Evaluation of the diagnostic value of the tourniquet test in predicting severe dengue cases in a population from Belo Horizonte, State of Minas Gerais, Brazil

Introduction Dengue is prevalent in many tropical and sub-tropical regions. The clinical diagnosis of dengue is still complex, and not much data are available. This work aimed at assessing the diagnostic accuracy of the tourniquet test in patients with suspected dengue infection and its positivity in different classifications of this disease as reported to the Information System for Notifiable Disease in Belo Horizonte, State of Minas Gerais, Brazil between 2001 and 2006. Methods Cross-section analysis of the diagnostic accuracy of the tourniquet test for dengue, using IgM-anti-DENV ELISA as a gold standard. Results We selected 9,836 suspected cases, of which 41.1% were confirmed to be dengue. Classic dengue was present in 95.8%, dengue with complications in 2.5% and dengue hemorrhagic fever in 1.7%. The tourniquet test was positive in 16.9% of classic dengue cases, 61.7% of dengue cases with complications and 82.9% of cases of dengue hemorrhagic fever. The sensitivity and specificity of the tourniquet test were 19.1% and 86.4%, respectively. Conclusions A positive tourniquet test can be a valuable tool to support diagnosis of dengue where laboratory tests are not available. However, the absence of a positive test should not be read as the absence of infection. In addition, the tourniquet test was demonstrated to be an indicator of dengue severity.

Evaluation of the reference value for the Montenegro skin test

Abstract:INTRODUCTION:The Montenegro skin test (MST) has good clinical applicability and low cost for the diagnosis of American tegumentary leishmaniasis (ATL). However, no studies have validated the reference value (5mm) typically used to discriminate positive and negative results. We investigated MST results and evaluated its performance using different cut-off points.METHODS:The results of laboratory tests for 4,256 patients with suspected ATL were analyzed, and 1,182 individuals were found to fulfill the established criteria. Two groups were formed. The positive cutaneous leishmaniasis (PCL) group included patients with skin lesions and positive direct search for parasites (DS) results. The negative cutaneous leishmaniasis (NCL) group included patients with skin lesions with evolution up to 2 months, negative DS results, and negative indirect immunofluorescence assay results who were residents of urban areas that were reported to be probable sites of infection at domiciles and peridomiciles.RESULTS:The PCL and NCL groups included 769 and 413 individuals, respectively. The mean ± standard deviation MST in the PCL group was 12.62 ± 5.91mm [95% confidence interval (CI): 12.20-13.04], and that in the NCL group was 1.43 ± 2.17mm (95% CI: 1.23-1.63). Receiver-operating characteristic curve analysis indicated 97.4% sensitivity and 93.9% specificity for a cut-off of 5mm and 95.8% sensitivity and 97.1% specificity for a cut-off of 6mm.CONCLUSIONS:Either 5mm or 6mm could be used as the cut-off value for diagnosing ATL, as both values had high sensitivity and specificity.

Validation study of an automated wrist monitor, omron model HEM-608, compared with the standard methods for blood pressure measurement

OBJECTIVE - The aim of our study was to assess the profile of a wrist monitor, the Omron Model HEM-608, compared with the indirect method for blood pressure measurement. METHODS - Our study population consisted of 100 subjects, 29 being normotensive and 71 being hypertensive. Participants had their blood pressure checked 8 times with alternate techniques, 4 by the indirect method and 4 with the Omron wrist monitor. The validation criteria used to test this device were based on the internationally recognized protocols. RESULTS - Our data showed that the Omron HEM-608 reached a classification B for systolic and A for diastolic blood pressure, according to the one protocol. The mean differences between blood pressure values obtained with each of the methods were -2.3 +7.9mmHg for systolic and 0.97+5.5mmHg for diastolic blood pressure. Therefore, we considered this type of device approved according to the criteria selected. CONCLUSION - Our study leads us to conclude that this wrist monitor is not only easy to use, but also produces results very similar to those obtained by the standard indirect method.

