X-ray attenuation models to account for beam hardening in computed tomography.

We introduce a beam-hardening correction method for lab-based X-ray computed tomography (CT) by modifying existing iterative tomographic reconstruction algorithms. Our method simplifies the standard Alvarez-Macovski X-ray attenuation model [Phys. Med. Biol.21, 733 (1976)] and is compatible with conventional (i.e., single-spectrum) CT scans. The sole modification involves a polychromatic projection operation, which is equivalent to applying a weighting that more closely matches the attenuation of polychromatic X-rays. Practicality is a priority, so we only require information about the X-ray spectrum and some constants relating to material properties. No other changes to the experimental setup or the iterative algorithms are necessary. Using reconstructions of simulations and several large experimental datasets, we show that this method is able to remove or reduce cupping, streaking, and other artefacts from X-ray beam hardening and improve the self-consistency of projected attenuation in CT. When the assumptions made in the simplifications are valid, the reconstructed tomogram can even be quantitative.

Intraspecific variability of popcorn S7 lines for phosphorus efficiency in the soil.

The expansion of agriculture, coupled with the need for sustainable cropping, is one of the greatest challenges of the scientific community working on the generation of new cultivars adapted to abiotic stress conditions. The aim of this study was to evaluate the variability of popcorn lines as to responsiveness and efficiency in phosphorus use, as a first step towards the implementation of a breeding program interested in the practice of sustainable agriculture. Twenty-five popcorn lines were evaluated in two locations with different phosphorus levels in the soil, using a randomized block design. The following traits were measured: plant height, ear height, female flowering date, male flowering date, male-female flowering interval, ear diameter, ear length, 100-grain weight, grain yield, popping expansion, and expanded popcorn volume per hectare. A combined analysis of variance and test of means were performed, and the lines were classified as to their phosphorus use efficiency, according to their production performance in the different environments. The genetic diversity between the lines was estimated by Tocher's and UPGMA clustering methods, using generalized Mahalanobis distance. Lines L59, P7, P2, P3, P4, P8, P10, P9, L66, L70, L69, and P5 were efficient and responsive, whereas lines L75, L80, L61, L77, L63, L65, P1, L54, L53, L88, and L71 were inefficient and nonresponsive. Genetic variability was greater in the environments with low phosphorus in the soil, suggesting that the selection pressure exerted in the stressing environment is a decisive factor to obtain a higher expression of variability.

Prenatal methyl mercury exposure in relation to neurodevelopment and behavior at 19 years of age in the Seychelles Child Development Study.

BACKGROUND: Fish are important sources of protein and contain a variety of nutrients, such as n-3 long-chain polyunsaturated fatty acids (PUFA), essential for normal brain development. Nevertheless, all fish also contain methyl mercury (MeHg), a known neurotoxicant in adequate dosage. Our studies of the Seychelles Child Development Study (SCDS) Main Cohort enrolled in 1989-1990 (n=779) have found no consistent pattern of adverse MeHg effects at exposures achieved by daily fish consumption. Rather, we have observed evidence of improved performance on some cognitive endpoints as prenatal MeHg exposure increases in the range studied. These observations cannot be related to MeHg and may reflect the role of unmeasured covariates such as essential nutrients present in fish. To determine if these associations persist into young adulthood, we examined the relationship between prenatal MeHg exposure, recent PUFA exposure and subjects' neurodevelopment and behavior at 19 years of age. METHODS: We examined 533 participants using the following test battery: the Profile of Mood States-Bipolar (POMS-Bi); Finger Tapping; Kaufman Brief Intelligence Test (K-BIT); measures of Fine Motor Control and Complex Perceptual Motor Control; and Visual Spatial Contrast Sensitivity. We collected the following covariates: maternal IQ, family life course stressors, socioeconomic status, and subjects' recent postnatal MeHg, sex, and computer use. Primary analyses (based on N=392-475) examined covariate-adjusted associations in multiple linear regression models with prenatal MeHg as the primary exposure measure. Secondary analyses additionally adjusted for total n-6 and fish-related n-3 PUFA measured in the subjects' serum at the 19-year examination. RESULTS: Study participants had a mean prenatal MeHg exposure of 6.9 ppm, and a mean recent postnatal exposure of 10.3 ppm. There were no adverse associations between prenatal MeHg and any of the measured endpoints. For recent postnatal MeHg exposure, however, adverse associations were observed for Finger Tapping (non-dominant hand) among women and for the K-BIT Matrices for both sexes, with or without adjustment for PUFA. CONCLUSION: Our findings continue to provide no evidence for an adverse effect of prenatal MeHg exposure on development in a cohort that consumes fish daily. Observations for postnatal MeHg exposure will need to be confirmed using more comprehensive exposure measures.

