Sporadic versus syndromic keratocysts-Can we predict treatment outcome? A review of 102 cysts.

OBJECTIVES: Keratocystic odontogenic tumor (KCOT) demonstrates variable growth mechanisms and biologic behavior, partly due to origin and histology. We looked for the most contributing factors in predicting outcome of treatment. SUBJECTS AND METHODS: We retrospectively reviewed 118 medical files of patients diagnosed with KCOT (by tissue biopsy before surgical treatment) with/without nevoid basal cell carcinoma syndrome (NBCCS) from 1995 to 2015. Data were recorded and analyzed statistically to determine the treatment-outcome correlation. KCOTs in NBCCS patients were termed "syndromic" and random KCOTs termed "sporadic." RESULTS: Of 102 cysts, 32 were diagnosed with NBCCS. Sporadic KCOTs were significantly larger upon diagnosis (p < .017). Factors most indicative of postsurgical complications are older age (p < .011), upper jaw location, and size of lesion ≥9.5 cm². Sporadic KCOTs significantly increased the chances of complications approximately threefold (p < .043). Higher recurrence rate was significant in syndromic cysts (47%) compared to sporadic cysts (20%) (p < .009). Recurrence time was 3 years on average. CONCLUSIONS: Postsurgical complications may be expected in: older patients, upper jaw location, extensive lesions, and sporadic KCOT. Most KCOT recurrence is diagnosed 3 years from treatment.

Prevalence of hepatitis B virus markers among hospital personnel in Israel: correlation with some risk factors.

During 1986-1987, 480 employees of the Tel-Aviv Medical Center were screened for hepatitis B virus (HBV) markers as a preliminary step in a vaccination campaign. One hundred and seventeen (24.4%) had evidence of previous infection, including nine (1.9%) carriers. The effect of potential risk factors on seropositivity was evaluated by multiple logistic regression analysis, which enabled assessment of the individual contribution of each risk factor under the specific environmental conditions. The following risk factors were found to influence seropositivity: origin from Third World countries as opposed to the Western World, employment as sanitary workers, age over 40 years, and history of accidental needle punctures. In the heterogeneous Israeli population, hospital workers had a relatively high prevalence of HBV markers, probably resulting from occupational exposure.

Microcosm studies of microbial degradation in a coal tar distillate plume.

Investigation of a groundwater plume containing up to 24 g l(-1) phenolic compounds suggested that over a period of nearly 50 years, little degradation had occurred despite the presence of a microbial community and electron acceptors within the core of the plume. In order to study the effect of contaminant concentration on degradation behaviour, laboratory microcosm experiments were performed under aerobic and anaerobic conditions at four different concentrations obtained by diluting contaminated with uncontaminated groundwater. The microcosms contained groundwater with total phenols at ca. 200, 250, 660 and 5000 mg l(-1), and aquifer sediment that had been acclimatised within the plume for several months. The microcosms were operated for a period of 390-400 days along with sterile controls to ascertain whether degradation was microbially mediated or abiotic. Under aerobic conditions, degradation only occurred at concentrations up to 660 mg l(-1) total phenols. At phenol concentrations below 250 mg l(-1) a benzoquinone intermediate, thought to originate from the degradation of 2,5-dimethylphenol, was isolated and identified. This suggested an unusual degradative pathway for this compound; its aerobic degradation more commonly proceeding via catecholic intermediates. Under anaerobic conditions, degradation only occurred in the most dilute microcosm (total phenols 195 mg l(-1)) with a loss of p-cresol accompanied by a nonstoichiometric decrease in nitrate and sulphate. By inference, iron(III) from the sediment may also have been used as a terminal electron acceptor, in which case the amount of biologically available iron released was calculated as 1.07 mg Fe(III)/g of sediment. The study shows that natural attenuation is likely to be stimulated by dilution of the plume.

Release of contaminants from a heterogeneously fractured low permeability unit underlying a DNAPL source zone.

