Advances in Assessing Hazard and Risk to Emerging Threats and Emergency Response: Comparing and Contrasting Efforts of Three Federal Agencies

Federal statutes authorize several agencies to protect human populations from chemical emergencies and provide guidance to evacuate, clean, and re-occupy affected areas. Each of the authorized federal agencies have developed programs to provide managers, public health officials, and regulators, with a rapid assessment of potential hazards and risks associated with chemical emergencies. Emergency responses vary based on exposure scenarios, routes, temporal considerations, and the substance(s) present. Traditional chemical assessments and derivation of toxicity values are time-intensive, typically requiring large amounts of human epidemiological and experimental animal data. When a rapid assessment of health effects is needed, an integrated computational approach of augmenting extant toxicity data with in vitro (new alternative toxicity testing methods) data can provide a quick, evidence-based solution. In so doing, multiple streams of data can be used, including literature searches, hazard, dose-response, physicochemical, and environmental fate and transport property data, in vitro cell bioactivity testing and toxicogenomics. The field of toxicology is moving, ever so slowly, towards increased use of this approach as it transforms from observational to predictive science. The challenge is to objectively and transparently derive toxicity values using this approach to protect human health and the environment. Presented here are examples and efforts toward rapid risk assessment that demonstrate unified, parallel, and complementary work to provide timely protection in times of chemical emergency.

Interviewing alleged victims with mild and moderate intellectual disabilities and autism: A field study of police-investigated cases of physical and sexual abuse in a Norwegian national sample

BACKGROUND

People with intellectual disabilities (IDs) or autism are at great risk of being victims of physical and sexual abuse. This study uses transcriptions of real-life investigative interviews to examine the interview techniques (e.g. question type) used in investigative interviews of these groups of alleged victims.

METHODS

A national sample of transcribed investigative interviews (N = 96) of alleged victims with mild ID (n = 48, age 5-70 years old), moderate ID (n = 18, age 14-43 years old) and autism (n = 16, age 5-50 years old) was analysed.

RESULTS

The study shows a preponderance of alleged sexual offences (70.7%) and reveals that open-ended questions account for only 2.6% of the total number of questions asked. The interviewers relied heavily on yes/no (53.4%) and directive questions (32.2%). Suggestive questions (8.6%) were frequently used.

CONCLUSIONS

The use of question type varied considerably within and across the diagnostic group. The study reveals the need for a more in-depth analysis of variables that influence investigative interviews of people with cognitive impairments.

Tracking changes in soil organic carbon across the heterogeneous agricultural landscape of the Lower Fraser Valley of British Columbia

Increasing soil organic carbon (SOC) can improve the capacity of agricultural systems to both adapt to and mitigate climate change. Despite its importance, the current understanding of the magnitude or even the direction of SOC change in agricultural landscapes is limited. While changes in land use/land cover (LULC) and climate are among the main drivers of changes in SOC, their relative importance for the spatiotemporal assessment of SOC is unclear. This study evaluated LULC and SOC dynamics using archived and recent soil samples, remote sensing, and digital soil mapping in the Lower Fraser Valley of British Columbia, Canada. We combined both pixel- and object-based analysis of Landsat satellite imagery to assess LULC changes from 1984 to 2018. We achieved an overall accuracy of 81% and kappa coefficient of 0.77 for LULC classification using a random forest model. For predicting SOC for the same time period, we applied soil and vegetation indices derived from Landsat images, topographic indices, historic soil survey variables, and climate data in a random forest model. The SOC prediction of 2018 resulted in a coefficient of determination (R²) of 0.67, concordance correlation coefficient (CCC) of 0.76, and normalized root mean square error (nRMSE) of 0.12. For 1984, the SOC prediction accuracies were 0.46, 0.58, and 0.18 for R², CCC, and nRMSE, respectively. We detected SOC loss in 61%, gain in 12%, while 27% remained unchanged across the study area. Although we detected large losses of SOC due to LULC change, the majority of the SOC losses across the landscape were attributed to areas that were remained in the same type of agricultural production since 1984. Climate variability did not, however, have a strong effect on SOC changes. These results can inform decision making in the study area to support sustainable LULC management for enhancing SOC sequestration.

Lower expression of tumor microRNA-26a is associated with higher recurrence in patients with hepatocellular carcinoma undergoing surgical treatment

BACKGROUND AND OBJECTIVES

Hepatocellular carcinoma (HCC) in patients with hepatitis B virus (HBV) exhibit lower tumor microRNA-26a (miR-26a) expression which is associated with worse outcomes. It is unknown if similar miR-26a loss occurs in HCC developed in other liver diseases. We examined tumor miR-26a expression and its impact on recurrence and mortality in a North American HCC cohort.

METHODS

MiR-26a levels from tumor and surrounding nontumor liver tissue in 186 subjects were collected. We defined lower tumor expression of miR-26a as <1-fold that of the adjacent nontumor liver tissue.

RESULTS

Viral hepatitis (42%; 40% hepatitis C and 2% HBV), alcohol (19%), and nonalcoholic fatty liver disease (NAFLD) (18%) were the most common causes of liver disease. The prevalence of lower tumor miR-26a expression was 68%, and it was evident in HCCs arising in all etiologies (viral hepatitis 60%, alcohol 61%, and NAFLD 76%). Subjects with lower tumor miR-26a expression had significantly higher tumor recurrence (hazard ratio [HR], 2.45; 95% confidence interval [CI], 1.18 to 5.1; P = 0.016) and higher mortality of borderline significance (HR, 1.51; 95% CI, 0.94 to 2.41; P = 0.086).

CONCLUSION

Reduced miR-26a expression is a common phenomenon in HCC arising in North American patients with different underlying liver diseases and may increase recurrence and mortality after surgery.

Reactions of Three Lactones with Cl, OD, and O3: Atmospheric Impact and Trends in Furan Reactivity

Lactones, cyclic esters of hydroxycarboxylic acids, are interesting biofuel candidates as they can be made from cellulosic biomass and have favorable physical and chemical properties for distribution and use. The reactions of γ-valerolactone (GVL), γ-crotonolactone (2(5H)-F), and α-methyl-γ-crotonolactone (3M-2(5H)-F) with Cl, OD, and O₃ were investigated in a static chamber at 700 Torr and 298 ± 2 K. The relative rate method was used to determine k_GVL+Cl = (4.56 ± 0.51) × 10^-11, k_GVL+OD = (2.94 ± 0.41) × 10^-11, k_2(5H)-F+Cl = (2.94 ± 0.41) × 10^-11, k_2(5H)-F+OD = (4.06 ± 0.073) × 10^-12, k_{3M-2(5H)-F+Cl} = (16.1 ± 1.8) × 10^-11, and k_{3M-2(5H)-F+OD} = (12.6 ± 0.52) × 10^-12, all rate coefficients in units of cm³ molecule^-1 s^-1. An absolute rate method was used to determine k_2(5H)-F+O3 = (6.73 ± 0.18) × 10^-20 and k_{3M-2(5H)-F+O3} = (5.42 ± 1.23) × 10^-19 in units of cm³ molecule^-1 s^-1. Products were identified for reactions of the lactones with Cl. In the presence of O₂ the products are formic acid (HCOOH), formyl chloride (CHClO), and phosgene (CCl₂O), and also maleic anhydride (C₂H₂(CO)₂O) for 2(5H)-F. In addition both reactions produced a number of unidentified products that likely belong to molecules with the ring-structure intact. A review of literature data for reactions of other furans show that the reactivity of the lactones are generally lower compared to that of corresponding compounds without the carbonyl group.

Significance of histologic pattern of carcinoma and sarcoma components on survival outcomes of uterine carcinosarcoma

BACKGROUND

To examine the effect of the histology of carcinoma and sarcoma components on survival outcome of uterine carcinosarcoma.

PATIENTS AND METHODS

A multicenter retrospective study was conducted to examine uterine carcinosarcoma cases that underwent primary surgical staging. Archived slides were examined and histologic patterns were grouped based on carcinoma (low-grade versus high-grade) and sarcoma (homologous versus heterologous) components, correlating to clinico-pathological demographics and outcomes.

