Free vibration analysis of all round clamped thin isotropic rectangular plate by Ritz Direct Variational Method

This paper developed polynomial comparison functions for the free vibration analysis of clamped thin rectangular plates using the Ritz Direct Variational Method. The polynomials were derived systematically from a predefined formula, which could generate any number of trial functions for any set of plate’s classical boundary conditions. The method was implemented by means of a Mathematica computer programme developed by the authors. The frequency parameters so obtained agreed excellently with those available in the literature. The numerical values of the frequency parameters increased with the aspect ratio irrespective of the mode considered. In addition, the study showed that the more the number of polynomial coordinate functions in the shape function, the better the accuracy of the results. The convergence study corroborated the fact that a one-term approximation yields sufficient accuracy. The convergence was best for square plates, even though acceptable percentages of convergence were obtained for the other side ratios.

[Umbilical Artery Doppler Study Role In The Monitoring And Obstetric Management Of High-Risk Pregnancies]

OBJECTIVE

to compare aspects of the diastolic component of umbilical artery flow with fetal fate parameters.

MATERIAL AND METHODS

this was a prospective, cross-sectional study at the Kaolack Regional Hospital over 6 months including patients with an at-risk pregnancy and a gestational age greater than 20 SA. The aspect of umbilical artery flow, umbilical artery IR and cerebro-placental index were studied.We compared the velocity data with the rates of fetal suffering, low birth weight and perinatal mortality. The statistical analysis was done with EPI info software version 7, Excel 2010 and SPSS 20.0 with a p-value of less than 5%.

RESULTS

46 patients were included with an average age of 24.54 years. The mean gestational age was 33.7 AS. The diastolic component of umbilical artery flow was null in 19.6%; reversed in 10.9%; decreased in 21.7% and normal in 47.8%. Confrontation with fetal fate parameters found a rate of 78.6% fetal suffering in the null or reversed diastolic components group compared to 34.4% in the non-zero diastolic components group. For low birth weight, this rate was 92.9% compared to 28.1%. The perinatal mortality rate was 64.2% compared to 12.5%.

CONCLUSION

The umbilical artery Doppler study plays a major role in the monitoring and obstetric management of high-risk pregnancies. Our results demonstrate the correlation between a diastolic component of the flow of the pathological umbilical artery and the adverse outcome of the pregnancy at risk.

Seasonal variation in spatial distributions of Anopheles gambiae in a Sahelian village: evidence for aestivation

Changes in spatial distribution of mosquitoes over time in a Sahelian village were studied to understand the sources of the mosquitoes during the dry season when no larval sites are found. At that time, the sources of Anopheles gambiae Giles may be local shelters used by aestivating mosquitoes or migrants from distant populations. The mosquito distribution was more aggregated during the dry season, when few houses had densities 7- to 24-fold higher than expected. The high-density houses during the dry season differed from those of the wet season. Most high-density houses during the dry season changed between years, yet their vicinity was rather stable. Scan statistics confirmed the presence of one or two adjacent hotspots in the dry season, usually found on one edge of the village. These hotspots shifted between the early and late dry season. During the wet season, the hotspots were relatively stable near the main larval site. The locations of the hotspots in the wet season and early and late dry season were similar between years. Season-specific, stable, and focal hotspots are inconsistent with the predictions based on the arrival of migrants from distant localities during the dry season, but are consistent with the predictions based on local shelters used by aestivating mosquitoes. Targeting hotspots in Sahelian villages for vector control may not be effective because the degree of aggregation is moderate, the hotspots are not easily predicted, and they are not the sources of the population. However, targeting the dry-season shelters may be highly cost-effective, once they can be identified and predicted.