Comparable outcome of alternative donor and matched sibling donor hematopoietic stem cell transplant for children with acute lymphoblastic leukemia in first or second remission using alemtuzumab in a myeloablative conditioning regimen.

HLA-matched sibling donor (MSD) stem cell transplantation can cure>60% of pediatric patients with acute lymphoblastic leukemia (ALL), but <30% of patients will have a sibling donor. Alternative donor (AD) transplantation can be curative but has a higher risk of graft-versus-host disease (GVHD). The addition of alemtuzumab (Campath 1-H) to AD transplants produces in vivo T cell depletion, which may reduce the risk for GVHD. We now report the outcome for 83 children with ALL (41 MSD, 42 AD) undergoing stem cell transplantation in first or second complete remission. All patients received myeloablative conditioning, including cyclophosphamide, cytarabine arabinoside, and total-body irradiation, with alemtuzumab administered to AD recipients. GVHD prophylaxis consisted of a calcineurin inhibitor with either short-course methotrexate or prednisone. Disease-free survival (DFS) for MSD recipients was 72.3% (95% confidence interval [CI], 55.4%-83.6%) versus 62.4% (95% CI, 45.2%-75.4%) for AD recipients. The 100-day mortality was 7.1% in the AD group and 2.4% in the MSD group. Relapse rates were identical (24%). Treatment-related mortality, principally viral infection, explained the difference in survival. For children undergoing stem cell transplantation (SCT) from alternative donors, alemtuzumab with a myeloablative conditioning regimen resulted in DFS comparable to MSD.

Use of autologous blood as part of the perfusate for cardiopulmonary bypass: a priming technique.

In an attempt to replace the oncotic and protein coating capabilities of serum albumin in the perfusate, we established a priming protocol that used autologous blood as part of the perfusate solution. Prior to March 1, 1999, our standard priming protocol was 1650 ml of crystalloid with 250 ml of 5% serum albumin and 5,000 units of heparin. After removing albumin from our prime, our standard protocol was altered to include 40 ml of the patient's autologous blood in 1,800 ml of crystalloid and 10,000 units of heparin. To determine the intraoperative effects of using albumin/crystalloid primes (Group A), autologous blood/crystalloid primes (Group B) and crystalloid primes (Group C), a total of 178 patients were sequentially evaluated. Intraoperative parameters evaluated were total protein (TP), colloid osmotic pressure (COP), platelets (Plts) and fluid requirements during cardiopulmonary bypass (CPB). During an overlapping 12-month period of time, 1,092 consecutive cardiac surgical cases using CPB (584 albumin prime; 508 autologous blood prime) were evaluated for clinical outcomes in terms of mortality and length of hospitalization. In addition, over a period of 15 months, 1,458 patients in both the autologous blood/crystalloid group and the crystalloid only group were evaluated for the incidence of high-pressure excursions (HPE) after going on bypass. Comparative reviews of TP, COP and Plts demonstrated no significant difference 10 min after the start of bypass between Groups A and B. However, in Group C, there was a statistically significant increase in the intraoperative fluid requirements during CPB, compared to both of the other groups. There was no significant difference in the incidence of HPE, with an occurrence of 1.04% in the crystalloid only group and 1.11% in the autologous blood/crystalloid group. Autologous blood perfusates were identical to albumin perfusates in their platelet protection and reduction of fluid shifts during the intraoperative period.

An outbreak of hepatitis A associated with green onions.

