Standard Examination System for Laparoscopy in Penetrating Abdominal Trauma

Background: The high missed occult small bowel injuries (SBI) associated with laparoscopy in trauma (LIT) is a major reason why some surgeons still preclude LIT today. No standardized laparoscopic examination for evaluation of the peritoneal cavity is described for trauma. The objective of this article is to verify if a systematic standardized laparoscopic approach could correctly identify SBI in the peritoneal cavity for penetrating abdominal trauma (PAT). Methods: Victims with PAT were evaluated in a prospective, nonrandomized study. A total of 75 hemodynamically stable patients with suspected abdominal injuries were operated by LIT and converted to laparotomy if criteria were met: SBI and lesions to blind spot zones-retroperitoneal hematoma, injuries to segments VI or VII of the liver, or injuries to the posterior area of the spleen. Inclusion criteria were equivocal evidence of abdominal injuries or peritonea] penetration; systolic blood pressure >90 mm Hg and <3 L of IV fluids in the first hour of admission; Glasgow Coma Scale score >12; and age >12 years. Exclusion criteria were back injuries; pregnancy; previous laparotomy; and chronic cardiorespiratory disease. Results: Sixty patients were males and there were 38 stab wounds and 37 gunshot wounds. No SBI was missed, but a pancreatic lesion was undiagnosed due to a retroperitoneal hematoma. Twenty patients (26.6%) were converted. Unnecessary laparotomies were avoided in 73.33%. Therapeutic LIT was possible in 22.7%. Accuracy was 98.66% with 97.61% sensitivity and 100% specificity. Conclusions: Standard systematic laparoscopic exploration was 100% effective to detect SBI in the peritoneal cavity. Conversion from LIT to laparotomy should be done if injuries to blind spot zones are found which are poorly evaluated by LIT. Therapeutic LIT is feasible in PAT.

Impact of Stent-Graft Oversizing on the Thoracic Aorta: Experimental Study in a Porcine Model

Purpose: To analyze in an experimental animal model the effect of 4 different levels of stents-graft oversizing on non-atherosclerotic aortas such as those found in young individuals who undergo stent-graft repair for traumatic aortic injuries. Methods: The diameter of the porcine thoracic aorta is similar to the aorta of young adults (18-20 mm), so 25 pigs were randomized into 5 groups: 1 control (without stent-graft) and 4 oversizing groups (A: 10%-19%, B: 20%-29%, C: 30%-39%, and D: >40%). Two types of biomechanical tests were performed on all aortas 4 weeks after endoprosthesis deployment. Results: The results of the detachment test, which analyzed the strength necessary to remove the stent-graft from the aorta, were similar in the 4 groups (A: 42 N, B: 41 N, C: 46 N, and D: 46 N). However, 2 aortas ruptured during the tests (groups C and D). The second test was performed in 3 aortic segments. Maximum shear strength, maximum stress, and maximum tension supported by the aortic wall had a negative and linear correlation with oversizing. There were significant differences in all 4 groups when compared with the control group. Strain, which reflects the elastic properties of the aortic wall, was very similar in all 4 groups, but a great difference was found when compared with the control group (p<0.0001). Conclusion: The study showed an important subacute change in the biomechanical properties of the aortic wall after implantation of an oversized endoprosthesis. This weakness of the aortic wall was confirmed by 2 ruptures during the detachment test. These results partially explain the interaction of stent-grafts with non-atherosclerotic thoracic aortas and may serve as a basis for further studies and the development of specific material to be used in vascular trauma and young patients. J Endovasc Ther. 2011; 18: 576-584

Race modeling: An effective cognitive strategy for the 100 m sprinter?

The purpose of this study was to investigate the effects of a specific cognitive race plan on 100 m sprint performance, Twelve elite sprinters (11 male and 1 female) performed 100 m time trials under normal (control) conditions and then under experimental conditions (use of race cues). In the experimental condition, participants were asked to think about specific thought content in each of three segments of the 100 m. A multiple baseline design was employed. A mean improvement of 0.26 s was found. Eleven of the 12 participants showed improvement using the specific cognitive race plan (p < .005). Participants also produced more consistent sprint performances when using the cues (p < .01). Subjective evaluations made by the participants unanimously supported the use of the race plan for optimizing sprint performance. Environmental conditions, effort, and practice effects were considered as possible influences on the results.

