Cardiothoracic surgery and peripheral endovascular intervention in cardiovascular damage from a cohort of orphan rheumatological diseases-epidemiological and survival analysis.

Background: Aortic diseases in some orphan rheumatological diseases require medical, surgical or peripheral endovascular intervention because they can be catastrophic. Objectives: to analyze the main clinical and epidemiological characteristics of patients with Takayasu arteritis (TA), Marfan syndrome (MS) and similar conditions that were treated with cardiothoracic surgery and peripheral endovascular intervention. Methods: Retrospective and descriptive cohort study that included patients of any age and gender with TA (as per the criteria of the American College of Rheumatology and EULAR/PRINTO), MS (according to Ghent criteria), and similar conditions who underwent cardiothoracic surgery or peripheral endovascular intervention. Data were collected from electronic charts. Results: A total of 77 patients with TA and 135 patients with MS and similar conditions were included. The frequency of surgical or interventional requirements in patients with TA and MS/similar conditions was 77/364 (21.2%) and 135/300 (45%), respectively; such patients were followed for a median of 6 [2-12] and 3.29 (0.42-6.62) years, with (maximum follow-up range of 47 and 21.37 years, respectively). Aneurysms were present in 11 (14.3%) and 66 (48.9%) in patients with TA and MS/similar conditions, respectively. Aortic, mitral and tricuspid valve damage occurred in 8 (10.4%) patients, 4 (5.2%) patients and 1 (1.3%) patient with TA, respectively; corresponding frequencies in patients with MS/similar conditions were 98 (72.6%), 50 (37.0%) and 20 (14.8%). We identified that 20% of patients with TA died after 5.08 years (95% CI: 0.23-25.42 years) and 20 % of the patients with MS and other similar conditions died after 7.52 years (95% CI: 1.10-9.02 years). Conclusions: The frequency of surgical intervention was low in this study. Long-term prognosis is good if surgery is performed in a timely manner. Epidemiological studies provide relevant information for public health decisions related to the management of orphan rheumatological diseases.

Recombinant Enolase of Trypanosoma cruzi as a Novel Vaccine Candidate against Chagas Disease in a Mouse Model of Acute Infection.

Trypanosoma cruzi is the protozoan parasite that causes Chagas disease, which is considered by the World Health Organization to be a neglected tropical disease. Two drugs exist for the treatment of Chagas disease, nifurtimox and benznidazole; they are only effective in the acute phase, and a vaccine is currently not available. In this study, we used the recombinant enolase from T. cruzi H8 strain (MHOM/MX/1992/H8 Yucatán) (rTcENO) and its encoding DNA (pBKTcENO) to immunize mice and evaluate their protective effects in an experimental murine model of acute phase infection. Our results showed that mice vaccinated with rTcENO or its encoding DNA were able to generate typical specific antibodies (IgG1, IgG2a, and IgG2b), suggesting that a mixed Th1/Th2 immune response was induced. The parasite burden in the blood was reduced to 69.8% and 71% in mice vaccinated with rTcENO and pBKTcENO, respectively. The group vaccinated with rTcENO achieved 75% survival, in contrast to the group vaccinated with pBKTcENO that showed no survival in comparison to the control groups. Moreover, rTcENO immunization elevated the production of IFN-γ and IL-2 after the parasite challenge, suggesting that the Th1-type immune response was polarized. These results indicated that rTcENO could be used as a vaccine against Chagas disease.

Obesity, Thrombotic Risk, and Inflammation in Cancer.

