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PubMed2001

Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation.

CONTEXT: Patients who have atrial fibrillation (AF) have an increased risk of stroke, but their absolute rate of stroke depends on age and comorbid conditions. OBJECTIVE: To assess the predictive value of classification schemes that estimate stroke risk in patients with AF. DESIGN, SETTING, AND PATIENTS: Two existing classification schemes were combined into a new stroke-risk scheme, the CHADS( 2) index, and all 3 classification schemes were validated. The CHADS( 2) was formed by assigning 1 point each for the presence of congestive heart failure, hypertension, age 75 years or older, and diabetes mellitus and by assigning 2 points for history of stroke or transient ischemic attack. Data from peer review organizations representing 7 states were used to assemble a National Registry of AF (NRAF) consisting of 1733 Medicare beneficiaries aged 65 to 95 years who had nonrheumatic AF and were not prescribed warfarin at hospital discharge. MAIN OUTCOME MEASURE: Hospitalization for ischemic stroke, determined by Medicare claims data. RESULTS: During 2121 patient-years of follow-up, 94 patients were readmitted to the hospital for ischemic stroke (stroke rate, 4.4 per 100 patient-years). As indicated by a c statistic greater than 0.5, the 2 existing classification schemes predicted stroke better than chance: c of 0.68 (95% confidence interval [CI], 0.65-0.71) for the scheme developed by the Atrial Fibrillation Investigators (AFI) and c of 0.74 (95% CI, 0.71-0.76) for the Stroke Prevention in Atrial Fibrillation (SPAF) III scheme. However, with a c statistic of 0.82 (95% CI, 0.80-0.84), the CHADS( 2) index was the most accurate predictor of stroke. The stroke rate per 100 patient-years without antithrombotic therapy increased by a factor of 1.5 (95% CI, 1.3-1.7) for each 1-point increase in the CHADS( 2) score: 1.9 (95% CI, 1.2-3.0) for a score of 0; 2.8 (95% CI, 2.0-3.8) for 1; 4.0 (95% CI, 3.1-5.1) for 2; 5.9 (95% CI, 4.6-7.3) for 3; 8.5 (95% CI, 6.3-11.1) for 4; 12.5 (95% CI, 8.2-17.5) for 5; and 18.2 (95% CI, 10.5-27.4) for 6. CONCLUSION: The 2 existing classification schemes and especially a new stroke risk index, CHADS( 2), can quantify risk of stroke for patients who have AF and may aid in selection of antithrombotic therapy.

Aged↗
PubMed1988

Chicken mucin-cross-reactive antigen.

We have previously described a chicken heterophile antigenic determinant (CHAD-1) shared by Mycobacterium smegmatis and chicken tissues. We then demonstrated that CHAD-1 is present on several chicken glycoproteins and that its immunoreactive domains are highly branched asparagine-linked oligosaccharides terminating in N-acetylglucosamine residues. In the present study, we have shown that CHAD-1 is also expressed by mucin purified to homogeneity from a soluble mucus of chicken intestine. Another antigen found on chicken mucin is a chicken mucin-cross-reactive antigen (CMCRA). Antisera to this antigen were produced by immunization of rabbits with an enriched preparation of CHAD-1 isolated from the bursa of Fabricius. These antisera were absorbed with Mycobacterium smegmatis (to block the anti-CHAD-1 antibody) and with chicken serum, and then used for immunoperoxidase staining of chicken tissue sections for CMCRA. The latter antigen was detected in most medullary cells of the bursa, in epithelial cells and Hassal's corpuscles of the thymus, and in mucus-producing cells of the intestine, esophagus, trachea, and bronchi. Using Western immunoblot analysis, we demonstrated that CMCRA is expressed by a number of polypeptides extracted from bursal lymphoid cells. These polypeptides could not be detected in extracts of thymus, spleen, peripheral blood or bone marrow mononuclear cells.

Animals↗
PubMed2006

Additive role of plasma von Willebrand factor levels to clinical factors for risk stratification of patients with atrial fibrillation.

