Evidence for negative selection in human primary fibroblasts to tolerate high somatic mutation loads upon treatment with multiple low doses of N-ethyl-N-nitrosourea

High-throughput sequencing at the single-cell and single-molecule level has shown that mutation rate is much higher in somatic cells than in the germline, with thousands of mutations accumulating with age in most human tissues. While there is now ample evidence that some of these mutations can clonally amplify and lead to disease, most notably cancer, the total burden of mutations a cell can tolerate without functional decline remains unknown. Here we addressed this question by exposing human primary fibroblasts multiple times to low doses of N-ethyl-N-nitrosourea (ENU) and quantitatively analyzing somatic mutation burden using single-cell whole genome sequencing. The results indicate that individual cells can sustain ∼60,000 single-nucleotide variants (SNVs) with only a slight adverse effect on growth rate. We found evidence for selection against potentially deleterious variants in gene coding regions as well as depletion of mutations in sequences associated with genetic pathways expressed in these human fibroblasts, most notably those relevant for maintaining basic cellular function and growth. However, no evidence of negative selection was found for variants in non-coding regions. We conclude that actively proliferating fibroblasts can tolerate very high levels of somatic mutations without major adverse effects on growth rate via negative selection against damaging coding mutations. Since most tissues in adult organisms have very limited capacity to select against mutations based on a growth disadvantage, these results suggest that a causal effect of somatic mutations in aging and disease cannot be ruled out.

Concurrent analysis of genome and transcriptome in one single cell

Thus far, multiple techniques for single cell analysis have been developed, yet we lack a relatively simple tool to assess DNA and RNA from the same cell at whole-transcriptome and whole-genome depths. Here we present an updated method for physical separation of cytoplasmic RNA from the nuclei, which allows for simultaneous studies of DNA and RNA from the same single cell. The method consists of three steps - 1) immobilization of a single cell on solid substrate, 2) hypotonic lysis of immobilized single cell, and 3) separation of cytosol containing aqueous phase and immobilized nucleus. We found that DNA and RNA extracted from single cell using our approach is suitable for downstream sequencing-based applications. We demonstrated that the coverage of transcriptome and genome sequencing data obtained after DNA/RNA separation is similar to that observed without separation. We also showed that the separation procedure does not create any noticeable bias in observed mutational load or mutation spectra. Thus, our method can serve as a tool for simultaneous complex analysis of the genome and transcriptome, providing necessary information on the relationship between somatic mutations and the regulation of gene expression.

Dynamic network-guided CRISPRi screen identifies CTCF-loop-constrained nonlinear enhancer gene regulatory activity during cell state transitions

Comprehensive enhancer discovery is challenging because most enhancers, especially those contributing to complex diseases, have weak effects on gene expression. Our gene regulatory network modeling identified that nonlinear enhancer gene regulation during cell state transitions can be leveraged to improve the sensitivity of enhancer discovery. Using human embryonic stem cell definitive endoderm differentiation as a dynamic transition system, we conducted a mid-transition CRISPRi-based enhancer screen. We discovered a comprehensive set of enhancers for each of the core endoderm-specifying transcription factors. Many enhancers had strong effects mid-transition but weak effects post-transition, consistent with the nonlinear temporal responses to enhancer perturbation predicted by the modeling. Integrating three-dimensional genomic information, we were able to develop a CTCF-loop-constrained Interaction Activity model that can better predict functional enhancers compared to models that rely on Hi-C-based enhancer-promoter contact frequency. Our study provides generalizable strategies for sensitive and systematic enhancer discovery in both normal and pathological cell state transitions.

Dynamic network-guided CRISPRi screen reveals CTCF loop-constrained nonlinear enhancer-gene regulatory activity in cell state transitions

Comprehensive enhancer discovery is challenging because most enhancers, especially those affected in complex diseases, have weak effects on gene expression. Our network modeling revealed that nonlinear enhancer-gene regulation during cell state transitions can be leveraged to improve the sensitivity of enhancer discovery. Utilizing hESC definitive endoderm differentiation as a dynamic transition system, we conducted a mid-transition CRISPRi-based enhancer screen. The screen discovered a comprehensive set of enhancers (4 to 9 per locus) for each of the core endoderm lineage-specifying transcription factors, and many enhancers had strong effects mid-transition but weak effects post-transition. Through integrating enhancer activity measurements and three-dimensional enhancer-promoter interaction information, we were able to develop a CTCF loop-constrained Interaction Activity (CIA) model that can better predict functional enhancers compared to models that rely on Hi-C-based enhancer-promoter contact frequency. Our study provides generalizable strategies for sensitive and more comprehensive enhancer discovery in both normal and pathological cell state transitions.