Neoplasms exhibits a high incidence and mortality rates due to their complex and commonly overlapping clinical, biochemical, and morphologic profiles influenced by acquired or inherited molecular abnormalities, cell of origin, and level of differentiation. Obesity appears related to ~20% of cancers including endometrial, esophageal, colorectal, postmenopausal breast, prostate, and renal. Several factors other than obesity, i.e., insulin, insulin-like growth factor, sexual hormones, and adipokines may play a potential role in neoplasia. Cancer-associated hypercoagulable and thrombotic states are influenced by abnormalities in the vascular wall and susceptibility to invasion, interference in blood flow and increase in circulating tissue factor and thrombin, activation of cell growth factors, the presence of a central catheter, chemotherapies, neoplasm type, and surgery. In cancer, thromboembolic complications are the second most frequent cause of death with pulmonary thromboembolism in ~50% of cases postmortem. Thrombosis worsens prognosis as demonstrated with a survival rate as low as 12% per year vs 36% in nonthrombic patients. Deep vein thrombosis is the most frequent thromboembolic complication in cancer. It is usually detected at diagnosis and within the first 3 months of chemotherapy. The underlining mechanisms of this association should be further studied to identify patients at higher risk and develop adequate prevention, diagnostic, and treatment measures. The D-dimer test can be successfully used to assess the fibrinolytic phase of coagulation and as such is routinely used in suspected cases of deep vein thrombosis and pulmonary thromboembolism. In addition, significant advances have been made in understanding the composition and functional capabilities of the gut microbiota in the inflammatory process, obesity, and its roles in cancer; however, the intricate balance that exists within the microbiota may not only affect the host directly, it can also disrupt the entire microbial community. CONCLUSIONS: Cancer is a prothrombotic and inflammatory state in which the activation of coagulation is related to tumor growth, angiogenesis, and metastasis. It is important to identify the relationship between body mass index with these processes and clarify their importance in cancer prognosis. Future research should answer the question if manipulation of resident microbial communities could potentially improve prognosis and treatment outcome.

Serum cytokines and activation ex vivo of CD4+ and CD8+ T cells in chagasic chronic Mexican patients

The clinical manifestations of human Chagas disease are associated with several factors, including immunological alterations, in this regard, many studies propose that tissue damage might be more severe in the absence of immune regulatory mechanisms, other factors are the genetic background of host and parasite. Trypanosoma cruzi population is genetically, biochemistry and pathogenic diverse along the Latin-America continent and phylogenetic ally are divided into six intra-species lineages TcI-VI. The TcI lineage has a wide distribution with heterogeneous virulence and pathogenesis within strains. In Mexico, the main circulating lineage is TcI in human infections. We analyzed intracytoplasmic cytokines of unstimulated peripheral T lymphocytes, and the level of cytokines (IL-2, IL-4, IL-12, IL-10, IFN-γ and sIL-2R) in the serum of Mexican chagasic subjects. The population studied consisted of 15 asymptomatic individuals, 17 patients with chronic chagasic cardiopathy (CCC), 20 patients with cardiopathy but negative serology for T. cruzi, and 10 healthy subjects. The analysis of CD4+ cells revealed that CCC and asymptomatic patients have higher CD25+ and CD69 activation markers than controls. The Th1 subset (CD4+/IFN- γ +) was higher in CCC than in asymptomatic and control subjects, whereas Th2 subset was markedly high in asymptomatic subjects. Circulating cytokines were below level detection with the exception of IL-2 and sIL-2R. Infection with Mexican Trypanosoma cruzi strains in asymptomatic chagasic subjects have a tendency for a Th2 response with higher CD8+/IFN-γ T cells. In contrast, CCC patients have low levels of intracellular IFN- γ and IL-2 cytokines. In both groups circulating serum cytokines are below the detectable level.

The interleukin-1 gene cluster polymorphisms are associated with Takayasu's arteritis in Mexican patients.

Takayasu's arteritis (TA) is a chronic inflammatory arteritis of unknown etiology involving mainly the aorta and its major branches. The interleukin (IL) 1ß and IL-1 receptor antagonist have been playing an important role as regulators of inflammation. We investigated whether the polymorphisms at the IL-1B and IL-1RN gene cluster were associated with the genetic susceptibility to develop TA. We analyzed the IL-1B, IL-1F10.3, and IL-1RN polymorphisms in a sample of 58 TA patients, and 248 clinically healthy unrelated Mexican individuals by 5' exonuclease TaqMan polymerase chain reaction. Polymorphic haplotypes were constructed after linkage disequilibrium analysis. We found increased frequencies of different polymorphisms (C allele and TC genotype of IL-1F10.3; TT genotype of IL-1RN.4; C allele and TC genotype of IL-1RN6.1; G allele of IL-1RN6.2 and haplotypes "1T" and "1C" of IL-RN VNTR and IL-1RN6.1) in the group of TA when compared to healthy controls. On the other hand, decreased frequency of IL-1-511 TC genotype was found in the TA group compared to controls. IL-1B and IL-1RN gene polymorphisms could be involved in the risk of developing TA in the Mexican population. These associations were independent of the affected vessels.

