Synergistic Suppression of NF1 Malignant Peripheral Nerve Sheath Tumor Cell Growth in Culture and Orthotopic Xenografts by Combinational Treatment with Statin and Prodrug Farnesyltransferase Inhibitor PAMAM G4 Dendrimers

Neurofibromatosis type 1 (NF1) is a disorder in which RAS is constitutively activated due to the loss of the Ras-GTPase-activating activity of neurofibromin. RAS must be prenylated (i.e., farnesylated or geranylgeranylated) to traffic and function properly. Previous studies showed that the anti-growth properties of farnesyl monophosphate prodrug farnesyltransferase inhibitors (FTIs) on human NF1 malignant peripheral nerve sheath tumor (MPNST) cells are potentiated by co-treatment with lovastatin. Unfortunately, such prodrug FTIs have poor aqueous solubility. In this study, we synthesized a series of prodrug FTI polyamidoamine generation 4 (PAMAM G4) dendrimers that compete with farnesyl pyrophosphate for farnesyltransferase (Ftase) and assessed their effects on human NF1 MPNST S462TY cells. The prodrug 3-tert-butylfarnesyl monophosphate FTI-dendrimer (i.e., IG 2) exhibited improved aqueous solubility. Concentrations of IG 2 and lovastatin (as low as 0.1 μM) having little to no effect when used singularly synergistically suppressed cell proliferation, colony formation, and induced N-RAS, RAP1A, and RAB5A deprenylation when used in combination. Combinational treatment had no additive or synergistic effects on the proliferation/viability of immortalized normal rat Schwann cells, primary rat hepatocytes, or normal human mammary epithelial MCF10A cells. Combinational, but not singular, in vivo treatment markedly suppressed the growth of S462TY xenografts established in the sciatic nerves of immune-deficient mice. Hence, prodrug farnesyl monophosphate FTIs can be rendered water-soluble by conjugation to PAMAM G4 dendrimers and exhibit potent anti-tumor activity when combined with clinically achievable statin concentrations.

Naturally occurring autoimmune disease in (NZB X NZW) F1 mice is correlated with suppression of MZ B cell development due to aberrant B Cell Receptor (BCR) signaling, which is exacerbated by exposure to inorganic mercury

Autoimmune diseases are multifactorial and include environmental as well as genetic drivers. Although much progress has been made in understanding the nature of genetic underpinnings of autoimmune disease, by comparison much less is understood regarding how environmental factors interact with genetics in the development of autoimmunity and autoimmune disease. In this report, we utilize the (NZB X NZW) F1 mouse model of Systemic Lupus Erythematosus (SLE). Mercury is a xenobiotic that is environmentally ubiquitous and is epidemiologically linked with the development of autoimmunity. Among other attributes of human SLE, (NZB X NZW) F1 mice spontaneously develop autoimmune-mediated kidney disease. It has been previously shown that if (NZB X NZW) F1 mice are exposed to inorganic mercury (Hg2+), the development of autoimmunity, including autoimmune kidney pathology, is accelerated. We now show that in these mice the development of kidney disease is correlated with a decreased percentage of marginal zone (MZ) B cells in the spleen. In Hg2+-intoxicated mice, kidney disease is significantly augmented, and matched by a greater decrease in MZ B cell splenic percentages than found in control mice. In Hg2+- intoxicated mice, the decrease in MZ B cells appears to be linked to aberrant B Cell Receptor (BCR) signal strength in transitory 2 (T2) B cells, developmental precursors of MZ B cells.

Demyelination-Remyelination in the Central Nervous System: Ligand-Dependent Participation of the Notch Signaling Pathway

Multiple sclerosis (MS) is an immune-mediated CNS disease mostly affecting young people. MS and other neurodegenerative and white matter disorders involve oligodendrocyte (OL) damage and demyelination. Therefore, elucidating the signaling pathways involved in the remyelination process through the maturation of OL progenitor cells (OPCs) may contribute to the development of new therapeutic approaches. In this context, this paper further characterizes toxic cuprizone (CPZ)-induced demyelination and spontaneous remyelination in rats and investigates the role of ligand-dependent Notch signaling activation along demyelination/remyelination both in vivo and in vitro. Toxic treatment generated an inflammatory response characterized by both microgliosis and astrogliosis. Interestingly, early demyelination revealed an increase in the proportion of Jagged1+/GFAP+ cells, which correlated with an increase in Jagged1 transcript and concomitant Jagged1-driven Notch signaling activation, particularly in NG2+ OPCs, in both the corpus callosum (CC) and subventricular zone (SVZ). The onset of remyelination then exhibited an increase in the proportion of F3/contactin+/NG2+ cells, which correlated with an increase in F3/contactin transcript during ongoing remyelination in the CC. Moreover, neurosphere cultures revealed that neural progenitor cells (NPCs) present in the brain SVZ of CPZ-treated rats recapitulate in vitro the mechanisms underlying the response to toxic injury observed in vivo, compensating for mature OL loss. Altogether, the present results offer strong evidence of cell-type and ligand-specific Notch signaling activation and its time- and area-dependent participation in toxic demyelination and spontaneous remyelination.

A computed tomography study of the fibula: morphology, morphometry, intramedullary anatomy, application prospects on intramedullary nailing

PURPOSE

The intramedullary percutaneous pinning in fractures of the lateral malleolus is a technique of osteosynthesis that can reduce complications of ORIF. Our study describes the morphology and the morphometry of the fibula, in particular intramedullary, so as to specify the best fibular nail features.

METHODS

We conducted a retrospective study on CT acquisitions of fibulae in vivo. We studied total length, and the distal malleolar angle. Regarding intramedullary morphology, six axial study levels were defined. Each level was assigned a morphometric classification (oval, triangular, quadrangular or irregular), and a measure of the diameter of the cavity. The distance between the smaller diameter and the malleolar tip was investigated.

RESULTS

We included 50 patients for 97 fibulae. The average age was 66.5 years. The irregular morphology type was the most frequently found. The average length was 370.5 mm (SD = 18.1; CI 95% [366.9; 374.1]), the average distal malleolar angle was 163.5° (SD = 3.7; CI 95% [162.7; 164.2]). The average minimal intramedullary diameter at malleolus level was 3.2 mm (SD = 1.2; CI 95% [3.0; 3.5]), with a minimum size reaching 95.8 mm (SD = 13.8; CI 95% [93.0; 98.5]) of the malleolar tip.

CONCLUSIONS

The analysis of morphological parameters of the fibula, in particular the lateral malleolus and intramedullary morphology is necessary for the design of a morpho-adapted nail. Interpersonal variability must be taken into account by the implant industry to offer nails of suited lengths and diameters.

