Normal Mastoid Air Cell System Geometry: Has Surface Area Been Overestimated?

Objectives The aim of this study was to emphasize the necessity of a standard in segmentation threshold and algorithm for measuring volume and surface area of mastoid air cell system (MACS).Methods First, we obtained axial computed tomography scans of 54 normal temporal bones from 27 subjects. Then, we manipulated Hounsfield units (HU) image data in DICOM (digital imaging and communications in medicine) files directly using our program. The volume and surface area of MACS were computed and compared at segmentation thresholds (HU) from –700 to 0 at intervals of 50 using 2 algorithms; square pixel based (SP) algorithm and marching square (MS) algorithm.Results No significant difference was found between the volumes computed by SP and MS algorithms at each segmentation threshold. The surface area computed by SP algorithm, however, was significantly larger than that by MS algorithm. We could minimize this significant difference through a modification of the SP algorithm. As the lower HU threshold value was set, the smaller volume was measured. The surface area showed a plateau at a threshold of approximately –200 HU. The segmentation threshold had greater influence on the measured volume of MACS than the algorithm did.Conclusion A standard method for measuring volume and surface area of MACS is thought to be necessary. We suggest that the MS algorithm and –200 HU of the threshold could be a standard in the measurement of volume and surface area of MACS.     

Differences in Chlamydia trachomatis cryptic plasmid loads in two types of female commercial sex workers in Korea

Female sex workers in Korea can generally be divided into one of two categories, namely, historically rooted brothel-based prostitutes (BBPs) and a newly developed category of freelance prostitutes (FLPs). Though some social differences are known, there have been few reports of distinguishing biological characteristics between the two groups. We examined the chlamydial plasmid loads (CPLs) and the numbers of detached host cells (NDCs) from these two groups with different approaches to selling sex. Chlamydial plasmid and human genomic DNA were extracted from endocervical swabs of the subjects, and we determined the CPLs and the NDCs using real-time PCR analysis. Forty-six women in the FLP group and 21 women in the BBP group had a chlamydial infection. The CPL and NDC values were higher in the FLP than in the BBP group (P=0.000, P=0.0001 respectively). In the FLP group, younger-aged women had higher CPLs and more detached cells than did older women (P=0.02, P=0.01 respectively). However, the BBP group did not show any such age-related differences in CPL and NDC values. There was a statistically significant positive correlation between the NDC and the CPL values in the BBPs (P<0.001) as well as in the FLPs (P<0.001). In conclusion, different biological characteristics were observed between FLPs and BBPs, as based on different CPL and the NDC values. The high plasmid loads among the sex workers were isolated from large numbers of scraped cells within a cotton swab. Thus, minor injury may render the endocervical epithel of FLPs more easily detachable than that of BBPs.     

Osteoclast activation in inflammatory periodontal diseases

OBJECTIVE: In this paper, we review the mechanisms thought to be involved in the activation of osteoclasts in periodontitis.
SUMMARY Osteoclasts are regulated by both microbial and host factors. Some factors act directly on cells of the osteoclast lineage, whereas others act indirectly through other cell types in the bone environment. The pro-inflammatory cytokines (interleukins I and 6, tumor necrosis factors) have been implicated in the stimulation of osteoclastic resorption. The roles of the immunoregul-atory cytokines (interleukins 2 and 4, interferon γ) are less clear, but decreased levels of these factors may contribute to periodontitis. A number of lipid mediators may be involved in stimulation of bone resorption. These include bacterial lipopolysaccharide and host-derived platelet-activating factor and prostaglandins. More recently, reactive oxygen intermediates and extracellular nucleo-tides, both present at sites of inflammation, have been investigated as possible modulators of osteoclast activity. The potential use of antiresorptive therapies in periodontitis is reviewed.
CONCLUSIONS: A wide range of host and bacterial factors contribute to the loss of alveolar bone in periodontitis. However, much remains to be understood about the complex mechanisms through which these factors regulate osteoclast activity. Further studies at the cellular and molecular level will lead to a better understanding of these processes and perhaps suggest new approaches for periodontal therapy.     

Is erythematous candidiasis associated with advanced HIV disease?

OBJECTIVES: A multicentre collaborative study by the London HIV and Dentistry Group failed to associate the presence of erythematous candidiasis (EC) with advanced HIV disease. Data from a study of the periodontal health of homosexual men attending a genito-urinary medicine clinic presented an opportunity to investigate social and medical factors related to the presence of EC and mucosal disease. SUBJECTS AND METHODS: 312 men with HIV were examined by a single examiner blinded to HIV status; 22.8% had an indicator condition for AIDS; 37.8% had CD4 lymphocyte counts less than 200 cells mm^?3; and 53.8% met the 1993 case definition for AIDS; 59.6% of the men with HIV had oral manifestations of the infection. The most common were: oral hairy leukoplakia, 44.2%; EC, 26.9%; and pseudomembranous candidiasis (PC), 11.5%. RESULTS: Advanced HIV disease was a less powerful predictor of EC than PC. Advanced HIV disease also predicted the presence of hairy leukoplakia and mucosal ulceration. EC was strongly associated with tobacco use. CONCLUSIONS: While methodological differences explain some variation with previous research, these data also suggest that EC and PC may not carry the same prognostic significance and longitudinal studies are required to confirm these findings.     

Salivary and mucosal immune responses to HIV and its co-pathogens

The profound effects that HIV induces in systemic immunity have been well characterised, but the situation with regard to mucosal immune responses is less clear. Oral cavity fluids have been used as a marker of the mucosal immune system. Whole and parotid saliva IgA, IgA1 and IgA2 concentrations have been found to be lower in both HIV infection and AIDS subjects, whereas serum IgA and IgA subclasses are markedly raised, suggesting a dichotomy between systemic and secretory immunity. Salivary antibodies to HIV can be readily detected and secretory IgA antibody can be neutralising to some strains of HIV. HIV vaccines can also induce antibody responses in saliva, but vaccination routes other than parenteral immunisation are needed. Antibody responses to oral microbes have also been studied and it has been shown that IgA, IgA1 and IgA2 subclass antibody titres to Candida albicans and to Streptococcus mut-ans are increased in whole or parotid saliva from HIV patients, but reduced in AIDS patients, suggesting a compensatory response which is overcome with progressive immunodeficiency. The avidity of salivary IgA antibodies to Candida in HIV seems unimpaired, whereas relative avidities of serum antibodies in HIV patients with candidiasis are lowered. Non-specific factors which may inhibit Candida and other opportunist pathogens are also found in saliva. The candidacidal, myelomonocytic protein calprotectin is present in saliva at levels which are biologically active, although levels are lowered in HIV infection. Overall, HIV infection appears to be associated with disregulation of a number of immune factors at the mucosal surface, but the ability of patients with HIV infection to mount specific antibody secretory responses seems to be relatively intact until late in infection.     

The structural determinants of checkpoint activation

Here, we demonstrate that primed, single-stranded DNA (ssDNA) is sufficient for activation of the ATR-dependent checkpoint pathway in Xenopus egg extracts. Using this structure, we define the contribution of the 5'- and 3'-primer ends to Chk1 activation when replication is blocked and ongoing. In addition, we show that although ssDNA is not sufficient for checkpoint activation, the amount of ssDNA adjacent to the primer influences the level of Chk1 phosphorylation. These observations define the minimal DNA requirements for checkpoint activation and suggest that primed ssDNA represents a common checkpoint activating-structure formed following many types of damage.