Specific humoral and cellular immunity induced by Trypanosoma cruzi DNA immunization in a canine model.

Chagas disease has a high incidence in Mexico and other Latin American countries. Because one of the most important known methods of prevention is vector control, which has been effective only in certain areas of South America, the development of a vaccine to protect people at risk has been proposed. In this study, we assessed the cellular and humoral immune response generated following immunization with pBCSP and pBCSSP4 plasmids containing the genes encoding a trans-sialidase protein (present in all three forms of T. cruzi) and an amastigote specific glycoprotein, respectively, in a canine model. Thirty-five beagle dogs were divided randomly into 5 groups (n=7) and were immunized twice intramuscularly with 500 µg of pBCSSP4, pBCSP, pBk-CMV (empty plasmid) or saline solution. Fifteen days after the last immunization the 4 groups were infected intraperitoneally with 500,000 metacyclic trypomastigotes. The fifth group was unimmunized/infected. The parasitaemia in the immunized/infected dogs was for a shorter period (14 vs. 29 days) and the parasite load was lower. The concentration of IgG1 (0.612±0.019 O.D.) and IgG2 (1.167±0.097 O.D.) subclasses was measured (absorbance) 15 days after the last immunization with both recombinant plasmids, the majority of which were IgG2. The treatment of parasites using the serum from dogs immunized with pBCSP and pBCSSP4 plasmids produced 54% (±11.8) and 68% (±21.4) complement-mediated lysis, respectively. At 12 h post immunization, an increase in cytokines was not observed; however, vaccination with pBCSSP4 significantly increased the levels of IFN-γ and IL-10 at 9 months post-infection. The recombinant plasmid immunization stimulated the spleen cell proliferation showing a positive stimulatory index above 2.0. In conclusion, immunization using both genes effectively induces a humoral and cellular immune response.

Plasmid DNA immunization with Trypanosoma cruzi genes induces cardiac and clinical protection against Chagas disease in the canine model.

The only existing preventive measure against American trypanosomosis, or Chagas disease, is the control of the transmitting insect, which has only been effective in a few South American regions. Currently, there is no vaccine available to prevent this disease. Here, we present the clinical and cardiac levels of protection induced by expression to Trypanosoma cruzi genes encoding the TcSP and TcSSP4 proteins in the canine model. Physical examination, diagnostic chagasic serology, and serial electrocardiograms were performed before and after immunization, as well as after experimental infection. We found that immunization with recombinant plasmids prevented hyperthermia in the acute phase of experimental infection and produced lymphadenomegaly as an immunological response against the parasite and additionally prevented heart rate elevation (tachycardia) in the acute and/or chronic stages of infection. Immunization with T. cruzi genes encoding the TcSP and TcSSP4 antigens diminished the quality and quantity of the electrocardiographic abnormalities, thereby avoiding progression to more severe developments such as right bundle branch block or ventricular premature complexes in a greater number of dogs.

Detection of IS6110 and HupB gene sequences of Mycobacterium tuberculosis and bovis in the aortic tissue of patients with Takayasu's arteritis.

BACKGROUND: Takayasu's arteritis (TA) is a chronic inflammatory disease affecting the large arteries and their branches; its etiology is still unknown. In individuals suffering from TA, arterial inflammation progresses to stenosis and/or occlusion, leading to organ damage and affecting survival. Relation of TA with Mycobacterium tuberculosis has been known, but there have been only a few systematic studies focusing on this association. The IS6110 sequence identifies the Mycobacterium tuberculosis complex and the HupB establishes the differences between M. tuberculosis and M. bovis. Our objective was to search the presence of IS6110 and HupB genes in aorta of patients with TA. METHODS: We analyzed aorta tissues embedded in paraffin from 5760 autopsies obtained from our institution, we divided the selected samples as cases and controls; CASES: aortic tissues of individuals with Takayasu's arteritis. Control positive: aortic tissues (with tuberculosis disease confirmed) and control negative with other disease aortic (atherosclerosis). RESULTS: Of 181 selected aorta tissues, 119 fulfilled the corresponding criteria for TA, TB or atherosclerosis. Thus 33 corresponded to TA, 33 to tuberculosis (TB) and 53 to atherosclerosis. The mean age was 22 ± 13, 41 ± 19, and 57 ± 10, respectively. IS6110 and HupB sequences were detected in 70% of TA tissues, 82% in tuberculosis, and in 32% with atherosclerosis. Important statistical differences between groups with TA, tuberculosis versus atherosclerosis (p = 0.004 and 0.0001, respectively) were found. CONCLUSION: We identified a higher frequency of IS6110 and HupB genes in aortic tissues of TA patients. This data suggests that arterial damage could occur due to previous infection with M. tuberculosis.