TGF-β pro-oligodendrogenic effects on adult SVZ progenitor cultures and its interaction with the Notch signaling pathway

Adult neural progenitor cells (NPCs) are capable of differentiating into neurons, astrocytes, and oligodendrocytes throughout life. Notch and transforming growth factor β1 (TGF-β) signaling pathways play critical roles in controlling these cell fate decisions. TGF-β has been previously shown to exert pro-neurogenic effects on hippocampal and subventricular zone (SVZ) NPCs in vitro and to interact with Notch in different cellular types. Therefore, the aim of our work was to study the effect of TGF-β on adult rat brain SVZ NPC glial commitment and its interaction with Notch signaling. Initial cell characterization revealed a large proportion of Olig2+, Nestin+, and glial fibrillary acidic protein (GFAP+) cells, a low percentage of platelet-derived growth factor receptor α (PDGFRα+) or NG2+ cells, and <1% Tuj1+ cells. Immunocytochemical analyses showed a significant increase in the percentage of PDGFRα+, NG2+, and GFAP+ cells upon four-day TGF-β treatment, which demonstrates the pro-gliogenic effect of this growth factor on adult brain SVZ NPCs. Real-time polymerase chain reaction analyses showed that TGF-β induced the expression of Notch ligand Jagged1 and downstream gene Hes1. Notch signaling inhibition in cultures treated with TGF-β produced a decrease in the proportion of PDGFRα+ cells, while TGF-β receptor II (TβRII) inhibition also rendered a decrease in the proportion of PDGFRα+ cells, concomitantly with a decrease in Jagged1 levels. These findings demonstrate the participation of Notch signaling in TGF-β effects and illustrate the impact of TGF-β on glial cell fate decisions of adult brain SVZ NPCs, as well as on oligodendroglial progenitor cell proliferation and maturation.

Epidermal Growth Factor Receptor Kinase Inhibitors Synergize with TCDD to Induce CYP1A1/1A2 in Human Breast Epithelial MCF10A Cells

CYP1A1 and CYP1A2 are transcriptionally activated in the human normal breast epithelial cell line MCF10A following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Shifting MCF10A cultures to medium deficient in serum and epidermal growth factor (EGF) caused rapid reductions in the activated (i.e., phosphorylated) forms of extracellular regulated kinases (ERKs) and the epidermal growth factor receptor (EGFR). Shifting to serum/EGF-deficient medium also enhanced TCDD-mediated induction of cytochrome P450 (CYP)1A1 Treatment of cells cultured in complete medium with the EGFR inhibitors gefitinib (Iressa), AG1478, and CI-1033 resulted in concentration-dependent reductions of active EGFR and ERKs, and increased CYP1A1 mRNA content ∼3- to 18-fold above basal level. EGFR inhibitors synergized with TCDD and resulted in transient CYP1A1 and CYP1A2 mRNA accumulations ∼8-fold greater (maximum at 5 hours) than that achieved with only TCDD. AG1478, gefitinib, and TCDD individually induced small increases (∼1.2- to 2.5-fold) in CYP1A1 protein content but did not cause additive or synergistic accumulations of CYP1A1 protein when used in combination. The mitogen-activated protein kinase kinase inhibitor PD184352 inhibited ERK and EGFR activation in a concentration-dependent fashion without causing CYP1A1 mRNA accumulation. However, cotreatment with PD184352 potentiated TCDD-mediated CYP1A1 induction. TCDD-mediated induction of CYP1A1 in MCF7-TET on-EGFR cells, a MCF7 variant in which EGFR expression can be controlled, was not affected by the activity status of EGFR or ERKs. Hence, EGFR signaling mutes both basal and ligand-induced expression of two aryl hydrocarbon receptor-responsive P450s in MCF10A cultures. However, these effects are cell context-dependent. Furthermore, CYP1A1 mRNA and protein abundance are not closely coupled in MCF10A cultures.

Impact of muscle activation on ranges of motion during active elbow movement in children with spastic hemiplegic cerebral palsy

BACKGROUND

Children with spastic hemiplegic cerebral palsy are restricted in their daily activities due to limited active ranges of motion of their involved upper limb, specifically at the elbow. Their impaired muscles are frequently targeted by anti-spastic treatments that reduce muscle tone. But these treatments do not necessarily improve the limb function. There is a lack of comprehensive knowledge of the quantitative relations between muscle activation and joint active ranges of motion. Consequently, the objective of this study is to quantify the impact of muscle activation on the elbow active ranges of motion.

METHODS

During voluntary elbow pronation/supination and extension/flexion movements, kinematic and electromyographic measurements were collected from the involved upper limb of 15 children with spastic hemiplegic cerebral palsy (mean age=8.7 years, standard deviation=2.2) and the dominant upper limb of 15 age-matched children who are typically developing. Representative indicators of the muscle activation, such as the muscle co-activation, were extracted from the electromyographic measurements.

FINDINGS

Muscle co-activation in the involved upper limb accounted for 78% and 59% of the explained variance of the supination and extension limited active ranges of motion respectively. The agonist and antagonist muscle activations were both longer in the involved upper limb.

INTERPRETATIONS

This study succeeded in quantifying the impact of longer antagonist muscle activation on decreased elbow active ranges of motion in children with spastic hemiplegic cerebral palsy. Longer agonist muscle activation suggests that strengthening agonist muscles could increase the extension and supination ranges of motion, which constitutes a perspective of future clinical studies.

p-Anilinoaniline enhancement of dioxin-induced CYP1A1 transcription and aryl hydrocarbon receptor occupancy of CYP1A1 promoter: role of the cell cycle

The aryl hydrocarbon receptor (AhR) is targeted by ubiquitination for degradation by the proteasome shortly after its activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In silico screening identified p-anilinoaniline (pAA) as a putative inhibitor of an E2 ligase that partners with an E3 ligase implicated in AhR ubiquitination. We investigated whether pAA could modify AhR-dependent activation of its target gene CYP1A1. pAA (1-200 μM) alone did not affect AhR content, or stimulate CYP1A1 mRNA accumulation in human mammary epithelial MCF10A cultures. However, pretreatment with ≥100 μM pAA suppressed TCDD-induced CYP1A1 activation and AhR degradation via its functioning as an AhR antagonist. At a lower concentration (25 μM), pAA cotreatment increased TCDD-induced CYP1A1 mRNA accumulation, without inhibiting AhR turnover or altering CYP1A1 mRNA half-life. Whereas TCDD alone did not affect MCF10A proliferation, 25 μM pAA was cytostatic and induced a G(1) arrest that lasted ∼7 h and induced an S phase arrest that peaked 5 to 8 h later. TCDD neither affected MCF10A cell cycle progression nor did it alter pAA effects on the cell cycle. The magnitude of CYP1A1 activation depended upon the time elapsed between pAA pretreatment and TCDD addition. Maximal AhR occupancy of the CYP1A1 promoter and accumulation of CYP1A1 heterogeneous nuclear RNA and mRNA occurred when pAA-pretreated cultures were exposed to TCDD in late G(1) and early/mid S phase. TCDD-mediated induction of CYP2S1 was also cell cycle-dependent in MCF10A cultures. Similar studies with HepG2 cultures indicated that the cell cycle dependence of CYP1A1 induction is cell context-dependent.