A mechanism for inheriting radiation-induced DNA damage

Radiation-damaged paternal DNA has been found to cause embryos of the second generation of nematode worms, but not the first, to die. The proposed mechanisms help to explain the observed lack of such an effect in humans.

MODELING REACTIVATED HETEROCHROMATIN USING AN AGING 3D CELL MODEL

Chromatin state and dynamics is modulated by chromatin interacting proteins, in particular histones and their post-translational modifications. We investigate the chromatin-bound proteome in aging to understand how DNA readout is misregulated in senescent cells. We focus on domains of reactivated heterochromatin, i.e. chromatin domains undergoing anomalous decondensation and decorated by histones co-modified with markers of condensed heterochromatin and active transcription. We optimize our mass spectrometry methods 3D cell models, and then apply them on B-cells retrieved from Ashkenazi Jews donors. In this cohort, we particularly focus on offsprings of exceptional longevity, i.e. individuals in their 70s with projected longer lifespan due to their centenarians ancestors. Preliminary data on 60 individuals revealed the enrichment of unusual histone modifications in the OPEL group, the group we utilize as indicator of projected longer lifespan. We have then applied biochemistry techniques to identify the role of these unusual modifications on chromatin readout.

Investigation of reversible histone acetylation and dynamics in gene expression regulation using 3D liver spheroid model

BACKGROUND

Three-dimensional (3D) cell culture has emerged as an alternative approach to 2D flat culture to model more accurately the phenotype of solid tissue in laboratories. Culturing cells in 3D more precisely recapitulates physiological conditions of tissues, as these cells reduce activities related to proliferation, focusing their energy consumption toward metabolism and homeostasis.

RESULTS

Here, we demonstrate that 3D liver spheroids are a suitable system to model chromatin dynamics and response to epigenetics inhibitors. To delay necrotic tissue formation despite proliferation arrest, we utilize rotating bioreactors that apply active media diffusion and low shearing forces. We demonstrate that the proteome and the metabolome of our model resemble typical liver functions. We prove that spheroids respond to sodium butyrate (NaBut) treatment, an inhibitor of histone deacetylases (HDACi), by upregulating histone acetylation and transcriptional activation. As expected, NaBut treatment impaired specific cellular functions, including the energy metabolism. More importantly, we demonstrate that spheroids reestablish their original proteome and transcriptome, including pre-treatment levels of histone acetylation, metabolism, and protein expression once the standard culture condition is restored after treatment. Given the slow replication rate (> 40 days) of cells in 3D spheroids, our model enables to monitor the recovery of approximately the same cells that underwent treatment, demonstrating that NaBut does not have long-lasting effects on histone acetylation and gene expression. These results suggest that our model system can be used to quantify molecular memory on chromatin.

CONCLUSION

Together, we established an innovative cell culture system that can be used to model anomalously decondensing chromatin in physiological cell growth and rule out epigenetics inheritance if cells recover the original phenotype after treatment. The transient epigenetics effects demonstrated here highlight the relevance of using a 3D culture model system that could be very useful in studies requiring long-term drug treatment conditions that would not be possible using a 2D cell monolayer system.

Genomic insights into host and parasite interactions during intracellular infection by Toxoplasma gondii

To gain insights into the molecular interactions of an intracellular pathogen and its host cell, we studied the gene expression and chromatin states of human fibroblasts infected with the Apicomplexan parasite Toxoplasma gondii. We show a striking activation of host cell genes that regulate a number of cellular processes, some of which are protective of the host cell, others likely to be advantageous to the pathogen. The simultaneous capture of host and parasite genomic information allowed us to gain insights into the regulation of the T. gondii genome. We show how chromatin accessibility and transcriptional profiling together permit novel annotation of the parasite's genome, including more accurate mapping of known genes and the identification of new genes and cis-regulatory elements. Motif analysis reveals not only the known T. gondii AP2 transcription factor-binding site but also a previously-undiscovered candidate TATA box-containing motif at one-quarter of promoters. By inferring the transcription factor and upstream cell signaling responses involved in the host cell, we can use genomic information to gain insights into T. gondii's perturbation of host cell physiology. Our resulting model builds on previously-described human host cell signalling responses to T. gondii infection, linked to induction of specific transcription factors, some of which appear to be solely protective of the host cell, others of which appear to be co-opted by the pathogen to enhance its own survival.