RESULTS

Among 1192 cases identified, 906 cases were evaluated for histologic patterns (carcinoma/sarcoma) with high-grade/homologous (40.8%) being the most common type followed by high-grade/heterologous (30.9%), low-grade/homologous (18.0%), and low-grade/heterologous (10.3%). On multivariate analysis, high-grade/heterologous (5-year rate, 34.0%, P = 0.024) and high-grade/homologous (45.8%, P = 0.017) but not low-grade/heterologous (50.6%, P = 0.089) were independently associated with decreased progression-free survival (PFS) compared with low-grade/homologous (60.3%). In addition, older age, residual disease at surgery, large tumor, sarcoma dominance, deep myometrial invasion, lymphovascular space invasion, and advanced-stage disease were independently associated with decreased PFS (all, P < 0.01). Both postoperative chemotherapy (5-year rates, 48.6% versus 39.0%, P < 0.001) and radiotherapy (50.1% versus 44.1%, P = 0.007) were significantly associated with improved PFS in univariate analysis. However, on multivariate analysis, only postoperative chemotherapy remained an independent predictor for improved PFS [hazard ratio (HR) 0.34, 95% confidence interval (CI) 0.27-0.43, P < 0.001]. On univariate analysis, significant treatment benefits for PFS were seen with ifosfamide for low-grade carcinoma (82.0% versus 49.8%, P = 0.001), platinum for high-grade carcinoma (46.9% versus 32.4%, P = 0.034) and homologous sarcoma (53.1% versus 38.2%, P = 0.017), and anthracycline for heterologous sarcoma (66.2% versus 39.3%, P = 0.005). Conversely, platinum, taxane, and anthracycline for low-grade carcinoma, and anthracycline for homologous sarcoma had no effect on PFS compared with non-chemotherapy group (all, P > 0.05). On multivariate analysis, ifosfamide for low-grade/homologous (HR 0.21, 95% CI 0.07-0.63, P = 0.005), platinum for high-grade/homologous (HR 0.36, 95% CI 0.22-0.60, P < 0.001), and anthracycline for high-grade/heterologous (HR 0.30, 95% CI 0.14-0.62, P = 0.001) remained independent predictors for improved PFS. Analyses of 1096 metastatic sites showed that carcinoma components tended to spread lymphatically, while sarcoma components tended to spread loco-regionally (P < 0.001).

CONCLUSION

Characterization of histologic pattern provides valuable information in the management of uterine carcinosarcoma.

Activating ERBB4 mutations in non-small cell lung cancer

Recent efforts to comprehensively characterize the mutational landscape of non-small cell lung cancer have identified frequent mutations in the receptor tyrosine kinase ERBB4. However, the significance of mutated ERBB4 in non-small cell lung cancer remains elusive. Here, we have functionally characterized nine ERBB4 mutations previously identified in lung adenocarcinoma. Four out of the nine mutations, Y285C, D595V, D931Y and K935I, were found to be activating, increasing both basal and ligand-induced ErbB4 phosphorylation. According to structural analysis, the four activating mutations were located at critical positions at the dimerization interfaces of the ErbB4 extracellular (Y285C and D595V) and kinase (D931Y and K935I) domains. Consistently, the mutations enhanced ErbB4 dimerization and increased the trans activation in ErbB4 homodimers and ErbB4-ErbB2 heterodimers. The expression of the activating ERBB4 mutants promoted survival of NIH 3T3 cells in the absence of serum. Interestingly, serum starvation of NIH 3T3 cells expressing the ERBB4 mutants only moderately increased the phosphorylation of canonical ErbB signaling pathway effectors Erk1/2 and Akt as compared with wild-type ERBB4. In contrast, the mutations clearly enhanced the proteolytic release of signaling-competent ErbB4 intracellular domain. These results suggest the presence of activating driver mutations of ERBB4 in non-small cell lung cancer.

Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana

Hotter conditions favour effectively unbanded (EUB) shells in the snail Theba pisana. T. pisana is also polymorphic for colour of the shell's apex, determined by a pair of alleles at a locus linked to the banding locus. Apex colour is epistatic to shell banding, such that banded snails with a dark apex have darker bands. Annual censuses over 22 years across an ecotone between a sheltered Acacia thicket and open dune vegetation showed a persistent association of both EUB shells and pale apex with the Open habitat. The parallel variation was due partly to strong phenotypic disequilibrium, as the combination of EUB with dark apex was rare. Nevertheless, in fully banded shells the frequency of pale apex was also higher in the Open habitat, confirming independent, parallel associations of the two contributors to paleness. Within the Acacia habitat, temporal variation of the frequencies of banding morphs was much greater than for apex colour, and EUB shells were associated with hotter summers. Consistent with its primary effect only on the very small snails, apex colour did not vary with summer conditions, but instead, higher frequencies of pale apices were associated with sunnier winters. The intensity of selection was lower on apex colour than shell banding, due partly to the constraint of phenotypic disequilibrium. The shell traits in T. pisana are an example of complex responses to climatic variation, in which phenotypic disequilibrium constrains evolution of apex colour, but separate mechanisms of selection are evident.

Involvement of the first transmembrane segment of human α(2) -adrenoceptors in the subtype-selective binding of chlorpromazine, spiperone and spiroxatrine

BACKGROUND AND PURPOSE

Some large antagonist ligands (ARC239, chlorpromazine, prazosin, spiperone, spiroxatrine) bind to the human α(2A) -adrenoceptor with 10- to 100-fold lower affinity than to the α(2B)- and α(2C)-adrenoceptor subtypes. Previous mutagenesis studies have not explained this subtype selectivity.

EXPERIMENTAL APPROACH

The possible involvement of the extracellular amino terminus and transmembrane domain 1 (TM1) in subtype selectivity was elucidated with eight chimaeric receptors: six where TM1 and the N-terminus were exchanged between the α(2)-adrenoceptor subtypes and two where only TM1 was exchanged. Receptors were expressed in CHO cells and tested for ligand binding with nine chemically diverse antagonist ligands. For purposes of interpretation, molecular models of the three human α(2)-adrenoceptors were constructed based on the β(2)-adrenoceptor crystal structure.

KEY RESULTS

The affinities of three antagonists (spiperone, spiroxatrine and chlorpromazine) were significantly improved by TM1 substitutions of the α(2A)-adrenoceptor, but reciprocal effects were not seen for chimaeric receptors based on α(2B)- and α(2C)-adrenoceptors. Molecular docking of these ligands suggested that binding occurs in the orthosteric ligand binding pocket.

CONCLUSIONS AND IMPLICATIONS

TM1 is involved in determining the low affinity of some antagonist ligands at the human α(2A)-adrenoceptor. The exact mechanism is not known, but the position of TM1 at a large distance from the binding pocket indicates that TM1 does not participate in specific side-chain interactions with amino acids within the binding pocket of the receptor or with ligands bound therein. Instead, molecular models suggest that TM1 has indirect conformational effects related to the charge distribution or overall shape of the binding pocket.

COMPARATIVE VIRULENCE OF ST. LOUIS ENCEPHALITIS VIRUS CULTURED WITH BRAIN TISSUE FROM INNATELY SUSCEPTIBLE AND INNATELY RESISTANT MICE

We find that St. Louis encephalitis virus cultured in 10 per cent serum-Tyrode solution plus brain tissue from 1-day-old innately susceptible mice attains a higher titre than when cultured in a similar solution plus brain tissue from 1-day-old closely related, yet innately resistant mice. This difference in titre persists regardless of whether the serum comes from innately susceptible or resistant mice. The relatively high titre of virus in the susceptible media is not affected by the addition of an extract (not cell-free) from the resistant brain; the relatively low titre of the virus in the resistant media may possibly be slightly enhanced by the addition of an extract from the susceptible brain. The findings as a whole show that the marked difference in the increase of St. Louis encephalitis virus in the brain tissue of innately susceptible and resistant mice, on culture in vitro, is due to some difference in the brain tissue itself.