Biliary and pancreatic dysgenesis in mice harboring a mutation in Pkhd1

Autosomal recessive polycystic kidney disease is a hereditary fibrocystic disease that involves the kidneys and the biliary tract. Mutations in the PKHD1 gene are responsible for typical forms of autosomal recessive polycystic kidney disease. We have generated a mouse model with targeted mutation of Pkbd1 by disrupting exon 4, resulting in a mutant transcript with deletion of 66 codons and expression at similar to 30% of wild-type levels. Pkhd1(del4/d3l4) mice develop intrahepatic bile duct proliferation with progressive cyst formation and associated periportal fibrosis. In addition, these mice exhibit extrahepatic manifestations, including pancreatic cysts, splenomegaly, and common bile duct dilation. The kidneys are unaffected both histologically and functionally. Fibrocystin is expressed in the apical membranes and cilia of bile ducts and distal nephron segments but is absent from the proximal tubule. This pattern is unchanged in orthologous models of autosomal dominant polycystic kidney disease due to mutation in Pkd1 or Pkd2. Mutant fibrocystin in Pkhd1(del4/d3l4) mice also retains this expression pattern. The hypomorphic Pkhd1(del4/d3l4) mouse model provides evidence that reduced functional levels of fibrocystin are sufficient for cystogenesis and fibrosis in the liver and pancreas, but not the kidney, and supports the hypothesis of species-dependent differences in susceptibility of tissues to Pkbdl mutations.

Qualitative and Quantitative Real Time Myocardial Contrast Echocardiography for Detecting Hibernating Myocardium

Background: Real time myocardial contrast echocardiography (RTMCE) is an emerging imaging modality for assessing myocardial perfusion that allows for noninvasive quantification of regional myocardial blood flow (MBF). Aim: We sought to assess the value of qualitative analysis of myocardial perfusion and quantitative assessment of myocardial blood flow (MBF) by RTMCE for predicting regional function recovery in patients with ischemic heart disease who underwent coronary artery bypass grafting (CABG). Methods: Twenty-four patients with coronary disease and left ventricular systolic dysfunction (ejection fraction < 45%) underwent RTMCE before and 3 months after CABG. RTMCE was performed using continuous intravenous infusion of commercially available contrast agent with low mechanical index power modulation imaging. Viability was defined by qualitative assessment of myocardial perfusion as homogenous opacification at rest in >= 2 segments of anterior or >= 1 segment of posterior territory. Viability by quantitative assessment of MBF was determined by receiver-operating characteristics curve analysis. Results: Regional function recovery was observed in 74% of territories considered viable by qualitative analysis of myocardial perfusion and 40% of nonviable (P = 0.03). Sensitivity, specificity, positive and negative predictive values of qualitative RTMCE for detecting regional function recovery were 74%, 60%, 77%, and 56%, respectively. Cutoff value of MBF for predicting regional function recovery was 1.76 (AUC = 0.77; 95% CI = 0.62-0.92). MBF obtained by RTMCE had sensitivity of 91%, specificity of 50%, positive predictive value of 75%, and negative predictive value of 78%. Conclusion: Qualitative and quantitative RTMCE provide good accuracy for predicting regional function recovery after CABG. Determination of MBF increases the sensitivity for detecting hibernating myocardium. (Echocardiography 2011;28:342-349).

Early Increase in Myocardial Perfusion After Stem Cell Therapy in Patients Undergoing Incomplete Coronary Artery Bypass Surgery