Forty-three cases of serologically confirmed hepatitis A occurred among individuals who ate at restaurant A in Ohio in 1998. Serum samples from all restaurant A employees who worked during the exposure period were negative for IgM antibodies to hepatitis A virus (HAV). A matched case-control study determined that foods containing green onions, which were eaten by 38 (95%) of 40 case patients compared with 30 (50%) of 60 control subjects, were associated with illness (matched odds ratio, 12.7; 95% confidence interval, 2.6-60.8). Genetic sequences of viral isolates from 14 case patients were identical to each other and to those of viral isolates from 3 patients with cases of hepatitis A acquired in Mexico. Although the implicated green onions, which could have come from one of 2 Mexican farms or from a Californian farm, were widely distributed, no additional green onion-associated cases were detected. More sensitive methods are needed to detect foodborne hepatitis A. A better understanding of how HAV might contaminate raw produce would aid in developing prevention strategies.

A comparison of serum total cholesterol levels and their determinants between the Federal Republic of Germany and the United States.

Mean serum total cholesterol levels appear to be higher in the Federal Republic of Germany (FRG) than in the United States (US) while coronary heart disease death rates are lower. The study examined possible factors for the difference including possible differences in laboratory methodology. Cross-sectional data from the first two waves of the German National Health Surveys (1984-1986 and 1987-1989; n = 9709) and from the Second National Health and Nutrition Examination Survey (1976-1980; n = 7832) were compared for men and women 25-69 years of age. The influence of age, body mass index, diet, cigarette smoking, education, income, use of oral contraceptives or antihypertensive agents, alcohol consumption and potential differences in laboratory measurement were explored using multiple regression techniques separately for men and women for ages 25-39, 40-59 and 60-69 years of age. Overall ages, unadjusted mean total cholesterol levels were higher in German than US men (6.02 vs. 5.64 mmol/l) and in German than US women (6.04 vs. 5.80 mmol/l) as were HDL cholesterol levels (men: 1.30 vs 1.14 mmol/l; women: 1.65 vs. 1.38 mmol/l). Adjusting for lifestyle factors explained, on the average, 40% of the differences in mean total cholesterol of which half or 20% was accounted for by adjusting for alcohol intake. Adjusting for possible laboratory differences explained, on the average, an additional 30% of the differences. Frequency of alcohol intake was the most important factor in explaining differences in mean HDL cholesterol levels. Adjustment for differences in alcohol intake had negligible effects on reducing the differences in mean non-HDL cholesterol.

Recombinant, chimaeric live, attenuated vaccine (ChimeriVax) incorporating the envelope genes of Japanese encephalitis (SA14-14-2) virus and the capsid and nonstructural genes of yellow fever (17D) virus is safe, immunogenic and protective in non-human primates.

