Organ Doses Associated with Partial-Body Irradiation with 2.5% Bone Marrow Sparing of the Non-Human Primate: A Retrospective Study

A partial-body irradiation model with approximately 2.5% bone marrow sparing (PBI/BM2.5) was established to determine the radiation dose-response relationships for the prolonged and delayed multi-organ effects of acute radiation exposure. Historically, doses reported to the entire body were assumed to be equal to the prescribed dose at some defined calculation point, and the dose-response relationship for multi-organ injury has been defined relative to the prescribed dose being delivered at this point, e.g., to a point at mid-depth at the level of the xiphoid of the non-human primate (NHP). In this retrospective-dose study, the true distribution of dose within the major organs of the NHP was evaluated, and these doses were related to that at the traditional dose-prescription point. Male rhesus macaques were exposed using the PBI/BM2.5 protocol to a prescribed dose of 10 Gy using 6-MV linear accelerator photons at a rate of 0.80 Gy/min. Point and organ doses were calculated for each NHP from computed tomography (CT) scans using heterogeneous density data. The prescribed dose of 10.0 Gy to a point at midline tissue assuming homogeneous media resulted in 10.28 Gy delivered to the prescription point when calculated using the heterogeneous CT volume of the NHP. Respective mean organ doses to the volumes of nine organs, including the heart, lung, bowel and kidney, were computed. With modern treatment planning systems, utilizing a three-dimensional reconstruction of the NHP's CT images to account for the variations in body shape and size, and using density corrections for each of the tissue types, bone, water, muscle and air, accurate determination of the differences in dose to the NHP can be achieved. Dose and volume statistics can be ascertained for any body structure or organ that has been defined using contouring tools in the planning system. Analysis of the dose delivered to critical organs relative to the total-body target dose will permit a more definitive analysis of organ-specific effects and their respective influence in multiple organ injury.

Antimicrobial activity of submicron glass fibres incorporated as a filler to a dental sealer

Two types of antimicrobial glass fibers containing ZnO and CaO, with diameters ranging from tens of nanometers to 1 µm, were successfully fabricated by a laser spinning technique. The antimicrobial performance was corroborated according to ISO 20743:2013, by using gram-negative (Escherichia coli) and gram-positive (Streptococcus oralis, Streptococcus mutans and Staphylococcus aureus) bacteria, and yeast (Candida krusei) (more than 3 logs of reduction). The metabolic activity and endosomal system of eukaryotic cells were not altered by using eluents of CaO glass submicrometric fibers and ZnO fibers at 1 : 10 dilution as cellular media (viability rates over 70%). A dental material was functionalized by embedding ZnO nanofibers above the percolation threshold (20% wt), creating a three-dimensional (3D) fiber network that added an antimicrobial profile. This new ZnO glass fiber composite is proved non-cytotoxic and preserved the antimicrobial effect after immersion in human saliva. This is the first time that a fiber-reinforced liner with strong antimicrobial-activity has been created to prevent secondary caries. The potential of developing new fiber-reinforced composites (FRCs) with antimicrobial properties opens up an extensive field of dental applications where most important diseases have an infectious origin.

Predicting percentage body fat through waist-to-height ratio (WtHR) in Spanish schoolchildren

OBJECTIVE

To analyse the association between waist-to-height ratio (WtHR) and body fat and to develop predictive adiposity equations that will simplify the diagnosis of obesity in the paediatric age group.

DESIGN

Cross-sectional study conducted in Spain during 2007 and 2008. Anthropometric dimensions were taken according to the International Biology Program. The children were classified as underweight, normal weight, overweight or obese according to national standards of percentage body fat (%BF). WtHR differences among nutritional status categories were evaluated using ANOVA. Correlation analysis and regression analysis were carried out using WtHR as a predictor variable for %BF. A t test was applied to the results obtained by the regression model and by the Siri equation. The degree of agreement between both methods was evaluated by estimating the intra-class correlation coefficient.

SETTING

Elementary and secondary schools in Madrid (Spain).

SUBJECTS

Girls (n 1158) and boys (n 1161) from 6 to 14 years old.