Nonesterified cholesterol content of lysosomes modulates susceptibility to oxidant-induced permeabilization

Reactive oxygen species (ROS) can induce lysosomal membrane permeabilization (LMP). Photoirradiation of murine hepatoma 1c1c7 cultures preloaded with the photosensitizer NPe6 generates singlet oxygen within acidic organelles and causes LMP and the activation of procaspases. Treatment with the cationic amphiphilic drugs (CADs) U18666A, imipramine, and clozapine stimulated the accumulation of filipin-stainable nonesterified cholesterol/sterols in late endosomes/lysosomes, but not in mitochondria. Concentration-response studies demonstrated an inverse relationship between lysosomal nonesterified cholesterol/sterol contents and susceptibility to NPe6 photoirradiation-induced intracellular membrane oxidation, LMP, and activation of procaspase-9 and -3. Similarly, the kinetics of restoration of NPe6 photoirradiation-induced LMP paralleled the losses of lysosomal cholesterol that occurred upon replating U18666A-treated cultures in CAD-free medium. Consistent with the oxidation of lysosomal cholesterol, filipin staining in U18666A-treated cultures progressively decreased with increasing photoirradiating light dose. U18666A also suppressed the induction of LMP and procaspase activation by exogenously added hydrogen peroxide. However, neither U18666A nor imipramine suppressed the induction of apoptosis by agents that did not directly induce LMP. These studies indicate that lysosomal nonesterified cholesterol/sterol content modulates susceptibility to ROS-induced LMP and possibly does so by being an alternative target for oxidants and lowering the probability of damage to other lysosomal membrane lipids and/or proteins.

The chemotherapeutic agents XK469 (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid) and SH80 (2-{4-[(7-bromo-2-quinolinyl)oxy]phenoxy}propionic acid) inhibit cytokinesis and promote polyploidy and induce senescence

The therapeutic usefulness of the quinoxaline derivatives XK469 (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid) and SH80 (2-{4-[(7-bromo-2-quinolinyl)oxy]phenoxy}propionic acid) has been attributed to their abilities to induce G(2)/M arrest and apoptotic or autophagic cell death. Concentrations of XK469 or SH80 > or = 5 microM were cytostatic to cultures of the normal murine melanocyte cell line Melan-a. Higher concentrations caused dose-dependent cytotoxicity. Concentrations > or =10 microM provoked dramatic morphological changes typified by marked increases in cell size and granularity. XK469/SH80-treated cultures accumulated tetraploid (4N) DNA-containing cells within 24 h of treatment, an 8N population within 3 days, and a 16N population within 5 days. Increases in ploidy correlated with the appearance of multinucleated cells. Under no circumstances did cells exhibit evidence of furrow formation. Both drugs suppressed cytokinesis in additional mammalian cell lines. Cytotoxic concentrations of XK469 elevated DEVDase activities (a measure of procaspase-3/7 activation) and enhanced cellular staining by a fluorescent analog of the pan caspase inhibitor valine-alanine-aspartic acid-fluoromethyl ketone within 48 to 96 h of treatment. Within 48 h of treatment, cytostatic and cytotoxic concentrations of XK469 elevated p21 contents, reduced Bcl-2 and Bcl-XL contents, and induced autophagy, as monitored by the accumulation of phosphatidylethanolamine-modified cleavage product of microtubule-associated protein light chain 3 (LC3-II). Cultures treated with > or =10 microM XK469 or SH80 for 5 days could not be induced to divide upon removal of drugs. Such cultures maintained high LC3-II contents, exhibited reduced cyclin E and D1 contents, and extensively expressed senescence-associated beta-galactosidase within 14 to 17 days of cessation of drug treatment. Hence, XK469 and SH80 inhibit cytokinesis, promote polyploidy, and induce senescence in Melan-a cells.

Properties of cryptic epitopes and their corresponding antibodies as indicated by the study of human and ovine growth hormones

Antibodies (Ab) directed to hidden antigenic determinants (cryptotopes) are undesirable because they are not neutralizing. Additionally, we have previously demonstrated a close association between the extent of Ab to cryptic determinants and the expression of autoantibodies (autoAb) under some experimental conditions. Thus, the first objective of this work was to establish the physicochemical characteristics of Ab to cryptotopes and the second one was to examine the structural features of cryptic epitopes themselves. Using human and ovine growth hormones (hGH and oGH) as antigenic models and competition ELISA under different conditions of temperature, pH or ionic strength, we did not find any difference between the binding properties of anti-cryptic epitope antibodies (Ab) and anti-native epitope Ab. Then, using synthetic peptides and tryptic digests and direct and competition ELISAs we studied the structures of cryptic hGH and oGH epitopes. Isolated peptides either in solution or adsorbed on microplates failed to react. Partially digested hGH was recognized only when insolubilized on microplates, and anti-oGH Ab only reacted with a large fragment of the hormone either in solution or insolubilized. These results indicate that, at least in the case of hGH and oGH, cryptic epitopes are not simple linear sequences, as commonly referred without any evidence, but new exposed conformational structures different from those found in the native antigen.

Automatic decomposition of multichannel intramuscular EMG signals

We describe an automatic algorithm for decomposing multichannel EMG signals into their component motor unit action potential (MUAP) trains, including signals from widely separated recording sites in which MUAPs exhibit appreciable interchannel offset and jitter. The algorithm has two phases. In the clustering phase, the distinct, recurring MUAPs in each channel are identified, the ones that correspond to the same motor units are determined by their temporal relationships, and multichannel templates are computed. In the identification stage, the MUAP discharges in the signal are identified using matched filtering and superimposition resolution techniques. The algorithm looks for the MUAPs with the largest single channel components first, using matches in one channel to guide the search in other channels, and using information from the other channels to confirm or refute each identification. For validation, the algorithm was used to decompose 10 real 6-to-8-channel EMG signals containing activity from up to 25 motor units. Comparison with expert manual decomposition showed that the algorithm identified more than 75% of the total 176 MUAP trains with an accuracy greater than 95%. The algorithm is fast, robust, and shows promise to be accurate enough to be a useful tool for decomposing multichannel signals. It is freely available at http://emglab.stanford.edu.

Simulation of progressive spinal deformities in Duchenne muscular dystrophy using a biomechanical model integrating muscles and vertebral growth modulation

BACKGROUND

Ninety percent of Duchenne muscular dystrophy patients develop scoliosis in parallel with evident muscular and structural impairment. Altered muscular spinal loads acting on growing vertebrae are likely to promote a self-sustaining spinal deformation process. The purpose of this study was to simulate the effect of asymmetrical fat infiltration of the erector spinae muscles combined with vertebral growth modulation over a period of growth spurt.

METHODS

A finite element model of the trunk was built. It integrates (1) longitudinal growth of vertebral bodies and its modulation due to mechanical stresses, (2) muscles and control processes generating muscle recruitment and forces. Three different impairments of the erector spinae muscles were considered and their actions over 12 consecutive cycles representing a span of 12 months were analyzed.

FINDINGS

When asymmetrical muscle degeneration was simulated and weaker erector spinae muscles were located on the convex side of the curve, mild scoliosis (Cobb angle of 8-19 degrees ) was induced in the frontal plane and the kyphosis increased from 72 degrees to 110 degrees in all simulations. Those changes were accompanied by a substantial increase of muscle activity in the Rectus Abdominus and Obliquus Internus.

INTERPRETATION

Scoliosis as documented in the literature were induced through an asymmetrical activity in the erector spinae muscles and it can be hypothesized that the Rectus Abdominus and Obliquus Internus have a role in maintaining balance and counteracting against spine torsion. This study demonstrated the feasibility of the modeling approach to investigate a musculo-skeletal deformation process based on a neuromuscular deficit.

