7-Alkyldeoxyguanosine adduct detection by two-step HPLC and the 32P-postlabeling assay

7-Alkyldeoxyguanosine DNA adducts may be a marker for some N-nitrosocompound exposures and subsequent human cancer risk. A sensitiveand highly specific assay for the detection of 7-methyl-2'-deoxyguanosine-3'-monophosphate(7-methyldGp) and 7-ethyl-2'-deoxyguanosine-3'-monophosphate(7-ethyldGp) has been developed by combining two different HPLCpurification steps with the ³²P-postlabeling assay. We previouslyreported that ion-pair reverse-phase (IP) chromatography coupledwith the ³²P-postlabeling assay detects 7-methyldGp in humanlung, but have found that other nucleotides and unknown adductsco-elute. Thus, weak anion exchange (AE) HPLC was added in tandemwith IP HPLC prior to the ³²P-postlabeling assay. 2'-Deoxyguanosine-3'-monophosphate(dGp) is incorporated into the assay as an internal standardfor the assessment of enzyme labeling efficiency and adductrecovery. The methodology was validated using radiolabeled DNAand liquid scintillation counting, which accounts for adductloss from enzymatic digestion to detection. Levels of 7-ethyldGpalso were correlated with accelerator mass spectrometry. Theoverall adduct recovery with this method was 58% for 7-methyldGpand 98% for 7-ethyldGp. The detection limit for both assaysusing 100 µg of DNA was one adduct in 10⁸ unmodified dGp.7-MethyldGp and 7-ethyldGp levels were determined in ten humanlung samples at levels of 1.4–5.4 and 0.6–3.1 adductsper 10⁷ dGp respectively, and in five human lymphocyte samplesat levels of 5.0–8.3 and 0.3–1.4 adducts per 10⁷dGp respectively. Combining the two HPLC purification stepsand the ³²P-postlabeling assay attains chemical specificity,retains sufficient quantitative sensitivity and should be usefulin human biomonitoring studies.     

Enterovirus surveillance of Italian healthy children

Surveillance of acute flaccid paralysis (AFP) is the golden strategy recommended by the WHO to verify the condition of polio eradication in a country. Because of the difficulty to detect all of the expected AFP cases and to reach the target incidence of 1/100,000 requested by WHO, the surveillance of enteroviruses in the population has been adopted by several countries as an important additional method to verify the absence of wild-poliovirus circulation. To complete the results of AFP surveillance set up in Italy in 1996, we have conducted a wild poliovirus surveillance by examining stool samples from 1551 healthy children aged less than 5 years, collected during the period January 1997 to January 1998. The children were from three cities (Parma, Rome and Bari) located in northern, central and southern Italy. Thirty-nine polioviruses, 72 non-polio enteroviruses and 50 enteric, non-entero (NE), viruses were isolated from stool specimens. Polioviruses identified were nine type 1, seven type 2 and twenty-three type 3. Characterization of isolates by both antigenic and molecular methods showed that all polioviruses were of vaccine origin. As expected, most polioviruses, especially types 2 and 3, presented retromutations known to be associated with loss of the Sabin attenuated phenotype. The results of this study support the data obtained from the active AFP surveillance conducted in Italy in the same period – on the absence of paralytic disease due to wild poliovirus – and altogether demonstrate the effectiveness of the vaccination program.     

The screening of tubal abnormalities in the infertile couple

Purpose: Our goal was to assess, with a prospective study, the role of hysterosalpingo-contrast sonography (HyCoSy) with an echocontrast agent and transvaginal ultrasonography alone in the evaluation of tubal status. Methods: Thirty patients were included in the study. These patients underwent an initial plain transvaginal ultrasound examination the day before the HyCoSy. The findings obtained from both examinations were compared with laparoscopic diagnosis, performed in the same menstrual cycle. Results: The kappa values were 0.48 for patency evaluation and 0.67 for the diagnosis of the presence of at least one patent tube, suggesting a good agreement in both cases between HyCoSy and surgery. HyCoSy had a significantly lower sensitivity (50%), but not a significantly higher specificity (75%), than transvaginal ultrasonography alone in the diagnosis of tubal infertility-related abnormalities such as peritubal adhesions. Conclusions: The study demonstrates that the HyCoSy is a useful test when scheduling the most suitable treatment for infertile couples.     

The screening of embryonic viability in early asymptomatic pregnancy by a single endosonographic scan associated with plasma human chorionic gonadotropin determination

Purpose Our purpose was to assess, with a prospective study with random assignment of the day of the first evaluation, whether a single transvaginal ultrasonographic evaluation together with the determination of plasma hCG levels could be used to screen embryonic viability in early asymptomatic pregnancy.Methods In 260 pregnant women observed from January 1991 to November 1993 with spontaneous pregnancies where the exact date of ovulation was known, a single transvaginal ultrasonographic measurement of gestational sac with determination of plasma hCG levels, transformed to their natural logarithm (lnhCG), was performed. An abnormal result was defined as a value of lnhCG per mean gestational sac below the 95% lower confidence limit of the viable pregnancy group.Results The sensitivity was 31%, with a specificity of 97%.Conclusion The study demonstrates that this method has a poor predictive capacity to distinguish viable pregnancy from nonviable pregnancy with a kappa value less than 0.4.     

