Probabilistic estimation of the source component of seismic hazard in North-Eastern Brazil.

Stable continental regions pose unique challenges for conducting Probabilistic Seismic Hazard Analysis because the earthquake activity driving mechanisms are poorly understood. For instance, the lower seismicity (hence the paucity of data) and the absence of well-defined active fault systems complicate accurately determining seismic source parameters. Northeastern Brazil is a stable continental region exhibiting moderate-size events recorded with significant seismic intensities and provoking the collapse of poorly constructed buildings in the last century. Thus, assessing the seismic hazard is critical for seismic risk mitigation. The seismic hazard depends on three components: source, path, and site, and here, we present the probabilistic seismic hazard analysis of the source component for NE Brazil. Spatial aggregation of earthquake sources outlined four areal seismic zones. A goodness-of-fit test rejected the Gutenberg-Richter model of magnitude frequency distribution in one of the studied seismic zones. For this reason, we estimated the magnitude probability distribution function in that zone using a nonparametric adaptive kernel estimator. In other zones the Gutenberg-Richter magnitude frequency model was applied. In either way of the magnitude probability distribution modelling we considered the upper bound for magnitude equal to 6.6 mR, based on the upper bound of a 95 % confidence interval for the standard normal distribution of palaeoearthquake sizes. Our findings suggests that potentially damaging events are likely to occur, and we cannot neglect chances for the occurrence of earthquakes exceeding 5.2 mR. The calculated mean return periods indicate significantly shorter intervals between consecutive large events than palaeoseismic records.

Dental anomalies in primary dentition and their corresponding permanent teeth.

OBJECTIVES: The objectives of this paper are to estimate the prevalence of dental anomalies in primary dentition in a sample of 2- to 5-year-old Brazilian preschool children, determine their distribution, and investigate their occurrence in the succedaneous teeth of the sample compared with a control group of children with no dental anomalies in the primary dentition. MATERIALS AND METHODS: The one-stage sample comprised 1,718 two to five-year-old children with fully erupted primary dentition clinically examined for dental anomalies. All children presenting dental anomalies underwent panoramic radiographs. Descriptive statistics were performed for the studied variables. A control group matched by sex and age was studied to compare the prevalence ratio for dental anomalies in the permanent dentition. RESULTS: The prevalence of dental anomalies in the primary dentition was 1.8 %, with no significant statistical difference between sexes. Double teeth were the most frequently observed. Dental anomalies on the succedaneous permanent teeth were diagnosed in 54.8 % of the children with affected primary dentition. The prevalence ratio (PR) for dental anomalies in the succedaneous permanent teeth was 17.1 (confidence interval (CI) 5.33-54.12) higher compared with the control group, higher in children with bilateral anomalies (PR = 31.2, CI 10.18-94.36). CONCLUSIONS: An association between anomalies of the permanent dentition and the presence of dental anomalies in primary teeth was observed, especially when they occur bilaterally. CLINICAL RELEVANCE: The results in the present study have a clinical relevance in the diagnosis of children with dental anomalies in primary dentition. Early identification of these anomalies can aid the dentist in planning dental treatment at the appropriate time.

Persistência de plantas medicinais em sistemas agroflorestais no município de São Bento do Sul, SC, Brasil / Persistence of medicinal plants in agroforestry systems in the city of São Bento do Sul, Santa Catarina, Brazil

No final da década de 90, a comunidade de Rio Natal, no município de São Bento do Sul, SC, passou a fazer parte de uma Área de Preservação Ambiental e desde então, muitas áreas de cultivo, paulatinamente, estão retomando o processo de formação florestal. Neste cenário, foi sugerido pela comunidade, a possibilidade de cultivo de plantas medicinais adaptadas às condições de sombreamento. Em atendimento a essa demanda foi realizada uma pesquisa participativa na comunidade, de 2005 a 2008, onde foram avaliadas 14 espécies de plantas medicinais com potencial de mercado, cultivadas em áreas sombreadas, em três propriedades familiares. Foram avaliados: taxa de sobrevivência das espécies, incidência de doenças e pragas, teor de massa seca e altura das plantas. Apresentaram persistência ao cultivo em áreas sombreadas as espécies: Curcuma longa L. (açafrão-da-índia); Arctium lappa L. (bardana); Pfaffia glomerata (Spreng) Pedersen (fáfia ou ginseng-brasileiro); Mikania glomerata Sprengel (guaco); Alternanthera brasiliana L. Kuntze (penicilina); Pogostemon cablin (Blanco) Benth (patchuli) e Maytenus ilicifolia Mart. Ex Reissek (espinheira-santa).

