Preferential transport of synaptic vesicles across neuronal branches is regulated by the levels of the anterograde motor UNC-104/KIF1A in vivo

Asymmetric transport of cargo across axonal branches is a field of active research. Mechanisms contributing to preferential cargo transport along specific branches in vivo in wild type neurons are poorly understood. We find that anterograde synaptic vesicles preferentially enter the synaptic branch or pause at the branch point in Caenorhabditis elegans Posterior Lateral Mechanosensory neurons. The synaptic vesicle anterograde kinesin motor UNC-104/KIF1A regulates this vesicle behavior at the branch point. Reduced levels of functional UNC-104 cause vesicles to predominantly pause at the branch point and lose their preference for turning into the synaptic branch. SAM-4/Myrlysin, which aids in recruitment/activation of UNC-104 on synaptic vesicles, regulates vesicle behavior at the branch point similar to UNC-104. Increasing the levels of UNC-104 increases the preference of vesicles to go straight toward the asynaptic end. This suggests that the neuron optimizes UNC-104 levels on the cargo surface to maximize the fraction of vesicles entering the branch and minimize the fraction going to the asynaptic end.

Anterograde transport of synaptic vesicles is modulated by vesicular reversals and stationary cargo clusters

Stationary clusters of vesicles are a prominent feature of axonal transport, but little is known about their physiological and functional relevance to axonal transport. We investigate the role of vesicle motility characteristics in modulating the formation and lifetimes of such stationary clusters, and their effect on cargo flow. We develop a simulation model describing key features of axonal cargo transport, benchmarking the model against experiments in the Posterior Lateral Mechanosensory (PLM) neurons of C. elegans. Our simulations include multiple microtubule tracks, varied cargo motion states and accounts for dynamic cargo-cargo interactions. Our model also incorporates static obstacles to vesicle transport in the form of microtubule ends, stalled vesicles, and stationary mitochondria. We demonstrate, both in simulations and in an experimental system, that a reduction in reversal rates is associated with a higher proportion of long-lived stationary vesicle clusters and reduced net anterograde transport. Our simulations support the view that stationary clusters function as dynamic reservoirs of cargo vesicles, and reversals aid cargo in navigating obstacles and regulate cargo transport by modulating the proportion of stationary vesicle clusters along the neuronal process.

Morphological features of mitral annular calcification leading to systolic anterior motion of the mitral valve

Background

Systolic anterior motion (SAM) of the mitral valve (MV) can develop after mitral valve repair with placement of an annuloplasty ring. It is occasionally seen in patients with mitral annular calcification (MAC) but mechanisms have not been carefully delineated. Using 2-dimensional echocardiography we explored morphologic parameters which may contribute to SAM in patients with MAC.

Hypothesis

We hypothesized that in cases of MAC where SAM is present there would be anterior displacement of the valve by the posterior annular calcification.

Methods

From our echocardiographic database we identified 20 patients with severe MAC who also had SAM with definite septal contact. Each subject was paired with 2 controls free of MAC and 1 control with severe MAC but no SAM. All controls were matched for age, sex, BSA, and septal wall thickness (±1.5 mm). 2-D echocardiographic measurements were taken from the parasternal long-axis (PLAX), apical 3-chamber and apical 4-chamber views.

Results

MAC+SAM vs MAC no-SAM. Three notable differences were observed: MAC+SAM patients, as compared with MAC no-SAM, had a smaller left ventricular outflow tract (LVOT), longer anterior mitral leaflet, and greater displacement of the MV coaptation point towards the interventricular septum (Figure 1). Median values for these 3 factors were determined using the no-MAC controls; each MAC subject was then scored for number of factors exceeding those values. MAC+SAM patients had a mean score of 2.7 vs 1.1 for MAC no-SAM patients. By combining anterior mitral leaflet length and coaptation point-septal distance as a ratio we could effectively separate MAC+SAM vs MAC no-SAM when >0.9 with one exception (Figure 2). We also observed a smaller anteroposterior annular dimension in the MAC+SAM group.

MAC no-SAM vs no-MAC. Comparing these groups there were no differences in LVOT diameter or coaptation-septal distance; effective anterior mitral leaflet length was smaller in MAC no-SAM subjects vs no-MAC controls while anteroposterior dimension of the annulus was larger.

Conclusions

SAM develops in a subset of patients with severe calcification of the mitral annulus. These patients have a smaller anteroposterior annular dimension, possibly due to severe MAC. Other notable differences characterize MAC patients with SAM from those without. The LVOT is smaller, the effective anterior mitral leaflet length is longer, and the point of leaflet coaptation is displaced towards the septum. Using the ratio of anterior mitral leaflet length/coaptation point-septal distance in this study sample effectively separated those MAC patients with SAM from those without.