A seroepidemiological study of toxoplasma gondii infection in children of northern Greece

The aims of this study were to determine the incidence of toxoplasmosis in children ofthe northern Greece region through the evaluation of serologic examination. Sera of 486 children, aged between 6 months and 15 years, suffering from different clinical entities, were tested for anti-Toxoplasma gondii specific IgG antibodies, using an ELISA (enzyme linked immunosorbent assay) technique. In this survey, a high percentage (11.1 percent) of the hospitalized children reacted positively to this method. Males and females had equal prevalence, 11 percent and 11.2 percent, respectively. Seropositivity rate was higher in children aged between 6 and 10 years old. In conclusion, our results indicate toxoplasma infection is an important public health problem affecting children and adolescents in northern Greece. We believe that the study described here could be considered for inclusion in existing national screening programs for hospitalized children.     

A new shading concept based on natural tooth color applied to direct composite restorations.

OBJECTIVE: Patient demands have prompted manufacturers to improve intrinsic optical properties of resin composites and clinicians to refine application procedures. The aim of this study is to present a shading concept based on colorimetric L*a*b* and contrast ratio data of human dentin and enamel. METHOD AND MATERIALS: Extracted teeth of the A and B Vita shade groups (n = 8 per group) were sectioned according to 2 different planes to measure specific color (using the CIE L*a*b* system) and opacity (contrast ratio). Standardized samples of enamel and dentin shades of a new composite system (Miris, Coltène Whaledent) were submitted to the same colorimetric evaluation for comparison with natural tissues. RESULTS: Comparison of teeth from the Vita groups A and B having the same chroma showed limited variations regarding a* (green to red) and b* (blue to yellow) values; the only significant variation was the increasing b* values (yellow) with increasing chroma (A1 to A4 and B1 to B3). As for dentin contrast ratio, limited differences were reported, while enamel proved to increase in translucency with age (reduced contrast ratio). CONCLUSION: These data served as the foundation of the so-called natural layering concept, which makes use of 2 basic composite masses (dentin and enamel) that optically mimic natural tissues. This concept allows for simplified clinical application and layering of composite, as it uses only 1 universal dentin hue with several chroma levels and 3 enamel types for young, adult, and old patients, each exhibiting specific tints and translucency levels.     

Direct visualization of aorto-coronary bypass grafts by two-dimensional echocardiography: A new clinical application

An attempt was made to assess noninvasively the patency of aorto-coronary bypass grafts by two-dimensional echocardiography (2-D echo) in 21 patients who underwent myocardial revascularization. Fifteen patients had one graft while the other six had two grafts. All 21 patients underwent angiography 6–18 months after operation. A day before angiography a 2-D echo was performed with the aim of visualizing the bypass grafts. In 18 patients with 23 grafts (13 with 1 graft and 5 with 2 grafts) it was possible to visualize the tract of the graft, by 2-D echo; 16 were judged patent on 2-D echo and confirmed by selective angiography, while 5 grafts were considered occluded both on 2-D echo and angiography. The other 2 grafts were considered to be occluded on 2-D echo but angiographic control displayed their patency. In 3 patients 2-D echo failed to visualize grafts that were patent angiographically. These data must be considered preliminary and need validation in a larger number of patients. However it is reasonable to conclude that 2-D echo has a reliable capacity to predict graft patency. Such an application may be of value in sequential control of patients with aorto-coronary bypass surgery, especially when combined with other clinical and/or technical data.     

Prolonged apnea and oxyhemoglobin desaturation in asymptomatic premature infants.

Seventy-eight longitudinal four-channel recordings of heart rate, thoracic impedance, nasal thermistry, and pulse oximetry were performed on 26 asymptomatic premature infants (gestational age, 29.9 +/- 1.58 weeks; birth weight, 1,753 +/- 226 grams; postconceptional age, 34.3 +/- 2.0 weeks; postnatal age, 4.41 +/- 2.40 weeks; all values mean +/- SD). Tracings were scored for central and obstructive apnea, bradycardia, periodic breathing, apnea density, and prolonged apnea. The studies demonstrated 585 episodes (7.41/recording) of oxyhemoglobin desaturation with less than 90%. Recordings had a mean of 16.1 episodes of central apnea, 3.04 episodes of obstructive apnea, and 2.34 episodes of bradycardia. Periodic breathing and short obstructive apneas correlated significantly with the total number of oxyhemoglobin desaturations of less than 80% and 90%. Episodes of prolonged apnea were seen in 20 of 78 recordings. In the latter a significantly higher number of total desaturations (less than 90%), desaturations less than 80% and 90% in association with apnea and with bradycardia, longer desaturations, desaturations during sleep, and isolated bradycardia were observed. Variations in heart rate, thoracic impedance, nasal air flow, and pulse oximetry are associated with episodes of oxyhemoglobin desaturation in asymptomatic premature infants. These infants, although asymptomatic, may be at risk for impaired tissue oxygenation.