In the end of the 1990s, the Rio Natal community, located in the city of São Bento do Sul, in the Brazilian State of Santa Catarina, started to be part of an Environmental Protection Area. Since then, many cultivation areas have been increasingly having their forest restored. In this scenario, the community proposed to cultivate medicinal plants that were adapted to shaded conditions. To attend this demand, we carried out a participatory research in the community between 2005 and 2008. Fourteen species of medicinal plants having market potential were evaluated, and were cultivated in shaded areas, in three family properties. The survival of the species, the incidence of illnesses and pests, the dry matter value and the height of the plants were evaluated. The species that presented persistence to be cultivated in shaded areas were: Curcuma longa L.; Arctium lappa L.; Pfaffia glomerata (Spreng) Pedersen.; Mikania glomerata Sprengel.; Alternanthera sp.; Pogostemon cablin (Blanco) Benth. e Maytenus ilicifolia Mart. Ex Reissek.

Autosomal-dominant ankyloglossia and tooth number anomalies.

Ankyloglossia is a congenital oral anomaly characterized by the presence of a hypertrophic lingual frenulum. It frequently accompanies X-linked cleft palate and is sometimes seen alone due to mutations in the gene encoding the transcription factor TBX22, while knockout of Lgr5 in the mouse results in ankyloglossia. The aim of the present study was to characterize the phenotype and to verify sequence variations in the LGR5 gene in a Brazilian family with ankyloglossia associated with tooth number anomalies. Twelve individuals of three generations were submitted to physical, oral, and radiographic examinations and molecular analysis. Eight had ankyloglossia with various degrees of severity. Six also had hypodontia in the lower incisor region; one had a supernumerary tooth in this region, and another had a supernumerary tooth in the lower premolar region. The characterization of this family determined an autosomal-dominant inheritance and excluded the LGR5 gene mutations as being involved in the pathogenesis of this condition.

CD4+CD25+Foxp3+ indirect alloreactive T cells from renal transplant patients suppress both the direct and indirect pathways of allorecognition.

Alloreactive T cells recognize donor antigens by two routes: direct and indirect pathways of allorecognition. Although the direct pathway is reported to be dominant in allograft rejection, indirect allorecognition also plays an important role. Indirect alloreactivity is also observed in renal transplant patients irrespective of rejection. Previously we showed a predominance of interleukin (IL)-10 induced by indirect allorecognition of donor human leucocyte antigen (HLA)-DR peptides, suggesting the existence of indirect alloreactive T cells displaying regulatory activity. In the present work, our objective was to characterize these regulatory T cells. We detected indirect alloproliferation of peripheral blood mononuclear cells (PBMC) from renal transplant patients, induced by donor HLA-DR peptides, dependent on IL-4 or IL-10, suggesting regulatory activity as part of the alloreactive T-cell repertoire. PBMC-derived indirect alloreactive T-cell lines were established and produced both inflammatory and regulatory cytokines. We showed that two of these T-cell lines which were able to inhibit both direct and indirect alloproliferation of another T-cell line from the same patient presented a CD4(+)CD25(+)Foxp3(+) T-cell population. These data support the idea that indirect alloreactive T cells may also have regulatory activity and may contribute to the maintenance of the human renal allograft.

CD4+CD25+Foxp3+ indirect alloreactive T cells from renal transplant patients suppress both the direct and indirect pathways of allorecognition

Alloreactive T cells recognize donor antigens by two routes: direct and indirect pathways of allorecognition. Although the direct pathway is reported to be dominant in allograft rejection, indirect allorecognition also plays an important role. Indirect alloreactivity is also observed in renal transplant patients irrespective of rejection. Previously we showed a predominance of interleukin (IL)-10 induced by indirect allorecognition of donor human leucocyte antigen (HLA)-DR peptides, suggesting the existence of indirect alloreactive T cells displaying regulatory activity. In the present work, our objective was to characterize these regulatory T cells. We detected indirect alloproliferation of peripheral blood mononuclear cells (PBMC) from renal transplant patients, induced by donor HLA-DR peptides, dependent on IL-4 or IL-10, suggesting regulatory activity as part of the alloreactive T-cell repertoire. PBMC-derived indirect alloreactive T-cell lines were established and produced both inflammatory and regulatory cytokines. We showed that two of these T-cell lines which were able to inhibit both direct and indirect alloproliferation of another T-cell line from the same patient presented a CD4+CD25 +Foxp3+ T-cell population. These data support the idea that indirect alloreactive T cells may also have regulatory activity and may contribute to the maintenance of the human renal allograft.