Yellow fever 17D virus, a safe and effective live, attenuated vaccine, was used as a vector for genes encoding the protective antigenic determinants of a heterologous member of the genus Flavivirus, Japanese encephalitis (JE) virus, the leading cause of acute viral central nervous system infection and death throughout Asia. The viral envelope (prM and E) genes of a full-length cDNA clone of YF 17D virus were replaced with the corresponding genes of JE SA14-14-2, a strain licensed as a live, attenuated vaccine in China. Full-length RNA transcripts of the YF/JE chimaera were used to transfect Vero cells. The progeny virus (named 'ChimeriVax-JE'), was used to define safety after intracerebral (i.c.) inoculation of rhesus monkeys. Monkeys (N = 3) inoculated with a high dose (6.6 log10 pfu) developed a brief viremia, showed no signs of illness, developed high titers of anti-JE neutralizing antibody, and had minimal brain and spinal cord lesion scores according to criteria specified in the WHO monkey neurovirulence test. A control group of 3 monkeys that received a lower dose (4.2 log10 pfu) of commercial YF 17D vaccine had slightly higher lesion scores. To develop a lethal monkey model of JE for vaccine protection tests, we inoculated groups of monkeys i.c. or intranasally (i.n.) with a JE virus strain found to be highly neurovirulent and neuroinvasive for mice. Monkeys inoculated i.c., but not i.n., developed severe encephalitis after an incubation period of 8-13 days. The ChimeriVax-JE virus was passed in a cell line acceptable for human use (diploid fetal rhesus lung) and 4.3 or 5.3 log10 pfu were inoculated into groups of 3 monkeys by the subcutaneous route. All 6 animals developed brief viremias (peak titer < 2.0 log10 pfu/ml) and subsequently had anti-JE but no yellow fever neutralizing antibodies. On day 64, the monkeys were challenged i.c. with 5.5 log10 pfu of virulent JE virus. The immunized animals had no detectable viremia post-challenge, whereas 4 unimmunized controls became viremic. Only 1 of 6 (17%) vaccinated monkeys but 4 of 4 (100%) unvaccinated controls developed encephalitis. Histopathological examination 30 days after challenge confirmed that the protected, immunized animals had no or minimal evidence of encephalitis. These data demonstrated the ability of the ChimeriVax-JE to induce a rapid humoral immune response and to protect against a very severe, direct intracerebral virus challenge. Target areas of neuronal damage and inflammation in monkeys infected IC with wild-type JE, the chimaeric virus and YF 17D were similar, indicating that the histopathological scoring system used for the WHO yellow fever monkey neurovirulence test will be applicable to control testing of chimaeric seed viruses and vaccines.

Region-specific astrogliosis in brains of mice heterozygous for mutations in the neurofibromatosis type 1 (Nf1) tumor suppressor.

Brains from human neurofibromatosis type 1 (NF1) patients show increased expression of glial fibrillary acidic protein (GFAP), consistent with activation of astrocytes (M.L. Nordlund, T.A. Rizvi, C.I. Brannan, N. Ratner, Neurofibromin expression and astrogliosis in neurofibromatosis (type 1) brains, J. Neuropathol. Exp. Neurology 54 (1995) 588-600). We analyzed brains from transgenic mice in which the Nf1 gene was targeted by homologous recombination. We show here that, in all heterozygous mice analyzed, there are increased numbers of astrocytes expressing high levels of GFAP in medial regions of the periaqueductal gray and in the nucleus accumbens. More subtle, but significant, changes in the number of GFAP positive astrocytes were observed in the hippocampus in 60% of mutant mice analyzed. Astrocytes with elevated GFAP were present at 1 month, 2 months, 6 months and 12 months after birth. Most brain regions, including the cerebellum, basal ganglia, cerebral cortex, hypothalamus, thalamus, cortical amygdaloid area, and white matter tracts did not show any gliotic changes. No evidence of degenerating neurons was found using de Olmos' cupric silver stain. We conclude that Nf1/nf1 mice provide a model to study astrogliosis associated with neurofibromatosis type 1.

Early metabolic alterations in edematous perihematomal brain regions following experimental intracerebral hemorrhage.

OBJECT: The authors previously demonstrated, in a large-animal intracerebral hemorrhage (ICH) model, that markedly edematous ("translucent") white matter regions (> 10% increases in water contents) containing high levels of clot-derived plasma proteins rapidly develop adjacent to hematomas. The goal of the present study was to determine the concentrations of high-energy phosphate, carbohydrate substrate, and lactate in these and other perihematomal white and gray matter regions during the early hours following experimental ICH. METHODS: The authors infused autologous blood (1.7 ml) into frontal lobe white matter in a physiologically controlled model in pigs (weighing approximately 7 kg each) and froze their brains in situ at 1, 3, 5, or 8 hours postinfusion. Adenosine triphosphate (ATP), phosphocreatine (PCr), glycogen, glucose, lactate, and water contents were then measured in white and gray matter located ipsi- and contralateral to the hematomas, and metabolite concentrations in edematous brain regions were corrected for dilution. In markedly edematous white matter, glycogen and glucose concentrations increased two- to fivefold compared with control during 8 hours postinfusion. Similarly, PCr levels increased several-fold by 5 hours, whereas, except for a moderate decrease at 1 hour, ATP remained unchanged. Lactate was markedly increased (approximately 20 micromol/g) at all times. In gyral gray matter overlying the hematoma, water contents and glycogen levels were significantly increased at 5 and 8 hours, whereas lactate levels were increased two- to fourfold at all times. CONCLUSIONS: These results, which demonstrate normal to increased high-energy phosphate and carbohydrate substrate concentrations in edematous perihematomal regions during the early hours following ICH, are qualitatively similar to findings in other brain injury models in which a reduction in metabolic rate develops. Because an energy deficit is not present, lactate accumulation in edematous white matter is not caused by stimulated anaerobic glycolysis. Instead, because glutamate concentrations in the blood entering the brain's extracellular space during ICH are several-fold higher than normal levels, the authors speculate, on the basis of work reported by Pellerin and Magistretti, that glutamate uptake by astrocytes leads to enhanced aerobic glycolysis and lactate is generated at a rate that exceeds utilization.

