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Biomedical subjects

Stephen R Porter

Publications and source records attributed to Stephen R Porter.

At least 19 recordsLinked to original sources
PubMed2007

Human herpesvirus 8 genoprevalence in populations at disparate risks of Kaposi's sarcoma.

The prevalence of human herpesvirus 8 (HHV-8) in populations at different risks of developing Kaposi's sarcoma (KS) was assessed using a protocol involving immunomagnetic fractionation of CD45+ blood cells prior to detection of the HHV-8 genome by nested PCR. Preliminary studies using blood of eight gay men infected by human immunodeficiency virus-1 (HIV-1) revealed that, for the detection of HHV-8 DNA derived from open reading frame (ORF) 26 of the HHV-8 genome, this protocol provided substantially higher rates (100%) compared to one involving red blood cell (RBC) lysis (0%) and to another requiring double density gradient centrifugation (DDGC) of leukocytes (13%). When the CD45+ fractionation protocol was applied to samples from 103 other HIV-1-infected patients (the vast majority of whom were gay men) and 100 blood donors, the ORF 26 DNA detection rates obtained were 37% and 8%, respectively. When DNA from the variable region 1 of ORF K1 was additionally amplified from samples of the blood donors, a detection rate of 9% was achieved. This rate was highly concordant with the ORF 26 DNA detection rate. Furthermore, the ORF K1 sequences were predominantly unique, assignable to genotypes A1, A4, and C3. When assays for anti-HHV-8 and anti-herpes simplex viruses (HSV) 1 and 2 were applied, significant concordances between HHV-8 DNA detection rates and those relating to anti-HHV-8 and to anti-HSV 1 and 2 were more frequently observed for HIV-1-infected patients than for blood donors. The higher-than-expected HHV-8 genoprevalence rate in blood donors requires further confirmation in view of its implications for post-transfusion HHV-8 transmission.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Oral manifestations of syphilis.

The past decade has shown a significant rise in the prevalence of infective syphilis in the developed world, and striking increases in its frequency have occurred in Eastern Europe, particularly the UK, and in the US. Although oral manifestations of syphilis are most likely to be observed during secondary disease, all stages of the disease can give rise to oral lesions. Significant oral lesions such as gumma-associated bony destruction and a possible predisposition to oral squamous cell carcinoma are associated with tertiary disease. Since the prevalence of infective syphilis in heterosexuals has been increasing, there has now been a gradual rise in the number of children born with congenital syphilis. Consequently, the congenital disease gives rise to dental anomalies as well as bone, skin, and neurological anomalies of the face. The aim of this report is to review syphilis-related oral lesions, as well as to summarize the relations between human immunodeficiency virus (HIV) and syphilis.

HIV Infections↗
PubMed2005

Composition of in vitro denture plaque biofilms and susceptibility to antifungals.

The aim of this study was to investigate the composition of microcosm denture plaque biofilms and the susceptibility of Candida spp. within these biofilms to antifungal agents. An in vitro model was employed to grow oral biofilms derived from denture associated stomatitis (DAS) patient samples to assess fungal growth in the presence and absence of antifungal agents. The compositions of genera present in vitro were found to be similar to those exhibited on the mucosa and denture fitting surfaces of DAS samples. Exposure to single agents, e.g., miconazole, fluconazole or chlorhexidine did not inhibit growth of Candida spp. when used in clinically relevant doses. Combinations of miconazole and chlorhexidine, pulsed into the system to mimic patient use, did reduce bacterial and candidal growth for several days. Hence, the use of dual-therapy appeared to be useful in reducing the number of viable organisms within denture plaque grown in vitro although resistance to these agents was also evident.

Aged↗
PubMed2005

Cowden's syndrome affecting the mouth, gastrointestinal, and central nervous system: a case report and review of the literature.

Cowden's syndrome (CS) is a rare genodermatosis, of autosomal dominant inheritance and variable phenotype, principally characterized by the formation of hamartomas in various organs, including skin, thyroid, breast, brain, and gastrointestinal tract and by the increased risk for the development of malignancy. The present report details the features of a very rare presentation of Cowden's syndrome affecting not only the mouth and gastrointestinal mucosa but also the central nervous system.

Adult↗
PubMed2004

Salivary production of IgA and IgG to human herpes virus 8 latent and lytic antigens by patients in whom Kaposi's sarcoma has regressed.

IgG and IgA antibodies with specificities to a latent and a lytic antigen of human herpes virus 8 (HHV-8) were detectable in the saliva and serum of eight patients whose Kaposi's sarcoma had regressed, seven of whom were HIV-1 infected. The measurement of antibody-specific activity and secretion rate, and the detection of secretory IgA all indicate anti-HHV-8 antibody activity in saliva. The specific humoral responses possibly influence mucosal replication of HHV-8, and in turn, that of HIV.

