Shared medical appointments for patients with a nondiabetic physical chronic illness: A systematic review

OBJECTIVES

Shared medical appointments are group appointments, with an optional individual consultation, for patients diagnosed with chronic illnesses. Shared medical appointments improve diabetes management, but little is known about their use for other illnesses. The objective was to determine the effect that shared medical appointments have on patients with a physical chronic illness, healthcare providers, and the healthcare system.

METHODS

A systematic review was conducted searching databases from January 1970 to September 2016. Eligible trials evaluated shared medical appointments for patients with a homogeneous chronic illness, excluding diabetes and mental illness. Screening, data extraction, and risk of bias were conducted independently by two authors. Analysis was descriptive.

RESULTS

Of 2364 citations, nine randomized trials were included. Shared medical appointments were evaluated for cardiovascular illnesses (four studies), breast cancer, chronic kidney disease, Parkinson's disease, stress urinary incontinence, and carpal tunnel syndrome. Compared to usual care, no negative effects on patient quality of life, knowledge and satisfaction were reported. One study reported no difference in healthcare provider satisfaction. Another study showed fewer hospital admissions for patients who attended shared medical appointments.

DISCUSSION

Few rigorous studies evaluated the use of shared medical appointments for chronic illnesses. Overall, there appears to be no patient harms. Further studies should include more objective outcomes and larger sample sizes.

Usp9X Regulates Cell Death in Malignant Peripheral Nerve Sheath Tumors

Malignant peripheral nerve sheath tumors (MPNSTs) are the leading cause of death in neurofibromatosis type 1 (NF1) patients. Current treatment modalities have been largely unsuccessful in improving MPNST patient survival, making the identification of new therapeutic targets urgent. In this study, we found that interference with Usp9X, a deubiquitinating enzyme which is overexpressed in nervous system tumors, or Mcl-1, an anti-apoptotic member of the Bcl-2 family whose degradation is regulated by Usp9X, causes rapid death in human MPNST cell lines. Although both Usp9X and Mcl-1 knockdown elicited some features of apoptosis, broad spectrum caspase inhibition was ineffective in preventing knockdown-induced MPNST cell death suggesting that caspase-independent death pathways were also activated. Ultrastructural examination of MPNST cells following either Usp9X interference or pharmacological inhibition showed extensive cytoplasmic vacuolization and swelling of endoplasmic reticulum (ER) and mitochondria most consistent with paraptotic cell death. Finally, the Usp9X pharmacological inhibitor WP1130 significantly reduced human MPNST growth and induced tumor cell death in an in vivo xenograft model. In total, these findings indicate that Usp9X and Mcl-1 play significant roles in maintaining human MPNST cell viability and that pharmacological inhibition of Usp9X deubiquitinase activity could be a therapeutic target for MPNST treatment.

Symptom practice guide for telephone assessment of patients with cancer treatment-related cardiotoxic dyspnea: Adaptation and evaluation of acceptability

BACKGROUND

Patients with cancer treatment-related cardiotoxicity, which may manifest as heart failure (HF), can present with dyspnea. Nurses frequently assess, triage and offer self-care strategies to patients experiencing dyspnea in both the cardiology and oncology settings. However, there are no known tools available for nurses to manage patients in the setting of cancer treatment-related cardiotoxicity. The objective of this study was to adapt and evaluate the acceptability of an evidence-informed symptom practice guide (SPG) for use by nurses over the telephone for the assessment, triage, and management of patients experiencing dyspnea due to cancer treatment-related cardiotoxicity.

METHODS

The CAN-IMPLEMENT© methodology guided this descriptive study. A systematic search was conducted in four databases to identify cardio-oncology and HF guidelines and systematic reviews. Screening was conducted by two reviewers, with data extracted into a recommendation matrix from eligible guidelines and systematic reviews on: assessment criteria, medications, and/or self-care strategies to manage dyspnea. Healthcare professionals with an expertise in oncology and/or cardiology were recruited using purposeful and snowball sampling. Evaluation of acceptability of the adapted SPG was gathered through semi-structured interviews and a survey with open- and closed-ended questions. Quantitative findings and participant feedback from the interviews and the open-ended survey questions were analyzed descriptively.

RESULTS

Of 490 citations, seven HF guidelines were identified. Evidence from these guidelines was added to the original SPG. Eleven healthcare professionals completed the interview and acceptability survey. The adapted SPG was iteratively revised three times during the interviews. The original SPG was adaptable, and participants indicated the adapted SPG was comprehensive, easy to follow, and would be useful in clinical practice.

CONCLUSIONS

This study highlights the lack of knowledge tools and available clinical practice guidelines to guide healthcare professionals to assess, triage and/or offer self-care strategies to patients with cancer treatment-related cardiotoxic dyspnea. Moreover, most nurses require assistance to differentiate among the various causes of dyspnea from oncology treatment in order to triage severity appropriately. Further research should focus on evaluating the validity of the adapted SPG in clinical practice.