BACKGROUND AND PURPOSE: To aid decisions for thromboprophylaxis in atrial fibrillation (AF), several risk stratification schemes that predict stroke risk according to clinical and echocardiographic features have been published. von Willebrand factor (vWf) is a plasma markers of endothelial damage/dysfunction and is associated with the risk of stroke and vascular events in AF patients. This study determined the additive role of plasma vWf levels to clinical factors for risk stratification in patients with AF. METHODS: We classified 994 AF patients who were enrolled in the SPAF III trial as being at low, moderate, or high risk of stroke and thromboembolism according to the Birmingham and CHADS(2) risk stratification schemes. vWf levels were classified as elevated when >or=158 IU /dL. Rates of ischemic stroke and vascular events within each clinical risk stratum with and without plasma vWf levels were compared. RESULTS: The accuracy of both clinical risk stratification schemes was similar for predicting event rates (Birmingham: ischemic strokes, 0.642; vascular events, 0.670; CHADS(2): ischemic strokes, 0.672; vascular events, 0.672). Subsequent addition of categorized vWf levels to both clinical risk stratification schemes further refined risk stratification for stroke and vascular events. When added to the Birmingham and CHADS(2) clinical risk stratification, high vWf levels were independently associated with a risk of vascular events (hazard ratio, 2.05; 95% confidence interval, 1.30 to 3.22 and 2.01, 1.27 to 3.18 with Birmingham and CHADS(2), respectively) but not ischemic stroke. CONCLUSIONS: When added to clinical risk stratification schemes (Birmingham; CHADS(2)), plasma vWf levels refined clinical risk stratification for stroke and vascular events among AF patients. vWf levels may aid decisions about thromboprophylaxis, particularly among AF patients at moderate risk.

Aged↗
PubMed1987

Identification of terminal N-acetylglucosamine residues of highly branched asparagine-linked oligosaccharides as immunoreactive domains of a chicken heterophile antigenic determinant.

Chicken heterophile antigenic determinant (CHAD-1) has been previously found in medullary lymphocytes of the bursa and thymus as well as in some non-lymphoid cells by the immunoperoxidase method, using rabbit antiserum to a complete Freund's adjuvant (CFA) as the first antibody. In this work we demonstrated that absorption of anti-CFA serum with highly purified preparations of hen egg white glycoproteins (ovomucoid, ovoinhibitor, ovalbumin) or chicken orosomucoid completely blocked immunoperoxidase staining for CHAD-1. Treatment of these glycoproteins with beta-N-acetylglucosaminidase suppressed their capacity to inhibit this staining. Absorption of anti-CFA serum with asparagine-linked glycopeptides which have the mannose alpha 1,3 arm disubstituted by GlcNAc residues and which have another GlcNAc residue linked beta 1,4 to the beta-linked mannose of the core also inhibited staining for CHAD-1. These data indicated that highly branched asparagine-linked oligosaccharides with terminal GlcNAc residues beta-linked to mannose represent immunoreactive domains of CHAD-1.

Absorption↗
PubMedDate not supplied

The national exposure research laboratory's consolidated human activity database.

EPA's National Exposure Research Laboratory (NERL) has combined data from 12 U.S. studies related to human activities into one comprehensive data system that can be accessed via the Internet. The data system is called the Consolidated Human Activity Database (CHAD) and is available at http:// www.epa.gov/nerl/. CHAD contains 22,968 person days of activity and is designed to assist exposure assessors and modelers in constructing population "cohorts" of people with specified characteristics that are suitable for subsequent analysis or modeling. This paper describes the studies comprising CHAD and the various intellectual foundations that underlay the gathering of human activity pattern data. Next, it provides a brief overview of the Internet version of CHAD, and discusses how the program was formulated. Emphasis is placed on how activity-specific energy expenditure estimates were developed. Finally, the paper recommends steps that should be taken to improve the collection of activity data that would improve energy expenditure estimates and related information needed for physiologically based exposure dose modeling efforts.

Activities of Daily Living↗
PubMed2005

Differences among clinical classification schemes for predicting stroke in atrial fibrillation: implications for therapy in daily practice.