Antibodies, Viral↗
PubMed2004

Susceptibility of Candida albicans biofilms grown in a constant depth film fermentor to chlorhexidine, fluconazole and miconazole: a longitudinal study.

OBJECTIVES: The aim of this study was to assess the resistance of Candida albicans biofilms to both antifungal and antimicrobial agents in vitro. METHODS: Biofilms of C. albicans were grown on denture acrylic discs in a constant depth film fermentor and maintained with artificial saliva. The MIC of fluconazole, miconazole and chlorhexidine for C. albicans was first determined. Using these data, 72 h biofilms were exposed to these agents at different MIC levels. In order to assess growth, biofilms were removed from the fermentor, incubated in the test agent for various periods, the biofilms disrupted and the viable yeast cells present determined. The MIC for these cells was then also determined. In a separate experiment, biofilms of various ages (2-72 h) were exposed to sub-biofilm MIC concentrations for two different periods. RESULTS: C. albicans biofilms were found to be highly resistant to fluconazole and miconazole compared with the same cells grown in suspension (>/=1024 x MIC). In contrast, chlorhexidine inhibited the growth of C. albicans biofilms at a concentration up to 8 x MIC. When the susceptibility of biofilms over time was investigated, higher reductions were observed for chlorhexidine and miconazole than fluconazole for biofilms of 2 and 6 h. CONCLUSIONS: We have shown in this study that the susceptibility of C. albicans to antifungal and antimicrobial agents changes throughout biofilm development.

Antifungal Agents↗
PubMed2003

The utility of tolonium chloride rinse in the diagnosis of recurrent or second primary cancers in patients with prior upper aerodigestive tract cancer.

BACKGROUND: The clinical utility of tolonium chloride rinse was compared with unaided visual examination alone in the diagnosis of oral carcinoma in patients previously treated for carcinoma of the upper aerodigestive tract. METHODS: A total of 668 patients were enrolled in this multicenter study. At each site, an oral clinical visual examination was completed by one investigator followed by tolonium chloride rinse and examination by a second investigator blinded to the examination findings of the first investigator. If a lesion was considered suspicious (urgent biopsy required at the first visit), the lesion was biopsied after tolonium chloride rinsing. Patients with lesions characterized at the first visit as not suspicious (biopsy not urgent) or that stained with tolonium chloride were asked to return for a second visit. At the second visit, any residual lesion or lesions that retained tolonium chloride were biopsied. RESULTS: A total of 96 biopsies was performed in 81 of the 668 patients (12.1%), of which 30 (31.3%) were diagnosed histologically as carcinoma/carcinoma in situ (CIS) and the remainder as inflammation (31.3%), keratosis (26.6%), dysplasia (21.9%), ulcer (2.1%), other (3.1%), or no abnormality (1.0%). Of the 30 lesions with the diagnosis of carcinoma/CIS, 12 (sensitivity 40.0%) were considered to be clinically suspicious (CS+), whereas 29 (sensitivity 96.7%) retained tolonium chloride (p =.0002). The predictive values of a positive test for clinical examination and tolonium chloride staining were similar (36.4% vs 32.6%; p =.5871), indicating that the greater sensitivity of tolonium chloride was not associated with an excessive number of unnecessary biopsies (false positives). CONCLUSIONS: Tolonium chloride rinse is more sensitive than clinical examination alone in detecting lesions that might be found on biopsy to be carcinoma or CIS. The increased sensitivity is largely attributed to lesions that stain but were not detected clinically on visual examination.

Aged↗
PubMed2003

Oral pemphigus vulgaris associated with HIV infection.

Vesiculobullous disease in association with HIV infection is extremely rare. This report details the presentation and management of pemphigus vulgaris in an individual with HIV infection. The clinical characteristics and response to therapy appear not to be modified by coexistent HIV infection. However, the management of pemphigus vulgaris relies on immunosuppressive therapy potentially resulting in HIV disease progression. Cyclosporine has in vitro antiretroviral activity and, currently, should be considered as a possible treatment for individuals with pemphigus vulgaris and HIV infection.

Adult↗
PubMed2003

Formation of Candida albicans biofilms on non-shedding oral surfaces.