Assessment of oncolytic HSV efficacy following increased entry-receptor expression in malignant peripheral nerve sheath tumor cell lines

Limited expression and distribution of nectin-1, the major herpes simplex virus (HSV) type-1 entry-receptor, within tumors has been proposed as an impediment to oncolytic HSV (oHSV) therapy. To determine whether resistance to oHSVs in malignant peripheral nerve sheath tumors (MPNSTs) was explained by this hypothesis, nectin-1 expression and oHSV viral yields were assessed in a panel of MPNST cell lines using γ134.5-attenuated (Δγ134.5) oHSVs and a γ134.5 wild-type (wt) virus for comparison. Although there was a correlation between nectin-1 levels and viral yields with the wt virus (R=0.75, P =0.03), there was no correlation for Δγ134.5 viruses (G207, R7020 or C101) and a modest trend for the second-generation oHSV C134 (R=0.62, P=0.10). Nectin-1 overexpression in resistant MPNST cell lines did not improve Δγ134.5 oHSV output. While multistep replication assays showed that nectin-1 overexpression improved Δγ134.5 oHSV cell-to-cell spread, it did not confer a sensitive phenotype to resistant cells. Finally, oHSV yields were not improved with increased nectin-1 in vivo. We conclude that nectin-1 expression is not the primary obstacle of productive infection for Δγ134.5 oHSVs in MPNST cell lines. In contrast, viruses that are competent in their ability to counter the antiviral response may derive benefit with higher nectin-1 expression.

Knockout of plasminogen activator inhibitor 1 gene reduces amyloid beta peptide burden in a mouse model of Alzheimer's disease

Accumulation of amyloid beta peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD); the underlying mechanism, however, is not well understood. In this study, we show that expression of plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), increases with age in the brain of wild type and Aβ precursor protein-presenilin 1 (APP/PS1) transgenic mice as well as in AD patients. Most importantly, we show that knocking out the PAI-1 gene dramatically reduces Aβ burden in the brain of APP/PS1 mice but has no effect on the levels of full-length APP, alpha or beta C-terminal fragments. Furthermore, we show that knocking out the PAI-1 gene leads to increases in the activities of tPA and plasmin, and the plasmin activity inversely correlates with the amounts of SDS insoluble Aβ40 and Aβ42. Together, these data suggest that increased PAI-1 expression/activity contributes importantly to Aβ accumulation during aging and in AD probably by inhibiting plasminogen activation and thus Aβ degradation.

Phylogenetic and functional biomakers as indicators of bacterial community responses to mixed-waste contamination

Few studies have demonstrated changes in community structure along a contaminant plume in terms of phylogenetic, functional, and geochemical changes, and such studies are essential to understand how a microbial ecosystem responds to perturbations. Clonal libraries of multiple genes (SSU rDNA, nirK, nirS, amoA, pmoA, and dsrAB) were analyzed from groundwater samples (n = 6) that varied in contaminant levels, and 107 geochemical parameters were measured. Principal components analyses (PCA) were used to compare the relationships among the sites with respect to the biomarker (n = 785 for all sequences) distributions and the geochemical variables. A major portion of the geochemical variance measured among the samples could be accounted for by tetrachloroethene, 99Tc, No3, SO4, Al, and Th. The PCA based on the distribution of unique biomarkers resulted in different groupings compared to the geochemical analysis, but when the SSU rRNA gene libraries were directly compared (deltaC(xy) values) the sites were clustered in a similar fashion compared to geochemical measures. The PCA based upon functional gene distributions each predicted different relationships among the sites, and comparisons of Euclidean distances based upon diversity indices for all functional genes (n = 432) grouped the sites by extreme or intermediate contaminant levels. The data suggested that the sites with low and high perturbations were functionally more similar than sites with intermediate conditions, and perhaps captured the overall community structure better than a single phylogenetic biomarker. Moreover, even though the background site was phylogenetically and geochemically distinct from the acidic sites, the extreme conditions of the acidic samples might be more analogous to the limiting nutrient conditions of the background site. An understanding of microbial community-level responses within an ecological framework would provide better insight for restoration strategies at contaminated field sites.

Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor

High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n = 500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.

Neuregulin-1β modulates in vivo entorhinal–hippocampal synaptic transmission in adult rats

Neuregulin-1 (NRG-1) proteins and their erbB receptors are essential for neuronal development during embryogenesis and may contribute importantly to neuronal function in the adult brain. This study tests the hypothesis that NRG-1beta acts as a modulator of synaptic activity in the adult brain, specifically at hippocampal formation synapses. Adult, male Sprague-Dawley rats were anesthetized and a recording electrode with an attached stainless steel microinjector was stereotaxically positioned to record field potentials (fEPSP) in either the dentate gyrus or the cornu ammonis (CA) 1 field of the hippocampus. The entorhinal cortex was continuously stimulated via a paired stainless steel electrode. Microinjection of NRG-1beta significantly increased the slope of the fEPSP in the dentate gyrus in a dose-dependent manner. Compared with a low dose (20 nM), a high dose (100 nM) of NRG-1beta induced a shorter latency response that was of greater magnitude. Responses to NRG-1beta were abolished by pretreatment with a selective, reversible erbB tyrosine kinase inhibitor, PD158780 (100 microM). Further, PD158780 (100 microM) itself significantly decreased the entorhinal-dentate fESPS slope by about 15%. Neither equimolar (100 nM) nor hypermolar (100 microM) sucrose or heat-inactivated NRG-1beta (100 nM) significantly altered the entorhinal-dentate fEPSP slope. In contrast to its effect at the entorhinal-dentate synapse, NRG-1beta (100 nM) depressed, and PD158780 potentiated entorhinal-CA1 synaptic transmission. Thus, in adult rats NRG-1beta potentiates transmission at the entorhinal-dentate synapse but suppresses transmission at the entorhinal-CA1 synapse. These observations indicate that NRG-1 is not only a developmental growth factor, but also modifies synaptic transmission in adult rat brain.