The peptide specificities of the autoantibodies elicited by mouse hepatitis virus A59

Synthetic decapeptides (N = 206) covering the entire sequence of mouse liver fumarylacetoacetate hydrolase (FAH) were used to analyze the specificities of the autoantibodies (autoAb) elicited towards this enzyme in mice infected with mouse hepatitis virus (MHV). These autoAb bound mainly to N- and C-terminal FAH peptides, the most reactive sequences being 1–50 and 390–420, respectively. Surprisingly, although FAH sequence 1–50 shares a high degree of homology with various MHV proteins, the C-terminal portion does not. Moreover, whereas the autoAb reacted with homologous peptides surrounding residues 70, 160 and 360, non-similar sequences around residues 130, 210, 240, 250, and 300 were also recognized, indicating that autoAb were not restricted to epitopes with sequence homologies. There was also a lack of correlation between the amount of anti-MHV or anti-FAH antibodies produced and the reactivity towards the peptides. Moreover, the spectrum of peptides recognized by the autoAb of a given mouse did not change significantly with time, which suggests that the MHV-elicited autoimmune response does not induce an epitope recognition spreading. Finally, anti-FAH Ab produced after immunization with rat liver FAH recognized essentially the same mouse FAH regions than autoAb from MHV-infected mice. Results indicated that the induction of the autoAb is not only related to molecular or structural mimicry, but rather supports the Danger model, in which any aggression, in this case the MHV infection, is susceptible to trigger the production of autoAb.

Aryl hydrocarbon receptor modulation of tumor necrosis factor-alpha-induced apoptosis and lysosomal disruption in a hepatoma model that is caspase-8-independent

Recent studies suggest that the aryl hydrocarbon receptor (AhR) modulates susceptibilities to some pro-apoptotic agents. AhR-containing murine hepatoma 1c1c7 cultures underwent apoptosis following exposure to tumor necrosis factor-alpha (TNFalpha) + cycloheximide (CHX). In contrast, Tao cells, an AhR-deficient variant of the 1c1c7 line, were refractory to this treatment. AhR sense/antisense transfection studies demonstrated that AhR contents influenced susceptibility to the pro-apoptotic effects of TNFalpha + CHX. 1c1c7 cells and all variants expressed comparable amounts of TNF receptor-1 and TRADD. However, no cell line expressed FADD, and consequently pro-caspase-8 was not activated. AhR content did not influence JNK and NF-kappaB activation. However, Bid and pro-caspase-9, -3, and -12 processing occurred only in AhR-containing cells. Analyses of cathepsin B and D activities in digitonin-permeabilized cultures and the monitoring of cathepsin B/D co-localization with Lamp-1 indicated that TNFalpha + CHX disrupted late endosomes/lysosomes in only AhR-containing cells. Stabilization of acidic organelles with 3-O-methylsphingomyelin inhibited TNFalpha + CHX-induced apoptosis. The cathepsin D inhibitor pepstatin A suppressed in vitro cleavage of Bid by 1c1c7 lysosomal extracts. It also delayed the induction of apoptosis and partially prevented Bid cleavage and the activation of pro-caspases-3/7 in cultures treated with TNFalpha + CHX. Similar suppressive effects occurred in cultures transfected with murine Bid antisense oligonucleotides. These studies showed that in cells where pro-caspase-8 is not activated, TNFalpha + CHX can initiate apoptosis through lysosomal disruption. Released proteases such as cathepsin D trigger the apoptotic program by activating Bid. Furthermore, in the absence of exogenous ligand, the AhR modulates lysosomal disruption/permeability.

The staircase phenomenon at the corrugator supercilii muscle in comparison with the hand muscles

BACKGROUND

Phonomyography (PMG) is a novel method to monitor neuromuscular block. It is non-invasive and can be applied to any muscle. It can be used interchangeably with mechanomyography (MMG). The staircase phenomenon has not been investigated for this method or at the corrugator supercilii muscle. The purpose of this work was to determine the staircase effect at three different muscles using two different methods.

METHODS

In 10 patients undergoing general anaesthesia with sevoflurane, using a laryngeal mask airway without the aid of neuromuscular block, one piezo-electric microphone each was applied to the corrugator supercilii muscle and the first dorsal interosseus muscle. In addition, a force transducer was attached to the tip of the thumb to determine the force of the adductor pollicis muscle. Supramaximal stimulation at 1 Hz was used at the ulnar and the facial nerve. All signals were simultaneously recorded for 30 min. Data are presented as means (SD).

RESULTS

The staircase effect was significantly positive for the first dorsal interosseus muscle and the adductor pollicis muscle. The signal potentiation was not significantly different between the first dorsal interosseus muscle with a maximum increase at 148 (19)% using PMG, and the adductor pollicis muscle at 154 (22)% using MMG. The evoked signals reached a plateau after 15-18 min at both muscles. There was only a small initial increase in signal height at the corrugator supercilii to a maximum of 117 (20)% at 7 min, after which the signals decreased to reach a plateau at 25 min. In comparison with the signal height of 105 (25)% at 30 min, there was no significant difference of signal heights throughout the observation period.

CONCLUSIONS

A positive staircase phenomenon is found equally at the first dorsal interosseus muscle and the adductor pollicis muscle. There is no significant staircase effect at the corrugator supercilii muscle.

Sequence similarity and structural homologies are involved in the autoimmune response elicited by mouse hepatitis virus A59

The features of autoantibodies (autoAb) to liver fumarylacetoacetate hydrolase (FAH) elicited in mice infected with mouse hepatitis virus (MHV) were studied by ELISA and western-blot competition assays. All sera tested contained Ab to cryptic FAH epitopes according with results from western-blot tests, whereas ELISA data indicated that some of these same sera did recognize native epitopes of the autoantigen (autoAg). Such differences were detected in individual sera from various mouse strains, and were ascribed to the fact that proteins insolubilized on solid supports expose a variety of conformational and cryptic antigenic determinants.

On the other hand, whereas results from both experimental protocols showed that anti-MHV Ab did not cross-react with the soluble autoAg, the opposite situation did not show analogous results. Thus, binding of autoAb to insolubilized FAH could be inhibited by MHV depending on the mouse serum or the experimental protocol used.

Additionally, a set of synthetic homologous peptides from mouse FAH and various viral proteins was employed to analyze the Ab repertoire of MHV-infected mice. Results indicated that two homologous peptides were recognized by most Ab: the N-terminal sequences (1–10) from FAH and the nucleocapside, both sharing 50% of identity, and sequence 2317–2326 of the RNA polymerase, a peptide showing 30% of identity with FAH 11–20.

Results indicated that MHV-infection triggers at least three distinct Ab populations: anti-MHV, anti-FAH and cross-reacting Ab. This cross-reaction implies either sequential or conformational epitopes from both the viral proteins and the autoAg and may differ between individuals.