RESULTS

WtHR differed significantly (P < 0.001) depending on nutritional status category. This index was correlated (P < 0.001) with all adiposity indicators. The mean %BF values estimated by the regression model (boys: %BF = 106.50 × WtHR - 28.36; girls: %BF = 89.73 × WtHR - 15.40) did not differ from those obtained by the Siri equation. The intra-class correlation coefficient (0.85 in boys, 0.79 in girls) showed a high degree of concordance between both methods.

CONCLUSIONS

WtHR proved to be an effective method for predicting relative adiposity in 6-14-year-olds. The developed equations can help to simplify the diagnosis of obesity in schoolchildren.

Mechanical performance of a biocompatible biocide soda-lime glass-ceramic

A biocompatible soda-lime glass-ceramic in the SiO2-Na2O-Al2O3-CaO-B2O3 system containing combeite and nepheline as crystalline phases, has been obtained at 750°C by two different routes: (i) pressureless sintering and (ii) Spark Plasma Sintering. The SPS glass-ceramic showed a bending strength, Weibull modulus, and toughness similar values to the cortical human bone. This material had a fatigue limit slightly superior to cortical bone and at least two times higher than commercial dental glass-ceramics and dentine. The in vitro studies indicate that soda-lime glass-ceramic is fully biocompatible. The in vivo studies in beagle jaws showed that implanted SPS rods presented no inflammatory changes in soft tissues surrounding implants in any of the 10 different cases after four months implantation. The radiological analysis indicates no signs of osseointegration lack around implants. Moreover, the biocide activity of SPS glass-ceramic versus Escherichia coli, was found to be >4log indicating that it prevents implant infections. Because of this, the SPS new glass-ceramic is particularly promising for dental applications (inlay, crowns, etc).

A new approach for diffusive sampling based on SPME for occupational exposure assessment

Passive sampling is a well-established methodology for the evaluation of exposures to environmental volatile organic compounds (VOCs). The solid-phase microextraction (SPME) technique is a reliable means of sampling VOCs in air. SPME is also being applied as a passive sampler to determine time-weighted average exposure. The use of SPME as a diffusive sampler was evaluated. The passive sampler is based on the use of a cylindrical diffusion cell (porous hydrophobic polyethylene) with an 80 μm carboxen/polydimethylsiloxane fiber to obtain radial diffusion of the analytes to the sorbent. Standard atmospheres of organic vapors in air were used to determine the experimental uptake rates for toluene and chlorobenzene. Toluene concentrations between 2 and 38 mg/m(3) with sampling times between 15 and 60 min were evaluated, as well as chlorobenzene concentrations between 2 and 47 mg/m(3) with sampling times between 30 and 60 min. The mean diffusive uptake rate was 2.14 mL/min for toluene and 2.57 mL/min for chlorobenzene, and no statistical significant effects of concentration and sampling time were observed under the studied conditions for the two compounds. Relative standard deviation ranged from 2.6 to 6.5%. The performance of the sampler under varying concentrations of toluene was also tested, showing that the sampler reflects the average exposure concentration. Effects of temperature, relative humidity, velocity of the air, back diffusion, competitive adsorption, and the stability of chlorobenzene in the sampler were also studied. Sampler behavior was tested in gas stations, and the results were successfully compared with a 3M-3500 diffusive sampler. The results are promising for using this new SPME device for diffusive monitoring for occupational exposure assessment.

Storage stability of ketones on carbon adsorbents

Activated coconut carbon constitutes the more widely used sorbent for preconcentration of volatile organic compounds in sampling workplace air. Water vapour is always present in the air and its adsorption on the activated carbon surface is a serious drawback, mainly when sampling polar organic compounds, such as ketones. In this case, the recovery of the compounds diminishes; moreover, ketones can be decomposed during storage. Synthetic carbons contain less inorganic impurities and have a lower capacity for water adsorption than coconut charcoal. The aim of this work was to evaluate the storage stability of various ketones (acetone, 2-butanone, 4-methyl-2-pentanone and cyclohexanone) on different activated carbons and to study the effect of adsorbed water vapour under different storage conditions. The effect of storage temperature on extraction efficiencies was significant for each ketone in all the studied sorbents. Recovery was higher when samples were stored at 4 degrees C. The results obtained for storage stability of the studied ketones showed that the performance of synthetic carbons was better than for the coconut charcoals. The water adsorption and the ash content of the carbons can be a measure of the reactive sites that may chemisorb ketones or catalize their decomposition. Anasorb 747 showed good ketone stability at least for 7 days, except for cyclohexanone. After 30-days storage, the stability of the studied ketones was excellent on Carboxen 564. This sorbent had a nearly negligible ash content and the adsorbed water was much lower than for the other sorbents tested.