Cellular autoreactivity against heat shock protein 60 in renal transplant patients: peripheral and graft-infiltrating responses.

Autoreactivity to heat shock protein 60 (Hsp60) has been implicated in the pathogenesis and regulation of chronic inflammation, especially in autoimmune diseases. In transplantation, there is a lack of information regarding the cytokine profile and specificity of cells that recognize self-Hsp60 as well as the kinetics of autoreactivity following transplantation. We studied the cellular reactivity of peripheral and graft-infiltrating lymphocytes against Hsp60 in renal transplant patients. Cytokine production induced by this protein in peripheral blood mononuclear cells indicated a predominance of interleukin (IL)-10 during the late post-transplantation period, mainly in response to intermediate and C-terminal peptides. Patients with chronic rejection presented reactivity to Hsp60 with a higher IL-10/interferon (IFN)-gamma ratio compared to long-term clinically stable patients. Graft-infiltrating T cell lines, cocultured with antigen-presenting cells, preferentially produced IL-10 after Hsp60 stimulation. These results suggest that, besides its proinflammatory activity, autoreactivity to Hsp60 in transplantation may also have a regulatory role.

Identifying cyclosporine blood levels associated with the prevention of renal transplant rejection: a single-center, randomized prospective study.

Multiple-drug therapy may allow reduced individual drug doses with fewer side effects. Blood levels of cyclosporine (CsA) necessary to avoid rejection may vary with different drug combinations. Fifty-eight kidney transplant patients were randomized into two groups: 25 subjects were assigned to the 4-hour area under the curve (AUC(0-4)) Cohort-the "high arm" (4500 to 5500 ng . h/mL)--1 and 33 to the AUC(0-4) "low arm" (2400 to 3400 ng . h/mL). After CsA introduction, AUC(0-4) was drawn on days 4, 7, 14, 21, 28, 42, 56, 70, 84, 90. We compared the proportion of rejection versus rejection-free patients, according to the CsA exposure. Logistic regression analysis showed that an AUC(0-4) of > or =4000 ng . h/mL or a 2-hour cyclosporine level (C(2)) of > or =1450 ng/mL predicted a rejection-free course among patients not receiving induction therapy. When either basiliximab or thymoglobulin was administered, a C(2) and AUC(0-4) of 1043 +/- 151 ng/mL or 3146 +/- 262 ng . h/mL, respectively, were associated with a rejection-free course. Our findings confirm the need for different CsA levels to prevent rejection according to induction therapy. Induction with either basiliximab or thymoglobulin allows reduced CsA levels during the first 3 months after renal transplantation.

T-cell response to self HSP60 peptides in renal transplant recipients: a regulatory role?

T-cell responses to heat shock proteins (Hsp) have been suggested to play a role not only in inflammatory conditions, but also in various human autoimmune diseases and in the allograft response. Previous data from our group suggested that during the early posttransplantation (post-Tx) period (<6 months post-Tx), the anti-Hsp60 T-cell repertoires in renal transplant recipients were predominantly proinflammatory. In the later period, they were predominantly regulatory. In agreement with our results, diversification of the T-cell responses toward the carboxy-terminal determinants of Hsp60, related to the resolution of the inflammatory process, was shown in an experimental model of adjuvant arthritis. It has not been clarified whether this diversification is also present in transplantation. In this context, our objective was to analyze cytokine production against autologous Hsp60 peptides from different regions of the protein, using peripheral blood mononuclear cells of 9 renal transplant recipients at 2 timepoints after transplantation: early (<6 months) and late (>1 year). IFN gamma production induced by Hsp60 peptides was observed in 71% and 75% of the patients in the early and late post-Tx periods, respectively. Interleukin (IL)-10 production induced by Hsp60 peptides was observed in 28% of the patients in the early period and in 62% in the late period. Interestingly, the production of IL-10 was induced mainly by peptides of the intermediate and the C-terminal regions. This suggests a predominance of autoreactive regulatory anti-Hsp T-cell repertoire in the late post-Tx period, which predominantly recognize peptides from the intermediate and C-terminal regions of the protein.