New Exercise-Dipyridamole Combined Test for Nuclear Cardiology in Insufficient Effort: Appropriate Diagnostic Sensitivity Keeping Exercise Prognosis

AbstractBackground:Myocardial perfusion scintigraphy (MPS) in patients not reaching 85% of the maximum predicted heart rate (MPHR) has reduced sensitivity.Objectives:In an attempt to maintain diagnostic sensitivity without losing functional exercise data, a new exercise and dipyridamole combined protocol (EDCP) was developed. Our aim was to evaluate the feasibility and safety of this protocol and to compare its diagnostic sensitivity against standard exercise and dipyridamole protocols.Methods:In patients not reaching a sufficient exercise (SE) test and with no contraindications, 0.56 mg/kg of dipyridamole were IV administered over 1 minute simultaneously with exercise, followed by 99mTc-MIBI injection.Results:Of 155 patients, 41 had MPS with EDCP, 47 had a SE test (≥ 85% MPHR) and 67 underwent the dipyridamole alone test (DIP). They all underwent coronary angiography within 3 months. The three stress methods for diagnosis of coronary lesions had their sensitivity compared. For stenosis ≥ 70%, EDCP yielded 97% sensitivity, SE 90% and DIP 95% (p = 0.43). For lesions ≥ 50%, the sensitivities were 94%, 88% and 95%, respectively (p = 0.35). Side effects of EDCP were present in only 12% of the patients, significantly less than with DIP (p < 0.001).Conclusions:The proposed combined protocol is a valid and safe method that yields adequate diagnostic sensitivity, keeping exercise prognostic information in patients unable to reach target heart rate, with fewer side effects than the DIP.

Diagnostic performance characteristics of rapid dipstick test for Plasmodium vivax malaria

We compared the diagnostic performance characteristics of newly developed method, the rapid dipstick test, which provides colorimetric determination by developing antibody to the lactate dehydrogenase enzyme of parasites, with conventional standard thick-blood film examination. For the rapid test, OptiMAL commercial kits were used. The results were also evaluated with clinical findings from patients. The parasites were determined by microscopic examination of thick-blood films from 81 patients with vivax malaria from southeastern Anatolia, Turkey. The OptiMAL test results were found to be negative in five patients who were diagnosed clinically and through thick-film testing as having vivax malaria. There was no false positivity observed with the OptiMAL test. We concluded that this rapid malaria test has a lower level of sensitivity than the classical thick-blood-film test for malaria, but that these methods have equal specificity.

Direct Sensitivity Test of the MB/BacT System

In order to evaluate the direct-method test of sensitivity to drugs used in the principal tuberculosis treatment regimes, in the Organon Teknika MB/BacT system, we tested 50 sputum samples positive to microscopy taken from patients with pulmonary tuberculosis and with clinical indications for an antibiogram, admitted sequentially for examination during the routine of the reference laboratory. The material was treated v/v with 23% trisodium phosphate solution, incubated for 24 h at 35°C, and neutralized v/v with 20% monosodium phosphate solution. The material was then centrifuged and the sediment inoculated into flasks containing Rifampin - 2 µg/ml, Isoniazid - 0.2 µg/ml, Pyrazinamide - 100 µg/ml, Ethambutol - 2.5 µg/ml, Ethionamide - 1.25 µg/ml, and Streptomycin - 2 µg/ml. The tests were evaluated using the indirect method in the BACTEC 460 TB (Becton Dickinson) system as the gold standard. The results showed that the Rifampin test performed best, i.e., 100% sensitivity at 95% Confidence Interval (82.2-100) and 100% specificity at 95% Confidence Interval (84.5-100), followed by Isoniazid and Pyrazinamide. In this experiment, 92% of the materials showed a final reading in 30 days; this period represents the time for primary isolation as well as the results of the sensitivity profile, and is within Centers for Disease Control and Prevention recommendations regarding time for performance of the antibiogram. The inoculated flasks showed no contamination during the experiment. The MB/BacT is shown to be a reliable, rapid, fully automated nonradiometric system for the tuberculosis antibiogram.

A comparative study of the TF-Test®, Kato-Katz, Hoffman-Pons-Janer, Willis and Baermann-Moraes coprologic methods for the detection of human parasitosis

This study compares the diagnostic accuracy of the TF-Test® (TFT) for human parasitosis with results obtained using the traditional Kato-Katz (KK), Hoffman-Pons-Janer (HPJ), Willis and Baermann-Moraes (BM) techniques. Overall, four stool samples were taken from each individual; three alternate-day TFT stool samples and another sample that was collected in a universal container. Stool samples were taken from 331 inhabitants of the community of Quilombola Santa Cruz. The gold standard (GS) for protozoa detection was defined as the combined results for TFT, HPJ and Willis coproscopic techniques; for helminth detection, GS was defined as the combined results for all five coproscopic techniques (TFT, KK, HPJ, Willis and BM). The positivity rate of each method was compared using the McNemar test. While the TFT exhibited similar positivity rates to the GS for Entamoeba histolytica/dispar (82.4%) and Giardia duodenalis (90%), HPJ and Willis techniques exhibited significantly lower positivity rates for these protozoa. All tests exhibited significantly lower positivity rates compared with GS for the diagnosis of helminths. The KK technique had the highest positivity rate for diagnosing Schistosoma mansoni (74.6%), while the TFT had the highest positivity rates for Ascaris lumbricoides (58.1%) and hookworm (75%); HPJ technique had the highest positivity rate for Strongyloides stercoralis (50%). Although a combination of tests is the most accurate method for the diagnosis of enteral parasites, the TFT reliably estimates the prevalence of protozoa and selected helminths, such as A. lumbricoides and hookworm. Further studies are needed to evaluate the detection accuracy of the TFT in samples with varying numbers of parasites.