Global Level Quantification of Histone Post-Translational Modifications in a 3D Cell Culture Model of Hepatic Tissue

Flat cultures of mammalian cells are a widely used in vitro approach for understanding cell physiology, but this system is limited in modeling solid tissues due to unnaturally rapid cell replication. This is particularly challenging when modeling mature chromatin, as fast replicating cells are frequently involved in DNA replication and have a heterogeneous polyploid population. Presented below is a workflow for modeling, treating, and analyzing quiescent chromatin modifications using a three-dimensional (3D) cell culture system. Using this protocol, hepatocellular carcinoma cell lines are grown as reproducible 3D spheroids in an incubator providing active nutrient diffusion and low shearing forces. Treatment with sodium butyrate and sodium succinate induced an increase in histone acetylation and succinylation, respectively. Increases in levels of histone acetylation and succinylation are associated with a more open chromatin state. Spheroids are then collected for isolation of cell nuclei, from which histone proteins are extracted for the analysis of their post-translational modifications. Histone analysis is performed via liquid chromatography coupled online with tandem mass spectrometry, followed by an in-house computational pipeline. Finally, examples of data representation to investigate the frequency and occurrence of combinatorial histone marks are shown.

Evidence-based data from animal and human experimental studies on pain relief with antidepressants: a structured review

OBJECTIVE

It has been hypothesized that serotonin reuptake inhibitor antidepressants (ADs) are only weakly antinociceptive but augment noradrenergic (NA) antinociception. Thus, ADs with combined serotonergic (SN) and NA activity, (i.e., the serotonergic/noradrenergic (SN/NA) ADs) should have greater antinociceptive activity versus the NA ADs, which in turn should have more antinociceptive activity than the SN ADs. The objective of this structured review was to test this hypothesis by reviewing relevant basic science literature on the treatment of experimental pain with the above different types of ADs. DESIGN, SETTING, PARTICIPANTS, OUTCOME, MEASURES: Animal or human experimental AD pain treatment studies were located by the usual search methods. For animal studies only placebo-controlled studies were included for review. For human studies only double blind placebo-controlled studies were selected for review. The animal and human studies were then sorted according to the pain model represented, e.g., neuropathic pain model. Studies were then characterized according to the type of AD utilized, and the antinociceptive outcome of the AD trial.

RESULTS

Twenty-two animal studies and 5 human studies fulfilled the inclusion criteria of this structured review. Within the animal nonspecific pain model there were 10 SN/NA AD trials, 9 NA AD trials and 7 SN AD trials. Of these trials 100%, 88.9%, and 14.3% respectfully demonstrated a positive AD antinociceptive effect. Overall, for all the animal models there were 25 SN/NA, 9 NA, and 8 SN trials. Of these trials 92%, 88.9%, and 25% respectfully demonstrated a positive AD antinociceptive effect. For the human pain models, only the SN/NA ADs had been utilized in 7 trials. Here in 42.8% of the trials there was a reported antinociceptive effect.

CONCLUSIONS

Overall, the results of this structured review support the above hypothesis.

Interactive effects of dietary sodium and chloride on the incidence of spontaneous cardiomyopathy (round heart) in turkeys

Two pen trials were conducted in Utah, altitude 1,630 m, with Large White female turkey poults to evaluate effects of dietary Na and chloride (Cl) concentrations on live performance and deaths caused by spontaneous cardiomyopathy (STC, "round heart") from 0 to 35 d of age. A randomized block 2 x 2 factorial arrangement with four replicate pens per treatment was used. Pen size was 3.8 x 5.6 m. In each trial, four starter diets were formulated from a common basal diet (corn-soy-meat) to obtain the following sodium and chloride concentrations: High Na (0.24%):High Cl (0.40%); High Na (0.24%):Low Cl (0.16%); Low Na (0.14%):High Cl (0.40%); and Low Na (0.14%):Low Cl (0.16%). Supplements were NaCl, NaHCO3, NH4Cl, or combinations. After laboratory analysis, true values of Na were slightly lower than expected, Cl was near expected values to slightly low, and K was 1.145%. Body weight and feed conversion ratio at 35 d of age were unaffected in both trials. In both experiments, STC mortality was significantly reduced by the Low Na:High Cl treatment compared to the other treatments. In conclusion, a diet containing 0.10 to 0.12% Na and 0.38 to 0.40% Cl, significantly improved poult livability by reducing STC mortality without adverse effects on poult weight or feed conversion ratio.

Comparison of a picture-sort food-frequency questionnaire with 24-hour dietary recalls in an elderly Utah population

OBJECTIVE

To evaluate the 137-item Utah Picture-sort Food-frequency Questionnaire (FFQ) in the measurement of usual dietary intake in older adults.

DESIGN

The picture-sort FFQ was administered at baseline and again one year later. Three seasonal 24-hour dietary recall interviews were collected during the year between the two FFQs. Mean nutrient intakes were compared between methods and between administrations of the FFQ.

SETTING

The FFQ interviews were administered in respondents' homes or care-centres. The 24-hour diet recalls were conducted by telephone interview on random days of the week.

SUBJECTS

Two-hundred-and-eight men and women aged 55-84 years were recruited by random sample of controls from a case-control study of nutrition and bone health in Utah.