Differential susceptibilities of murine hepatoma 1c1c7 and Tao cells to the lysosomal photosensitizer NPe6: influence of aryl hydrocarbon receptor on lysosomal fragility and protease contents

Irradiation of murine hepatoma 1c1c7 cultures presensitized with N-aspartyl chlorin e6 (NPe6) caused lysosomal disruption and apoptosis. Tao cells, a variant of the 1c1c7 line having lower aryl hydrocarbon receptor (AhR) contents, were resistant to the pro-apoptotic effects of NPe6 in the same photodynamic therapy protocol. Colony-forming assays were used to establish light dose-dependent and NPe6 concentration-dependent cytotoxicity curves. Lysosomal breakage and cell survival paralleled one another in both cell types. When analyzed at comparable lethal dose conditions, the onset of apoptosis was delayed, and the magnitude of the apoptotic response was muted in Tao cells, as assessed by morphology, annexin V binding, caspase-3 activities, and analyses of Bid, procaspase-9, and pro-caspase-3 cleavage. In contrast, the kinetics/magnitude of pro-caspase-3 activation in the two cell lines were identical after exposure to HA14 -1 or Jo2 antibody, inducers of the intrinsic and extrinsic apoptotic pathways, respectively. Tao endosomal/lysosomal extracts contained approximately 50%, 35%, and 55% of the Bid cleavage and cathepsin B and D activities of 1c1c7 endosomes/lysosomes, respectively. Western blot analyses confirmed reduced cathepsin B/D contents in Tao cells. Analyses of 1c1c7/Tao variants engineered to express antisense/sense AhR constructs suggested that endosomal/lysosomal cathepsin B and D content, but not whole cell content, correlated with AhR expression. These studies provide a mechanism for the resistance of Tao cultures to the proapoptotic effects of a protocol causing targeted disruption of lysosomes. They also suggest that the AhR, in the absence of exogenous ligand, may affect the trafficking/processing of proteases normally found in endosomes/lysosomes.

THE JUN N-TERMINAL KINASE INHIBITOR SP600125 IS A LIGAND AND ANTAGONIST OF THE ARYL HYDROCARBON RECEPTOR

Exposure of the immortalized human breast epithelial cell line MCF10A to the Jun N-terminal kinase (JNK) inhibitor anthra[1,9-cd]pyrazol-6(2H)-one (SP600125) suppressed, in a concentration-dependent manner (IC50 is approximately 2 microM), the induction of CYP1A1 by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Cotreatment with SP600125 also suppressed the accumulation of TCDD-induced nuclear aryl hydrocarbon receptor (AhR)-DNA complexes, as assessed by electrophoretic mobility shift assays. Concentrations of SP600125 < or = 50 microM did not transform the AhR into a DNA-binding species when added to rat liver cytosol. However, addition of SP600125 to cytosol just before TCDD addition completely suppressed AhR transformation and DNA binding (IC50 approximately 7 microM). Sucrose gradient analyses using rat liver and murine hepatoma 1c1c7 extracts demonstrated that SP600125 competed with TCDD for binding to the AhR. These results suggest that SP600125 is an AhR ligand and functions as an AhR antagonist at concentrations used to pharmacologically inhibit JNK.

Effects of various adjuvants and a viral infection on the antibody specificity toward native or cryptic epitopes of a protein antigen

An immunization protocol that induces antibodies (Abs) directed to cryptic epitopes of a protein antigen (Ag) reduces the efficacy of vaccines that ideally should induce Abs against native epitopes. We have shown earlier that viral infections concomitant with immunization against a protein tend to shift the Ab specificity toward cryptic epitopes and tend to induce the production of autoantibodies (autoAbs). Here, we show the effects of three adjuvants on the Ab specificity in the absence or presence of a viral infection (lactate dehydrogenase-elevating virus or LDV), with human growth hormone (hGH) being, as before, the protein Ag. Pathogen-free CBA/Ht and BALB/c mice were immunized with hGH in the presence of complete Freund's adjuvant (CFA), monophosphoryl lipid A (MPL) or alum, with the animals being either infected with LDV or not infected with LDV. Conventional and competition enzyme-linked immunosorbent assays (ELISAs) indicated that in noninfected mice, CFA induced higher titres of anti-hGH Ab than did MPL or alum, with the Ab being almost totally directed to cryptic hGH epitopes. Strikingly, CFA plus LDV infection in CBA/Ht mice shifted the specificity of the anti-hGH Ab toward native epitopes, whereas the virus decreased the Ab titre when MPL or alum was used. Our Western blot results showed that 70% of mice immunized with hGH in the presence of any adjuvant produced autoAbs against a variety of tissue Ags. The amount of autoAb and the concentration of Ab to hGH cryptic epitopes did correlate, suggesting a relationship between both kinds of Ab. Significant differences were observed in the various effects of adjuvants and the viral infection between the two mouse strains used in this work.

Detection of mouse hepatitis virus infection by assay of anti-liver autoantibodies

The observation that mice infected with mouse hepatitis virus (MHV) develop autoantibodies directed mainly to liver fumarylacetoacetate hydrolase (FAH) enabled the development of an ELISA applicable to the detection of MHV-infection. The method, based on the titration of antibodies to semipurified FAH from rat liver, is easy, economical, and does not require the isolation of viral proteins from large MHV stocks. Furthermore, since sera from mice immunized with a purified fraction of the rat liver enzyme do react with its homologous protein, this antiserum can be used as a positive control avoiding the manipulation of samples from MHV-infected animals.

Electromyogram and kinematic analysis of lateral bending in idiopathic scoliosis patients

In adolescent idiopathic scoliosis (AIS), surgical planning currently relies on spinal flexibility evaluation using lateral bending radiographs. The aim was to evaluate the feasibility of non-invasive dynamic analysis of trunk kinematics and muscle activity in patients with AIS before surgical correction. During various lateral trunk bending tasks, erector spinae (18 sites) and abdominal (four sites) muscle activity was sampled using surface electrodes in ten AIS patients and in ten controls. Simultaneously, the spatial displacements of infrared emitting diodes located on the trunk were sampled. Parameters considered were the heterolateral-to-homolateral root-mean-square EMG ratios R at each site and total lateral bending and thoracic and lumbar curvature angle courses. Main alterations concerned apical muscle activity during left bending tasks. ANOVA results showed a significant effect of side (p = 2.1 x 10(-9)), EMG recording site (p = 1.9 x 10(-16)), pathology (p = 3.9 x 10(-16)) and task (p = 2.2 x 10(-11)) on R ratios. The R ratio at T10 and L1 for a simple lateral bending task during left bending averaged 4.8 (SD 4.3) and 3.0 (SD 3.1) in AIS patients, and 2.3 (SD 2.8) and 1.3 (SD 0.4) in controls (p = 6.4 x 10(-4) and 2.5 x 10(-3), LSD post hoc). This preliminary study allowed the development of a functional, non-invasive, non-irradiating dynamic tool for pre-operative evaluation in AIS.

Phorbol ester activation of a proteolytic cascade capable of activating latent transforming growth factor-betaL a process initiated by the exocytosis of cathepsin B

12-O-Tetradecanoylphorbol-13-acetate (TPA) suppresses the proliferation of the human breast epithelial cell line MCF10A-Neo by initiating proteolytic processes that activate latent transforming growth factor (TGF)-beta in the serum used to supplement culture medium. Within 1 h of treatment, cultures accumulated an extracellular activity capable of cleaving a substrate for urokinase-type plasminogen activator (uPA) and tissue plasminogen activator (tPA). This activity was inhibited by plasminogen activator inhibitor-1 or antibodies to uPA but not tPA. Pro-uPA activation was preceded by dramatic changes in lysosome trafficking and the extracellular appearance of cathepsin B and beta-hexosaminidase but not cathepsins D or L. Co-treatment of cultures with the cathepsin B inhibitors CA-074 or Z-FA-FMK suppressed the cytostatic effects of TPA and activation of pro-uPA. In the absence of TPA, exogenously added cathepsin B activated pro-uPA and suppressed MCF10A-Neo proliferation. The cytostatic effects of both TPA and cathepsin B were suppressed in cells cultured in medium depleted of plasminogen/plasmin or supplemented with neutralizing TGF-beta antibody. Pretreatment with cycloheximide did not suppress the exocytosis of cathepsin B or the activation of pro-uPA. Hence, TPA activates signaling processes that trigger the exocytosis of a subpopulation of lysosomes/endosomes containing cathepsin B. Subsequently, extracellular cathepsin B initiates a proteolytic cascade involving uPA, plasminogen, and plasmin that activates serum-derived latent TGF-beta.