SPE–GC–MS for the sampling and determination of unmetabolized styrene in urine☆

The urinary excretion of unmetabolized styrene can be a very good indicator for biomonitoring styrene in occupationally exposed people. The use of a new urine sampling system, involving a solid-phase extraction cartridge, offers several advantages for determining styrene. The advantages are especially related to the pre-analytical phase of styrene determination, which may be influenced by many variables. The effect on styrene recovery of sorbent type, eluting solvent, elution volume, elution flow-rate, and the addition of methanol to the washing solvent, was evaluated by experimental design methodology. As a result, Oasis HLB cartridges were selected for urine sampling, as well as 1.5 mL of ethyl acetate at 0.5 mL/min for eluting the retained styrene. These conditions were then applied to the validation of the solid-phase extraction combined with GC-MS method for the sampling and analysis of unmetabolized styrene in urine. The overall uncertainty was in the 12-22% range and the limit of detection was 2.2 microg/L for a 4 mL urine sample. The stability of styrene has been studied both in cartridges and in vials under different storage periods. After 1 month period the styrene stored on cartridges at room temperature remained stable, whereas this is not the case for styrene recovery from vials. The results obtained indicate that on-site solid-phase extraction of urine can provide a simple, accurate and reproducible sampling and analytical method for the biomonitoring of styrene in urine.

Evolution of occupational exposure to environmental levels of aromatic hydrocarbons in service stations

During refuelling, people may easily be exposed to extremely high levels of gasoline vapour for a short time, although such exposure takes on more importance in the case of service station attendants. The volume of gasoline sold in refuelling operations and the ambient temperature can significantly increase the environmental level of benzene, toluene and xylene (BTX) vapours and, subsequently, the occupational risk of service station attendants. This is especially true in the case of benzene, the most important component of gasoline vapours from a toxicological point of view. The European Directive 98/70/EC, limiting the benzene composition of gasoline, and 94/63/EC, concerning the use of vapour recovery systems in the delivery of gasoline to services stations, were applied in Spain from January 2000 and 2002, respectively. In addition, a new limit value for occupational exposure of 3.25 mg/m(3) was fixed for benzene in Directive 97/42/EC, applied from June 2003. However, recent years have seen the growing use of diesel as well as of unleaded and reformulated gasoline. In this study, we analyse the differences found between air concentration levels of BTXs in 2000 and 2003, analysing samples taken from the personal breathing-zone of occupationally exposed workers in service stations. The results are compared with those obtained in a similar study carried out in 1995 (before the new regulations came into force). The study was carried out in two phases. The first phase was carried out in 2000, after application of the new legal regulation limiting the benzene concentration in gasoline. In this case, an occupationally exposed population of 28 service station attendants was sampled in July, with a mean ambient temperature of 30-31 degrees C. In the second phase, 19 exposed subjects were sampled in July 2003, one of the warmest months in recent years with mean temperatures of 35-36 degrees C during the time of exposure monitoring. The results were then compared with those obtained in 1995, for similar summer weather conditions (environmental temperature between 28 and 30 degrees C). A significant relationship between the volume of gasoline sold and the ambient concentration of aromatic hydrocarbons was found for each worker sampled in all three of the years. Furthermore, a significant decrease in the environmental levels of BTXs was observed after January 2000, especially in the case of benzene, with mean time-weighted average concentrations for 8 h of 736 microg/m(3) (range 272-1603) in 1995, 241 microg/m(3) (range 115-453) in 2000 and 163 microg/m(3) (range 36-564) in 2003, despite the high temperatures reached in the last mentioned year.