Survival of a cat with pneumonia due to cowpox virus and feline herpesvirus infection

Cowpox virus infection in cats is rare and usually leads to cutaneous lesions alone. Pulmonary infection and pneumonia have been documented occasionally but all such cases described to date have been fatal. Although usually affecting the upper respiratory tract, feline herpesvirus can also induce pneumonia. The present report describes the case of a cat that recovered from a pneumonia in which both poxvirus and feline herpesvirus were demonstrated.

Isotope-specific detection of low-density materials with laser-based monoenergetic gamma-rays

What we believe to be the first demonstration of isotope-specific detection of a low-Z and low density object shielded by a high-Z and high-density material using monoenergetic gamma rays is reported. The isotope-specific detection of LiH shielded by Pb and Al is accomplished using the nuclear resonance fluorescence line of L7i at 478 keV. Resonant photons are produced via laser-based Compton scattering. The detection techniques are general, and the confidence level obtained is shown to be superior to that yielded by conventional x-ray and gamma-ray techniques in these situations.

Validation of quantitative magnetic resonance (QMR) for determination of body composition in rats

OBJECTIVE: To validate the use of quantitative magnetic resonance (QMR) to measure fat and lean mass in conscious rats. METHODS: Fifty Osborne-Mendel rats (249-770 g) were scanned using the Echo Medical 2 MHz body composition analyzer. Each rat was scanned under six settings (three acquisition times, with and without determination of total water). Precision was determined by the calculated coefficient of variation (CV) of three consecutive scans. Accuracy was determined by comparing the first scan to chemical carcass analysis and analyzed by paired t-tests and least-squares regression analyses. Twenty-five rats were used in the validation study, and 25 in the cross-validation study. RESULTS: The precision for fat, lean and water at all settings was <1%. QMR significantly overestimated fat (~5%; P<0.0001), and underestimated both lean (~12.5%; P<0.0001) and total water (~5.5%; P<0.0001). All QMR measures were significantly correlated with carcass measures (r(2)>0.99; P<0.0001). Using prediction equations from the validation study with the cross-validation rats, there were no significant differences between QMR fat and carcass fat at any setting (P>0.400). For four of the six QMR settings, there were no significant differences between QMR and carcass lean (P>0.05). For total water, all QMR settings were significantly different than carcass (P<0.05), but only by ~1%. CONCLUSIONS: QMR showed excellent precision for the determination of fat, lean and water. Despite overestimating fat and underestimating lean and water, all were highly related to carcass values. When tested in the cross-validation group, QMR fat could be accurately predicted at all settings; however, lean mass (two settings) and water were still slightly different (less than 1%).

Genetic structure of Melanotaenia australis at local and regional scales in the east Kimberley, Western Australia

The Kimberley region of Western Australia possesses a poorly studied freshwater fish fauna with high endemism in an aquatic landscape subject to monsoonal floods and dry season isolation. In the first population genetic study of freshwater fish in this region, the authors tested the effects of geographic barriers on genetic structure at multiple spatial scales in east Kimberley populations of the western rainbowfish, Melanotaenia australis, the most widespread and abundant species in the region. Based on allozyme comparisons, hierarchical analysis of F(ST) revealed increasing genetic subdivision with spatial scale. Minimal genetic structure within creeklines demonstrated that wet season dispersal, rather than dry season isolation, determines genetic structure at small scales. At the scale of sub-catchments, a pattern of isolation by distance along creeklines was evident. Genetic subdivision between adjacent river systems was greater between rivers separated by a plateau than by lowlands. This implies greater connectivity of populations in lowland areas and may explain the greater similarity of the east Kimberly freshwater fish fauna with lowlands to the east than with the more rugged regions to the west. Similarly, greater connectivity between lowland populations may account for the on-average larger distribution of lowland Melanotaeniids.

Validation of quantitative magnetic resonance for the determination of body composition of mice

OBJECTIVE: The aim of this study was to assess the precision and accuracy of a quantitative magnetic resonance (QMR) instrument for measuring body composition in live, non-anesthetized mice. METHODS: Forty-eight mice of varying strains, ages and body weights (15.3 to 50.2g) were scanned three times each in the QMR instrument. Animals were killed and chemical carcass analysis performed for comparison. Precision was assessed as the coefficient of variation (CV) for the triplicate scans and accuracy was determined by comparing the first QMR data with the chemical analysis. Prediction equations were generated by linear regression analysis and used in a cross-validation study in which 26 mice were scanned once each, killed, and chemical carcass analysis performed. RESULTS: The mean CV was 1.58% for fat mass (FM) and 0.78% for lean-tissue mass (LTM). QMR significantly (P<0.01) overestimated FM (7.76±5.93 vs. 6.03±5.17g) and underestimated LTM (20.73±6.19 vs. 22.48±6.75g) when compared with chemical carcass analysis. A strong relationship between QMR and chemical data (r(2)=0.99 and r(2)=0.97 for fat and LTM respectively; P<0.0001) allowed for the generation of correction equations that were applied to QMR data in the cross-validation study. There was no significant difference between data predicted from QMR and chemical carcass data for FM and LTM (P=0.15 and 0.10 respectively). CONCLUSION: The QMR instrument showed excellent precision and data was highly correlated with chemical carcass analysis. This combined with QMR's speed for whole animal analysis (95 seconds) make it a highly feasible and useful method for the determination of body composition in live, non-anesthetized mice.

Characterization of microsatellite loci for the littorine snail Bembicium vittatum

We describe the isolation and development of 17 polymorphic microsatellite loci for the intertidal snail Bembicium vittatum (Gastropoda: Littorinidae). The loci were tested in 46 individuals from a single population situated near the centre of the species distribution. No evidence of linkage disequilibrium was detected between any pair of loci. However, two loci showed significant departures from Hardy-Weinberg expectations. The number of alleles per locus ranged from two to 15.

Adaptive responses of independent traits to the same environmental gradient in the intertidal snail Bembicium vittatum

The snail Bembicium vittatum occupies a wide range of intertidal habitats in the Houtman Abrolhos Islands, Western Australia. Allozyme variation reflects patterns of connectivity, which are independent of local habitat. In contrast, heritable differences in shell shape among 83 shore sites vary with habitat, indicating local adaptation. Here we examine dimorphisms of colour and spotting of the shell in the same populations, as a test of consistency and complexity of patterns of local adaptation. Within populations, the frequency of spotted shells is higher in dark shells. Despite this association, spatial variations of colour and spotting are only weakly correlated. As predicted for traits associated with local adaptation, subdivision is greater for colour, spotting and shape than for allozymes. Colour and shape are associated with local habitat, such that populations on vertical shores have higher frequencies of dark and relatively flatter shells than those on gently sloping shores. These associations are repeatable between three separate groups of islands. Spotting shows a weaker, but significant association with the same gradient. Although shape does not differ between colour morphs within populations, the proportion of dark shells is strongly associated with shape. Thus, the independent shell traits are apparently adapted to a common, biologically significant gradient, even though the adaptive mechanisms probably differ for colour and shape. The parallel variations of independent traits highlight both the complexity of local adaptation and the potential to reveal evolutionarily significant environmental contrasts by examining adaptively relevant traits.

The second extracellular loop of alpha2A-adrenoceptors contributes to the binding of yohimbine analogues

BACKGROUND AND PURPOSE

Rodent alpha(2A)-adrenoceptors bind the classical alpha(2)-antagonists yohimbine and rauwolscine with lower affinity than the human alpha(2A)-adrenoceptor. A serine-cysteine difference in the fifth transmembrane helix (TM; position 5.43) partially explains this, but all determinants of the interspecies binding selectivity are not known. Molecular models of alpha(2A)-adrenoceptors suggest that the second extracellular loop (XL2) folds above the binding cavity and may participate in antagonist binding.

