A national UK audit for diagnostic accuracy of preoperative CT chest in emergency and elective surgery during COVID-19 pandemic

AIM

To report on a snap audit of all departments in the UK as to the value of preoperative thoracic imaging, preferably computed tomography (CT), of patients undergoing any surgery to assess for changes consistent with COVID-19 preoperatively.

MATERIALS AND METHODS

All Imaging departments in the UK were contacted and asked to record the number of preoperative CT examinations performed in patients being considered for both emergency and elective surgical intervention over a 5-day period in May 2020.

RESULTS

Forty-seven percent of departments replied with data provided on >820 patients. Nineteen percent of additional preoperative CT was in patients undergoing elective intervention and 81% in patients presenting with surgical abdominal pain. There was a high rate of false positives in patients who tested negative for COVID-19, producing a sensitivity for thoracic CT of 68.4%.

CONCLUSION

This UK-wide audit demonstrates that a large number of additional thoracic imaging examinations over a 5-day period were performed with a low sensitivity for the identification of COVID-19 in this preoperative group of patients. Given these findings, it is difficult to justify this additional examination in this group of patients.

Environmental shedding of toxigenic Clostridioides difficile by asymptomatic carriers: A prospective observational study

OBJECTIVES

The aim was to compare the burden of environmental shedding of toxigenic Clostridioides difficile among asymptomatic carriers, C. difficile-infected (CDI) patients and non-carriers in an inpatient non-epidemic setting.

METHODS

C. difficile carriage was determined by positive toxin-B PCR from rectal swabs of asymptomatic patients. Active CDI was defined as a positive two-step enzyme immunoassay/polymerase chain reaction (EIA/PCR) test in patients with more than three unformed stools/24 hr. C. difficile environmental contamination was assessed by obtaining specimens from ten sites in the patients' rooms. Toxigenic strains were identified by PCR. We created a contamination scale to define the overall level of room contamination that ranged from clean to heavy contamination.

RESULTS

One hundred and seventeen rooms were screened: 70 rooms inhabited by C. difficile carriers, 30 rooms by active CDI patients and 17 rooms by non C. difficile -carriers (control). In the carrier rooms 29 (41%) had more than residual contamination, from which 17 (24%) were heavily contaminated. In the CDI rooms 12 (40%) had more than residual contamination from which three (10%) were heavily contaminated, while in the control rooms, one room (6%) had more than residual contamination and none were heavily contaminated. In a multivariate analysis, the contamination score of rooms inhabited by carriers did not differ from rooms of CDI patients, yet both were significantly more contaminated than those of non-carriers odd ratio 12.23 and 11.16 (95% confidence interval 1.5-99.96 p 0.0195, and 1.19-104.49 p 0.035), respectively.

DISCUSSION

Here we show that the rooms of C. difficile carriers are as contaminated as those of patients with active CDI and significantly more than those of non-carriers.

Molecular epidemiology of community-onset methicillin-resistant Staphylococcus aureus infections in Israel

Data on community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA) in Israel are scarce. The objective of this study was to characterize the major CA-MRSA clones in Israel. All clinical MRSA isolates detected in the community during a period of 2.5 years (2011-2013) from individuals insured by a major health maintenance organization in Israel were collected, with additional data from medical records. Antibiotic susceptibility patterns and staphylococcal chromosomal cassette mec (SCCmec) typing were determined. SCCmec IV and V isolates were further typed by pulsed-field gel electrophoresis (PFGE), spa typing, and detection of a panel of toxin genes. MRSA were detected in 280 patients, mostly from skin infections. Patients with SCCmec IV (n = 120, 43 %) were younger (p < 0.0001) and reported less contact with healthcare facilities. Almost all isolates were trimethoprim-sulfamethoxazole susceptible (98 %). spa-CC032, a typical nosocomial MRSA clone, accounted for 28 % of SCCmec IV. The two major CA-MRSA clones were t008 USA300 (13 %) and t991 (10 %); t991 was isolated mainly from children (75 %), was Panton-Valentine leukocidin (PVL) negative but eta-positive, and was typically susceptible to most antibiotic groups. PVL-positive strains (n = 31) included mainly USA300 (52 %) and t019 (13 %). While multiple genetic lineages were evident among community-onset MRSA in Israel, approximately 20 % are typical CA-MRSA clones, mainly USA300 and a local clone, t991.

The radiosensitizing effect of the aurora kinase inhibitors, ENMD-2076, on canine mast cell tumours in vitro

ENMD-2076 is an aurora kinase inhibitor that also has multi-target tyrosine kinase inhibitor properties. In this study, the mRNA and the protein expression of aurora-A and aurora-B were evaluated in three canine mast cell tumour cell lines. Dose-dependent cytotoxicity was seen in the cells treated, and it affected the cell cycle with cells in the G2/M phase being selectively killed. The cells were also evaluated for radiosensitivity with/without ENMD-2076, and radiosensitization was seen after 3 Gy and 6 Gy exposures with ENMD-2076 for 48 h. Protein expression of caspase-3 was gradually increased, and the expression intensity was highest at 24 h post irradiation in cells without ENMD-2076 treatment, which indicates that radiation exposure with ENMD-2076-induced cell death faster than radiation treatment alone. Our study results suggest the potential usefulness of treating canine mast cell tumours with aurora kinase inhibitors alone or in conjunction with radiation therapy.

Association between pubertal development and depressive symptoms in girls from a UK cohort

BACKGROUND

It is unclear whether pubertal status or timing of puberty explains the increase in depressive symptoms in girls during adolescence.

METHOD

This is a longitudinal study based on 2506 girls from the Avon Longitudinal Study of Parents and Children (ALSPAC). Self-reported depressive symptoms at 10.5, 13 and 14 years were assessed using the Short Mood and Feelings Questionnaire (SMFQ). Pubertal status (Tanner breast and pubic hair stage) and timing of menarche were derived from questionnaires administered from age 8 to 14 years. We used multivariable regression models to examine the relative contributions of pubertal status and timing in accounting for increases in level of depressive symptoms at 14 years.