Urinary benzene determination by SPME/GC–MS

The urinary excretion of the unmetabolized benzene seems to be a very good index for biomonitoring benzene in occupationally exposed people. The use of solid phase microextraction (SPME) offers important advantages for its determination. Several variables can influence the benzene extraction process. Experimental design methodology was used to estimate the influence of the different variables and to evaluate the simultaneous effect of the more significant variables on the benzene extraction. The results showed that sample temperature, sample volume and their interaction were the more significant factors. A model was found that relates the amount of benzene extracted with the studied variables. The more adequate working conditions were: extraction temperature 15 degrees C, incubation time 1 min, extraction time 1 min and 2.5 ml of sample volume. The results indicate that this method is capable of providing sensitive and accurate results for the biomonitoring of benzene in urine.

Application of solid-phase microextraction and gas chromatography–mass spectrometry to the determination of volatile organic compounds in end-exhaled breath samples

Analysis of exhaled air is of particular interest as an indicator of health as well as a tool for the diagnosis of diseases. It is also a very attractive procedure for the biological control of the exposition to hazardous solvents. This kind of analysis presents numerous advantages over other methods, the most important being that it is not an invasive procedure and, therefore, it is well accepted and can be applied to a wide range of compounds. Furthermore, the analysis is simplified since the matrix is less complex that in the case of blood or urine. In spite of these obvious advantages and the good results obtained, analysis of exhaled air is not in daily use, probably due to the fact that there are no normalized systems of sampling, thus making the interpretation of the results difficult. In this paper, a method for the determination of tetrachloroethylene in exhaled air using solid-phase microextraction is presented. This method, which can be applied to other volatile organic compounds, was developed with special emphasis of end-exhaled breath sampling. The sample is collected in a glass tube whose ends are closed once the exhalation is finished. The tube has an orifice sealed with a septum through which the fiber is inserted. Then, the fiber is desorbed in the injector of a gas chromatograph and the analysis is accomplished using mass spectrometry for the identification and quantification of the components. The proposed system avoids the need of complex sampling equipment and allows analysis of the alveolar fraction. Additionally, the system is economical and easy to handle, thus facilitating the development of normalized methods and its routine use in field studies.

Women in transition--menopause and body composition in different populations

Human biology has provided valuable and applicable points of view to contribute towards human welfare, when it has analyzed changes in the transitional phases of the ontogenetic process. The purpose of this presentation coincides with WHO recommendations to study the modifications suffered by the female body during her stage of reproductive aging in different environments. We study and compared three different groups of women living in the cities of Madrid (Spain), Havana (Cuba) and in Tuxpan, a village in the State of Michoacán (Mexico). Three groups differed with respect to their socio-economic levels, food habits, social organization and culture. We used the same anthropometric techniques, recommended by the IBP, and same tools to assess the women's reproductive life, demography and socio-economic condition. All three groups coincidences regarding the remodelation of their thorax, so after 55 years of age their waist-hip ratio surpassed the cut point of 0.80, associated whit higher risk for chronic cardiovascular disorders. However, examined groups differed, for instance, the rural Mexican women altered their bone density earlier, five years before the urban samples. Next, Mexican women of younger ages maintained high levels of their body mass index above the cut point for overweight.

[Ambulatory pediatric surgery: 25 years of experience]

The objectives of this study are: collect 25 years of experience with ambulatory pediatric surgery in The Pediatric Surgery Service of Hospital de Cruces, present the results of a parents-patient satisfaction survey and show the estimated money savings in the last five years. In the period 1973-1997, 19,934 children (56% of the total surgical cases) were operated with ambulatory surgery, and have been grouped in five quinquenia, showing a constant increase of the percentage of ambulatory surgery. General surgery and ENT are the specialities that more frequently uses this type of surgery (72.4% and 68.6% of the surgical cases of each speciality, respectively, in the last ten years). In general surgery inguinal hernia is the most frequent diagnosis with an increase of orchidopexy in the last five years. ENT is doing ambulatory tonsilectomies in the last ten years. The prolonged recovery stay and unanticipated admissions are rare, usually due to vomiting. The parents satisfaction survey shows great acceptancy, although 13% preferred an overnight postoperative stay. The estimated money saved in the last quinquenia has been important.