Funding Acknowledgement

Type of funding sources: None. Figure 1Figure 2

Repurposing the aldose reductase inhibitor and diabetic neuropathy drug epalrestat for the congenital disorder of glycosylation PMM2-CDG

Phosphomannomutase 2 deficiency, or PMM2-CDG, is the most common congenital disorder of glycosylation and affects over 1000 patients globally. There are no approved drugs that treat the symptoms or root cause of PMM2-CDG. To identify clinically actionable compounds that boost human PMM2 enzyme function, we performed a multispecies drug repurposing screen using a novel worm model of PMM2-CDG, followed by PMM2 enzyme functional studies in PMM2-CDG patient fibroblasts. Drug repurposing candidates from this study, and drug repurposing candidates from a previously published study using yeast models of PMM2-CDG, were tested for their effect on human PMM2 enzyme activity in PMM2-CDG fibroblasts. Of the 20 repurposing candidates discovered in the worm-based phenotypic screen, 12 were plant-based polyphenols. Insights from structure–activity relationships revealed epalrestat, the only antidiabetic aldose reductase inhibitor approved for use in humans, as a first-in-class PMM2 enzyme activator. Epalrestat increased PMM2 enzymatic activity in four PMM2-CDG patient fibroblast lines with genotypes R141H/F119L, R141H/E139K, R141H/N216I and R141H/F183S. PMM2 enzyme activity gains ranged from 30% to 400% over baseline, depending on genotype. Pharmacological inhibition of aldose reductase by epalrestat may shunt glucose from the polyol pathway to glucose-1,6-bisphosphate, which is an endogenous stabilizer and coactivator of PMM2 homodimerization. Epalrestat is a safe, oral and brain penetrant drug that was approved 27 years ago in Japan to treat diabetic neuropathy in geriatric populations. We demonstrate that epalrestat is the first small molecule activator of PMM2 enzyme activity with the potential to treat peripheral neuropathy and correct the underlying enzyme deficiency in a majority of pediatric and adult PMM2-CDG patients.

Editor's choice: Drug repurposing screens using worm and patient fibroblast models of PMM2-CDG led to the discovery of epalrestat, the first activator of PMM2 that targets the root cause of disease.

Cargo crowding at actin-rich regions along axons causes local traffic jams

Steady axonal cargo flow is central to the functioning of healthy neurons. However, a substantial fraction of cargo in axons remains stationary up to several minutes. We examine the transport of precursors of synaptic vesicles (pre-SVs), endosomes and mitochondria in Caenorhabditis elegans touch receptor neurons, showing that stationary cargo are predominantly present at actin-rich regions along the neuronal process. Stationary vesicles at actin-rich regions increase the propensity of moving vesicles to stall at the same location, resulting in traffic jams arising from physical crowding. Such local traffic jams at actin-rich regions are likely to be a general feature of axonal transport since they also occur in Drosophila neurons. Repeated touch stimulation of C. elegans reduces the density of stationary pre-SVs, indicating that these traffic jams can act as both sources and sinks of vesicles. This suggests that vesicles trapped in actin-rich regions are functional reservoirs that may contribute to maintaining robust cargo flow in the neuron. A video abstract of this article can be found at: Video S1; Video S2.

Inter-center variation in death or tracheostomy placement in infants with severe bronchopulmonary dysplasia

OBJECTIVE

To estimate the presence and sources of inter-center variation (ICV) in the risk of death or tracheostomy placement (D/T) among infants with severe bronchopulmonary dysplasia (sBPD)Study design:We analyzed the Children's Hospitals Neonatal Database between 2010 and 2013 to identify referred infants born <32 weeks' gestation with sBPD. The association between center and the primary outcome of D/T was analyzed by multivariable modeling. Hypothesized diagnoses/practices were included to determine if these explained any observed ICV in D/T.

RESULTS

D/T occurred in 280 (20%) of 1383 eligible infants from 21 centers. ICV was significant for D/T (range 2-46% by center, P<0.001) and tracheostomy placement (n=187, range 2-37%, P<0.001), but not death (n=93, range 0-19%, P=0.08). This association persisted in multivariable analysis (adjusted center-specific odds ratios for D/T varied 5.5-fold, P=0.009).

CONCLUSIONS

ICV in D/T is apparent among infants with sBPD. These results highlight that the indications for tracheostomy (and subsequent chronic ventilation) remain uncertain.

Racial/ethnic differences in weekend delivery after induction of labor

OBJECTIVE

To determine whether the frequency induction of labor (IOL) varies by day of the week based on maternal race/ethnicity.

STUDY DESIGN

Gravid women in the US from 2007 to 2010 were stratified into <34, 34 to 36, 37 to 38 and ⩾39 weeks. Multivariable analyses estimated the association between weekend delivery, race/ethnicity (categorized as non-Hispanic white, Hispanic white, black and 'other') and their interaction with induction.

RESULT

After 34 weeks, induction was less likely on the weekend (P<0.01) and less likely in black, Hispanic or 'other' women relative to non-Hispanic whites (P<0.01). However, there was a significant positive interaction between race/ethnicity and weekend delivery (P<0.001). During the late preterm gestation, weekend IOL was greater in black women (odds ratio, 1.08).

CONCLUSION

The difference in IOL by race/ethnicity increased with gestational age. This difference was least on the weekends.

Short-term outcomes after perinatal hypoxic ischemic encephalopathy: a report from the Children's Hospitals Neonatal Consortium HIE focus group

OBJECTIVE

To characterize infants affected with perinatal hypoxic ischemic encephalopathy (HIE) who were referred to regional neonatal intensive care units (NICUs) and their related short-term outcomes.

STUDY DESIGN

This is a descriptive study evaluating the data collected prospectively in the Children's Hospital Neonatal Database, comprised of 27 regional NICUs within their associated children's hospitals. A consecutive sample of 945 referred infants born ⩾36 weeks' gestation with perinatal HIE in the first 3 days of life over approximately 3 years (2010-July 2013) were included. Maternal and infant characteristics are described. Short-term outcomes were evaluated including medical comorbidities, mortality and status of survivors at discharge.