The aim of this investigation was to determine the ability of Candida albicans to form biofilms on enamel, dentine and denture acrylic of various surface roughnesses. Biofilms of C. albicans were grown on various materials in a constant depth film fermenter (CDFF) and maintained with artificial saliva. Enamel, dentine and denture acrylic were prepared to the same surface roughness using silicon carbide grit. In a separate experiment, denture acrylic was prepared to different surface roughnesses. At various intervals, the materials were removed from the CDFF, the biofilms disrupted and the number of yeast and hyphae present determined. The total number of yeast cells present on enamel was higher than either dentine or acrylic. The highest numbers of yeast cells were found on the roughest surfaces at 6 h; however, higher numbers of hyphae were found on enamel at 6 h and 24 h. Confocal laser scanning microscopy images revealed that the maturation of biofilms on denture acrylic may be dependent upon hyphal cells. The results of the present study show that both the type of surface and their roughness affect the initial formation and subsequent structure of developing of C. albicans biofilms.

Acrylic Resins↗
PubMed2003

Prion disease: possible implications for oral health care.

BACKGROUND: Prion diseases are a group of rare fatal neurodegenerative disorders in humans and animals that are histopathologically characterized by spongiform change within the central nervous system. TYPES OF STUDIES REVIEWED: The author reviewed all available case reports and any studies of the oral aspects of prion diseases published in peer-reviewed journals and available via PubMed. He then outlined the risk of nosocomial transmission of prions in dental health care. RESULTS: Sporadic Creutzfeldt-Jakob disease, or sCJD, is the most common of the acquired human prion disorders, and it typically affects elderly people and leads to rapid death. In contrast, variant CJD, or vCJD, has affected young adults from Europe, giving rise to a slow onset disorder comprising both psychiatric and neurological upset. Oral neurological manifestations are rare and seem to occur only in people with vCJD; there are no oral mucosal or gingival manifestations of prion disease. Prions can be detected in the oral tissues--usually the gingivae and dental pulp--of animals experimentally infected with prions. In contrast, prions have not been detected in the pulpal tissue of people with sCJD, and there are no data of pulpal infection in vCJD. There also are no data suggesting that prions are transmitted easily in the dental setting, but there remains the rare risk of such transmission if appropriate infection control measures are not adhered to. CLINICAL IMPLICATIONS: Few people in the United States and worldwide have prion disease. Oral manifestations are rare. Evidence suggests that the risk of transmission and acquisition of a prion infection as a result of dental treatment is rare, if appropriate infection control measures are maintained.

Adult↗
PubMed2002

Synergism between HIV and other viruses in the mouth.

The HIV family replicate in and are shed from the mouth. Oral sexual practices potentially contribute to the overall extent of HIV transmission, particularly if high-risk practices are not restricted. Herpesviruses and papillomaviruses that appear in the oral cavity can determine oral HIV replication. The mechanisms probably include heterologous transactivation, enhanced expression of HIV receptors and co-receptors in target cells, release of cytokines and chemokines, and production of superantigens. Oral diseases peculiar to, or more common in, the HIV-infected patient further predispose to heightened oral HIV replication and trafficking. Defining the mechanisms by which oral viruses interact with HIV in the co-infected host should permit intervention measures against oral HIV transmission to be more precisely targeted.

Epstein-Barr Virus Infections↗
PubMed2002

Mixed patterns of transmission of human herpesvirus-8 (Kaposi's sarcoma-associated herpesvirus) in Malawian families.

To study transmission patterns of human herpesvirus-8 (HHV-8) (Kaposi's sarcoma-associated herpesvirus) in families in Malawi, nucleotide sequences derived from two hypervariable loci of the HHV-8 genome, the V1 and V2 regions of open reading frame K1 (K1/V1 and K1/V2, respectively), were amplified from blood and mouth rinse samples of 22 patients with treated and untreated Kaposi's sarcoma (KS) and their first-degree relatives (n=67). In patients with KS, vincristine therapy was significantly associated with non-detectability of circulating, but not oral, K1/V1 DNA. Intra-familial K1/V1 phylogenetic comparisons of eight families were possible. Both identical and non-identical sequences were observed between family members, suggesting transmission of HHV-8 along both intra- and extra-familial transmission routes.

Adolescent↗
PubMedDate not supplied

Infectious hepatitis C, hepatitis G, and TT virus: review and implications for dentists.

In the past 10 years, hepatitis C and G viruses have been identified, and in the last two years a further parenterally transmitted agent, termed TT virus (TTV), has been discovered. These viruses have a worldwide distribution and frequently cause chronic infection. The purpose of this article was to promote an understanding of these viral agents and their relevance in dental practice. Infected patients may develop a chronic carrier state without clinical disease or may develop liver disease, and may have related oral conditions. Dental providers will see a growing number of patients with HCV/HGV and possibly TTV infection. All of these patients require appropriate infection control measures during dental treatment.

Blood-Borne Pathogens↗