Quantitative analysis of gene amplification in insecticide-resistant Culex mosquitoes.

The amplification of carboxylesterase structural genes followed by their overexpression is the most common mechanism of resistance to organophosphorus insecticides in Culex mosquitoes. Most resistant Culex quinquefasciatus mosquitoes have co-amplified estalpha2(1) and estbeta2(1) genes. Recently, Southern, DNA dot-blot analysis and phosphorimaging technology were used to quantify the est gene copy number in aphids and mosquitoes. Although more accurate than autoradiography, this method relies on probe hybridization, which can be variable. We have directly measured gene and mRNA copy number by using real-time quantitative PCRs in mosquitoes. The acquisition of fluorescence from incorporation of the double-strand-specific dye SYBR GreenI into a PCR product once per cycle is used to provide an absolute quantification of the initial template copy number. Thus it has been possible to show that estalpha2(1) and estbeta2(1) are co-amplified approx. 80-fold in the genome of the resistant PelRR strain of C. quinquefasciatus. The two genes, although co-amplified in a 1:1 ratio, are differentially transcribed: the estbeta2(1) gene from this amplicon has greater transcription than estalpha2(1) in all individual mosquito larvae tested, with an average ratio of 10:1. Purified esterases from mosquito homogenates were found in a ratio of 3:1, which, combined with the quantitative mRNA data, suggests the operation of both transcriptional and translational control mechanisms to regulate the expression of the amplified genes in C. quinquefasciatus insecticide-resistant mosquitoes.

Psychosocial stress, physical symptoms, and anxiety in Greek students.

Specific stressor events may be a function of variables such as age, sex, marital status, and urban-rural differences. Psychosocial stress as measured by a Greek adaptation of the Schedule of Recent Experiences was studied in relation to physical symptoms, manifest anxiety, and social desirability in 138 Greek university students. Psychosocial stress was found to be related to physical symptoms and manifest anxiety only in females. The types of stressor events of the students were different from those of a sample of older Greek teachers. The implications of the findings for Greek culture are discussed.

Psychosocial stress, symptoms, and anxiety of male and female teachers in Greece.

Psychosocial stress as measured by a Greek adaptation of the Schedule of Recent Experiences (SRE) constructed by Holmes and Rahe was studied in relation to symptoms, manifest anxiety, visits to doctor, and health concerns using 129 male and female Greek elementary school teachers. Psychosocial stress was related to number of symptoms and to level of manifest anxiety only with women. Although no sex differences were found in average psychosocial ratings, males and females reported different stressful life events. Females reported more symptoms than males, and had higher manifest anxiety. Relationships of sex differences to cultural norms are discussed.

Psychosocial stress and its relation to obstetrical complications.

A Greek adaptation of the Schedule of Recent Experience of Holmes and Rahe was employed to study the relationship of psychosocial stress to symptoms during pregnancy, obstetric complications, family planning and breast feeding. An initial experiment with 130 pregnant women in the third trimester indicated that psychosocial stress was not related to education, whether they were from Athens or the provinces, nor age. The second experiment with 103 mothers 3 or 4 days after delivery indicated that high psychosocial stress is related to increased symptom scores during pregnancy and to obstetric complications. Symptoms were not related to obstetric complications, nor were family planning nor breast feeding. Psychosocial stress was also related to family planning and also to whether or not the mother breast fed.

PIP: The relationship between psychosocial stress, the occurrence of various symptoms during pregnancy, the occurrence of obstetric complications, family planning, and breast feeding intentions was assessed for 103 maternity patients at the Alexandra Maternity Hospital in Athens, Greece. A modified version of the Holmes and Rake Schedule of Recent Experience was used to measure the level of psychosocial stress. The modified instrument consisted of 48 stressogenic life events. Respondents were asked to identify the events they had experienced, to rate the level of stress induced by the event on a 0-100 scale, and to specify if the event occurred 0-6 months, 7-12 months, or 13-25 months prior to delivery. Respondents were also presented with a list of symptoms and asked to identify those they experienced during pregnancy, to rate the severity of the symptoms, and to identify the trimester in which they occurred. Subjective psychosocial stress scores and symptom scores were then calculated for each respondent. A gynecologist reviewed the delivery records of each woman and classified the delivery in respect to obstetric complications as either normal or abnormal. Respondents were also asked if the birth was the result of an unplanned or planned pregnancy and if they intended to breast feed their infant. Questionnaires were administered 3-4 days following delivery. Pearson product-moment correlation, analysis of variance, and chi-square techniques were used to analyze the data. The level of psychosocial stress experienced during the 6-month period prior to delivery was positively associated with the occurrence of obstetric complications; however, the level of stress experienced more than 6 months prior to delivery was not. The most common stressogenic events reported by women who had obstetric complications were 1) high anxiety about the health status of the fetus, 2) death of a loved one, 3) arguments with parents or spouse, 4) a sharp decline in income, and 5) job-related problems of spouse. The level of psychosocial stress was also positively related to occurrence of symptoms during pregnancy, and 25% of the variation in symptom scores was explained by differences in psychosocial stress levels. Symptom scores increased with each trimester of pregnancy, but were not associated with the occurrence of obstetric complications. Women who planned their pregnancies, in contrast to those who did not, had significantly lower psychosocial stress and symptom scores; however, the occurrence of obstetric complications was not significantly related to either planned or unplanned pregnancy. Similarly, women who intended to breast feed, compared with those who did not, had significantly lower psychoosocial stress and symptom scores, but breast feeding intention was not significantly related to the occurrence of obstetric complications. Women who planned to breast feed and women who planned their pregnancy tended to be younger than women who did not plan to breast feed and women who did not plan their pregnancy.