Incomplete revascularization is associated with worse long-term outcomes. Autologous bone marrow cells (BMC) have recently been tested in patients with severe coronary artery disease. We tested the hypothesis that intramyocardial injection of autologous BMC increases myocardial perfusion in patients undergoing incomplete coronary artery bypass grafting (CABG). Twenty-one patients (19 men), 59 +/- 7 years old, with limiting angina and multivessel coronary artery disease (CAD), not amenable to complete CABG were enrolled. BMC were obtained prior to surgery, and the lymphomonocytic fraction separated by density gradient centrifugation. During surgery, 5 mL containing 2.1 +/- 1.3 x 10(8) BMC (CD34+ = 0.8 +/- 0.3%) were injected in the ischemic non-revascularized myocardium. Myocardial perfusion was assessed by magnetic resonance imaging (MRI) at baseline and 1 month after surgery. The increase in myocardial perfusion was compared between patients with < 50% (group A, n = 11) with that of patients with > 50% (group B, n = 10) of target vessels (stenosis a parts per thousand yenaEuro parts per thousand 70%) successfully bypassed. Injected myocardial segments included the inferior (n = 12), anterior (n = 7), and lateral (n = 2) walls. The number of treated vessels (2.3 +/- 0.8) was significantly smaller than the number of target vessels (4.2 +/- 1.0; P < 0.0001). One month after surgery, cardiac MRI showed a similar reduction (%) in the ischemic score of patients in group A (72.5 +/- 3.2), compared to patients in group B (78.1 +/- 3.2; P = .80). Intramyocardial injection of autologous BMC may help increase myocardial perfusion in patients undergoing incomplete CABG, even in those with fewer target vessels successfully treated. This strategy may be an adjunctive therapy for patients suffering from a more advanced (diffuse) CAD not amenable for complete direct revascularization.

Sequential Changes of Longitudinal and Radial Myocardial Deformation Indices in the Healthy Neonate Heart

Background: Significant hemodynamic changes, including preload and afterload modifications, occur during the transition from the fetal to the neonatal environment. The ductus arteriosus closes, pulmonary vascular resistance decreases, and pulmonary blood flow increases. Strain rate (SR) and strain (e) have been proposed as ultrasound indices for quantifying regional wall deformation. This study was designed to determine if these indices can detect variations in regional deformation between early and late neonatal periods. Methods: Data were obtained from 30 healthy neonates (15 male). The initial study was performed at a mean age of 20.1614 hours (exam 1) and the second at 31.962.9 days (exam 2). Apical and parasternal views were used to quantify regional left ventricular (LV) and right ventricular (RV) longitudinal and radial SR and e, and systolic, early, and late diastolic values were calculated from these curves. A paired-samples t test was performed comparing the two groups. Results: Compared with exam 1, LV radial deformation showed significant reductions in peak systolic e in the basal and mid segments (51615% vs 4669%, P < .01). LV longitudinal deformation behaved similarly, showing significant peak systolic e reductions in all measured segments. Systolic SR showed reductions only in the basal and apical segments of the lateral wall and in the mid portion of the inferior wall (-1.9 +/- 0.5 vs -1.7 +/- 0.3 s(-1) and -1.9 +/- 0.4 vs -1.7 +/- 0.2 s(-1), respectively, P = .03). RV longitudinal free and inferior wall systolic SR and e values were significantly higher in exam 2. Conclusions: LV peak systolic e decreases in exam 2 were possibly due to afterload increase and preload decrease. The lower RV initial deformation indices could be attributed to increased afterload caused by physiologic pulmonary hypertension or immature RV contractile properties. SR seemed to be a more robust index than e and less influenced by preload and afterload hemodynamic alteration. (J Am Soc Echocardiogr 2010;23:294-300.)

The role of xenobiotic metabolizing enzymes in arylamine toxicity and carcinogenesis: Functional and localization studies

In both animal models and humans, the first and obligatory step in the activation of arylamines is N-hydroxylation. This pathway is primarily mediated by the phase-I enzymes CYP1A1, CYP1A2 and CYP4B1. In the presence of flavonoids such as alpha-naphthoflavone and flavone, both CYP3A4 and CYP3A5 have also been shown to play a minor role in the activation of food-derived heterocyclic amines. The further activation of N-hydroxyarylamines by phase-II metabolism can involve both N,O-acetylation and N,O-sulfonation catalyzed by N-acetyltransferases (NAT1 and NAT2) and sulfotransferases, respectively. Using an array of techniques, we have been unable to detect constitutive CYP1A expression in any segments of the human gastrointestinal tract. This is in contrast to the rabbit where CYP1A1 protein was readily detectable on immunoblots in microsomes prepared from the small intestine. In humans, CYP3A3/3A4 expression was detectable in the esophagus and all segments of the small intestine. Northern blot analysis of eleven human colons showed considerable heterogeneity in CYP3A mRNA between individuals, with the presence of two mRNA species in same subjects. Employing the technique of hybridization histochemistry (also known as in situ hybridization), CYP4B1 expression was observed in some human colons but not in the liver or the small intestine. Hybridization histochemistry studies have also demonstrated variable NAT1 and NAT2 expression in the human gastrointestinal tract. NAT1 and NAT2 mRNA expression was detected in the human liver, small intestine, colon, esophagus, bladder, ureter, stomach and lung. Using a general aryl sulfotransferase riboprobe (HAST1), we have demonstrated marked sulfotransferase expression in the human colon, small intestine, lung, stomach and liver. These studies demonstrate that considerable variability exists in the expression of enzymes involved in the activation of aromatic amines in human tissues. The significance of these results in relation to a role for heterocyclic amines in colon cancer is discussed.