Targeting and functional role of N-RAP, a nebulin-related LIM protein, during myofibril assembly in cultured chick cardiomyocytes

Targeting and functional effects of N-RAP domains were studied by expression as GFP-tagged fusion proteins in cultured embryonic chick cardiomyocytes. GFP-tagged N-RAP was targeted to myofibril precursors, myofibril ends and cell contacts, expression patterns that are similar to endogenous N-RAP. The GFP-tagged N-RAP LIM domain (GFP-N-RAP-LIM) was targeted to the membrane in cells with myofibril precursors and cell-cell contacts. The GFP-tagged super repeats (N-RAP-SR) and the GFP-tagged domain normally found in between the super repeats and the LIM domain (N-RAP-IB) were each observed at sites of myofibril assembly, incorporating into myofibril precursors in a manner similar to full length N-RAP. However, unlike full-length N-RAP, N-RAP-SR and N-RAP-IB were also found in mature myofibrils, associating with the sarcomeric actin filaments and the Z-lines, respectively. N-RAP-IB was also colocalized with α-actinin at cell contacts. Each of the N-RAP constructs could inhibit the formation of mature myofibrils in cultured cardiomyocytes, with the effects of N-RAP-SR and N-RAP-IB depending on the time of transfection. The results show that each region of N-RAP is crucial for myofibril assembly. Combining the targeting and functional effects of N-RAP domains with information in the literature, we propose a new model for initiation of myofibrillogenesis.

ErbB transmembrane tyrosine kinase receptors are differentially expressed throughout the adult rat central nervous system

The neuregulin (NRG) family of growth and differentiation factors and their erbB receptors contribute importantly to the development of the nervous system, but their distribution and function in the adult brain are poorly understood. The present study showed that erbB2, erbB3, and erbB4 transcripts and protein are distributed throughout all areas of adult rat brain. These three receptors were differentially expressed in neurons and glia. Some neurons expressed only a subset of erbB kinases, whereas other neurons expressed all three erbB receptors but sequestered each of these polypeptides into distinct cellular compartments. In synapse-rich regions, erbB immunoreactivity appeared as punctate-, axon-, and/or dendrite-associated staining, suggesting that NRGs are involved in the formation and maintenance of synapses in adult brain. ErbB labeling also was present in neuronal soma, indicating that NRGs act at sites in addition to the synapse. Glia in adult brain also differentially expressed erbB3 and erbB4. Approximately half of the erbB3 labeling in white matter was associated with S100beta+/glial fibrillary acidic protein negative macroglia (i.e., oligodendrocytes or glial fibrillary acidic protein negative astrocytes). In contrast, macroglia in gray matter did not express erbB3. The remaining erbB3 immunoreactivity in white matter and erbB4 glial staining seemed to be associated with microglia. These results showed that erbB receptors are expressed widely in adult rat brain and that each erbB receptor subtype has a distinct distribution. The differential distributions of erbB receptors in neurons and glia and the known functional differences between these kinases suggest that NRGs have distinct effects on these cells. The continued expression of NRGs and their erbB receptors in mature brain also implies that these molecules perform important functions in the brain throughout life.

Attenuation of experimental autoimmune demyelination in complement-deficient mice

The exact mechanisms leading to CNS inflammation and myelin destruction in multiple sclerosis and in its animal model, experimental allergic encephalomyelitis (EAE) remain equivocal. In both multiple sclerosis and EAE, complement activation is thought to play a pivotal role by recruiting inflammatory cells, increasing myelin phagocytosis by macrophages, and exerting direct cytotoxic effects through the deposition of the membrane attack complex on oligodendrocytes. Despite this assumption, attempts to evaluate complement's contribution to autoimmune demyelination in vivo have been limited by the lack of nontoxic and/or nonimmunogenic complement inhibitors. In this report, we used mice deficient in either C3 or factor B to clarify the role of the complement system in an Ab-independent model of EAE. Both types of complement-deficient mice presented with a markedly reduced disease severity. Although induction of EAE led to inflammatory changes in the meninges and perivascular spaces of both wild-type and complement-deficient animals, in both C3(-/-) and factor B(-/-) mice there was little infiltration of the parenchyma by macrophages and T cells. In addition, compared with their wild-type littermates, the CNS of both C3(-/-) and factor B(-/-) mice induced for EAE are protected from demyelination. These results suggest that complement might be a target for the therapeutic treatment of inflammatory demyelinating diseases of the CNS.

Glutamate transporter EAAT2 splice variants occur not only in ALS, but also in AD and controls

OBJECTIVE

To ascertain the specificity of alternatively spliced mRNA variants of the astroglial glutamate transporter EAAT2 for ALS.

BACKGROUND

An important hypothesis for ALS pathogenesis is that motor neuron injury may result from chronically elevated glutamate levels in the CNS. Supporting this idea are reports of decreased glutamate transport in ALS. This in turn has recently been suggested to be due to the presence of aberrant mRNA splice variants for EAAT2 in ALS.

METHODS

Postmortem human brain tissue was obtained from different brain regions of patients with ALS, normal controls (NC), and patients with AD and Lewy body dementia (LB)-neurodegenerative diseases in which motor neurons are unaffected. Brain RNA was analyzed for EAAT2 isoforms using reverse transcription PCR and cDNA cloning/sequencing methods.

RESULTS

Splice variants lacking exons 7 or 9 were present in ALS brain, as previously reported, but were also present in brains from NC, AD, and LB patients. PCR product sequence analyses from non-ALS brain show variant splicing identical to that reported for ALS. Quantitative PCR analysis shows that these isoforms may be somewhat more abundant in ALS than AD, LB, and NC brains.

CONCLUSIONS

EAAT2 mRNA splice variants are found in the brains of NC and AD patients, as in ALS. The authors cannot exclude the possibility that quantitative changes in variant EAAT2 isoforms might relate directly, or indirectly, to ALS pathology. However, the qualitative presence of these "abnormal" EAAT2 splice variants does not appear to be sufficient to explain motor neuron degeneration in ALS.

