Grb2 dominantly associates with dynamin II in human hepatocellular carcinoma HepG2 cells

The two SH3 domains and one SH2 domain containing adaptor protein Grb2 is an essential element of the Ras signaling pathway in multiple systems. The SH2 domain of Grb2 recognizes and interacts with phosphotyrosine residues on activated tyrosine kinases, whereas the SH3 domains bind to several proline-rich domain-containing proteins such as Sos1. To define the difference in Grb2-associated proteins in hepatocarcinoma cells, we performed coprecipitation analysis using recombinant GST-Grb2 fusion proteins and found that several protein components (p170, p125, p100, and p80) differently associated with GST-Grb2 proteins in human Chang liver and hepatocarcinoma HepG2 cells. Sos1 and p80 proteins dominantly bind to Grb2 fusion proteins in Chang liver, whereas p100 remarkably associate with Grb2 in HepG2 cells. Also GST-Grb2 SH2 proteins exclusively bound to the p46(Shc), p52(Shc), and p66(Shc) are important adaptors of the Ras pathway in HepG2 cells. The p100 protein has been identified as dynamin II. We observed that the N-SH3 and C-SH3 domains of Grb2 fusion proteins coprecipitated with dynamin II besides Sos1. These results suggest that dynamin II may be a functional molecule involved in Grb2-mediated signaling pathway on Ras activation for tumor progression and differentiation of hepatocarcinoma cells.

Orexin (hypocretin) neurons contain dynorphin

Orexins (also called hypocretins) are peptide neurotransmitters expressed in neurons of the lateral hypothalamic area (LHA). Mice lacking the orexin peptides develop narcolepsy-like symptoms, whereas mice with a selective loss of the orexin neurons develop hypophagia and severe obesity in addition to the narcolepsy phenotype. These different phenotypes suggest that orexin neurons may contain neurotransmitters besides orexin that regulate feeding and energy balance. Dynorphin neurons are common in the LHA, and dynorphin has been shown to influence feeding; hence, we studied whether dynorphin and orexin are colocalized. In rats, double-label in situ hybridization revealed that nearly all (94%) neurons expressing prepro-orexin mRNA also expressed prodynorphin mRNA. The converse was also true: 96% of neurons in the LHA containing prodynorphin mRNA also expressed prepro-orexin mRNA. Double-label immunohistochemistry confirmed that orexin-A and dynorphin-A peptides were highly colocalized in the LHA. Wild-type mice and orexin knock-out mice showed abundant prodynorphin mRNA-expressing neurons in the LHA, but orexin/ataxin-3 mice with a selective loss of the orexin neurons completely lacked prodynorphin mRNA in this area, further confirming that within the LHA, dynorphin expression is restricted to the orexin neurons. These findings suggest that dynorphin-A may play an important role in the function of the orexin neurons.

Differential expression of orexin receptors 1 and 2 in the rat brain

Orexins (hypocretins) are neuropeptides synthesized in the central nervous system exclusively by neurons of the lateral hypothalamus. Orexin-containing neurons have widespread projections and have been implicated in complex physiological functions including feeding behavior, sleep states, neuroendocrine function, and autonomic control. Two orexin receptors (OX(1)R and OX(2)R) have been identified, with distinct expression patterns throughout the brain, but a systematic examination of orexin receptor expression in the brain has not appeared. We used in situ hybridization histochemistry to examine the patterns of expression of mRNA for both orexin receptors throughout the brain. OX(1)R mRNA was observed in many brain regions including the prefrontal and infralimbic cortex, hippocampus, paraventricular thalamic nucleus, ventromedial hypothalamic nucleus, dorsal raphe nucleus, and locus coeruleus. OX(2)R mRNA was prominent in a complementary distribution including the cerebral cortex, septal nuclei, hippocampus, medial thalamic groups, raphe nuclei, and many hypothalamic nuclei including the tuberomammillary nucleus, dorsomedial nucleus, paraventricular nucleus, and ventral premammillary nucleus. The differential distribution of orexin receptors is consistent with the proposed multifaceted roles of orexin in regulating homeostasis and may explain the unique role of the OX(2)R receptor in regulating sleep state stability.