RESULT

High relative frequencies of maternal predisposing conditions, cesarean and operative vaginal deliveries were observed. Low Apgar scores, profound metabolic acidosis, extensive resuscitation in the delivery room, clinical and electroencephalographic (EEG) seizures, abnormal EEG background and brain imaging directly correlated with the severity of HIE. Therapeutic hypothermia was provided to 85% of infants, 15% of whom were classified as having mild HIE. Electrographic seizures were observed in 26% of the infants. Rates of complications and morbidities were similar to those reported in prior clinical trials and overall mortality was 15%.

CONCLUSION

Within this large contemporary cohort of newborns with perinatal HIE, the application of therapeutic hypothermia and associated neurodiagnostic studies appear to have expanded relative to reported clinical trials. Although seizure incidence and mortality were lower compared with those reported in the trials, it is unclear whether this represented improved outcomes or therapeutic drift with the treatment of milder disease.

The Children's Hospitals Neonatal Database: an overview of patient complexity, outcomes and variation in care

The Children's Hospitals Neonatal Consortium is a multicenter collaboration of leaders from 27 regional neonatal intensive care units (NICUs) who partnered with the Children's Hospital Association to develop the Children's Hospitals Neonatal Database (CHND), launched in 2010. The purpose of this report is to provide a first summary of the population of infants cared for in these NICUs, including representative diagnoses and short-term outcomes, as well as to characterize the participating NICUs and institutions. During the first 2 1/2 years of data collection, 40910 infants were eligible. Few were born inside these hospitals (2.8%) and the median gestational age at birth was 36 weeks. Surgical intervention (32%) was common; however, mortality (5.6%) was infrequent. Initial queries into diagnosis-specific inter-center variation in care practices and short-term outcomes, including length of stay, showed striking differences. The CHND provides a contemporary, national benchmark of short-term outcomes for infants with uncommon neonatal illnesses. These data will be valuable in counseling families and for conducting observational studies, clinical trials and collaborative quality improvement initiatives.

Predicting death or tracheostomy placement in infants with severe bronchopulmonary dysplasia

OBJECTIVE

To estimate the risk of death or tracheostomy placement (D/T) in infants with severe bronchopulmonary dysplasia (sBPD) born < 32 weeks' gestation referred to regional neonatal intensive care units.

STUDY DESIGN

We conducted a retrospective cohort study in infants born < 32 weeks' gestation with sBPD in 2010-2011, using the Children's Hospital Neonatal Database. sBPD was defined as the need for FiO2 ⩾ 0.3, nasal cannula support >2 l min(-1) or positive pressure at 36 weeks' post menstrual age. The primary outcome was D/T before discharge. Predictors associated with D/T in bivariable analyses (P < 0.2) were used to develop a multivariable logistic regression equation using 80% of the cohort. This equation was validated in the remaining 20% of infants.

RESULT

Of 793 eligible patients, the mean gestational age was 26 weeks' and the median age at referral was 6.4 weeks. D/T occurred in 20% of infants. Multivariable analysis showed that later gestational age at birth, later age at referral along with pulmonary management as the primary reason for referral, mechanical ventilation at the time of referral, clinically diagnosed pulmonary hypertension, systemic corticosteroids after referral and occurrence of a bloodstream infection after referral were each associated with D/T. The model performed well with validation (area under curve 0.86, goodness-of-fit χ(2), P = 0.66).

CONCLUSION

Seven clinical variables predicted D/T in this large, contemporary cohort with sBPD. These results can be used to inform clinicians who counsel families of affected infants and to assist in the design of future prospective trials.

Therapeutic interventions and short-term outcomes for infants with severe bronchopulmonary dysplasia born at <32 weeks' gestation

OBJECTIVE

To characterize the treatments and short-term outcomes in infants with severe bronchopulmonary dysplasia (sBPD) referred to regional neonatal intensive care units.

STUDY DESIGN

Infants born <32 weeks' gestation with sBPD were identified using the Children's Hospital Neonatal Database. Descriptive outcomes are reported.

RESULT

A total of 867 patients were eligible. On average, infants were born at 26 weeks' gestation and referred 43 days after birth. Infants frequently experienced lung injury (pneumonia: 24.1%; air leak: 9%) and received systemic corticosteroids (61%) and mechanical ventilation (median duration 37 days). Although 91% survived to discharge, the mean post-menstrual age was 47 weeks. Ongoing care such as supplemental oxygen (66%) and tracheostomy (5%) were frequently needed.

CONCLUSION

Referred infants with sBPD sustain multiple insults to lung function and development. Because affected infants have no proven, safe or efficacious therapy and endure an exceptional burden of care even after referral, urgent work is required to observe and improve their outcomes.

In vivo imaging of retrogradely transported synaptic vesicle proteins in Caenorhabditis elegans neurons

Axonal transport is an essential process that carries cargoes in the anterograde direction to the synapse and in the retrograde direction back to the cell body. We have developed a novel in vivo method to exclusively mark and dynamically track retrogradely moving compartments carrying specific endogenous synaptic vesicle proteins in the Caenorhabditis elegans model. Our method is based on the uptake of a fluorescently labeled anti-green fluorescent protein (GFP) antibody delivered in an animal expressing the synaptic vesicle protein synaptobrevin-1::GFP in neurons. We show that this method largely labels retrogradely moving compartments. Very little labeling is observed upon blocking vesicle exocytosis or if the synapse is physically separated from the cell body. The extent of labeling is also dependent on the dyenin-dynactin complex. These data support the interpretation that the labeling of synaptobrevin-1::GFP largely occurs after vesicle fusion and the major labeling likely takes place at the synapse. Further, we observe that the retrograde compartment carrying synaptobrevin contains synaptotagmin but lacks the endosomal marker RAB-5. This labeling method is very general and can be readily adapted to any transmembrane protein on synaptic vesicles with a GFP tag inside the vesicle and can also be extended to other model systems.