A comparative study of four coronal obturation materials in endodontic treatment

The aim of this study was to compare, in vitro, the ability of temporary versus permanent materials to seal the access cavity. Eighty human maxillary single-canal teeth were prepared biomechanically and obturated with gutta-percha and an endodontic cement AH Plus, using the warm vertical compaction technique. All access cavities were sealed with 1 of 4 materials (Cavit, Fermit, Tetric, or Dyract). Microleakage was assessed by methylene blue dye penetration. The teeth were submitted to 100 thermocycles, with temperature varying from 0 degree to 55 degrees C. The greatest degree of leakage was observed with the temporary materials (Cavit and Fermit). There was a significant difference (p < 0.05) in leakage between all materials except between Dyract and Tetric. This suggests that it may be more prudent to use a permanent restorative material for provisional restorations to prevent inadequate canal sealing and the resulting risk of fluid penetration.

[Cancellations in pediatric surgery]

Cancellations have an important role in the effectiveness of the surgical schedule.

OBJECTIVE

Analyze the evolution of the cancellations during the years 1994-1997, after institution of several corrective measures.

MATERIAL AND METHOD

We started in 1994 together with the Quality Unit of the Hospital, a program to reduce surgical cancellations. It consisted in improvement of parents information, surgical schedule centralization, and increasing the awareness of the importance of constant improvement. Cancellations have been divided in: inevitables and inevitables, and analyzed for the entire Service and for each speciality.

RESULTS

A significant reduction of cancellations have been obtain (from 12.38% in 1992 to 3.35% in 1997). The inevitable causes (no presentation, inadequate preparation and lack of time in the surgical room) have shown the most improvement. Although the inevitable causes (intercurrent disease) were also significantly improved, after obtaining prior information of the health of the child, by telephone call or parents advise. ENT is the speciality with greatest improvement by significant reduction of the non presentation and intercurrent disease.

CONCLUSION

After corrective measures conjointly with a realistic surgical schedule, prior telephone call and improvement quality concept, have permitted a significant reduction of cancellations.

Evaluation of environmental levels of aromatic hydrocarbons in gasoline service stations by gas chromatography

The volume of gasoline sold in refuelling operations and the ambient temperature, can increase significantly the environmental levels of aromatic hydrocarbon vapours and subsequently, the occupational risk of gasoline service station attendants, specially in the case of benzene. We have evaluated the occupational exposure to aromatic hydrocarbons by means of personal-breathing-zone samples of gasoline vapours in a service station attendant population. This evaluation was carried out using diffusive samplers, in two periods at quite different temperatures (March and July). A significant relationship between the volume of gasoline sold during the shift and the ambient concentration of benzene, toluene, and xylenes was found for each worker sampled. Furthermore a significant difference was found between the time-weighted average concentration of aromatic compounds measured in March, with ambient temperatures of 14-15 degrees C and July, with temperatures of 28-30 degrees C. In addition, 20% of the population sampled in the last period were exposed to a time-weighted average concentration of benzene above the proposed Threshold Limit Value of 960 micrograms/m(3) of the American Conference of Governmental Industrial Hygienists (ACGIH).

New surgical concepts: nasal tip function

Since the birth of plastic surgery, rhinoplasty has been an outstanding chapter. Facial balance has been endeavoured with two parameters: size and shape. Now, however, the criterion for harmony has involved two more parameters; position and function. Position is related to other facial elements, such as, upper maxilla, upper lip, forehead, and frontonasal sulcus. Function is important because nasal superficial musculoaponeurotic system (SMAS) muscles are important for Nasal tip movement. To understand this better, we must analyze the nasal SMAS, which consists of primary or intrinsic and secondary or extrinsic muscles. When the extrinsics contract, they allow function of the intrinsics. They are the ala nasalis dilator, the ala nasalis elevator, the tranversus, and the tip depressor. Obvious hypertrophies of the dilator and the elevator has been observed in young athletes. Our method combines conventional, new, and modern aspects. It is conventional because the alar cartilages have been completely freed by intercartilaginous and marginal approaches, and the upper or lower border trimmed according to the case. It is more important to measure how much cartilage is left, than how much is removed. The new aspect is consideration of nasal SMAS to treat short noses that display a tendency to descend with laughter, and the modern aspect is the evaluation of dynamic surgical results, apart from the static.