Lobar intracerebral hemorrhage model in pigs: rapid edema development in perihematomal white matter.

BACKGROUND AND PURPOSE: The mechanisms underlying brain injury from intracerebral hemorrhage (ICH) are complex and poorly understood. To comprehensively examine pathophysiological and pathochemical alterations after ICH and to examine the effects of hematoma removal on these processes, we developed a physiologically controlled, reproducible, large-animal model of ICH in pigs (weight, 6 to 8 kg). METHODS: We produced lobar hematomas by pressure- controlled infusions of 1.7 mL of autologous blood into the right frontal hemispheric white matter over 15 minutes. We froze brains in situ at 1, 3, 5, and 8 hours after hematoma induction and cut coronal sections of hematoma assessment, morphological brain examination, and immunohistochemical and water content determinations. RESULTS: At 1 hour after blood infusion, "translucent" white matter areas were present directly adjacent to the hematoma. These markedly edematous regions had a greater than 10% increase in water content (>85%) compared with the contralateral white matter (73%), and this increased water content persisted through 8 hours. In addition, these areas were strongly immunoreactive for serum proteins. Intravascular Evans blue dye failed to penetrate into the brain tissue at all time points, demonstrating that this serum protein accumulation and edema development were not due to increased blood-brain barrier permeability. CONCLUSIONS: Experimental lobar ICH in pigs models a prominent pathological feature of human ICH, ie, early perihematomal edema. Our findings suggest that serum proteins, originating from the hematoma, accumulate in adjacent white matter and result in rapid and prolonged edema after ICH. This interstitial edema likely corresponds to the low densities on CT scans and the hyperintensities on T2-weighted MR images that surround intracerebral hematomas acutely after human ICH.

Use of the Morris water maze and acoustic startle chamber to evaluate neurologic injury after asphyxial arrest in rats.

The study was performed to assess the utility of the Morris water maze (MWM) and acoustic startle reflex (ASR) for evaluating neurologic outcome in a rat model of asphyxial cardiac arrest. Rats were anesthetized, intubated, and chemically paralyzed. Control animals were decannulated and, after awakening, were extubated and returned to their housing. Experimental animals were asphyxiated by disconnecting the ventilator. Approximately 3.5 min after the disconnection, there was no measurable pulse. After 7 min of asphyxia, they were then resuscitated with resumed ventilation, chest compressions, epinephrine, and sodium bicarbonate. All animals were assigned to either MWM or ASR testing. The MWM is a 6-ft diameter tank filled with opaque water. In a fixed location of the tank, a 4-inch diameter escape platform is submerged just below the surface. MWM animals were tested on post-injury d 16-21 by recording the path and time taken to escape from three randomly assigned locations per d. ASR animals had s.c. leads placed over the right triceps and tibialis anterior muscles. The latency and rectified amplitude of the ASR was measured by recording the electromyographic impulse generated when the animal was startled by an acoustic stimulus. Animals were tested on post-injury d 6 and 7. After the last test session for each group, the animals' brains were removed for histopathologic examination. Asphyxiated MWM animals took longer to find the platform, and their paths were less direct than control animals (analysis of variance p < 0.05). The ASR of asphyxiated ASR animals had greater amplitude and shorter latency compared with controls (analysis of variance p < 0.05). Histologic examination revealed no abnormalities in control animals, but 80% of asphyxiated brains showed hippocampal neuronal injury and/or reactive gliosis in the CA1 segment. Abnormalities were more commonly detected in animals killed 7 d post-injury (ASR protocol) compared with animals killed 21 d post-injury (MWM protocol). We conclude that the MWM and ASR are useful for detecting neuronal injury in asphyxiated rats.

