A Clinical Study on the Circadian Rhythm of Salivary Cortisol on Aggressive Periodontitis and Its Correlation with Clinical Parameters using Electrochemiluminescence Immunoassay Method

AIM

Periodontal pathologies are gaining importance as there is a clear indication of bi-way control on general homeostasis of an individual. The study of HPA axis in various diseases has proved that there is evident vulnerability existing for any organism when the Cortisol diurnal rhythm is altered. The aim was to compare the diurnal rhythm of salivary cortisol in aggressive periodontitis with control patients. This study also compared various parameters like body mass index (BMI), waist circumference, Hamilton anxiety scale, OHI-S, clinical attachment loss in aggressive periodontitis.

MATERIALS AND METHODS

30 control patients were compared against 30 aggressive periodontitis patients in Salivary cortisol diurnal rhythm. It was estimated using the electrochemiluminescence (ECL) method on a 3 point analysis-Soon after waking up, 30 minutes after waking up, 1 hour before sleep to see the diurnal variation in aggressive periodontitis patients. The samples were transferred to CABRI labs to be frozen to -20°C. The analysis was done using Cobas e-411 autoanalyzer by Roche, USA.

RESULTS

The average cortisol in aggressive patients was found to be higher compared to control patients and was found to be statistically significant with a p value of 0.012. Control group is moderately skewed left (negative skewness graph) while the aggressive p periodontitis patients showed moderately skewed right (+ve skewness graph).

CONCLUSION

The cortisol awakening response seen in control patients is not observed in aggressive periodontitis. Instead of giving a surge, the cortisol showed a dip in the first 30 minutes followed by a gradual increase in aggressive periodontitis instead of decline as observed in normal patients.

CLINICAL SIGNIFICANCE

The study will focus on the importance of cortisol circadian rhythm on periodontal health allowing the microorganism to create an environment of dysbiosis.

Allelic variants of ADH, ALDH and the five factor model of personality in alcohol dependence syndrome

BACKGROUND

The etiology of alcohol dependence is a complex interplay of biopsychosocial factors. The genes for alcohol-metabolizing enzymes: Alcohol dehydrogenase (ADH2 and ADH3) and aldehyde dehydrogenase (ALDH2) exhibit functional polymorphisms. Vulnerability of alcohol dependence may also be in part due to heritable personality traits.

AIM

To determine whether any association exists between polymorphisms of ADH2, ADH3 and ALDH2 and alcohol dependence syndrome in a group of Asian Indians. In addition, the personality of these patients was assessed to identify traits predisposing to alcoholism.

MATERIALS AND METHODS

In this study, 100 consecutive males with alcohol dependence syndrome attending the psychiatric outpatient department of a tertiary care service hospital and an equal number of matched healthy controls were included with their consent. Blood samples of all the study cases and controls were collected and genotyped for the ADH2, ADH3 and ALDH2 loci. Personality was evaluated using the neuroticism, extraversion, openness (NEO) personality inventory and sensation seeking scale.

RESULTS

Allele frequencies of ADH2*2 (0.50), ADH3*1 (0.67) and ALSH2*2 (0.09) were significantly low in the alcohol dependent subjects. Personality traits of NEO personality inventory and sensation seeking were significantly higher when compared to controls.

CONCLUSIONS

The functional polymorphisms of genes coding for alcohol metabolizing enzymes and personality traits of NEO and sensation seeking may affect the propensity to develop dependence.

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.

Outbreak of Multi-drug Resistant Salmonella Typhi Enteric Fever in Mumbai Garrison

BACKGROUND

There was an epidemic of enteric fever in Mumbai garrison during Nov-Dec 2000 with more than 150 cases admitted to a tertiary care service hospital.

METHODS

All the cases presented with fever and some had splenomegaly, bradycardia, abdominal pain and diarrhoea. The epidemic was investigated by the station health organization (SHO) and the case and bacteriological study was carried out in pathology laboratory of the service hospital. The serological study was carried out at Armed Forces Medical College (AFMC), Pune and the Phage typing was carried out at Lady Harding Medical College, New Delhi.

RESULTS

Blood cultures were positive in 92(63%) for Salmonella typhi and Widal test was positive in 83(55%). All strains were resistant to four primary drugs i.e. ampicillin, chloramphenicol, co-trimoxazole and tetracycline. All but two were treated successfully with ceftriaxone. The Salmonella typhi belonged to phage group E1 and biotype I.

CONCLUSION

Extensive epidemiological investigation of cases and water sources of cantonment area pointed to a common source of the epidemic i.e. the well near 'Gurudwara'.

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.

Random Amplification of Polymorphic DNA Based Typing of Pseudomonas Aeruginosa

Pseudomonas aeruginosa was isolated from various sources during the course of an epidemic outbreak of bacterial endophthalmitis following an eye camp at Sangli, Maharashtra. 15 distinct isolates were obtained from clinical samples. Typing of the 15 isolates was performed by random amplified polymorphic DNA (RAPD) analysis, pyocin typing and antibiogram. RAPD typing was rapid, labour friendly and could be done within six hours. RAPD analysis produced reproducible electrophoretic band patterns on the basis of which three distinct amplification patterns could be visualised. The conventional typing methods were labour intensive and took about 48 hours. However, the results of RAPD typing, pyocin typing and antibiogram did not correlate with each other. This study suggests that RAPD typing could be an additional rapid typing method for studying the epidemiology of infectious disease outbreaks due to P aeruginosa.