RESULTS

After adjustment for total energy intake, median Spearman rank correlation coefficients between the two picture-sort FFQs were 0.69 for men aged < or = 69 years, 0.66 for men aged > 69 years; and 0.68 for women aged < or = 69 years, 0.67 for women aged > 69 years. Median correlation coefficients between methods were 0.50 for men < or = 69 years old, 0.52 for men > 69 years old; 0.55 for women < or = 69 years old, 0.46 for women > 69 years old.

CONCLUSIONS

We report intake correlations between methods and administrations comparable to those reported in the literature for traditional paper-and-pencil FFQs and one other picture-sort method of FFQ. This dietary assessment method may improve ease and accuracy of response in this and other populations with low literacy levels, poor memory skill, impaired hearing, or poor vision.

International Headache Society headache diagnostic patterns in pain facility patients

OBJECTIVE

Previous studies have indicated that many patients with chronic pain (PWCP) referred to pain facilities for the treatment of neck and/or low back pain complain of associated headaches. The purpose of this study was to characterize the nature of these headaches according to International Headache Society (IHS) headache diagnostic criteria.

DESIGN

In preparation for this study, a questionnaire that reflected IHS headache diagnostic criteria was developed. All consecutive patients admitted to our pain facility complaining of headache completed this questionnaire and received a physical and neurologic examination focused on key aspects of headache. A headache interview was also conducted, using the questionnaire as a question guide. All questionnaires were entered in a computerized database, and IHS diagnoses were arrived at for each patient. As many IHS diagnoses as possible were assigned to each PWCP as long as IHS criteria were fulfilled. In addition, a frequency distribution for headache precipitants and neck-associated symptoms was developed and evaluated by discriminant analysis to determine the diagnostic value of these factors in relation to each IHS diagnostic group.

SETTING

Pain facility (multidisciplinary pain center).

PATIENTS

Consecutive PWCP.

RESULTS

Of 1,466 PWCP, 154 (10.5%) were identified as suffering from severe headache interfering with function. Of these, 55.8% indicated that their headaches were related to an injury for which they were seeking treatment and 83.7% had neck pain. Migraine headache represented the most common diagnostic group (90.3%), with cervicogenic headache representing the second most common (33.8%). Of the total group, 44.2% had more than one headache diagnosis, that is, there was overlap. Cervicogenic headache patients had the greatest percentage of overlap (94.2%), with migraine patients being second (68.3%). The most frequent headache precipitant was mental stress, followed by neck position and activity/exercise. The migraine and cervicogenic headache groups had a statistically significant greater number of neck-associated symptoms when compared with the remaining patients. Of the total headache group, 74.6% complained that they had a tender point at the back of their neck. Cervicogenic, migraine, and tension PWCP had the greatest frequency of head or neck tender points. The discriminant analysis for neck-associated symptoms yielded the following symptoms as the most common predictors of headache across IHS diagnostic groups: clues to onset were severe headache beginning at the neck or tender point and numbness in arms and legs; headache brought on by neck position and arms overhead; and neck symptoms consisting of a tender point in the neck and feeling severe headache in the neck.

CONCLUSIONS

Headache can and should be considered a frequent comorbid condition in PWCP. Because of the overlap data, more precise diagnostic criteria may be required to separate cervicogenic headache from migraine headache. Neck-associated symptoms seem to be important even to those PWCP diagnosed with migraine headache.

Chronic pain disability exaggeration/malingering and submaximal effort research

OBJECTIVE

This is the first review of chronic pain (CP) malingering/disease simulation research. The purpose of this review was to determine the prevalence of malingering within CP patients (CPPs), whether evidence exists that malingering can be detected within CPPs, and to suggest some avenues of research for this topic.

DESIGN

A computer and manual literature search produced 328 references related to malingering, disease simulation, dissimulation, symptom magnification syndrome, and submaximal effort. Of these, 68 related to one of these topics and to pain. The references were reviewed in detail, sorted into 12 topic areas, and placed into tabular form. These 12 topic areas addressed the following: existence of malingering within the CP setting; dissimulation, identification simulated (faked) facial expressions of pain; identification of malingering by questionnaire; identification of malingered sensory impairment; identification of malingered loss of hand grip strength; identification of submaximal effort by isometric strength testing; identification of submaximal or malingered effort by isokinetic strength testing; identification of submaximal or malingered effort by the method of coefficient of variation; self-deception; symptom magnification syndrome; and miscellaneous malingering identification studies. Each report, in each topic area, was rated for scientific quality according to guidelines developed by the Agency for Health Care, Policy and Research (AHCPR) for rating the level of evidence presented in the reviewed study. The AHCPR guidelines were then used to rate the strength and consistency of the research evidence in each topic area based on the type of evidence the reports represented. All review conclusions were based on the results of these ratings.

SETTING

Any medical setting reporting on either malingering or disease simulation, or dissimulation, or submaximal effort and pain.

