An Eight-week, Multicentric, Randomized, Interventional, Open-label, Phase 4, Parallel Comparison of the Efficacy and Tolerability of the Fixed Combination of Timolol Maleate 0.5%/Brimonidine Tartrate 0.2% Versus Fixed Combination of Timolol Maleate 0.5%/Dorzolamide 2% in Patients With Elevated Intraocular Pressure

Purpose: To compare the efficacy and tolerability of the fixed combination of timolol maleate 0.5%/brimonidine tartrate 0.2% versus fixed combination of timolol maleate 0.5%/dorzolamide 2% in patients with elevated intraocular pressure (IOP) over 8 weeks. Patients and Methods: This 8-week, multicentric. interventional, randomized, open-label, parallel group study was conducted Lit 4 centers in Brazil and 1 center in Argentina. Patients with open-angle glaucoma or ocular hypertension were randomized to receive bilaterally fixed combination of brimonidine/timolol maleate 0.5% or fixed combination of dorzolamide 2%/timolol 0.5% twice daily at 8:00 AM and 8:00 PM. A modified diurnal tension curve (8:00 AM 10:30 AM, 02:00 PM, and 4:00 PM) followed by the water drinking test (WDT), which estimates IOP peak of diurnal tension curve, were performed in the baseline and week-8 visits. Adverse events data were recorded at each visit. Results: A total of 210 patients were randomized (brimonidine/timolol, n = 111; dorzolamide/timolol, n = 99). Mean baseline IOP was 23.43 +/- 3.22 mm Hg and 23.43 +/- 4.06 mm Hg in the patients treated with brimonidine/timolol and dorzolamide/timolol, respectively (P = 0.993). Mean diurnal IOP reduction after 8 weeks were 7.02 +/- 3.06 mm Hg and 6.91 +/- 3.67 mm Hg. respectively (P = 0.811). The adjusted difference between groups (analysis of covariance) Lit week 8 was not statistically significant (P = 0.847). Mean baseline WDT peak was 27.79 +/- 4.29 mm Hg in the brimonidine/timolol group and 27.68 +/- 5.46 mm Hg in the dorzolamide/timolol group. After 8 weeks of treatment, mean WDT peaks were 20.94 +/- 3.76 mm Hg (P < 0.001) and 20.98 +/- 4.19 (P < 0.001), respectively. The adjusted difference between groups (analysis of covariance) was not statistically significant (P = 0.469). No statistical difference in terms of adverse events was Found between groups. Conclusions: Both fixed combinations were capable of significantly reducing the mean diurnal IOP, mean diurnal peak, and mean WDT peak after 8 weeks of treatment. Also, both fixed combinations are well tolerated with few side effects.

Submucosal Injection of 0.4% Hydroxypropyl Methylcellulose Facilitates Endoscopic Mucosal Resection of Early Gastrointestinal Tumors

Background and Aims: Submucosal injection of a viscoelastic solution prolongs submucosal lift, thus, facilitating endoscopic mucosal resection. Our objective was to assess the safety and clinical effectiveness of 0.4% hydroxypropyl methylcellulose (HPMC) as a submucosal injectant for endoscopic mucosal resection. Patients and Methods: A prospective, open-label, multicenter, phase 2 study was conducted at 2 academic institutions in Brazil. Eligible participants included patients with early gastrointestinal tumors larger than 10 mm. Outcomes evaluated included complete resection rates, volume of HPMC injected, duration of the submucosal cushion as assessed visually, histology of the resected leisons, and complication rates. Results: Over a 12-month period, 36 eligible patients with superficial neoplastic lesions (stomach 14, colon 11, rectum 5, esophagus 3, duodenum 3) were prospectively enrolled in the study. The mean size of the resected specimen was 20.4 mm (10 to 60 mm). The mean volume of 0.4% HPMC injected was 10.7 mL (range 4 to 35 mL). The mean duration of the submucosal fluid cushion was 27 minutes (range 9 to 70 min). Complete resection was successfully completed in 89%. Five patients (14%) developed immediate bleeding requiring endoclip and APC application. Esophageal perforation occurred in 1 patient requiring surgical intervention. There were no local or systemic adverse events related to HPMC use over the follow-up period (mean 2.2 mo). Conclusion: HPMC solution (0.4%) provides an effective submucosal fluid cushion and is safe for endoscopic resection of early gastrointestinal neoplastic lesions.

