Neutron measurements in the vicinity of a self-shielded PET cyclotron.

The radionuclides used in positron emission tomography (PET) are short-lived and generally must be produced on site using a cyclotron. A common end product of the nuclear reactions used to produce the PET radionuclides is neutron radiation. These neutrons could potentially contribute to the annual effective dose received by hospital personnel. A Bonner sphere spectrometer was used to measure neutron energy spectra at three locations near a self-shielded PET cyclotron. This cyclotron accelerates protons to 11 MeV. The neutron measurements reported were made during the production of 18F via the 18O(p,n)18F reaction (Q = -2.4 MeV). Neutron spectra were obtained with the BUMS unfolding code and converted to dose equivalent rates.

Diagnostic efficacy of posttraumatic symptoms in children exposed to disaster.

Examined 5 conditional probability indices to determine the diagnostic efficacy of 48 symptoms associated with posttraumatic stress disorder (PTSD) in 5,687 children exposed to Hurricane Hugo, of whom 5.5% had a diagnosis of posttraumatic stress syndrome (PTSS). Moderate levels of sensitivity and high levels of specificity were obtained for most symptoms. Odds ratios more precisely demonstrated that some Diagnostic and Statistical Manual of Mental Disorders (DSM) symptoms of PTSD, especially when combined, were useful for identifying children with PTSS but that anxiety symptoms and some DSM symptoms of PTSD had poor diagnostic utility. Satisfying criteria for the DSM-III-R numbing/avoidance cluster and symptoms from the numbing/avoidance cluster had the highest diagnostic efficacy, suggesting that avoidance may be the hallmark of severe posttraumatic reactions. These results suggest which symptoms should be conceptualized as central versus peripheral to the disorder and which symptoms and symptom combinations clinicians should attend to most when diagnosing or screening PTSD in children.

Physiological profiles of elite off-road and road cyclists.

There are minimal scientific data describing international caliber off-road cyclists (mountain bikers), particularly as they compare physiologically with international caliber road cyclists. Elite female (N = 10) and male (N = 10) athletes representing the United States National Off-Road Bicycle Association (NORBA) Cross-Country Team were compared with elite female (N = 10) and male (N = 10) athletes representing the United States Cycling Federation (USCF) National Road Team. Submaximal and maximal exercise responses were evaluated during the "championship" phase of the training year when athletes were in peak condition. All physiological tests were conducted at 1860 m. Among the female athletes, physiological responses at lactate threshold (LT) and during maximal exercise (MAX) were similar between NORBA and USCF cyclists with two exceptions: 1) USCF cyclists demonstrated a significantly greater (P < 0.05) absolute (16%) and relative (10%) maximal aerobic power, and 2) MAX heart rate was significantly higher (P < 0.05) for the USCF athletes (6%). Among the male athletes, physiological responses at LT and MAX were similar between NORBA and USCF cyclists with two exceptions: 1) USCF cyclists produced significantly greater (P < 0.05) absolute (18%) and relative (16%) power at LT, and 2) USCF cyclists produced significantly greater (P < 0.05) absolute (12%) and relative (10%) power at MAX. These data suggest that, in general, elite off-road cyclists possess physiological profiles that are similar to elite road cyclists.

Children exposed to disaster: I. Epidemiology of post-traumatic symptoms and symptom profiles.

OBJECTIVE: To determine the range and severity of post-traumatic stress disorder (PTSD) symptoms exhibited by children after exposure to a natural disaster. METHOD: Three months after Hurricane Hugo struck Berkeley County, South Carolina, 5,687 school-aged children were surveyed about their experiences and reactions related to the storm. Self-reports of PTSD symptoms were obtained by use of a PTSD Reaction Index. RESULTS: Significant variation in the prevalence of PTSD symptoms was found across race, gender, and age groups. Self-reported symptoms were used to derive a post-traumatic stress syndrome classification according to DSM-III-R guidelines for the diagnosis of PTSD. More than 5% of the sample reported sufficient symptoms to be classified as exhibiting this post-traumatic stress syndrome. Females and younger children were more likely to receive this classification. At the symptom level, females reported more symptoms associated with emotional processing and emotional reaction to the trauma. Males were more likely to report symptoms related to cognitive and behavioral factors. Younger children were more likely to report symptoms overall. CONCLUSIONS: Children exposed to a high magnitude natural disaster report sufficient symptoms to establish a DSM-III-R derived classification of a PTSD syndrome. Differences between gender, age, and race groups appear to be related to differential risk of exposure, reporting biases, as well as a differential risk for developing post-traumatic symptoms.