Dual role for microtubules in regulating cortical contractility during cytokinesis

Microtubules stimulate contractile-ring formation in the equatorial cortex and simultaneously suppress contractility in the polar cortex; how they accomplish these differing activities is incompletely understood. We measured the behavior of GFP-actin in mammalian cells treated with nocodazole under conditions that either completely eliminate microtubules or selectively disassemble astral microtubules. Selective disassembly of astral microtubules resulted in functional contractile rings that were wider than controls and had altered dynamic activity, as measured by FRAP. Complete microtubule disassembly or selective loss of astral microtubules resulted in wave-like contractile behavior of actin in the non-equatorial cortex, and mislocalization of myosin II and Rho. FRAP experiments showed that both contractility and actin polymerization contributed to the wave-like behavior of actin. Wave-like contractile behavior in anaphase cells was Rho-dependent. We conclude that dynamic astral microtubules function to suppress Rho activation in the non-equatorial cortex, limiting the contractile activity of the polar cortex.

Multiple enzyme activities of flavivirus proteins

Dengue viruses (DENV) have 5'-capped RNA genomes of (+) polarity and encode a single polyprotein precursor that is processed into mature viral proteins. NS2B, NS3 and NS5 proteins catalyse/activate enzyme activities that are required for key processes in the virus life cycle. The heterodimeric NS2B/NS3 is a serine protease required for processing. Using a high-throughput protease assay, we screened a small molecule chemical library and identified -200 compounds having > or = 50% inhibition. Moreover, NS3 exhibits RNA-stimulated NTPase, RNA helicase and the 5'-RNA triphosphatase activities. The NTPase and the 5'-RTPase activities of NS3 are stimulated by interaction with NS5. Moreover, the conserved, positively charged motif in DENV-2 NS3, 184RKRK, is required for RNA binding and modulates the RNA-dependent enzyme activities of NS3. To study viral replication, a variety of methods are used such as the in vitro RNA-dependent RNA polymerase assays that utilize lysates from DENV-2-infected mosquito or mammalian cells or the purified NS5 along with exogenous short subgenomic viral RNAs or the replicative intracellular membrane-bound viral RNAs as templates. In addition, a cell-based DENV-2 replicon RNA encoding a luciferase reporter is also used to examine the role of cis-acting elements within the 3' UTR and the RKRK motif in viral replication.

Solid-State Characterization of Buspirone Hydrochloride Polymorphs

The purpose of this study was to characterize Form 1 and Form 2 of buspirone hydrochloride, an anxiolytic medicine. The techniques used for characterization included microscopy (optical, hot stage, and scanning electron microscopy), thermal analysis (differential scanning calorimetry and thermogravimetric analysis), solid-state Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffractometry (XRPD), and Raman spectroscopy. Morphologically, Form 1 and Form 2 consist of plate and columnar crystals, respectively, with good filterability. Thermal analysis showed that the two forms are enantiotropic over the studied temperature range. The FTIR method was used successfully for the quantification of Form 1 in a mixture of Forms 1 and 2. The ratio of a characteristic peak to a reference peak and the chemometric method were used to obtain the calibration curve. The Raman peak shifts showed the difference between the two forms especially for the n-butyl group. The large number of distinguishable XRPD peaks in the region of 5 degrees to 30 degrees 2theta of the two polymorphs demonstrated that XRPD is a useful tool for quantitative and qualitative analysis of polymorphs.

Quantification of microtubule nucleation, growth and dynamics in wound-edge cells

Mammalian cells develop a polarized morphology and migrate directionally into a wound in a monolayer culture. To understand how microtubules contribute to these processes, we used GFP-tubulin to measure dynamic instability and GFP-EB1, a protein that marks microtubule plus-ends, to measure microtubule growth events at the centrosome and cell periphery. Growth events at the centrosome, or nucleation, do not show directional bias, but are equivalent toward and away from the wound. Cells with two centrosomes nucleated approximately twice as many microtubules/minute as cells with one centrosome. The average number of growing microtubules per microm2 at the cell periphery is similar for leading and trailing edges and for cells containing one or two centrosomes. In contrast to microtubule growth, measurement of the parameters of microtubule dynamic instability demonstrate that microtubules in the trailing edge are more dynamic than those in the leading edge. Inhibition of Rho with C3 transferase had no detectable effect on microtubule dynamics in the leading edge, but stimulated microtubule turnover in the trailing edge. Our data demonstrate that in wound-edge cells, microtubule nucleation is non-polarized, in contrast to microtubule dynamic instability, which is highly polarized, and that factors in addition to Rho contribute to microtubule stabilization.

Myosin-II-Dependent Localization and Dynamics of F-Actin during Cytokinesis

BACKGROUND

The assembly of an F-actin- and myosin-II-containing contractile ring (CR) is required for cytokinesis in eukaryotic cells. Interactions between myosin II and actin in the ring are believed to generate the force that constricts the cell into two daughters. The mechanism(s) that contribute to the spatially and temporally regulated assembly and disassembly of the CR at the cell equator are poorly understood.