Seasonal variation in metabolic rate, flight activity and body size of Anopheles gambiae in the Sahel

Malaria in Africa is vectored primarily by the Anopheles gambiae complex. Although the mechanisms of population persistence during the dry season are not yet known, targeting dry season mosquitoes could provide opportunities for vector control. In the Sahel, it appears likely that M-form A. gambiae survive by aestivation (entering a dormant state). To assess the role of eco-physiological changes associated with dry season survival, we measured body size, flight activity and metabolic rate of wild-caught mosquitoes throughout 1 year in a Sahelian locality, far from permanent water sources, and at a riparian location adjacent to the Niger River. We found significant seasonal variation in body size at both the Sahelian and riparian sites, although the magnitude of the variation was greater in the Sahel. For flight activity, significant seasonality was only observed in the Sahel, with increased flight activity in the wet season when compared with that just prior to and throughout the dry season. Whole-organism metabolic rate was affected by numerous biotic and abiotic factors, and a significant seasonal component was found at both locations. However, assay temperature accounted completely for seasonality at the riparian location, while significant seasonal variation remained after accounting for all measured variables in the Sahel. Interestingly, we did not find that mean metabolic rate was lowest during the dry season at either location, contrary to our expectation that mosquitoes would conserve energy and increase longevity by reducing metabolism during this time. These results indicate that mosquitoes may use mechanisms besides reduced metabolic rate to enable survival during the Sahelian dry season.

Dry season reproductive depression of Anopheles gambiae in the Sahel

The African malaria mosquito, Anopheles gambiae, is widespread south of the Sahara including in dry savannahs and semi-arid environments where no surface water exists for several months a year. Adults of the M form of An. gambiae persist through the long dry season, when no surface waters are available, by increasing their maximal survival from 4 weeks to 7 months. Dry season diapause (aestivation) presumably underlies this extended survival. Diapause in adult insects is intrinsically linked to depressed reproduction. To determine if reproduction of the Sahelian M form is depressed during the dry season, we assessed seasonal changes in oviposition, egg batch size, and egg development, as well as insemination rate and blood feeding in wild caught mosquitoes. Results from xeric Sahelian and riparian populations were compared. Oviposition response in the Sahelian M form dropped from 70% during the wet season to 20% during the dry season while the mean egg batch size among those that laid eggs fell from 173 to 101. Correspondingly, the fraction of females that exhibited gonotrophic dissociation increased over the dry season from 5% to 45%, while a similar fraction of the population retained developed eggs despite having access to water. This depression in reproduction the Sahelian M form was not caused by a reduced insemination rate. Seasonal variation in these reproductive parameters of the riparian M form population was less extreme and the duration of reproductive depression was shorter. Blood feeding responses did not change with the season in either population. Depressed reproduction during the dry season in the Sahelian M form of An. gambiae provides additional evidence for aestivation and illuminates the physiological processes involved. The differences between the Sahelian and riparian population suggest an adaptive cline in aestivation phenotypes between populations only 130 km apart.

Variation in metabolic rate of Anopheles gambiae and A. arabiensis in a Sahelian village

In the Sahel, the Anopheles gambiae complex consists of Anopheles arabiensis and the M and S molecular forms of A. gambiae sensu stricto. However, the composition of these malaria vectors varies spatially and temporally throughout the region and is thought to be linked to environmental factors such as rainfall, larval site characteristics and duration of the dry season. To examine possible physiological divergence between these taxa, we measured metabolic rates of mosquitoes during the wet season in a Sahelian village in Mali. To our knowledge, this study provides the first measurements of metabolic rates of A. gambiae and A. arabiensis in the field. The mean metabolic rate of A. arabiensis was higher than that of M-form A. gambiae when accounting for the effects of female gonotrophic status, temperature and flight activity. However, after accounting for their difference in body size, no significant difference in metabolic rate was found between these two species (whilst all other factors were found to be significant). Thus, body size may be a key character that has diverged in response to ecological differences between these two species. Alternatively, these species may display additional differences in metabolic rate only during the dry season. Overall, our results indicate that changes in behavior and feeding activity provide an effective mechanism for mosquitoes to reduce their metabolic rate, and provide insight into the possible strategies employed by aestivating individuals during the dry season. We hypothesize that female mosquitoes switch to sugar feeding while in dormancy because of elevated metabolism associated with blood digestion.

The contribution of aestivating mosquitoes to the persistence of Anopheles gambiae in the Sahel

Background

Persistence of African anophelines throughout the long dry season (4-8 months) when no surface waters are available remains one of the enduring mysteries of medical entomology. Recent studies demonstrated that aestivation (summer diapause) is one mechanism that allows the African malaria mosquito, Anopheles gambiae, to persist in the Sahel. However, migration from distant localities - where reproduction continues year-round - might also be involved.