A STRATEGY FOR RAPID IDENTIFICATION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS NASAL CARRIER STATUS

Methicillin Resistant Staphylococcus aureus (MRSA) is a multi drug resistant organism responsible for severe outbreaks of life threatening infections in hospitals which are difficult to treat They are spread by nasal carriage among the hospitalised patients, staff and visitors. Mannitol cloxacillin salt agar (MCSA) is a single tube method to identify MRSA. However, tubes showing growth and change in colour on biochemical characterisation often do not prove to be MRSA. In this study we have combined two strategies for the rapid identification and isolation of MRSA by culture in MCSA and multiplex PCR for mecA and femB genes. Anterior nasal swabs obtained from nursing staff and patients admitted to a large referral hospital, were inoculated into MCSA. Of the 100 tubes inoculated, 8 tubes showed change in colour and growth. On conventional testing 4 were MRSA, 3 were methicillin sensitive S aureus (MSSA) and 1 was Methicillin Sensitive Coagulase Negative S aureus (MSCNS). Genotyping by multiplex PCR revealed 5 MRSA, 2 MSSA and 1 MRCNS. The Multiplex PCR technique to rapidly identify presence of mecA and femB genes showed presence of both mecA and femB bands in all MRSA. The methicillin sensitive organisms showed absence of mecA gene while coagulase negative organisms showed absence of the fern B gene. Combining MSCA with multiplex PCR for mec A and fem B genes made the test both rapid and specific. Use of this strategy would enable rapid screening of nasal carriers and early implementation of hospital infection control measures.

HIV - 1 SUBTYPES, ITS IMPLICATIONS AND VIRAL DYNAMICS

Subtyping of HIV has important implications for developing candidate vaccine and understanding the biological behaviour and dynamics of HIV transmission in various populations. The third variable region (V3) in the envelope gene of HIV-1 has been shown to be a major determinant influencing a number of biological characteristics of the virus. HIV-1 evolves by rapid mutation and by recombination, both processes actively contributing to its genetic diversity. Most of the multiple genetic subtypes and intersubtype recombination of HIV-1 that comprise the global pandemic have not been characterized by full genome sequencing. The development of an effective human immunodeficiency virus type-1 (HIV-1) vaccine is likely to depend on knowledge of circulating variants of genes other than the commonly sequenced gag and env genes.

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.

COMPARISON OF RAPID METHOD OF DNA EXTRACTION USING MICROWAVE IRRADIATION WITH CONVENTIONAL PHENOL CHLOROFORM TECHNIQUE FOR USE IN MULTIPLEX PCR FOR mec A AND fem B GENES TO IDENTIFY GENOTYPES OF MRSA FROM CULTURES

Methicillin Resistant Staphylococcus aureus (MRSA) infection is a major cause of morbidity and mortality in hospitalised patients and requires vancomycin for effective therapy. Rapid identification of MRSA is vital to control MRSA outbreaks in hospitals. Identification of MRSA is a time consuming process requiring more than 48 hours and is labour intensive involving culture, biochemical tests and antimicrobial susceptibility testing. In this study we have used microwave irradiation of the bacterium obtained from cultures which was then directly subjected to a multiplex PCR technique to accurately and rapidly identify the presence of mec A and fem B genes which characterise MRSA. This has been compared with the standard method of lysing the bacterium and DNA extraction using phenol chloroform method followed by multiplex PCR. The microwave lysis method followed by direct PCR has been found to be less time consuming, 5 hours, as compared to 9 hours by conventional technique. Use of this strategy would enable early identification and early implementation of control measures.

RECENT ADVANCES IN TUBERCULOSIS DIAGNOSTIC TECHNIQUES

Tuberculosis is re-emerging as an important cause of morbidity and mortality in man. This article outlines current strategies available for the diagnosis of tuberculosis, and its applicability. Fluorescent staming, modified culture methods, antigen detection, ELISA based assays against various antigen preparation and recent advances in molecular techniques have been outlined. Present strategies being developed at Armed Forces Medical College for the early diagnosis, speciation, antibiotic sensitivity testing and epidemiologic testing have also been alluded to.

POLYMERASE CHAIN REACTION AND ADVANCES IN INFECTIOUS DISEASE DIAGNOSIS

The use of Polymerase Chain Reaction (PCR) in infectious disease diagnosis, has resulted in an ability to diagnose early and treat appropriately diseases due to fastidious pathogens, determine the antimicrobial susceptibility of slow growing organisms, and ascertain the quantum of infection. This article outlines the PCR, some of its modifications and their application in infectious disease diagnosis.