Spinal mobility and EMG activity in idiopathic scoliosis through dynamic lateral bending tests

Lateral bending test is a common evaluation of AIS patients prior to their surgical correction. Traditionally this evaluation is made by the assessment of the curve's flexibility from side-bending radiographs. As a complement to this static test, dynamic bending was experimented while simultaneously quantifying muscular and kinematic behavior of the spine. The biggest contribution to total EMG output was 36% from lumbar muscles in healthy and 35% from abdominal muscles in scoliotic subjects. Continuous measuring of kinematics and muscle activation patterns throughout lateral bending could be an evaluation tool for distinguishing pathological from normal behavior.

Reduction of gait data variability using curve registration

Timing in peak gait values shifts slightly between gait trials. When averaged, the standard deviation (S.D.) in gait data may increase due to this inter-trial variability unless normalization is carried out beforehand. The objective of this study was to determine how curve registration, an alignment technique, can reduce inter-subject variability in gait data without perturbing the curve characteristics. Twenty young, healthy men participated in this study each providing a single gait trial. Gait was assessed by means of a four-camera high-speed video system synchronized to a force plate. A rigid body three-segment model was used in an inverse dynamic approach to calculate three-dimensional muscle powers at the hip, knee and ankle. Curve registration was applied to each of the 20 gait trials to align the peak powers. The mean registered peak powers increased by an average of 0.10 +/- 0.13 W/kg with the highest increases in the sagittal plane at push-off. After performing curve registration, the RMS values decreased by 13.6% and the greatest reduction occurred at the hip and knee, both in the sagittal plane. No important discontinuities were reported in the first and second derivatives of the unregistered and registered curves. Curve registration did not have much effect on the harmonic content. This would be an appropriate technique for application prior to any statistical analysis using able-bodied gait patterns.

EMG and kinematics of normal subjects performing trunk flexion/extensions freely in space

Ten normal subjects performed continuous trunk flexion/extensions (F/E) without any restraining apparatus at free, 3, 2.25 and 1.5 s periods and a fatiguing task of F/E at 1.5 s period during 45 s. Kinematics of the trunk was obtained with bilateral electromyographic (EMG) activity of the erector spinae (three levels), the abdominal oblique muscles and the rectus abdominis muscles. The free period chosen by the subjects was found to vary between 3.05 and 1.47 s. Lateral flexion of the spine was similar in each task but rotation about its longitudinal axis increased as the F/E period shortened. When left and right side EMG signals were grouped by level of recording, a significant difference in activity was found. Subjects who produced the slowest free F/E displayed larger fatigue indexes derived from the EMG signals for some of their back muscles than for other subjects. The flexion/relaxation phenomenon was considered present in a muscle if a level <10% of the maximum signal recorded during extension was detected. The phenomenon was found in >50% of the observations and occurred at a similar angle in each task. Kinematics and several characteristics of the EMG signals of the trunk were statistically independent of the speed of motion.

Mapping of the human upper arm muscle activity with an electrode matrix

Surface electrode matrices allow measurement of muscle activity while avoiding certain hazardous risks and inconvenience associated with invasive techniques. Major challenges of such equipment involve optimizing spatial resolution, and designing simple acquisition systems able to record simultaneously many potentials over large anatomical areas. We present a surface electromyography acquisition system comprising of 3 x 8 Ag-AgCl electrodes mounted onto an elastic band, which can be adjusted to fit an entire human upper limb segment. Using this equipment, we acquired a simultaneous representation of muscular activity from a segment of the upper limb surface of 6 healthy subjects during isometric contractions at various intensities. We found that the location of regions of highest activity depended on elbow torque direction but also varied among subjects. Signals obtained with such equipment can be used to solve the inverse problem and help optimize the electrode configuration in volume conduction studies. The efficacy of decision algorithms of multi-functional myoelectric prostheses can be tested with the global muscle activity patterns gathered. The electrode cuff could also be used in the investigation of fatigue and injury mechanisms during occupational activities.

Autoantibodies to cryptic epitopes elicited by infection with lactate dehydrogenase-elevating virus

Lactate dehydrogenase-elevating virus (LDV) produces a permanent infection in mice with a B-lymphocyte polyclonal activation leading to hypergammaglobulinaemia. Since LDV specifically suppressed antibodies to native epitopes in CBA/Ht, but not BALB/c, mice immunized against a protein antigen, we explored the relationship between such a change in antibody specificity and the expression of autoantibodies under the influence of LDV. Again in CBA/Ht, but not BALB/c, mice we observed another effect of LDV: the sera from infected CBA/Ht mice were found by enzyme-linked immunosorbant assay to contain antibodies to various mouse tissue extracts. Immunoblots revealed a large spectrum of autoantigens that differed markedly between animals. Western-blot competition experiments showed that the protein autoantigens had to be denatured to react with most of the autoantibodies. Despite the presence of these autoantibodies directed to cryptic epitopes, no specific tissue lesions could be ascribed to the autoimmune response elicited by LDV infection, since both mouse strains showed mild inflammatory reactions in liver and kidney.

[Back muscle activity during flexions/extensions in a second group of normal subjects]

Natural trunk movements and back muscle electromyographic (EMG) activity are seldom studied but are pertinent to daily life activities, which can lead to low-back pain. In this study, ten normal subjects performed trunk flexion/extensions (F/E) without any restraining apparatus. Duration of the F/E was either free, or at 3, 2.25 and 1.5 s. A fatiguing task consisted of continuous F/E movements accomplished at 1.5 s intervals during 90 s. Photodiodes were placed on the skin to obtain kinematics of the trunk. EMG signals of the back were recorded with 10 pairs of surface electrodes located at 3 levels of the erector spinae. It was found that the F/E movement duration chosen by the subjects varied between 4.07 and 2.07 s and the flexion amplitude varied between 55 degrees and 118 degrees. Similar variations in the amplitude of flexions were found for the tasks realized at fixed periods. The level of fatigue induced in the fatigue task was evaluated by comparing the energy of its EMG signals with those of the 1.5 s task. With this index, fatigue was detected in a few subjects only. Due to the length of the fatigue task (90 s long), it would seem that most of the subjects became adapted to the movements and could produced them more effectively (i.e. with less EMG) than during the 1.5 s task which was repeated only for few seconds.