Quantification of Regional Left and Right Ventricular Deformation Indices in Healthy Neonates by Using Strain Rate and Strain Imaging

Background: Color Doppler myocardial imaging (CDMI) allows the calculation of local longitudinal or radial strain rate (SR) and strain (epsilon). The aims of this study were to determine the feasibility and reproducibility of longitudinal and radial SR and epsilon in neonates during the first hours of life and to establish reference values. Methods: Data were obtained from 55 healthy neonates (29 male; mean age, 20 +/- 14 hours; mean birth weight, 3,174 +/- 374 g). Apical and parasternal views quantified regional longitudinal and radial SR and epsilon in differing ventricular wall segments. Values at peak systole, early diastole, and late diastole were calculated from the extracted curves. CDMI data acquired at 300 +/- 50 frames/s were analyzed offline. Three consecutive cardiac cycles were measured during normal respiration. The timing of specific systolic or diastolic regional events was determined. Multiple comparisons between walls and segments were made. Results: Left ventricular (LV) longitudinal deformation showed basal differences compared with apical segments within one specific wall. Right ventricular (RV) longitudinal deformation was not homogeneous, with significant differences between basal and apical segments. Longitudinal 3 values were higher in the RV free basal and middle wall segments compared with the left ventricle. In the RV free wall apical segment, longitudinal SR and 3 were maximal. LV systolic SR and epsilon values were higher radially compared with longitudinally (radial peak systolic SR midportion, 2.9 +/- 0.6 s(-1); radial peak systolic epsilon 53.8 +/- 19%; longitudinal peak systolic SR midportion, -1.8 +/- 0.5 s(-1); longitudinal peak systolic epsilon, -24.8 +/- 3%; P < .01). Longitudinal systolic epsilon and SR interobserver variability values were 1.2% and 0.7%, respectively. Conclusion: Ultrasound-based SR and 3 imaging is a practical and reproducible clinical technique in neonates, allowing the calculation of regional longitudinal and radial deformation in RV and LV segments. These regional SR and epsilon indices represent new, noninvasive parameters that can quantify normal neonate regional cardiac function. Independent from visual interpretation, they can be used as reference values for diagnosis in ill neonates. (J Am Soc Echocardiogr 2009;22:369-375.)

Molecular Characterization, Distribution, and Dynamics of Hepatitis C Virus Genotypes in Blood Donors in Colombia

Hepatitis C virus (HCV) is a frequent cause of acute and chronic hepatitis and a leading cause for cirrhosis of the liver and hepatocellular carcinoma. HCV is classified in six major genotypes and more than 70 subtypes. In Colombian blood banks, serum samples were tested for anti-HCV antibodies using a third-generation ELISA. The aim of this study was to characterize the viral sequences in plasma of 184 volunteer blood donors who attended the ""Banco Nacional de Sangre de la Cruz Roja Colombiana,`` Bogota, Colombia. Three different HCV genomic regions were amplified by nested PCR. The first of these was a segment of 180 bp of the 5`UTR region to confirm the previous diagnosis by ELISA. From those that were positive to the 5`UTR region, two further segments were amplified for genotyping and subtyping by phylogenetic analysis: a segment of 380 bp from the NS5B region; and a segment of 391 bp from the E1 region. The distribution of HCV subtypes was: 1b (82.8%), 1a (5.7%), 2a (5.7%), 2b (2.8%), and 3a (2.8%). By applying Bayesian Markov chain Monte Carlo simulation, it was estimated that HCV-1b was introduced into Bogota around 1950. Also, this subtype spread at an exponential rate between about 1970 to about 1990, after which transmission of HCV was reduced by anti-HCV testing of this population. Among Colombian blood donors, HCV genotype 1b is the most frequent genotype, especially in large urban conglomerates such as Bogota, as is the case in other South American countries. J. Med. Virol. 82: 1889-1898, 2010. (C) 2010 Wiley-Liss, Inc.