Biological monitoring of occupational exposure to isoflurane by measurement of isoflurane exhaled breath

The relationship between isoflurane environmental concentrations in operating rooms and the corresponding isoflurane concentration in the exhaled air of the operating personnel at the end of the exposure has been investigated. Isoflurane was retained in an adsorbent cartridge and after thermal desorption the concentration was estimated by gas chromatography. Significant correlation between environmental and exhaled air isoflurane concentrations allowed the establishment of a biological exposure index and biological exposure limits corresponding to proposed atmospheric threshold values.

Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle

Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae-negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.

Prevalence and characteristics of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy cattle

From February to July of 1994, 328 faecal samples from 32 herds were collected and verotoxin-producing Escherichia coli (VTEC) found on 84% of the farms. The proportion of animals infected varied from 0-63%. VTEC were recovered from 52 (20%) of 257 cows and from 16 (23%) of 71 calves. Although the VTEC belonged to 25 different serogroups, 7 (O8, O20, O22, O77, O113, O126 and O162) accounted for 46% of strains. Nearly 45% of the strains. Nearly 45% of the 83 bovine VTEC strains belonged to serogroups associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. However, only 2 (2%) of 83 VTEC strains isolated from cattle belonged to enterohaemorrhagic E. coli (EHEC) serotypes (O26:H11 and O157:H7), and only 8 (10%) were positive for the attaching and effacing E. coli (eae) gene sequence. Polymerase chain reaction (PCR) showed that 17 (20%) of VTEC strains carried VT1 genes, 43 (52%) possessed VT2 genes, and 23 (28%) carried both VT1 and VT2 genes. Characterization of VTEC isolates revelated a heterogeneous population in terms of serogroup and toxin type in the positive herds. This study confirms that healthy cattle are a reservoir of VTEC, but, the absence of eae genes in most bovine VTEC strains suggests that they may be less virulent for humans than eae-positive EHEC.

Detection of enterohaemorrhagic Escherichia coli O157:H7 in minced beef using immunomagnetic separation

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 has been recently recognized as a human pathogen associated with haemorrhagic colitis and haemolytic uraemic syndrome. Most outbreaks of haemorrhagic colitis resulted from the consumption of undercooked minced beef or raw milk. Dairy cattle have been identified as a reservoir of EHEC O157: H7. In this study E. coli O157 specific antibody, coated on magnetic beads, was used to concentrate and release EHEC O157:H7 from meat samples. A survey of retail fresh minced beef and hamburger samples using this procedure revealed that 3 (5%) of 58 beef samples were positive for EHEC O157:H7. Two of the strains produced both VT1 and VT2 verotoxins, and one produced only VT2. Immunomagnetic separation is a sensitive and simple technique for the isolation of E. coli O157 from food, and could be useful for a further elucidation of the epidemiology of this organism. The relatively high prevalence of EHEC O157:H7 in beef samples may constitute a risk for public health. Thus, a suitable epidemiologic control and effective methods of prevention should be applied.

Purge-and-trap method for the determination of styrene in urine

A purge-and-trap method for biological monitoring of styrene in urine was developed. Sorbent tubes packed with Tenax TA were used to trap styrene vapour purged from urine. Thermal desorption-gas chromatography was used for sorbent tubes analysis. The detection limit (0.70 micrograms/1), linearity range, recovery (> 94% for spiked urine samples) and repeatability for urine from occupational exposed workers show the suitability of the method for the determination of styrene in urine. One specific advantage of this method is the possibility of storage of the charged sorbent tubes during long periods of time without a significant loss of styrene. This approach can be used, with slight modifications, for urinary determination of several others organic contaminants commonly present in occupational exposures.

Dentin bond strength of fluoride-releasing materials

PURPOSE

To evaluate the shear bond strength to dentin of fluoride-releasing materials.

