Protein interaction networks in the vasculature prioritize genes and pathways underlying coronary artery disease

Population-based association studies have identified many genetic risk loci for coronary artery disease (CAD), but it is often unclear how genes within these loci are linked to CAD. Here, we perform interaction proteomics for 11 CAD-risk genes to map their protein-protein interactions (PPIs) in human vascular cells and elucidate their roles in CAD. The resulting PPI networks contain interactions that are outside of known biology in the vasculature and are enriched for genes involved in immunity-related and arterial-wall-specific mechanisms. Several PPI networks derived from smooth muscle cells are significantly enriched for genetic variants associated with CAD and related vascular phenotypes. Furthermore, the networks identify 61 genes that are found in genetic loci associated with risk of CAD, prioritizing them as the causal candidates within these loci. These findings indicate that the PPI networks we have generated are a rich resource for guiding future research into the molecular pathogenesis of CAD.

Constitutively active autophagy in macrophages dampens inflammation through metabolic and post-transcriptional regulation of cytokine production

Autophagy is an essential cellular process that is deeply integrated with innate immune signaling; however, studies that examine the impact of autophagic modulation in the context of inflammatory conditions are lacking. Here, using mice with a constitutively active variant of the autophagy gene Beclin1, we show that increased autophagy dampens cytokine production during a model of macrophage activation syndrome and in adherent-invasive Escherichia coli (AIEC) infection. Moreover, loss of functional autophagy through conditional deletion of Beclin1 in myeloid cells significantly enhances innate immunity in these contexts. We further analyzed primary macrophages from these animals with a combination of transcriptomics and proteomics to identify mechanistic targets downstream of autophagy. Our study reveals glutamine/glutathione metabolism and the RNF128/TBK1 axis as independent regulators of inflammation. Altogether, our work highlights increased autophagic flux as a potential approach to reduce inflammation and defines independent mechanistic cascades involved in this control.

Genetic Tools for Studying the Roles of Sphingolipids in Viral Infections

Sphingolipids are a critical family of membrane lipids with diverse functions in eukaryotic cells, and a growing body of literature supports that these lipids play essential roles during the lifecycles of viruses. While small molecule inhibitors of sphingolipid synthesis and metabolism are widely used, the advent of CRISPR-based genomic editing techniques allows for nuanced exploration into the manners in which sphingolipids influence various stages of viral infections. Here we describe some of these critical considerations needed in designing studies utilizing genomic editing techniques for manipulating the sphingolipid metabolic pathway, as well as the current body of literature regarding how viruses depend on the products of this pathway. Here, we highlight the ways in which sphingolipids affect viruses as these pathogens interact with and influence their host cell and describe some of the many open questions remaining in the field.

Omicron neutralizing antibody response following booster vaccination compared with breakthrough infection

BACKGROUND

The spread of the vaccine-resistant Omicron severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants threatens unvaccinated and fully vaccinated individuals, and accelerated booster vaccination campaigns are underway to mitigate the ongoing wave of Omicron cases. The immunity provided by standard vaccine regimens, boosted regimens, and immune responses elicited by vaccination plus natural infection remain incompletely understood. The magnitude, quality, and durability of serological responses, and the likelihood of protection against future SARS-CoV-2 variants following these modes of exposure, are poorly characterized but are critical to the future trajectory of the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

Ninety-nine individuals were semi-randomly selected from a larger vaccination cohort following vaccination and, in some cases, breakthrough infection. We analyzed spike receptor-binding domain-specific immunoglobulin G (IgG), IgA, and IgM by enzyme-linked immunosorbent assay, neutralizing antibody titers against live SARS-CoV-2 variants, and antibody-dependent cell-mediated phagocytosis.

FINDINGS

In 99 vaccinated adults, compared with responses after two doses of an mRNA regimen, the immune responses 3 months after a third vaccine dose and 1 month after breakthrough infection due to prior variants show dramatic increases in magnitude, potency, and breadth, including increased antibody-dependent cellular phagocytosis and robust neutralization of the currently circulating Omicron BA.2 variant.

