Antibody blockade of activin type II receptors preserves skeletal muscle mass and enhances fat loss during GLP-1 receptor agonism

OBJECTIVE

Glucagon-like peptide 1 (GLP-1) receptor agonists reduce food intake, producing remarkable weight loss in overweight and obese individuals. While much of this weight loss is fat mass, there is also a loss of lean mass, similar to other approaches that induce calorie deficit. Targeting signaling pathways that regulate skeletal muscle hypertrophy is a promising avenue to preserve lean mass and modulate body composition. Myostatin and Activin A are TGFβ-like ligands that signal via the activin type II receptors (ActRII) to antagonize muscle growth. Pre-clinical and clinical studies demonstrate that ActRII blockade induces skeletal muscle hypertrophy and reduces fat mass. In this manuscript, we test the hypothesis that combined ActRII blockade and GLP-1 receptor agonism will preserve muscle mass, leading to improvements in skeletomuscular and metabolic function and enhanced fat loss.

METHODS

In this study, we explore the therapeutic potential of bimagrumab, a monoclonal antibody against ActRII, to modify body composition alone and during weight loss induced by GLP-1 receptor agonist semaglutide in diet-induced obese mice. Mechanistically, we define the specific role of the anabolic kinase Akt in mediating the hypertrophic muscle effects of ActRII inhibition in vivo.

RESULTS

Treatment of obese mice with bimagrumab induced a ∼10 % increase in lean mass while simultaneously decreasing fat mass. Daily treatment of obese mice with semaglutide potently decreased body weight; this included a significant decrease in both muscle and fat mass. Combination treatment with bimagrumab and semaglutide led to superior fat mass loss while simultaneously preserving lean mass despite reduced food intake. Treatment with both drugs was associated with improved metabolic outcomes, and increased lean mass was associated with improved exercise performance. Deletion of both Akt isoforms in skeletal muscle modestly reduced, but did not prevent, muscle hypertrophy driven by ActRII inhibition.

CONCLUSIONS

Collectively, these data demonstrate that blockade of ActRII signaling improves body composition and metabolic parameters during calorie deficit driven by GLP-1 receptor agonism and demonstrate the existence of Akt-independent pathways supporting muscle hypertrophy in the absence of ActRII signaling.

Activation of Liver mTORC1 Protects Against NASH via Dual Regulation of VLDL-TAG Secretion and De Novo Lipogenesis

BACKGROUND & AIMS

Dysregulation of liver lipid metabolism is associated with the development and progression of nonalcoholic fatty liver disease, a spectrum of liver diseases including nonalcoholic steatohepatitis (NASH). In the liver, insulin controls lipid homeostasis by increasing triglyceride (TAG) synthesis, suppressing fatty acid oxidation, and enhancing TAG export via very low-density lipoproteins. Downstream of insulin signaling, the mechanistic target of rapamycin complex 1 (mTORC1), is a key regulator of lipid metabolism. Here, we define the role of hepatic mTORC1 activity in mouse models of NASH and investigate the mTORC1-dependent mechanisms responsible for protection against liver damage in NASH.

METHODS

Utilizing 2 rodent NASH-promoting diets, we demonstrate that hepatic mTORC1 activity was reduced in mice with NASH, whereas under conditions of insulin resistance and benign fatty liver, mTORC1 activity was elevated. To test the beneficial effects of hepatic mTORC1 activation in mouse models of NASH, we employed an acute, liver-specific knockout model of TSC1 (L-TSC-KO), a negative regulator of mTORC1.

RESULTS

L-TSC-KO mice are protected from and have improved markers of NASH including reduced steatosis, decreased circulating transaminases, and reduced expression of inflammation and fibrosis genes. Mechanistically, protection from hepatic inflammation and fibrosis by constitutive mTORC1 activity occurred via promotion of the phosphatidylcholine synthesizing enzyme, CCTα, and enhanced very low-density lipoprotein-triglyceride export. Additionally, activation of mTORC1 protected from hepatic steatosis via negative feedback of the mTORC2-AKT-FOXO-SREBP1c lipogenesis axis.

CONCLUSIONS

Collectively, this study identifies a protective role for liver mTORC1 signaling in the initiation and progression of NASH in mice via dual control of lipid export and synthesis.