Methods

To assess the contribution of aestivating adults to the buildup of populations in the subsequent wet season, two villages subjected to weekly pyrethrum sprays throughout the dry season were compared with two nearby villages, which were only monitored. If aestivating adults are the main source of the subsequent wet-season population, then the subsequent wet-season density in the treated villages will be lower than in the control villages. Moreover, since virtually only M-form An. gambiae are found during the dry season, the reduction should be specific to the M form, whereas no such difference is predicted for S-form An. gambiae or Anopheles arabiensis. On the other hand, if migrants arriving with the first rain are the main source, no differences between treated and control villages are expected across all members of the An. gambiae complex.

Results

The wet-season density of the M form in treated villages was 30% lower than that in the control (P < 10^-4, permutation test), whereas no significant differences were detected in the S form or An. arabiensis.

Conclusions

These results support the hypothesis that the M form persist in the arid Sahel primarily by aestivation, whereas the S form and An. arabiensis rely on migration from distant locations. Implications for malaria control are discussed.

Aestivation of the African malaria mosquito, Anopheles gambiae in the Sahel

The African malaria mosquito, Anopheles gambiae, inhabits diverse environments including dry savannas, where surface waters required for larval development are absent for 4–8 months per year. Under such conditions, An. gambiae virtually disappears. Whether populations survive the long dry season by aestivation (a dormant state promoting extended longevity during the summer) or are reestablished by migrants from distant locations where larval sites persist has remained an enigma for over 60 years. Resolving this question is important, because fragile dry season populations may be more susceptible to control. Here, we show unequivocally that An. gambiae aestivates based on a demographic study and a mark release–recapture experiment spanning the period from the end of one wet season to the beginning of the next. During the dry season, An. gambiae was barely detectable in Sahelian villages of Mali. Five days after the first rain, before a new generation of adults could be produced, mosquito abundance surged 10-fold, implying that most mosquitoes were concealed locally until the rain. Four days after the first rain, a marked female An. gambiae s.s. was recaptured. Initially captured, marked, and released at the end of the previous wet season, she has survived the 7-month-long dry season. These results provide evidence that An. gambiae persists throughout the dry season by aestivation and open new questions for mosquito and parasite research. Improved malaria control by targeting aestivating mosquitoes using existing or novel strategies may be possible.

Spatial swarm segregation and reproductive isolation between the molecular forms of Anopheles gambiae

Anopheles gambiae, the major malaria vector in Africa, can be divided into two subgroups based on genetic and ecological criteria. These two subgroups, termed the M and S molecular forms, are believed to be incipient species. Although they display differences in the ecological niches they occupy in the field, they are often sympatric and readily hybridize in the laboratory to produce viable and fertile offspring. Evidence for assortative mating in the field was recently reported, but the underlying mechanisms awaited discovery. We studied swarming behaviour of the molecular forms and investigated the role of swarm segregation in mediating assortative mating. Molecular identification of 1145 males collected from 68 swarms in Donéguébougou, Mali, over 2 years revealed a strict pattern of spatial segregation, resulting in almost exclusively monotypic swarms with respect to molecular form. We found evidence of clustering of swarms composed of individuals of a single molecular form within the village. Tethered M and S females were introduced into natural swarms of the M form to verify the existence of possible mate recognition operating within-swarm. Both M and S females were inseminated regardless of their form under these conditions, suggesting no within-mate recognition. We argue that our results provide evidence that swarm spatial segregation strongly contributes to reproductive isolation between the molecular forms in Mali. However this does not exclude the possibility of additional mate recognition operating across the range distribution of the forms. We discuss the importance of spatial segregation in the context of possible geographic variation in mechanisms of reproductive isolation.

Assessment of alternative mating strategies in Anopheles gambiae: Does mating occur indoors?