An unliganded thyroid hormone receptor causes severe neurological dysfunction

Congenital hypothyroidism and the thyroid hormone (T(3)) resistance syndrome are associated with severe central nervous system (CNS) dysfunction. Because thyroid hormones are thought to act principally by binding to their nuclear receptors (TRs), it is unexplained why TR knock-out animals are reported to have normal CNS structure and function. To investigate this discrepancy further, a T(3) binding mutation was introduced into the mouse TR-beta locus by homologous recombination. Because of this T(3) binding defect, the mutant TR constitutively interacts with corepressor proteins and mimics the hypothyroid state, regardless of the circulating thyroid hormone concentrations. Severe abnormalities in cerebellar development and function and abnormal hippocampal gene expression and learning were found. These findings demonstrate the specific and deleterious action of unliganded TR in the brain and suggest the importance of corepressors bound to TR in the pathogenesis of hypothyroidism.

Characterization of CART neurons in the rat and human hypothalamus

Cocaine- and amphetamine-regulated transcript (CART) is a recently described neuropeptide widely expressed in the rat brain. CART mRNA and peptides are found in hypothalamic sites such as the paraventricular nucleus (PVH), the supraoptic nucleus (SON), the lateral hypothalamic area (LHA), the dorsomedial nucleus of the hypothalamus (DMH), the arcuate nucleus (Arc), the periventricular nucleus (Pe), and the ventral premammillary nucleus (PMV). Intracerebroventricular administration of recombinant CART peptide decreases food intake and CART mRNA levels in the Arc are regulated by leptin. Leptin administration induces Fos expression in hypothalamic CART neurons in the PVH, the DMH, the Arc, and the PMV. In the current study, we used double label in situ hybridization histochemistry to investigate the potential direct action of leptin on hypothalamic CART neurons and to define the chemical identity of the hypothalamic CART neurons in the rat brain. We found that CART neurons in the Arc, DMH, and PMV express long form leptin-receptor mRNA, and the suppressor of cytokine signaling-3 (SOCS-3) mRNA after an acute dose of intravenous leptin. We also found that CART neurons in the parvicellular PVH, in the DMH and in the posterior Pe coexpress thyrotropin-releasing hormone (TRH) mRNA. CART neurons in the magnocellular PVH and in the SON coexpress dynorphin (DYN), and CART cell bodies in the LHA and in the posterior Pe coexpress melanin-concentrating hormone (MCH) and glutamic acid decarboxylase (GAD-67) mRNA. In the Arc, a few CART neurons coexpress neurotensin (NT) mRNA. In addition, we examined the distribution of CART immunoreactivity in the human hypothalamus. We found CART cell bodies in the PVH, in the SON, in the LHA, in the Arc (infundibular nucleus) and in the DMH. We also observed CART fibers throughout the hypothalamus, in the bed nucleus of the stria terminalis, and in the amygdala. Our results indicate that leptin directly acts on CART neurons in distinct nuclei of the rat hypothalamus. Furthermore, hypothalamic CART neurons coexpress neuropeptides involved in energy homeostasis, including MCH, TRH, DYN, and NT. The distribution of CART cell bodies and fibers in the human hypothalamus indicates that CART may also play a role in the regulation of energy homeostasis in humans.

Interleukin-4 induces two distinct GAS-binding complexes containing STAT6: evidence for DNA binding of STAT6 monomer