Myofibrillogenesis and formation of cell contacts mediate the localization of N-RAP in cultured chick cardiomyocytes

The expression of N-RAP was investigated in immuofluorescently stained embryonic chick cardiomyocyte cultures. After 1 day in culture, the cardiomyocytes were spherical and N-RAP, titin, alpha-actinin, and vinculin were all diffusely distributed. As the cardiomyocytes spread and formed myofibrils and cell contacts, N-RAP became localized to distinct areas in the cells. During myofibrillogenesis, N-RAP was found concentrated in premyofibrils. As the premyofibrils transformed into bundles of mature myofibrils, N-RAP became concentrated at the longitundal ends of the cells, and was not found in the mature sarcomeres. At sites of cell-cell contacts, N-RAP was localized to the cell junction even in cells without any significant myofibril formation. As the cell-cell contacts became more extensive and formed structures resembling the intercalated disks found in hearts, N-RAP became even more specifically concentrated at these junctions. The results show that myofibrillogenesis and cell contact formation can each independently target N-RAP to the longitudinal ends of cardiomyocytes.

Expression of JE (monocyte chemoattractant protein-1) is induced by sciatic axotomy in wild type rodents but not in C57BL/Wld(s) mice

Recruitment of hematogenous myelomonocytic cells into injured peripheral nerve is essential for axonal regeneration. The monocyte chemoattractant protein-1 (JE) and melanoma growth stimulatory activity/gro (KC) "immediate early" gene products may be important in this process as these proteins are potent chemoattractants for macrophages and neutrophils, respectively. To test this hypothesis, we examined JE and KC activation in rat sciatic nerve 0-30 days after surgical transection. RT-PCR and in situ hybridization analyses of JE and KC expression demonstrates these mRNAs are present in injured nerve, first being expressed by a cellular subpopulation within the zone of trauma by 1.5 hours after injury. By 16 hours posttransection a subpopulation of JE-positive endoneurial cells is found in the proximal stump and throughout the distal nerve segment, with maximal mRNA accumulation occurring 1 day after injury and expression persisting to 18 days postaxotomy, a period preceding and coincident with macrophage infiltration. In contrast, by 3 days postaxotomy KC expression is markedly diminished, consistent with the limited neutrophilic response to nerve injury. JE expression was also examined in C57BL/Wld(s) mice, which have delayed Wallerian degeneration associated with a failure of macrophage recruitment, and their parental C57BL/6J strain. Although JE mRNA is inducible in sciatic nerve from C57BL/6J mice, these transcripts are undetectable in injured nerve from C57BL/Wld(s) mice. Our findings suggest that activation of the JE locus is at least partially responsible for macrophage invasion of injured peripheral nerve. Furthermore, defective postaxotomy macrophage recruitment in C57BL/Wld(s) mice may involve a failure of JE induction.

Neurotrophin sensitivity of prevertebral and paravertebral rat sympathetic autonomic ganglia

Prevertebral and paravertebral sympathetic autonomic ganglia respond differently to a large number of experimental and clinical insults. The selective involvement of subpopulations of sympathetic neurons may reflect differences in their response to neurotrophic substances. To test this hypothesis, we investigated the response of prevertebral and paravertebral rat sympathetic ganglia to selected neurotrophic substances in vivo and in vitro and identified the ganglionic distribution of neurons expressing high affinity neurotrophin receptor mRNAs. Dissociated cultures of embryonic prevertebral and paravertebral ganglionic neurons showed comparable responses to NGF deprivation and only small differences in their response to rescue with other trophic substances. In situ hybridization studies of adult rat sympathetic ganglia using probes specific for the high-affinity neurotrophin receptor transcripts trks A, B, and C demonstrated that neurons in both prevertebral and paravertebral sympathetic ganglia express predominantly trkA receptors in vivo. In addition, increased tyrosine hydroxylase (TOH) activity was induced only by doses of neurotrophic substances that activate trkA and showed only small differences between neonatal prevertebral and paravertebral ganglia. Although small differences in the sensitivity of pre- and paravertebral sympathetic neurons to various neurotrophins have been identified in our studies, they are unlikely, in isolation, to explain major differences in the sensitivity of these ganglia to neuropathologic processes.

Clear cell neoplasms and pseudoneoplastic lesions of the central nervous system

Mass lesions of the central nervous system (CNS) that may assume a clear cell appearance are diverse in nature. Primary conditions in this category include oligodendroglioma, hemangioblastoma, germinoma (seminoma), clear cell and chordoid meningioma, pleomorphic xanthoastrocytoma, and lipid-rich glioblastoma. These proliferations usually can be identified by attention to clinical presentation, topographic location, radiographic details, and histological nuances. Occasionally, however, electron microscopy or immunohistological analysis may be necessary. A recommended panel of reagents for the evaluation of clear cell primary CNS lesions include antibodies to glial fibrillary acidic proteins, S-100 protein, epithelial membrane antigen, vimentin, keratins, placental-like alkaline phosphatase, and synaptophysin. This article reviews the salient clinicopathologic attributes of such proliferations, elaborates a practical approach to their diagnosis, and discusses important differential diagnostic considerations. The latter include malformative lesions, infarcts, inflammatory conditions, and secondary lymphomas, carcinomas, and melanomas.