AKT controls protein synthesis and oxidative metabolism via combined mTORC1 and FOXO1 signalling to govern muscle physiology

BACKGROUND

Skeletomuscular diseases result in significant muscle loss and decreased performance, paralleled by a loss in mitochondrial and oxidative capacity. Insulin and insulin-like growth factor-1 (IGF-1) are two potent anabolic hormones that activate a host of signalling intermediates including the serine/threonine kinase AKT to influence skeletal muscle physiology. Defective AKT signalling is associated with muscle pathology, including cachexia, sarcopenia, and disuse; however, the mechanistic underpinnings remain unresolved.

METHODS

To elucidate the role of AKT signalling in muscle mass and physiology, we generated both congenital and inducible mouse models of skeletal muscle-specific AKT deficiency. To understand the downstream mechanisms mediating AKT's effects on muscle biology, we generated mice lacking AKT1/2 and FOXO1 (M-AKTFOXO1TKO and M-indAKTFOXO1TKO) to inhibit downstream FOXO1 signalling, AKT1/2 and TSC1 (M-AKTTSCTKO and M-indAKTTSCTKO) to activate mTORC1, and AKT1/2, FOXO1, and TSC1 (M-QKO and M-indQKO) to simultaneously activate mTORC1 and inhibit FOXO1 in AKT-deficient skeletal muscle. Muscle proteostasis and physiology were assessed using multiple assays including metabolic labelling, mitochondrial function, fibre typing, ex vivo physiology, and exercise performance.

RESULTS

Here, we show that genetic ablation of skeletal muscle AKT signalling resulted in decreased muscle mass and a loss of oxidative metabolism and muscle performance. Specifically, deletion of muscle AKT activity during development or in adult mice resulted in a significant reduction in muscle growth by 30-40% (P  < 0.0001; n = 12-20) and 15% (P < 0.01 and P < 0.0001; n = 20-30), respectively. Interestingly, this reduction in muscle mass was primarily due to an ~40% reduction in protein synthesis in both M-AKTDKO and M-indAKTDKO muscles (P < 0.05 and P < 0.01; n = 12-20) without significant changes in proteolysis or autophagy. Moreover, a significant reduction in oxidative capacity was observed in both M-AKTDKO (P < 0.05, P < 0.01 and P < 0.001; n = 5-12) and M-indAKTDKO (P < 0.05 and P < 0.01; n = 4). Mechanistically, activation and inhibition of mTORC1/FOXO1, respectively, but neither alone, were sufficient to restore protein synthesis, muscle oxidative capacity, and muscle function in the absence of AKT in vivo. In a mouse model of disuse-induced muscle loss, simultaneous activation of mTORC1 and inhibition of FOXO1 preserved muscle mass following immobilization (~5-10% reduction in casted M-indFOXO1TSCDKO muscles vs. ~30-40% casted M-indControl muscles, P < 0.05 and P < 0.0001; n = 8-16).

CONCLUSIONS

Collectively, this study provides novel insights into the AKT-dependent mechanisms that underlie muscle protein homeostasis, function, and metabolism in both normal physiology and disuse-induced muscle wasting.

Physiological Changes to the Cardiovascular System at High Altitude and Its Effects on Cardiovascular Disease

Riley, Callum James, and Matthew Gavin. Physiological changes to the cardiovascular system at high altitude and its effects on cardiovascular disease. High Alt Med Biol. 18:102-113, 2017.-The physiological changes to the cardiovascular system in response to the high altitude environment are well understood. More recently, we have begun to understand how these changes may affect and cause detriment to cardiovascular disease. In addition to this, the increasing availability of altitude simulation has dramatically improved our understanding of the physiology of high altitude. This has allowed further study on the effect of altitude in those with cardiovascular disease in a safe and controlled environment as well as in healthy individuals. Using a thorough PubMed search, this review aims to integrate recent advances in cardiovascular physiology at altitude with previous understanding, as well as its potential implications on cardiovascular disease. Altogether, it was found that the changes at altitude to cardiovascular physiology are profound enough to have a noteworthy effect on many forms of cardiovascular disease. While often asymptomatic, there is some risk in high altitude exposure for individuals with certain cardiovascular diseases. Although controlled research in patients with cardiovascular disease was largely lacking, meaning firm conclusions cannot be drawn, these risks should be a consideration to both the individual and their physician.