Ranolazine Exerts Potent Effects on Atrial Electrical Properties and Abbreviates Atrial Fibrillation Duration in the Intact Porcine Heart

Introduction: In vitro studies and ambulatory ECG recordings from the MERLIN TIMI-36 clinical trial suggest that the novel antianginal agent ranolazine may have the potential to suppress atrial arrhythmias. However, there are no reports of effects of ranolazine on atrial electrophysiologic properties in large intact animals. Methods and Results: In 12 closed-chest anesthetized pigs, effects of intravenous ranolazine (similar to 9 mu M plasma concentration) on multisite atrial effective refractory period (ERP), conduction time (CT), and duration and inducibility of atrial fibrillation (AF) initiated by intrapericardial acetylcholine were investigated. Ranolazine increased ERP by a median of 45 ms (interquartile range 29-50 ms; P < 0.05, n = 6) in right and left atria compared to control at pacing cycle length (PCL) of 400 ms. However, ERP increased by only 28 (24-34) ms in right ventricle (P < 0.01, n = 6). Ranolazine increased atrial CT from 89 (71-109) ms to 98 (86-121) ms (P = 0.04, n = 6) at PCL of 400 ms. Ranolazine decreased AF duration from 894 (811-1220) seconds to 621 (549-761) seconds (P = 0.03, n = 6). AF was reinducible in 1 of 6 animals after termination with ranolazine compared with all 6 animals during control period (P = 0.07). Dominant frequency (DF) of AF was reduced by ranolazine in left atrium from 11.7 (10.7-20.5) Hz to 7.6 (2.9-8.8) Hz (P = 0.02, n = 6). Conclusions: Ranolazine, at therapeutic doses, increased atrial ERP to greater extent than ventricular ERP and prolonged atrial CT in a frequency-dependent manner in the porcine heart. AF duration and DF were also reduced by ranolazine. Potential role of ranolazine in AF management merits further investigation. (J Cardiovasc Electrophysiol, Vol. 20, pp. 796-802, July 2009).

The frequency of anti-beta(2)-glycoprotein I antibodies is low and these antibodies are associated with pulmonary hypertension in mixed connective tissue disease

The objective of this study is to evaluate the prevalence of antiphospholipid antibodies, mainly anti-beta(2)-glycoprotein I (anti-beta(2)-GPI), and their possible clinical and laboratory relevance in mixed connective tissue disease (MCTD). This study included 39 consecutive patients with MCTD (Kasukawa`s criteria) from January, 2005, to March, 2007, and compared them with 21 age- and sex-matched healthy controls. IgG and IgM anticardiolipin (aCL) and anti-beta(2)-GPI were measured by ELISA. Lupus anticoagulant (LA) was detected by functional coagulation tests. Medium to high titres of aCL and anti-beta(2)-GPI antibodies were found in sera from four (10.2%) MCTD patients. One of these patients was found to be positive for IgM aCL, IgM anti-beta(2)-GPI and LA antibodies simultaneously. Additionally, this patient had a previous history of foetal loss in the second trimester and new-onset pulmonary arterial hypertension (PAH). The other three patients had none of the manifestations of antiphospholipid syndrome (APS) or PAH. The mean value of IgG anti-beta(2)-GPI was higher among those MCTD patients with PAH than in the group without PAH (34.2 +/- 46.8 vs 12.3 +/- 9.1, P = 0.018). None of the controls were positive for antiphospholipid antibodies. High to moderate titres of anti-beta(2)-GPI as well as APS were rare in MCTD, and these antibodies may be correlated with the development of PAH in these patients. Lupus (2009) 18, 618-621.

Western blotting method (TESAcruzi) as a supplemental test for confirming the presence of anti-Trypanosoma cruzi antibodies in finger prick blood samples from children aged 0-5 years in Brazil

Some Latin American countries have plans for total control and/or eradication of Chagas disease by the main vector (Triatoma infestans) and by blood transfusion. To achieve this, patients with Chagas disease must be identified. A Western blotting test, TESAcruzi, is described as a supplemental test for diagnosis of Chagas disease using samples collected from children <5 years living in different states of Brazil. Blood samples collected by finger prick on filter paper were sent to the test laboratory by a central laboratory to confirm results obtained previously. Ten percent of negative samples, all doubtful and all positive samples were received. Commercial reagents, IgG indirect immunofluorescence, enzyme immunoassay, and a recently introduced TESAcruzi test were used. From 8788 samples, 163 (1.85%) were reactive by IgG-ELISA and 312 (3.55%) by IgG IIF. From these, 77 (0.87%) were reactive in the TESAcruzi test. The results had high clinical value to identify those truly infected. (C) 2010 Elsevier B.V. All rights reserved.

