GIDEON (Global Investigation of therapeutic DEcisions in hepatocellular carcinoma and Of its treatment with sorafeNib): second interim analysis.

BACKGROUND: GIDEON (Global Investigation of therapeutic DEcisions in hepatocellular carcinoma [HCC] and Of its treatment with sorafeNib) is a global, prospective, non-interventional study undertaken to evaluate the safety of sorafenib in patients with unresectable HCC in real-life practice, including Child-Pugh B patients who were excluded from clinical trials. METHODS: Patients with unresectable HCC, for whom the decision to treat with sorafenib, based on the approved label and prescribing guidelines, had been taken by their physician, were eligible for inclusion. Demographic data and disease/medical history were recorded at entry. Sorafenib dosing and adverse events (AEs) were collected at follow-up visits. The second interim analysis was undertaken when ~1500 treated patients were followed up for ≥ 4 months. RESULTS: Of the 1571 patients evaluable for safety, 61% had Child-Pugh A status and 23% Child-Pugh B. The majority of patients (74%) received the approved 800 mg initial sorafenib dose, regardless of Child-Pugh status; however, median duration of therapy was shorter in Child-Pugh B patients. The majority of drug-related AEs were grade 1 or 2, and the most commonly reported were consistent with previous reports. The incidence and nature of drug-related AEs were broadly similar across Child-Pugh, Barcelona Clinic Liver Cancer (BCLC) and initial dosing subgroups, and consistent with the overall population. CONCLUSIONS: Consistent with the first interim analysis, overall safety profile and dosing strategy are similar across Child-Pugh subgroups. Safety findings also appear comparable irrespective of initial sorafenib dose or BCLC stage. Final analyses in > 3000 patients are ongoing.

Inhibition of transforming growth factor (TGF)-beta1-induced extracellular matrix with a novel inhibitor of the TGF-beta type I receptor kinase activity: SB-431542.

Transforming growth factor beta1 (TGF-beta1) is a potent fibrotic factor responsible for the synthesis of extracellular matrix. TGF-beta1 acts through the TGF-beta type I and type II receptors to activate intracellular mediators, such as Smad proteins, the p38 mitogen-activated protein kinase (MAPK), and the extracellular signal-regulated kinase pathway. We expressed the kinase domain of the TGF-beta type I receptor [activin receptor-like kinase (ALK)5] and the substrate, Smad3, and determined that SB-431542 is a selective inhibitor of Smad3 phosphorylation with an IC50 of 94 nM. It inhibited TGF-beta1-induced nuclear Smad3 localization. The p38 mitogen-activated protein kinase inhibitors SB-203580 and SB-202190 also inhibit phosphorylation of Smad3 by ALK5 with IC50 values of 6 and 3 microM, respectively. This suggests that these p38 MAPK inhibitors must be used at concentrations of less than 10 microM to selectively address p38 MAPK mechanisms. However, the p38 MAPK inhibitor SB-242235 did not inhibit ALK5. To evaluate the relative contribution of Smad signaling and p38 MAPK signaling in TGF-beta1-induced matrix production, the effect of SB-431542 was compared with that of SB-242235 in renal epithelial carcinoma A498 cells. All compounds inhibited TGF-beta1-induced fibronectin (FN) mRNA, indicating that FN synthesis is mediated in part via the p38 MAPK pathway. In contrast, SB-431542, but not the selective p38 MAPK inhibitor SB-242235, inhibited TGF-beta1-induced collagen Ialpha1 (col Ialpha1). These data indicate that some matrix markers that are stimulated by TGF-beta1 are mediated via the p38 MAPK pathway (i.e., FN), whereas others seem to be activated via ALK5 signaling independent of the p38 MAPK pathway (i.e., col Ialpha1).

Tumorigenicity of four optically active bay-region 3,4-diol 1, 2-epoxides and other derivatives of the nitrogen heterocycle dibenz[c,h]acridine on mouse skin and in newborn mice.

