributions of sidestream and mainstream smoke to these levels. The generation factors developed in this work can be used for estimating required ventilation rates for attainment of target air quality conditions in smoking rooms.

Air Pollutants↗
PubMed1991

Asthmatic responses to passive cigarette smoke: persistence of reactivity and effect of medications.

The present study assessed the persistence of cigarette-smoke reactivity and the effects of drug pretreatment on bronchial responsiveness to environmental tobacco smoke (ETS). Two groups of subjects were chosen for the study. Group I consisted of 15 atopic smoke-sensitive subjects with asthma, six of whom were defined "reactors" and nine "nonreactors" to ETS challenge. Group II consisted of 15 atopic subjects without asthma and with documented upper respiratory tract symptoms on exposure to ETS. All subjects were challenged for 2 to 6 hours with mechanically generated ETS in a static inhalation chamber. Five/six subjects in group I, who were previously demonstrated as reactors 24 months earlier, remained reactive within 1 to 2 hours of continuous ETS exposure. Pretreatment with albuterol, cromolyn, and a combination of albuterol and cromolyn 30 minutes before ETS exposure significantly diminished airway reactivity to ETS. All nine previous nonreactors in group I remained nonreactive despite rechallenge with ETS for up to 6 hours. Group II subjects challenged under identical conditions did not reveal a significant decline in FEV1 on challenge with ETS. These studies demonstrate the persistence of ETS reactivity during a 2-year period. Although cromolyn sodium and/or albuterol can protect against reactivity, mechanisms of ETS-induced airway reactivity remain unknown.

Adult↗
PubMed1991

Cockroach allergenic activity: analysis of commercial cockroach and dust extracts.

Previous investigations demonstrated that cockroach whole bodies and feces are important sources of allergens in the induction/exacerbation of bronchial asthma. The current study investigated different cockroach source materials, commercial extracts, and house dust extracts for cockroach allergenic activity. In general, extracts from four different sources of either American or German cockroaches contained similar amounts of allergenic activity by RAST inhibition. Three commercial American cockroach extracts compared by RAST inhibition had similar allergenic activity on an equal protein basis. Skin test results correlated house dust reactivity to both commercial and inhouse cockroach wholebody extracts and to fecal extracts. Six different samples of house dust obtained from vacuum cleaners in the New Orleans area and three commercially obtained house dust extracts contained varying quantities of cockroach allergenic activity by RAST inhibition. These studies demonstrate that commercial cockroach extracts vary in allergenic activity and that all house dust extracts tested contain cockroach allergens.

Allergens↗
PubMed1989

Epidemiology of bancroftian filariasis in a semi-urban community of Kerala State.

A community-based longitudinal study was initiated in 1983 in a semi-urban area, endemic for bancroftian filariasis to determine the incidence and prevalence, natural history and clinical pattern of filarial infection and also to study the impact of control measures on it. The base-line filariometric indices observed during the initial clinico-parasitological survey and entomological observations made during the first 12 months of this study are highlighted in this paper. 5.5 per cent of the examined population had microfilaraemia with average infestation of 8.1 per 20 cmm. The microfilaraemia found to have significant (P less than 0.001) relationship with age, but not with sex (P greater than 0.05). The filarial disease which had the prevalence of 3.6 per cent showed a significant (P less than 0.001) relationship to both age and sex. The youngest microfilaria (mf) carrier was of 2 years and with filarial swelling was of 6 years age. A significant (P less than 0.001) relationship of educational status and family size was observed with disease while it was non-significant (P greater than 0.05) with microfilaraemia. With the increase in per capita income of the individuals, a significant decrease in number of persons with microfilaraemia (P less than 0.01) as well as with disease (P less than 0.05) was noted. Culex quinquifasciatus, the vector for this infection was prevalent throughout the period of observation with highest density in September. Vector infection and infectivity rates ranged from 0 to 4.4 per cent and 0 to 2.2 per cent respectively.

Adolescent↗
PubMed1988

Cigarette smoke-sensitive asthma: challenge studies.

The effects of exposure to environmental tobacco smoke on pulmonary function were assessed in 21 subjects with asthma who claimed respiratory complaints (cough, shortness of breath, and chest tightness) on previous exposure to cigarette smoke. Exposure to mechanically produced tobacco smoke was performed in a static inhalation chamber for two-hour intervals at two distinct smoke levels (as measured by carbon monoxide, nicotine, and particulate levels). Seven of the 21 smoke-challenged subjects experienced a significant (greater than 20%) decline in FEV1 during passive exposure to tobacco smoke. One of these seven subjects was nonatopic, whereas a second subject had a negative response to methacholine challenge. The smoke-challenge responses were reproducible in all seven reactive subjects. Increasing concentrations of tobacco smoke failed to elicit pulmonary changes in previously challenged, unreactive or "smoke-tolerant" subjects. There was no association between a positive smoke challenge and the presence of serum IgE antibodies and/or a positive immediate wheal-and-flare skin test to a tobacco leaf extract. Collectively, these studies document a significant decline in pulmonary function in a substantial percentage (33%) of a population of "smoke-sensitive" subjects with asthma exposed to environmental tobacco smoke. The data also dissociate this effect from tobacco-leaf hypersensitivity.

Adult↗
PubMed1988

Duration of the suppressive effect of tricyclic antidepressants on histamine-induced wheal-and-flare reactions in human skin.

The antihistaminic properties of the tricyclic antidepressants have been recognized since these compounds were first developed. Antidepressants, which are equally effective for treating depression or used in the treatment of chronic urticaria, have varying in vitro antihistaminic properties. We compared the duration of H1-receptor blockade by two tricyclic antidepressants, doxepin (the most potent antihistamine) and desipramine (the least potent antihistamine), in a single dose, double-blind, noncrossover study. After baseline prick test with histamine phosphate 1:1000 by Multitest (Lincoln Diagnostics, Decatur, Ill.), the suppression of cutaneous histamine-induced wheal-and-flare responses were measured daily for 7 days in 33 healthy volunteers who were randomly administered a single 25 mg dose of oral desipramine or doxepin. Significant differences in the suppression of the wheal-and-flare responses to histamine between the two drugs were noted (p less than 0.05) during the first 3 days. Desipramine suppressed the wheal for 2 days and flare for 1 day. Doxepin suppressed the wheal for 4 days and flare for 6 days. Our results suggest doxepin should be withheld for at least 7 days before allergy skin testing.

Adult↗
PubMed1987

Laboratory study on the mosquito larvicidal properties of leaf and seed extract of the plant Agave americana.

Experiments on the leaf extract tested against three mosquito species led to 100% mortality of stage 4 Anopheles, Aedes and Culex larvae at a concentration of 0.08% within 24-48 h, whereas 100% mortality of stage 1 larvae occurred at lower concentrations: 0.0032% for Aedes aegypti, 0.016% for Culex quinquefasciatus and 0.08% for Anopheles stephensi, and was more rapid. At the end of 24 h, the highest dilution of the seed extract studied (1:200) produces a larval mortality of 100% for Anopheles and Aedes and 56% for Culex spp., when 4th instar larvae were exposed at room temperature. The comparative mortality in the control group was negligible. One hundred per cent mortality of Anopheles larvae took place by the end of 10 h, and of Aedes larvae by 17 h, at a dilution of 1:200 with water.

Aedes↗