Predominant IL-10 production in indirect alloreactivity is not associated with rejection.

In a prospective study of indirect alloresponse in renal transplantation, we detected proliferation and cytokine production to donor and third-party HLA-DR peptides unrelated to rejection. Twenty of 28 patients (71%) presented proliferation, 29% before and 71% after transplantation. Half of the patients also presented proliferation to third-party peptides. Indirect alloresponse was also detected in 75% of healthy individuals (HI). Variability of response was observed in patients and HI for both proliferation and cytokine production. IL-10 predominance was observed in indirect alloresponses to donor peptides pre- and post-Tx, in contrast with more IFN-gamma and TGF-beta being detected in HI. IL-10 production was frequently detected without proliferation, in contrast with more frequent proliferation being found with IFN-gamma and TGF-beta production. The lack of association of either cytokine or proliferation with rejection, together with the predominance of IL-10 unrelated to proliferation, suggests that regulatory cells may be part of the T cell repertoire involved in indirect alloreactivity.

Renal transplant patients show variations in their self-reactive repertoires: a serial study.

We addressed the question of whether allo-transplantation (Tx) induces breakdown of tolerance to self-antigens or alteration of the autoreactive T cell repertoire in humans. The serial variation of T cell autoreactivity was studied in the peripheral blood of 12 renal transplant patients, by autologous limiting dilution assay and autologous mixed lymphocyte reaction. Ten of 12 patients presented a positive response in autologous peripheral blood mononuclear cells in the post-Tx period, in contrast to four of 12 patients before Tx (P = 0.038). Multi-hit kinetics was found in 57% of the assays analyzed, indicating frequent regulatory control of the autologous response. Quantitative analysis performed in eight patients showed an increase in precursor frequency at >1 year post-Tx in five patients. These data indicate that autoreactivity increases or develops following Tx, in humans. Post-Tx events such as alloreactivity, infections or immunosuppression could interfere with the balance of autoreactive and regulatory cells, leading to changes in the T cell repertoires to self-antigens and eventually breakdown of self-tolerance. Further investigation is needed to elucidate whether post-Tx autoreactivity contributes to rejection, plays a regulatory role over alloreactivity or both, at separate times.

Dialysis, time and death: comparisons of two consecutive decades among patients treated at the same Brazilian dialysis center.

The survival of hemodialysis patients is likely to be influenced not only by well-known risk factors like age and comorbidity, but also by changes in dialysis technology and practices accumulated along time. We compared the survival curves, dialysis routines and some risk factors of two groups of patients admitted to a Brazilian maintenance hemodialysis program during two consecutive decades: March 1977 to December 1986 (group 1, N = 162) and January 1987 to June 1997 (group 2, N = 237). The median treatment time was 22 months (range 1-198). Survival curves were constructed using the Kaplan-Meier method and compared using the log-rank method. The Cox proportional hazard regression model was used to investigate the more important variables associated with outcome. The most important changes in dialysis routine and in patient care during the total period of observation were the progressive increase in the dose of dialysis delivered, the prohibition of potassium-free dialysate, the use of bicarbonate as a buffer and the upgrading of the dialysis equipment. There were no significant differences between the survival curves of the two groups. Survival rates at 1, 5 and 10 years were 84, 53 and 29%, respectively, for group 1 and 77, 42 and 21% for group 2. Patients in group 1 were younger (45.5 +/- 15.2 vs 52.2 +/- 15.9 years, P < 0.001) and had a lower prevalence of diabetes (11.1 vs 27.4%, P < 0.001) and of cardiovascular disease (9.3 vs 20.7%, P < 0.001). According to the Cox multivariate model, only age (hazard ratio (HR) 1.04, confidence interval (CI) 1.03-1.05, P < 0.001) and diabetes (HR 2.55, CI 1.82-3.58, P < 0.001) were independent predictors of mortality for the whole group. Patients of group 2 had a lower prevalence of sudden death (19.1 vs 9.7%, P < 0.001). After adjusting for age, diabetes and other mortality risk factors, the risk of death was 17% lower in group 2, although this difference was not statistically significant. We conclude that the negative effects of advanced age and of higher frequency of comorbidity on the survival of group 2 patients were probably offset by improvements in patient care and in the quality and dose of dialysis delivered, so that the survival curves did not undergo significant changes along time.