RESULTS

With increasing age, the association between breast development and depressive symptoms strengthened. Pubertal status (breast stage), rather than timing of menarche, was independently associated with depressive symptoms at 14 years. There was strong evidence for a linear relationship between breast stage and depressive symptoms at 14 years [increase in 0.17 S.D. (range 0.10-0.24) of depressive symptoms for advancement of each breast stage].

CONCLUSIONS

Depressive symptoms in mid-adolescence were more strongly influenced by breast stage than timing of menarche. This could imply that the female rise in depression during adolescence is due to increasing estrogen levels, and might explain why the gender difference in rates of depression emerges at this stage. Future research should be aimed at identifying the mechanism of action of pubertal change, including direct effects of pubertal hormones and indirect effects mediated by psychosocial factors.

Onset of sexual maturity in female chickens is genetically linked to loci associated with fecundity and a sexual ornament

Onset of sexual maturation is a trait of extreme importance both evolutionarily and economically. Unsurprisingly therefore, domestication has acted to reduce the time to sexual maturation in a variety of animals, including the chicken. In comparison with wild progenitor chickens [the Red Junglefowl (RJF)], domestic layer hens attain maturity approximately 20% earlier. In addition, domestic layers also possess larger combs (a sexual ornament), produce more eggs and have denser bones. A large quantitative trait loci (QTL) analysis (n=377) was performed using an F(2) intercross between a White Leghorn layer breed and a RJF population, with onset of sexual maturity measured and mapped to three separate loci. This cross has already been analysed for comb mass, egg production and bone allocation. Onset of sexual maturity significantly correlated with comb mass, whilst the genetic architecture for sexual maturity and comb mass overlapped at all three loci. For two of these loci, the QTL for sexual maturity and comb mass were statistically indistinguishable from pleiotropy, suggesting that the alleles that increase comb mass also decrease onset of sexual maturity.

Dynamic skeletal muscle stimulation and its potential in bone adaptation

To identify mechanotransductive signals for combating musculoskeletal deterioration, it is essential to determine the components and mechanisms critical to the anabolic processes of musculoskeletal tissues. It is hypothesized that the interaction between bone and muscle may depend on fluid exchange in these tissues by mechanical loading. It has been shown that intramedullary pressure (ImP) and low-level bone strain induced by muscle stimulation (MS) has the potential to mitigate bone loss induced by disuse osteopenia. Optimized MS signals, i.e., low-intensity and high frequency, may be critical in maintaining bone mass and mitigating muscle atrophy. The objectives for this review are to discuss the potential for MS to induce ImP and strains on bone, to regulate bone adaptation, and to identify optimized stimulation frequency in the loading regimen. The potential for MS to regulate blood and fluid flow will also be discussed. The results suggest that oscillatory MS regulates fluid dynamics with minimal mechanical strain in bone. The response was shown to be dependent on loading frequency, serving as a critical mediator in mitigating bone loss. A specific regimen of dynamic MS may be optimized in vivo to attenuate disuse osteopenia and serve as a biomechanical intervention in the clinical setting.

Regulation of mechanical signals in bone

OBJECTIVES

Response of the skeleton to application and removal of specific mechanical signals is discussed. Anabolic effects of high-frequency, low-magnitude vibrations, a mechanical intervention with a favorable safety profile, as well as the modulation of bone loss by genetic and epigenetic factors during disuse are highlighted.

METHODS

Review.

RESULTS

Bone responds to a great variety of mechanical signals and both high- and low-magnitude stimuli can be sensed by the skeleton. The ability of physical signals to influence bone morphology is strongly dependent on the signal's magnitude, frequency, and duration. Loading protocols at high signal frequencies (vibrations) allow a dramatic reduction in the magnitude of the signal. In the axial skeleton, these signals can be anabolic and anti-catabolic and increase the structural strength of the tissue. They further have shown potential in maxillofacial applications to accelerate the regeneration of bone within defects. Bone's sensitivity to the application and removal of mechanical signals is heavily under the control of the genome. Bone loss modulated by the removal of weight-bearing from the skeleton is profoundly influenced by factors such as genetics, gender, and baseline morphology.

CONCLUSIONS

Adaptation of bone to functional challenges is complex but it is clear that more is not necessarily better and that even very low-magnitude mechanical signals can be anabolic. The development of effective biomechanical interventions in areas such as orthodontics, craniofacial repair, or osteoporosis will require the identification of the specific components of bone's mechanical environment that are anabolic, catabolic, or anti-catabolic.

Pleomorphic lymphoepithelioma-like carcinoma of the urinary bladder

Lymphoepithelioma-like carcinoma (LELC) of the urinary bladder is often mixed with conventional transitional cell carcinoma and/or other histotypes. The pathologist's determination of the morphologic purity of a given LELC at the biopsy stage is a clinically relevant endeavour, because there is some anecdotal evidence suggesting that pure or predominant LELC may be comparatively chemosensitive and have a favorable prognostic profile, which may potentially offer the possibility of effective therapy without bladder resection. The precise degree of cellular pleomorphism that is allowed in a pure LELC is unclear. We describe herein an otherwise conventional and pure LELC that showed, in a localized area that constituted approximately 25% of the overall tumor volume, a two to six fold variation in nuclear size, including multinucleated tumor cells. These pleomorphic areas were set in the same lymphoplasmacytic infiltrate as their conventional counterparts, and similarly displayed cellular syncytia. We performed a detailed immunophenotypic comparison between the conventional areas and the pleomorphic areas. No significant differences were found between the 2 areas in overall lymphoplasmacytic or histiocytic density, lymphocytic CD4/CD8 ratio, and lymphoplasmacytic kappa/lambda ratio. Similarly, both displayed similar qualitative and quantitative staining indices for p53, Ki67, cytokeratin AE1/AE3 and p16(INKa). Scattered cells were cytoplasmically beta-catenin positive exclusively in the pleomorphic areas; however these cells were not notably larger than the cells in the conventional areas. Both components were immunohistochemically negative for HMB-45, CD1a, the estrogen receptor, Epstein-Barr virus, CD117, D2-40, CD56, cytokeratin 20 and chromogranin. Clinicopathologic analysis of a series of cases is required to establish if there is any significance to nuclear pleomorphism in LELC. However, the phenotypic similarity between the 2 areas in this case, the intimate admixture of the pleomorphic cells with the lymphoplasmacytic infiltrate, and their syncytial pattern of growth, all suggest that pure LELC may display marked nuclear pleomorphism, and that this finding may not, in of itself, be a valid basis for removing a case from the "pure" group.