Quantitative and qualitative comparison of 3.0 T and 1.5 T MR imaging of the liver in patients with diffuse parenchymal liver disease

Purpose: The purpose of our study was to compare signal characteristics and image qualities of MR imaging at 3.0 T and 1.5 T in patients with diffuse parenchymal liver disease. Materials and methods: 25 consecutive patients with diffuse parenchymal liver disease underwent abdominal MR imaging at both 3.0 T and 1.5 T within a 6-month interval. A retrospective study was conducted to obtain quantitative and qualitative data from both 3.0 T and 1.5 T MRI. Quantitative image analysis was performed by measuring the signal-to-noise ratios (SNRs) and the contrast-to-noise ratios (CNRs) by the Students t-test. Qualitative image analysis was assessed by grading each sequence on a 3- and 4-point scale, regarding the presence of artifacts and image quality, respectively. Statistical analysis consisted of the Wilcoxon signed-rank test. Results: the mean SNRs and CNRs of the liver parenchyma and the portal vein were significantly higher at 3.0 T than at 1.5 T on portal and equilibrium phases of volumetric interpolated breath-hold examination (VIBE) images (P < 0.05). The mean SNRs were significantly higher at 3.0 T than at 1.5 T on T1-weighted spoiled gradient echo (SGE) images (P < 0.05). However, there were no significantly differences on T2-weighted short-inversion-time inversion recovery (STIR) images. Overall image qualities of the 1.5 T noncontrast T1- and T2-weighted sequences were significantly better than 3.0 T (P < 0.01). In contrast, overall image quality of the 3.0 T post-gadolinium VIBE sequence was significantly better than 1.5 T (P< 0.01). Conclusions: MR imaging of post-gadolinium VIBE sequence at 3.0 T has quantitative and qualitative advantages of evaluating for diffuse parenchymal liver disease. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

The relationship between prevalent medial meniscal intrasubstance signal changes and incident medial meniscal tears in women over a 1-year period assessed with 3.0 T MRI

Objective Intrasubstance meniscal signal changes not reaching the articular surface on fast spin echo (FSE) sequences are considered to represent mucoid degeneration on MRI. The aim of this study was to evaluate the association of prevalent intrasubstance signal changes with incident tears of the medial meniscus detected on 3.0 T MRI over a 1-year period. Materials and methods A total of 161 women aged a parts per thousand yen40 years participated in a longitudinal 1-year observational study of knee osteoarthritis. MRI (3.0 T) was performed at baseline and 12-month follow-up. The anterior horn, body, and posterior horn of the medial meniscus were scored by two experienced musculoskeletal radiologists using the Boston-Leeds Osteoarthritis Knee Score (BLOKS) system. Four grades were used to describe the meniscal morphology: grade 0 (normal), grade 1 (intrasubstance signal changes not reaching the articular surface), grade 2 (single tears), and grade 3 (complex tears and maceration). Fisher`s exact test and the Cochran-Armitage trend test were performed to evaluate whether baseline intrasubstance signal changes (grade 1) predict incident meniscal tears/maceration (grades 2 and/or 3) in the same subregion of the medial meniscus, when compared to subregions without pathology as the reference group (grade 0). Results Medial meniscal intrasubstance signal changes at baseline did not predict tears at follow-up when evaluating the anterior and posterior horns (left-sided p-values 0.06 and 0.59, respectively). No incident tears were detected in the body. Conclusion We could not demonstrate an association between prevalent medial meniscal intrasubstance signal changes with incident tears over a 1-year period.