EXPERIMENTAL APPROACH

Amino acids facing the binding cavity were identified using molecular models: side chains of residues 5.43 in TM5 and xl2.49 and xl2.51 in XL2 differ between the mouse and human receptors. Reciprocal mutations were made in mouse and human alpha(2A)-adrenoceptors at positions 5.43, xl2.49 and xl2.51, and tested with a set of thirteen chemically diverse ligands in competition binding assays.

KEY RESULTS

Reciprocal effects on the binding of yohimbine and rauwolscine in human and mouse alpha(2A)-adrenoceptors were observed for mutations at 5.43, xl2.49 and xl2.51. The binding profile of RS-79948-197 was reversed only by the XL2 substitutions.

CONCLUSIONS AND IMPLICATIONS

Positions 5.43, xl2.49 and xl2.51 are major determinants of the species preference for yohimbine and rauwolscine of the human versus mouse alpha(2A)-adrenoceptors. Residues at positions xl2.49 and xl2.51 determine the binding preference of RS-79948-197 for the human alpha(2A)-adrenoceptor. Thus, XL2 is involved in determining the species preferences of alpha(2A)-adrenoceptors of human and mouse for some antagonists.

Cryptic speciation in two widespread subterranean amphipod genera reflects historical drainage patterns in an ancient landscape

The landscape of the Pilbara region of Western Australia has been relatively unchanged for 100 million years. The ancient river systems of this region might be expected to be sources of isolation and divergence for aquatic species. Hence, the occurrence of widespread groundwater taxa in this landscape offers the opportunity to examine associations between genetic diversity and drainage patterns. Pilbarus and Chydaekata are two widespread genera of subterranean amphipods endemic to the Pilbara, each occupying multiple tributaries. We used molecular data to examine the roles of drainage patterns in structuring genetic diversity. Gene flow within a tributary may be facilitated by the occasional occurrence of these amphipods in springs, which results in their downstream dispersal during episodic flooding. However, tributary boundaries may form hydrological barriers to gene flow, resulting in localised isolation of populations and divergence. Samples of both genera, collected throughout three river basins, were examined for sequence divergence in the cytochrome c oxidase I mitochondrial gene. There was no evidence of contemporary gene flow among populations of either genus, and each tributary contained highly divergent lineages, which were not associated with similar morphological differentiation. This suggests cryptic speciation has occurred, and similar phylogenetic signals in both taxa imply similar evolutionary histories. Surface populations may have been driven into subterranean refugia by the cessation of flow in the rivers, associated with Tertiary climate change, while morphological evolution may have been constrained by stabilising selection. The lack of congruence between molecular diversity and morphology raises important practical issues for conservation.

Results of pacemaker implantation in 104 dogs

OBJECTIVES

To document the outcome, survival and complications involved in pacemaker implantation in dogs in a retrospective study.

METHODS

Case records for all dogs in which pacemaker implantation was performed were reviewed.

RESULTS

A total of 104 dogs underwent pacemaker implantation. Dogs were presented with atrioventricular (AV) block (71), sick sinus syndrome (25) or vasovagal syncope (eight). Age at presentation varied from six months to 13 years with a median age of seven years and two months. The Labrador was the most commonly represented breed (17 cases). All but one dog survived pacemaker implantation, with 93 showing resolution of their clinical signs while 10 dogs showed intermittent residual signs. One-, three- and five-year survival estimates were 86, 65 and 39 per cent, respectively. Major complications after implantation were documented in 15 dogs and three of these led to fatalities. Minor complications were noted in 23 dogs. Sudden death occurred in six dogs three to 55 months following successful pacemaker implantation.

CLINICAL SIGNIFICANCE

Transvenous pacemaker implantation was successful in reducing or eliminating clinical signs in over 90 per cent of dogs with third-degree atrioventricular (AV) block or sick sinus syndrome. In dogs with vasovagal syncope, six of eight dogs had greatly reduced frequency of collapse and two became asymptomatic. Although the procedure was associated with complications, these were rarely life threatening and good survival was documented in the majority of cases.

Successful medical treatment of 15 dogs with pyothorax

OBJECTIVES

To review the success of non-surgical management, which included antibiotics and a single thoracocentesis, in 15 dogs presenting with pyothorax.

METHODS

Sixteen dogs were selected retrospectively from case files at the Veterinary Cardiorespiratory Centre.

RESULTS

One dog was diagnosed with a mass suspected to be a pulmonary abscess on ultrasound examination and was referred for surgery. Fifteen dogs were treated medically. Springer spaniels were the most commonly presented breed (six cases) followed by Labrador retrievers (three cases). Under sedation or general anaesthesia, thoracocentesis was performed unilaterally and as much purulent effusion as possible was removed. Lavage of the thorax was not undertaken. In most dogs, antibiotic treatment was ampicillin at a mean dose of 33 mg/kg administered three times daily and 25 mg/kg metronidazole administered twice daily. Antibiotics were provided for a minimum of six weeks. All dogs recovered completely and did not show relapse on prolonged follow-up. This included one dog, which had very widespread pleural adhesions and minimal effusion.

CLINICAL SIGNIFICANCE

In dogs that do not have evidence of pulmonary masses or consolidations and no evidence of granular pleural effusion, medical therapy may be curative even in chronic cases of pyothorax with pleural adhesions.

Neurotrophic modulation of myelinated cutaneous innervation and mechanical sensory loss in diabetic mice

Human diabetic patients often lose touch and vibratory sensations, but to date, most studies on diabetes-induced sensory nerve degeneration have focused on epidermal C-fibers. Here, we explored the effects of diabetes on cutaneous myelinated fibers in relation to the behavioral responses to tactile stimuli from diabetic mice. Weekly behavioral testing began prior to streptozotocin (STZ) administration and continued until 8 weeks, at which time myelinated fiber innervation was examined in the footpad by immunohistochemistry using antiserum to neurofilament heavy chain (NF-H) and myelin basic protein (MBP). Diabetic mice developed reduced behavioral responses to non-noxious (monofilaments) and noxious (pinprick) stimuli. In addition, diabetic mice displayed a 50% reduction in NF-H-positive myelinated innervation of the dermal footpad compared with non-diabetic mice. To test whether two neurotrophins nerve growth factor (NGF) and/or neurotrophin-3 (NT-3) known to support myelinated cutaneous fibers could influence myelinated innervation, diabetic mice were treated intrathecally for 2 weeks with NGF, NT-3, NGF and NT-3. Neurotrophin-treated mice were then compared with diabetic mice treated with insulin for 2 weeks. NGF and insulin treatment both increased paw withdrawal to mechanical stimulation in diabetic mice, whereas NT-3 or a combination of NGF and NT-3 failed to alter paw withdrawal responses. Surprisingly, all treatments significantly increased myelinated innervation compared with control-treated diabetic mice, demonstrating that myelinated cutaneous fibers damaged by hyperglycemia respond to intrathecal administration of neurotrophins. Moreover, NT-3 treatment increased epidermal Merkel cell numbers associated with nerve fibers, consistent with increased numbers of NT-3-responsive slowly adapting A-fibers. These studies suggest that myelinated fiber loss may contribute as significantly as unmyelinated epidermal loss in diabetic neuropathy, and the contradiction between neurotrophin-induced increases in dermal innervation and behavior emphasizes the need for multiple approaches to accurately assess sensory improvements in diabetic neuropathy.