Decay of calcium transients after electrical stimulation in rat fast- and slow-twitch skeletal muscle fibres

1. Calcium transients were calculated from fura-2 fluorescence signals (corrected for kinetic delays in the Ca(2+)-fura-2 reaction) from single rat skeletal muscle fibres, either fully dissociated from the fast-twitch flexor digitorum brevis (FDB) muscle or in small bundles from the slow-twitch soleus muscle. Fibres or bundles were embedded in agarose gel to inhibit movement and stimulated by single or trains of 1-2 ms electrical pulses (100 Hz, 2-400 ms train duration). 2. The rate constant of decay of [Ca2+] determined from single-exponential fits to the final decay phase of [Ca2+] after a single action potential was considerably faster in FDB fibres than in soleus fibres. As the stimulation duration increased, the rate constant of [Ca2+] decay decreased for both the FDB and soleus fibres, but the effect was greater in FDB than in soleus fibres. 3. Using the magnitude of the decline in the rate constant of [Ca2+] decay with increasing stimulation duration as an index of relative contribution of the saturable Ca2+ binding sites on parvalbumin, subpopulations termed 'high', 'medium' and 'low', referring to estimated parvalbumin content, were determined within each group of FDB and soleus fibres. In fibres assigned to the 'high' and 'medium' groups, parvalbumin was the major contributor (50-73%) to the [Ca2+] decay rate constant after a single action potential. In fibres in the 'low' group, parvalbumin contributed only 0-28% to the rate constant of [Ca2+] decay. 4. Fluorescence recordings using mag-fura-2, a lower-affinity Ca2+ indicator expected to be in equilibrium with myoplasmic Ca2+, gave similar values for both the [Ca2+] decay rate constant after a single action potential and the decrease in this rate constant with increased stimulation duration, as found for the fura-2 [Ca2+] transients from FDB and soleus fibres. Thus, the observed differences in decay rate of Ca2+ were not introduced by kinetic correction of the fura-2 recordings, but are attributed to differences in the Ca2+ binding and transport properties of fast- and slow-twitch mammalian fibres.

Calcium transients and calcium homeostasis in adult mouse fast-twitch skeletal muscle fibers in culture

Skeletal muscle fibers enzymatically dissociated from adult mouse flexor digitorum brevis muscles were maintained in culture for up to 8 days. After various times in culture, fibers were loaded with fura 2, and Ca2+ transients for trains of 1, 5, and 10 action potentials (100 Hz) triggered by external electrical stimulation were calculated from fluorescence ratio records corrected for noninstantaneous reaction of fura 2 with Ca2+. The decay rate constants of Ca2+ transients decreased with increasing stimulation duration, indicating a slowing of the Ca(2+)-removal properties with increased stimulation duration. After 6 days in culture, Ca2+ decay rate constants decreased dramatically for all stimulation durations and the differences in decay rate constants among 1, 5, and 10 pulses became smaller. Intracellular parvalbumin content measured by single-fiber immunofluorescence decreased with time in culture in parallel with the decrease in the decay rate constant of Ca2+ transients. Our results suggest that there is a correlation between parvalbumin content and the decay rate constant of the Ca2+ transient.

Expression of neuregulins and their putative receptors, ErbB2 and ErbB3, is induced during Wallerian degeneration

Schwann cell dedifferentiation and proliferation is a prerequisite to axonal regeneration in the injured peripheral nervous system. The neuregulin (NRG) family of growth and differentiation factors may play a particularly important role in this process, because these axon-associated molecules are potent Schwann cell mitogens and differentiation factors in vitro. We have examined Schwann cell DNA synthesis and the expression of NRGs and their receptors, the erbB membrane tyrosine kinases, in rat sciatic nerve, sensory ganglia, and spinal cord 0-30 d postaxotomy. Analysis of NRG cDNAs from these tissues revealed several novel splice variants and showed that cells endogenous to injured nerve express NRG mRNAs. A selective induction of mRNAs encoding the glial growth factor (GGF) subfamily of NRGs occurs in nerve beginning 3 d postaxotomy and thus coincides with the onset of Schwann cell DNA synthesis. In later stages of Wallerian degeneration, however, Schwann cell mitogenesis markedly decreases, whereas elevated GGF expression persists. Of the four known erbB kinases, Schwann cells express both erbB2 and erbB3 receptors over the entire interval studied. Expression of erbB2 and erbB3 is coordinately induced in response to axotomy, indicating that Schwann cell responses to NRGs may be modulated by changes in receptor density. Neuregulin (including transmembrane precursors) and erbB protein are associated with Schwann cells postaxotomy. Thus, in contrast to the concept of NRGs as axon-associated mitogens, our findings suggest that NRGs produced by Schwann cells themselves may be partially responsible for Schwann cell proliferation during Wallerian degeneration, probably acting via autocrine or paracrine mechanisms.

Neuropathy of metachromatic leukodystrophy: improvement with immunomodulation

A 4-year-old child with metachromatic leukodystrophy was initially diagnosed with chronic immune demyelinating polyneuropathy and treated with immunosuppressive therapy. Physical examination revealed diffuse, distal > proximal weakness and areflexia. Electro-diagnostic studies revealed nerve conduction velocities that were slowed to variable degrees in different nerves. In the 18 months after institution of immunomodulating therapy, she had functionally significant improvement and a quantitative increase in her strength. Treatment was discontinued at age 6 years when the patient developed urinary incontinence, followed by loss of motor and cognitive skills. We conclude that immunomodulation early in the course of metachromatic leukodystrophy presenting as a neuropathy may result in temporary functional improvement. Whether the immunomodulation altered the disease progression or had direct effects on the function of the dysmyelinated axons is not known.