BACKGROUND: Several clinical classification schemes (CCSs) for predicting stroke in nonvalvular atrial fibrillation (NVAF) have been developed to help identify patients eligible for anticoagulation. OBJECTIVES: To estimate the agreement in predicting the risk of stroke among four widespread CCSs, and to determine their implications for thromboprophylaxis in clinical practice. METHODS: The authors conducted a prospective, multicenter, observational study of adults with NVAF in 12 emergency departments (EDs) in July 2000 and February 2001. The proportions of patients classified as having high, moderate, and low risk of stroke among the following CCSs were compared: the Atrial Fibrillation Investigators (AFI), the Stroke Prevention in Atrial Fibrillation (SPAF), the CHADS(2) (an acronym for congestive heart failure, hypertension, age >75 years, diabetes mellitus, and prior stroke or transient ischemic attack), and the American College of Chest Physicians (ACCP). RESULTS: One thousand two hundred twenty patients were included. The proportions of patients stratified as having high/moderate/low risk of stroke according to each CCS were: 70%/22%/8% (AFI), 38%/41%/21% (SPAF), 13%/45%/42% (CHADS(2)), and 86%/7%/7% (ACCP). The agreement was medium between AFI and ACCP (kappa = 0.52) and poor among the rest of them (AFI/SPAF, kappa = 0.01; AFI/CHADS(2), kappa = 0.02; SPAF/CHADS(2), kappa = 0.18; SPAF/ACCP, kappa = 0.11; CHADS(2)/ACCP, kappa = 0.03). The agreements in selecting patients as eligible for antiplatelet therapy or anticoagulation were: AFI/SPAF, kappa = 0.45; AFI/CHADS(2), kappa = 0.22; AFI/ACCP, kappa = 0.91; SPAF/CHADS(2), kappa = 0.47; SPAF/ACCP, kappa = 0.11; CHADS(2)/ACCP, kappa = 0.03. CONCLUSIONS: In the ED population studied, these CCSs showed relevant differences in the risk of stroke stratification and, therefore, in the identification of patients with NVAF eligible for anticoagulation.

Aged↗
PubMed1996

Short report: polymerase chain reaction detection of hepatitis E virus in north African fecal samples.

Epidemics of enterically-transmitted non-A, non-B hepatitis were described in 1983-1984 involving French soldiers in Chad and in 1979-1980 in residents of Algeria. Hepatitis E virus (HEV) was subsequently implicated by serology. In this study, the presence of HEV in patient stool specimens from both outbreaks and from sporadic cases in residents of Chad (1994) was documented. This virus was detected in fecal suspensions by antibody capture of the virus and reverse transcriptase-polymerase chain reaction amplification of the viral RNA in the 3' end of open reading frame 2. Two of five epidemic cases from Chad (1983-1984) were positive, as well as one of five sporadic cases from Chad (1994), and two of three epidemic cases from Algeria (1979-1980). Of these 13 patients, 12 had detectable anti-HEV IgG in their serum. These results confirmed that HEV was the cause of hepatitis in at least five of these 13 patients.

Africa, Northern↗
PubMed1998

Experimental African HEV infection in cynomolgus macaques (Macaca fascicularis).

Experimental infection with hepatitis E virus (HEV) from Africa has not been investigated. Our purpose was to study hepatitis E produced by HEV from Chad (North Africa) and to analyze the genetic sequence of the HEV obtained after animal passage. An HEV-containing fecal sample from Chad was intravenously inoculated in four cynomolgus macaques. When serum Alanine Amino Transferase (ALT) levels rose, open liver biopsy and bile aspiration were performed. In all the monkeys, an ALT rise occurred 25 to 32 days after inoculation and new anti-HEV was detected by Enzyme Immuno Assay (EIA). Hepatic histopathology was consistent with acute viral hepatitis. HEV was detected by polymerase chain reaction (PCR) in bile (3/4 animals) and feces (2/4 animals) and by imunoelectron microscopy (IEM) in the inoculum and one bile specimen. A genetic variant HEV was identified in one monkey. The Chad HEV produced hepatitis E with pathophysiologic and histopathologic findings similar to those observed with HEV from other geographic origins. A genomic variant HEV population was produced after one passage in a macaque.

Alanine Transaminase↗
PubMed1996

A predictable comeback: the second pandemic of infections caused by Neisseria meningitidis serogroup A subgroup III in Africa, 1995.