3.0-T MRI evaluation of patients with chronic liver diseases: initial observations

Purpose: To describe the use of 3.0-T magnetic resonance imaging (MRI) for the evaluation of chronic liver diseases. Materials and Methods: Two groups of patients who had chronic liver diseases and underwent 3.0-T MRI for evaluation of the liver were included in the study. The first group of patients included 66 consecutive patients (33 male, 33 female; mean age +/- standard deviation, 56 +/- 11). The second group of patients included 30 consecutive patients (18 males, 12 females; mean age +/- standard deviation, 53 +/- 10) in whom Variable-Rate Selective Excitation (VERSE) pulses and improved adjustments procedure were used during the acquisitions. Imaging findings of chronic liver diseases, predetermined artifacts and image quality of all individual sequences in the first group and predetermined artifacts and image quality of T2-weighted sequences in the second group were reviewed retrospectively and independently by two reviewers. chi-Square tests were used to compare the findings between two groups of patients and individual sequences. Kappa statistics were used to determine the extent of agreement between the reviewers. Results: Fifteen dysplastic nodules in 6 of 66 (9%) patients and 12 hepatocellular carcinomas in 11 of 66 (17%) patients were detected. Excluding motion artifacts, three-dimensional (313) T1-weighted gradient-echo (GE) sequence was the least affected sequence by the artifacts. Image quality of T1-weighted 3D-GE sequences was excellent in 43 of 66 (65%) patients. In-phase and out-of-phase T1-weighted spoiled GE (SGE) images were fair in 62 of 66 (94%) and 61 of 66 (92%) patients, respectively. The image quality of short tau inversion recovery (STIR) and half-Fourier rapid acquisition with relaxation enhancement (RARE) sequences were fair in 31 of 66 (47%) and 53 of 66 (80%) patients. STIR and half-Fourier RARE sequences in the second group demonstrated significantly better image quality (P=.03 and P<.0001). Conclusion: 3.0-T MRI allows the acquisition of very high quality postgadolinium 3D-GE sequence, which permitted the detection and characterization of lesions in the setting of chronic liver diseases. The use of VERSE pulses and improved adjustments procedure improved the image quality of T2-weighted sequences. In-phase/out-of-phase SGE sequences are at present of fair quality. (C) 2008 Elsevier Inc. All rights reserved.

Water excitation MPRAGE: An alternative sequence for postcontrast imaging of the abdomen in noncooperative patients at 1.5 Tesla and 3.0 Tesla MRI

Purpose: To evaluate the diagnostic image quality of post-gadolinium water excitation-magnetization-prepared rapid gradient-echo (WE-MPRAGE) sequence in abdominal examinations of noncooperative patients at 1.5 Tesla (T) and 3.0T MRI. Materials and Methods: Eighty-nine consecutive patients (48 males and 41 females; mean age +/- standard deviation, 54.6 +/- 16.6 years) who had MRI examinations including postgadolinium WE-MPRAGE were included in the study. Of 89 patients, 33 underwent noncooperative protocol at 1.5T. 10 under-went noncooperative protocol at 3.0T, and 46 underwent cooperative protocol at 3.0T. Postgadolinium WE-MPRAGE, MPRAGE, and three-dimensional gradient-echo sequences of these three different groups were qualitatively evaluated for image quality, extent of artifacts, lesion conspicuity, and homogeneity of fat-attenuation by two reviewers retrospectively, independently, and blindly. The results were compared using Wilcoxon signed rank and Mann-Whitney U tests. Kappa statistics were used to measure the extent of agreement between the reviewers. Results: The average scores indicated that the images were diagnostic for WE-MPRAGE at 1.5T and 3.0T in noncooperative patients. WE-MPRAGE achieved homogenous fat-attenuation in 31/33 (94%) of noncooperative patients at 1.5T and 10/10 (100%) of noncooperative patients at 3.0T. WE-MPRAGE at 3.0T had better results for image quality, extent of artifacts, lesion conspicuity and homogeneity of fat-attenuation compared with WE-MPRAGE at 1.5T. in noncooperative patients (P = 0.0008, 0.0006, 0.0024, and 0.0042: respectively). Kappa statistics varied between 0.76 and 1.00, representing good to excellent agreement. Conclusion: WE-MPRAGE may be used as a T1-weighted postgadolinium fat-attenuated sequence in noncooperative patients, particularly at 3.0T MRI.