An evaluation of the dot-ELISA procedure as a diagnostic test in an area with a high prevalence of human Toxocara canis infection

The aim of this work was to evaluate a dot-enzyme-linked immunosorbent assay (dot-ELISA) using excretory-secretory antigens from the larval stages of Toxocara canis for the diagnosis of toxocariasis. A secondary aim was to establish the optimal conditions for its use in an area with a high prevalence of human T. canis infection. The dot-ELISA test was standardised using different concentrations of the antigen fixed on nitrocellulose paper strips and increasing dilutions of the serum and conjugate. Both the dot-ELISA and standard ELISA methods were tested in parallel with the same batch of sera from controls and from individuals living in the problem area. The best results were obtained with 1.33 µg/mL of antigen, dilutions of 1/80 for the samples and controls and a dilution of 1/5,000 for the anti-human IgG-peroxidase conjugate. All steps of the procedure were performed at room temperature. The coincidence between ELISA and dot-ELISA was 85% and the kappa index was 0.72. The dot-ELISA test described here is rapid, easy to perform and does not require expensive equipment. Thus, this test is suitable for the serological diagnosis of human T. canis infection in field surveys and in the primary health care centres of endemic regions.

Fast test for assessing the susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin by real-time PCR

Mycobacterium tuberculosis is the bacterium that causes tuberculosis (TB), a leading cause of death from infectious disease worldwide. Rapid diagnosis of resistant strains is important for the control of TB. Real-time polymerase chain reaction (RT-PCR) assays may detect all of the mutations that occur in the M. tuberculosis 81-bp core region of the rpoB gene, which is responsible for resistance to rifampin (RIF) and codon 315 of the katG gene and the inhA ribosomal binding site, which are responsible for isoniazid (INH). The goal of this study was to assess the performance of RT-PCR compared to traditional culture-based methods for determining the drug susceptibility of M. tuberculosis. BACTEC TM MGIT TM 960 was used as the gold standard method for phenotypic drug susceptibility testing. Susceptibilities to INH and RIF were also determined by genotyping of katG, inhA and rpoB genes. RT-PCR based on molecular beacons probes was used to detect specific point mutations associated with resistance. The sensitivities of RT-PCR in detecting INH resistance using katG and inhA targets individually were 55% and 25%, respectively and 73% when combined. The sensitivity of the RT-PCR assay in detecting RIF resistance was 99%. The median time to complete the RT-PCR assay was three-four hours. The specificities for tests were both 100%. Our results confirm that RT-PCR can detect INH and RIF resistance in less than four hours with high sensitivity.

Portable penetrometer for agricultural soil: sensitivity test to identify critical compaction depth

To express the negative effects of soil compaction, some researchers use critical values for soil mechanical strength that severely impair plant growth. The aim of this study was to identify this critical compaction depth, to test the functionality of a new, portable penetrometer developed from a spring dynamometer, and compare it to an electronic penetrometer traditionally used in compaction studies of agricultural soils. Three soils with distinct texture were conventionally tilled using a disk plow, and cultivated with different plant species. The critical soil resistance defined to establish critical compaction depth was equal to 1.5 MPa. The results of the new equipment were similar to the electronic penetrometer, indicating its viability as a tool for assessing the soil physical conditions for plant growth.

Can Soil Penetration Resistance and Bulk Density Be Determined in a Single Undisturbed Sample?

Soil quality indicators such as penetration resistance (PR) and bulk density (BD) are traditionally determined in a single undisturbed soil sample. The aim of this study was to assess the effect of PR measurements of undisturbed samples on the determination of BD in the same sample of two soils differing in clay contents. To this end, samples were collected from the 0.00-0.10 and 0.10-0.20 m layers of two soils of clayey and very clayey texture. Volumetric rings were used to collect a total of 120 undisturbed soil samples from each soil layer that were divided into two subsets containing 60 units each. One sample set, designated “perforated samples”, was used to determine PR and BD in the same undisturbed sample; the other, named “intact samples”, was used to determine BD only. Bulk density values for perforated and intact samples were compared by analysis of variance, using a completely randomized experimental design. Means were compared by the t-test at 5 %. The BD values for the clayey soil were similar in perforated and intact samples from the two layers. However, BD of the very clayey soil was lower in the perforated than in the intact samples at both depths. Therefore, PR and BD in clayey soils can be accurately determined in the same undisturbed sample whereas in very clayey soils, different samples are required for this purpose.