MATERIALS AND METHODS

Human, noncarious extracted permanent molars stored in distilled water were used. Flat buccal and lingual dentin surfaces were ground wet on 600-grit silicon carbide paper. The teeth were then distributed at random into four groups of 5 teeth (10 surfaces) each: Group 1: Fuji II LC; Group 2: Vitremer; Group 3: VariGlass; Group 4: Dyract. Cylindrical samples of the glass ionomers were prepared in plastic molds and bonded to the dentin surface according to the manufacturers' instructions. All samples were placed in distilled water for 24 hours, thermocycled for 500 cycles in distilled water at 5 degrees C and 55 degrees C and sheared with an Instron at a crosshead speed of 0.5 mm/minute.

RESULTS

In MPa: Group 1: 15.96 +/- 3.28; Group 2: 9.70 +/- 2.43; Group 3: 13.48 +/- 3.35; Group 4: 21.14 +/- 5.32. ANOVA revealed that Dyract had a significantly higher bond strength than all the other products tested (P < 0.0001). Vitremer had a significantly lower bond strength. Fuji II LC had no significant difference from VariGlass. Fracture patterns, examined with the SEM, were cohesive within the cement for all groups.

Application of thermal desorption to the biological monitoring of organic compounds in exhaled breath

We have developed a thermal desorption-gas chromatographic method for the analysis of organic compounds in exhaled breath air, to be used in the biological monitoring of environmental exposure. The exhaled breath sampler is based on the concentration of compounds present in alveolar air in a solid sorbent material. Isoflurane (1-chloro-2,2,2-trifluoroethyl-difluoromethyl-ether), an inhaled anaesthetic used widely in surgery, and styrene, used in boat construction and the manufacture of fibreglass-reinforced plastics, are partially eliminated from the body in exhaled breath, samples of which can therefore be used to monitor biological exposure to these two organic compounds. Recoveries were tested in controlled atmospheres of isoflurane or styrene, with Chromosorb 106 or Tenax, respectively, as the adsorbent. We also investigated the influence of relative humidity, an important factor in breath sampling, on adsorption.

Biochemical characterization of CD26 (dipeptidyl peptidase IV): Functional comparison of distinct epitopes recognized by various anti-CD26 monoclonal antibodies

In this paper, we performed further biochemical characterization of the CD26 antigen, as defined by the mAbs in anti-1F7 and anti-Ta1, in order to clarify the observed functional differences among these mAbs. For this purpose, we developed a mAb, anti-5F8, which recognizes yet another epitope on the CD26 antigen different from that recognized by anti-1F7 and anti-Ta1 and compared their respective effect on T cell activation as well as the structures recognized by these mAbs. Functionally, anti-5F8 did not exhibit a comitogenic effect on T cell activation via the CD3 and CD2 pathways. Peptide mapping studies suggested that the 110 kDa molecules precipitated by these mAbs are identical. We showed that the 110 kDa CD26 structure on human T cells is composed of a family of heterogeneous molecules, as determined by isoelectric focusing studies. In addition, we demonstrated that the CD26 antigen has a DPPIV enzyme activity and this enzyme activity is found only on the principal basic structure of CD26 but not on the additional acidic structures. Biochemical studies also revealed that these mAbs recognized distinct epitopes on the CD26 antigen. Pulse-chase studies showed the the 1F7 epitope was found on both the immature (100 kDa) and mature (110 kDa) forms of the CD26 antigen. On the other hand, the Ta1 and 5F8 epitopes were expressed mainly on the mature form of the CD26 antigen. Moreover, anti-IF7 consistently precipitated an additional 43 kDa molecule in association with the principal 110 kDa molecule. Taken together, these data suggested that the additional 43 kDa structure or the distinct epitope recognized by anti-IF7 may play a role in human T cell activation via the CD3 and CD2 pathways.