Characterization of novel splice variants of the PAC1 receptor in human neuroblastoma cells: consequences for signaling by VIP and PACAP

Expression of VPAC and PAC1 receptor isoforms was determined in six neuroblastoma cell lines as well as in human embryonic and adult brain using reverse transcriptase PCR and quantitative PCR. PAC1 receptor splice variants missing a 21 amino acid sequence in the amino terminal domain were found to be the major receptor variants in the neuroblastoma cell lines and also were highly expressed in embryonic brain compared to adult brain. In four of the neuroblastoma cell lines, VIP and PACAP stimulated cyclic AMP production with different potencies and levels of maximal stimulation. High potency and greatest maximal stimulation of cyclic AMP for each peptide were recorded in SH-SY5Y cells, indicating the presence of high affinity VIP and PACAP receptors. Further characterization of specific VPAC and PAC1 receptor isoforms was carried out in the SH-SY5Y cell line, where along with known PAC1 receptor splice variants and the VPAC2 receptor, a number of novel PAC1 receptor splice variants were identified. The comparatively low level expression of the VPAC2 receptor along with the poor responsiveness of SH-SY5Y cells to the VPAC2 receptor-specific agonist Ro 25-1553 indicated that this receptor did not contribute significantly to the observed VIP responses. When the individual PAC1 receptor isoforms were expressed in COS 7 cells, the ability of VIP to activate cyclic AMP production was increased more than 50-fold at the majority of the PAC1 receptor variants lacking the 21 amino acid amino terminal domain sequence compared to those with the complete domain. Smaller changes were seen in the potency of PACAP-38. Similar trends were seen with inositol phosphate responses, where in each case agonist potencies were lower than for cyclic AMP production. The results of this study show that the combination of different amino terminal and intracellular loop 3 splicing variants in the PAC1 receptor dictates the ability of agonists, particularly VIP, to activate signaling pathways. VIP has considerably greater potency at most PAC1 receptors with the short amino terminal domain, and these therefore may mediate physiological effects of both VIP and PACAP. Furthermore, there may be a phenotypic switch in the expression of different PAC1 receptor amino terminal splice variants between embryonic and mature nervous system, indicating that regulation of this event may have an important role in VIP/PACAP function, particularly in the developing nervous system.

Estrogen increases sensory nociceptor neuritogenesis in vitro by a direct, nerve growth factor-independent mechanism

Estrogen affects many aspects of the nervous system, including pain sensitivity and neural regulation of vascular function. We have shown that estrogen elevation increases sensory nociceptor innervation of arterioles in Sprague-Dawley rat mammary gland, external ear and mesentery, suggesting widespread effects on sensory vasodilatory innervation. However, it is unclear whether estrogen elicits nociceptor hyperinnervation by promoting target release of neurotrophic factors, or by direct effects on sensory neurons. To determine if estrogen may promote axon sprouting by increasing release of target-derived diffusible factors, dorsal root ganglia explants were co-cultured with mesenteric arterioles for 36 h in the absence or presence of 17beta-estradiol (E2). Mesenteric arteriolar target substantially increased neurite outgrowth from explanted ganglia, but estrogen had no effect on outgrowth, suggesting that estrogen does not increase the availability of trophic proteins responsible for target-induced neurite outgrowth. To assess the direct effects of estrogen, dissociated neonatal dorsal root ganglion neurons were cultured for 3 days in the absence or presence of E2 and nerve growth factor (NGF; 1-10 ng/mL), and immunostained for the nociceptor markers peripherin or calcitonin gene-related peptide. NGF increased neuron size, survival and numbers of neurons with neurites, but did not affect neurite area per neuron. Estrogen did not affect neuron survival, size or numbers of neurons with neurites, but did increase neurite area per neuron. The effects of these agents were not synergistic. We conclude that estrogen exerts direct effects on nociceptor neurons to promote axon outgrowth, and this occurs through an NGF-independent mechanism.

Comparison of software versions for body composition analysis using the PIXImus dual-energy X-ray absorptiometer

We have previously validated the use of dual-energy X-ray absorptiometry (DXA) for measuring body composition of mice using the GE-Lunar PIXImus and software version 1.42 [1]. Since that report, newer versions of the software have been released. The purpose of the present study was to compare results from our original study with results analyzed using two newer versions of software (versions 1.44 and 1.45). Body composition data (lean tissue mass [LTM], fat mass [FM], bone mineral content [BMC], and bone mineral density [BMD]) were obtained from DXA scans of twenty-five, anesthetized male C57Bl/6J mice (6-11 weeks old; 19 to 29g). Relative to version 1.42, versions 1.44 and 1.45 significantly (P<0.001) overestimated LTM and BMD and underestimated FM and BMC. However, compared to carcass analysis, versions 1.44 and 1.45 significantly overestimated both FM and LTM and underestimated BMC. Results from 1.44 and 1.45 were highly correlated with carcass values for all body composition parameters. Prediction equations were developed for the two new software versions. Applying the prediction equation from 1.42, to the data obtained from 1.44 and 1.45 resulted in FM and LTM that were worse than if no equation was used. However, using their own developed equations resulted in data that were not significantly different than that from carcass analysis. These data suggest that software-specific equations are necessary for comparing DXA-derived data to that of chemical analysis.

Toxicologic and histopathologic response of the terrestrial salamander Plethodon cinereus to soil exposures of 1,3,5-trinitrohexahydro-1,3,5-triazine

Red-backed salamanders (Plethodon cinereus) were exposed to four different concentrations of 1,3,5-trinitrohexahydro-1,3,5-triazine (RDX) in soil under controlled laboratory conditions for 28 days. Wild-caught P. cinereus (N = 20/treatment) were exposed to target concentrations of 5,000, 1000, 100, 10, and 0 mg RDX/kg soil (dry wt) using a microcosm design. Animals were fed 5 to 10 uncontaminated mutant Drosophila flies every 3 days and monitored daily. Animals were weighed 1 day before being placed in treatment and weekly thereafter. RDX concentrations in soil were analytically determined after the compound was added and mixed at the beginning, the midpoint, and the end of exposure. RDX soil concentrations were relatively stable throughout the exposure period. Signs of overt toxicity were observed primarily in the highest exposure group. Salamanders exposed to 5,000 mg RDX/kg soil exhibited signs of neuromuscular effects (lethargy, gaping, hypersensitivity, tremors) and exhibited significant weight loss. A single moribund animal from this group lost >20% of its original body weight and was killed. Animals in this exposure group also lost weight relative to animals in other treatments. Histopathologic evaluations, including an evaluation of melanomacrophage parameters, indicated no strong treatment-related findings. This study provided information regarding the effects from subchronic dermal exposure of a terrestrial amphibian species to RDX in soil and provides a microcosm approach to the evaluation of toxicity of contaminants in soil to a terrestrial vertebrate.

Identification and characterization of a novel luciferase-like protein in the human female reproductive tract

A novel cDNA was cloned from human endometrium, matching a human gene with the interim name KIAA1463. An mRNA identified by 5'-rapid amplification of cDNA ends was found to be 3349 nt in length. PCR analysis also identified another transcript of 6626 nt, with an open reading frame encoding a 900 amino acid protein. A fold recognition program identified similarity to firefly luciferase containing an AMP-binding motif; hence, we refer to the predicted protein as the AMP binding/luciferase-like protein (ALLP). ALLP mRNA and protein were expressed throughout the female reproductive tract with the highest levels found in the ovary and uterus. In situ hybridization and immunohistochemistry showed predominant localization of the ALLP mRNA/protein in endometrial glandular epithelium and within the theca and granulosa cells in the ovary. In the endometrium expression of ALLP, mRNA and protein were higher during d 16-21 of the secretory phase of the cycle. Western blot analysis showed decreased expression of ALLP in the postmenopausal endometrium, and hormone replacement therapy increased the expression of ALLP. Endometrial adenocarcinoma cell lines expressed more ALLP, compared with cultured primary endometrial cells or normal endometrial tissue. The ubiquitous expression of ALLP in reproductive and nonreproductive tissues suggests that this protein, which is probably regulated by ovarian steroids, plays an important metabolic role and may be involved in such processes as implantation and tumorigenesis.