Differential growth factor responses of epithelial cell cultures derived from normal human prostate, benign prostatic hyperplasia, and primary prostate carcinoma

Because of a lack of information of the optimum nutritional requirements, epithelial cells derived from normal human prostate and prostate tumors have been difficult to propagate in vitro, which hinders research in prostate carcinogenesis. In an effort to establish optimum nutritional conditions and differences in growth characteristics of normal human prostate (NP), benign prostatic hyperplasia (BPH), and prostatic carcinoma (PCA), we have compared the effects of several growth factors on cell proliferation and elucidated growth properties of low passage epithelial cells derived from NP, BPH, and PCA of an African-American patient. Primary and low passage cultures were propagated in serum-free keratinocyte basal medium (KBM) supplemented with insulin (5 micrograms/ml), hydrocortisone (0.5 microgram/ml), epidermal growth factor (EGF, 10 ng/ml), bovine pituitary extract (BPE; 50 micrograms/ml), cholera toxin (10 ng/ml), and antibiotics. Almost all NP, BPH, and PCA cells were positive for cytokeratins and prostate-specific antigen (PSA). The NP, BPH, and PCA cells were essentially diploid and lacked mutations in c-K-ras and c-Ha-ras oncogenes, and p53 tumor suppressor gene. However, they exhibited progressively accelerating growth parameters. The population doubling times of NP, BPH and PCA were 51 hr, 37 hr, and 29 hr, respectively; their saturation densities were 2.9 x 10(4)/cm2, 3.3 x 10(4)/cm2, and 7.2 x 10(4)/cm2, respectively. The NP and BPH cells required all of the growth factors in the medium, as deletion of any one of the above factors strongly inhibited their growth. The PCA cells, however, were independent of EGF and hydrocortisone. PC-3, an established human prostate cancer cell line, was independent of the growth factors tested. Fetal bovine serum (FBS) inhibited the growth of NP, BPH and PCA cells. In contrast, FBS stimulated the growth of the PC-3 cells in a concentration-dependent manner. These results indicate that in the absence of any apparent karyotype alterations and mutations in c-K-ras, c-Ha-ras and p53 genes, epithelial cells derived from NP, BPH, and PCA exhibit significant differences in their growth properties and responses to growth factors. These variations may represent early changes involved in prostate cancer, while gene mutations and cytogenetic alterations occur in advanced and/or metastatic tumors.

Changes in the hemiparetic limb with training. I. Torque output

The study concerns eleven patients who had suffered from a cerebro-vascular accident (CVA) less than 6 months previously and who were hospitalized for treatment. In addition to their multidisciplinary rehabilitation treatments, the patients consented to participate in an electromyographic (EMG) biofeedback program designed to increase their shoulder activity. From blocks of five individual isometric contractions, curves of both the mean torque and of its standard deviation (SD) were generated and from each of these, a mean value was obtained. These two measures were used to analyze the effects on the biofeedback training had induced on shoulder activity. The training induced negligible changes on the contralateral (CL) side. The mean torque value for the group was 31.02 post vs 30.99 Nm pre-training. However, for the hemiplegic (HEMI) limbs, some patients showed improvement while others did not. The treatment was considered a success when the mean torque values obtained in the last 2/3 of the training or at the post-training session were > or = 1.5 the values obtained during the pre-training session. Based on this criteria, it was found that six out of eleven patients did improve their muscular activity through the training. Among these, the improvement of four was greater during the 2/3 session than that observed at the post-training session. The six successful patients were found to have a pre-training upper extremity Fugl-Meyer score < or = 13. Two patients had a similar pre-training score of 11, and met the criteria of success, but the younger patient performed better than the older one. Patients with scores of 20 and higher did not meet the 1.5 criteria. A correlation (r = 0.80) was found between post/pre ratios of Fugl-Meyer scores and those of the mean torque: the test thus seems to have a limited usefulness for assessing local changes such as the effects of the biofeedback treatment on the shoulder.

Changes in the hemiparetic limb with training. II. EMG signal

Following a cerebro-vascular accident, motor deficits are usually associated with a selective atrophy of fast fatiguable muscle fibers. The reduction of output torque in spastic patients is considered to be caused by unfused twitches resulting from the reduction in the motor unit firing rate. To regain control of a paretic limb, these patients have to learn, through training, how to recruit an adequate number of intact motor units to generate the required functional movement. In hemiplegia, intra-subject variability makes difficult the assessment of the effects of any therapy treatments. Our objective here was thus to address the problem of the data variability and to analyze the electromyographic signal obtained from hemiplegic patients under biofeedback training. The experimental situation chosen was a very isolated but controlled motor activity (an isometric shoulder forward flexion). The results show that after training, 5 out of 11 patients could produce EMG signal from their affected deltoid whose mean value was 50% greater than before the training, while no appreciable change was observed for their unaffected deltoid. While these EMG changes on the HEMI side are correlated with greater torque output, the coefficient of correlation is slightly smaller after than before the training (r = 0.87 vs 0.89). It can be hypothesized that while the training was directed toward the deltoid, the patients in some ways developed new strategies for contracting their shoulder.

Endurance time characteristics of human ankle dorsiflexors and plantarflexors

The endurance time provides a convenient means to assess muscle fatigue resistance. The purpose of the experiments was to study endurance time characteristics of human ankle dorsiflexion and plantarflexion as a function of level of contraction. Nine subjects (four men, five women) were examined. The experimental protocol consisted of determining each individual maximum voluntary contraction (MVC) before each fatiguing experiment and undertaking only one fatiguing isometric contraction (dorsiflexion or plantarflexion) per day. Each subject produced at least six plantarflexion and six dorsiflexion contractions chosen from 15% to 90% MVC. An exponential model was fit to data for each individual and was then fit to the pooled data. The variance accounted for was over 99% for both dorsiflexion and plantarflexion mean values. As expected, endurance time declined as the contraction level increased. Plantarflexing responses presented a higher variation from subject to subject than for dorsiflexing. Inter-subject variability primarily seemed to involve a change in the shape of the endurance curve rather than a shift of the curve. When the data were pooled, the exponential curve had parameters similar to the average of the individual fits. Human ankle dorsiflexion and plantarflexion endurance times as a function of level of contraction were found to be similar under the present experimental conditions.

Differentiation of immortalized epithelial cells derived from cystic fibrosis airway submucosal glands

Cystic fibrosis (CF) involves abnormalities in mucus production and secretion of the airway. Studies of the regulation of airway mucin production and secretion has been difficult due to the lack of in vitro models of the airway epithelial cells which express functional differentiation. Because the majority of the mucin in the airway is apparently produced by the submucosal glands, we have focused our attention on the development of cell culture models of human airway submucosal glands. This report describes the propagation of CF airway submucosal gland epithelial cells which continue to express mucin production. The CF bronchus was obtained from a 31-yr-old patient who received a double lung transplant. The glands were dissected out and primary cultures prepared by the explant/outgrowth procedure. The cells were immortalized by infection with Ad12-SV40 hybrid virus. The cultures are maintained in serum-free keratinocyte basal medium supplemented with insulin (5 micrograms/ml), hydrocortisone (0.5 microgram/ml), epidermal growth factor (10 ng/ml), bovine pituitary extract (25 micrograms/ml), and antibiotics. Cultures were passaged using 0.125% trypsin in Ca+2 and Mg(+2)-free Hanks', balanced salt solution. Polymerase chain reaction (PCR) analysis demonstrated that the cells were homozygous for the delta F508 mutation. Morphologic observations showed that the cells were epithelial and were interconnected by sparsely distributed desmosomes. Their cytoplasm contained secretory-type structures including abundant Golgi, rough endoplasmic reticulum, and secretory vesicles. Immunofluorescent studies determined that all cells were positive for cytokeratins, mucin glycoconjugates, and cystic fibrosis transmembrane conductance regulator. The cultures secreted substantial amounts of mucin glycoproteins and expressed the MUC-2 mucin gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in secretory profiles of epithelial cell cultures derived from human tracheal and bronchial mucosa and submucosal glands