CONCLUSIONS

Boosters and natural infection substantially boost immune responses. As the number of Omicron sub-variant cases rise and as global vaccination and booster campaigns continue, an increasing proportion of the world's population will acquire potent immune responses that may be protective against future SARS-CoV-2 variants.

FUNDING

This work was funded by the M. J. Murdock Charitable Trust, the OHSU Foundation, the NIH (T32HL083808), and OHSU Innovative IDEA.

Omicron neutralizing antibody response following booster vaccination compared with breakthrough infection

The rapid spread of the vaccine-resistant Omicron variant of SARS-CoV-2 presents a renewed threat to both unvaccinated and fully vaccinated individuals, and accelerated booster vaccination campaigns are underway to mitigate the ongoing wave of Omicron cases. The degree of immunity provided by standard vaccine regimens, boosted regimens, and immune responses elicited by the combination of vaccination and natural infection remain incompletely understood. The relative magnitude, quality and durability of serological responses, and the likelihood of neutralizing protection against future SARS-CoV-2 variants following these modes of exposure are unknown but are critical to the future trajectory of the COVID-19 pandemic. In this study of 99 vaccinated adults, we find that compared with responses after two doses of an mRNA regimen, the immune responses three months after a third vaccine dose and one month after breakthrough infection due to prior variants show dramatic increases in magnitude, potency, and breadth, including increased antibody dependent cellular phagocytosis and robust neutralization of the recently circulating Omicron variant. These results suggest that as the number of Omicron cases rise and as global vaccination and booster campaigns continue, an increasing proportion of the world’s population will acquire potent immune responses that may be protective against future SARS-CoV-2 variants.

Vaccination before or after SARS-CoV-2 infection leads to robust humoral response and antibodies that effectively neutralize variants

Current coronavirus disease 2019 (COVID-19) vaccines effectively reduce overall morbidity and mortality and are vitally important to controlling the pandemic. Individuals who previously recovered from COVID-19 have enhanced immune responses after vaccination (hybrid immunity) compared with their naïve-vaccinated peers; however, the effects of post-vaccination breakthrough infections on humoral immune response remain to be determined. Here, we measure neutralizing antibody responses from 104 vaccinated individuals, including those with breakthrough infections, hybrid immunity, and no infection history. We find that human immune sera after breakthrough infection and vaccination after natural infection broadly neutralize SARS-CoV-2 (severe acute respiratory coronavirus 2) variants to a similar degree. Although age negatively correlates with antibody response after vaccination alone, no correlation with age was found in breakthrough or hybrid immune groups. Together, our data suggest that the additional antigen exposure from natural infection substantially boosts the quantity, quality, and breadth of humoral immune response regardless of whether it occurs before or after vaccination.

Pyoderma Gangrenosum as the Initial Presentation of Inflammatory Bowel Disease

Introduction/Objective

Pyoderma gangrenosum is a neutrophilic dermatosis, commonly associated with arthritis, psoriasis, and systemic lupus erythematosus. It is also an aggressive manifestation of extra-intestinal inflammatory bowel disease affecting less than 5% of patients with ulcerative colitis and Crohn disease. We present a case of pyoderma gangrenosum as an initial and rapidly progressive manifestation of Crohn disease.

Methods

A 35-year-old man presented with fecal urgency, periumbilical pain, and frequent diarrhea, with stool cultures revealing no infectious etiology. Colonoscopy demonstrated active inflammatory bowel disease consistent with Crohn disease. Concurrently, patient developed an ulcer on right lower extremity not otherwise contributed to history of trauma or injury. Biopsy of right lower extremity ulcer revealed histopathologic findings consistent with pyoderma gangrenosum. Despite medical management, and prolonged use of wound care and wound vac, patient’s non-healing ulcer continued to geographically expand, resulting in ankle contracture. A right below the knee amputation was performed and amputation specimen was sent to pathology for further diagnostic evaluation.