Seasonal variations in activity concentrations of 99Tc and 137Cs in the edible meat fraction of crabs and lobsters from the central Irish Sea

Discharges of most radionuclides into the Irish Sea from the BNFL site at Sellafield have decreased over the past 20 years or so. For a few radionuclides, however, discharges have peaked more recently. Notably, operation of the Enhanced Actinide Removal Plant (EARP) since 1994 has led to an increase in discharges of (99)Tc, as a result of the treatment of previously stored waste, with consequent increases in (99)Tc activity concentrations in a number of marine species, particularly in crustaceans such as lobsters. Previous research has considered the significance of factors such as sex and body weight on radionuclide concentrations. The current project set out to investigate whether seasonal variations in radionuclide concentrations in crabs and lobsters occur, with particular emphasis on the dynamics of (99)Tc and (137)Cs. Organisms were obtained from a site off the Isle of Man, where radionuclide concentrations were measurable but the site was sufficiently distant from Sellafield that the radionuclides were well mixed in the water column and not likely to be influenced by the pulsed nature of discharges of (99)Tc. Crab and lobster samples were collected monthly, between February 2000 and February 2001. Fifteen or 16 individuals (evenly split as male and female) of each species were collected on each occasion. Seawater samples were also collected over the 12-month period. Activity concentrations of (99)Tc in the edible meat fraction (both brown and white meat) ranged from 0.23 to 2.46 Bq kg(-1) (fresh weight (fw)) in crabs and 124 to 216 Bq kg(-1) (fw) in lobsters, with no observed seasonal variations. Activity concentrations of (137)Cs in both crab and lobster were lower, ranging from <0.16 to 0.85 Bq kg(-1) for crab meat (fw) and <0.3 to 3.3 Bq kg(-1) for lobster meat (fw). A statistically significant increase in activity concentrations of (137)Cs in the meat was observed in the summer months for both crab and lobster. The cause has not been investigated but may be related to the laying down of energy reserves during the active feeding period over the summer. At all times, uptake of (99)Tc is higher in the brown meat fraction of both crabs and lobsters, whilst (137)Cs is more uniformly distributed. These results are used to discuss the implications for sampling and monitoring programmes.

Limits to sustained energy intake VIII. Resting metabolic rate and organ morphology of laboratory mice lactating at thermoneutrality

We have previously shown that the food intake and milk production of MF1 laboratory mice lactating at 30°C, 21°C and 8°C increase as temperature declines. These data suggest that mice are not limited peripherally by the capacity of the mammary glands to produce milk but are limited by the capacity of the animal to dissipate body heat generated as a by-product of food processing and milk production. Here, we measure resting metabolic rate (RMR; prior to breeding and at peak lactation) and organ morphology (at peak lactation) in MF1 mice exposed to 30°C(thermoneutrality) and compare these traits with the same parameters measured previously in mice at 21°C and 8°C. The masses of visceral organs primarily responsible for energy flux (heart, lungs, stomach, small intestine,large intestine, liver, pancreas, spleen and kidneys) increased as temperature declined. The masses of all these organs differed between mice exposed to 8°C and 21°C, whereas only the masses of heart, liver and kidneys differed between mice at 21°C and 30°C. The increases in organ masses were paralleled by increases in RMR at peak lactation above the levels measured prior to breeding, with mice at 8°C and 21°C having significantly higher increases in RMR than mice at 30°C (29.6 kJ day–1, 25.5 kJ day–1 and 8.1 kJ day–1, respectively). The observed changes in visceral organs and RMR are consistent with both the heat dissipation and peripheral limit hypotheses. However, mice exposed to 8°C had substantially larger mammary glands than mice at 21°C or 30°C (2.450 g, 1.115 g and 0.956 g dry mass, respectively), which argues against the peripheral limitation hypothesis and is consistent with the heat dissipation limit hypothesis. In addition, cold exposure resulted in greater masses of brown adipose tissue,white adipose tissue, pelage and tail. We discuss these changes in the context of the potential thermoregulatory benefits from use of the heat generated as a by-product of milk synthesis.

Accumulation of lead, zinc, and cadmium in a wild population of Clethrionomys glareolus from an abandoned lead mine

Lead, zinc, and cadmium were determined in a range of tissues from wild populations of bank voles (Clethrionomys glareolus) trapped on an abandoned metalliferous mine site and a reference site. Estimated dietary intakes indicated that animals were exposed to elevated levels of all three metals at the mine site, and this was generally reflected in metal residues in body tissues. Lead concentrations were significantly higher in all tissues of animals from the mine compared to the reference site, while Cd was higher only in the kidney. There was evidence of age-accumulation (using total body weight as an index of age) of Cd in both the liver and kidney of mine site animals but no evidence of such accumulation of lead in bone. In contrast to Cd and Pb, Zn was lower in the tissues of mine site animals compared to the reference site. Based on critical tissue concentrations, the ecotoxicological risk to a wild population of bank voles (Clethrionomys glareolus), associated with total substrate levels of 1 microg g(-1) dry weight Cd and 700 microg g(-1) dry weight Zn at this mine site is negligible, but that associated with 4000 microg g(-1) dry weight Pb may be considered significant.

Specific interaction between the hop1 intracellular loop 3 domain of the human PAC(1) receptor and ARF

The PAC(1), VPAC(1) and VPAC(2) receptors are members of the secretin (Group II) family of G protein-coupled receptors. All members of this family activate adenylate cyclase and several have also been shown to activate phospholipase C. We have recently reported that the rat VPAC(1), VPAC(2) and PAC(1) receptors activate phospholipase D and that distinct pathways are utilised by two intracellular loop 3 splice variants of PAC(1), one of which is ARF-dependent. Phospholipase D activation by the hop1, but not the null (short), form of the PAC(1) receptor is sensitive to brefeldin A, an inhibitor of GTP exchange at ARF. We have expressed the null and hop1 intracellular loop 3 domains of the human PAC(1) receptor in bacteria as GST-fusion proteins and used them as peptide affinity matrices to determine whether a functional interaction exists between these domains and ARF. Using this GST pull-down assay, we have shown binding of the small G protein ARF6 to the hop1 but not the null domain of this receptor.

Isotopic processes in atmospheric chemistry

Trace gases are responsible for the atmospheric processes underlying air pollution and global change. Analysis of the distribution of stable isotopes in these gases is a way of gaining additional knowledge that may not otherwise be available. This approach requires knowledge of the isotopic signature of emissions sources and chemical reactions. This review focuses on the chemical physics of the processes underlying the distribution of stable isotopes in atmospheric gases.

Additional signals from VPAC/PAC family receptors

The receptors for the neuropeptides vasoactive intestinal polypeptide and pituitary adenylate cyclase-activating polypeptide are strong activators of adenylate cyclase, but recent evidence suggests that they can elicit a number of additional intracellular signals. Some of these are likely to be downstream of the conventional adenylate cyclase pathway, but it is now clear that others reflect novel primary coupling events of the receptors.

Food chain transfer of zinc within the ecosystems of old and modern metalliferous mine wastes

Concentrations of zinc in mine waste, vegetation, invertebrate and small mammals from abandoned mines and a modern mine site have been determined in order to assess and compare environmental risk. Very high concentrations of zinc in mine waste from all sites were reflected in vegetation zinc levels but not in invertebrates and mammals. Physiological regulatory control mechanisms operate to optimise zinc retention, and maintain homeostasis in animals by enhancing absorption of zinc from diets low in the trace element, and by buffering the potential accumulative effects of high dietary levels of the metal. Zinc is not considered to be an acute toxicity factor precluding colonisation of these mine sites by invertebrates and mammals though it maybe a selective force influencing the species composition and relative abundance in animal communities.