Between 14 January and 4 April 1995 we isolated and characterized 44 meningococcal strains in Cameroon, Chad, Niger, and Burkina Faso; among these was the strain A:4:P1.9/clone III-1, which was involved in the second meningitis pandemic. This isolate was found in the clonal form in Niger and strains of the ET-37 complex were also found in the other three study countries, but apparently did not cause epidemics. One strain (Y:2a:P1.2,5 (ET-37 complex)) was isolated in January 1995 and another (A:4:P1.9) in March 1995 in Garoua (Cameroon). Eight strains were isolated in Moundou (Chad) between January and April 1995: the A:4:P1.9/clone III-1 (1 strain); members of the ET-37 complex (Y:2a:P1.2,5 (4 strains), Y:NT:P1.2,5 (1 strain), and Y:2a:-(1 strain)); and serogroup X (1 strain). In Niger, 31 strains were isolated between February and April 1995 from different regions. All were A:4:P1.9/clone III-1; between November 1994 and April 1995 there were 23814 cases of meningitis reported of which 2227 resulted in death. Three strains were isolated in Burkina Faso in April 1995: two were Y:2a:P1.2,5 (ET-37 complex) and one was A:4:P1.9/clone III-1. Thus in 1995 the epidemic and invasive strain (A:4:P1.9/clone III-1) responsible for the second pandemic was present in the four countries (Cameroon, Chad, Niger and Burkino Faso) that make up the area frequently affected by such epidemics and where cases are generally reported during the dry season.

Adolescent↗
PubMedDate not supplied

Gaussian pulse decomposition: an intuitive model of electrocardiogram waveforms.

This study presents a novel approach to modeling the electrocardiogram (ECG): the Gaussian pulse decomposition. Constituent waves of the ECG are decomposed into and represented by Gaussian pulses using an iterative algorithm: the chip away decomposition (ChAD) algorithm. At each iteration, a nonlinear minimization method is used to fit a portion of the ECG waveform with a single Gaussian pulse, which is then subtracted from the ECG waveform. The process iterates on the resulting residual waveform until the normalized mean square error is below an acceptable level. Three different minimization methods were compared for their applicability to the ChAD algorithm; the Nelder-Mead simplex method was found to be more noise-tolerant than the Newton-Raphson method or the steepest descent method. Using morphologically different ECG waveforms from the MIT-BIH arrhythmia database, it was demonstrated that the ChAD algorithm is capable of modeling not only normal beats, but also abnormal beats, including those exhibiting a depressed ST segment, bundle branch block, and premature ventricular contraction. An analytical expression for the spectral contributions of the constituent waves was also derived to characterize the ECG waveform in the frequency domain. The Gaussian pulse model, providing an intuitive representation of the ECG constituent waves by use of a small set of meaningful parameters, should be useful for various purposes of ECG signal processing, including signal representation and pattern recognition.

Algorithms↗
PubMed2006

A comparison of girls' and boys' aggressive-disruptive behavior trajectories across elementary school: prediction to young adult antisocial outcomes.

Multiple group analysis and general growth mixture modeling was used to determine whether aggressive- disruptive behavior trajectories during elementary school, and their association with young adulthood antisocial outcomes, vary by gender. Participants were assessed longitudinally beginning at age 6 as part of an evaluation of 2 school-based preventive programs. Two analogous trajectories were found for girls and boys: chronic high aggression- disruption (CHAD) and stable low aggression- disruption (LAD). A 3rd class of low moderate aggression- disruption (LMAD) for girls and increasing aggression- disruption (IAD) for boys also was found. Girls and boys in analogous CHAD classes did not differ in trajectory level and course, but girls in the CHAD and LAD classes had lower rates of antisocial outcomes than boys. Girls with the LMAD trajectory differed from boys with the IAD trajectory.

Achievement↗
PubMed2000

Cold haemagglutinin disease: clinical significance of serum haemolysins.