Safety of the etonogestrel-releasing implant during the immediate postpartum period: a pilot study

Background: The effects of etonogestrel (ETG)-releasing contraceptive implant during the immediate postpartum period on maternal safety are unknown. Study design: Forty healthy women exclusively breastfeeding were randomized to receive either ETG-releasing implant 24-48 h after delivery (n=20) or depot medroxyprogesterone acetate (DMPA group; n=20) at the sixth week postpartum. We measured blood pressure, maternal and neonatal weight, body mass index (BMI; kg/m(2)), waist circumference (WC), complete blood count, C-reactive protein, interleukin-6, tumor necrosis factor (TNF-alpha), lipid profile, fasting serum glucose and maintenance of exclusive lactation up to the 12th week postpartum. Results: Decreases in mean maternal weight, BMI (kg/m(2)) and WC were significantly greater in the ETG-releasing implant group than in the MPA group during the first 6 weeks postpartum (-4.64 +/- 2.71 kg vs. -2.6 +/- 2.45 kg mean +/- SD, p=.017; -1.77 +/- 1.06 kg/m(2) vs. -0.97 +/- 0.95 kg/m(2), p=.026; -15.3 +/- 6.72 cm vs. -9.05 +/- 5.84 cm, p=.003, respectively). In addition, total cholesterol and HDL, were lower in DMPA users, and TNF-alpha and leukocytes were higher in DMPA users compared to in the implant group, between 6 and 12 weeks after delivery. The newborns of implant users showed a trend towards gaining more weight, as compared with the infants of the DMPA mothers during the first 6 weeks of life (implant group: +1460.50 +/- 621.34 g vs. DMPA group: +1035.0 +/- 562.43 g, p=.05). The remaining variables, including the duration of exclusive breastfeeding, were similar between the groups. Conclusion: The insertion of ETG-releasing contraceptive implant during the immediate postpartum period was not associated with deleterious maternal clinical effects or with significant maternal metabolic alterations or decreased infant weight gain. (C) 2009 Elsevier Inc. All rights reserved.

Motor development curve from 0 to 12 months in infants born preterm

Aim: To trace a reference curve for motor development from birth up to 12 months of corrected chronological age in infants born preterm and low birth weight. Methods: This is a cross-sectional study with a sample of 308 preterm infants (53% boys) weighing < 2500 g at birth. The Alberta Infant Motor Scale (AIMS) was used for motor development assessment. Results: Comparing the motor performance of preterm infants with infants from a standardized sample on the AIMS, it was found that, except for the age group of the newborn, preterm infants showed lower motor development scores in comparison with the AIMS normative sample in all age groups between 1 and 12 months. The curve of motor development showed a continuous increase in the number of motor skills of preterm infants during their first 12 months of age. However, the average of motor acquisitions of preterm infants showed a nonlinear pattern with a standard indicator of stabilization between 8 and 10 months of age. Conclusion: Preterm infants, 1-12 months of age, showed motor development AIMS scores lower than the standards established in the normative sample. The findings may contribute as norm-reference for assessing the motor development of preterm infants in follow-up programmes in developing countries.

Exercise reduces inflammation and cell proliferation in rat colon carcinogenesis

Purposes: There is evidence that the risk of colon cancer is reduced by appropriate levels of physical exercise. Nevertheless, the mechanisms involved in this protective effect of exercise remain largely unknown. Inflammation is emerging as a unifying link between a range of environment exposures and neoplastic risk. The carcinogen dimethyl-hydrazine (DMH) induces an increase in epithelial cell proliferation and in the expression of the inflammation-related enzyme cyclooxigenase-2 (COX-2) in the colon of rats. Our aim was to verify whether these events could be attenuated by exercise. Methods: Four groups of eight Wistar rats were used in the experiment. The groups G1 and G3 were sedentary (controls), and the groups G2 and G4 were submitted to 8 wk of swimming training, 5 d wk(-1). The groups G3 and G4 were given subcutaneous injections of DMH immediately after the exercise protocols. Fifteen days after the neoplasic induction, the rats were sacrificed and the colon was processed for histological examination and immunohistochemistry staining of proliferating cell nuclear antigen (PCNA) and COX-2. Results: We found a significant increase in the PCNA-labeling index in both DMH-treated groups of rats. However, this increase was significantly attenuated in the training group G4 (P < 0.01). Similar results were observed in relation to the COX-2 expression. Conclusions: From our findings, we conclude that exercise training exerts remarkable antiproliferative and antiinflammatory effects in the rat colonic mucosa, suggesting that this may be an important mechanism to explain how exercise protects against colonic cancer.