RESULTS

We generated an LLCPK1 epithelial cell line that stably expresses GFP-actin. Live confocal imaging showed accumulation of GFP-actin in the equatorial cortex from late anaphase through cytokinesis. Fluorescence recovery after photobleaching (FRAP) experiments showed that actin in the CR is highly dynamic (t(1/2) = 26 s). In some cells, movement of GFP-actin toward the equatorial region was observed and contributed to FRAP. Blocking actin dynamic turnover with jasplakinolide demonstrates that dynamic actin is required for CR formation and cytokinesis. To test the role of myosin II in actin turnover and transport during CR formation, we inhibited myosin light-chain kinase with ML7 and myosin II ATPase activity with blebbistatin. Inhibition of myosin light-chain phosphorylation resulted in clearance of GFP-actin from the equatorial region, a reduction in myosin II in the furrow, and inhibition of cytokinesis. Treatment with blebbistatin did not block CR formation but reduced FRAP of GFP-actin and prevented completion of cytokinesis.

CONCLUSIONS

These results demonstrate that the majority of actin in the CR is highly dynamic and establish novel roles for myosin II in the retention and dynamic turnover of actin in the CR.

Naringin and naringenin inhibit nitrite-induced methemoglobin formation

Naringin and naringenin protect hemoglobin from nitrite-induced oxidation to methemoglobin. The protection is not observed when naringin and naringenin are added after the autocatalytic stage of the oxidation of hemoglobin by nitrite. The ability of naringin and naringenin to scavenge oxygen free radicals may be responsible for the action because superoxide, hydroxyl and other free radicals are implicated in promoting the autocatalytic stage of oxidation of hemoglobin by nitrite. Both compounds showed less ability to protect intact erythrocytes suggesting that they may not cross the erythrocyte membrane in sufficient amounts. Naringenin was more effective than naringin, probably because of the extra phenolic group in the aglycone.

Differences in early virus loads with different phenotypic variants of HIV-1 and SIV(cpz) in chimpanzees

OBJECTIVE

A comparative study of the replication kinetics of different HIV-1 variants (including SIV(cpz)) was undertaken to determine which viral characteristics were associated with sustained plasma viraemia in chimpanzees.

DESIGN

Plasma samples from chimpanzees infected with six different HIV-1 clade B isolates were compared with plasma samples from SIV(cpz-ant)-infected chimpanzees.

METHODS

A pan-clade quantitative competitive reverse transcriptase-polymerase chain reaction assay was developed based on conserved primer sequences recognizing M, N and O human lentiviruses as well as different SIV(cpz) isolates.

RESULTS

Important differences between early kinetics in the human lentivirus isolates as well as compared with the chimpanzee isolate SIV(cpz-ant) were observed. R5-dependent non-syncytium-inducing (NSI) isolates (5016, Ba-L, SIV(cpz)) were found to have relatively higher viral loads than the syncytium-inducing (SI), X4-dependent primary (SF2), T cell-adapted (IIIB) or X4/R5 (Han2, DH12) SI primary isolates.

CONCLUSION

Infection of chimpanzees with NSI R5-utilizing isolates correlated with persistent viraemia (approximately 10(4) RNA equivalents/ml) in contrast to transient viraemia observed after infection with SI X4-utilizing isolates.

Diversity of Salmonella serotypes in cull (market) dairy cows at slaughter

OBJECTIVE

To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter.

DESIGN

Cross-sectional study.

SAMPLE POPULATION

Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows.

PROCEDURE

During winter and summer 1996, cecal-colon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different.

RESULTS

Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S. Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter.

CONCLUSIONS AND CLINICAL RELEVANCE

58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.

Prevalence of Salmonella spp in cull (market) dairy cows at slaughter

OBJECTIVE

To determine the prevalence of Salmonella spp in the cecal-colon contents of cull (market) dairy cows at slaughter because of potential public health ramifications.

DESIGN

Survey study.

SAMPLE POPULATION

Cecal-colon contents collected from 5,087 cull (market) dairy cows at slaughter at 5 slaughter establishments across the United States.

PROCEDURE

During 2 periods of the year, winter (January and February) and summer (July through September), 5 cull (market) cow slaughter establishments in the United States--west (WE), southeast (SEE), central (CE), north central (NCE), and south central (SCE)--establishments were visited, and cecal-colon contents of cull dairy cows were obtained at the time of slaughter. Samples were examined by microbiologic culture at a single laboratory for Salmonella spp.

RESULTS

Salmonella spp were detected in 23.1% of cecal-colon content samples from cull dairy cows across the 5 slaughter establishments. The highest site prevalence (54.5%) was detected at the WE during the summer period, whereas the lowest was found at the CE during the summer (4.3%) and at the NCE during the winter (4.5%). Considerable variation in the daily prevalence of Salmonella spp was found, particularly at the WE and the SCE. Salmonella spp were isolated from 93% of cecal-colon contents collected on a summer day at the WE.

CONCLUSIONS AND CLINICAL RELEVANCE

Results strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process.

Helical CT angiography in evaluation of live kidney donors

BACKGROUND

Live kidney donor evaluation mandates anatomical and functional assessment of the donor kidney. Helical computed tomography (CT) with advanced 3-D techniques provides detailed description of the vascular, parenchymal, and collecting system.