Flow-batch analyser for preparation of calibration standard mixtures in simultaneous multicomponent spectrometric analysis

The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simultaneous determination of several chemical species. However, when this methodology is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high operational cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu2+, Mn2+ and Zn2+ in polyvitaminic and polymineral pharmaceutical formulations, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the preparation of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples h-1 can be carried out with the proposed flow-batch analyser.

Evaluation of tear production with modified Schirmer tear test-1 during the neonatal period in cats

The study aimed to evaluate tear production by means of modified Schirmer tear tes-1 (mSTT-1) in neonate cats. Likewise, correlation between mSTT-1 and STT-1 was assessed in vitro. Standard SST strips were cut in half and after eye lid opening, tear production of neonates (n=15) was daily measured in both eyes (mSTT-1), until the 7th day, and at day 14, 21, and 28. Animals were daily weighted until 28 days of age. Results were compared statistically (P<0.05). During the first 7 days, the overall mSTT-1 mean was 0.76 wetting/minute. Significant differences between right and left eyes were not observed at any time point (P=1.00). Tear secretion increased significantly, from the 14th to 28th day, in comparison with 7 first days (P<0.05). Positive correlation between maturity parameters and tear secretion was observed (P<0.0001). Distance between slopes of each strip changed significantly (P<0.0001). It was concluded that tear secretion in the neonatal period of cats is very below the reference values described for young and adults of the same species. It is not possible to extrapolate results obtained with mSTT-1 to standard STT-1.

Standardization of a computerized method for calculating autonomic function test responses in healthy subjects and patients with diabetes mellitus

The objectives of the present study were 1) to compare results obtained by the traditional manual method of measuring heart rate (HR) and heart rate response (HRR) to the Valsalva maneuver, standing and deep breathing, with those obtained using a computerized data analysis system attached to a standard electrocardiograph machine; 2) to standardize the responses of healthy subjects to cardiovascular tests, and 3) to evaluate the response to these tests in a group of patients with diabetes mellitus (DM). In all subjects (97 healthy and 143 with DM) we evaluated HRR to deep breathing, HRR to standing, HRR to the Valsalva maneuver, and blood pressure response (BPR) to standing up and to a sustained handgrip. Since there was a strong positive correlation between the results obtained with the computerized method and the traditional method, we conclude that the new method can replace the traditional manual method for evaluating cardiovascular responses with the advantages of speed and objectivity. HRR and BPR of men and women did not differ. A correlation between age and HRR was observed for standing (r = -0.48, P<0.001) and deep breathing (r = -0.41, P<0.002). Abnormal BPR to standing was usually observed only in diabetic patients with definite and severe degrees of autonomic neuropathy.

The C-peptide response to a standard mixed meal in a group of Brazilian type 1 diabetic patients

In order to analyze the different parameters used in the interpretation of C-peptide response in a functional test, we compared a group of 26 type 1 diabetics aged 21.1 ± 8.2 years, with a diabetes duration of 7.9 ± 6.7 months, with a group of 24 non-diabetic subjects aged 25.0 ± 4.4 years. A standard mixed meal of 317 kcal was used as a stimulus. Blood sampling for C-peptide determinations was performed at regular intervals. Although all the studied C-peptide variables were significantly lower in the diabetic group (P<0.0001), some overlapping of parameters was observed between the two groups. The highest degree of overlapping was found for basal value (BV) (30.8%) and percent increase (42.31%), and the lowest for incremental area, absolute increase, peak value (PV) (3.8%), and total area (7.7%) (c2 = 31.6, P<0.0001). We did not observe a definite pattern in the time of maximum response among the 21 diabetics who showed an increase in C-peptide levels after the stimulus. In this group, however, there was a highly significant number of late responses (120 min) (c2 = 5.7, P<0.002). Although BV showed a significant correlation with PV (rS = 0.95, P<0.0001), the basal levels of C-peptide did not differentiate the groups with and without response to the stimulus. We conclude that the diabetic group studied showed delayed and reduced C-peptide responses, and that the functional test can be an important tool for the evaluation of residual ß cell function.