The invasion of DNAPL into fractured low permeability deposits results in the formation of secondary source zones that represent a long-term source of VOCs to adjacent aquifers. We present data from a site underlain by a fractured mudstone contaminated with TCE DNAPL that was poised for release following remediation of the overlying aquifer. Observations of contaminant distributions and fracture networks from the site and a nearby mudstone exposure respectively, enabled prediction of the imminent aquifer recontamination. The fractures, likely formed by gypsum dissolution, were characterised by fracture apertures and spacings that ranged from 0.01 to 49 mm and 0.047 to 3.37 m (10th and 90th percentile values) respectively. Numerical model results show that prediction of outward mass flux in the first year was highly variable (8 to 32 g/m²/d for an initial constant concentration with depth profile) and dependent on both the fracture spacing and aperture and the contaminant distribution. However after 1 year, assuming a heterogeneous distribution of fractures, mass flux was predictable within a narrow range of values (at 20 years; 0.04-0.08 g/m²/d). Similar results were obtained from more typical fracture networks with spacings of 0.1 to 0.5 m and apertures of 10 to 100 µm. These results suggest that when considering potential recontamination in a bounding aquifer, fracture characterisation may not be necessary and instead the focus should be on determining the surface area contributing contaminant mass to an aquifer, the contaminant concentration depth profiles, the hydraulic properties of the receiving aquifer and the elapsed time since aquifer remediation.

Postdischarge surveillance after cesarean section.

BACKGROUND: Cesarean section is a major surgical procedure with a relatively short hospital stay. A significant rate of surgical site infection after this procedure is missed by standard inpatient surveillance. This study aimed to evaluate a method of postdischarge surveillance and compare results with the incidence of infection before discharge. METHOD: A postdischarge survey was sent on day 30 to 277 women who had delivered by cesarean section during the 12-month study period. A follow-up telephone interview was conducted if the questionnaire had not been returned within 2 weeks, if a diagnosis of infection could not be clearly determined from the participant's responses, or to confirm the diagnosis of infection. If follow-up was not completed, a chart audit was undertaken. RESULTS: A total response rate of 89 percent (247/277) was obtained, and 28 women with a surgical site infection were identified from the survey. Telephone follow-up and chart review of patients with possible infection and of nonresponders identified 32 percent more postdischarge infections (14/42). The overall infection rate was 17 percent compared with 2.8 percent at discharge. CONCLUSIONS: Postdischarge surveillance is necessary to determine accurate surgical site infection rates after cesarean section, increase awareness of caregivers about infection control problems, and indicate the need for appropriate follow-up care. Women undergoing a cesarean delivery should be informed of the risk of postdischarge infection and educated about the signs and symptoms of infection.

Variability of exposure measurements in environmental epidemiology.

In studies in environmental epidemiology, exposure to harmful agents is often highly variable in time and space. It is not usually possible to measure the relevant, personal exposure of study subjects to these agents directly. Instead, exposure measurements are performed at fixed sites and/or for limited periods of time in many cases. Such measurements are imperfect in the sense that they only approximate the "true" personal exposure of study subjects. When measures of exposure are highly variable in time and space, single measurements approximate the true exposure only to a limited extent. The variability of measures of exposure can be investigated by repetition of the measurements in time and space. Analysis of variance techniques can be used to separate the within-subject or "error" variance from the between-subjects or true variance. Computation of the ratio between the error variance and the true variance is a useful technique to evaluate the potential bias in correlation and regression coefficients calculated with these measures of exposure. Using data from a number of different studies, the authors have estimated the variance ratio of lead exposure and nitrogen dioxide exposure variables. The results suggest that these ratios may be large. Empirical illustrations are given of bias in regression coefficients of childhood blood levels on different lead exposure variables. It is recommended that pilot studies be performed more routinely to estimate the magnitude of the variance ratios of exposure variables of interest in studies in environmental epidemiology.