METHODS

We compared the accuracy of helical CT angiography with intra-operative findings in the evaluation of 102 live kidney donors.

RESULTS

Identification of vascular anomalies was best on direct viewing of the axial images using interactive scrolling through the images and cine-loop paging. In 204 kidneys evaluated, a single renal artery was present in 74.5% and a single renal vein in 87.5%. Multiple renal arteries were more common on the left side (31%) vs the right side (20%). Early branching of the arteries was seen with equal frequency (approximately equal to 10%) on either side. Multiple renal veins were more often on the right side (20%) vs the left side (5%), and one patient was found to have double inferior vena cava. CT angiographic findings were concordant with the intra-operative findings in 97% of the cases, missing a small renal vein, an accessory artery that was visualized in retrospect, and a very early branch that was read as accessory artery. CT also revealed cortical cysts (four cases), duplex collecting system (two cases), hydronephrosis (one case), renal stone (one case), and liver haemangioma (two cases).

CONCLUSION

CT angiography is highly accurate for detecting vascular anomalies, and providing anatomical information. It may serve as the primary tool for donor evaluation.

Flagellin, a novel mediator of Salmonella-induced epithelial activation and systemic inflammation: I kappa B alpha degradation, induction of nitric oxide synthase, induction of proinflammatory mediators, and cardiovascular dysfunction

Gram-negative sepsis is mediated by the actions of proinflammatory genes induced in response to microbes and their products. We report that flagellin, the monomeric subunit of flagella, is a potent proinflammatory species released by Salmonella. Flagellin (1 microgram/ml) induces IkappaBalpha degradation, NF-kappaB nuclear translocation, and inducible NO synthase expression in cultured intestinal epithelial cells (IEC). Aflagellic Salmonella mutants do not induce NF-kappaB activation or NO production by cultured IEC. Antiserum to flagellin blocks NO production in IEC induced by medium conditioned by a variety of motile Gram-negative enteric pathogens (Escherichia coli, Salmonella muenchen, Serratia marcescens, Proteus mirabilis, and Proteus vulgaris). Flagellin, when injected systemically (approximately 10 microgram/mouse), induces systemic inflammation characterized by the systemic expression of a range of proinflammatory cytokines and chemokines and of inducible NO synthase. At higher doses (approximately 300 microgram/mouse), flagellin induces shock, characterized by hypotension, reduced vascular contractility in mice, and death. The effects of flagellin do not diminish in C3H/HeJ LPS-resistant mice, indicating that the Toll-like receptor-4 receptor is not involved in flagellin's actions. In LPS-resistant mice, i.p. injection of S. dublin flagellin or medium conditioned by wild-type S. dublin induces serum IFN-gamma and TNF-alpha, whereas medium conditioned by aflagellic mutants has no effect. Flagellin can be detected in the blood of rats with septic shock induced by live bacteria at approximately 1 microg/ml. We propose that flagellin released by Gram-negative pathogens may contribute to the inflammatory response by an LPS- and Toll-like receptor-4-independent pathway.

Results of preliminary clinical trials of the positron emission mammography system PEM-I: a dedicated breast imaging system producing glucose metabolic images using FDG

Early detection of breast cancer is crucial for efficient and effective treatment. We have developed an instrument for positron emission mammography (PEM) called PEM-I that performs high-resolution metabolic imaging of breast cancer. Images of glucose metabolism are obtained after injection of 75 MBq FDG. The PEM detectors are integrated into a conventional mammography system, allowing acquisition of the emission images immediately after the mammogram, without subject repositioning, and accurate coregistration of images from the 2 modalities. In this article, we present the results of the first clinical pilot study with the instrument.

METHODS

Sixteen subjects (age range, 34-76 y) were studied. All subjects were nondiabetic, nonpregnant, and without a history of cancer. They had recently been found to have suggestive mammography findings or a palpable breast mass and underwent lumpectomy or mastectomy within 2 wk of the study. Results from the PEM study were compared with those from mammography and pathology. A PEM test was classified positive (indicating the presence of cancer) if significant focal uptake was seen in the image or if the counting rate in the breast with suggestive findings was significantly higher than in the contralateral breast.

RESULTS

Of the 16 subjects studied, 14 were evaluable. Ten cancerous tumors and 4 benign tumors were confirmed by pathologic examination after complete removal of the tumor. PEM correctly detected the presence of disease in 8 of 10 subjects. Findings were false-negative in 2 instances and false-positive in none, giving the instrument 80% sensitivity, 100% specificity, and 86% accuracy.

CONCLUSION

Our preliminary results suggest that PEM can offer a noninvasive method for the diagnosis of breast cancer. Metabolic images from PEM contain unique information not available from conventional morphologic imaging techniques and aid in expeditiously establishing the diagnosis of cancer. In all subjects, the PEM images were of diagnostic quality, with an imaging time of 2-5 min.

Positron emission mammographic instrument: initial results

Performance characteristics of a positron emission mammographic (PEM) instrument were studied. This dedicated metabolic breast imaging system has spatial resolution of 2.8-mm full width at half maximum (FWHM), coincidence resolving time of 12-nsec FWHM, and absolute efficiency of 3%. Hot spots with diameter of 16 mm in a phantom with signal-to-background activity ratio of 6:1 were distinguishable with a scanning time of 5 minutes.