Treatment of tonsillar mononuclear cells with interleukin-4 (IL-4) rapidly induced the formation of two distinct complexes upon reaction of the cell extracts with the IL-4-responsive element (IL-4RE) of the CD23b promoter in the electrophoretic mobility sift assays (EMSA). The two complexes were detected with a similar activation kinetics upon IL-4 stimulation. They were both immunoreactive with antibodies to signal transducer and activator of transcription (STAT) 6. The upper complex, however, appeared more stable in the competitor oligomer binding assays and more resistant in the anti-phosphotyrosine antibody inhibition assays than the lower complex. Western blot analysis revealed a single peptide of 105 kDa reacting with anti-STAT6 antibodies, which ruled out the possibility for multiple isoforms of STAT6 in these cells. Subsequently, Southwestern analysis demonstrated that monomeric STAT6 in the IL-4-treated nuclear extract can bind the labeled IL-4RE in an activation-dependent manner. Our data strongly suggests that in addition to dimeric STAT6, monomeric STAT6, albeit with a lower affinity, can bind the IL-4RE/gamma activation site (GAS) upon IL-4-induced activation. Also, the upper and lower bands observed in EMSA are likely to represent dimeric and monomeric STAT6 bound to the IL-4RE oligomer, respectively. The functional implication of the STAT6 monomer binding to GAS in the IL-4-induced gene activation is discussed.

Self-reports and clinician-measured physical function among patients with low back pain: a comparison

OBJECTIVE

To determine the relationships among self-reported activity limitation and clinician-measured functional performance tests.

DESIGN

Case series survey.

SETTING

A referral-based orthopedic spine clinic in Houston, TX.

PATIENTS

Eighty-three patients (48 women, 35 men) with low back pain (LBP).

INTERVENTIONS

The Roland-Morris Disability Questionnaire (RMDQ) and a physical performance test (PPT) battery.

MAIN OUTCOME MEASURES

Self-reported activity limitation (eg, walking, bending, getting out of chair, putting on sock, doing heavy jobs) was assessed by the RMDQ. Clinician-measured functional performance was assessed with the PPT, a battery comprised 6 tests: lumbar flexion range of motion, a 50-foot walk at fastest speed, a 5-minute walk, 5 repetitions of sit-to-stand, 10 repetitions of trunk flexion, and loaded reach task (patients reached forward while holding a weight weighing 5% of their body weight).

RESULTS

Pearson's product-moment correlations between total RMDQ score and each of the performance tests ranged from.29 to.41. Point biserial correlations between individual RMDQ items and their corresponding performance tests were slightly lower, ranging from.20 to.33.

CONCLUSION

There were moderate correlations between self-reported activity limitation and corresponding clinician-measured performance tests. The unique perspective each method provides appears to be useful for a comprehensive understanding of physical function in patients with LBP.

Global phylogeography of a cryptic copepod species complex and reproductive isolation between genetically proximate "populations"

The copepod Eurytemora affinis has a broad geographic range within the Northern Hemisphere, inhabiting coastal regions of North America, Asia, and Europe. A phylogenetic approach was used to determine levels of genetic differentiation among populations of this species, and interpopulation crosses were performed to determine reproductive compatibility. DNA sequences from two mitochondrial genes, large subunit (16S) rRNA (450 bp) and cytochrome oxidase I (COI, 652 bp), were obtained from 38 populations spanning most of the species range and from two congeneric species, E. americana and E. herdmani. Phylogenetic analysis revealed a polytomy of highly divergent clades with maximum sequence divergences of 10% in 16S rRNA and 19% in COI. A power test (difference of a proportion) revealed that amount of sequence data collected was sufficient for resolving speciation events occurring at intervals greater than 300,000 years, but insufficient for determining whether speciation events were approximately simultaneous. Geographic and genetic distances were not correlated (Mantel's test; r = 0.023, P = 0.25), suggesting that populations had not differentiated through gradual isolation by distance. At finer spatial scales, there was almost no sharing of mtDNA haplotypes among proximate populations, indicating little genetic exchange even between nearby sites. Interpopulation crosses demonstrated reproductive incompatibility among genetically distinct populations, including those that were sympatric. Most notably, two geographically distant (4000 km) but genetically proximate (0.96% 16S, 0.15% COI) populations exhibited asymmetric reproductive isolation at the F2 generation. Large genetic divergences and reproductive isolation indicate that the morphologically conservative E. affinis constitutes a sibling species complex. Reproductive isolation between genetically proximate populations underscores the importance of using multiple measures to examine patterns of speciation.