Results

Gross examination revealed an extensive cutaneous ulcer measuring 22.1cm x 11.7cm x 0.3cm and involving the anterior medial aspect of the right lower extremity with medial and posterior extension down to the dorsum of the foot with broad deep tissue destruction and exposure of fascia and tendon. Microscopic examination revealed severe ulceration, suppurative necrosis, superficial and deep vasculitis confined to the ulcer bed.

Surrounding soft tissue revealed chronic myopathic changes secondary to ischemia. Foci of commensal filamentous gram-positive bacterial colonization in a nidus of necrosis were also identified. The inflammatory pattern involved predominantly neutrophils with weak recruitment of other inflammatory cells, consistent with pyoderma gangrenosum.

Conclusion

This case highlights the debilitating extent of Crohn disease, its detrimental effects on the patient’s quality of life, and the diagnostic and treatment challenges it poses to clinicians in managing Crohn disease and its complications.

MRI estimated changes in visceral adipose tissue and liver fat fraction in patients with obesity during a very low-calorie-ketogenic diet compared to a standard low-calorie diet

AIM

To compare the changes in visceral adipose tissue (VAT), liver fat fraction, and liver stiffness using quantitative magnetic resonance imaging (MRI) during a very-low-calorie ketogenic (VLCK) diet and a standard low-calorie diet (LC).

MATERIALS AND METHODS

The study involved secondary analysis of prospective collected clinical data. Patients undergoing weight loss interventions were randomised to either a LC or a VLCK diet. VAT, liver fat fraction, and stiffness were measured at baseline and after 2 months.

RESULTS

Forty-six patients were included; 39 patients were evaluated at baseline and at 2 months follow-up. Mean weight loss was -9.7±3.8 kg (interquartile range [IQR]: -12.3; -7 kg) in the VLCK group and -1.67±2.2 kg (IQR: -3.3, -0.1 kg) in the LC group (p<0.0001). Mean VAT reductions were -39.3±40 cm² (IQR: -52, -10 cm²) and -12.5±38.3 cm² (IQR: -29, 5 cm²; p=0.0398), and mean liver proton density fat fraction (PDFF) reductions were -4.77±4.2% (IQR: -7.3, -1.7%) and -0.79±1.7%, (IQR: -1.8, -0.4%; p<0.005) in the VLCK group and in the LC group, respectively. No significant changes in liver stiffness occurred from baseline to follow-up.

CONCLUSION

A VLCK diet resulted in greater weight loss than a standard low-calorie diet and in significantly greater reduction in liver PDFF. As anthropometric measurements may not correlate with liver fat changes, it may be advantageous to include quantitative MRI to the monitoring strategies of patients undergoing weight-loss programmes.

The Squeaky Yeast Gets Greased: The Roles of Host Lipids in the Clearance of Pathogenic Fungi

Fungal infections remain a global health threat with high morbidity and mortality. The human immune system must, therefore, perpetually defend against invasive fungal infections. Phagocytosis is critical for the clearance of fungal pathogens, as this cellular process allows select immune cells to internalize and destroy invading fungal cells. While much is known about the protein players that enable phagocytosis, the various roles that lipids play during this fundamental innate immune process are still being illuminated. In this review, we describe recent discoveries that shed new light on the mechanisms by which host lipids enable the phagocytic uptake and clearance of fungal pathogens.

P754 Severe aortic stenosis with preserved ejection prognostic differences according to flow status and gradient fraction: a Spanish multicentre study

Background and objectives

Low-flow low-gradient (LFLG) aortic stenosis portends bad prognosis in different series. The objective of this study was to evaluate the evolution of this entity in our country.

Methods

We included 1394 consecutive patients evaluated between 2008-2016 with severe AS (AVA &lt;1 cm²) and ejection fraction&gt; 50% from 14 Spanish centres. The results (aortic valve intervention and mortality) were compared using the Kaplan-Meier survival analysis.