Specialty care for patients with epilepsy must become standard of care. Promotion of Specialty Care for Epilepsy Group

Epilepsy is a complex, common disorder with severe consequences for patients. The authors believe that a significant percentage of patients are receiving suboptimal care. The national standard of care needs to be upgraded to include the notion that patients with less than total seizure control or those suffering from any medication side-effects should be given the opportunity to receive specialty care by physicians with specific expertise in the field of epilepsy.

Clustering of trisomy 18 in Kuwait: Genetic predisposition or environmental?

BACKGROUND

This study describes 59 newborns with regular trisomy 18 (EdwardsA centAA syndrome, T18) who were ascertained clinically and cytogenetically at the Kuwait Medical Genetic Centre from 1994 to 1997, out of 118 T18 cases identified from 1980 to 1997.

MATERIALS AND METHODS

T18 cases were ascertained clinically and cytogenetically shortly after birth. In addition to assessing the T18 birth prevalence rate and confidence limits during the years 1994-1997, we investigated the possible etiological factors by a case-control study with normal healthy newborns. Studied factors included gender, parental age, birth order, abortion, clinical variables (presentation, amniotic fluid and mode of delivery), and survival.

RESULTS

The average T18 birth prevalence rate during the period was 8.95 per 10,000 live births (95% confidence limits 6.66-11.23). The T18 cases were mostly females, with a male:female ratio of 1:2.1, and the majority (53%) died before the second week of life. Maternal age above 30 years was found to be a significant factor for T18.

CONCLUSION

This high T18 birth prevalence rate suggests clustering of T18 in the highly inbred population of Kuwait. Such clustering may indicate a possible environmental, and to a lesser extent, genetic predisposition to aneuploidy nondisjunction.

Technique to obtain positron emission mammography images in registration with x-ray mammograms

X-ray mammograms reveal abnormal tissue densities, while metabolic images identify regions of abnormal metabolism. Conventional nuclear medicine and radiologic breast images must be acquired at different times with different patient positions making coregistration difficult. Accurate coregistration of metabolic and x-ray images of the breast is likely to be important when acquiring information about the location and diagnosis of suspicious lesions or tumors. Our PEM-1 (positron emission mammography) system detects metabolic activity within the breast. The two planar detectors are integrated into a conventional x-ray mammography unit. This arrangement simplifies the image registration process by allowing a breast metabolic image to be acquired immediately after performing an x-ray mammogram. The patient is not moved between procedures. A coregistration tool has also been developed. A thin plastic sheet with a wire frame protrudes from the side of the upper PEM detector. With the tool positioned over the suspicious area of the breast, a magnified film density image is made using the available x-ray equipment. A radio-opaque rectangular outline of the wire frame is visible on the film image. During a positron emission metabolic scan, detectors acquire a 49 x 59 mm2 image of the same region. The PEM detectors can be positioned anywhere along the width of the breast. This provides an image of a particular region of interest. Several contiguous images may be combined to provide a complete scan.

Differential promoter usage in prolactin receptor gene expression: hepatocyte nuclear factor 4 binds to and activates the promoter preferentially active in the liver

Characterization of the rat PRL receptor (PRLR) gene has revealed three separate untranslated exon 1 sequences, each associated with a different transcription start site and 5'-flanking sequence. We show by RT-PCR that exon 1A is expressed primarily in liver but is also detectable in ovary and mammary gland. Exon 1B expression is observed exclusively in the ovary, whereas exon 1C is expressed in all three tissues. Transient transfection of luciferase reporter constructs containing parts of the 5'-flanking regions (0.3-1.1 kb) of exon 1A, 1B, and 1C, respectively, showed activity of the 1A promoter in Chinese hamster ovary (CHO) cells, the human hepatoma cell line, HepG2, and the rat hepatoma cell line, H4II, which was 10- to 14-fold increased compared with the activity of the promoter-less luciferase vector. No activity of the 1A promoter was detected in the human mammary cell line, T-47D. Relative to a vector containing the Simian virus 40 (SV40) promoter, the 1A promoter had 20% activity in H4II cells and 1-3% activity in CHO and HepG2 cells. The 1B promoter produced a 6.1-fold increase of luciferase activity in CHO cells (approximately 2% of the SV40 promoter), whereas no significant activity was detected in HepG2, H4II, and T-47D cells. The 1C promoter was strongly active in T-47D cells (approximately 64-fold over control) and moderately active in the other cell lines tested (9- to 13-fold over control). 5'-Deletion analysis of the 1A promoter revealed that a fragment containing -83/ +81 bp, relative to the transcription start site, was sufficient to drive transcription in hepatoma cells, whereas this construct was inactive in CHO cells. Cotransfection of CHO cells with the -83/+81 construct and an expression vector encoding the liver-enriched transcription factor, hepatocyte nuclear factor 4 (HNF4), revealed a dose-dependent transactivation of the proximal 1A promoter with a maximal stimulation of approximately 10-fold. Electrophoretic mobility shift assays showed binding of HNF4 to the sequence -14/+24 of the 1A promoter, and mutational analysis revealed that the sequence GGGCAAAGTCA at position +11/+21 is required for this binding. We conclude that the 1A, 1B, and 1C promoters of the PRLR gene are used in a cell type- dependent way that may play a role in differential hormonal regulation of the gene. In particular, we have shown that HNF4 operates on the proximal 1A promoter and may be responsible, in combination with other factors, for the increased activity of this promoter in adult female liver.