Effect of Oral Hygiene with 0.12% Chlorhexidine Gluconate on the Incidence of Nosocomial Pneumonia in Children Undergoing Cardiac Surgery

OBJECTIVE. To evaluate the effect of oral hygiene with 0.12% chlorhexidine gluconate on the incidence of nosocomial pneumonia and ventilator-associated pneumonia (VAP) in children undergoing cardiac surgery. DESIGN. Prospective, randomized, double-blind, placebo-controlled trial. SETTING. Pediatric intensive care unit (PICU) at a tertiary care hospital. patients. One hundred sixty children undergoing surgery for congenital heart disease, randomized into 2 groups: chlorhexidine (n = 87) and control (n = 73). INTERVENTIONS. Oral hygiene with 0.12% chlorhexidine gluconate or placebo preoperatively and twice a day postoperatively until PICU discharge or death. RESULTS. Patients in experimental and control groups had similar ages (median, 12.2 vs 10.8 months; P =. 72) and risk adjustment for congenital heart surgery 1 score distribution (66% in category 1 or 2 in both groups; P =. 17). The incidence of nosocomial pneumonia was 29.8% versus 24.6% (Pp. 46) and the incidence of VAP was 18.3% versus 15% (Pp. 57) in the chlorhexidine and the control group, respectively. There was no difference in intubation time (P =. 34), need for reintubation (P =. 37), time interval between hospitalization and nosocomial pneumonia diagnosis (P =. 63), time interval between surgery and nosocomial pneumonia diagnosis (P =. 10), and time on antibiotics (P =. 77) and vasoactive drugs (P =. 16) between groups. Median length of PICU stay (3 vs 4 days; P =. 53), median length of hospital stay (12 vs 11 days; P =. 67), and 28-day mortality (5.7% vs 6.8%; P =. 77) were also similar in the chlorhexidine and the control group. CONCLUSIONS. Oral hygiene with 0.12% chlorhexidine gluconate did not reduce the incidence of nosocomial pneumonia and VAP in children undergoing cardiac surgery.

Bupivacaine 0.25% and methylene blue spread with epidural anesthesia in dog

Objective To evaluate the extent sensory and motor blocks produced by the epidural injection of different volumes of 0.25% bupivacaine (Bu) with methylene blue (MB), in dogs. Study design Prospective experimental trial. Animals Twenty healthy adult mongrel dogs, weighing 9.9 +/- 1.9 kg. Methods Dogs were randomly allocated into one of four groups that received 0.2, 0.4, 0.6 or 0.8 mL kg-1 of an epidural solution containing 0.25% Bu and MB. Sensory block was evaluated against time by pinching the tail, hind limb interdigital web, toenail bases and the skin over the vertebral dermatomes. Motor block was assessed by ataxia, hind limb weight-bearing ability and by loss of muscle tone of the tail and pelvic limbs. Data were collected at 2, 5, 10, 15 and 30 minutes after the end of epidural injection. After the final time point, dogs were euthanatized and laminectomies were conducted to expose the extent of the dural dye staining. Results The volumes 0.2, 0.4, 0.6 and 0.8 mL kg-1 of 0.25% Bu and MB blocked a mean of 5, 14.2, 20.2 and 21 dermatomes, respectively. The extent of the senory block increased up to a volume of 0.6 mL kg-1. Motor block was longer-lasting and more intense than sensory block. Complete dyeing of the spinal cord with MB was achieved in some dogs at 0.4 mL kg-1 and all dogs at 0.6 mL kg-1. Conclusions The volume of anesthetic injected into the epidural space plays an important role in the quality of the epidural anesthesia. At 0.25%, bupivacaine provided an efficient sensory block at 0.6 mL kg-1. Clinical relevance Relatively high volumes (0.6 mL kg-1) of 0.25%, BU and MB were needed to produce an effective sensory and motor block caudal to the umbilicus, but all spinal cord segments were reached by MB at this dose.

Estimation of R(0) from the initial phase of an outbreak of a vector-borne infection

The magnitude of the basic reproduction ratio R(0) of an epidemic can be estimated in several ways, namely, from the final size of the epidemic, from the average age at first infection, or from the initial growth phase of the outbreak. In this paper, we discuss this last method for estimating R(0) for vector-borne infections. Implicit in these models is the assumption that there is an exponential phase of the outbreaks, which implies that in all cases R(0) > 1. We demonstrate that an outbreak is possible, even in cases where R(0) is less than one, provided that the vector-to-human component of R(0) is greater than one and that a certain number of infected vectors are introduced into the affected population. This theory is applied to two real epidemiological dengue situations in the southeastern part of Brazil, one where R(0) is less than one, and other one where R(0) is greater than one. In both cases, the model mirrors the real situations with reasonable accuracy.