Trypanosoma cruzi connatal transmission in dogs with Chagas disease: experimental case report.

Trypanosoma cruzi connatal transmission was studied in male and female mongrel dogs. Both dogs were experimentally infected, after which on the 20(th) day, lymphoadenomegaly and fever were found. Four months postinfection, they mated. At this time, Chagas disease was confirmed by two different diagnostic tests. The electrocardiogram and echocardiogram taken at the eight postinoculation month showed data consistent with ischemia, local conduction abnormalities and hypertrophy, as well as a diminished ejection fraction and left ventricular dilation, respectively. Four puppies were born and after weaning had weakness, progressive weight loss, and chronic diarrhea. Necropsy of all four showed digestive alterations and cardiac dilation. Serology in the offspring was positive for Chagas disease. The histopathological study demonstrated a cardiac chronic inflammatory process, although no parasites were found. Clinical data and serological determinations are consistent with death from advanced Chagas disease.

Coronary CT angiography in Takayasu arteritis.

OBJECTIVES: The aim of this study was to use coronary computed tomographic (CT) angiography to characterize coronary artery involvement in patients with known Takayasu arteritis who present with anginal chest pain or shortness of breath. BACKGROUND: Takayasu arteritis is a primary vasculitis of the large vessels, which mainly affects the aorta and its branches but can also involve the coronary arteries. Coronary CT angiography allows visualization of the coronary vessels and can be used to detect both stenotic and nonstenotic coronary artery lesions. METHODS: Eighteen consecutive patients with Takayasu arteritis and angina (typical or atypical) and/or dyspnea underwent contrast-enhanced 64-slice coronary CT angiography. The arterial injury was classified according to the Numano classification. Three patients had prior known coronary artery disease. Coronary arteries were evaluated concerning the presence of obstructive and nonobstructive lesions, and differences between the clinical presentations of patients with and without coronary artery involvement on CT angiography were analyzed. RESULTS: Coronary artery involvement was found in 8 patients (44.4%), 3 of them with clinical activity. A total of 19 coronary lesions were present (13 in ostial locations, 5 in proximal coronary artery segments, and 1 in a mid segment). Eight lesions exceeded 50% diameter reduction (2 in ostial locations and 6 in proximal coronary artery segments). Median disease duration was significantly different between patients with coronary artery involvement (176 months; range 13 to 282 months) compared with those without (21 months; range 1 to 142 months) (p = 0.013). CONCLUSIONS: Coronary CT angiography allows the assessment of coronary artery involvement in patients with Takayasu arteritis. These data confirm prior observations that most coronary lesions are in ostial or proximal coronary artery locations. Disease duration in patients with coronary artery involvement is longer than in patients without.

[Some ethical dilemmas in the medical praxis]. / Algunos dilemas éticos en la práctica médica.

We reviewed from a bioethical perspective and attempting prevention of potential conflicts derived communication failure during medical practice, palliative treatments and dignified death in the institutional practice as well as general practice; most of conflicts related to patient-doctor relationship could de prevented. We propose an attitude and aptitude plus in deep knowledge of patient, family, friends and legal representatives in terms fully honest communication to prevent most of conflicts and avoid its consequences against doctors and other health workers. Prevention is better and it depends of knowledge of norms, laws, general beliefs and common sense in this country and maybe others.

Algunos dilemas éticos en la práctica médica / Some ethical dilemmas in the medical praxis

Con la intención de prevenir conflictos en el acto médico y desde el punto de vista bioético, éste, el manejo paliativo y de la muerte digna; situaciones que pueden ser fuente de demandas entre el paciente y el médico. Sostenemos que la actitud y aptitud del médico, del paciente, su familia, amigos y representantes legales, con apertura y honestidad, pueden prevenir la gran mayoría de las causas de conflicto y evitar las consecuencias del mismo entre los profesionales de la salud y los enfermos. La prevención es posible si hay buena voluntad y conocimiento de normas, leyes, usos y sentido común.