Aflibercept in wet AMD beyond the first year of treatment: recommendations by an expert roundtable panel

This paper provides expert recommendations on administration of aflibercept in wet age-related macular degeneration (AMD) after Year 1 (Y1), based on a roundtable discussion held in London, UK in November 2014. The goals of treatment after Y1 are to maintain visual and anatomical gains whilst minimising treatment burden and using resources effectively. The treatment decision should be made at the seventh injection visit (assuming the label has been followed) in Y1, and three approaches are proposed: (a) eyes with active disease on imaging/examination but with stable visual acuity (VA) at the end of Y1 should continue with fixed 8-weekly dosing; (b) eyes with inactive disease on imaging/examination and stable VA should be managed using a 'treat and extend' (T&E) regimen. T&E involves treating and then extending the interval until the next treatment, by 2-week intervals, to a maximum of 12 weeks, provided the disease remains inactive. If there is new evidence of disease activity, treatment is administered and the interval to the next treatment shortened; and (c) if there has been no disease activity for ≥3 consecutive visits, a trial of monitoring without treatment may be appropriate, initiated at the end of Y1 or at any time during Y2. Where possible, VA testing, OCT imaging and injection should be performed at the same visit. The second eye should be monitored to detect fellow eye involvement. In bilateral disease, the re-treatment interval should be driven by the better-seeing eye or, if the VA is similar, the eye with the more active disease.

The effect of 8 or 5 years of denosumab treatment in postmenopausal women with osteoporosis: results from the FREEDOM Extension study

The FREEDOM study and its Extension provide long-term information about the effects of denosumab for the treatment of postmenopausal osteoporosis. Treatment for up to 8 years was associated with persistent reduction of bone turnover, continued increases in bone mineral density, low fracture incidence, and a favorable benefit/risk profile.

INTRODUCTION

This study aims to report the results through year 5 of the FREEDOM Extension study, representing up to 8 years of continued denosumab treatment in postmenopausal women with osteoporosis.

METHODS

Women who completed the 3-year FREEDOM study were eligible to enter the 7-year open-label FREEDOM Extension in which all participants are scheduled to receive denosumab, since placebo assignment was discontinued for ethical reasons. A total of 4550 women enrolled in the Extension (2343 long-term; 2207 cross-over). In this analysis, women in the long-term and cross-over groups received denosumab for up to 8 and 5 years, respectively.

RESULTS

Throughout the Extension, sustained reduction of bone turnover markers (BTMs) was observed in both groups. In the long-term group, mean bone mineral density (BMD) continued to increase significantly at each time point measured, for cumulative 8-year gains of 18.4 and 8.3 % at the lumbar spine and total hip, respectively. In the cross-over group, mean BMD increased significantly from the Extension baseline for 5-year cumulative gains of 13.1 and 6.2 % at the lumbar spine and total hip, respectively. The yearly incidence of new vertebral and nonvertebral fractures remained low in both groups. The incidence of adverse and serious adverse events did not increase over time. Through Extension year 5, eight events of osteonecrosis of the jaw and two events of atypical femoral fracture were confirmed.

CONCLUSIONS

Denosumab treatment for up to 8 years was associated with persistent reductions of BTMs, continued BMD gains, low fracture incidence, and a consistent safety profile.