IFN-gamma and IFN-alpha posttranscriptionally down-regulate the IL-4-induced IL-4 receptor gene expression

As Th1 and Th2 cytokines, IFN-gamma/alpha and IL-4 counterregulate diverse immune functions. In particular, IFN-gamma and IFN-alpha have been reported to markedly suppress the IL-4-induced IgE production and type II IgE receptor (FcepsilonRII/CD23) expression. Because modulation of IL-4R may be an important mechanism in the regulation of IL-4 response, we have investigated the effect of IFN-gamma/alpha on IL-4R expression and signal transduction mechanisms involved in this process. In human mononuclear cells and B cells isolated from tonsil or peripheral blood, IL-4 up-regulates IL-4R(alpha) expression at surface protein and mRNA levels, and the IL-4-induced IL-4R(alpha) is significantly down-regulated by both IFN-gamma and IFN-alpha to a similar extent. The inhibitory effects of IFN-gamma/alpha on the IL-4R mRNA expression require a lag period of about 8 h, and are sensitive to cycloheximide treatment, which suggests that the suppressive effect of IFNs on IL-4R gene expression is a secondary response requiring de novo synthesis of IFN-induced factors. Under such conditions that the inhibitory effects of IFNs are observed, IFNs do not affect the IL-4-induced STAT6 activation and IL-4R transcription, as analyzed by EMSA and nuclear run-on assays, respectively. Subsequently, mRNA stability studies have indicated that the action of IFN-gamma/alpha is primarily mediated by an accelerated decay of IL-4-induced IL-4R mRNA. Thus, it appears that, as already shown in the case of the IL-4-induced FcepsilonRII regulation, posttranscriptional inhibition of IL-4-inducible genes by mRNA destabilization is a common mechanism by which type I and II IFNs antagonize the IL-4 response in human immune cells.

The incidence of antimicrobial allergies in hospitalized patients: implications regarding prescribing patterns and emerging bacterial resistance

BACKGROUND

The development of antimicrobial guidelines is one way in which institutions attempt to control emerging resistance, but the real challenge falls on promoting and ensuring adherence to these guidelines. Investigating reasons for the prescribing of alternative antimicrobial agents outside of these guidelines is crucial for modifying practices that may adversely impact institutional antimicrobial goals.

METHODS

Retrospective cross-referencing of computerized pharmacy printouts and concurrent manual medical record review.

RESULTS

Approximately 25% (470/1893) of the patients requiring antimicrobial therapy reported an allergy to at least 1 antimicrobial agent. The most commonly reported antimicrobial allergy was penicillin (295/1893 [15.6%]). Eighty-five patients (18.1%) reported having an allergy to 2 or more antimicrobial agents. Only 4% (27/601) of the reported antimicrobial allergies contained documentation as to the nature of the specific allergic reactions, while a manual medical record review revealed that 32% (23/73) of the antimicrobial allergies contained documentation of the specific allergic reaction. Ninety-eight (39. 7%) of 247 patients reporting an allergy only to penicillin and/or cephalosporin received vancomycin in comparison with 247 (17.4%) of 1423 patients without any antimicrobial allergies (P<.001). Similarly, 53 (21.5%) of 247 patients with reported penicillin and/or cephalosporin allergies received levofloxacin compared with 114 (8.0%) of 1423 patients without any antimicrobial allergy (P<. 001).

CONCLUSION

The incidence of penicillin allergy at our institution exceeds population averages. This finding, in combination with limited documentation of drug allergies, appears to lead to the prescribing of alternative antimicrobial agents that do not fit into institutional antimicrobial guidelines and, in some instances, may put the patient at risk for infection and/or colonization with resistant organisms. Use of these alternative agents may adversely impact the ability to manage emerging antimicrobial resistance.