Abnormally persistent latent inhibition induced by MK801 is reversed by risperidone and by positive modulators of NMDA receptor function: differential efficacy depending on the stage of the task at which they are administered

RATIONALE

Latent inhibition (LI) is the poorer conditioning to a stimulus resulting from its nonreinforced preexposure. LI indexes the ability to ignore irrelevant stimuli and is used extensively to model attentional impairments in schizophrenia (SZ). We showed that rats and mice treated with the N-methyl-D-aspartic acid (NMDA) receptor antagonist MK801 expressed LI under conditions preventing LI expression in controls. This abnormally persistent LI was reversed by the atypical antipsychotic drug (APD) clozapine and by compounds enhancing NMDA transmission via the glycineB site, but not by the typical APD haloperidol, lending the MK801 LI model predictive validity for negative/cognitive symptoms.

OBJECTIVE

To test additional representatives from the two classes of drugs and show that the model can dissociate between atypical APDs and glycinergic drugs are the objectives of the study.

MATERIALS AND METHODS

LI was measured in a conditional emotional response procedure. Atypical APD risperidone, selective 5HT2A antagonist M100907, and three glycinergic drugs were administered in preexposure or conditioning.

RESULTS

Rats treated with MK801 (0.05 mg/kg) exhibited LI under conditions that disrupted LI in controls. This abnormality was reversed by risperidone (0.25 and 0.067 mg/kg) and M100907 (1 mg/kg) given in preexposure. Glycine (0.8 g/kg), D-cycloserine (DCS;15 and 30 mg/kg), and glycyldodecylamide (GDA; 0.05 and 0.1 g/kg.) counteracted MK801-induced LI persistence when given in conditioning.

CONCLUSIONS

These results support the validity of MK801-induced persistent LI as a model of negative/cognitive symptoms in SZ and indicate that this model may have a unique capacity to discriminate between typical APDs, atypical APDs, and glycinergic compounds, and thus, foster the identification of novel treatments for SZ.

Exposure assessment of a mercury spill in a Nevada school -- 2004

BACKGROUND

Although mercury is toxic, few studies have measured exposure in children who handled elemental mercury briefly. In 2004, a student spilled approximately 60 milliliters of mercury at a Nevada school. Within 12 hours, all students were removed from the source of exposure. We conducted an exposure assessment at the school.

METHODS

We administered questionnaires and obtained urine samples from students. Using two-sample t-tests, we compared urine mercury levels from students who self-reported exposure to mercury levels of other students.

RESULTS

Two-hundred students participated, including 55/62 (89%) who were decontaminated. The students' geometric mean urine mercury level was 0.36 microg/L (95% confidence interval 0.32-0.40 microg/L). The student who brought the mercury to school was the only one to have an elevated urine mercury level (11.4 microg/L).

CONCLUSION

Despite environmental contamination, mercury exposure may have been minimized because of rapid identification of the elemental mercury spill and decontamination.

L’imagerie par résonance magnétique cérébrale fonctionnelle en pratique clinique

In the last decade, functional MRI (fMRI) has become one of the most widely used functional imaging technique in neurosciences. However, its clinical applications remain limited. Despite methodological and practical issues, fMRI data has been validated by different techniques (magnetoencephalography, Wada test, electrical and magnetic stimulations, and surgical resections). In neurosurgical practice, fMRI can identify eloquent areas involved in motor and language functions, and may evaluate characteristics of postoperative neurological deficit including its occurrence, clinical presentation and duration. This may help to inform patients and to prepare postoperative care. fMRI may also identify epileptic foci. In neurological practice, fMRI may help to determine prognosis of recovery after stroke, appropriate medication, and rehabilitation. fMRI may help to identify patients at risk of developing Alzheimer disease. Finally, cerebrovascular reactivity imaging is an interesting approach that might provide new radiological insights of vascular function.

Topoisomerase IIalpha in Wilms' tumour: gene alterations and immunoexpression

BACKGROUND

Topoisomerase IIalpha (topoIIalpha) is an essential enzyme gene in regulating DNA structure and cell proliferation and is encoded by the TOP2A. Using cDNA microarray analysis, TOP2A has been reported to be one of the top genes overexpressed in Wilms' tumour.

AIM

To evaluate the role of TopoIIalpha in Wilms' tumorigenesis and its prognostic value.

METHODS

TOP2A gene copy numbers were determined using the fluorescence in situ hybridisation technique, and protein expression levels of TopoIIalpha by immunostaining in 39 samples of primary and 18 samples of metastatic Wilms' tumour.

RESULTS

TOP2A gene amplification was detected only in anaplastic Wilms' tumours, and none of the Wilms' tumours showed deletion of the TOP2A gene. TopoIIalpha protein overexpression was detected in 97% of Wilms' tumours, and correlated strongly with proliferation, as measured by Ki-67 (r = 0.85). The high TopoIIalpha expression was associated with the presence of vascular invasion, prominent apoptosis, metastases and adverse clinical outcomes (p<0.05).