Cell surface modulation of CD26 by anti-1F7 monoclonal antibody. Analysis of surface expression and human T cell activation

In this paper, we examined in detail the ability of anti-1F7 to modulate 1F7 (CD26) surface expression as well as analyzed the functional relationship between the surface expression of CD3, CD2, and CD26 and human T cell activation. We showed that anti-1F7-induced modulation is an energy-dependent process that occurs via capping and internalization of the Ag-antibody complex. Although the recovery rate for Ag reexpression of 1F7 following optimal modulation is relatively delayed, reexpression of 1F7 is greatly accelerated following phorbol ester treatment. Most importantly, we demonstrated that modulation of the CD26 Ag leads to an enhancement in the proliferative activity of modulated human T cells treated with anti-CD3 or anti-CD2, which is preceded by an enhancement in Ca2+ mobilization. CD26 modulation also led to an increase in anti-CD3- or anti-CD2-mediated T cell clone proliferation. Finally, whereas modulation of the CD26 Ag has an effect on CD3- or CD2-induced T cell activation, modulation of the CD3/TCR complex inhibits the proliferative response of T cells incubated with anti-CD3 plus anti-1F7 or anti-CD2 plus anti-1F7. However, modulation of the CD2 structure does not affect anti-CD3- plus anti-1F7-induced human T cell activation. The above results thus provide additional evidence that the CD26 Ag plays an integral role in the regulation of human T cell activation.

Cell surface modulation of CD26 by anti-1F7 monoclonal antibody. Analysis of surface expression and human T cell activation

In this paper, we examined in detail the ability of anti-1F7 to modulate 1F7 (CD26) surface expression as well as analyzed the functional relationship between the surface expression of CD3, CD2, and CD26 and human T cell activation. We showed that anti-1F7-induced modulation is an energy-dependent process that occurs via capping and internalization of the Ag-antibody complex. Although the recovery rate for Ag reexpression of 1F7 following optimal modulation is relatively delayed, reexpression of 1F7 is greatly accelerated following phorbol ester treatment. Most importantly, we demonstrated that modulation of the CD26 Ag leads to an enhancement in the proliferative activity of modulated human T cells treated with anti-CD3 or anti-CD2, which is preceded by an enhancement in Ca2+ mobilization. CD26 modulation also led to an increase in anti-CD3- or anti-CD2-mediated T cell clone proliferation. Finally, whereas modulation of the CD26 Ag has an effect on CD3- or CD2-induced T cell activation, modulation of the CD3/TCR complex inhibits the proliferative response of T cells incubated with anti-CD3 plus anti-1F7 or anti-CD2 plus anti-1F7. However, modulation of the CD2 structure does not affect anti-CD3- plus anti-1F7-induced human T cell activation. The above results thus provide additional evidence that the CD26 Ag plays an integral role in the regulation of human T cell activation.

[Pit sealing of deciduous and permanent molars. In vivo evaluation]

The authors studied a fissure sealant retention in deciduous molars and first permanent molars. The assessment of the sealant retention was performed at six months intervals. After eighteen months study period a greater sealant on the deciduous molars was observed, in a decreasing order as follow: upper and lower first permanent molars. It was also shown that greatest loss of sealant occurred on the disto occlusal pit of the upper first permanent molars.

[Penoscrotal inversion]

A case of a child with complete penoscrotal transposition is presented. Surgical correction was performed in two stages. First, we performed penile elongation with scrotoplasty and partial perineal urethroplasty with the Thiersch Duplay technique, followed by Byars urethroplasty. The surgical techniques commonly used to correct this anomaly and their indications are reviewed. Currently, we recommend correction of hypospadias and transposition in a single stage procedure whenever possible.

[Digestive intolerance in newborn infants with extensive intestinal resections. Nutritional problems and long-term sequelae]

The experience of two neonates with extensive intestinal resection and severe difficulties in the introduction of oral nutrients in presented. The pathophysiology and treatment of short bowel syndrome is reviewed, emphasizing the importance of maintenance of nutritional support as well as the factors that contribute to the readaptation mechanism. Mention is made of the complications and long-term sequelae encountered in these cases, whose body weights and growth were normal at the age of 5.

Secular change in menarche in women in Madrid

The age at menarche was estimated by recollection in 1617 women between the ages of 18 and 60 in Madrid and a nearby suburb, Pinto. The population of Pinto is working-class and the Madrid group, taken from residential neighbourhoods , belongs to the upper middle class. In both groups we found a diminution in average age at menarche, from 14.04 to 13.02 years in Madrid and from 14.55 to 13.16 years from about 1935 to about 1965 in Pinto. These changes have been more intense in the group which is less well-off economically, where living conditions have varied much more drastically.