Two hundred and twenty-one patients with cold haemagglutinins of thermal amplitude > or = 30 degrees C (considered to be a reasonable indicator of clinical significance) were classified by in vitro haemolysin activity into three groups. Group 1 contained 116 individuals in whom haemolysins were never detected; the 74 patients in Group 2 had monophasic haemolysins alone; whereas both monophasic and biphasic haemolysins were detected in the 31 Group 3 patients. There was a significantly higher proportion of patients in Groups 2 and 3 with haptoglobin levels < 0.1 g/l compared with Groups 1 and 2, respectively (P < 0.005 and P < 0.001). Direct antiglobulin test results showed that the autoimmune response became more complex and IgM predominant through Groups 1-3, resulting in an increasing ability to activate complement which was reflected in increasing haemolysin activity and number of patients with active haemolysis. The 31 patients in Group 3 were mostly elderly (median age 71 years at presentation) and the majority had chronic cold haemagglutinin disease (CHAD), several in association with lymphoid neoplasms or carcinomas; only four had acute CHAD. The natural history of idiopathic chronic CHAD was of mild, well compensated haemolysis, punctuated by severe acute episodes necessitating intensive therapy. The condition often remained active for long periods and did not appear to affect natural lifespan. In some cases, no treatment (or just warmth) was needed; in others continuous or intermittent prednisolone and/or chlorambucil were effective; yet others required a greater variety and more intense therapy, or treatment of associated conditions. Blood transfusion support was frequently required when haemolysis was severe.

Adolescent↗
PubMed2004

Does discussion of family planning improve knowledge of partner's attitude toward contraceptives?

CONTEXT: Results from an analysis of 1998 Demographic and Health Survey (DHS) data from Kenya, where the approval rate of family planning is 90%, have cast doubt on the assumption that spousal discussion improves knowledge of partner's attitude toward family planning. However, it is not known whether this finding also applies to contexts more typical of Sub-Saharan Africa, where approval is not as high. METHODS: DHS data from 21 Sub-Saharan African countries were used to assess the relationship between spousal discussion and correct reporting of partner's attitude toward family planning. Multivariate analyses of data from Chad were conducted to further examine this relationship in a setting where contraceptive approval was not high. RESULTS: In every country, the proportion of women correctly reporting their spouse's disapproval of contraception was smaller among those who had discussed family planning with their husband than among those who had never done so. However, in an analysis of Chad data that included women who did not know their husband's attitude toward contraception, proportions of women correctly citing their husband's attitude were larger if discussion had occurred than if it had not, regardless of the husband's actual approval status. In multivariate analyses of Chad data that controlled for women's demographic characteristics, discussion was positively associated with correct reporting of husband's approval, but negatively associated with correct reporting of his disapproval. CONCLUSIONS: Partner discussion does not necessarily mean an increase in knowledge of a partner's contraceptive attitudes. Therefore, anticipated reductions in unmet need for contraception through improvements in spousal discussion may be overstated.

Adult↗
PubMed2006

A deficiency in the region homologous to human 17q21.33-q23.2 causes heart defects in mice.

Several constitutional chromosomal rearrangements occur on human chromosome 17. Patients who carry constitutional deletions of 17q21.3-q24 exhibit distinct phenotypic features. Within the deletion interval, there is a genomic segment that is bounded by the myeloperoxidase and homeobox B1 genes. This genomic segment is syntenically conserved on mouse chromosome 11 and is bounded by the mouse homologs of the same genes (Mpo and HoxB1). To attain functional information about this syntenic segment in mice, we have generated a 6.9-Mb deletion [Df(11)18], the reciprocal duplication [Dp(11)18] between Mpo and Chad (the chondroadherin gene), and a 1.8-Mb deletion between Chad and HoxB1. Phenotypic analyses of the mutant mouse lines showed that the Dp(11)18/Dp(11)18 genotype was responsible for embryonic or adolescent lethality, whereas the Df(11)18/+ genotype was responsible for heart defects. The cardiovascular phenotype of the Df(11)18/+ fetuses was similar to those of patients who carried the deletions of 17q21.3-q24. Since heart defects were not detectable in Df(11)18/Dp(11)18 mice, the haplo-insufficiency of one or more genes located between Mpo and Chad may be responsible for the abnormal cardiovascular phenotype. Therefore, we have identified a new dosage-sensitive genomic region that may be critical for normal heart development in both mice and humans.