CONCLUSIONS

Our findings suggest that TopoIIalpha overexpression in Wilms' tumours is caused by a change at the transcription level, except for anaplastic Wilms' tumours, in which gene amplification was present. High levels of TopoIIalpha protein are correlated with tumour aggressiveness. The assessment of TopoIIalpha expression in Wilms' tumour may have prognostic value.

Functional age-dependent changes in bronchoalveolar lavage rat cells

Alveolar macrophages (AM) are located at the first line of non-specific defense against inhaled antigens in the lower respiratory tract and therefore represent the major effector cell in antimicrobial defense. Since children under 2 years are known to manifest increased susceptibility to lung infections we used a rat model to study functional capacities of the AM during different stages of development We analyzed several steps of the phagocytic process (adherence, chemotaxis and ingestion) as well as two different mechanisms of cytotoxicity [antibody dependent cellular cytotoxicity (ADCC) and cytotoxicity triggered by immune complex (ICC)] and tumor necrosis factor (TNF-alpha) secretion. We used young (4-6 weeks old), intermediate (16-25 weeks old) and adult (36-45 weeks old) rats. Adherence and phagocytic capacities of AM were lower in young rats compared to intermediate and adult animals. Chemotaxis towards the C5a complement component was low in the first two months of life, then it increased in the intermediate group and fell again in adults. Bronchoalveolar lavage (BAL) cells from young rats did not produce detectable TNF-alpha levels even when stimulated with phorbol 12-myristate 13-acetate (PMA). When we studied two different cytotoxic mechanisms we found that ICC markedly declines from youth to adulthood while ADCC showed a steady increase from youth to adulthood. In conclusion, our data show differences that may help to explain in part the enhanced susceptibility to pulmonary infections found in young children.

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS)

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS) is in progress. The study design, accrual to date, and related research projects are described. Revised accrual rates and expected recruitment are given. 15 cancers have been detected to date, from a total of 1236 screening measurements. This event rate and the tumour grades reported are compared with recent reports from other studies in women at high risk of breast cancer.

Skeletal adaptation to mechanical stimuli in the absence of formation or resorption of bone

Too often, unique loading environments fail to alter bone mass and morphology, calling to question the validity of Wolff's Law; the skeleton's plasticity to mechanical signals(1). We propose that bone can accommodate new loading environments without the need to form or resorb tissue, and that a critical aspect of bone tissue's ability to adapt to mechanical stimuli is first achieved via the plasticity of the osteocyte. We suggest that the osteocyte is capable of "normalizing" its local mechanical environment by modulating its cytoskeletal architecture, attachment to the matrix, configuration of the periosteocytic space, and communication channels to surrounding cells. We believe that through this local adaptive mechanism the osteocyte can accommodate the majority of changes in the mechanical milieu without altering the tissue architecture. It is only when bone tissue is subject to more severe (albeit rare) increases or decreases in the functional environment, the osteocyte participates in the formation and/or resorption of bone by coordinating site-specific recruitment of osteoblasts and/or osteoclasts. In vivo models of bone adaptation, combined with in situ reverse transcriptase-PCR, semi-quantitative RT-PCR, Northern analysis, immuno-cytochemistry and histomorphometry, can demonstrate how distinct mechanical stimuli influence the osteocyte's cytoskeletal and lacunar architecture, coupling (and uncoupling) of the osteocyte to the matrix and neighboring cells, and the osteocyte's participation in the recruitment and differentiation of osteoblasts and osteoclasts. Thus, the osteocyte controls three strategies to modulate its local and global environment in response to three distinct functional stimuli: 1) exogenous mechanical stimuli which are distinct from normal but sufficient to maintain bone mass, 2) mechanical stimuli which are osteogenic, and 3) disuse. If it is true that the resident cell population is capable of accommodating subtle changes in the functional milieu before modification of tissue morphology is deemed necessary, a novel strategy for the development of prophylaxes for osteopenia, osseointegration and fracture healing may become apparent.

Mechanical strain, induced noninvasively in the high-frequency domain, is anabolic to cancellous bone, but not cortical bone

Departing from the premise that it is the large-amplitude signals inherent to intense functional activity that define bone morphology, we propose that it is the far lower magnitude, high-frequency mechanical signals that continually barrage the skeleton during longer term activities such as standing, which regulate skeletal architecture. To examine this hypothesis, we proposed that brief exposure to slight elevations in these endogenous mechanical signals would suffice to increase bone mass in those bones subject to the stimulus. This was tested by exposing the hind limbs of adult female sheep (n = 9) to 20 min/day of low-level (0.3g), high-frequency (30 Hz) mechanical signals, sufficient to induce a peak of approximately 5 microstrain (micro epsilon) in the tibia. Following euthanasia, peripheral quantitative computed tomography (pQCT) was used to segregate the cortical shell from the trabecular envelope of the proximal femur, revealing a 34.2% increase in bone density in the experimental animals as compared with controls (p = 0.01). Histomorphometric examination of the femur supported these density measurements, with bone volume per total volume increasing by 32% (p = 0.04). This density increase was achieved by two separate strategies: trabecular spacing decreased by 36.1% (p = 0.02), whereas trabecular number increased by 45.6% (p = 0.01), indicating the formation of cancellous bone de novo. There were no significant differences in the radii of animals subject to the stimulus, indicating that the adaptive response was local rather than systemic. The anabolic potential of the signal was evident only in trabecular bone, and there were no differences, as measured by any assay, in the cortical bone. These data suggest that subtle mechanical signals generated during predominant activities such as posture may be potent determinants of skeletal morphology. Given that these strain levels are three orders of magnitude below strains that can damage bone tissue, we believe that a noninvasive stimulus based on this sensitivity has potential for treating skeletal complications such as osteoporosis.