The nitrogen heterocycle dibenz[c,h]acridine (DB[c,h]ACR) and the enantiomers of the diastereomeric pair of bay-region 3,4-diol 1, 2-epoxides as well as other bay-region epoxides and dihydrodiol derivatives of this hydrocarbon have been evaluated for tumorigenicity on mouse skin and in the newborn mouse. On mouse skin, a single topical application of 50 or 200 nmol of compound was followed 10 days later by twice-weekly applications of the tumor promoter 12-O:-tetradecanoylphorbol-13-acetate for 20 weeks. DB[c, h]ACR and the four optically pure, bay-region 3,4-diol-1,2-epoxide isomers all had significant tumor- initiating activity. The isomer with (1R,2S,3S,4R) absolute configuration [(+)-DE-2] was the most active diol epoxide isomer. The (-)-(3R,4R)-dihydrodiol of DB[c, h]ACR, the expected metabolic precursor of the bay-region (+)-DE-2, was 4- to 6-fold more tumorigenic than its corresponding (+)-enantiomer. In tumorigenicity studies in newborn mice, a total dose of 70-175 nmol of DB[c,h]ACR or one of its derivatives was injected i.p. on days 1, 8 and 15 of life, and tumorigenic activity was determined when the mice were 36-39 weeks old. DB[c,h]ACR produced a significant number of pulmonary tumors and also produced hepatic tumors in male mice. Of the four optically active bay-region diol epoxides, only (+)-DE-2 and (+)-DE-1 with (1R,2S,3S,4R) and (1S, 2R,3S,4R) absolute configuration, respectively, produced a significant tumor incidence. At an equivalent dose, the (+)-DE-2 isomer produced several-fold more pulmonary tumors and hepatic tumors than the (+)-DE-1 isomer. The (-)-(3R,4R)-dihydrodiol, metabolic precursor of the bay-region (+)-DE-2, was strongly active and induced an equal number of pulmonary and hepatic tumors as did DB[c,h]ACR. The (+)-(3S,4S) dihydrodiol was less active. The bay-region (+)-(1R,2S)-epoxide of 1,2,3,4-tetrahydro DB[c,h]ACR was strongly tumorigenic in newborn mice whereas its (-)-(1S, 2R)-enantiomer was inactive. This contrasts with the data on mouse skin where both enantiomers had substantial tumorigenic activity. In summary, the bay-region (+)-(1R,2S,3S,4R)-3,4-diol 1,2-epoxide of DB[c,h]ACR was the most tumorigenic of the four optically active bay-region diol epoxides of DB[c,h]ACR on mouse skin and in the newborn mouse. These results with a nitrogen heterocycle are similar to earlier data indicating high tumorigenic activity for the R,S,S,R bay-region diol epoxides of several carbocyclic polycyclic aromatic hydrocarbons.

A modified metal-ion affinity chromatography procedure for the purification of histidine-tagged recombinant proteins expressed in Drosophila S2 cells.

We have developed a modified method of immobilized metal-ion affinity chromatography (IMAC) that can be used for the purification of histidine-tagged proteins from conditioned medium containing free copper ions. Classical methods of IMAC purification, using resins such as Ni-NTA, have proven inefficient for this type of purification and require multiple steps due to the interference of divalent copper ions with the binding of His-tagged protein to the charged resin. In contrast, this modified IMAC procedure, using chelating Sepharose instead of Ni-NTA, enables efficient purification from copper-containing medium in a single step. This method appears to rely upon a preferential interaction of protein-copper complexes with immobilized chelating resin. We have utilized this method to purify active, His-tagged murine interleukin 12 from the conditioned medium of Drosophila S2 cells coexpressing recombinant p40 and His-tagged p35 subunits and for the purification of the extracellular domain of the erythropoietin receptor. This method should be applicable to the purification of a wide variety of His-tagged fusion proteins expressed in Drosophila cells and in other systems where free metal ions are present.

Identification and initial characterization of four novel members of the interleukin-1 family.

Interleukin-1 (IL-1), fibroblast growth factors (FGFs), and their homologues are secreted factors that share a common beta-barrel structure and act on target cells by binding to cell surface receptors with immunoglobulin-like folds in their extracellular domain. While numerous members of the FGF family have been discovered, the IL-1 family has remained small and outnumbered by IL-1 receptor homologues. From expressed sequence tag data base searches, we have now identified four additional IL-1 homologues, IL-1H1, IL-1H2, IL-1H3, and IL-1H4. Like most other IL-1/FGFs, these proteins do not contain a hydrophobic leader sequence. IL-1H4 has a propeptide sequence, while IL-1H1, IL-1H2, and IL-1H3 encode only the mature protein. Circular dichroism spectra and thermal stability analysis suggest that IL-1H1 folds similarly to IL-1ra. The novel homologues are not widely expressed in mammals. IL-1H1 is constitutively expressed only in placenta and the squamous epithelium of the esophagus. However, IL-1H1 could be induced in vitro in keratinocytes by interferon-gamma and tumor necrosis factor-alpha and in vivo via a contact hypersensitivity reaction or herpes simplex virus infection. This suggests that IL-1H1 may be involved in pathogenesis of immune mediated disease processes. The addition of four novel IL-1 homologues suggests that the IL-1 family is significantly larger than previously thought.