PATIENTS

Normal volunteers, CPPs, or any group asked to produce a submaximal or malingered effort or a malingered test profile.

RESULTS

The reviewed studies indicated that malingering and dissimulation do occur within the CP setting. Malingering may be present in 1.25-10.4% of CPPs. However, because of poor study quality, these prevalence percentages are not reliable. The study evidence also indicated that malingering cannot be reliably identified by facial expression testing, questionnaire, sensory testing, or clinical examination. There was no acceptable scientific information on symptom magnification syndrome. Hand grip testing using the Jamar dynamometer and other types of isometric strength testing did not reliably discriminate between a submaximal/malingering effort and a maximal/best effort. However, isokinetic strength testing appeared to have potential for discriminating between maximal and submaximal effort and between best and malingered efforts. Repetitive testing with the coefficient of variation was not a reliable method for discriminating a real/best effort from a malingered effort.

CONCLUSIONS

Current data on the prevalence of malingering within CPPs is not consistent, and no conclusions can be drawn from these data. As yet, there is no reliable method for detecting malingering within CPPs, although isokinetic testing shows promise. Claims by professionals that such a determination can be made should be viewed with caution.

Breath ethane as a marker of reactive oxygen species during manipulation of diet and oxygen tension in rats

Breath ethane, O2 consumption, and CO2 production were analyzed in 24-mo-old female Fischer 344 rats that had been fed continuously ad libitum (AL) or restricted 30% of AL level (DR) diets since 6 wk of age. Rats were placed in a glass chamber that was first flushed with air, then with a gas mixture containing 12% O2. After equilibration, a sample of the outflow was collected in gas sampling bags for subsequent analyses of ethane and CO2. The O2 and CO2 levels were also directly monitored in the outflow of the chamber. O2 consumption and CO2 production increased for DR rats. Hypoxia decreased O2 consumption and CO2 production for the AL-fed and DR rats. These changes reflect changes in metabolic rate due to diet and PO2. A significant decrease in ethane generation was found in DR rats compared with AL-fed rats. Under normoxic conditions, breath ethane decreased from 2.20 to 1.61 pmol ethane/ml CO2. During hypoxia the levels of ethane generation increased, resulting in a DR-associated decrease in ethane from 2.60 to 1.90 pmol ethane/ml CO2. These results support the hypothesis that DR reduces the level of oxidative stress.

Chronic pain-associated depression: antecedent or consequence of chronic pain? A review

OBJECTIVE

To determine the current status for the association of chronic pain and depression and to review the evidence for whether depression is an antecedent or consequence of chronic pain (CP).

DESIGN

A computer and manual literature review yielded 191 studies that related to the pain-depression association. These reports were reviewed and sorted into seven categories relating to the topic of this paper. Eighty-three studies were then selected according to inclusion criteria and subjected to a structured review.

SETTING

Any medical treatment setting including pain treatment as inclusion criteria for selection of studies.

PATIENTS

Any patients with any type of chronic pain.

RESULTS

The reviewed studies were consistent in indicating that there is a statistical relationship between chronic pain and depression. For the relationship between pain and depression, there was greater support for the consequence and scar hypotheses than the antecedent hypothesis.

CONCLUSIONS

Depression is more common in chronic pain patients (CPPs) than in healthy controls as a consequence of the presence of CP. At pain onset, predisposition to depression (the scar hypothesis) may increase the likelihood for the development of depression in some CPPS. Because of difficulties in measuring depression in the presence of CP, the reviewed studies should be interpreted with caution.

Transcutaneous electrical nerve stimulation (TENS) treatment outcome in long-term users

OBJECTIVE

Previous reviewers of the literature on transcutaneous electrical nerve stimulation (TENS) outcome have concluded the following: (a) there are few long-term TENS follow-up studies, and (b) fewer studies have addressed the effect of long-term TENS use on outcome variables other than pain (e.g., function). DESIGN/SETTING/PARTICIPANTS/OUTCOME MEASURES: From a population of 2,003 chronic pain patients (CPPs) who bought a TENS device for pain management, 506 patients were randomly selected and interviewed by telephone long enough after purchase to allow at least 6 months of TENS use. The interview process used a structured "skip" questionnaire designed to assess the CPPs' perceptions regarding the effectiveness of TENS for a variety of outcome variables. Of the 506 CPPs interviewed, 376 (74.3%) had used their TENS device for 6 months or longer and were defined as long-term users. The responses of this group of CPPs to the telephone questionnaire were then subjected to statistical analysis.

RESULTS

Paired t-tests, correlated z-tests, SS Wilks, and chi-square tests demonstrated statistically significant change or improvement (p < 0.05) that paralleled the introduction of TENS use in the following outcome variables: less pain interference with work, home, and social activities; increased activity level and pain management; decreased use of other therapies (e.g., physical therapy, occupational therapy, chiropractic); decreased use of narcotics, tranquilizers, muscle relaxants, nonsteroidal anti-inflammatory drugs and steroids.