Intestinal mucosa-associated microflora in ulcerative colitis patients before and after restorative proctocolectomy with an ileoanal pouch

PURPOSE: This study was designed to identify the mucosa-associated microflora in patients with severe ulcerative colitis before and after restorative proctocolectomy with ileoanal pouch construction in comparison with historic controls. METHODS: Ten patients with a diagnosis of ulcerative colitis were evaluated. Mucus was collected during colonoscopy from all segments of the colon and terminal ileum before surgery, and from the ileal pouch two and eight months after ileostomy closure. The prevalence and mean concentration of the mucosa-associated microflora were compared over time and with historic controls. RESULTS: Veillonella sp was the most prevalent bacterium in patients and controls. Klebsiella sp was significantly more prevalent in the ileum of controls, was not found in patients with ulcerative colitis, and after proctocolectomy returned to values found in controls. Some bacteria such as Enterobacter sp, Staphylococcus sp (coag-), Bacteroides sp (npg), Lactobacillus sp, and Veillonella sp had higher mean concentrations in the ileal pouch of patients after surgery than in controls. CONCLUSION: No bacterium was identified that could be exclusively responsible for the maintenance of the inflammatory process. The mucosa-associated microflora of patients with ulcerative colitis underwent significant changes after proctocolectomy with ileal pouch construction and returned to almost normal values for some bacteria.

Narrowed lumen of the right coronary artery in chronic chagasic patients is associated with ischemic lesions of segmental thinnings of ventricles

Thinning of myocardial segments, mainly at the apex and basal posterior region of left ventricle, are frequent lesions in chronic chagasic cardiopathy (CCC), but still without a well determined etiology. Previously we found severe myocardial microvascular dilatation that could cause ischemia in watershed regions. In this study we analyzed whether narrowness in epicardial coronary arteries in CCC might explain these thinned ventricular lesions. Two groups of dilated hearts with similar weights were compared: eleven hearts from patients with CCC versus four hearts from patients with dilated cardiomyopathy (IDCM). As normal controls we studied three non dilated normal weight hearts. There were no atherosclerotic plaques in the main branches of epicardial coronary arteries and cross-sectional luminal areas of proximal and distal segments were histologically measured. It was found that CCC hearts presented a lower mean luminal area in the right coronary artery (RCA) branch than IDCM, in proximal (4.3 +/- 1.4 vs 6.6 +/- 2.0 mm(2); p = 0.02) and in distal (1.6 +/- 1.0 vs 3.4 +/- 0.9 mm(2); p = 0.01) segments, with no statistical differences with normal hearts (2.7 +/- 1.3 and 1.5 +/- 0.3 mm(2)) in proximal (p = 0.2) and distal (p = 0.11) sections. In conclusion thinning of ventricular wall in CCC patients seems to be ischemic lesions in the peripheral territory irrigated by the right coronary artery, possibly due to a steal phenomenon by the left coronary, induced by micro vessels dilatation.

Vascularized Bone Grafts for Upper Limb Reconstruction: Defects at the Distal Radius, Wrist, and Hand

Vascularized bone grafts have been successfully applied for the reconstruction of bone defects at the forearm, distal radius, carpus, and hand. Vascularized bone grafts are most commonly used in revision cases in which other approaches have failed. Vascularized bone grafts can be obtained from a variety of donor sites, including the fibula, the iliac crest, the distal radius (corticocancellous segments and vascularized periosteum), the metacarpals and metatarsals, and the medial femoral condyle (corticoperiosteal flaps). Their vascularity is preserved as either pedicled autografts or free flaps to carry the optimum biological potential to enhance union. The grafts can also be transferred as composite tissue flaps to reconstruct compound tissue defects. Selection of the most appropriate donor flap site is multifactorial. Considerations include size matching between donor and defect, the structural characteristics of the graft, the mechanical demands of the defect, proximity to the donor area, the need for an anastomosis, the duration of the procedure, and the donor site morbidity. This article focuses on defects of the distal radius, the wrist, and the hand. (J Hand Surg 2010;35A:1710-1718. (C) 2010 Published by Elsevier Inc. on behalf of the American Society for Surgery of the Hand.)