Results

Three groups based on gradient and flow status were established (high gradient: HG, normal flow under gradient: NFLG, low gradient low flow: LFLG). No significant demographic or clinical differences between groups were observed. After a follow-up of 61.52 months (IQR 43.5-86.5), 551 (73.8%) HG, 268 (35.4%) with NFLG and 81 (57.9%) LFLG received intervention, with a later surgery/TAVI indication in the LFLG group compared with HG group (p = 0.001) (Figure 1). The analysis of the Kaplan-Meier mortality curves showed no significant differences.

Conclusions

Patients with LFLG aortic stenosis with normal ejection fraction received less and later aortic valve intervention than the HG group with no significant differences in mortality.

Abstract P754 Figure. Time to surgery

Visualization and Quantification of Phagocytosis by Neutrophils

Phagocytosis by phagocytes such as neutrophils is a crucial part of the host innate immune response against invading pathogens. Phagocytosis is a complex process that initiates with the binding of the particles on the cell surface of the phagocytes through the interaction of pattern recognition receptors with ligands on the surface of the pathogens. During this process, phagocytes undergo extensive membrane reorganization and cytoskeleton rearrangement at their cell surface. To gain better insight about the molecular mechanisms of this dynamic cellular process, visualization and quantification in a high-throughput manner is essential. Here, we describe a microscope-based method to visualize and quantify phagocytic uptake of pathogens (such as bacteria and fungi) and model particulates that are larger than 0.5 μm (such as Zymosan A and IgG-coated beads).

C1orf106 is a colitis risk gene that regulates stability of epithelial adherens junctions

Polymorphisms in C1orf106 are associated with increased risk of inflammatory bowel disease (IBD). However, the function of C1orf106 and the consequences of disease-associated polymorphisms are unknown. Here we demonstrate that C1orf106 regulates adherens junction stability by regulating the degradation of cytohesin-1, a guanine nucleotide exchange factor that controls activation of ARF6. By limiting cytohesin-1-dependent ARF6 activation, C1orf106 stabilizes adherens junctions. Consistent with this model, C1orf106^-/- mice exhibit defects in the intestinal epithelial cell barrier, a phenotype observed in IBD patients that confers increased susceptibility to intestinal pathogens. Furthermore, the IBD risk variant increases C1orf106 ubiquitination and turnover with consequent functional impairments. These findings delineate a mechanism by which a genetic polymorphism fine-tunes intestinal epithelial barrier integrity and elucidate a fundamental mechanism of cellular junctional control.

TMEM258 Is a Component of the Oligosaccharyltransferase Complex Controlling ER Stress and Intestinal Inflammation

Significant insights into disease pathogenesis have been gleaned from population-level genetic studies; however, many loci associated with complex genetic disease contain numerous genes, and phenotypic associations cannot be assigned unequivocally. In particular, a gene-dense locus on chromosome 11 (61.5-61.65 Mb) has been associated with inflammatory bowel disease, rheumatoid arthritis, and coronary artery disease. Here, we identify TMEM258 within this locus as a central regulator of intestinal inflammation. Strikingly, Tmem258 haploinsufficient mice exhibit severe intestinal inflammation in a model of colitis. At the mechanistic level, we demonstrate that TMEM258 is a required component of the oligosaccharyltransferase complex and is essential for N-linked protein glycosylation. Consequently, homozygous deficiency of Tmem258 in colonic organoids results in unresolved endoplasmic reticulum (ER) stress culminating in apoptosis. Collectively, our results demonstrate that TMEM258 is a central mediator of ER quality control and intestinal homeostasis.