CONCLUSIONS

The results suggest that TENS is associated with improvement on multiple outcome variables in addition to pain relief for CPPs who are long-term users. Also, for some CPPs, long-term TENS use continues to be effective.

Age differences in sensitivity to H2O2- or NO-induced reductions in K(+)-evoked dopamine release from superfused striatal slices: reversals by PBN or Trolox

Previous research has indicated that many age-related functional alterations may be the result of a decreased ability of the organism to respond to oxidative stress (OS). However, this hypothesis is based on indirect indices of function (e.g., increased vulnerability of hepatocytes from senescent animals to H2O2-induced DNA damage, increases in lipofuscin accumulation). More direct tests of this hypothesis, especially as it relates to brain aging, have not been extensively undertaken. Present experiments were carried out to make such tests by examining age differences in the sensitivity to OS on reductions in striatal dopamine (DA) release. Thus, K(+)-evoked DA (K(+)-ERDA) release from superfused striatal slices from young (6-8 month) and old (24-25 month) animals was examined following either: (a) application of the NO-generator sodium nitroprusside or (b) preincubation with H2O2. In order to assess the specific effects of OS on muscarinic (mAChR) sensitivity, oxotremorine-enhancement of K(+) -ERDA was examined following incubation with H2O2. Results showed that the striatal tissue from the old animals showed greater sensitivity to both H2O2 and NO than young animals, and stimulated DA decreased at lower concentrations of these agents (e.g., NO--100 microM young, 30 microM old). In addition, H2O2 was also effective in reducing oxo-enhanced K(+)-ERDA and was more effective as a function of age. If the striatal tissue was incubated in either Trolox (alpha-tocopherol) or alpha-phenyl-n-tert-butyl nitrone (PBN) prior to OS, the negative effects of NO. and H2O2 were reversed in both age groups. Results are discussed in terms of age-related membrane and endogenous antioxidant alterations that could induce increases in sensitivity to OS and the specificity of antioxidants in reducing this sensitivity in key functional systems.

Physician limitations when assessing work capacity: a review

Literature evidence indicates that physicians have great difficulty in translating medical impairment into functional limitation and thereby establishing the work capacity or the residual functional capacity (RFC) of the injured worker. This is especially true for the chronic pain patient (CPP). Development of quantitative methods for the measurement of functional capacity (FC), have not improved the problems involved in the measurement of RFC and the translation of RFC into the demand minimum functional capacity (DMFC) of some job or jobs. The relationship between FC, RFC, work capacity and DMFC is reviewed. We have developed a method/battery for measuring RFC in CPPs utilizing the Dictionary of Occupational Titles (DOT) which is readily translatable into DMFC of some job or jobs. Suggestions are made for future directions in the measurement of work capacity.

Area specific alterations in muscarinic stimulated low Km GTPase activity in aging and Alzheimer's disease: implications for altered signal transduction

Carbachol-stimulated low Km GTPase activity (an index of muscarinic receptor-G protein coupling) was examined in hippocampus, basal ganglia, orbital frontal gyrus and superior frontal gyrus obtained from mature, aged and Alzheimer's Disease (AD) groups. Results indicated that carbachol-stimulated low Km GTPase activities in basal ganglia were as follows: mature controls > aged > AD, and there was a trend toward a similar pattern of decline in the hippocampus. No differences were seen in the two cortical areas examined; however, carbachol-stimulated low Km GTPase activity was small in the mature controls. Importantly, there were significant negative correlations between disease duration and carbachol-stimulated low Km GTPase activity in all areas examined except the orbital frontal gyrus. The longer the duration of the disease the lower the carbachol-stimulated low Km GTPase activity. Results suggest that age and disease-related changes in mAChR-G protein interactions in the basal ganglia may contribute to reduced signal transduction (ST). In addition, since decreased carbachol-stimulated low Km GTPase activity has also been observed in the aged rat; thus, investigations of the factors involved in decrements in signal transduction in the aged rat may be useful for understanding these alterations in aged humans or victims of AD.

