Aplicación forense de tecnología radiográfica dental portátil en Argentina: estado actual y perspectivas futuras / Forensic application of portable dental radiographic technology in Argentina: current status and future prospects

Objetivos: Mensurar los niveles de radiación de fuga y dispersión emanada a través de los blindajes y estructuras plomadas del tubo de rayos X de la unidad dental portátil NOMAD, controlando la retrodispersión con el uso del escudo protector de acrílico plomado adaptado en el extremo final del tubo localizador plomado. Se midieron las tasas de exposición dispersadas mediante un detector tipo Geiger-Müller y una cámara de ionización con respuesta en el rango de energías aportadas en diagnóstico por imágenes para la medición de la exposición directa y determinación posterior de las dosis. Se utilizó un fantomas diseñado para diagnóstico odontológico, sopesando la radiación en diferentes angulaciones de operación del equipo NOMAD, simulando los gestos posturales de odontólogos, radiólogos y sujetos a identificar. Se controlaron las tasas de exposición para determinar los valores de las dosis aportadas en las zonas significativas corporales más radiosensibles del operador del equipo. Se obtuvo como resultado que la retrodispersión en el cristalino del ojo del operador fue significativamente menor cuando el fantomas estaba acostado, mientras que a nivel de gónadas resultó más baja con el cuerpo sentado. La tasa de dosis máxima de radiación dispersa que impactó en los operadores fue de 350.8 micro Sieverts por hora (uSv/h) en la zona de gónadas, por cada radiografía tomada sin el uso del delantal de goma plomada, reduciéndose a 4.38 micro Sieverts por hora (uSv/h) al utilizarlo (AU)

High-Field High-Repetition-Rate Sources for the Coherent THz Control of Matter.

Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasi-continuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution.

Studies on the prevalence of leishmanin skin test positivity in the Baringo District, Rift Valley, Kenya.

The leishmanin skin test (LST) was applied in 26 clusters of an average of 97 individuals in Baringo District, Kenya. These clusters were centered around recent cases of visceral leishmaniasis (VL). Of 2,411 individuals tested, 254 (10.5%, 155 males and 99 females) had a positive reaction. Among cured VL patients, the frequency was approximately 30% and no sex difference was observed. In the population as a whole, LST positivity increased with age to a stable level from approximately 15 years of age, reflecting an endemic situation. The level of LST positivity was 25-30% and 10-15% in males and females, respectively. Uninfected household contacts of VL cases had a higher frequency of LST reactivity than the rest of the population. This relationship was significant only in females and children, the prevalence ratio being 2.3 (95% confidence interval 1.3-4.1), 1.9 (1.1-3.5), and 1.4 (0.8-2.5) for females, children, and males, respectively. The frequency of LST positivity was higher individuals living in wood houses than in individuals living in house with mud or stone walls. Again, this difference was significant only in females and children (P = 0.02 and P = 0.04), but not in males (P = 0.7). The results suggest that children and women are exposed to the parasite in or around their houses, whereas adult males are, in addition, exposed elsewhere.

A prospective sero-epidemiological study of visceral leishmaniasis in Baringo District, Rift Valley Province, Kenya.

The incidence of visceral leishmaniasis (VL) was studied in 30 clusters with an average of 98 individuals in each cluster in a defined, endemic rural area of Baringo District, Kenya. The clusters were centred around recent cases of VL. Anti-leishmanial antibodies were measured by the direct agglutination test (DAT) and a clinical examination was performed on 2 occasions between April 1991 and May 1993. Of 2934 individuals tested by the DAT during the first visit, 78 (2.7%) were seropositive, 54 with and 24 without a history of VL. The seroconversion rate was 9/1000 person-years of observation (95% confidence interval 5.1-12.92) among 2332 seronegative individuals retested the following year. During the entire study period, VL was diagnosed in 10 patients, with an incidence rate of 2.2/1000 person-years of observation (95% confidence interval 0.8-3.6). Household contacts of individuals with previously confirmed VL had a higher frequency of DAT positivity than the rest of the population. This difference was significant for both sexes. These results suggest transmission in and around houses.

Visceral leishmaniasis: use of the polymerase chain reaction in an epidemiological study in Baringo District, Kenya.