Effect of fenbendazole molasses supplement block treatment on nematode infection and subsequent weight gain of weanling beef calves.

Two trials were conducted to evaluate the effect of fenbendazole molasses supplement block treatment on weight gain of weanling beef calves. An initial (November) oral fenbendazole (5 mg kg-1) treatment was administered to all animals in both trials. In Trials 1 and 2, respectively, two fenbendazole molasses supplement block treatments were administered 6 (6.4 mg kg-1) and 16 (7.0 mg kg-1) weeks later and 7 (3.4 mg kg-1) and 14 (3.8 mg kg-1) weeks later. During the treatment periods, calves were maintained on dormant bermuda grass pasture, supplemented with hay and protein/mineral blocks. The first block treatment was administered approximately midway through the supplement period to suppress the infection level when nutrition was marginal. The second treatment was administered just prior to ryegrass grazing. Trial 1 and 2 treatments resulted in reducing the infection level, as indicated by reduced mean fecal egg counts. Treatment group mean fecal egg counts remained lower than control group mean counts throughout each trial. In Trial 1, the treatment group gained 29.5 kg more than the control group. In Trial 2, the control group gained 15.5 kg more than the treatment group. Fecal egg count data indicated that the infection level during Trial 1 was higher than during Trial 2. This difference could influence weight gain.

Epidemiologic factors and isotype-specific antibody responses in serum and mucosal secretions of dairy calves with bovine coronavirus respiratory tract and enteric tract infections.

Blood, feces, and nasal swabs specimens were collected 12 to 24 hours after birth and then 3 times/week (blood only once per week) from one group of 10 calves until they were 10 weeks old and from a second group of 10 calves until they were 10 to 20 weeks old. Colostrum was collected from all calves' dams and tears from 5 randomly selected calves in the first group. All fecal and nasal specimens were assayed for bovine coronavirus (BCV) antigens by ELISA. Nasal epithelial cells were examined for BCV antigens by direct immunofluorescence. Isotype antibody titers to BCV in all samples from 5 calves in group 1 were evaluated by ELISA. Zinc sulfate turbidity (ZST) values were determined on the first serum samples taken from all calves in group 1. To determine whether any correlation existed between ZST values, isotype antibody titers to BCV (12 to 24 hours after birth), number of respiratory sick days, number of enteric sick days, or days to first shedding of virus, a Spearman rank order correlation coefficient was done. Bovine coronavirus respiratory tract and enteric tract infections were common on this farm. Most initial infections developed when calves were 1 to 3 weeks old; however, there were also multiple incidences of shedding of viral antigens or seroconversions at later times during the study. Persistence of infection or reinfection of the upper respiratory tract with BCV was common. Colostral antibody titers to BCV (IgG1) were in all cows at moderate amounts; however, calf serum antibody titers and ZST values (12 to 24 hours after birth) were highly variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Mucosal and systemic antibody responses to bovine coronavirus structural proteins in experimentally challenge-exposed calves fed low or high amounts of colostral antibodies.