The structure of ribonuclease P protein from Staphylococcus aureus reveals a unique binding site for single-stranded RNA.

Ribonuclease P (RNaseP) catalyses the removal of the 5'-leader sequence from pre-tRNA to produce the mature 5' terminus. The prokaryotic RNaseP holoenzyme consists of a catalytic RNA component and a protein subunit (RNaseP protein), which plays an auxiliary but essential role in vivo by binding to the 5'-leader sequence and broadening the substrate specificity of the ribozyme. We determined the three-dimensional high-resolution structure of the RNaseP protein from Staphylococcus aureus (117 amino acid residues) by nuclear magnetic resonance (NMR) spectroscopy in solution. The protein has an alphabeta-fold, similar to the ribonucleoprotein domain. We used small nucleic acid molecules as a model for the 5'-leader sequence to probe the propensity for generic single-stranded RNA binding on the protein surface. The NMR results reveal a contiguous interaction site, which is identical with the previously identified leader sequence binding site in RNaseP holoenzyme. The conserved arginine-rich motif does not bind single-stranded RNA. It is likely that this peptide segment binds selectively to double-stranded sections of P RNA, which are conformationally more rigid. Given the essentiality of RNaseP for the viability of the organism, knowledge of the S. aureus protein structure and insight into its interaction with RNA will help us to develop RNaseP and RNaseP protein as targets for novel antibiotics against this pathogen.

The proximate carcinogen trans-3,4-dihydroxy-3,4-dihydro-dibenz[c,h]acridine is oxidized stereoselectively and regioselectively by cytochrome 1A1, epoxide hydrolase and hepatic microsomes from 3-methylcholanthrene-treated rats.

Metabolism of the proximate carcinogen trans-3,4-dihydroxy-3,4-dihydrodibenz[c,h]acridine has been examined with rat liver enzymes. The dihydrodiol is metabolized at a rate of 2.4 nmol/nmol of cytochrome P450 1A1/min with microsomes from 3-methylcholanthrene-treated rats, a rate more than 10-fold higher than that observed with microsomes from control or phenobarbital-treated rats. Major metabolises consisted of a diastereomeric pair of bis-dihydrodiols (68-83%), where the new dihydrodiol group has been introduced at the 8,9-position, tetraols derived from bay region 3,4-diol-1,2-epoxides (15-23%), and a small amount of a phenolic dihydrodiol(s) where the new hydroxy group is at the 8,9-position of the substrate. A highly purified monooxygenase system reconstituted with cytochrome P450 1A1 and epoxide hydrolase (17 nmol of metabolites/nmol of cytochrome P450 1A1/min) gave a metabolite profile very similar to that observed with liver microsomes from 3-methylcholanthrene-treated rats. Study of the stereoselectivity of these microsomes established that the (+)-(3S,4S)-dihydrodiol gave mainly the diol epoxide-1 diastereomer, in which the benzylic 4-hydroxyl group and epoxide oxygen are cis. The (-)-(3R,4R)-dihydrodiol gave mainly diol epoxide-2 where these same groups are trans. The major enantiomers of the diastereomeric bis-dihydrodiols are shown to have the same absolute configuration at the 8,9-position. Correlations of circular dichroism spectra suggest this configuration to be (8R,9R). The (8R,9S)-oxide may be their common precursor.

Production, purification and characterization of non-myristylated human T-cell protein tyrosine kinase in a baculovirus expression system.

A non-myristylated form (LCK M) of the human T-lymphocyte-specific protein tyrosine kinase (LCK) was produced at high levels in a baculovirus expression system (BVES) using two strategies. First, LCK M was produced by direct expression of a Gly2 --> Ala mutant of LCK. Second, LCK was produced as a glutathione S-transferase (GST) fusion, and LCK M was derived from the fusion protein by cleavage with thrombin. Both recombinant proteins (re-proteins) were produced at 5% of the total protein of infected Spodoptera frugiperda (Sf9) cells and were purified to >95% homogeneity. The enzymatic properties of the re-proteins and their inhibition by protein kinase inhibitors were comparable to the native enzyme (LCK N) derived from Jurkat cells and wild-type LCK derived from the BVES. The high production levels will facilitate the recovery of large quantities of re-protein for use in biochemical and biophysical studies.