Mating in Anopheles gambiae has been observed only in outdoor swarms. Here we evaluate whether mating also occurs indoors. Mark-release-recapture of virgin males and females in natural houses showed that mating occurred over a single day even when mosquitoes can leave the house through exit traps and without adaptation to laboratory conditions. In these experiments, insemination rate in the M molecular form of An. gambiae (and An. arabiensis) was higher than that of the S form (15 versus 6%). Under these conditions, smaller females of the M form mated more frequently than larger females of that form. Sampling mosquitoes throughout the day showed that both sexes enter houses around sunrise and leave around sunset, staying indoors together from dawn to dusk. In an area dominated by the M form, the daily rate of insemination in samples from exit traps was approximately 5% higher than in those from entry traps, implying that mating occurred indoors. Importantly, frequency of cross mating between the molecular forms was as high as that between members of the same form, indicating that, indoors, assortative mating breaks down. Altogether, these results suggest that indoor mating is an alternative mating strategy of the M molecular form of An. gambiae. Because naturally occurring mating couples have not yet been observed indoors, this conclusion awaits validation.

Reproductive output of female Anopheles gambiae (Diptera: Culicidae): comparison of molecular forms

Knowledge of ecological differences between the molecular forms of Anopheles gambiae Giles (Diptera: Culicidae) might lead to understanding of their unique contribution to disease transmission, to better vector control, and to identification of the forces that have separated them. We compared female fecundity measured as egg batch size in relation to body size between the molecular forms in Mali and contrasted them with their sibling species, Anopheles arabiensis Patton. To determine whether eggs of different egg batches are of similar "quality," we compared the total protein content of first-stage larvae (L1s), collected < 2 h after hatching in deionized water. Egg batch size significantly varied between An. gambiae and An. arabiensis and between the molecular forms of An. gambiae (mean batch size was 186.3, 182.5, and 162.0 eggs in An. arabiensis and the M and the S molecular form of An. gambiae, respectively). After accommodating female body size, however, the difference in batch size was not significant. In the S molecular form, egg protein content was not correlated with egg batch size (r = -0.08, P > 0.7) nor with female body size (r = -0.18, P > 0.4), suggesting that females with more resources invest in more eggs rather than in higher quality eggs. The mean total protein in eggs of the M form (0.407 microg per L1) was 6% higher than that of the S form (0.384 microg per L1), indicating that the M form invests a greater portion of her resources into current (rather than future) reproduction. A greater investment per offspring coupled with larger egg batch size may reflect an adaptation of the M form to low productivity larval sites as independent evidence suggests.

The distribution of hatching time in Anopheles gambiae

Background

Knowledge of the ecological differences between the molecular forms of Anopheles gambiae and their sibling species, An. arabiensis might lead to understanding their unique contribution to disease transmission and to better vector control as well as to understanding the evolutionary forces that have separated them.

Methods

The distributions of hatching time of eggs of wild An. gambiae and An. arabiensis females were compared in different water types. Early and late hatchers of the S molecular form were compared with respect to their total protein content, sex ratio, development success, developmental time and adult body size.

Results

Overall, the distribution of hatching time was strongly skewed to the right, with 89% of the eggs hatching during the second and third day post oviposition, 10% hatching during the next four days and the remaining 1% hatching over the subsequent week. Slight, but significant differences were found between species and between the molecular forms in all water types. Differences in hatching time distribution were also found among water types (in each species and molecular form), suggesting that the eggs change their hatching time in response to chemical factors in the water. Early hatchers were similar to late hatchers except that they developed faster and produced smaller adults than late hatchers.

Conclusion

Differences in hatching time and speed of development among eggs of the same batch may be adaptive if catastrophic events such as larval site desiccation are not rare and the site's quality is unpredictable. The egg is not passive and its hatching time depends on water factors. Differences in hatching time between species and molecular forms were slight, probably reflecting that conditions in their larval sites are rather similar.

Adjuvant cytotoxic and endocrine therapy in pre- and postmenopausal patients with breast cancer and one to nine infiltrated nodes: five-year results of the Hellenic Cooperative Oncology Group randomized HE 10/92 study