Type 2 Diabetes Variants Disrupt Function of SLC16A11 through Two Distinct Mechanisms

Type 2 diabetes (T2D) affects Latinos at twice the rate seen in populations of European descent. We recently identified a risk haplotype spanning SLC16A11 that explains ∼20% of the increased T2D prevalence in Mexico. Here, through genetic fine-mapping, we define a set of tightly linked variants likely to contain the causal allele(s). We show that variants on the T2D-associated haplotype have two distinct effects: (1) decreasing SLC16A11 expression in liver and (2) disrupting a key interaction with basigin, thereby reducing cell-surface localization. Both independent mechanisms reduce SLC16A11 function and suggest SLC16A11 is the causal gene at this locus. To gain insight into how SLC16A11 disruption impacts T2D risk, we demonstrate that SLC16A11 is a proton-coupled monocarboxylate transporter and that genetic perturbation of SLC16A11 induces changes in fatty acid and lipid metabolism that are associated with increased T2D risk. Our findings suggest that increasing SLC16A11 function could be therapeutically beneficial for T2D. VIDEO ABSTRACT.

Proteomic mapping of cytosol-facing outer mitochondrial and ER membranes in living human cells by proximity biotinylation

The cytosol-facing membranes of cellular organelles contain proteins that enable signal transduction, regulation of morphology and trafficking, protein import and export, and other specialized processes. Discovery of these proteins by traditional biochemical fractionation can be plagued with contaminants and loss of key components. Using peroxidase-mediated proximity biotinylation, we captured and identified endogenous proteins on the outer mitochondrial membrane (OMM) and endoplasmic reticulum membrane (ERM) of living human fibroblasts. The proteomes of 137 and 634 proteins, respectively, are highly specific and highlight 94 potentially novel mitochondrial or ER proteins. Dataset intersection identified protein candidates potentially localized to mitochondria-ER contact sites. We found that one candidate, the tail-anchored, PDZ-domain-containing OMM protein SYNJ2BP, dramatically increases mitochondrial contacts with rough ER when overexpressed. Immunoprecipitation-mass spectrometry identified ribosome-binding protein 1 (RRBP1) as SYNJ2BP's ERM binding partner. Our results highlight the power of proximity biotinylation to yield insights into the molecular composition and function of intracellular membranes.

Analysis of Applied Behavior Treatment for Children with Autism Spectrum Disorder

According to Boesch et al., people with autism spectrum disorder (ASD) are at a greater risk of developing harmful behaviors, such as self-aggression and other challenging behaviors than individuals with normal development do not exhibit. The method of approach that is supported by scientific evidence for interventional procedures is applied behavior analysis, reported by Carr et al. [1].

Aim

In order to provide evidence-based intervention for autism from this approach in practice.

Method

In reference to a longitudinal approach, an intervention program was designed and implemented to serve 40 children with ASD, who were treated for one (1) year at the Victory BRT Institute in Florida, US. The behaviors targeted for reduction (excess behavioral), are the following: physical aggression, self-aggression and non-compliance. The program began with a baseline (12 consecutive days) with observations at home and others different natural contexts. The last three (3) months of the year consisted of monthly follow-up sessions to monitor the treatment implemented. The results were analyzed by repeated measures, ANOVA Sig (P = 0.003) (F = 8). Analyses show that the critical level associated with the effect of time-content interaction is strong, so the treatment generated a positive effect by reducing the behaviors targeted in time.

Conclusions

These results provide evidence that interventions from applied behavior analysis are effective.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Fast mold surface temperature evolution: relevance of asymmetric surface heating for morphology of iPP molded samples

It is widely accepted that mold temperature has a strong effect on the amount of molecular orientation and morphology developed in a non-isothermal flowing melt.

Arylsulfatase B (N-acetylgalactosamine-4-sulfatase): potential role as a biomarker in prostate cancer

BACKGROUND

The enzyme Arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase) degrades chondroitin-4-sulfate (C4S) and is reduced in malignant colonic and mammary tissues, but has not previously been evaluated in prostate cancer.