We reviewed from a bioethical perspective and attempting prevention of potential conflicts derived communication failure during medical practice, palliative treatments and dignified death in the institutional practice as well as general practice; most of conflicts related to patient-doctor relationship could de prevented. We propose an attitude and aptitude plus in deep knowledge of patient, family, friends and legal representatives in terms fully honest communication to prevent most of conflicts and avoid its consequences against doctors and other health workers. Prevention is better and it depends of knowledge of norms, laws, general beliefs and common sense in this country and maybe others.

Echocardiographic study of a Mestizo-Mexican population with Marfan syndrome.

BACKGROUND: The cardiovascular manifestations of Marfan syndrome (MFS) are the main causes of morbidity and mortality. This study describes the clinical and echocardiographic findings in a Mestizo-Mexican population affected by the disease. METHODS: A total of 166 patients previously diagnosed with MFS were recruited for the study, 114 of them underwent complete clinical history, with emphasis on Ghent nosology criteria, and transthoracic echocardiography, with 68 patients also undergoing transesophageal study. RESULTS: Major cardiovascular criteria from the Ghent nosology predominated in adults (P < 0.0001), minor criteria in children (P = 0.007). Among pediatric patients, 83% had a New York Heart Association (NYHA) functional class of I; however, 64% of the adult patients had an NYHA class ≥II, (P < 0.0001). Corrected aortic echocardiographic measurements of both groups demonstrated statistically significant differences. Children had a greater prevalence of mitral valve prolapse, while adults more frequently presented with aortic complications. Seven patients died during follow-up from aortic complications, one child and six adults. CONCLUSIONS: Based on the data, we can conclude that MFS in the Mestizo-Mexican population has a distinctly different clinical pattern in children and adults, and a graver prognosis in adults. Adult patients with MFS are significantly more likely, than children, to have aortic dilation, aortic aneurysm, aortic regurgitation, aneurysm rupture, aortic dissection, and fatal outcome. Children with MFS are more likely, than adults, to present with asymptomatic mitral and tricuspid prolapse and mitral valve regurgitation.

Performance levels of four Latin American laboratories for the serodiagnosis of Chagas disease in Mexican sera samples.

In nearly all of the previous multicentre studies evaluating serological tests for Trypanosoma cruzi infection, sera samples from Central or South American countries have been used preferentially. In this work we compared the reliability of the serological tests using Mexican sera samples that were evaluated in four independent laboratories. This included a reference laboratory in Brazil and three participant laboratories, including one in Central America and two in Mexico. The kappa index between Brazilian and Honduran laboratories reached 1.0 and the index for the Mexican laboratories reached 0.94. Another finding of this study was that the source of antigen did not affect the performance of the serological tests.

Association between IL-1B and IL-1RN gene polymorphisms and Chagas' disease development susceptibility.

Though it is known that the immune system exerts some influence on the resistance against T. cruzi infection its precise role in this process is not well-understood. Some IL-1B alleles and haplotypes have been associated with susceptibility to inflammatory, autoimmune and infectious diseases. The objective of this study was to determine and compare the distribution of IL-1B and IL-1 receptor antagonist (IL-1RN) polymorphisms among T. cruzi seropositive patients, patients with idiopathic dilated cardiomyopathy (IDC) and healthy individuals. We studied 86 individuals seropositive for T. cruzi (58 patients with chronic chagasic cardiomyopathy (CCC) and 28 asymptomatics), 50 seronegative individuals with IDC and 109 healthy individuals. IL-1B-511, IL-1F10.3 IL-1RN.4, IL-1RN 6/1, and IL-1RN 6/2 polymorphisms were analyzed using real-time PCR allelic discrimination technology. Infected patients presented an increased frequency of the CC genotype of the IL-1RN.4 polymorphism when compared to IDC (pC = 0.028; OR = 11.46). The C allele of this polymorphism was found increased in CCC when compared with IDC (pC = 0.036; OR = 0.5) and with controls (pC = 0.035; OR = 1.87). CC genotype of IL-1RN.4 polymorphism was increased in patients with CCC when compared to IDC (pC = 0.0018; OR = 16.74) and healthy individuals (pC = 0.011; OR = 3.6). There is an evident association between the IL1RN.4 polymorphism, T. cruzi infection and CCC development.