Defining response to anti-VEGF therapies in neovascular AMD

The introduction of anti-vascular endothelial growth factor (anti-VEGF) has made significant impact on the reduction of the visual loss due to neovascular age-related macular degeneration (n-AMD). There are significant inter-individual differences in response to an anti-VEGF agent, made more complex by the availability of multiple anti-VEGF agents with different molecular configurations. The response to anti-VEGF therapy have been found to be dependent on a variety of factors including patient's age, lesion characteristics, lesion duration, baseline visual acuity (VA) and the presence of particular genotype risk alleles. Furthermore, a proportion of eyes with n-AMD show a decline in acuity or morphology, despite therapy or require very frequent re-treatment. There is currently no consensus as to how to classify optimal response, or lack of it, with these therapies. There is, in particular, confusion over terms such as 'responder status' after treatment for n-AMD, 'tachyphylaxis' and 'recalcitrant' n-AMD. This document aims to provide a consensus on definition/categorisation of the response of n-AMD to anti-VEGF therapies and on the time points at which response to treatment should be determined. Primary response is best determined at 1 month following the last initiation dose, while maintained treatment (secondary) response is determined any time after the 4th visit. In a particular eye, secondary responses do not mirror and cannot be predicted from that in the primary phase. Morphological and functional responses to anti-VEGF treatments, do not necessarily correlate, and may be dissociated in an individual eye. Furthermore, there is a ceiling effect that can negate the currently used functional metrics such as >5 letters improvement when the baseline VA is good (ETDRS>70 letters). It is therefore important to use a combination of both the parameters in determining the response.The following are proposed definitions: optimal (good) response is defined as when there is resolution of fluid (intraretinal fluid; IRF, subretinal fluid; SRF and retinal thickening), and/or improvement of >5 letters, subject to the ceiling effect of good starting VA. Poor response is defined as <25% reduction from the baseline in the central retinal thickness (CRT), with persistent or new IRF, SRF or minimal or change in VA (that is, change in VA of 0+4 letters). Non-response is defined as an increase in fluid (IRF, SRF and CRT), or increasing haemorrhage compared with the baseline and/or loss of >5 letters compared with the baseline or best corrected vision subsequently. Poor or non-response to anti-VEGF may be due to clinical factors including suboptimal dosing than that required by a particular patient, increased dosing intervals, treatment initiation when disease is already at an advanced or chronic stage), cellular mechanisms, lesion type, genetic variation and potential tachyphylaxis); non-clinical factors including poor access to clinics or delayed appointments may also result in poor treatment outcomes. In eyes classified as good responders, treatment should be continued with the same agent when disease activity is present or reactivation occurs following temporary dose holding. In eyes that show partial response, treatment may be continued, although re-evaluation with further imaging may be required to exclude confounding factors. Where there is persistent, unchanging accumulated fluid following three consecutive injections at monthly intervals, treatment may be withheld temporarily, but recommenced with the same or alternative anti-VEGF if the fluid subsequently increases (lesion considered active). Poor or non-response to anti-VEGF treatments requires re-evaluation of diagnosis and if necessary switch to alternative therapies including other anti-VEGF agents and/or with photodynamic therapy (PDT). Idiopathic polypoidal choroidopathy may require treatment with PDT monotherapy or combination with anti-VEGF. A committee comprised of retinal specialists with experience of managing patients with n-AMD similar to that which developed the Royal College of Ophthalmologists Guidelines to Ranibizumab was assembled. Individual aspects of the guidelines were proposed by the committee lead (WMA) based on relevant reference to published evidence base following a search of Medline and circulated to all committee members for discussion before approval or modification. Each draft was modified according to feedback from committee members until unanimous approval was obtained in the final draft. A system for categorising the range of responsiveness of n-AMD lesions to anti-VEGF therapy is proposed. The proposal is based primarily on morphological criteria but functional criteria have been included. Recommendations have been made on when to consider discontinuation of therapy either because of success or futility. These guidelines should help clinical decision-making and may prevent over and/or undertreatment with anti-VEGF therapy.

ANCA associated pauci-immune retinal vasculitis

BACKGROUND

Antinuclear cytoplasmic antibodies (ANCA) are useful diagnostic serological markers for the most common forms of necrotising vasculitis. ANCA associated vasculitides represent distinctive clinicopathological categories--for example, Wegener's granulomatosis, Churg-Strauss syndrome, microscopic polyangiitis, and idiopathic necrotising crescentic glomerulonephritis, collectively known as the small vessel pauci-immune vasculitides.

METHOD

Three cases of ANCA associated pauci-immune retinal vasculitis are described. Their systemic features are described and the clinical significance of ANCA as a diagnostic test in relation to retinal vasculitis discussed.

RESULTS

These three cases represent a spectrum of clinical features associated with retinal vasculitis. Two cases have evolved into clinical recognisable entities as microscopic polyangiitis. Adherence to the international consensus statement on testing and reporting of ANCA is recommended and the authors speculate that the incidence of microscopic polyangiitis may be underestimated because of the under-recognition of systemic involvement in patients with retinal vasculitis.