Characterization of crystals of the thermostable DNA polymerase I from Thermus aquaticus

Thermus aquaticus DNA polymerase I is an enzyme that is of both physiological and technological interest. It carries out template-directed polymerization of DNA at elevated temperatures and is widely used in polymerase chain reaction (PCR). We have obtained crystals of the enzyme that diffracts X-rays to at least 3.0 A resolution in a cubic space group. Determination of the three-dimensional structure of the native enzyme along with those of relevant complexes will greatly enhance our knowledge of molecular events involved in DNA replication, will permit improvements in PCR, and will add to our knowledge of the structural bases of thermostability in proteins.

Comparative genotoxicity of 2,3'-O-cyclocytidine, beta-xylocytidine and 1-beta-D-arabinofuranosylcytosine in human tumor cell lines

We have investigated the genotoxicity of two 3'-derivatives of cytidine, 2,3'-O-cyclocytidine (3'-cycloC) and beta-xylocytidine (xyloC), in human leukemia and solid tumor cell lines. Both derivatives were found to be cytotoxic at micromolar concentrations. For example, in the alveolar tumor cell line A549 which was included in all experiments as a reference, drug concentrations required to induce 50% inhibition of cell growth (D50 values) equalled 55 microM for 3'-cycloC and 80 microM for xyloC. Compared with the response of this reference cell line, none of the solid tumor cell lines tested--representing five different malignancies--displayed significant hypersensitivity to these drugs, while the acute lymphoblastic leukemia cell lines proved to be hypersensitive (range of D50 values, 5-13 microM). To gain insight into the modes of cytotoxic action of xyloC and 3'-cycloC, we compared the effect on DNA metabolism of these compounds with that of 1-beta-D-arabinofuranosylcytosine (araC), a potent inhibitor of semi-conservative DNA replication and long-patch excision repair. As seen with araC, the xylo compound strongly inhibited both DNA replicative synthesis and the repair of DNA damage induced by UV light and 60Co gamma-radiation. In gamma-irradiated A549 cells, the extent of repair inhibition by 1 mM xyloC was approximately 40% of that inhibited by araC, and concomitant exposure of the irradiated cultures to xyloC plus araC gave rise to a synergistic response. Since araC was employed at a concentration (0.1 mM) which produced a maximal effect on DNA repair when applied alone, the observed synergistic response implies that the mode of action of xyloC on DNA repair is different from that of araC. In contrast to that observed with xyloC, 3'-cycloC proved to be a very weak inhibitor of DNA replication and repair, strongly suggesting that the genotoxic action of the latter analog may be through a mechanism other than inhibition of DNA synthesis.

Feasibility study for positron emission mammography

A feasibility study is presented for a small, low-cost, dedicated device for positron emission mammography. Two detector arrays above and below the breast would be placed in a conventional mammography unit. These detectors are sensitive to positron annihilation radiation, and are connected to a coincidence circuit and a multiplane image memory. Images of the distribution of positron-emitting isotope are obtained in real time by incrementing the memory location at the intersection of each line of response. Monte Carlo simulations of a breast phantom are compared with actual scans of this phantom in a conventional PET scanner. The simulations and experimental data are used to predict the performance of the proposed system. Spatial resolution experiments using very narrow bismuth germanate BGO crystals suggest that spatial resolutions of about 2 mm should be possible. The efficiency of the proposed device is about ten times that of a conventional brain scanner. The scatter fraction is greater, but the scattered radiation has a very flat distribution. By designing the device to fit in an existing mammography unit, conventional mammograms can be taken after the injection of the radio-pharmaceutical allowing exact registration of the emission and conventional mammographic images.

Effect of fluoride dentifrices on salivary fluoride levels in children

Fluoride dentifrices are well accepted for their caries preventive effects. The fluoride concentration in the oral fluids after tooth brushing with fluoride dentifrices may have an important relationship to the caries reducing capacity. The present study was aimed to clinically evaluate the salivary fluoride retention of dentifrices containing low fluoride concentration in 50 children, aged 7-9 years before, during and after the use of fluoride toothpaste. Estimation of fluoride in saliva was done using a Orion microprocessor ion analyser with a fluoride specific ion electrode. The results of the present study suggest that there is considerable salivary fluoride retention after brushing with fluoride dentifrices. The retention of fluoride in the saliva at a higher level even with the low fluoride concentration, proves the similar cariostatic effect as of higher concentration.

Hypernatraemic dehydration in the Hail region of Saudi Arabia

Infants presenting with hypernatraemic dehydration were studied prospectively in order to describe its incidence and the predisposing factors. Five hundred and twenty children with gastroenteritis were admitted to the Paediatric Unit of Hail General Hospital over a 1-year period from 1 June 1985 to 1 June 1986. Twenty-five children (4.8%) had hypernatraemia (Na+ greater than 150 mmol/l) and all 25 were under 1 year of age, 23 (92%) being under 6 months. Twenty (80%) came from families living in the villages and had a poor educational background. All the babies were bottle-fed. The majority of the mothers did not know how to prepare food hygienically and with the appropriate water/milk proportions. Most of the infants presented with high fever (+39 degrees C) and the majority were underweight for their age. Two babies died and one had evidence of neurological damage. This study indicates that the incidence of hypernatraemic dehydration is significant in this region and causes serious morbidity and mortality. It confirms the importance of breast-feeding and the need to educate the public in the proper preparation of bottle feeds when breast-feeding is not possible.