The polymerase chain reaction was applied to capillary blood spots dried on filter paper from 20 parasitologically proved cases of visceral leishmaniasis (VL), 21 subclinical cases, and 11 healthy controls in a longitudinal study of anthroponotic VL in Baringo District, Kenya. Leishmania deoxyribonucleic acid (DNA) was detected 10.5 months before diagnosis and up to 3 years after diagnosis and apparently successful treatment. Subclinical cases can have detectable circulating parasite DNA in their blood. These findings may indicate that subclinical cases can be a reservoir and formerly treated VL patients can remain a reservoir for a long time. Xenodiagnosis should be performed on subclinical cases and former VL patients to establish their role in transmission of VL in Kenya.

Differential birthweights and the clinical relevance of birthweight standards in a multiethnic society.

Using a computer-stored database, birthweights and related variables over 25,000 infants born in Amsterdam (The Netherlands) were analysed retrospectively. Only after allowing for maternal height, did the difference between mean birthweights of Dutch and Asian infants disappear, whereas Negroid and Mediterranean infants continued to show respectively lower and higher means than the others. These results confirm that the birthweight standards presently used are inappropriate for detection of deviant weight in non-Dutch groups.

[Prevalence of thyroid nodules in 40 years-old or old women]. / Prevalência de nódulos de tireóide detectados por ecografia em mulheres após os 40 anos.

OBJECTIVES: Thyroid nodules constitute a very common clinical problem and the differential diagnosis includes thyroid cancer. As thyroid cancer is rare, it is important to know the prevalence of thyroid nodules in cohorts strongly predisposed to this problem to be able to measure its impact on the health care system, and to devise appropriate diagnostic strategies. The aim of this study was to determine the prevalence of thyroid nodules in women 40 year-old or older by echography. METHODS: Between August 1996 and December 1997, 207 women, 40 year-old or older, were consecutively evaluated by thyroid echography in the Radiology Division of the Hospital de Clínicas de Porto Alegre. Patients who came to the Division to be submitted to thyroid echography were excluded. The mean age of patients studied was 54.7 years (median: 53, range: 40-86 years). One hundred and twenty three patients (54.9%) had a normal thyroid and eighty-two had an abnormal gland (39.6%). Thyroid nodules were detected in seventy-three women (35.3%) and these were larger than 1 cm in 35 women (16.9%). Women without thyroid nodules were younger (53.1 +/-10.7 years) than women with thyroid nodules (58.2 +/-10.6 years) p=0.001; and the prevalence of any thyroid nodule (p=0.001) or nodules larger than 1 cm (p=0.007) increased with age. CONCLUSIONS: Thyroid nodules are very common in women 40 year-old or older, their prevalence increases with age in this cohort and these nodules are potentially palpable (larger than one cm) in one of six women in this age group It is important to have these data in mind when ordering thyroid echographic studies in women 40 year-old or older.

PKU patients on a relaxed diet may be at risk for micronutrient deficiencies.

OBJECTIVE: To investigate micronutrient supply in phenylketonuria (PKU) patients on a relaxed diet. SUBJECTS/METHODS: Sixty-seven patients (6-45 years) with a phenylalanine tolerance ≥ 600 mg/day were included in the study. From a 3-day diet record, protein supply as well as consumption of essential amino acids and several micronutrients were assessed and compared with the current recommendations and data for the healthy population. RESULTS: Protein supply and consumption of all essential amino acids were sufficient in all patients. Supply of micronutrients depended on dietary regime. Patients with a total protein supply of 120% or more of the recommended amount and at least 0.5 g protein per kg body weight from amino-acid mixture (AAM) were sufficiently supplied with all investigated micronutrients. All patients without AAM supplement showed severe micronutrient deficiencies in their diet records. CONCLUSION: PKU patients under a relaxed diet are at risk of an insufficient nutrient supply, if they have first no substitution with AAM, second a protein supply less than 0.5 g per kg body weight from AAM or third a total protein supply less than 120% of the recommendations. Therefore, close monitoring, specific dietary counseling and potential supplementation is mandatory to prevent micronutrient deficiencies in PKU patients.

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH(4)).