CONCLUSION

The receipt of a positive ANCA result should always raise the suspicion of a pauci-immune systemic vasculitis and prompt appropriate investigation. The authors emphasise the importance of the evaluation of systemic features in these patients with retinal vasculitis, enabling earlier recognition and thereby preventing significant morbidity and mortality.

Retinal toxicity during pegylated alpha-interferon therapy for chronic hepatitis C: a multifocal electroretinogram investigation

BACKGROUND

Ocular side-effects in the form of retinal ischaemia and haemorrhages have been reported in patients undergoing standard alpha-interferon therapy.

AIM

To assess the ocular impact of therapy with sustained release pegylated alpha-2a interferon (Pegasys) for chronic hepatitis C.

METHODS

Ten patients receiving Pegasys and ribavirin and 10 healthy volunteers were recruited. Patients underwent full ophthalmic investigations and multifocal electroretinogram testing at baseline, at regular intervals during treatment and post-treatment. The multifocal electroretinogram maps retinal function. Responses were compared with sequential recordings from healthy volunteers.

RESULTS

All patients had normal clinical ophthalmic investigations at baseline. During therapy a single patient experienced central visual disturbance lasting 24 h with no prolonged ill effect. No other patient was aware of any change in vision. Fundal abnormalities appeared in five patients during treatment. The multifocal electroretinogram showed reductions in retinal function in five patients. Nine of 10 patients exhibited abnormalities on at least one multifocal electroretinogram or fundoscopic investigation.

CONCLUSIONS

Subclinical retinal toxicity during anti-viral therapy with pegylated alpha-interferon and ribavirin was frequent in this study and it suggests that patients should be warned of this risk and monitored during therapy.

Quantitation of PGE9509924, a novel, nonfluorinated quinolone, in rat plasma using liquid chromatography electrospray-tandem mass spectrometry following solid-phase extraction sample clean-up in a 96-well format

PGE9509924, a novel nonfluorinated quinolone, is a potent antibacterial agent with a broad spectrum of activity. A semi-automated method using 96-well format, solid-phase extraction has been developed for quantitating PGE9509924 in rat plasma. The Waters Oasis HLB extraction plate containing a polymeric packing material was found to give the best overall recoveries. All liquid transfer steps other than aliquoting the plasma are accomplished using a 96-channel pipettor. Reverse-phase HPLC with electrospray/MS/MS detection using selective reaction monitoring is used to quantitate the samples. Stable isotopically labeled PGE9509924 is used as the internal standard. The assay is linear over the range from 0.01 to 10 ug/ml. Excellent precision is obtained within a single run and between multiple runs performed on different days. CVs of <6% were observed. The combination of the semi-automated, 96-well parallel sample processing and the short runtime on the LC/MS/MS results in a high throughput assay with reduced operator interaction.

Linking the Rb and polycomb pathways

Polycomb group (PcG) proteins associate to form complexes that repress Hox genes, thereby imposing the patterning of Hox expression required for development. However, these proteins have a second Hox-independent role in regulating cell proliferation. Our results suggest that association between Rb and PcG proteins forms a repressor complex that blocks entry of cells into mitosis. Also, we provide evidence that Rb colocalizes with nuclear PcG complexes and is important for association of PcG complexes with nuclear targets. The Rb-PcG complex may provide a means to link cell cycle arrest to differentiation events leading to embryonic pattern formation.

Lansoprazole treatment of patients with chronic idiopathic laryngitis: a placebo-controlled trial

OBJECTIVE

Previous uncontrolled studies suggested a therapeutic benefit for treating gastroesophageal reflux disease (GERD) among patients with laryngitis. The present study is the first randomized, placebo-controlled, double-blind study of gastric acid suppression among patients with laryngitis in the United States.

METHODS

Patients diagnosed with idiopathic chronic laryngitis were randomized to receive either lansoprazole 30 mg p.o. b.i.d. or a matching placebo for 3 months. Before randomization, all patients underwent upper endoscopy, dual probe ambulatory 24-h esophageal pH-metry, and laryngoscopy, as well as completing a symptom questionnaire for GERD and laryngitis. The primary outcome of treatment was the complete resolution of laryngeal symptoms.