Testing knowledge of human gross anatomy in medical school: an applied contextual-learning theory method.

The traditional gross anatomy laboratory experience, with modifications in evaluations that we outline later, meets the criteria of contextual-learning theory, expands the repertoire of core objectives we identify for our students, and may increase the likelihood of cognitive permanence of anatomical data. Our subjects included approximately 54 first-year medical students from each of three sequential class years (1996, 1997, 1998). As an alternative to more typical written and practical exams, examinations in a major portion of our gross anatomy program consist of two approximately 30 minute oral expositions by each student to his or her peers and a faculty member. Students demonstrate specific detail on cadaver, x-ray, cross sections, or a model. Clinical applications, spatial relationships, nomenclature, and functions are strongly emphasized. The results of this teaching approach to the utilization of anatomical knowledge in clinical situations requires further assessment: however, new attributes have been afforded our students with implementation of the present program: First, students learn anatomical detail equally well as the students of the more traditional system (based on board exam results). Second, students who completed the program indicate that this approach provides a useful simulation of what is expected later in their training. Third, students gradually gain confidence in verbal presentation, they demonstrate cognitive synthesis of separate conceptual issues, they retain information, and they are quite visibly more enthusiastic about anatomy and its importance in medicine. Our program demonstrates that the learning of applicable human anatomy is facilitated in a contextual-learning environment. Moreover, by learning anatomy in this way, other equally beneficial attributes are afforded the medical student, including, but not limited to, increases in communication skills, confidence in verbal presentation, synthesis of anatomical concepts, appreciation of the clinical importance of anatomy, and the general development of professionalism.

In vivo and in vitro studies on the neurotoxic potential of 6-hydroxydopamine analogs.

In an attempt to determine which physical and biological properties could best be correlated with neurotoxic potential, seven analogs of 1-(2,4,5-trihydroxyphenyl)-2-aminoethane (1), better known as 6-hydroxydopamine, were synthesized and compared to 1 in a variety of ways both in vivo and in vitro. The analogs, in combination with the standard 1, include all eight of the 2,4,5-trisubstituted-phenyl derivatives of phenethylamine and alpha-methylphenethylamine in which the substitution is of the trihydroxy or aminodihydroxy form. Low (60 nmol) and high (300 nmol) intracerebroventricular doses of all analogs produced long-term (7 day) reduction of mouse whole brain norepinephrine (NE) and lesser depletions of dopamine (DA), and effects on serotonin were varied. The analog 1-(5-amino-2,4-dihydroxyphenyl)-2-aminopropane (8) was both more complete and more selective than the standard 1 in depleting NE. Using a histofluorometric glyoxylic acid method and Fink-Heimer silver degeneration stain, it was determined that overt neural degeneration was produced by 8. In vitro, the ease of oxidation of the eight analogs was found to be represented by a formal potential range of -130 to -212 mV vs SCE. However, there was no obvious relationship between ease of oxidation and the extent of monoamine depletion from mouse brain. Using kinetic analysis of synaptosomal accumulation of [3H]NE and [3H]DA, it was found that the standard 1 is more potent in its interaction with the DA uptake site (Ki = 12 +/- 0 microM) than the NE uptake site (Ki = 51 +/- 1 microM). A correlation analysis was used to determine that differences in NE and DA depletion by each analog could not be explained by differences in potency for in vitro uptake blockade. However, there was a correlation between the Ki for [3H]NE uptake blockade and the EC50 for synaptosomal release of preloaded [3H]NE for the eight analogs (R2 = 0.96; for log:log plot, R2 = 0.54), indicating that the results for these two in vitro tests both reflect interaction with the same NE neuronal membrane transport site. A similar correlation between Ki and EC50 was shown for all eight analogs using [3H]DA (R2 = 0.92; for log:log plot, R2 = 0.52), indicating interaction with the same DA neuronal membrane transport site. These findings demonstrate that there is no single property that can account for selectivity of action and/or potency of catecholamine neurotoxins related to 6-hydroxydopamine.