Calcium transients in intact rat skeletal muscle fibers in agarose gel

Intact single fibers enzymatically dissociated from rat flexor digitorum brevis muscle were suspended in 0.5% low-melting-temperature agarose gel to minimize fiber movement during action potentials or trains of action potentials. Resting Ca2+ concentration ([Ca2+]) and changes in [Ca2+] were monitored using the fluorescent calcium indicator fura 2. The time course and waveform of [Ca2+] transients during an action potential or trains of action potentials in fibers in agarose were calculated using kinetic parameters previously determined to correct for the calcium-fura 2 kinetic delay. Half times of the calculated calcium transients for single action potentials were 30-fold briefer than the original fura 2 signals. To confirm the time course and waveform of the calculated calcium transients, changes in [Ca2+] were monitored using the more rapidly equilibrating calcium indicator mag-fura 2. [Ca2+] transients for fibers containing fura 2 had very similar time courses and waveforms as mag-fura 2 signals from other fibers, indicating that the corrections for the calcium-fura 2 kinetic delay were accurate. The advantages of the agarose gel suspension are discussed.

Elements in the 5' flanking sequences of the mouse low-affinity NGF receptor gene direct appropriate CNS, but not PNS, expression in transgenic mice

We have initiated a characterization of the cis-acting regulatory elements of the murine low-affinity NGF receptor (p75NGFR) gene. Despite studies in cultured cells that suggest the p75NGFR promoter is constitutive, a detailed analysis of this promoter in five lines of transgenic mice demonstrated a high degree of cell-type specificity: 8.4 kb of 5' flanking sequence directs expression of a lacZ reporter to retinal and CNS neurons normally expressing p75NGFR. A transgene with 470 bp of 5' flanking sequence is also expressed in the CNS, but its regulation is aberrant, with a loss of basal forebrain expression. In non-neural tissues, both transgenes were expressed only in the testis, kidney, anterior pituitary, and pancreatic islets; with the exception of the renal pattern of expression, transgene activity was confined to appropriate cells within these tissues. In contrast, although expression of both transgenes was prominent in adrenal medulla and gastrointestinal myenteric neurons, neither construct was active in several sensory or sympathetic ganglia that strongly express the endogenous p75NGFR gene, indicating that genetic elements necessary for expression in these neurons are not present in these promoter sequences. In addition, neither transgene was activated in Schwann cells during Wallerian degeneration of sciatic nerve. We conclude that regulation of the p75NGFR gene is complex, with the first 470 bp of 5' flanking sequence sufficient for expression in enteric and CNS neurons and additional elements within the first 8.4 kb of 5' flanking sequence required for restriction to appropriate CNS neurons. Further regulatory elements are possibly required for expression in at least some sensory and sympathetic neurons in the PNS and in Schwann cells. To identify potential regulatory elements in the 470 bp of 5' flanking sequence from the smaller transgene, we compared the sequences of equivalent regions from the mouse, rat, and human p75NGFR genes. This "phylogenetic footprint" identified conserved motifs potentially important for the regulation of this gene in the CNS.

Neurotrophin receptor genes are expressed in distinct patterns in developing dorsal root ganglia

All members of the neurotrophin family of neuronal growth factors promote survival and neurite outgrowth of dorsal root ganglion (DRG) neurons in vitro. The trk family of protooncogenes encodes receptors that are now thought to mediate the biological effects of neurotrophins. In order to learn more about the dependence of DRG neurons on neurotrophins in vivo, we have studied mRNA expression of members of the trk family in developing DRGs in embryonic and postnatal rats. We show here that neurotrophin receptors are expressed in thoracic and lumbar DRGs by embryonic day 13 (E13), which is only 24-48 hr after neurogenesis begins in these ganglia. Distinct patterns of expression of trkA, trkB, and trkC are readily apparent by E15. At this age, 40% of thoracic DRG neurons express trkA. In contrast, trkB and trkC are expressed by only 6% and 8%, respectively, of thoracic DRG neurons. These percentages change little between E15 and postnatal day 1. Although absolute numbers of DRG neurons expressing neurotrophin receptors are greater in lumbar than in thoracic ganglia, the ratios of DRG neurons expressing different members of the trk family are similar in the two regions. The different trks are expressed by distinct populations of DRG neurons from E15 onward. trkA is expressed predominantly by small neurons with darkly staining cytoplasm. trkB and trkC are expressed by large, lightly staining neurons. Size-frequency histograms show that trkA is expressed by neurons of variable sizes, but particularly by neurons at the smallest end of the spectrum. In contrast, trkC is expressed predominantly by large DRG neurons, including those with the largest soma areas. trkB is expressed by DRG neurons of intermediate size. Our results show that a majority of DRG neurons express mRNA for at least one member of the trk protooncogene family. Furthermore, trk expression occurs in a time frame consistent with the idea that trks mediate responses of DRG neurons to neurotrophins that are synthesized in both the periphery and spinal cord at early developmental stages. Finally, different populations of DRG neurons express different trks. We hypothesize that DRG neurons subserving different functions express different trks, and that trk expression of a particular class of DRG neurons determines its neurotrophin dependence during development.

Developmentally regulated expression of pleiotrophin, a novel heparin binding growth factor, in the nervous system of the rat