Quantifying 137Cs aggregated transfer coefficients in a semi-natural woodland ecosystem adjacent to a nuclear reprocessing facility

Radiocaesium (137Cs) activity concentrations and aggregated transfer factors (Tag values) were calculated for vascular plants, fungal fruiting bodies and invertebrates in a semi-natural Picea sitchensis woodland (Lady Wood) adjacent to the British Nuclear Fuels plc. reprocessing facility at Sellafield, Cumbria, UK. The Tag values for vascular plants ranged from 7.1 x 10(-4) - 1.9 x 10(-2) m2 kg(-1), the maximum value being for Pteridium aquilinum. Fungal fruiting bodies had higher Tag values (1.9 x 10(-3) - 1.8 x 10(-1) m2 kg(-1)) than vascular plants, with a maximum value for Mycena galericulata. None of the activity concentrations for edible foodstuffs collected within this study (fungi and berries) exceeded the EC recommended limits of 137Cs in foodstuffs grown within the UK. The invertebrate community sampled during the study had Tag values ranging from 3.4 x 10(-4) to 1.3 x 10(-2) m2 kg(-1). There were no systematic differences in 137Cs activity concentration between invertebrate guilds, or between seasonal cohorts within guilds. The invertebrates in Lady Wood were exposed to a dose from 137Cs (internal gamma + beta and external gamma) ranging between 4.37 x 10(-4) and 6.40 x 10(-4) mGy day(-1). Including dose from radionuclides other than 137Cs and accounting for uncertainties due to the relative biological effectiveness of differing radionuclides could increase total dose by approximately an order of magnitude. These dose rates are at least three orders of magnitude lower than the 1 mGy d(-1) level at which harm may be caused to terrestrial biota, hence the risk to the invertebrate community from the effects of ionising radiation in Lady Wood is low.

Selective binding of collagen subtypes by integrin alpha 1I, alpha 2I, and alpha 10I domains

Four integrins, namely alpha(1)beta(1), alpha(2)beta(1), alpha(10)beta(1), and alpha(11)beta(1), form a special subclass of cell adhesion receptors. They are all collagen receptors, and they recognize their ligands with an inserted domain (I domain) in their alpha subunit. We have produced the human integrin alpha(10)I domain as a recombinant protein to reveal its ligand binding specificity. In general, alpha(10)I did recognize collagen types I-VI and laminin-1 in a Mg(2+)-dependent manner, whereas its binding to tenascin was only slightly better than to albumin. When alpha(10)I was tested together with the alpha(1)I and alpha(2)I domains, all three I domains seemed to have their own collagen binding preferences. The integrin alpha(2)I domain bound much better to fibrillar collagens (I-III) than to basement membrane type IV collagen or to beaded filament-forming type VI collagen. Integrin alpha(1)I had the opposite binding pattern. The integrin alpha(10)I domain was similar to the alpha(1)I domain in that it bound very well to collagen types IV and VI. Based on the previously published atomic structures of the alpha(1)I and alpha(2)I domains, we modeled the structure of the alpha(10)I domain. The comparison of the three I domains revealed similarities and differences that could potentially explain their functional differences. Mutations were introduced into the alphaI domains, and their binding to types I, IV, and VI collagen was tested. In the alpha(2)I domain, Asp-219 is one of the amino acids previously suggested to interact directly with type I collagen. The corresponding amino acid in both the alpha(1)I and alpha(10)I domains is oppositely charged (Arg-218). The mutation D219R in the alpha(2)I domain changed the ligand binding pattern to resemble that of the alpha(1)I and alpha(10)I domains and, vice versa, the R218D mutation in the alpha(1)I and alpha(10)I domains created an alpha(2)I domain-like ligand binding pattern. Thus, all three collagen receptors appear to differ in their ability to recognize distinct collagen subtypes. The relatively small structural differences on their collagen binding surfaces may explain the functional specifics.

Recent trends in organochlorine residues in mussels (Mytilus edulis) from the Mersey Estuary

Blue mussels (Mytilus edulis) taken from several sites in the Mersey Estuary, an urban-industrial water body in NW England, have been analyzed for residues of the persistent organochlorines, DDT, PCB congeners nos. 28, 52, 101, 118, 138, 153 and 180 (ICES7), and alpha-MHCH (alpha-methyl hexachlorocyclohexane). The concentration range for sigmaPCB (ICES7) was 13.9-34.9 microg kg(-1) in 1994 compared with 9.6-31.9 microg kg(-1) in 1998, whilst the equivalent concentrations of sigmaDDT were 8.9-32.4 microg kg(-1) and 4.5-16.8 microg kg(-1), respectively. The concentration of alpha-MHCH, an organochlorine largely restricted to the Mersey Estuary, was 1.2-11 microg kg(-1) in 1994 and 0.3-1.3 microg kg(-1) in 1998. At both sampling dates the inner estuary sites of Rock Ferry and Egremont were more contaminated than the outer estuary sites of New Brighton. Dove Point and Caldy Blacks. The lower concentrations of organochlorines in mussels in 1998 compared with 1994 are thought to be early evidence of significant improvements in water quality derived from major capital investment in the treatment of industrial effluents and sewage wastewater, linked to a combination of stricter legislative controls and the environmental benefits from the adoption of new, clean technologies in manufacturing.

Effects of low birth weight on insulin resistance syndrome in caucasian and African-American children

OBJECTIVE

To examine the effects of low birth weight (LBW) on the components of insulin resistance syndrome (IRS) in Caucasian and African-American children aged 4-14 years (n = 560 observations among 139 subjects).

RESEARCH DESIGN AND METHODS

A linear random-effects modeling analysis with repeated measures (average four annual visits per child) was conducted to examine the associations between LBW and the components of IRS and their developmental trends over age. Fasting glucose, insulin, and lipids were assessed after an overnight fast; insulin action and secretion were determined by the tolbutamide-modified frequently sampled intravenous glucose tolerance test; and body composition was assessed by dual energy X-ray absorptiometry and computed tomography.

RESULTS

LBW was significantly associated with increased fasting insulin concentration and visceral fat mass, decreased acute insulin response, beta-cell function, and HDL cholesterol among African-American children. Among children with LBW, there were significant differences in fasting insulin, insulin sensitivity, acute insulin response, and HDL cholesterol between Caucasians and African-Americans. LBW was significantly associated with faster decrease in acute insulin response and increase in triglycerides with regard to age. The hyperbolic function between insulin sensitivity and beta-cell function was retarded among children with LBW (P = 0.04). In addition, there was a significant interaction between LBW and ethnicity in relation to fasting insulin (P < 0.05) and visceral fat (P = 0.05).

CONCLUSIONS

LBW may predict the risk of the IRS and its progression over age in childhood, and this effect may be more pronounced among African-American children.

Increase in hepatic arterial blood flow after transjugular intrahepatic portosystemic shunt creation and its potential predictive value of postprocedural encephalopathy and mortality

PURPOSE

To determine (i) whether there is a significant increase in hepatic artery blood flow (HABF) after transjugular intrahepatic portosystemic shunt (TIPS) creation and (ii) whether the extent of incremental increase in HABF is predictive of clinical outcome after TIPS creation.

MATERIALS AND METHODS

Prospective, nonrandomized, nonblinded duplex Doppler ultrasound (US) examinations were performed on 24 consecutive patients (19 men; Child Class A/B/C: 4/12/8, respectively) with a mean age of 52.8 years who were referred for TIPS creation for variceal bleeding. Peak hepatic artery velocity and vessel dimensions were used to calculate the hepatic arterial blood flow (HABF) before and after TIPS creation. Patients were clinically followed in the gastrohepatology clinic and TIPS US surveillance was performed at 1 and 3 months to assess shunt function. The extent of incremental increase in HABF was analyzed as a predictor of post-TIPS encephalopathy and/or death.

RESULTS

The technical success rate of TIPS creation was 100%. The shunt diameters were either 10 mm (n = 11) or 12 mm (n = 13). TIPS resulted in a significant reduction in the portosystemic gradient from 24.3 mm Hg +/- 5.7 to 9.3 mm Hg +/- 2.9 (P <.001). The hepatic artery peak systolic velocity and HABF increased significantly after TIPS creation, from 60.8 cm/sec +/- 26.7 to 121 cm/sec +/- 51.5 (P <.001) and from 254.2 mL/min +/- 142.2 to 507.8 mL/min +/- 261.3 (P <.001), respectively. The average incremental increase in HABF from pre-TIPS to post-TIPS was 253.6 mL/min +/- 174.2 and the average decremental decrease in portosystemic gradient was 15.0 mm Hg +/- 5.3, but there was no significant correlation (r = 0.04; P =.86) between the two. All shunts were patent at 30 and 90 days without sonographic evidence of shunt dysfunction. After TIPS creation, new or worsened encephalopathy developed in five patients at 30 days and in an additional three at 90 days. They were all successfully managed medically. Three patients (12.5%) died within 30 days of the TIPS procedure. The extent of incremental increase in HABF after TIPS was variable and did not correlate with the development of 30-day and 90-day encephalopathy (P =.41 and P =.83, respectively) or 30-day mortality (P =.2).