Damnacanthal is a highly potent, selective inhibitor of p56lck tyrosine kinase activity.

Damnacanthal, an anthraquinone isolated from a plant extract, was found to be a potent, selective inhibitor of p56lck tyrosine kinase activity. The structure, potency, and selectivity of damnacanthal were confirmed by independent synthesis and testing. Damnacanthal exhibited an IC50 of 17 nM for inhibition of p56lck autophosphorylation and an IC50 of 620 nM for phosphorylation of an exogenous peptide by p56lck. Damnacanthal had > 100-fold selectivity for p56lck over the serine/threonine kinases, protein kinase A and protein kinase C, and > 40-fold selectivity for p56lck over four receptor tyrosine kinases. It also demonstrated modest (7-20-fold), but highly statistically significant, selectivity for p56lck over the homologous enzymes p60src and p59fyn. Mechanistic studies demonstrated that damnacanthal was competitive with the peptide binding site, but mixed noncompetitive with the ATP site. Although damnacanthal contains a potentially reactive aldehyde moiety, equilibrium dialysis experiments demonstrated that significant amine formation between damnacanthal and amines occurred only at high concentrations of reactants. However, damnacanthal appeared to bind nonspecifically to membrane lipids and was not active in whole cell tyrosine kinase assays. Damnacanthal is the most potent, selective inhibitor of p56lck tyrosine kinase activity described to date and may represent the starting point for the identification of novel, selective inhibitors of p56lck which are active in whole cell as well as in cell-free systems.

Hydrophobic interactions and the design of receptor mimetic peptides.

The possibility that hydrophobic interactions may be used as a basis for the design of receptor mimetic peptides for small peptide hormones that lack the potential to adopt amphiphilic secondary structures was tested by designing and characterizing receptor mimetic peptides for gamma-endorphin. The receptor mimetic peptides were designed to exhibit a pattern of hydrophobic surfaces in an antiparallel orientation matching that of the peptide hormone in an extended conformation. An ELISA-based assay was used to determine the relative binding affinities of receptor mimetic peptides, control peptides and antisense peptides to gamma-endorphin immobilized on a surface. The inhibition constant for the best gamma-endorphin receptor mimetic peptide was 1.6 microM. No binding was detected for scrambled control peptides or the antisense-derived peptide mimetic to the limit of their respective solubilities. Sera from rabbits immunized with a gamma-endorphin receptor mimetic peptide were used to immunopurify the ligand-binding domain of the human opiate receptor and were cross-reactive with purified bovine opiate receptor. These results suggest that patterns of hydrophobicity can provide a rational basis for designing receptor mimetic peptides and may provide an explanation for the ability of some antisense peptides to bind to their cognate hormones and to elicit antibodies cross-reactive with hormone receptors.

p56lck interactions accelerate autophosphorylation and enhance activity toward exogenous substrates.

p56lck, which is a lymphoid-restricted tyrosine kinase, plays a significant role both in activation of mature T lymphocytes and in T cell development. Recombinant human p56lck was expressed in a baculovirus system and purified to > 95% purity. Purified recombinant p56lck was found to have enzymatic characteristics indistinguishable from those of the native enzyme expressed in the Jurkat human T lymphocytic cell line. The comparisons of recombinant and native p56lck were performed using an assay in which the enzyme was immobilized with antibodies onto the wells of a microtiter plate, enabling in situ purification of the native enzyme. Further characterization of the purified recombinant p56lck revealed significantly different enzyme concentration curves for peptide phosphorylation by immobilized and soluble p56lck. In particular, there was very low activity at low concentrations of enzyme assayed in solution. The activity at low enzyme concentrations could be substantially increased by preincubation of high concentrations of enzyme with ATP prior to dilution for the peptide phosphorylation reaction. We examined the relationship between autophosphorylation and activation for peptide phosphorylation. As for peptide phosphorylation, nonlinear enzyme concentration curves were also observed for autophosphorylation in solution, with very low levels of autophosphorylation at low enzyme concentrations. There was a correlation between the enzyme concentration dependency for autophosphorylation and for preincubation with ATP for maximal enhancement of subsequent peptide phosphorylation. The results suggest that autophosphorylation activates p56lck for phosphorylation of exogenous substrates and that high enzyme concentrations accelerate intermolecular autophosphorylation and enzyme activation.