BACKGROUND: Since 2008 patients with BH(4)-sensitive phenylketonuria can be treated with sapropterin dihydrochloride (Kuvan®) in addition to the classic phenylalanine (Phe) restricted diet. The aim of this study was to evaluate the nutritional changes and micronutrient supply in patients with phenylketonuria (PKU) under therapy with tetrahydrobiopterin (BH(4)). SUBJECTS AND METHODS: 19 children with PKU (4-18 years) and potential BH(4)-sensitivity were included, 14 completed the study protocol. Dried blood Phe concentrations as well as detailed dietary records were obtained throughout the study at preassigned study days. RESULTS: Eight patients could increase their Phe tolerance from 629 ± 476 mg to 2131 ± 1084 mg (P = 0.006) under BH(4) while maintaining good metabolic control (Phe concentration in dried blood 283 ± 145 µM vs. 304 ± 136 µM, P = 1.0), therefore proving to be BH(4)-sensitive. They decreased their consumption of special low protein products and fruit while increasing their consumption of high protein foods such as processed meat, milk and dairy products. Intake of vitamin D (P = 0.016), iron (P = 0.002), calcium (P = 0.017), iodine (P = 0.005) and zinc (P = 0.046) significantly declined during BH(4) treatment while no differences in energy and macronutrient supply occurred. CONCLUSION: BH(4)-sensitive patients showed good metabolic control under markedly increased Phe consumption. However, the insufficient supply of some micronutrients needs consideration. Long-term multicenter settings with higher sample sizes are necessary to investigate the changes of nutrient intake under BH(4) therapy to further evaluate potential risks of malnutrition. Supplementation may become necessary.

FLUTE: a versatile linac-based THz source.

A new compact versatile linear accelerator named FLUTE is currently being designed at the Karlsruhe Institute of Technology. This paper presents the status of this 42 MeV machine. It will be used to generate strong (several 100 MV/m) ultra-short (~1 ps) THz pulses (up to ~4-25 THz) for photon science experiments, as well as to conduct a variety of accelerator studies. The latter range from comparing different coherent THz radiation generation schemes to compressing electron bunches and studying the electron beam stability. The bunch charge will cover a wide range (~100 pC-3 nC). Later we plan to also produce ultra-short x-ray pulses from the electron bunches, which, for example, could then be combined for THz pump-x-ray probe experiments.

Muon-pair production by atmospheric muons in CosmoALEPH.

Data from a dedicated cosmic ray run of the ALEPH detector were used in a study of muon trident production, i.e., muon pairs produced by muons. Here the overburden and the calorimeters are the target materials while the ALEPH time projection chamber provides the momentum measurements. A theoretical estimate of the muon trident cross section is obtained by developing a Monte Carlo simulation for muon propagation in the overburden and the detector. Two muon trident candidates were found to match the expected theoretical pattern. The observed production rate implies that the nuclear form factor cannot be neglected for muon tridents.

Effects of a supranutritional dose of selenate compared with selenite on insulin sensitivity in type II diabetic dbdb mice.

The present study was performed to examine the mechanism by which selenate ameliorates the insulin sensitivity in type II diabetic dbdb mice. Therefore, 21-adult female dbdb mice were randomly assigned to three experimental groups (0Se, SeIV and SeVI) with seven animals per group. Mice of group 0Se were fed with a selenium-deficient diet (<0.02 mg Se/kg) based on wheat and torula yeast for 8 weeks whereas the mice of groups SeIV (selenite) and SeVI (selenate) were fed with sodium selenite and sodium selenate (up to 35% of the LD(50) for mice in eighth week), in addition to the diet by daily tube feeding. Eight weeks of selenate application led to significantly elevated insulin sensitivity in comparison with selenium deficiency and selenite application. The activity of cytosolic protein tyrosine phosphatases (PTPs) as important negative regulators of insulin signalling was reduced from 53.8% to 22.5% in the liver and skeletal muscle of selenate-treated mice in comparison with the selenium deficient and selenite-treated controls, suggesting an inhibition of PTPs by intermediary selenate metabolites. In an additional in vitro inhibition study, selenate (oxidation state +VI) did not inhibit PTP activity. Selenium metabolites in the oxidation state +IV were found to be the actual inhibitors of PTP activity. In conclusion, the results of the present study show that one possible mechanism by which supranutritional selenate doses enhance insulin sensitivity in type II diabetic dbdb mice is based on the inhibition of PTPS as negative regulators of insulin signalling. Moreover the cellular metabolism of selenate including its intermediary reduction to the oxidation state +IV seems to play a crucial role during this process.

Down-regulation of GPx1 mRNA and the loss of GPx1 activity causes cellular damage in the liver of selenium-deficient rabbits.