Evidence of indirect allorecognition in long-term human renal transplantation.

The purpose of this study was to investigate indirect alloreactivity in the peripheral blood of long-term renal transplanted patients. We evaluated the T cell proliferative response to a whole pool of donor cell-derived allopeptides, processed and presented by host antigen-presenting cells (APC), rather than to synthetic peptides. For the indirect pathway, proliferation assays were performed using APC-depleted donor cells. Indirect alloreactivity was detected in 57% (8/14) of the patients, 6 of whom presented no evidence of rejection, but 2 patients had a diagnosis of chronic rejection. In 4 of 8 positive cases (50%), proliferation was detected with 5 days of culture, and sometimes indirect alloresponse was the dominant route. We present evidence that the indirect alloproliferative response to a pool of naturally processed donor peptides is present in the peripheral blood of long-term renal transplanted patients irrespective of rejection.

Dialysis, time and death: comparisons of two consecutive decades among patients treated at the same Brazilian dialysis center

The survival of hemodialysis patients is likely to be influenced not only by well-known risk factors like age and comorbidity, but also by changes in dialysis technology and practices accumulated along time. We compared the survival curves, dialysis routines and some risk factors of two groups of patients admitted to a Brazilian maintenance hemodialysis program during two consecutive decades: March 1977 to December 1986 (group 1, N = 162) and January 1987 to June 1997 (group 2, N = 237). The median treatment time was 22 months (range 1-198). Survival curves were constructed using the Kaplan-Meier method and compared using the log-rank method. The Cox proportional hazard regression model was used to investigate the more important variables associated with outcome. The most important changes in dialysis routine and in patient care during the total period of observation were the progressive increase in the dose of dialysis delivered, the prohibition of potassium-free dialysate, the use of bicarbonate as a buffer and the upgrading of the dialysis equipment. There were no significant differences between the survival curves of the two groups. Survival rates at 1, 5 and 10 years were 84, 53 and 29 percent, respectively, for group 1 and 77, 42 and 21 percent for group 2. Patients in group 1 were younger (45.5 = 15.2 vs 55.2 = 15.9 years, P<0.001) and had a lower prevalence of diabetes (11.1 vs 27.4 percent, P<0.001) and of cardiovascular disease (9.3 vs 20.7 percent, P<0.001). According to the Cox multivariate model, only age (hazard ratio (HR) 1.04, confidence interval (CI) 1.03-1.05, P<0.001) and diabetes (HR 2.55, CI 1.82-3.58, P<0.001) were independent predictors of mortality for the whole group. Patients of group 2 had a lower prevalence of sudden death (19.1 vs 9.7 percent, P<0.001). After adjusting for age, diabetes and other mortality risk factors, the risk of death was 17 percent lower in group 2, although this difference was not statistically significant. We conclude that the negative effects of advanced age and of higher frequency of comorbidity on the survival of group 2 patients were probably offset by improvements in patient care and in the quality and dose of dialysis delivered, so that the survival curves did not undergo significant changes along time

Outcome of patients with malignant hypertension and end-stage renal failure treated by long-term hemodialysis.

Malignant hypertension is associated with high mortality and morbidity usually caused by cardiovascular events. The course and prognosis of malignant hypertension patients treated with renal replacement therapy has not been thoroughly investigated. In the present work, we compared the clinical evolution and survival of 24 end-stage renal failure malignant hypertension patients with that of a group of individually matched renal failure patients admitted to the same dialysis center during a period of 21 years. Survival rates at 1, 5 and 8 years were 87, 82 and 50% for malignant hypertension patients and 87, 75 and 65% for controls, respectively (p = 0.766, NS). Nonfatal cardiovascular complications occurred in 2 individuals of each group. The most important cause of death in both groups was cardiovascular. The frequency of fatal cardiovascular events was similar in the two groups: 64% of deaths for malignant hypertension and 71% for controls (NS). In conclusion, previous malignant hypertension did not increase the risk of patients in long-term hemodialysis in our series.

