Biomedical subjects
Richard L Gregory
Publications and source records attributed to Richard L Gregory.
Measurements of HIV viral loads from different levels of the respiratory tract.
BACKGROUND: The lung is a common site of disease in HIV infection. Virus has been detected in BAL fluid (BALF) and saliva. However, the relationship between viral loads detected at different levels of the respiratory tract is unknown. METHOD: We measured simultaneous HIV viral loads in parotid saliva (PS), bronchial fluid (BF), BALF, and plasma by reverse transcription polymerase chain reaction in 20 HIV-infected individuals. RESULTS: HIV was detected in 53% of BALF samples, 15% of BF samples, 5% of PS samples, and 88% of plasma samples. Viral loads in plasma and BALF samples were positively correlated. There were significantly higher levels of HIV viral load in both plasma and BALF in subjects with CD4 counts of < 200 cells/ microL compared to those with higher counts. Antiretroviral therapy (ART) was associated with lower BALF and plasma viral loads, and the effect in BALF was independent of the plasma viral load. Interestingly, smoking also was associated with lower levels of both BAL and BF viral loads, independent of the plasma viral load. CONCLUSION: These data demonstrate that while HIV can be detected in the respiratory tract, the viral load is influenced by both local factors (ie, level of the respiratory tree and cigarette smoking) and systemic factors (ie, ART and peripheral CD4 count).
Electrochemical study on microbiology-related corrosion of metallic dental materials.
Microbiology-related corrosion has been noted in industry for many years. It is widely recognized that microorganisms affect the corrosion of metal and alloys immersed in aqueous environments. Under similar conditions, the effect of bacteria in the oral environment on the corrosion of dental metallic materials remains unknown. The purpose of this study is to investigate the corrosion behavior of dental metallic materials in the presence of Streptococcus mutans and its growth byproducts. Samples were commercially pure titanium (CPT), Ti-6Al-4V (TAV), Ti-Ni (TN), Co-Cr-Mo alloy (CCM), 316L stainless steel (SSL), 17Cr-4Ni PH-type stainless steel (PH), and Ni-Cr alloy (NC). Using Gamry corrosion test system, surfaces were exposed to (1) sterilized Ringer's solution as a control for (2), (2) S. mutans mixed with sterilized Ringer's solution; (3) sterilized tryptic soy broth as a control for (4), and (4) byproducts of S. mutans mixed with sterilized tryptic soy broth. Corrosion parameters (EOCP, ECORR, ICORR, etc.) were corrected for all tested samples. Averaged values of these parameters were statistically analyzed by t-test to identify significant differences. It was concluded that (1) S. mutans reduced the EOCP of CPT, TAV, TN, and SSL, and the byproducts of S. mutans reduced the EOCP of TAV, TN, SSL, and PH. (2) S. mutans increased the ICORR of PH, and byproducts of S. mutans increased the ICORR of all the samples. (3) S. mutans reduced the ECORR of CPT, TAV and TN, and the byproducts of S. mutans reduced the ECORR of TN, SSL, PH, and NC. (4) S. mutans increased the IPASS of CPT, and the byproducts of S. mutans increased the IPASS of CPT, PH, and NC.
Distribution of cariogenic bacteria in carious lesions around tooth-colored restorations.
PURPOSE: To compare the distribution of the three most suspected cariogenic groups of bacteria, mutans streptococci, Actinomyces naeslundii genospecies 2, and lactobacilli in carious lesions around tooth-colored restorations. MATERIALS AND METHODS: Samples from extracted teeth with clinical secondary caries around tooth-colored restorations were immuno-labeled with antibodies to the referred groups of bacteria and subsequently analyzed three dimensionally using confocal microscopy. RESULTS: The three different bacterial groups were usually present in secondary caries around tooth-colored restorations suggesting that they are involved in its formation and development.
Shifts of edges and deformations of patterns.
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