Breast-feeding among women exposed to polybrominated biphenyls in Michigan

In the early 1970s, the largest industrial accident in the United States resulted in widespread contamination of the food supply in Michigan with polybrominated biphenyls (PBBs). The chemical similarity of PBBs to compounds implicated as endocrine disruptors has raised the question of whether PBBs could affect the reproductive system. In the present analysis we examine the relation between serum measurements of PBBs and the frequency and duration of lactation. Persons who lived on or received food from farms exposed to PBBs were enrolled in a registry by the Michigan Department of Public Health. Female members of the cohort were invited to participate in a telephone survey of reproductive outcomes. The three outcomes of interest in the present analysis were a) the decision to breast-feed (yes/no); b) the duration, in months, of breast-feeding as the main source of nutrition; and c) the total duration, in months, of breast-feeding. None of the three outcomes was significantly associated with serum PBB levels, even after controlling for maternal age, previous history of breast-feeding, body mass index, maternal education, household income, history of smoking in the year before pregnancy, consumption of alcohol during the first trimester of pregnancy, history of thyroid disorder, gestational age of the infant in weeks, time to pregnancy, and year of birth.

Environmental public health surveillance: possible estuary-associated syndrome

Public health surveillance involves the collection, analysis, and dissemination of data for use in public health practice. A surveillance system includes the capacity to collect and analyze data as well as the ability to disseminate the data to public health agencies that can undertake effective prevention and control activities. An emerging issue in environmental public health surveillance involves human exposure to the toxins produced by microorganisms present in oceans and estuaries. One of these organisms is Pfiesteria piscicida Steidinger & Burkholder, a dinoflagellate found in estuaries along the Atlantic and gulf coasts of the United States. There have been reports of both human illness associated with occupational exposures to concentrated laboratory cultures of P. piscicida and massive fill kills associated with the presence of the organism in rivers and estuaries. These reports, and anecdotal reports from people who worked on rivers where the organism has been found, generated concern that environmental exposures to P. piscicida, similar organisms, or perhaps a toxin or toxins produced by the organism(s), could cause adverse human health effects. To begin to evaluate the public health burden associated with P. piscicida, investigators from the National Center for Environmental Health at Centers for Disease Control and Prevention and health agencies from states along the Atlantic coast collaborated to develop a passive surveillance system for collecting, classifying, and tracking public inquiries about the organism. Specifically, the group developed exposure and symptom criteria and developed data collection and reporting capabilities to capture the human health parameters collectively referred to as possible estuary-associated syndrome (PEAS). The surveillance system was implemented in six states (Delaware, Florida, Maryland, North Carolina, South Carolina, Virginia) beginning in June 1998. From 1 June 1998 through 30 June 2001, the six state health agencies participating in the PEAS surveillance system received 3,859 calls: 3,768 callers requested information and 91 callers reported symptoms. Five individuals have been identified as meeting PEAS criteria.

The anabolic activity of bone tissue, suppressed by disuse, is normalized by brief exposure to extremely low-magnitude mechanical stimuli

It is generally believed that mechanical signals must be large in order to be anabolic to bone tissue. Recent evidence indicates, however, that extremely low-magnitude (<10 microstrain) mechanical signals readily stimulate bone formation if induced at a high frequency. We examined the ability of extremely low-magnitude, high-frequency mechanical signals to restore anabolic bone cell activity inhibited by disuse. Adult female rats were randomly assigned to six groups: baseline control, age-matched control, mechanically stimulated for 10 min/day, disuse (hind limb suspension), disuse interrupted by 10 min/day of weight bearing, and disuse interrupted by 10 min/day of mechanical stimulation. After a 28 day protocol, bone formation rates (BFR) in the proximal tibia of mechanically stimulated rats increased compared with age-matched control (+97%). Disuse alone reduced BFR (-92%), a suppression only slightly curbed when disuse was interrupted by 10 min of weight bearing (-61%). In contrast, disuse interrupted by 10 min per day of low-level mechanical intervention normalized BFR to values seen in age-matched controls. This work indicates that this noninvasive, extremely low-level stimulus may provide an effective biomechanical intervention for the bone loss that plagues long-term space flight, bed rest, or immobilization caused by paralysis.

Sperm nuclear matrix association of the PRM1-->PRM2-->TNP2 domain is independent of Alu methylation

Genes or multigenic chromosomal regions are organized by the nuclear matrix into a series of functionally discrete genic domains. Biophysical analysis of the human chromosome 16p13.13 region has shown that the PRM1-->PRM2-->TNP2 protamine containing multigenic locus is bounded by two sperm nuclear matrix attachment regions (MAR). This domain exists in a transcriptionally readied or potentiated (i.e. open) chromatin state when associated with the nuclear matrix. The MAR-bounded PRM1-->PRM2-->TNP2 locus is nestled in an Alu repetitive element dense region. Fluorescence in-situ hybridization, analysis of sperm nuclear matrix/halo preparations showed that the PRM1-->PRM2-->TNP2 domain specifically localizes to the sperm nuclear matrix. This raised the question of whether nuclear matrix association and gene expression in this locus is mediated by Alu methylation. The methylation status of the various Alu elements contained within the human PRM1-->PRM2-->TNP2 locus was therefore assayed. The seven Alu elements tested, including those associated with the matrix attachment regions within the PRM1-->PRM2-->TNP2 locus, were fully methylated in sperm DNA. Conversely, these same Alu repeats were hypomethylated within the erythroleukaemic cell line, K562, which does not express any of the genes from this domain. This study shows that Alu methylation status is independent of attachment of PRM1-->PRM2-->TNP2 locus to the nuclear matrix and that Alu methylation does not play a leading role in the regulation of this domain.