Baseline variables associated with early death and extended survival on dialysis.

Patients who die during the first three months on dialysis are not systematically included in the American and European statistics. In contrast, only a few patients survive more than 10 years on this modality of renal replacement therapy. The factors determining these two extreme forms of outcome are poorly understood. We tested the hypothesis that a few variables, easily obtainable at the initiation of dialysis, would identify those individuals at high and low risk of early death. We retrospectively studied 23 patients who died within 90 days of initiating dialysis and 20 patients who survived more than 10 years. These patients were admitted for dialysis to a Brazilian center between July 1, 1976 and February 28, 1997. The baseline variables assessed which were thought to influence survival, were: age, sex, race, body weight, etiology of renal disease, blood pressure, comorbid conditions, hematocrit and serum electrolytes, albumin, creatinine, urea, and urea/creatinine ratio. Univariate analysis showed that patients who died early were older (56.2 +/- 15.6 vs. 42.1 +/- 10.4 years, p < 0.01), had lower serum creatinine (10.6 +/- 2.9 vs. 13.7 +/- 3.7 mg/dL, p < 0.01) and albumin (3.3 +/- 0.9 vs. 4.0 +/- 0.5 g/dL) and a higher urea/creatinine ratio (18.4 +/- 5.8 vs. 13.5 +/- 4.8, p < 0.01) compared with subjects surviving more than 10 years. Early death patients also had more cases of diabetes (35% vs. 0%, p < 0.01) and less chronic glomerulonephritis (9% vs. 35%, p < 0.05). Multivariate analysis showed that age (p < 0.01, CI 1.02 to 1.15, odds ratio 1.1) and urea/creatinine ratio (p < 0.01, CI 1.03 to 1.38, odds ratio 1.2) were positively and independently related to outcome. In the early death group, malnutrition was an important cause of death (17% of all deaths). Compared to baseline data, long-term survivors, at the last follow up, presented reduced systolic blood pressure and increased hematocrit and unchanged body weight, serum albumin and urea/creatinine ratio. These results, based on easily accessible initial variables, suggest that early death on dialysis is influenced by age and by indices related to the nutritional condition of the patients. They also highlight the importance of a potentially correctable risk factor in a population with an elevated prevalence of premature death.

Comparison of echocardiographic changes associated with hemodialysis and renal transplantation.

Long-term hemodialysis has been reported to cause progression of left ventricular (LV) hypertrophy with a tendency toward asymmetric septal hypertrophy. Renal transplantation is believed to reverse some of these changes. The aim of this prospective study was to compare the effects of long-term hemodialysis and of successful renal transplantation on cardiac structure and function assessed by echocardiography. Fifty-three patients were submitted to two echocardiographic evaluations separated by a 30 +/- 8 month interval. At the first control, all patients were on hemodialysis; at the second, 36 patients remained on dialysis while 17 had been submitted to renal transplantation. Age (44 +/- 13 vs. 40 +/- 10 years), gender (male, 50% vs 53%), and duration of dialysis at the initiation of the study (43 +/- 34 vs. 47 +/- 32 months) were comparable in the 2 groups. The prevalence of LV hypertrophy were 83% (first control) and 69% (second control) in the dialysis group and 82% and 71% in the transplant group. Comparisons between the two periods within each group showed that hemodialysis was associated with a significant reduction of the E/A ratio (1.25 +/- 0.4 vs. 1.02 +/- 0.4, p < 0.001) and systolic (155 +/- 28 vs. 137 +/- 26 mm Hg, p < 0.001) and diastolic (94 +/- 21 vs. 84 +/- 16 mm Hg, p < 0.05) blood pressure, and no change in LV mass index (171 +/- 51 vs. 156 +/- 43 g/m2, NS). In the transplanted group, there were reductions in the E/A ratio (1.42 +/- 0.6 vs 1.10 +/- 0.4, p < 0.05) and in LV diastolic dimension (50 +/- 7 vs. 46 +/- 5 mm, p < 0.05), but not in systolic (155 +/- 27 vs. 152 +/- 31 mm Hg, NS) or diastolic (97 +/- 11 vs. 97 +/- 20 mm Hg, NS) blood pressure. The LV mass index also did not change significantly (157 +/- 51 vs. 133 +/- 31 g/m2, NS).(ABSTRACT TRUNCATED AT 250 WORDS)