Chemical characterization of leptin-activated neurons in the rat brain

Leptin has profound effects on food intake, body weight, and neuroendocrine status. The lack of leptin results in hormonal and metabolic alterations and a dramatic increase in body weight. Leptin acts in the brain, especially in the hypothalamus; however, the central nervous system sites that respond to leptin have not been examined comprehensively. In this study, we explored systematically the distribution of leptin-activated neurons throughout the rat brain. Furthermore, we investigated the chemical identity of subsets of these leptin-activated cells. Fos-like immunoreactivity (Fos-IR) was investigated in the rat brain after two different doses of leptin (1.0 mg/kg and 5.0 mg/kg) at 2 hours and 6 hours after injections. The induction of Fos-IR was observed in hypothalamic nuclei, including the paraventricular nucleus (PVH), the retrochiasmatic area (RCA), the ventromedial nucleus (VMH), the dorsomedial nucleus (DMH), the arcuate nucleus (Arc), and the ventral premammillary nucleus (PMV). In addition, leptin-induced Fos-IR was found in several nuclei of the brainstem, including the superior lateral and external lateral subdivisions of the parabrachial nucleus (slPB and elPB, respectively), the supragenual nucleus, and the nucleus of the solitary tract (NTS). By using double-labeling immunohistochemistry or immunohistochemistry coupled with in situ hybridization, leptin-activated neurons were found that contained cocaine- and amphetamine-regulated transcript mRNA in several hypothalamic nuclei, including the RCA, Arc, DMH, and PMV. In the Arc and DMH, leptin-induced Fos-IR was observed in neurons that expressed neurotensin mRNA. Dynorphin neurons in the VMH and in the Arc also expressed Fos-IR. In the brainstem, we found that cholecystokinin neurons in the slPB and glucagon-like peptide-1 neurons in the NTS were activated by leptin. We also investigated the coexpression of Fos-IR and the long form of the leptin receptor (OBRb) mRNA. We found double-labeled neurons surrounding the median eminence and in the RCA, Arc, VMH, DMH, and PMV. However, in brainstem sites, very little OBRb mRNA was found; thus, there were very few double-labeled cells. These results suggest that leptin stimulates brain pathways containing neuropeptides that are involved in the regulation of energy balance, autonomic homeostasis, and neuroendocrine status.

Novel cathepsin D inhibitors block the formation of hyperphosphorylated tau fragments in hippocampus

Lysosomal disturbances may be a contributing factor to Alzheimer's disease. We used novel compounds to test if suppression of the lysosomal protease cathepsin D blocks production of known precursors to neurofibrillary tangles. Partial lysosomal dysfunction was induced in cultured hippocampal slices with a selective inhibitor of cathepsins B and L. This led within 48 h to hyperphosphorylated tau protein fragments recognized by antibodies against human tangles. Potent nonpeptidic cathepsin D inhibitors developed using combinatorial chemistry and structure-based design blocked production of the fragments in a dose-dependent fashion. Threshold was in the submicromolar range, with higher concentrations producing complete suppression. The effects were selective and not accompanied by pathophysiology. Comparable results were obtained with three structurally distinct inhibitors. These results support the hypothesis that cathepsin D links lysosomal dysfunction to the etiology of Alzheimer's disease and suggest a new approach to treating the disease.

Risk factor assessment in the management of patients with suspected deep venous thrombosis

BACKGROUND

To evaluate the prevalence of thrombosis risk factors in a group of patients undergoing venous duplex scanning (VDS) and to design a risk factor stratification model with the ability to improve the diagnostic yield of VDS.

METHODS

Risk factor assessment and VDS were performed on 1,000 patients with clinically suspected lower extremity deep vein thrombosis (DVT) and patients were divided into two groups based upon the outcome of their scan: those with and those without confirmed DVT. Univariate and multivariate logistic regression analyses were performed in order to determine the significance of each risk factor in relation to having a confirmed DVT.

RESULTS

There were 181 patients (18.1%) with confirmed DVT. A prior history of DVT/pulmonary embolism, malignancy, prior immobilization, and age over 70 were the most important risk factors associated with having a DVT confirmed on VDS. A novel risk factor stratification model was created utilizing the odds ratios of those factors found to be significant and the prevalence of DVT was found to be 92.4% in the high risk category, 11.5% in the moderate risk category, and 3.2% in the low risk category using this model.