Emerging areas of research reported during the CDC National Conference on Pfiesteria: from biology to public health

Since its identification in 1996, the marine dinoflagellate Pfiesteria piscicida Steidinger & Burkholder has been the focus of intense scientific inquiry in disciplines ranging from estuarine ecology to epidemiology and from molecular biology to public health. Despite these research efforts, the extent of human exposure and the degree of human illness directly associated with Pfiesteria is still in the process of being defined. Unfortunately, during this same time Pfiesteria has also stimulated media coverage that in some instances jumped ahead of the science to conclude that Pfiesteria presents a widespread threat to human health. Political and economic forces also came into play when the tourism and seafood industries were adversely impacted by rumors of toxin-laden water in estuaries along the east coast of the United States. Amid this climate of evolving science and public concern, Pfiesteria has emerged as a highly controversial public health issue. In October 2000 Centers for Disease Control and Prevention sponsored the National Conference on Pfiesteria: From Biology to Public Health to bring together Pfiesteria researchers from many disparate disciplines. The goal of this meeting was to describe the state of the science and identify directions for future research. In preparation for the conference an expert peer-review panel was commissioned to review the existing literature and identify research gaps; the summary of their review is published in this monograph. During the meeting primary Pfiesteria researchers presented previously unpublished results. The majority of those presentations are included as peer-reviewed articles in this monograph. The discussion portion of the conference focused upon researcher-identified research gaps. This article details the discussion segments of the conference and makes reference to the presentations as it describes emerging areas of Pfiesteria research.

Ultrasonic wave propagation in trabecular bone predicted by the stratified model

The objective of this study was to investigate ultrasound propagation in trabecular bone by considering the wave reflection and transmission in a multilayered medium. The use of ultrasound to identify those at risk of osteoporosis is a promising diagnostic method providing a measure of bone mineral density (BMD). A stratified model was proposed to study the effect of transmission and reflection of ultrasound wave within the trabecular architecture on the relationship between ultrasound and BMD. The results demonstrated that ultrasound velocity in trabecular bone was highly correlated with the bone apparent density (r=0.97). Moreover, a consistent pattern of the frequency dependence of ultrasound attenuation coefficient has been observed between simulation using this model and experimental measurement of trabecular bone. The normalized broadband ultrasound attenuation (nBUA) derived from the simulation results revealed that nBUA was nonlinear with respect to trabecular porosity and BMD. The curve of the relationship between nBUA and BMD was parabolic in shape, and the peak magnitude of nBUA was observed at approximately 60% of bone porosity. These results agreed with the published experimental data and demonstrated that according to the stratified model, reflection and transmission were important factors in the ultrasonic propagation through the trabecular bone.

Anabolism. Low mechanical signals strengthen long bones

Although the skeleton's adaptability to load-bearing has been recognized for over a century, the specific mechanical components responsible for strengthening it have not been identified. Here we show that after mechanically stimulating the hindlimbs of adult sheep on a daily basis for a year with 20-minute bursts of very-low-magnitude, high-frequency vibration, the density of the spongy (trabecular) bone in the proximal femur is significantly increased (by 34.2%) compared to controls. As the strain levels generated by this treatment are three orders of magnitude below those that damage bone tissue, this anabolic, non-invasive stimulus may have potential for treating skeletal conditions such as osteoporosis.

A new gadolinium-based contrast agent for magnetic resonance imaging of brain tumors: kinetic study on a C6 rat glioma model

T1-weighted magnetic resonance imaging (MRI) was used to evaluate the potential interest of a new Gd-based contrast agent, termed P760, to characterize brain tumor heterogeneity and vascularization and to delineate regions containing permeable vessels. The C6 rat glioma model was used as a model of high-grade glioblastoma. The signal enhancement was measured as a function of time in the vascular compartment and in different regions of interest (ROIs) within the tumor after the injection of 0.02 mmol x kg(-1) of P760. The results were compared to those obtained after the injection of 0.1 mmol x kg(-1) of Gd-DOTA. We showed that P760, in spite of a Gd concentration five times smaller, produces an enhancement in the blood pool similar to that produced by Gd-DOTA. It was shown that P760 makes possible an excellent delineation of regions containing vessels with a damaged blood-brain barrier (BBB). Images acquired 5-10 minutes after P760 injection showed the location of permeable vessels more accurately than Gd-DOTA-enhanced images. The enhancement produced in the tumor by P760 was, however, less than that produced by Gd-DOTA. The extravasation and/or diffusion rate of P760 in the interstitial medium were found to be strongly reduced, compared to those found with Gd-DOTA. This study suggests that the new contrast agent has promising capabilities in clinical imaging of brain tumors.

Estimated prevalence of noise-induced hearing threshold shifts among children 6 to 19 years of age: the Third National Health and Nutrition Examination Survey, 1988-1994, United States

OBJECTIVE

This analysis estimates the first nationally representative prevalence of noise-induced hearing threshold shifts (NITS) among US children. Historically, NITS has not been considered a common cause of childhood hearing problems. Among children, NITS can be a progressive problem with continued exposure to excessive noise, which can lead to high-frequency sound discrimination difficulties (eg, speech consonants and whistles).

METHODS

The Third National Health and Nutrition Examination Survey (NHANES III) was conducted from 1988 to 1994. NHANES III is a national population-based cross-sectional survey with a household interview, audiometric testing at 0.5 to 8 kHz, and compliance testing. A total of 5249 children aged 6 to 19 years completed audiometry and compliance testing for both ears in NHANES III. The criteria used to assess NITS included audiometry indicating a noise notch in at least 1 ear.

RESULTS

Of US children 6 to 19 years old, 12.5% (approximately 5.2 million) are estimated to have NITS in 1 or both ears. In the majority of the children meeting NITS criteria, only 1 ear and only 1 frequency are affected. In this analysis, all children identified with NITS passed compliance testing, which essentially rules out middle ear disorders such as conductive hearing loss. The prevalence estimate of NITS differed by sociodemographics, including age and sex.