The effects of 10 weeks of dietary selenium and/or vitamin E deficiency (< 0.03 mg Se and 1.5 mg vitamin E per kg diet) on body Se and vitamin E stores and on the down-regulation of liver cellular glutathione peroxidase (GPx1) and plasma glutathione peroxidase (GPx3) were examined in growing female New Zealand White rabbits in comparison to Se (+ 0.40 mg Se/kg diet) and/or vitamin E (+ 150 I.U./kg diet) supplemented controls. Additionally plasma lactate dehydrogenase (LDH) activity, liver thiobarbituric acid-reactive substances (TBA-RS) and liver protein carbonyls were measured to assess the development of oxidative stress during an alimentary Se and/or vitamin E deficiency. Significantly decreased concentrations of Se and vitamin E in plasma (Se: - 70%; vitamin E: - 87%) and liver (Se: - 90%; vitamin E: - 95%) indicated an efficacious Se and vitamin E depletion of the rabbits within 10 weeks. GPx1 messenger RNA levels (GPx1 mRNA) in the livers of Se-depleted rabbits were down-regulated to 1/3-1/8 of the Se supplemented controls. GPx1 enzyme activity in the livers of Se-deficient rabbits declined to 10% of the Se-supplied control rabbits. A significantly elevated LDH activity in the blood plasma of Se- and vitamin E-deficient rabbits indicated a general impairment of tissues. Markedly increased TBA-RS concentrations and protein carbonyl contents in the livers of Se- and vitamin E-deficient rabbits gave further evidence for severe oxidative damage of cellular lipids and proteins during an alimentary Se and/or vitamin E deficiency. Both a full expresssion of GPx1 attained by dietary Se supplementation and dietary vitamin E supply effected an almost complete protection against oxidative cellular damage of the liver.

Machakos project studies. Agents affecting health of mother and child in a rural area of Kenya. II. The diagnosis of measles under field conditions.

The measles signs of children reported for measles were recorded on a check list of clinical signs. The presence and absence of these signs for a measles group (M) and a control group (C) were subject of a statistical analysis. The M and C group were determined by the results of laboratory determinations. A prediction score was derived by means of minimal paths analysis, used in reliability networks. The clinical score, based on certain criteria, the prediction score and the result of laboratory determinations were combined in order to reach a final diagnosis. A comparison of the clinical diagnosis and the final diagnosis showed a considerable overlap of the two diagnoses. The conclusion was that the clinical diagnosis only is sufficient to reach adequate incidence rates in the case of a measles epidemic.

Machakos Project Studies: agents affecting health of mother and child in a rural area of Kenya. XVI. The outcome of pregnancy.

The outcome of pregnancy of all women belonging to the study population of the Machakos project studies who delivered during 1975 and 1976 is presented. The birth-rate was 43.0 per 1,000 population per year, the fertility rate was 235 per 1,000 women 15--44 years of age per year. Unexpected low mortality rates were found; stillbirths, neonatal and infant death rates were respectively 29.8 per 1,000 total births and 22.5 and 50.0 per 1,000 live births. One maternal death occurred among the 2,223 deliveries. Maternal age of less than 25 and over 34 years, a history of previous perinatal death and breech delivery were associated with higher perinatal mortality. Parity, marital status, birth-interval and maternal height were not associated with a difference in outcome of pregnancy. The stillbirth rate among the children born in hospital (26.4%) was 4.4% compared with 2.4% among the children born at home, neonatal and infant death rates were the same. Half of all perinatal deaths were caused by either prematurity or birth trauma, 75% of all infant deaths after the first week of life were caused by infections.

PIP: This paper describes the pregnancy outcome of women who delivered in 1975 and 1976 in the area of the Machakos project near Nairobi, Kenya. The study utilized a surveillance system comprising of home visits on 3700 households by 12 fieldworkers. Total number of children born during the study period was 2246. General fertility rate was 235/1000 women of reproductive age. Birth rate was 43.0/1000. There were unexpectedly low mortality rates. Stillbirths were 29.8/1000 total births, neonatal rate, 22.5/1000 total births while infant death rate was 50.0/1000 live births. There was 1 maternal death among the 2223 deliveries. Higher perinatal mortality was attributed to maternal age of less than 25 and over 34 years, a history of previous perinatal death, and breech delivery. Differences in outcome of pregnancy were not affected by parity, marital status, birth interval, and maternal height. Stillbirth rate of hospital-born children (26.4%) was 4.4% compared with 2.4% among children born at home. Half of all perinatal deaths were caused by either prematurity or birth trauma. Infections accounted for 75% of all infant deaths after the first week of life. A subsequent paper will relate the outcome of pregnancy to antenatal and delivery care received.