Animals↗
PubMed2003

[A retrospective clinical study of chronic high altitude disease complicated by acute exacerbation in high altitude environment].

OBJECTIVE: To study chronic high altitude disease (CHAD) with concurrent acute high altitude disease (AHAD) in regions of high altitude. METHODS: 18,090 inpatients from Feb. 1956 to Dec. 1995 conforming to a screening standard were observed in a hospital located at altitude 3658 m. 1,028 inpatients suffering from CHAD when hospitalized were collected as a study group. 17,020 inpatients suffering from non-HAD when first hospitalized served as a control group. The morbidity rate of AHAD in these two groups in a follow-up period of 1 - 20 years was analyzed. RESULTS: (1) AHAD morbidity rate was increasing with prolongation of observation time in the control group, but it was not so in the study group. Annual and accumulative morbidity of AHAD in the study group was obviously higher than that in the control group (P < 0.005, OR = 5.03, RR = 4.33). (2) The morbidity rates of three types of AHAD aside from high altitude pulmonary edema (HAPE) of high altitude hypertension (HAH) group and high altitude cerebral edema (HACE) of high altitude heart disease (HAHD) group was obviously higher in the study group than in the control (P < 0.05 - 0.005). AHAD morbidity rate in HAHD group and Monge's disease was 23.5% and 22.0% (OR = 7.33 - 6.71, RR = 5.86 - 5.47). (3) AHAD morbidity rate in HAHD group and Monge's disease group was obviously higher than that in the control, constituting mainly a high morbidity of mild acute high altitude disease. CONCLUSION: The risk of AHAD increases about 5-fold in CHAD patients than in the multitude of high altitude acclimatization, being most evident in HAHD and Monge's disease.

Acute Disease↗
PubMed1982

Lymphoma in primary chronic cold hemagglutinin disease treated with chlorambucil.

Two patients with primary chronic cold hemagglutinin disease (CHAD) were treated with chlorambucil for ten and 7 1/2 years, with cumulative doses of 14 and 6.6 g, respectively. Both responded favorably, and malignant lymphoma eventually developed in both of them. An attempt to assess the incidence of lymphoma as part of the natural course of untreated CHAD failed for want of proof. Literature since 1970 reported no chlorambucil-associated lymphoma. Of 77 responses to a questionnaire mailed to 135 US hematology-oncology programs, 76 reported no examples of chlorambucil-associated lymphoma. One response, however, did relate that diffuse histiocytic lymphoma developed in three of 141 patients receiving prolonged chlorambucil therapy for polycythemia vera. Alkylating-agent therapy for CHAD might be associated with development of lymphoma.

Anemia, Hemolytic, Autoimmune↗
PubMed1997

Clinical, biochemical, and morphologic investigations of a case of long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency.

We report the premortem and postmortem morphologic and histologic features and biochemical findings of a patient with long-chain 3-hydroxyacyl-CoA dehydrogenase (L-CHAD) deficiency and compare these with those described in previously reported cases of L-CHAD deficiency. In addition to chronic nonketotic hypoglycemia, hypotonia, and liver failure, this patient had chronic hemolytic anemia and delayed central nervous system myelination. These features have not been previously documented in L-CHAD deficiency.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2004

Respiratory infections: SARS and tuberculosis.

Positive-microscopy TB is a real issue for the respiratory diseases department of N'Djaména General Hospital, with a prevalence rate of 37 cases in 100 patients. The delay of diagnosis for positive-microscopy TB is excessive. Patients seem to be more responsible for this delay than the healthcare facilities. The factors that delay treatment of TB in N'Djaména are that (1) TB diagnosis in peripheral hospitals lengthens physician delay, and (2) seeking initial treatment outside conventional medicine lengthens patient delay. The following recommendations arise from this study: For the public health ministry: Reboost the national program against TB in Chad. Increase personnel in the respiratory diseases department at the N'Djaména General Hospital. Provide refresher TB education to care providers, stressing the importance of communication with the patient. For the national program against TB in Chad: Initiate a public information, education, and communication campaign about TB. Implement use of DOTS nationwide. For physicians increase communication with patients.

Chad↗