CONCLUSIONS

These findings suggest that children are being exposed to excessive amounts of hazardous levels of noise, and children's hearing is vulnerable to these exposures. These data support the need for research on appropriate hearing conservation methods and for NITS screening programs among school-aged children. Public health interventions such as education, training, audiometric testing, exposure assessment, hearing protection, and noise control when feasible are all components of occupational hearing conservation that could be adapted to children's needs with children-specific research.

[NMR perfusion imaging: applications to the study of brain tumor angiogenesis]

NMR imaging allow specific study of contrast variations due to intravascular agents. It is possible to measure regional cerebral blood volume (rCBV). In brain tumor, this parameter allow to characterize tumoral vascularisation and blood brain barrier lesions. We use today 1st pass bolus technic. Easy to perform in clinical practice, it is useful for differential diagnosis, prebiopsic planning and follow up of lesions. That should be particularly interesting to evaluate the anti-angiogenic treatment efficiency.

The role and histological classification of needle core biopsy in comparison with fine needle aspiration cytology in the preoperative assessment of impalpable breast lesions

AIMS

To investigate the role of needle core biopsy (NCB) in the preoperative assessment of impalpable breast lesions, mainly derived from the NHS Breast Screening Programme (NHSBSP) and to assess our own modifications to a suggested system for the classification of breast NCBs.

METHODS

The NCB, fine needle aspiration cytology (FNAC), and radiology scores from 298 women with non-palpable breast lesions presenting between January 1997 and December 1998, together with the open biopsy results (where available) were collated and analysed.

RESULTS

The mean follow up period was 15.8 months (range, 5-28). The 298 NCB specimens were categorised as follows: unsatisfactory/non-representative (B1; n = 61; 20.5%), benign but uncertain whether representative (B2r; n = 52; 17.4%), benign (B2; n = 103; 34.6%), lesions possibly associated with malignancy but essentially benign (B3a; n = 9; 3.0%), atypical epithelial proliferations (B3b; n = 10; 3.4%), suspicious of malignancy (B4; n = 7; 2.3%), and malignant (B5; n = 56; 18.7%). Excision biopsy was performed in 43 cases within the B1 (n = 19), B2r (n = 8), B2 (n = 8), and the B3a (n = 8; data unavailable in one case) categories, revealing malignancy in 18 (42.8%) cases and in 65 cases within the B3b, B4, and B5 categories, revealing malignancy in 64 cases (98.5%). The sensitivity of NCB for malignancy was 87.7%, with a specificity and positive predictive value of 99.3% and 98.5%, respectively. FNAC had an inadequacy rate of 58.7%, a complete sensitivity of 34.5% and a specificity of 47.6%.

CONCLUSIONS

This study confirms the value of NCB in the preoperative assessment of impalpable breast lesions. Two new categories are suggested for the NCB classification; category B2r for benign breast tissue where representativeness is uncertain, and the subdivision of category B3 into B3a for benign lesions potentially associated with malignancy (for example, radial scars and intraduct papillomas) and B3b for more worrisome atypical epithelial proliferations. These will aid the accurate audit of NCB and identify more clearly the intellectual pathway leading to a particular assessment.

Age at menarche and tanner stage in girls exposed in utero and postnatally to polybrominated biphenyl

Accidental contamination of the Michigan food chain with polybrominated biphenyls (PBBs) led to the exposure of more than 4,000 individuals in 1973. Because PBB exposure is suspected to disrupt endocrine function, we assessed pubertal development in females 5-24 years of age (N = 327) who were exposed to PBB in utero and, in many cases, through breastfeeding. We estimated in utero PBB exposure using maternal serum PBB measurements taken after exposure (1976-1979) and extrapolated to time of pregnancy using a model of PBB decay. We found that breastfed girls exposed to high levels of PBB in utero (> or =7 parts per billion) had an earlier age at menarche (mean age = 11.6 years) than breastfed girls exposed to lower levels of PBB in utero (mean age = 12.2-12.6 years) or girls who were not breastfed (mean age = 12.7 years). This association persisted after adjustment for potential confounders (menarche ratio = 3.4, 95% confidence interval = 1.3-9.0). Perinatal PBB exposure was associated with earlier pubic hair stage in breastfed girls, but little association was found with breast development. The associations observed here lend support to the hypothesis that pubertal events may be affected by pre- and postnatal exposure to organohalogens.

Moving illusory contours activate primary visual cortex: an fMRI study

Identifying the cortical areas activated by illusory contours provides valuable information on the mechanisms of object perception. We applied functional magnetic resonance imaging to identify the visual areas of the human brain involved in the perception of a moving Kanizsa-type illusory contour. Our results indicate that, in addition to other cortical regions, areas V5 and V1 are activated. Activity in area V1 was particularly prominent.

Cloning and characterization of the murine pkd2 promoter

Pkd2, the mouse homologue of PKD2, the gene responsible for the second form of autosomal dominant polycystic kidney disease, is highly expressed in fetal and adult mouse tissues. The expression of Pkd2 is developmentally regulated. To begin to dissect out the regulatory mechanism of Pkd2 expression, we characterized the basic features of the gene structure and identified potential cis-regulatory elements of Pkd2 transcription. Pkd2 spans 42 kb with a transcription start site 165 bp upstream of the translation start codon. Exon 1 of Pkd2 is 755 bp long, and the full-length transcript is 5215 bp. The Pkd2 promoter region is GC-rich and lacks a consensus TATA or CCAAT box. Consensus binding sites for the transcription factors Sp-1, NF-1, and Ap-2 lie in the 5' upstream region of Pkd2. The Sp-1 binding site is conserved in 5' upstream sequences of both the mouse and the human genes. The CAT activity of a series of upstream segments from +178 to -2749 was assessed in MDCK, LLCPK1, COS-7, and HEK293 cells. Deletion analysis identified a 409-bp fragment from position -221 to +178 responsible for basal promoter activity. A 922-bp fragment from -744 to +178 showed the highest level of CAT activity in the cell lines tested. These data define a functional promoter candidate region for Pkd2.