RESULTS

A total of 22 patients with symptoms and signs of chronic laryngitis were enrolled, 20 of whom completed the study. At baseline, there were no significant differences between the two groups with regards to GERD symptoms, erosive esophagitis, proximal and distal esophageal pH-metry, or laryngeal signs and symptoms. In an intention-to-treat analysis, six patients in the lansoprazole group (50%) and only one patient (10%) in the placebo group achieved a complete symptomatic response, p = 0.04. Apart from receiving lansoprazole, there were no significant differences between responders and nonresponders in any of baseline esophageal or laryngeal signs and symptoms.

CONCLUSIONS

Empirical treatment with lansoprazole is efficacious in relieving symptoms of laryngitis compared to placebo. Such treatment can be considered as a first-line option in managing patients with idiopathic chronic laryngitis.

Exit from G1 and S phase of the cell cycle is regulated by repressor complexes containing HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF

We present evidence that Rb forms a repressor containing histone deacetylase (HDAC) and the hSWI/SNF nucleosome remodeling complex, which inhibits transcription of genes for cyclins E and A and arrests cells in the G1 phase of the cell cycle. Phosphorylation of Rb by cyclin D/cdk4 disrupts association with HDAC, relieving repression of the cyclin E gene and G1 arrest. However, the Rb-hSWI/SNF complex persists and is sufficient to maintain repression of the cyclin A and cdc2 genes, inhibiting exit from S phase. HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF then appear to maintain the order of cyclin E and A expression during the cell cycle, which in turn regulates exit from G1 and from S phase, respectively.

Shared governance: time to consider the cons as well as the pros

AIMS

This paper aims to provide a critical appraisal of an approach to the management and organization of nursing work known as shared governance (SG).

BACKGROUND

This approach has its origins in the USA, where, during the past 20 years it has become increasingly influential. The advocates of SG claim that it can, inter alia, improve recruitment and retention rates, boost morale, and help raise clinical skills. Little wonder that SG in now beginning to make significant inroads into the NHS. ORIGIN OF INFORMATION: However, a trawl through the extensive US literature, using printed and online (e.g. BIDS, CINHAL, MEDLINE, etc.) bibliographical sources, suggests that the claimed benefits of SG should be treated with caution.

KEY ISSUES

Much of the existing published research appears to be both methodologically flawed and lacking in any critical edge. While many researchers and commentators appear only too willing to highlight what they see as the promise of SG, they shy away from exploring any potential pitfalls. One consequence of this is that many of the putative benefits SG is said to confer, may in fact be more apparent than real.

CONCLUSIONS

Nurses and nurse managers need to be apprised of and consider seriously, the possible cons as well as the potential pros of SG, if any promise it may have is to be realized.

Minor histocompatibility antigens as targets for T-cell therapy after bone marrow transplantation

In allogeneic bone marrow transplantation, differences between donor and recipient at minor histocompatibility loci, which encode allelic proteins containing variant peptide sequences, may result in adverse immune reactions such as graft-versus-host disease (GVHD), or graft rejection, but also a beneficial graft versus leukemia (GVL) response. Some minor H antigens are restricted in their expression to hematopoietic cells, including leukemic progenitors, suggesting it may be possible to separate GVHD and GVL responses. The antigenic peptides for a few human minor H antigens have been identified, and efforts to identify the genes encoding minor H antigens are being pursued. These advances promise to provide a more detailed understanding of the immunobiology and pathogenesis of GVHD and GVL responses and opportunities to selectively augment T-cell responses that promote a GVL effect by adoptive immunotherapy with T-cell clones specific for defined minor H determinants.

Functional characterization of ETV6 and ETV6/CBFA2 in the regulation of the MCSFR proximal promoter