Pleiotrophin (PTN) is a newly identified heparin-binding growth factor which is closely related to the retinoic acid-inducible MK protein. PTN is expressed at high levels in perinatal brain and promotes neurite outgrowth from embryonic brain neurons and mitogenesis in fibroblasts, suggesting that it may play an important role in the development of the nervous system. We have used in situ hybridization to examine PTN expression in the developing and adult rat nervous systems. During embryogenesis, PTN mRNA is primarily expressed by neuroglial progenitor cells in the subependymal layer of the central nervous system (CNS), whereas during the perinatal period high levels of PTN transcripts are found in neurons as well as glial elements (astrocytes and oligodendrocytes). In the adult brain, PTN expression is markedly decreased relative to early postnatal brain and, in contrast to the neuronal and glial expression observed in young animals, is confined to specific neuronal subpopulations (especially hippocampal CA1-3 regions, cerebral cortex laminae II-IV). PTN is also expressed in the developing spinal cord and eye. In the peripheral nervous system (PNS), PTN mRNA is present in ganglionic neurons during embryogenesis. In adult ganglia, however, PTN expression becomes localized to the satellite cells of the ganglia. The developmental pattern of PTN expression in the CNS and the 'switch' in expression from neurons to satellite cells in the PNS suggests that it has important functions not only in the developing nervous system, but also in the adult CNS and PNS and that the functions performed by this growth factor change during ontogeny. We have also found that levels of PTN mRNA are dramatically but transiently elevated in neurons of the hippocampus, piriform cortex and parietal cortex following a chemically induced seizure, indicating that neuronal PTN mRNA expression is increased by intense physiological stimuli and may play a role in the response to these stimuli.

Dorsal root ganglion neurons expressing trk are selectively sensitive to NGF deprivation in utero

In utero immune deprivation of the neurotrophic molecule nerve growth factor (NGF) results in the death of most, but not all, mammalian dorsal root ganglion (DRG) neurons. The recent identification of trk, trkB, and trkC as the putative high affinity receptors for NGF, brain-derived neurotrophic factor, and neurotrophin-3, respectively, has allowed an examination of whether their expression by DRG neurons correlates with differential sensitivity to immune deprivation of NGF. In situ hybridization demonstrates that virtually all neurons expressing trk are lost during in utero NGF deprivation. Most, if not all, neurons expressing trkB and trkC survive this treatment. In contrast, the low affinity NGF receptor, p75NGFR, is expressed in both NGF deprivation-resistant and -sensitive neurons. These experiments show that DRG neurons expressing trk require NGF for survival. Furthermore, at least some of the DRG neurons that do not require NGF express the high affinity receptor for another neurotrophin. Finally, these experiments provide evidence that trk, and not p75NGFR, is the primary effector of NGF action in vivo.

The NGFI-B protein, an inducible member of the thyroid/steroid receptor family, is rapidly modified posttranslationally

The NGFI-B gene is rapidly activated by a variety of stimuli that induce cells to differentiate or proliferate. It encodes a protein with a predicted molecular mass of congruent to 61 kDa and is a member of the thyroid/steroid hormone receptor gene family. To characterize this protein, monoclonal antibodies were raised against a bacterial TrpE-NGFI-B fusion protein that encompasses a large portion (Glu-410 to Leu-527) of the carboxy-terminal domain of NGFI-B. These antibodies detected a protein that was rapidly synthesized in response to nerve growth factor (NGF) and migrated as a broad band on sodium dodecyl sulfate-polyacrylamide gels with an apparent molecular mass that ranged from 63 to 88 kDa. Pulse-chase analysis demonstrated that NGFI-B was rapidly posttranslationally modified and was a short-lived protein. NGFI-B was found to be a phosphorylated protein, and the multiple NGFI-B species coalesced into a single, more rapidly migrating species when treated with alkaline phosphatase. PC12 cells grown in the absence of NGF contained low levels of NGFI-B that was underphosphorylated. Epidermal growth factor, phorbol ester, and the calcium ionophore A23187 stimulated the synthesis of NGFI-B that was composed largely of underphosphorylated, rapidly migrating species. In contrast, basic fibroblast growth factor, which promotes differentiation of PC12 cells, induced the synthesis of NGFI-B species similar to those synthesized in response to NGF treatment. The underphosphorylated NGFI-B found in uninduced PC12 cells was found only in the nucleus, whereas NGFI-B in NGF-stimulated PC12 cells was present in approximately equal quantities in the cytoplasm and nucleus. Consistent with the cellular distribution observed in nonstimulated PC12 cells, the highly phosphorylated species were predominantly cytoplasmic whereas the more rapidly migrating forms were nuclear.

Liver fatty acid-binding protein: a marker for studying cellular differentiation in gut epithelial neoplasms

Human liver fatty acid binding protein is a 127 residue cytoplasmic protein synthesized in liver and in the intestinal epithelium. Previous studies of normal and transgenic mice indicated that the liver fatty acid-binding protein gene is a sensitive marker of enterocytic differentiation. This study shows the use of immunohistochemical methods to examine liver fatty acid-binding protein gene expression in normal human colonic epithelium, colonic villoglandular adenomas, nonmucinous and mucinous adenocarcinomas, and several types of noncolonic epithelial neoplasms. Cells containing liver fatty acid-binding protein were found in normal colonic epithelium, in two thirds of colorectal villoglandular adenomas and nonmucinous adenocarcinomas, and in one third of mucinous adenocarcinomas but not in noncolonic, nonhepatic carcinomas. All liver fatty acid-binding protein-positive colonic adenomas and adenocarcinomas contained patches of immunoreactive cells distributed among histologically identical patches of cells without liver fatty acid-binding protein immunoreactivity. This "mosaicism" was also found in metastases from liver fatty acid-binding protein-positive colonic adenocarcinomas. Immunostaining of these liver fatty acid-binding protein-positive tissues for carcinoembryonic antigen did not show a mosaic cellular pattern in its expression. These data suggest that within a given neoplasm, differences exist in the differentiation programs of monoclonally-derived, malignant colonic epithelial cells and that liver fatty acid-binding protein is a useful marker for operationally defining these subpopulations. Liver fatty acid-binding protein is also a potentially useful diagnostic marker for colorectal and hepatic carcinomas.