Workshop to identify critical windows of exposure for children's health: reproductive health in children and adolescents work group summary

This work group report addresses the central question: What are the critical windows during development (preconception through puberty) when exposure to xenobiotics may have the greatest adverse impact on subsequent reproductive health? The reproductive system develops in stages, with sex-specific organogenesis occurring prenatally and further maturational events occurring in the perinatal period and at puberty. Complex endocrine signals as well as other regulatory factors (genetics, growth factors) are involved at all stages. Evidence from animal models and human studies indicates that many specific events can be perturbed by a variety of toxicants, with endocrine-mediated mechanisms being the more widely studied. Prioritized research needs include basic studies on the cellular-molecular and endocrine regulation of sexual differentiation and development; increased efforts regarding potential adverse effects on development in females, including breast development; expanded animal studies on different classes of chemicals, comparing responses during development (prenatal and postnatal) with responses in adults; and, more extensive explorations regarding the reproductive biology and toxicology of puberty in humans.

Determinants of polybrominated biphenyl serum decay among women in the Michigan PBB cohort

Accidental contamination of the food chain in Michigan in 1973 with polybrominated biphenyls (PBBs) led to the establishment of a registry of exposed individuals in 1976. Serum was collected and analyzed for PBB at the time of enrollment and for targeted studies in the following years. We used the archived PBB data to study the elimination of PBB and to identify factors associated with elimination. A total of 380 women >= 16 years of age who had an initial PBB level of 2 ppb and at least two serum samples drawn when they were not pregnant were included in the analysis. The mean initial PBB level was 20.9 ppb (median 4) and mean time between the first and last measurement was 4.2 years (range 0.5-11.1). PBB was assumed to reach equilibrium in the body before substantial amounts were eliminated and before the first serum measurements were taken; therefore, the entire body was modeled as a single compartment for PBB with exponential decay. Subject-specific decay rate estimates were regressed on predictor variables including initial age, body mass index (BMI), smoking history, breast-feeding duration, and parity. In women with an initial PBB level < 10 ppb, the median half-life was 12.9 years; in those with > 10 ppb, the median half-life was 28.7 years. Decay was significantly slower among women with an initial BMI at or above the median (BMI >= 23). The calculated half-life values are estimates of decay and can be used to estimate body burden of PBB at various points in time other than at the time of serum collection.

2D-spatial/2D-spectral spectroscopic imaging of intracerebral gliomas in rat brain

1H-MR spectroscopy in vivo is often hampered by poor spectral resolution. Spectral overlap can be avoided with two-dimensional spectroscopic techniques. Correlation peak imaging has been implemented to measure unambiguously the distribution of several metabolites in a rat brain glioma model. Acquisition-weighted spectroscopic imaging reduced the experimental time and provided excellent spatial localization. The choice of an appropriate spectral acquisition window granted good sensitivity. Spectroscopic images presenting a full two-dimensional spectrum in every image pixel were acquired in seven rats at 7 Tesla in 195 min, with a nominal voxel volume of 75 microl. Among other metabolites, the distribution of hypotaurine, phosphoethanolamine, alanine, and even glucose could be visualized both in the C6-glioma and in the unaffected brain.

Necrotic tumor versus brain abscess: importance of amino acids detected at 1H MR spectroscopy--initial results

PURPOSE

To assess the usefulness of the 0.9-ppm peak from amino acids (-CH3 moieties from valine, leucine, and isoleucine) for the differentiation of brain abscesses and tumors at in vivo hydrogen 1 magnetic resonance (MR) spectroscopy.

MATERIALS AND METHODS

Amino acid concentrations were determined in vitro in 13 purulent samples from brain and nonbrain tissues and in nine aseptic fluids from necrotic brain tumors at two-dimensional (2D) 1H MR spectroscopy and liquid chromatography. Thirty-four patients with cystic intracerebral mass lesions (28 tumors, six abscesses) were examined at 1H MR spectroscopy in vivo.

RESULTS

Amino acids were identified in vitro in both purulent and aseptic samples. Amino acid concentrations measured in the aseptic fluids at both liquid chromatography and 2D MR spectroscopy were far below the detection threshold of in vivo 1H MR spectroscopy. Quantitative results obtained at 2D MR spectroscopy showed no overlap in the ranges of amino acid concentrations in purulent and aseptic samples. In vivo, the proton spectra obtained with a 136-msec echo time (TE) revealed amino acids (inverted peak at 0.9 ppm) in only the abscesses.

CONCLUSION

The detection of amino acid resonance at 0.9 ppm at in vivo 1H MR spectroscopy (136-msec TE) is a promising tool for distinguishing bacterial abscesses and cystic brain tumors.

fMRI assessment of hemispheric language dominance using a simple inner speech paradigm

Hemispheric language dominance (HLD) has been determined by means of functional MRI (fMRI) using a simple, inner speech, word fluency paradigm. During the task periods, subjects perform mental imagery of visual scenes and generate silently the nouns of all objects visualized. During the control periods, subjects attend to the scanner noise. Activated areas have been identified by means of cross-correlation analysis. HLD indices have been determined by comparing the number of activated pixels detected in both hemispheres within predefined cortical areas (Brodmann areas 6, 9, 10, 39, 40 and 44-47). The paradigm has been assessed on 10 healthy, right-handed volunteers. A volume 35 mm thick, centered on the inferior frontal gyrus, was imaged. A conventional GRE MR sequence was used on a 1.5 T clinical MR scanner. HLD indices were compared with those determined for overt speech. Robust fMRI responses were obtained. HLD indices indicated left hemispheric language dominance for all subjects examined. They correlated well with those obtained for overt speech (R(2) = 0.93, regression coefficient = 0.998, with p < 10(-4)). Thus, an inner speech paradigm based on visual imagery is well adapted for assessment of HLD by means of fMRI.