The ETV6/CBFA2 (TEL/AML1) fusion gene occurs as a result of the chromosome translocation t(12;21)(p13;q22) in up to 30% of children diagnosed with B cell precursor (cd10+, cd19+) acute lymphoblastic leukemia. Leukemic cells that have acquired the t(12;21) usually demonstrate loss of the remaining normal ETV6 (TEL) allele. Using reporter gene assays we have functionally characterized both the normal ETV6 and ETV6/CBFA2 fusion proteins in the regulation of the MCSFR proximal promoter. Neither ETV6 or ETV6/CBFA2 has any significant, detectable effect on the promoter by itself. However, both ETV6 and ETV6/CBFA2 inhibit the activation of the promoter by CBFA2B(AML1B) and C/EBPa. We have shown that a 29-bp region of the MCSFR promoter containing the binding sites for CBFA2B and C/EBPa is sufficient for the inhibition by ETV6 and ETV6/CBFA2. Mutational analysis of the MCSFR promoter revealed that binding of both CBFA2B and C/EBPa to their respective sites is necessary for the inhibition by ETV6 and ETV6/CBFA2. Deletion of the helix-loop-helix (HLH) region from the cDNAs of ETV6 and ETV6/CBFA2 decreased but did not completely abrogate the ability of either construct to inhibit promoter activation. We also found that the ETS DNA binding region of ETV6 is necessary for inhibition of the promoter. Addition of ETS1 and FLI1, two ETS family members that have homology in the 5' HLH region, but not Spi1, an ETS family member without the 5' HLH region, also inhibited reporter gene expression. Our data show that the inhibition mediated by ETV6 and ETV6/CBFA2, in the context of the MCSFR promoter, depend on interactions with other proteins, not just CBFA2B. Our results also indicate that the transactivation characteristics of ETV6/CBFA2 are a combination of positive and negative regulatory properties.

A receptor tyrosine kinase cDNA isolated from a population of enriched primitive hematopoietic cells and exhibiting close genetic linkage to c-kit

We have cloned a receptor tyrosine kinase cDNA, designated fetal liver kinase 1 (Flk-1), from mouse cell populations enriched for hematopoietic stem and progenitor cells. Sequence analysis of this clone reveals strong homology to the c-Kit subfamily of receptor kinases, and in particular to the Flt gene product. Chromosomal mapping shows that the Flk-1, Kit, and Pdgfra genes are closely linked. Flk-1 mRNA is expressed in primitive and more mature hematopoietic cells as well as in a wide variety of nonhematopoietic tissues.

Extracranial and digital vascular events: an analysis of methods in BVP amplitude and biofeedback research

The purpose of the present study was to assess and compare the effects of within and between-session exposure to environmental context on left temporal artery pulse amplitude, right temporal artery pulse amplitude, and left digital pulse amplitude. Subjects were individually tested for 20 min daily over a period of eight consecutive days. A significant interaction was found for Position X Interval. These results show that exposure to the experimental context occurs with diametrically opposite effects on temporalis and digital pulse amplitude within session. Moreover, these results would support the hypothesis that controversial findings within the headache and biofeedback literature may be partially attributable to methodological differences where, for example, different authors use different transducer locations and/or evaluate pulse amplitude at different points within or among sessions. Indeed, research on the effects or lack thereof of therapeutic manipulations may have little or nothing to do with the intervention or experimental manipulations themselves. These effects may be masked or augmented by subject and methodological confounds during baseline and testing conditions.

A community-centered alcoholism assessment/treatment service: a descriptive study

This paper describes socio-demographic, alcohol-related, legal, medical, behavioural and treatment characteristics of 407 patients with problems of alcoholism/drug abuse assessed over a period of three years in a community oriented assessment and treatment program. The results show that patients entering this program represent a cross section of alcoholics in the area. These patients are similar to those entering traditional outpatient and residential facilities on most demographic variables; severity of alcoholism, length of history, and previous treatment experience. However, they are slightly younger and differ significantly from the others on their sources of referral. Over the three year period a significant change has occurred in the relationship between the program and the sources of referral. The implications of these findings for planning comprehensive treatment services for alcoholism are discussed.

Modification of the macaque's vestibulo-ocular reflex by picrotoxin

The vestibulo-ocular reflex (VOR) in the macaque was tested by a modified Bárány spinning test before and after subcutaneous administration of 1 mg/kg of picrotoxin. The drug caused a decrease in the nystagmus time constant to a value near that of the cupula and a decrease in mystagmus asymmetry. Picrotoxin prevented diazepam from increasing the time constant of vestibular nystagmus. Furthermore, picrotoxin reduced the nystagmus time constant after vermisectomy, a lesion that increases the nystagmus time constant and prevents some VOR modifications. Because picrotoxin and diazepam interact antagonistically in the gamma-aminobutyric acid (GABA) neurotransmitter system, these results show a role of GABA in the neural network that transforms a short cupula time constant into a longer nystagmus time constant.