SUMMARY

The present randomized phase III trial was designed to detect a 15% benefit in relapse-free survival (RFS) or overall survival (OS) from the incorporation of adjuvant tamoxifen to the combination of CNF [cyclophosphamide, 500 mg/m2; mitoxantrone (Novantrone), 10 mg/m2; fluorouracil, 500 mg/m2 chemotherapy and ovarian ablation in premenopausal patients with node-positive breast cancer and conversely from the incorporation of CNF chemotherapy to adjuvant tamoxifen in node-positive postmenopausal patients. From April 1992 until March 1998, 456 patients with operable breast cancer and one to nine infiltrated axillary nodes entered the study. Premenopausal patients were treated with six cycles of CNF chemotherapy followed by ovarian ablation with monthly injections of triptoreline 3.75 mg for 1 year (Group A, 84 patients) or the same treatment followed by 5 years of tamoxifen (Group B, 92 patients). Postmenopausal patients received 5 years of tamoxifen (Group C, 145 patients) or 6 cycles of CNF followed by 5 years of tamoxifen (Group D, 135 patients). Adjuvant radiation was administered to all patients with partial mastectomy. After a median follow-up period of 5 years, 125 patients (27%) relapsed and 79 (17%) died. The 5-year actuarial RFS for premenopausal patients was 65% in Group A and 68% in Group B (p = 0.86) and for postmenopausal patients 70% in Group C and 67% in Group D (p = 0.36). Also, the respective OS rates were 77% and 80% (p = 0.68) for premenopausal and 84% and 78% (p = 0.10) for postmenopausal patients. Severe toxicities were infrequently seen, with the exception of leukopenia (18%), among the 311 patients treated with CNF. In conclusion, the present study failed to demonstrate a 15% difference in RFS in favor of node-positive premenopausal patients treated with an additional 5 years of tamoxifen after CNF adjuvant chemotherapy and ovarian ablation. Similarly, six cycles of CNF preceding 5 years of tamoxifen did not translate to a 15% RFS benefit in node-positive postmenopausal patients.

Correlation between morphology, immunohistochemistry and molecular pathology in hereditary and sporadic breast cancer cases

Breast cancer still represents a serious health problem and is currently the most frequent malignancy in the female population in developed countries. In Cyprus, there are 300 new cases annually. In the present study, histology, electron microscopy, immunohistochemistry, and Western blot analysis were used to investigate 100 cases of invasive breast carcinoma. In addition, mutation analysis for the BRCA1 gene was carried out in patient DNA from 26 families with multiple cases of breast/ovarian cancers. Of note are the results of molecular biology which show that there are no germline truncating mutations in the BRCA1 gene in these 26 Cypriot breast cancer families. Furthermore, Western blot analysis revealed the presence of multiple BRCA1 bands in homogenates of tumor and normal tissues, and immunoelectron microscopy showed the presence of nuclear staining for BRCA1 antibodies.

Weekly paclitaxel as first-line chemotherapy and trastuzumab in patients with advanced breast cancer. A Hellenic Cooperative Oncology Group phase II study

AIM

To evaluate the activity and acute toxicity of the combination of weekly paclitaxel as first-line chemotherapy and trastuzumab, in patients with HER-2/neu overexpressing advanced breast cancer (ABC).

BACKGROUND

Weekly paclitaxel has been shown to be a well tolerated treatment with considerable activity in patients with ABC. Clinical trials with transtuzumab, a humanized anti-p185 HER-2/neu monoclonal antibody have demonstrated that this agent produces objective responses in patients with ABC.

PATIENTS AND METHODS

From December 1998 to April 2000, 34 patients with HER-2/neu overexpressing ABC were treated with weekly paclitaxel; given by one-hour infusion at a dose of 90 mg/m2 immediately followed by trastuzumab, 4 mg/kg as a loading dose and 2 mg/kg i.v. given over 30 min, thereafter weekly for at least 12 weeks. Expression of HER-2/neu was determined by immunohistochemical analysis on fixed, paraffin-embedded tissues. Eligible patients were required to have > or = 25% stained tumor cells.

RESULTS

Thirty-three patients completed at least 12 weeks of combined treatment. After completion of the 12th week of treatment, four patients (12%) achieved complete and 17 (50%) partial response. Median duration of response was 11.6 months. More frequent side effects included anemia (56%). neutropenia (27%), peripheral neuropathy (78%), diarrhea (30%), alopecia (70%), arthralgias/myalgias (62%), fatigue (59%) and hypersensitivity reactions (62%). Median time to progression was nine months while median survival had not been reached

CONCLUSIONS

The combination of weekly paclitaxel and trastuzumab is a safe and active regimen for patients with HER-2/neu overexpressing ABC. Randomized phase III studies with this combination are warranted.