CONCLUSIONS

Venous duplex scanning is established as the screening test of choice when one suspects the diagnosis of DVT despite the significant cost of performing and interpreting the test. We suggest that a better clinical model utilizing risk factor assessment may be the key to increasing the yield rate and cost-effectiveness of VDS by excluding low-risk patients from undergoing unnecessary testing.

Estrogen regulates gonadotropin-releasing hormone in the nervus terminalis of Xenopus laevis

The nervus terminalis or terminal nerve (TN) is a neuronal plexus found in the nasal cavity and rostral forebrain of most vertebrates. The hormone gonadotropin-releasing hormone (GnRH) is found in a population of TN neurons as well as hypothalamic neurons which regulate pituitary secretion of the gonadotropins. The GnRH-containing neurons of the TN appear to represent a rostral continuation of the hypothalamic population since they both originate from the olfactory placode and are frequently anatomically continuous. Previous studies have shown that the hypothalamic GnRH neurons are regulated by circulating estrogen levels. Ovariectomy decreases while estrogen administration increases GnRH content in these neurons. It is not known whether the GnRH-containing TN neurons are also regulated in a similar manner. This study demonstrates that ovariectomy and estrogen readministration alters GnRH-immunoreactive (ir) levels in the TN of female Xenopus laevis in a manner similar to that seen in the hypothalamus. One week after ovariectomy, the density of TN GnRH-ir fibers in the olfactory bulb region (one site of TN termination) is significantly decreased. In contrast, a significant increase in GnRH-ir TN fiber density is observed following estrogen readministration to ovariectomized frogs. These findings demonstrate that estrogen regulates GnRH metabolism in neurons of the TN.

Assessment of metered dose inhaler technique in family health service patients in Singapore

OBJECTIVE

To assess the metered-dose inhaler technique in polyclinic patients with chronic lung disease.

METHOD

A cross-sectional study was conducted in three polyclinics. The inhalation technique was assessed in six steps.

RESULTS

Only 7.1% of patients could perform all six steps correctly. Percentage of patients performing each of the following steps correctly were: preparation (89.1%), exhalation (53.8%), lip closure (69.2%), inhalation (57.7%), breath-holding (32.1%) and puff interval (35.4%).

CONCLUSION

This study showed a high incidence of incorrect usage of metered dose inhaler amongst polyclinic patients.

Causes and consequences of recent freshwater invasions by saltwater animals

Transitions from marine to freshwater habitats constitute dramatic shifts between 'adaptive zones' that have initiated the radiation and speciation of many taxa. As recently as 10?000 years ago, deglaciation resulted in marine fauna being trapped in freshwater lakes. In modern times, human activity has caused the acceleration of freshwater invasions from marine or brackish habitats, leading to serious environmental problems. The rapid pace of these invasions provides ideal opportunities for examining initial responses to environmental change and mechanisms involved in habitat transitions. Despite conservation implications and evolutionary applications, recent transitions to fresh water remain inadequately explored.

Potent, low-molecular-weight non-peptide inhibitors of malarial aspartyl protease plasmepsin II

A number of single-digit nanomolar, low-molecular-weight plasmepsin II aspartyl protease inhibitors have been identified using combinatorial chemistry and structure-based design. By identifying multiple, small-molecule inhibitors using the parallel synthesis of several focused libraries, it was possible to select for compounds with desirable characteristics including enzyme specificity and minimal binding to serum proteins. The best inhibitors identified have Ki's of 2-10 nM, molecular weights between 594 and 650 Da, between 3- and 15-fold selectivity toward plasmepsin II over cathepsin D, the most closely related human protease, good calculated log P values (2.86-4.56), and no apparent binding to human serum albumin at 1 mg/mL in an in vitro assay. These compounds represent the most potent non-peptide plasmepsin II inhibitors reported to date.