The respiratory tract contains macromolecules produced by various epithelia including tracheal and bronchial mucosa and submucosal glands. The objectives of this study were to elucidate and compare the growth and secretory profiles of epithelial cell cultures derived from the human tracheal (TC) and bronchial mucosa (BC) and submucosal glands (GC). Most experiments were done on third to fourth passage cultures. Secretory glycoconjugates were characterized by a combination of gel filtration and anion-exchange chromatography after enzymic digestion with hyaluronidase of [3H]glucosamine and [35S]sulphate incorporated glycoconjugates secreted into the culture medium. Intracellular mucin-like glycoproteins were characterized by immunohistochemical staining with a human monoclonal respiratory mucin antibody. Results showed that the three cell types exhibited variable growth rates and secretory profiles. Doubling times of GC, BC and TC were 53, 75 and 80 h respectively. Immunocytochemical staining with the mucin antibody demonstrated positive reaction in GC and BC; TC showed no significant reaction. Mucin-like glycoproteins were detected in the spent media of GC and BC whereas TC, under the same conditions, did not produce any detectable amount of the glycoconjugates. Further, the mucin-like materials produced by GC and BC differed in their relative glycosylation and sulphation levels. The production of mucin was independent of substrate and vitamin A as the cultures were propagated on the plastic surfaces and the culture medium lacked vitamin A.

Successful in vitro growth of human respiratory epithelium on a tracheal prosthesis

Reconstruction of tracheal defects may be necessary following trauma or oncologic surgery. Defects up to 8 cm can often be repaired using end-to-end anastomosis. Use of a tracheal prosthesis for larger defects has been complicated by recurrent stenosis and infection. Recent animal studies, utilizing a Dacron polyurethane prosthesis suggest that problems with anastomotic stenosis and infection can be controlled. Problems with a central stenosis within the prosthesis persist when used for defects greater than 6 cm. Establishment of a confluent lining of respiratory epithelium is believed to be necessary for successful prosthetic tracheal reconstruction. Using cell culture techniques, we report the first successful seeding and growth of human respiratory epithelium onto a Dacron polyurethane tracheal prosthesis.

Characterization of epithelial cell cultures derived from human tracheal glands

Cultures of normal human tracheal gland epithelial cells that exhibit functional differentiation have been propagated in serum-free medium supplemented with insulin (5 micrograms/ml), epidermal growth factor (10 ng/ml), hydrocortisone (0.5 micrograms/ml), and bovine pituitary extract (25 micrograms/ml). The cells retain many characteristics of epithelial cells including microvilli on cell surfaces, desmosomes between cells, and tonofilaments in the cytoplasm. In addition, they exhibit keratin-positive titers and react positively with Peanut agglutinin, which is specific for the disaccharide beta-D-galactose-(1----3)N-acetyl D-galactosamine, a major component of mucin glycoprotein. The cells also exhibit normal Cl- channel activity which was enhanced by the cAMP agonist Forskolin. The major component of the cellular secretion was hyaluronic acid; approximately 10% of the void volume material was resistant to hyaluronidase and may contain material similar to mucin glycoprotein. Some of the cell cultures have been maintained in serum-free conditions for 6 to 7 passages. This model will be important to study regulation of ion-channel activities and mucous glycoprotein secretion and to compare such regulations with the tracheal mucosal epithelial cells already established.

Frequency characteristics of signals and instrumentation: implication for EMG biofeedback studies

Signals can be analyzed in either the time or frequency domain. In the time domain, the analysis consists of manipulating and measuring one or more characteristics of the signal that may vary with time. One can, for instance, rectify a signal, filter it, calculate its mean value, display the histogram of its amplitude, and so forth. Frequency analysis is less well understood because it requires a lengthy mathematical treatment most easily done by computer. However, it gives exclusive information on a signal. For instance, when the frequency content of a signal is known, it is easy to specify which characteristics an amplifier must have in order to amplify the signal without distortion, or to set the cutoff frequencies of filters to eliminate noise. Also, in many circumstances, frequency spectra are more easily interpreted than the original raw data. Such is the case with the EMG where the random aspect of the signal makes some form of processing (i.e., rectification, filtering, etc.) necessary, but not always as meaningful as we would like. Thus we present here the principal characteristics of frequency analysis, and discuss its usefulness in analyzing EMG signals and its application to biofeedback, clinical practice, and research.

EMG power spectrum as a measure of muscular fatigue at different levels of contraction

The shift in the power spectrum resulting from a 5-7 min fatigue-inducing effort followed by a 1-2 min recovery period of two elbow flexors, the biceps brachii (BB) and the brachio-radialis (BR), was assessed using two variables, the mean frequency Fm and the median or central frequency Fmd. These two variables were calculated in pre- and post-fatigue conditions and following a brief recovery, at four levels, namely 20, 40, 60 and 80 per cent of maximum voluntary contraction (MVC). These were taken from a ramped isometric effort that is from 0 to 100 per cent MVC. The EMG activity of the two flexors was recorded with bipolar surface electrodes from a group of ten volunteers. Following muscle fatigue, induced with a maintained 60 per cent MVC isometric contraction, a statistically significant (p less than 0.05) shift towards the lower frequencies was observed for both Fm and Fmd for both muscles. Following a brief recovery, a shift towards the pre-fatigue higher frequencies was statistically significant (p less than 0.05). These two synergists responded to muscle fatigue and recovery similarly, as they both demonstrated parallel shifts in power spectrum. The power spectrum is consequently a reliable measure of muscular fatigue. It is also complementary to the net articular moment results.

A study of soma isopotentiality in Aplysia neurons

Soma isopotentiality in small, approximately spherical nerve cells during an action potential results in the total transmembrane current being proportional to the first time derivative of the membrane potential. The analytical results of earlier workers are used to obtain quantitative estimates of the deviations in soma isopotentiality to be expected when cells R2 and R15 in the abdominal ganglion of Aplysia californica are subjected to subthreshold stimulation. The deviations in isopotentiality during an action potential are determined experimentally in a small number of cells by noting the instantaneous potential difference between two widely spaced microelectrodes inserted in the cell soma. These analytical and experimental investigations showed that the soma of the endogenously active cell R15 could be considered isopotential both for subthreshold stimulation as well as during an action potential. On the other hand, a clear deviation from isopotentiality was observed in the silent cell R2 where activity was elicited by antidromic stimulation of the axon. Accordingly for the spontaneous action potentials observed in cell R15, a phase–plane diagram transforms into a current–voltage plot and is discussed from this point of view. The lack of soma isopotentiality for antidromic stimulation is presumably due to differing contributions of the triggering axon spike at the two separate microelectrode locations.

Characteristics of pacemaker oscillations in Aplysia neurons

Slow membrane potential oscillations of 5–50 mV in amplitude were unmasked in "bursting" neurons of Aplysia, following treatment with tetrodotoxin. These oscillations were sensitive to changes in membrane polarization; both the amplitude and period decreased with depolarization and increased with hyperpolarization. The oscillations could be blocked by strong depolarization or hyperpolarization, and the two critical levels or stable states corresponded approximately to −30 mV and −70 mV. The bursting discharge of the intact neuron appears to be caused by such an oscillation, but the effects of spike activity on the oscillator mechanism are still largely unknown.