Performance levels of four Latin American laboratories for the serodiagnosis of Chagas disease in Mexican sera samples

In nearly all of the previous multicentre studies evaluating serological tests for Trypanosoma cruzi infection, sera samples from Central or South American countries have been used preferentially. In this work we compared the reliability of the serological tests using Mexican sera samples that were evaluated in four independent laboratories. This included a reference laboratory in Brazil and three participant laboratories, including one in Central America and two in Mexico. The kappa index between Brazilian and Honduran laboratories reached 1.0 and the index for the Mexican laboratories reached 0.94. Another finding of this study was that the source of antigen did not affect the performance of the serological tests.

Altered flow-mediated vasodilatation, low paraoxonase-1 activity, and abnormal high-density lipoprotein subclass distribution in Takayasu's arteritis.

BACKGROUND: Takayasu's arteritis (TA) is an idiopathic chronic inflammatory disease that causes occlusion of large arteries, but little is known about whether affected patients are characterized by endothelial dysfunction, different high-density lipoproteins (HDL) subclasses and paraoxonase-1 (PON1) activity. METHODS AND RESULTS: In the present study, 30 patients with TA, 30 age- and gender-matched volunteers (controls) and 15 patients with essential hypertension were studied. Flow-mediated vasodilation (FMD) and maximal blood flow velocity, assessed in the brachial artery by high-resolution ultrasound, were significantly lower in patients. HDL subclass distribution was determined by polyacrylamide gradient gel electrophoresis. HDL-cholesterol, HDL3b subclass and PON1 activity, assessed spectrophotometrically using phenylacetate as the substrate, were also lower in patients compared with controls. In a multiple regression analysis, the use of prednisone and systolic blood pressure were independent variables that predicted the FMD. CONCLUSIONS: A low FMD, abnormal size distribution of HDLs, and low PON1 activity are observed in TA patients. These abnormalities appear independently and constitute a cluster that may contribute to the vascular dysfunction of TA arteritis.

[Serum levels of antistreptolysin O in teenagers from Mexican urban and rural areas]. / Titulos séricos de antiestreptolisina O en adolescentes del area urbana y rural en México.

BACKGROUND: Antistreptolysin O (ASLO) may be an isolated evidence of recent infection by group A Streptococcus, especially in patients suspected of having a nonsuppurative sequel to this infection. We evaluated ASLO titers in students from urban and rural areas, age and geographic characteristics of study population among several other variables, could be factors that may influence in the ASLO levels in children. OBJECTIVE: To determine sera titers ofASLO in healthy adolescents from rural and urban areas in Mexico. MATERIAL AND METHODS: ASLO were detected by nephelometry, including 218 sera from asymptomatic high school students, two schools belong to government, one was at urban area (group 1; n = 68) and other was located at country side (rural) area (group 2; n = 75). The remaining school belong to private system and was located at urban area (group 3; n = 75). RESULTS: We included 218 sera, 58% were from females. Age (years) was expressed as median (maximum-minimum values) for groups 1, 2, and 3; 13 (12-18), 14 (12-18) and 14 (12-16) respectively. Weight (kg), height (cm) and body mass index (BMI) was expressed by mean +/- SD values for groups 1, 2, and 3; weight 48.8 +/- 8.8, 50.8 +/- 7.8, 57.2 +/- 11 respectively; height 154 +/- 6.9, 156 +/- 6.8, 161 +/- 8.2 and BMI 20.2 +/- 3.0, 20.9 +/- 2.9, and 21.9 +/- 3.6 respectively; when comparison among groups was performed, we found statistical differences in all variables. Titers for ASLO (UI/mL) expressed as median (maximum-minimum values) for groups 1, 2, and 3 were: 147 (20-828), 129 (25-1390) and 84 (25-848). Statistical differences between groups 1 vs 3, and 2 vs 3 were found. DISCUSSION: We confirm the variability of serum ASLO values among high school students. Thus, group 1 exhibited the highest levels of ASLO, and lowest values of weight, height, and BMI. When comparing against group 2 differences were non-significant. When comparing ASLO titers, Group 3 displayed lowest levels, which significantly differed from those of both groups 1 and 2. These findings discard influence of geographic location in ASLO titers, and indicate that better socioeconomic conditions may play a role.