The SAE Vehicle Sound Level Form Committee continues to ensure the SAE road vehicle standards are maintained. Currently, there is a trend to move to internationally recognized standards that are technically valid procedures for rating the various products or subsystems. Although SAE has not initiated a development program, the light-vehicle standards group is actively reviewing an ISO project to develop more representatives of urban driving operations. All proposals are being evaluated to ensure that the procedure accommodates all vehicle designs including the US-style electronic-controlled automatic transmissions. An SAE horn and an accessory component committee are both actively involved in updating or developing new standards. SAE, while not involved in any major new initiatives, provides a significant role in review of world procedures. The expansion of our industrial world boundaries requires a continuing adjustment of our priorities to ensure we maintain standards that are relevant and provide the US-based industry an equal opportunity to be active participants in the global markets.
Exterior noise is the only acoustic attribute regulated for passenger cars and light trucks. The primary procedure used to quantify this noise is an outdoor passby test conducted under full-throttle acceleration. Unless specified noise levels are met under this procedure, a vehicle may not be sold in a given market jurisdiction. Recent reduction of European regulatory limits by 3 dB has re-enforced many of the technical challenges faced in designing and testing vehicles to meet these new requirements. These challenges include: better understanding and control of test and environmental variables, more accurate methods of noise prediction, and improved techniques for isolating and reducing individual source contribution. In recent investigations, sound intensity has been employed to isolate tire/pavement interaction noise for vehicles under passby conditions. This has led to the determination that tires can produce significantly higher noise levels under the torque of acceleration than under cruise conditions. As a result, tires are often the major noise source when the total vehicle noise approaches the new regulatory limits. This paper reviews the variables associated with the passby test procedure, the effects of vehicle acceleration on tire/pavement interaction noise, and the needs for improved predictive methods.
To the Editors: The use of human immunodeficiency virus (HIV) genotyping for identifying the most effective regimens in HIV-infected adults failing highly active antiretroviral therapy led to improved virologic response as compared with regimens selected on the basis of antiretroviral exposure history. In contrast, similar studies conducted in small cohorts of HIV-infected children failed to demonstrate a clear advantage of antiretroviral resistance testing over antiretroviral exposure history. In this study, we have genotyped HIV reverse transcription and protease genes in 17 children (ages 4.5–11.3 years) between 2000 and 2001, at treatment failure and have changed antiretroviral drugs according to HIV genotype profiles. All 17 children who were included showed an elevated viral load (>1000 copies/mL) for at least 9 months during the last year before genotyping and had failed from 1–5 regimens during that time. All the HIV-infected children had received a combination of at least 2 nucleoside reverse transcriptase inhibitors (NRTIs) (17 of 17) and while 8 of 17 had been treated with a PI containing regimen; none of them was previously treated with non-NRTIs (Table 1). Adherence to therapy was based on reports from children and caretakers and on calculation of quantities of drugs that were requested at each visit. At the time of treatment failure, we identified substitutions in both the reverse transcription and the protease genes in samples from 94% of children.TABLE 1: Nucleoside Reverse Transcription Inhibitors Used in HIV TreatmentWild-type sequences could not be identified in any sample from this cohort of HIV-infected children. Drug-specific genotypic resistance, identified on the basis of the IAS mutation list,4 was commonly observed for all the NRTIs as shown in detail in Table 1. Antiretroviral therapy was changed by substitution of at least one antiretroviral medication in all patients, except in patient 17. Since none of the patients had been previously exposed to non-NRTI drugs whereas 8 of 17 had received a drug of the protease inhibitor class, we introduced efavirenz in the therapeutic regimens of 11 children. Virologic and immunologic data were collected at 2- to 3-month intervals for at least 12 months. We observed a significant suppression of viral load (<1000 copies) 3-6 months after treatment change. HIV suppression was detected in 8 of the 17 patients from 6 to 35 months (stably undetectable in 5 cases), whereas in another 5 children viral load remained elevated through 12 months of follow-up. CD4+ percentages showed a significant increase from baseline levels in the same children who showed virologic suppression, except in patient 10 who had already started the treatment with 44% of CD4, suggesting that their treatment regimens were effective to induce immunologic reconstitution. The remaining patients (patients 1, 3, 4 and 13) showed a rapid, but transient, decline of viral load after treatment change. Because of the high risk of false negatives, we have performed an additional HIV genotyping in the remaining 9 patients who showed an unsatisfactory response to medication changes. In patients 1 and 13, we detected additional mutations in reverse transcription gene (Table 1) that conferred resistance to efavirenz, thereby accounting for the inadequate response to the previous change of antiretroviral treatment. HIV genotyping did not reveal any resistance-associated mutation in 7 children who had failed 2 changes of treatment regimens, suggesting that limited adherence may account for this observation. Our study demonstrates that HIV genotyping based treatment choices in 17 infected pretreated children led to persistent viral suppression and immunologic reconstitution in 10 children, suggesting that use of this assay improves clinical outcome of antiretroviral-experienced children. A previous study failed to show benefit of HIV resistance testing in a cohort of 18 children. We believe that the limited availability of novel antiretroviral medications and variable adherence to therapeutic regimens may account the different results that are observed in these studies. Drs Badolato and Schumacher contributed equally to this work. Raffaele Badolato, MD, PhD R. Fabian Schumacher, MD Elisabetta Rodella, MD Franco Gargiulo, MD Carlo Torti, MD Luigi D. Notarangelo, MD Marzia Duse, MD Istituto di Medicina Molecolare "Angelo Nocivelli" Clinica Pediatrica Cattedra di Malattie Infettive Laboratorio di Microbiologia University of Brescia Brescia, Italy
The concept of the protected bronchoalveolar lavage (PBAL) is to improve the diagnostic yield in bacterial pneumonia by unifying the high sensitivity of bronchoalveolar lavage (BAL) and specificity of the protected specimen brush (PSB). HIV-infected patients have been shown to have a high incidence of bacterial pneumonia as well as bacterial colonisation of the tracheobronchial tree. We therefore studied the value of PBAL in this population.During a period of twelve months 40 episodes in 36 patients with symptoms suggestive of pneumonia were investigated retrospectively. In all cases without infiltrates on chest radiograph a CT-scan of the chest was performed. Patients without infiltrates also in CT-scan served as controls. Bronchoscopic investigation included a PSB and a PBAL in the same lung segment most prominently affected. Microbiological workup was performed for bacterial agents, mycobacteria, fungi, viruses and parasites. Quantitative cultures for bacteria were considered significant in case of > or equal to 10(3) cfu/ml in PSB and > or equal to 10(4) cfu/ml in PBAL.32 episodes in 28 patients were identified as pneumonia. A definite diagnosis could be established in 19/32 (59%) of cases. Bacteria accounted for 10/19 (53%). Pneumocystis carinii for 9/19 (47%) of cases including one case that revealed mixed infection with Streptococcus pneumoniae and Pneumocystis carinii. Another pneumonia was due to Aspergillus fumigatus. The sensitivity for bacterial pneumonia was 44% for PSB and 56% for PBAL, the specificity 100%. The overall diagnostic accuracy was 60% and 68%, respectively. The yield for Pneumocystis carinii was 8/9 (89%).PBAL as compared to PSB had a superior diagnostic yield for bacterial pneumonia. As PBAL additionally conserved the yield of BAL reported for Pneumocystis carinii, it may represent a rational diagnostic technique for pneumonia in HIV-infected patients.
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