Ten colostrum-deprived calves were assigned to 1 of 2 treatment groups (5 calves/group), and fed colostrum that had either low (naturally infected cows) or high (immunized cows) antibody titers to bovine coronavirus (BCV). All calves were inoculated orally and intranasally with virulent BCV when they were 24 to 48 hours old and challenge exposed 21 days later. Blood, feces, nasal secretions, tears, saliva, and bronchoalveolar lavage (BAL) fluids were collected weekly from each calf for 5 weeks after inoculation. The titers to whole BCV or the relative amounts of isotype-specific antibodies to BCV structural proteins were evaluated in these samples by ELISA or immunoblotting, respectively. Both pools of colostrum contained primarily IgG1, IgG2, and IgA antibodies to the E2 and E3 BCV proteins. Calves fed the high-titer colostrum had correspondingly higher amounts of passive IgG1 and IgA antibodies to whole BCV and to the E2 and E3 BCV proteins in serum, feces, and BAL fluid at postinoculation week 1 than those calves fed low-titer colostrum. Active IgG1, IgA, and IgM antibody responses in serum and active IgA and IgM antibody responses in most mucosal secretions to whole BCV and to the E2 and E3 proteins were lower or delayed in calves fed high-titer colostrum, compared with responses in calves fed low-titer colostrum. In contrast, increased responses to the BCV N protein were observed in all samples (except in serum and BAL fluid) in the calves fed high-titer colostrum, compared with calves fed low-titer colostrum. Upon challenge exposure, responses to E2 and E3 BCV proteins in serum and BAL fluid were lower in the group fed high-titer colostrum, compared with those in the group fed low-titer colostrum. Our findings indicate that the level of passive immunity in calves at the time of BCV inoculation can influence the development of active antibody responses in serum, feces, and mucosal secretions to whole BCV and to some BCV proteins individually.

Reversal sign on CT: effect of anoxic/ischemic cerebral injury in children.

A retrospective study was performed to determine the clinical and pathologic features, etiology, and outcome of children with the reversal sign. The reversal sign, a striking CT finding, probably represents a diffuse, anoxic/ischemic cerebral injury. CT features of the reversal sign are diffusely decreased density of cerebral cortical gray and white matter with a decreased or lost gray/white matter interface, or reversal of the gray/white matter densities and relatively increased density of the thalami, brainstem, and cerebellum. Twenty children with the reversal sign were retrospectively analyzed. We divided the patients into three groups: (1) acute reversal, (2) intermediate group, and (3) chronic reversal. There were nine cases of trauma (seven of child abuse); nine hypoxia/anoxia incidents (birth asphyxia, drowning, status epilepticus); one bacterial meningitis; and one degenerative encephalitis. All acute- and intermediate-group patients had respiratory problems requiring ventilator support and intensive care. In five of seven patients who died, autopsy findings were consistent with anoxic/ischemic encephalopathy. Surviving patients have profound neurologic deficits with severe developmental delay. The CT reversal sign carries a poor prognosis and indicates irreversible brain damage.

Spontaneous cerebellar hematoma associated with chronic cerebellar stimulation. Case report.

A 24-year-old man developed a spontaneous cerebellar hematoma 5 years after the implantation of cerebellar electrodes. No vascular malformations were found either intraoperatively or radiographically. The histopathological findings of the cerebellar tissue obtained at biopsy from the region surrounding the electrodes support the hypothesis of a causal relationship between the spontaneous cerebellar hemorrhage and chronic cerebellar stimulation.

Survival of pathogenic bacteria in crude oil.

The survival of three strains of Staphylococcus aureus and one strain each of Pseudomonas aeruginosa, Bacillus subtilis and Clostridium sporogenes has been investigated in samples of seven different crude oils obtained from Alberta oil fields. One strain each of Staphylococcus aureus, Pseudomonas aeruginosa, Clostridium sporogenes and Bacillus subtilis survived for longer than three years in three of the seven crude oils tested. The majority (four out of six) of the species of test micro-organisms remained viable for over two years in six out of the seven crude oils tested. Paraffinic or asphaltic-naphthenic base crude oils were better suited for the survival of the bacteria employed in these tests than were naphthenic-paraffinic or aromatic-paraffinic base oils. Only Clostridium sporogenes survived longer than three days in one of the crude oils (No. 7) which contained considerably more aromatic material than any of the other oils tested. The public health implications of the experimental results are discussed.

Clinical study of dental cements. VII. A study of bridge retainers luted with three different dental cements.

In a clinical study of three luting cements, 547 bridges and 162 crowns were permanently cemented. Patients were recalled at 6-month intervals and the restorations were examined for looseness. A pattern of retainer type, cement type and retainer success was demonstrable.