A 29-nucleotide DNA segment containing an evolutionarily conserved motif is required in cis for cell-type-restricted repression of the chicken alpha-smooth muscle actin gene core promoter

A series of 5' deletion mutations of the upstream flanking sequences of the chicken alpha-smooth muscle (aortic) actin gene was prepared and inserted into the chloramphenicol acetyltransferase expression vector pSV0CAT. Deletion recombinants were transfected into fibroblasts, which actively express the alpha-smooth muscle actin gene, and primary myoblast cultures, which accumulate much lower quantities of alpha-smooth muscle actin mRNAs. The first 122 nucleotides of 5'-flanking DNA were found to contain a "core" promoter capable of accurately directing high levels of transcription in both fibroblasts and myotubes. The activity of this core promoter is modulated in fibroblasts by a "governor" element(s) located at least in part between nucleotides -257 and -123. This region contains sequences potentially conserved between mammalian and avian alpha-smooth muscle actin genes as well as one of a pair of 16-base-pair inverted CCAAT box-associated repeats which are conserved among all chordate muscle actin genes examined to date. A smaller DNA segment (-151 to -123) containing these upstream CCAAT box-associated repeats was sufficient to suppress expression of the core promoter in muscle cultures, suggesting that the upstream CCAAT box-associated repeats play a negative role in the alpha-smooth muscle actin gene promoter.

The nontranscribed chicken calmodulin pseudogene cross-hybridizes with mRNA from the slow-muscle troponin C gene

A chicken calmodulin pseudogene with no introns was previously shown to hybridize under stringent conditions with an mRNA species present in skeletal and cardiac muscles, yet it would not hybridize to calmodulin mRNA (J. P. Stein, R. P. Munjaal, L. Lagace', E. C. Lai, B. W. O'Malley, and A. R. Means, Proc. Natl. Acad. Sci. USA 80:6485-6489, 1983). Using the pseudogene as a probe, we isolated a full-length cDNA corresponding to this mRNA from a chicken breast muscle library and showed by sequence analysis that it encodes slow-muscle troponin C and not the pseudogene product. Hybridization between the calmodulin pseudogene and slow-muscle troponin C cDNA is due to a short region of high homology in those nucleotides that encode helices B and C of troponin C and calmodulin. Genomic Southern analysis showed the calmodulin pseudogene and the gene for slow-muscle troponin C to exist as distinct single copies.

Structure and complete nucleotide sequence of the chicken alpha-smooth muscle (aortic) actin gene. An actin gene which produces multiple messenger RNAs

The alpha-smooth muscle (aortic) actin gene is a distinct member of the actin multigene family which is expressed in vascular smooth muscle cells. We have determined the complete nucleotide sequence of 11 kilobase pairs of genomic DNA encoding the chicken alpha-smooth muscle actin gene. This single copy gene specifies a protein identical in sequence to the major alpha-actin from bovine aorta. The protein-coding sequences are interrupted by seven introns which are at codons specifying amino acid residues 41/42, 84/85, 121/122, 150, 204, 267, and 327/328. An eighth intron was found in the mRNA 5' untranslated region. The 5' flanking sequences contain elements which are conserved in other chicken muscle actin genes. Additional sequences at the 5' end of the gene may be conserved in at least one human actin gene. We have identified at least four messenger RNAs ranging in size from approximately 1370 to 2700 nucleotides (excluding poly(A) tails) which are transcribed from the alpha-smooth muscle actin gene. These RNAs differ in the length of their 3' untranslated regions, probably as a result of the utilization of alternative polyadenylation signals. This is the first report of an actin gene with multiple mRNA transcripts.

Exchange assay for androgen receptors in the presence of molybdate

Several reports have shown that sodium molybdate stabilizes steroid hormone receptors. We have utilized these observations to develop an exchange assay for the androgen receptor at elevated temperatures. Exchange was found to be complete after 30 min at 30 degrees C. Receptor degradation was negligible during this treatment. Scatchard analysis indicated that the dissociation constant of the androgen receptor was similar both in the absence (Kd = 3.9 nM) and presence (Kd = 2.9 nM) of molybdate. Steroid specificity of the androgen receptor was unaltered by this treatment. The exchange procedure was reproducible, with an interassay variation of 2.45% and intraassay variation less than 10.0%. Using this assay, highest concentrations of androgen binding were measured in androgen target tissues of the rat (Dunning R3327 tumor, prostate and seminal vesicle; 23.37, 20.20 and 19.84 fmol/mg protein respectively). Lower concentrations were observed in other tissues (lung, brain, heart, spleen, liver and kidney; 9.06, 5.63, 3.50, 2.42, 2.33 and 1.36 fmol/mg protein respectively). These results demonstrate that molybdate stabilization of the androgen receptor allows efficient steroid exchange without significant alteration of the receptor's steroid binding properties. Furthermore, this exchange assay can be used to obtain a reasonable measurement of receptor concentrations in different androgen target tissues.

Inventors of new selves

This paper delineates a pattern of personality organization in which an individual is self-defined as having an identity that has been produced independently of all prior experiences. Usually there is a history of several radical changes of self-concept, in the conscious sense. Two psychodynamic bases of this pattern are discussed: one involving a flight from engulfment in others' perceptions and definitions, and the other involving a flight from a sense of irrevocable inner badness. In both cases, the childhood origins appear to be located in the pathogenic responses of caretakers during the phases of separation and individuation. Patients showing this pattern present special problems for the psychoanalyst. The main hazard one encounters in treating such people is that the patient will respond to the analyst's efforts to illuminate his or her personality structure and psychic origins with a sudden redefinition of the self and a breaking off of therapy. We have presented some treatment recommendations based on our experiences working with such people that involve substantial modifications of classical analytic technique. Central in these recommendations is the emphasis we have placed on the potential value of the analyst's empathically guided personal openness in the conduct of therapy.