Up-regulation of interleukin-4 and CD23/FcepsilonRII in minimal change nephrotic syndrome

Although the pathogenesis of childhood minimal change nephrotic syndrome (MCNS) has not been clearly defined, the current hypothesis favors an involvement of T cell dysfunction. The symptom onset and the relapse of MCNS are frequently associated with allergy and increased IgE levels in sera. Since a T cell-derived cytokine interleukin-4 (IL-4) plays a key role in the regulation of IgE production and allergic response, we investigated the role of IL-4 in the pathophysiology of MCNS. Using fluorescence-activated cell scanning we observed a significantly higher expression of CD23, the type II IgE receptor (FcepsilonRII), on fresh B cells from active MCNS patients (n=22) compared with age-matched healthy normal controls (n=12). The upregulation of CD23 correlates with greater IL-4 activity in the culture supernatant of MCNS peripheral blood lymphocytes (PBLs) than normal PBLs stimulated by mitogens, as assessed by the CD23-inducing effect of the PBL supernatant on tonsillar B cells. Furthermore, Northern blot and reverse transcription-based polymerase chain reaction analysis have revealed significantly elevated levels of IL-4 mRNAs both in mitogen-stimulated and unstimulated MCNS PBLs, compared with healthy normals or disease controls with other renal disorders. Together these results strongly suggest that the upregulation of IL-4 in T cells may be part of the T cell dysfunction involved in MCNS.

Railroad bridge instrumentation with fiber-optic sensors

Fiber-optic sensors were installed on fatigue-critical components in the superstructure of a railroad bridge to monitor dynamic strains induced by trains crossing the bridge as well as to detect the onset of cracks. Each fiber Fabry-Perot interferometer (FFPI) strain gage was adhesively bonded to a stainless-steel strip to facilitate all-weather installation on the steel bridge members by spot welding. FFPI strain sensors were also installed on a rail at an approach to the bridge. Electrical resistive strain gages were colocated with the fiber-optic sensors on the bridge for the purpose of performance verification. In addition to the strain gages, fiber-optic continuity sensors for crack detection were bonded to the structure at critical locations. A telemetry system for transmitting the data over telephone lines was also installed at the bridge site. Dynamic response of the fiber-optic strain sensors is comparable with that of the electrical gages, and their performance has not degraded in the year since the initial installation.

Physical performance: differences in men and women with and without low back pain

OBJECTIVE

To determine the extent to which there may be major differences in scores on a battery of physical performance tasks among men with nonspecific, mechanical low back pain (LBP), women with LBP, healthy men, and healthy women.

DESIGN

Case series survey.

SETTING

A referral-based orthopedic clinic.

PATIENTS

Thirty-three men and 46 women with LBP. Control Subjects: Twenty-one men and 25 women healthy controls.

INTERVENTION

Completion of six clinician-assessed physical performance tasks and self-report inventories.

MAIN OUTCOME MEASURE

Performance scores on distance walked in 5 minutes, 50-foot walk at fastest speed, repeated sit-to-stand, repeated trunk flexion, loaded forward reach, and the Sorensen fatigue tasks.

RESULTS

Discriminant function analysis revealed that the four groups of subjects performed the physical tasks significantly different in two major ways: (1) healthy control subjects outperformed LBP patients, irrespective of gender, on tasks involving trunk control, coordination, and stability while withstanding heavy or quickly changing loads on the spine; (2) men outperformed women, irrespective of patient or nonpatient status, on tasks involving anthropometric features of limb length. The findings provide guidance on reasonable performance expectations for men and women patients with LBP. Future studies of treatment effectiveness also will be able to assess physical performance change in terms of the intersection between standards set by the men and women healthy control subjects and those of men and women patients. However, whether a return to nonpatient status is an appropriate treatment goal is left to future research.

Psychometric characteristics and clinical usefulness of physical performance tests in patients with low back pain

STUDY DESIGN

The psychometric properties and clinical use of a battery of physical performance measures were tested on 44 patients with low back pain and 48 healthy, pain-free control subjects.

OBJECTIVES

Reliability, validity, and clinical use of nine physical performance measures were evaluated.

SUMMARY OF BACKGROUND DATA

Although physical performance measures have potential use in evaluation, treatment planning, and determination of treatment outcome, there is sparse systematic investigation of their reliability, validity, and clinical use.