Post-traumatic syringomyelia.

Post-traumatic syringomyelia was previously thought to be an infrequent but serious sequel to spinal cord injury. Clinical and CT studies have shown an incidence of between 1% and 5%, but more recently MRI has suggested an incidence of up to 22%. Twenty spinal cords have been examined after death from two days to 43 years after injury. Four had syrinxes, 20% of the series, approaching the incidence found by MRI. The acute and chronic pathological changes after trauma are described. Post-traumatic syringomyelia seems to develop from cores of necrotic tissue (myelomalacic cores) rather than lysis of haematoma. The mechanism of extension of syrinxes remains unexplained.

Post-acute rehabilitation outcome: relationship to case-management techniques and strategy.

Successful outcome for the traumatically brain-injured (TBI) patient is dependent on both a productive clinical therapy program and an effective case-management strategy by the carrier. This retrospective study focuses on identifying those case-management techniques which contributed to improvement in the disability, living, and occupational status of patients in a post-acute rehabilitation program. Statistical analysis indicated a positive relationship between two case-management factors and improved patient outcome. Additional analysis demonstrated predictive qualities of specific admission data for patient program cost. A review of these case-management techniques and their impact on discharge disability, living, and occupational status will be discussed.

[Freeze preservation of swine corneas with combinations of intra- and extracellular cryoprotective agents]. / Gefrierkonservierung von Schweinehornhäuten mit Kombinationen von intra- und extrazellulären Kryoprotektoren.

Clinically employed methods of corneal cryopreservation usually use the intracellular cryoprotectant dimethyl sulfoxide (DMSO). However, it has been demonstrated that extracellular cryoprotectants such as chondroitin sulfate (ChS) also display effective cryoprotection. The purpose of our study was to investigate the effect of combinations of intra- and extracellular cryoprotectants in corneal cryopreservation. Porcine corneas were cryopreserved in a cryopreservation medium consisting of MEM-medium containing 20% fetal calf serum and 2% chondroitin sulfate. The medium was varied by the addition of 2%, 4% and 8% DMSO. Sixty corneas were cryopreserved at -196 degrees C and thawed at 37 degrees C in a water bath. Morphometric evaluation was not performed directly after thawing but after a 24-h storage period in organ culture. Cryopreservation in medium without DMSO revealed the best results concerning endothelial cell density (2581 cells/mm2). Addition of 2% or 4% DMSO revealed no significant changes in endothelial cell density. Addition of 8% DMSO, however, resulted in a significant decrease (1312 +/- 319 cells/mm2) combined with a significantly higher amount of necrotic areas in the central corneal surface. We conclude that combining intra- and extracellular cryoprotectants does not enhance endothelial cell density after corneal cryopreservation. Higher concentrations of DMSO added to the cryopreservation medium appear to have a negative impact on endothelial cell viability.

Sixteen S-squared over D-squared: a relation for crude sample size estimates.

I suggest for memorization an equation for calculating approximate sample size requirements intended only for a specific set of values (80 per cent power for a two-tailed alpha = 0.05 test) which seems to occur often in biopharmaceutical research. After presenting the formula in terms of variance estimate s2 and effect size d, I derive a few alternative forms and then discuss the accuracy of the approximation and other properties as well as examples of its use.

Electromyographic evidence of a multiple motor system: implications for apraxia.

Geschwind (1975) postulated that a multiple motor system accounts for a discrepancy in apraxias in response to commands for truncal and limb movements. Kuypers (1968) provided experimental evidence of a multiple motor system in primates. We present evidence of this multiple motor system in the form of Fourier-transformed electromyographic data in humans of the predominantly short duration motor units for discrete control in hand musculature and the predominantly longer duration motor units in the truncal musculature. Furthermore, the right and left erector spinae muscles had different Fourier-transformed electromyographic data which, in our opinion, represent the medial motor system used by apraxias.

Electromyographic study of sternocleidomastoid and scalene muscles in tetraplegic subjects during respiration.

An electromyographic investigation of inspiratory respiratory muscles was carried out in six tetraplegic and two normal subjects using needle electrodes. When the normal subjects were using tidal breathing there was no activity present. In the majority of tetraplegic subjects, activity was present in the scalene muscle during tidal breathing. This activity became more marked during deep inspiration. The muscles were hypertrophied and these muscles filled an important respiratory role.