CONCLUSIONS

HABF increases significantly after TIPS but is not predictive of clinical outcome. The significance of the incremental increase is yet to be determined.

Genetic divergence of peripherally disjunct populations of the gastropod Batillariella estuarina in the Houtman Abrolhos Islands, Western Australia

Geographically disjunct populations are unusual in marine species, but the Houtman Abrolhos Islands, Western Australia, provide opportunities to study highly disjunct peripheral isolates of several species. The intertidal snail Batillariella estuarina occurs in isolated tidal ponds in the Abrolhos Islands, where it is at its northern limit, disjunct from mainland populations by 600-900 km. The species is thus disjunct both geographically and among the peripherally isolated populations in the Abrolhos Islands. Comparisons of allozymes at 11 polymorphic loci were made among populations from 10 ponds in the Abrolhos Islands and six sites from relatively continuous tidal flats at Albany, 900 km away, the nearest major set of populations. Among all 16 populations, subdivision was high (FST = 0.455). Although there were subtle differences between the geographical regions, the large majority of divergence occurred among the isolated ponds in the Abrolhos (FST = 0.441), and divergence on the tidal flats at Albany was only moderate (FST = 0.085). Characteristic of peripheral isolates, the pond populations have less polymorphism and fewer alleles than the more connected populations at Albany. Combined with evidence of genetic divergence in the gastropods Bembicium vittatum and Austrocochlea constricta, which have very similar geographical distributions to that of B. estuarina, these results indicate the potential evolutionary significance of peripherally isolated marine populations in the unusual habitats of the Abrolhos Islands.

A fragment library based on Gaussian mixtures predicting favorable molecular interactions

Here, a protein atom-ligand fragment interaction library is described. The library is based on experimentally solved structures of protein-ligand and protein-protein complexes deposited in the Protein Data Bank (PDB) and it is able to characterize binding sites given a ligand structure suitable for a protein. A set of 30 ligand fragment types were defined to include three or more atoms in order to unambiguously define a frame of reference for interactions of ligand atoms with their receptor proteins. Interactions between ligand fragments and 24 classes of protein target atoms plus a water oxygen atom were collected and segregated according to type. The spatial distributions of individual fragment - target atom pairs were visually inspected in order to obtain rough-grained constraints on the interaction volumes. Data fulfilling these constraints were given as input to an iterative expectation-maximization algorithm that produces as output maximum likelihood estimates of the parameters of the finite Gaussian mixture models. Concepts of statistical pattern recognition and the resulting mixture model densities are used (i) to predict the detailed interactions between Chlorella virus DNA ligase and the adenine ring of its ligand and (ii) to evaluate the "error" in prediction for both the training and validation sets of protein-ligand interaction found in the PDB. These analyses demonstrate that this approach can successfully narrow down the possibilities for both the interacting protein atom type and its location relative to a ligand fragment.

The FAD-PAS domain as a sensor for behavioral responses in Escherichia coli

Aer, the aerotaxis receptor in Escherichia coli, is a member of a novel class of flavoproteins that act as redox sensors. The internal energy of the cell is coupled to the redox state of the electron transport system, and this status is sensed by Aer(FAD). This is a more versatile sensory response system than if E. coli sensed oxygen per se. Energy-depleting conditions that decrease electron transport also alter the redox state of the electron transport system. Aer responds by sending a signal to the flagellar motor to change direction. The output of other sensory systems that utilize redox sensors is more commonly transcriptional regulation than a behavioral response. Analysis in silico showed Aer to be part of a superfamily of PAS domain proteins that sense the intracellular environment. In Aer, FAD binds to the PAS domain. By using site-specific mutagenesis, residues critical for FAD binding and sensory transduction were identified in the PAS domain. The PAS domain appears to interact with a linker region in the C-terminus. The linker region is a member of a HAMP domain family, which has signal transduction roles in other systems.

Influence of leptin on changes in body fat during growth in African American and white children

OBJECTIVE

The aim of this study was to determine whether initial levels or temporal changes in fasting leptin were associated with longitudinal changes in body-fat mass in children.

RESEARCH METHODS AND PROCEDURES

The study group consisted of 85 children (42 white and 43 African American) with a mean initial age of 8.1 +/- 0.1 years. The children had between three and six annual visits for repeated measurements of body composition by DXA and fasting leptin level. Fat mass and fasting leptin level were not normally distributed and were log-transformed. Data were analyzed using SAS Proc mixed growth models, with log fat as the dependent variable.

RESULTS

Initial leptin level was a significant predictor of the change in fat mass over time (p < 0.0001), with high initial leptin levels resulting in increased fat gain, independent of initial fat levels. This relationship remained significant when the data were analyzed separately by race (whites, p < 0.0001; African Americans, p = 0.008). The relationship between the initial level of leptin and the change in fat mass was not modified by race, sex, or Tanner Stage. The rate of change in leptin during the study was significantly related to the rate of change in fat mass in African Americans (p = 0.008) but not in whites (p = 0.490).

DISCUSSION

In conclusion, high fasting leptin level at the start of the study was significantly associated with increasing fat mass in this cohort, indicating that the children may be developing resistance to the effects of leptin.

Adenine recognition: a motif present in ATP-, CoA-, NAD-, NADP-, and FAD-dependent proteins

Adenosine triphosphate (ATP) plays an essential role in energy transfer within the cell. In the form of NAD, adenine participates in multiple redox reactions. Phosphorylation and ATP-hydrolysis reactions have key roles in signal transduction and regulation of many proteins, especially enzymes. In each cell, proteins with many different functions use adenine and its derivatives as ligands; adenine, of course, is present in DNA and RNA. We show that an adenine binding motif, which differs according to the backbone chain direction of a loop that binds adenine (and in one variant by the participation of an aspartate side-chain), is common to many proteins; it was found from an analysis of all adenylate-containing protein structures from the Protein Data Bank. Indeed, 224 protein-ligand complexes (86 different proteins) from a total of 645 protein structure files bind ATP, CoA, NAD, NADP, FAD, or other adenine-containing ligands, and use the same structural elements to recognize adenine, regardless of whether the ligand is a coenzyme, cofactor, substrate, or an allosteric effector. The common adenine-binding motif shown in this study is simple to construct. It uses only (1) backbone polar interactions that are not dependent on the protein sequence or particular properties of amino acid side-chains, and (2) nonspecific hydrophobic interactions. This is probably why so many different proteins with different functions use this motif to bind an adenylate-containing ligand. The adenylate-binding motif reported is present in "ancient proteins" common to all living organisms, suggesting that adenine-containing ligands and the common motif for binding them were exploited very early in evolution. The geometry of adenine binding by this motif mimics almost exactly the geometry of adenine base-pairing seen in DNA and RNA.

Barriers to follow-up of hypertensive patients

Lack of follow-up care for hypertension adversely affects health in urban communities. The authors designed this study to (1) evaluate the effectiveness of a specialized intervention program for hypertension follow-up and (2) evaluate the associations with loss to follow-up. They evaluated factors related to loss to follow-up to either a routine care medical clinic or a special primary care intervention program (the Competitive Initiative Program [CIP]). They also conducted interviews to provide in-depth information on the barriers to this program. They found that patients referred through the CIP were significantly more likely to receive follow-up care through a primary care provider. Cost of care, long waiting times, lack of physician continuity, and more pressing priorities explained the lack of follow-up care. Despite a program to provide health care at no cost to patients, lack of insurance and worries about cost are described as barriers to adequate follow-up for hypertension treatment.