Evaluation of subclinical atherosclerosis by computed tomography coronary angiography and its association with risk factors in familial hypercholesterolemia

Background: Increasing age and cholesterol levels, male gender, and family history of early coronary heart disease (CHD) are associated with early onset of CHD in familial hypercholesterolemia (FH). Objective: Assess subclinical atherosclerosis by computed tomography coronary angiography (CTCA) and its association with clinical and laboratorial parameters in asymptomatic FH subjects. Methods: 102 FH subjects (36% male, 45 +/- 13 years, LDL-c 280 +/- 54 mg/dL) and 35 controls (40% male, 46 +/- 12 years, LDL-c 103 +/- 18 mg/dL) were submitted to CTCA. Plaques were divided into calcified, mixed and non-calcified; luminal stenosis was characterized as >50% obstruction. Results: FH had a greater atherosclerotic burden represented by higher number of patients with: plaques (48% vs. 14%, p = 0.0005), stenosis (19% vs. 3%, p = 0.015), segments with plaques (2.05 +/- 2.85 vs. 0.43 +/- 1.33, p = 0.0016) and calcium scores (55 perpendicular to 129 vs. 38 perpendicular to 140, p = 0.0028). After multivariate analysis, determinants of plaque presence were increasing age (OR = 2.06, for age change of 10 years, CI95%: 1.38-3.07, p < 0.001) and total cholesterol (OR = 1.86, for cholesterol change by 1 standard deviation, CI95%: 1.09-3.15, p = 0.027). Coronary calcium score was associated with the presence of stenosis (OR = 1.54; CI95%: 1.27-1.86, p < 0.001, for doubling the calcium score). Male gender was directly associated with the presence of non-calcified plaques (OR: 15.45, CI95% 1.72-138.23, p = 0.014) and inversely with calcified plaques (OR = 0.21, CI95%: 0.05-0.84, p = 0.027). Family history of early CHD was associated with the presence of mixed plaques (OR = 4.90, CI95%: 1.32-18.21, p = 0.018). Conclusions: Patients with FH had an increased burden of coronary atherosclerosis by CTCA. The burden of atherosclerosis and individual plaque subtypes differed with the presence of other associated risk factors, with age and cholesterol being most important. A coronary calcium score of zero ruled out obstructive disease in this higher risk population. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Bariatric Surgery in Adolescents: Preliminary 1-year Results with a Novel Technique (Santoro III)

Background Bariatric surgery (BS) was recognized as the only treatment for morbid obesity in adolescents. Classic surgical procedures are based on mechanical restriction and/or malabsorption, resulting in a large number of possible complications and demanding lifelong medical attention. A novel BS design, the Santoro III procedure, relies on modifying secretion of the satiogenic hormones GLP-1 and PYY. This approach avoids common BS complications such as prostheses, narrow anastomoses, excluded segments, and malabsorption. This study describes the 1-year follow-up of the first ten adolescents operated on using the Santoro III technique in a pediatric surgical service. Methods Ten adolescents, mean age 16.1 +/- 1.7 years with body mass index (BMI) greater than 40 kg/m(2) (range 44 to 72 kg/m(2)), refractory to at least 2 years of medical weight loss treatment were selected by a multidisciplinary team to undergo BS. This operation consists of a sleeve gastrectomy with enteroomentectomy and partial gastro-ileal derivation. Results After 1 year, mean body weight decreased from 140.3 to 88.6 kg, and BMI decreased from 52.8 +/- 9.5 kg/m(2) to 33.4 +/- 7.7 kg/m(2), with percent of excess BMI lost as 83.9 +/- 17.1%. Glucose, insulin, total cholesterol, LDL-cholesterol, and triglyceride levels decreased significantly, while HDL-cholesterol, hemoglobin, and albumin levels remained unchanged. There were no mortalities or reoperations. The two complications that presented during the trial (intraperitoneal abscess and polyneuritis) resolved with medical treatment without sequelae. All the patients returned to their normal activities and their BMI began to stabilize approximately 2 years following surgery. Conclusions The Santoro III procedure is an attractive option for adolescent BS, with promising 1-year follow-up results. These initial studies should be monitored for long-term outcomes and confirmed on a larger group of patients.