Active mirror: a large-aperture medium-repetition rate Nd:glass amplifier

Progress in the development of Nd:glass active mirror laser amplifiers is presented. Included is a detailed discussion of hardware design as well as gain and repetition rate performance. Finally, multiunit test results, in a higher power and high energy beam, are presented.

Pre-participation sports assessment--an objective evaluation

The yield from a pre-participation sports examination consisting of a review of the medical history, routine physical examination, musculoskeletal examination, laboratory screening and an assessment of fitness by evaluation of body composition, flexibility, and muscular strength testing was studied. There were 701 students evaluated. Two students (0.3%) were excluded from participation because of medical problems and seven (1%) because of orthopedic problems. Sixty students (8.6%) were referred for additional medical evaluation. Thirty-five students (5.0%) required further orthopedic evaluation. All of the students who required additional evaluations were eventually granted permission to participate. The review of the medical history was positive in seven of the restricted students and 40 of the referred students. The routine physical examination was normal in the two restricted students and abnormal in 14 of the referred students. The musculoskeletal examination was abnormal in all of the students restricted or referred for orthopedic problems. The assessment of physical fitness revealed that 32% of the students had excessive body fat, 10% to 15% of both boys and girls had excessive muscle tightness in either the upper or lower body and approximately 5% of the students had weakness in hip abductors or flexors. Significant unilateral strength deficits were also found. When performed for the purpose of restricting participation or referring students for additional evaluation, the medical history and musculoskeletal examination are the components of the pre-participation sports examination with the highest yield. Additionally, the aspects of the examination which related to fitness revealed a significant number of abnormalities.

Modifications of vestibulo-ocular reflex induced by diazepam: experiments in the macaque

The vestibulo-ocular reflex in the macaque was tested before and after intravenous administration of diazepam. The drug effect was marked by decrease in gain and increase in time constant of nystagmus in response to a modified Bárány test and by reduction in directional asymmetry of nystagmus. Because the time course of reduction in gain differed from the time course of increase in time constant, diazepam probably has more than one site of action. These results emphasize the complexity of neural processing in the vestibulo-ocular reflex arc.

Response of the vestibulo-ocular reflex to differing programs of acceleration

The vestibulo-ocular reflex of normal monkeys was tested by a modified Bárány spinning test (B-test) and by sinosoidal rotation. The two tests gave concordant estimates of the time constant and corner frequency. Deviation from concordance was caused largely by modification of the reflex during the testing procedures. As a means of estimating both time constant and corner frequency in the vestibulo-ocular reflex, the B-test is to be preferred to sinusoidal rotation because although both tests provide similar information, the B-test is the more rapidly performed and analyzed and the B-test modifies the reflex less.

Modification of the macaque's vestibulo-ocular reflex after ablation of the cerebellar vermis

In macaque, the vestibulo-ocular reflex (VOR) as evaluated by the time constant of nystagmus in a modified Bárány spinning test, shows a regular pattern of change with time after ablation of the vermis cerebelli. One day ablation the time constant is in the low normal range; it then increases, and after one week assumes values in the high normal range. While the time constant is high, the VOR is resistant to modification by repeated testing, but may be modified by unidirectional optokinetic nystagmus and by experience with reversing spectacles. These results suggest that the vermis of the cerebellum plays no crucial role in modifications of the VOR by visual inputs, but is involved when the VOR is modified by repeated vestibular experience.

The nature of "spots" on soft lenses

Of 278 consecutive therapeutic soft lens wearers, 19 (6.8%) developed discrete lens opacities on the anterior (air) surface of the lens. The incidence rose to 16.6% in patients fitted for dry eye syndromes, to 19% in bullous keratopathy and to 20% in exposure keratitis and trichiasis, if worn for longer than 2 weeks. These opacities were not associated with medications. Scanning electron microscopy demonstrated cracks on the anterior lens surface associated with these opacities. Transmission electron microscopy demonstrated the opacities to be amorphous material with extensions of the contact lens polymer into the substance of these opacities. Lipid, as demonstrated by histochemical methods, was found in these opacities. It is likely that the combination of dryness, stress on the lens surface, and lipid deposition act to alter the structure of the plastic and cause these opacities.