Functional electrical stimulation treatment of postradiculopathy associated muscle weakness

Eighteen chronic pain patients (CPPs) with postradiculopathy-associated muscle weakness were entered into a nonrandomized functional electrical stimulation (FES) clinical treatment study to determine if FES can improve postradiculopathy associated muscle weakness. Because of the clinical nature of the unit, the CPPs could not be denied treatments other than FES. To control for these other treatments, the CPPs were used as their own controls with two control conditions, ie, where possible, the contralateral probable normal muscle was used as a control (control 1) and; in a subgroup of CPPs (n = 6), FES treatment was initially withheld to the probable weak muscle (control 2). Strength was measured as isometric maximum voluntary contraction (IMVC) and was used as the outcome treatment variable. IMVC was measured in both the probable weak and contralateral probable normal muscles at entrance into the Pain Center, at beginning of FES treatment, at completion of FES treatment, and for the control 2 condition at the end of the non-FES treatment period. Statistical analyses of the IMVC strength results using the two control conditions indicated (1) both the FES-treated and untreated muscles increased significantly in IMVC strength, (2) improvement in IMVC strength for FES-treated muscles was significantly greater than for probable normal FES-untreated muscles and, (3) improvement in IMVC strength in FES-treated muscles was significantly greater during the FES-treatment period than during the non-FES treatment period. FES treatment of postradiculopathy-associated muscle weakness in CPPs seems to increase the strength of the probable weak muscle above the increase in strength provided by other concurrent treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Measuring residual functional capacity in chronic low back pain patients based on the Dictionary of Occupational Titles

STUDY DESIGN

This study designed and tested a functional battery based on the Dictionary of Occupational Titles (DOT).

OBJECTIVES

Such a battery can be used to measure residual functional capacity (RFC) in chronic pain patients (CPP) and results can be matched against the demand minimum functional capacities (DMFC) of DOT jobs.

SUMMARY OF BACKGROUND DATA

Physicians have difficulty translating medical impairment into functional limitation and thereby establishing the RFC of CPPs.

METHODS

The DOT, a USA government publication, provides information about physical demands of every USA job according to 36 factors and subfactors. The authors defined and developed a functional battery based on these factors/subfactors. This battery was tested on 67 consecutive CPPs to determine the percentage of CPPs able to pass specific job factors and the full battery and return to some DOT job, and evaluated the effects of pain on battery performance. The data were factor analyzed.

RESULTS

The battery determined if CPPs could perform DOT job factors and had the necessary RFC to be placed in a DOT job. The vast majority of CPPs could not pass the full battery and the presence of pain and original job classification predicted whether a CPP could perform a job factor. Factor analyses grouped the factors into four independent categories supporting the design of the battery.

CONCLUSION

The battery can assess whether CPPs are able to return to work.

Changes in G protein-mediated signal transduction in aging and Alzheimer's disease

Previous reports have shown that there are age-related reductions in muscarinic receptor (mAChR) sensitivity to agonist stimulation. Our research has elucidated the mechanisms involved in this loss. These studies have shown that this decline is the result of decreases in mAChR concentration, reductions in the number of neuronal cells, and altered phosphoinositide (PI)-mediated signal transduction (ST). The decrements in PI-mediated ST are observed as a reduced ability of muscarinic (m) agonists to enhance K(+)-evoked release of DA (K+ ERDA) from striatal slices from old rats. Additional experiments indicated that the locus of the ST deficits appears to be at the mAChR-G protein interface, since attempts to bypass this interface reduced m-enhanced K+ ERDA deficits in the striata from old rats. Moreover, it appears that the ability of mAChR to decouple from their respective G proteins is reduced as a function of age, since carbachol-stimulated low KM GTPase activity was found to be reduced in hippocampal and striatal tissue obtained from old rats. Similar findings were observed in this parameter in AD hippocampus and basal ganglia. Further reductions were seen in carbachol-stimulated low KM GTPase as a function of the duration of the disease. Results are discussed in terms of structural membrane alterations in aging and disease that may lead to reductions in the efficacy of receptor-G protein coupling/uncoupling.

Functional capacity and residual functional capacity and their utility in measuring work capacity

OBJECTIVE

The pain physician is often asked to establish the medical impairment of the chronic pain patient (CPP) and from that determination ascertain the work capacity of the CPP. Functional capacity (FC) testing has recently been introduced as a more objective and accurate way of facilitating the determination of work capacity. However, there are conceptual problems with the measurement of FC. These will be reviewed and the relationship of FC to residual functional capacity (RFC) will be determined. Finally, a method for measuring RFC in a job-specific manner will be suggested.

DATA SOURCES

The literature in reference to the measurement of medical impairment, FC, and RFC was reviewed.

STUDY SELECTION

Studies appropriate to the objective of this review were selected for inclusion.

CONCLUSIONS

The FC and RFC are poorly defined. Lack of definition has interfered with design of appropriate test batteries specific to work capacity. To circumvent this problem a job-specific RFC measurement method is suggested. This method is based on the Dictionary of Occupational Titles.

Periodontal screening and recording: perceptions and effects on practice

Despite recent clinical innovations, there are considerable periodontal treatment needs for the general population. This study shows that dentists believe the new periodontal screening method will be useful in determining and providing treatment needs.