METHODS

Forty-four subjects with low back pain and 48 healthy pain-free subjects participated. The following physical performance measures were tested: distance walked in 5 minutes; 50-foot walk at fastest speed; 50-foot walk at preferred speed; 5 repetitions of a sit-to-stand task; 10 repetitions of a repeated trunk flexion task; timed up-and-go task; unloaded forward reach task; loaded forward reach task; and Sorensen fatigue test. Subjects were assessed twice on 2 days.

RESULTS

All measures had excellent intertester reliability (intraclass correlation coefficient [ICC]1,1 > 0.95). Test-retest (within session) reliability was adequate for all measures (ICC1,1 > 0.83) except repeated trunk flexion (ICC1,1 > 0.45) in the low back pain group. Test-retest (day-to-day) reliability ranged between 0.59 and 0.88 in the low back pain group and between 0.46 and 0.76 in the control group. Day-to-day reliability improved when the averages of two trials of repeated trunk flexion and sit-to-stand were used (0.76-0.91 low back pain group and 0.62-0.89 control group). Results of a multivariate analysis of variance showed a significant effect of group (F10,65 = 3.52, P = 0.001). Results of univariate analyses showed significant group differences on all measures except the 50-foot walk at preferred speed and unloaded forward reach. Self-report of disability was moderately correlated with the performance tasks (r = 0.400 to -0.603).

CONCLUSIONS

The results provide support for the use of these physical performance measures as a complement to patient self-report.

Differences in delta opioid receptor antinociception, binding, and mRNA levels between BALB/c and CXBK mice

Mu and delta opioid receptors have been demonstrated to mediate supraspinal opioid antinociception. Whereas the recombinant inbred CXBK mouse is notably deficient in mu opioid receptor antinociception, binding density, and mRNA (MOR-1) levels, little is known about delta opioid receptor processes in this strain. The present study thus compared CXBK mice and their BALB/c strain progenitors with respect to delta opioid antinociception, whole-brain receptor binding levels, and mRNA (DOR-1) levels. Following intracerebroventricular injections of the selective delta1 and delta2 opioids DPDPE and [d-Ala2]deltorphin II, respectively, CXBK mice displayed relatively lower antinociception on the tail-flick test, resulting in significantly increased ED50 values for both agonists in this strain. Decreased whole-brain specific binding of [3H][d-Ala2]deltorphin II, but not [3H]DPDPE, was also observed in CXBK mice. Solution hybridization with a probe for the DOR-1 revealed increased transcript levels in the caudate-putamen, frontal cortex, and spinal cord of this strain. The present data demonstrate a deficiency in delta1 and delta2 opioid antinociception in CXBK mice concomitant with reductions in whole-brain delta2 receptor binding and regional increases in DOR-1. Whether these observations are causally related remains to be clarified.

Chronic naltrexone differentially affects supraspinal delta-opioid receptor-mediated antinociception

The effects of chronic treatment with naltrexone, an opioid receptor antagonist, on delta1- and delta2-opioid receptor agonist-induced antinociception and ligand binding were investigated in mice. Antinociception by intracerebroventricular (i.c.v.) [D-Pen2,5]enkephalin (DPDPE) and [D-Ala2]deltorphin II, agonists selective for delta1- and delta2-opioid receptors, respectively, was blocked following subcutaneous (s.c.) implantation of a naltrexone pellet (7.5 mg) for 7 days. Removal of the naltrexone pellet was followed 24 h later by a decrease of 7.5-fold in the ED50 value of [D-Ala2]deltorphin II, but not that of DPDPE. In a whole brain homogenate the binding of [3H][D-Ala2]deltorphin II was increased twice as much as that of [3H]DPDPE. Chronic naltrexone treatment also produced an 8.6-fold decrease in the ED50 value of i.c.v. administered morphine. The increase in morphine potency was reversed to a control (placebo-treated mice) value by the selective delta2-opioid receptor antagonist, naltriben (25 pmol, i.c.v.). Thus, chronic naltrexone selectively increases delta2-opioid receptor-mediated antinociception, supporting the existence of delta opioid receptor subtypes with distinct adaptive characteristics. The data also indicate that delta2-opioid receptors are critically involved in the expression of morphine supersensitivity.