BRCA1 germline mutations in Cypriot breast cancer patients from 26 families with family history

Germline mutations in the BRCA1 gene are causative for a variable number of hereditary breast/ovarian cancers. The data presented in this study are based on genetic analysis of the BRCA1 gene in 49 DNA samples from breast cancer patients with a positive family history. A combination of manual direct DNA sequencing and SSCP analysis was used to screen the entire coding region of BRCA1. Overall 13 variants were detected which included 5 missense mutations, 3 polymorphisms and 5 intronic changes. Further genetic analysis of the 13 variants was carried out using 50 control DNA samples. Our results showed that 12 out of the 13 variants detected in the DNA of the patients group, were also present in the control group. It appears that the Greek Cypriot families studied so far have an unexpectebly low frequency of deleterious mutations in the BRCA1 gene. This is the first report on BRCA1 mutation analysis in Cyprus.

Immunohistochemical versus molecular detection of RAK antigens in breast cancer

RAK antigens p120, p42, and p25 exhibit molecular and immunological similarity to the proteins encoded by HIV-1 and are expressed by 95% of breast and gynecological cancer cases in women and prostate cancer cases in men. Binding of the monoclonal antibody (MAb) RAK-BrI to cancer RAK antigens has been found to be inhibited by a peptide derived from the variable loop V3 of HIV-1. Since MAb RAK-BrI has been developed against denatured froms of breast cancer proteins, and it binds to a short epitope, GRAF, this MAb does not recognize the native, three-dimensional structure of proteins. Subsequently Western blot, after electrophoretic separation in gels with SDS, has been used to detect these unique cancer markers. The current studies were focused on the immunohistochemical evaluation of the novel marker RAK. Serial sections, 5 microm thick, were cut from frozen or Formalin-fixed, paraffin-embedded tissue blocks and immunostained with MAb RAK-BrI. All of the 53 cases of breast cancer tested RAK positive and no differences were observed in the immunohistochemical staining of lobular and ductal carcinoma cases. In contrast, MAb RAK-BrI antigens were detected in only 3 of 15 cases of macroscopically normal breast removed during mastectomy for breast cancer. It is noteworthy that Western blots of breast samples from the same series demonstrated a high expression of three RAK antigens in 20/20 of invasive breast carcinomas, while there was only a very weak expression of RAK antigens in 2/7 of the macroscopically "normal" breast samples. Due to the suspected viral origin of RAK markers, immunohistochemical staining with MAb RAK-BrI might be a useful tool in the early detection of malignant changes occurring in breast tissues.

Prognostic variables in greek patients with stage II breast cancer: a Hellenic Cooperative Oncology Group study

The independent effects of several patient, tumor and treatment-related prognostic factors on relapse-free survival (RFS) and overall survival (OS) were assessed by Cox multivariate regression analysis in 988 Greek patients with stage II breast cancer. At a median follow-up time of 83 (range 3.3-131+) months and after the evaluation of all patients together, the number of positive axillary nodes (p < 0.0001), tumor size (p = 0.0024) and tumor grade (p = 0.0008) were identified as significant prognostic factors for RFS. Also, the number of positive nodes (p < 0.0001), tumor size (p = 0.0002) and ER status (p = 0.0001) were found to be significant for OS. These short-term prognostic variables are similar to those reported for this group of patients in other European countries and in the USA.

[Epidemiological notes: meningococcal meningitis of serogroup X in Niamey (Niger)]

From 19th February to 15th April 1990, 22 strains of meningococcus belonging to serogroup X have been identified by the Centre for Study and Research on meningitidis and Schistosomiases (CERMES) at Niamey (Niger). Serogroup X has been confirmed by the Centre Collaborating WHO of Reference and Training for Meningococci (CCOMSRFM) at Marseille (France). These strains have been isolated from cerebrospinal fluid of patients suffering from cerebrospinal meningitis and living in different neighbourhoods of Niamey. Apparition of cases of meningococcal meningitis with other serogroups than A implies identification of serogroup of meningococcus in intertropical Africa.