Opiate detoxification protocols. A clinical manual

The purpose of any opiate detoxification protocol is to minimize or eliminate the signs and symptoms associated with opiate withdrawal, thereby decreasing the chances of relapse to opiate dependence. In the last few years, because of the development of new medications such as clonidine, for the treatment of opiate withdrawal, a number of new protocols have been developed. Four different types of protocols are reviewed and outlined: methadone substitution/detoxification, codeine or other opiate substitution/detoxification, opiate of choice detoxification, and buprenorphine substitution/detoxification. In addition, six protocols utilizing clonidine are presented, including a protocol utilizing opiate antagonist precipitated withdrawal. Finally, two protocols that utilize naltrexone are outlined, and adjunct medications potentially useful in opiate detoxification are reviewed. Some suggestions for the treatment of drug-seeking behavior during detoxification and the advantages and disadvantages of the various protocols are summarized.

The prediction of return to the workplace after Multidisciplinary Pain Center treatment

The prediction of return to the workplace after Multidisciplinary Pain Center (MPC) treatment has become a major research area. To delineate the variables that predict this outcome, the authors reviewed 164 multidisciplinary variables studies. Of these, 79 addressed work as an outcome variable. Twenty-six studies attempted to identify patient variables predicting return to the workplace. These latter studies were critically inspected for eight methodological criteria: pain location, follow-up time interval, response percentage and follow-up method, return to work subcategorization, vocational movement, univariate vs. multivariate statistics, multi-colinearity and variance, and statistical treatment of dropouts. In addition, other disability studies besides those in the chronic pain area were reviewed for return to the workplace predictor variables. Of these 26 studies, only a few appeared to satisfy the criteria examined. In addition, many studies were in conflict with one another on whether a variable was predictive. The review of the nonchronic pain/disability prediction literature yielded a large number of potential predictors that related to the work area. It is unclear which variables or set of variables predict return to the workplace after MPC treatment. Chronic pain studies may be neglecting the work area as an important source of return to the workplace predictor variables.

The effects of aging on muscarinic receptor/G-protein coupling in the rat hippocampus and striatum

In the striatum and hippocampus, there is a loss of sensitivity to muscarinic agonists with age which has been traced to events early in the signal transduction pathway. Our laboratory has therefore focussed on investigations at this level. The current experiments investigate the effects of age on G-protein/receptor interactions by using competitive binding assays to measure the ability of GppNHp to decrease the proportion of receptors bound to G-proteins in the absence and the presence of added Mg2+. L-[3H]Quinuclidinyl benzilate was used as a nonselective ligand and [3H]pirenzepine as an M1 selective ligand. We find that: (1) muscarinic receptors and G-proteins in the striatum appear to become loosely coupled with age, with no change in Mg2+ sensitivity. (2) M1-receptor/G-protein complexes in the hippocampus display increased sensitivity to the presence of Mg2+ with age, with those from old but not young tissue requiring added Mg2+ in order to uncouple. This effect, however, may not be M1 specific.

Multicenter comparison of once- and twice-daily isradipine to hydrochlorothiazide for the treatment of hypertension in elderly patients

After 8 weeks of isradipine, a twice-a-day dihydropyridine calcium channel blocker, 49% of elderly patients showed a complete response (sitting diastolic blood pressure less than or equal to 85 mm Hg) and 36% showed a partial response (sitting diastolic blood pressure decrease greater than or equal to 10 mm Hg) for an 85% total response rate. Hydrochlorothiazide gave a complete response in 36% of the patients and a partial response in 33%, for a 69% total response rate (p less than 0.0046). Because elderly subjects have reduced clearance for many drugs, we determined how those who responded to twice-a-day administration would respond to once-a-day administration. After 4 weeks of isradipine administered once a day, 54% of the patients showed a complete or partial response, whereas 38% of the patients who were changed to placebo showed a response. In contrast, 82% of patients receiving hydrochlorothiazide once a day showed a response, whereas 60% of patients who were changed to placebo showed a response. These data indicate that the standard formulation of isradipine was not effective when administered once a day.

One-year follow-up of infants with abstinence-associated seizures

Fourteen infants with neonatal abstinence-associated seizures were assessed neurodevelopmentally during the first year of life. Despite abnormal neurologic examination results in eight of 12 infants at 2 to 4 months of age, nine of 12 infants had normal neurologic examination results at follow-up (two infants were unavailable for follow-up; one infant died of acquired immunodeficiency syndrome). Nine neonatal electroencephalograms were abnormal; seven of eight of these abnormal tracings normalized during the follow-up period. Bayley developmental scores remained normal during the first year of life and did not differ from either passively addicted infants without seizures or from published population norms. This short-term favorable prognosis for abstinence-associated seizures differs from that associated with neonatal seizures due to other causes. This observed improvement in neurologic function may be based on replenishment of neurotransmitters following transient depletion in the neonatal period.