T HELPER SUBSETS AND INTERLEUKIN 12: ITS ROLE AS A POTENT IMMUNOMODULATOR OF CELL MEDIATED IMMUNITY

This article reviews Interleukin (IL) IL-12 a recently described cytokine secreted by monocyte/macrophages and its interaction with T cells. IL 12 is important in the immune response by providing a link between natural resistance mediated by phagocytic cells and NK cells and adaptive immunity mediated by T4, T8 and B cells. The article also evaluates the effect of IL12 in the evolution of T helper cell subsets, its action as a bridge between innate immunity and acquired immunity and the important role it plays in modulating the cellular and humoral immune response mechanisms. Its possible role as an immunomodulator of disease is postulated.

COMPLEMENT MEDIATED LYSIS, ADHESION, INVASION, AND MULTIPLICATION WITHIN HeLa CELLS AND HUMAN MONOCYTE MACROPHAGES OF SUSCEPTIBLE AND MULTIPLE DRUG-RESISTANT S. typhi

Twenty strains each of susceptible and multiple drug resistant strains of S. typhi were compared for susceptibility to complement lysis and cellular invasion. Drug resistant strains showed increased resistance to complement killing. Antibody increased the efficiency of complement killing of S. typhi. Susceptible and drug resistant strains showed almost the same rates of adherence and invasion of HeLa cells and human monocyte cell lines. However, the resistant strains showed a relatively higher rate of intracellular multiplication after 6 hours within human mononuclear macrophages. Decreased killing by complement and the relatively higher multiplication within mononuclear macrophages of the drug resistant strains may be the reason for their increased virulence.

SCANNING ELECTRON MICROSCOPIC STUDY OF HeLa CELL INVASION BY SALMONELLA TYPHI

Invasion of cultured non-pliagoeytic cells by salmonella is illustrated by a scanning electron microscopie study of HeLa cell invasion by S. typhi. This study shows that after bacterial adherence the HeLa cell cytoplasmic membrane shows ruffling and formation of filopodia which gradually engulf the bacterium and draw it into the cytoplasm. The available literature is reviewed and the probable mechanism underlying phagocytosis is hypothesized.

CLINICO-PATHOLOGICAL CORRELATION IN NEONATAL AUTOPSIES

Of the 253 neonates admitted to a neonate intensive care unit during the period Jan 91 to Sep 93, 43 neonates died. Autopsy was done in 23 of these (53%). The mean duration of stay of the neonates in the intensive care unit prior to death was 5.6 days (range 2 hours to 10 days). Antemortem diagnoses included asphyxia neonatorum (4), meconium aspiration syndrome (2), septicemia (5), prematurity (3), birth trauma (2), congenital anomalies (2), hypoxic ischemic encephalopathy (1), and non-specific diagnosis (4). There were 6 major autopsy findings that, if known prior to death, would have altered clinical management and might have resulted in cure or prolonged survival. There were 8 additional major findings that, if known prior to death, would not have altered management There were 14 minor findings related to major diagnoses but unrelated to the primary cause of death.

Postal follow up of patients with epilepsy

BACKGROUND

Epilepsy services in India are mostly located in urban areas and are often overcrowded. It is difficult, therefore, to organize long term management programmes. We report our experience at a tertiary referral centre on follow up of patients with epilepsy through regular postal review.

METHODS

One hundred consecutive patients with epilepsy (63 men, 37 women, mean age 17 years) who had only seizures were followed up by post using a questionnaire, instead of reviewing them in a clinic. The safety, utility and efficiency of this system were evaluated.

RESULTS

Sixty patients had generalized seizures, 30 had complex partial seizures and 10 had other types of seizures. The indication for shifting to postal review was good control of seizures in 87 cases and economic reasons in the remaining. Postal review constituted 60% of the total follow up period in 55 cases. Sixty-six patients could be maintained on postal review which was suspended or discontinued in 34 patients. Of these 34, 16 were returned to it after being seen in the clinic on a further occasion. Poor control of seizures, fresh medical or social problems, lack of confidence or a combination of these were the reasons for discontinuing the postal review. The economic benefit to a patient by way of savings in travel, incidental expenses and lost wages was estimated to be Rs 750 per annum. The work load in the epilepsy clinic was decreased by 40%. No serious medical problems or mortality were reported in the study population.

CONCLUSION

Systematic postal review is a cost-effective alternative to clinic review in the long term follow up of a certain group of patients with epilepsy.

STUDY OF SERUM AND BILE FROM PATIENTS OF CHOLELITHIASIS IN NORTH-EASTERN INDIA

Biochemical analysis of serum and bile from patients with cholelithiasis hailing form north-eastern India was done to provide pointers for lithogenicity. In comparison to controls, patients with cholelithiasis showed significant increase in serum phospholipid levels and lecithin cholesterol acyl transferase activity was significantly decreased. Enzymes like gamma glutamyl transferase, aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase showed a small though significant increase as compared to controls, suggesting evidence of subclinical hepatic dysfunction and probable evidence of relative bile stasis. Levels of cholesterol, lecithin and lecithin cholesterol acyl transferase activity were seen to be increased in gall bladder bile as compared to hepatic duct bile.

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.

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.

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.

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.

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.

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.

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.

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.