Children exposed to disaster: II. Risk factors for the development of post-traumatic symptomatology.

OBJECTIVE: To examine the influence of subject and exposure variables on the development of post-traumatic stress disorder (PTSD) symptoms and syndrome in children exposed to disaster. METHOD: Three months after Hurricane Hugo, 5,687 school-aged children were surveyed about their experiences and reactions to the hurricane. Self-reports of PTSD symptoms were obtained by use of a PTSD Reaction Index. RESULTS: The presence of PTSD symptoms was strongly related to children's reported severity of the hurricane, degree of home damage sustained, and continued displacement; however, children's level of trait anxiety and their reported emotional reactivity during the hurricane were more strongly related to the presence of PTSD symptoms than were the exposure factors. Different sets of risk factors appeared to differentially influence the development of the three DSM-III-R PTSD symptom clusters. Little evidence for a differential effect of the risk factors between females and males and younger and older children was found. CONCLUSIONS: Level of trait anxiety appears to be the single strongest risk for the development of severe post-traumatic reactions. The higher rate of post-traumatic symptoms in females and younger children in combination with the absence of differential reaction to the risk factors suggests that females and younger children are more likely to develop posttraumatic reactions following a disaster.

A revision of the cytology and ontogeny of several deficiencies in the 3A1-3C6 region of the X chromosome of Drosophila melanogaster.

The cytology and developmental attributes of 18 deficiency mutations in the 3A1-3C6 region of the salivary gland X chromosome of Drosophila melanogaster have been investigated. The cytological limits of several older deficiencies have been revised and clarified and several new deficiencies are characterized. The deficiency mutants, withone possible exception, show a lethal phase in the late embryonic period or the early first larval instar. In contrast, the earliest acting point mutation lethals exposed by these deficiencies generally exhibit a somewhat later, post-embryonic lethality, perhaps indicating that the deficiencies are having some cumulative or synergistic impact on development. However, even with this difference in time of lethality, it is still possibleto conclude that it is not the absolute size of the deficiency but rather the character of the loci delected that determines the impact on development. Observations on the morphology of lethal embryos shows that while this analysis is internally consistent, it does not agree with earlier work. None of the 3A1-3C6 deficiencies causes any major teratologies during embryogenesis. Furthermore, the "earliest acting" gene in this region does not lie in band 3C1 but is most likely associated with bands3A8-10.

Necrotizing enterocolitis--a medical approach to treatment.

Ten cases of necrotizing enterocolitis occurred among 5400 infants delivered consecutively during a two and one-half year period at the Halifax Infirmary. Since this disease involved such extensive areas of the intestinal wall, medical management was employed exclusively, even when intestinal perforation occurred. Nine of the ten infants survived.In this series there was a high incidence of prematurity, prolonged interval between rupture of the placental membranes and delivery, severe asphyxia neonatorum and subsequent hypotension and metabolic acidosis. Blood cultures grew Klebsiella aerobacter or E. coli in 7/10 infants. Only two of these organisms were sensitive to kanamycin and all were resistant to ampicillin. Administration of ampicillin to the mothers did not protect these infants against necrotizing enterocolitis. Edema of the gut wall appeared to be an important early sign. Stricture formation occurred in 4/10 cases, all in the terminal ileum. These infants were operated upon only after the acute stage of the disease had subsided.

Lethality patterns and morphology of selected lethal and semi-lethal mutations in the zeste-white region of Drosophila melanogaster.

Aspects of the developmental genetics of lethal and semi-lethal mutants representing 13 complementation groups (cistrons) in the 3A-3C region of the X chromosome of Drosophila melanogaster are given. Each of these cistrons is associated with a particular chromomere in the salivary gland chromosome. Mutants within each cistron have similar lethality patterns and morphological attributes, and the characteristics of a given cistron are distinct with respect to other cistrons. These results provide additional evidence that only one function is associated with each chromomere.-The results of the lethality pattern analysis are also compared with previous studies of lethal mutants of Drosophila.