METHODS

ARSB immunostaining was performed on two tissue microarrays (TMA) and analyzed by digital image analysis, generating ARSB H-scores for prevalence and intensity of epithelial, stromal, and combined epithelial and stromal immunostaining. Also, paired malignant and normal prostate tissues were analyzed for ARSB activity, C4S, total sulfated glycosaminoglycans, and versican content. The quantities of C4S and of the epidermal growth factor receptor that co-immunoprecipitated with versican were determined in the normal and malignant paired prostate tissues.

RESULTS

44 cases of prostate cancer were paired by age (± 5y), race, Gleason score (in order), and pathologic TNM score. The pairs differed by recurrence vs. non-recurrence of elevated PSA at 4 or more years. When TMA cores were analyzed for ARSB H-score, 18 of the 22 pairs had lower ARSB H-scores in the recurrent member of the pair, whereas higher initial PSA values were associated with recurrence in only 65% of the paired cases. In a second TMA, Gleason scores 6 and 7 were associated with higher ARSB H-scores than Gleason scores 8 and 9 for stroma, epithelium, and stroma and epithelium combined (p=0.052, p=0.015, p<0.0001, respectively) and were inversely correlated (r = −0.98, −0.97, and −0.99, respectively). In other paired normal and malignant prostate tissues, ARSB activity was significantly higher in the normal tissues, and C4S and versican values were lower (p<0.0001). C4S that co-immunoprecipitated with versican was greater in the malignant than in the normal tissue, whereas total EGFR that co-immunoprecipitated with versican was reduced.

DISCUSSION

Study findings suggest that ARSB may be useful as a prognostic biomarker in prostate cancer, and that the biological action of ARSB on chondroitin sulfate may impact upon versican’s effects in the tumor microenvironment.

Campomelic dysplasia: case report and review

Initial ultrasound of a fetus in the third trimester demonstrated shortened and bent fetal extremities with a narrow and misshapen thorax. These findings were suggestive of a fetus affected with a possible lethal skeletal dysplasia. Decisions regarding antepartum, intrapartum and neonatal care were made in this context. A newborn with campomelic dysplasia was delivered and suffered a rapid downhill course.

E22K mutation of RLC that causes familial hypertrophic cardiomyopathy in heterozygous mouse myocardium: effect on cross-bridge kinetics

Familial hypertrophic cardiomyopathy is a disease characterized by left ventricular and/or septal hypertrophy and myofibrillar disarray. It is caused by mutations in sarcomeric proteins, including the ventricular isoform of myosin regulatory light chain (RLC). The E22K mutation is located in the RLC Ca(2+)-binding site. We have studied transgenic (Tg) mouse cardiac myofibrils during single-turnover contraction to examine the influence of E22K mutation on 1) dissociation time (tau(1)) of myosin heads from thin filaments, 2) rebinding time (tau(2)) of the cross bridges to actin, and 3) dissociation time (tau(3)) of ADP from the active site of myosin. tau(1) was determined from the increase in the rate of rotation of actin monomer to which a cross bridge was bound. tau(2) was determined from the rate of anisotropy change of the recombinant essential light chain of myosin labeled with rhodamine exchanged for native light chain (LC1) in the cardiac myofibrils. tau(3) was determined from anisotropy of muscle preloaded with a stoichiometric amount of fluorescent ADP. Cross bridges were induced to undergo a single detachment-attachment cycle by a precise delivery of stoichiometric ATP from a caged precursor. The times were measured in Tg-mutated (Tg-m) heart myofibrils overexpressing the E22K mutation of human cardiac RLC. Tg wild-type (Tg-wt) and non-Tg muscles acted as controls. tau(1) was statistically greater in Tg-m than in controls. tau(2) was shorter in Tg-m than in non-Tg, but the same as in Tg-wt. tau(3) was the same in Tg-m and controls. To determine whether the difference in tau(1) was due to intrinsic difference in myosin, we estimated binding of Tg-m and Tg-wt myosin to fluorescently labeled actin by measuring fluorescent lifetime and time-resolved anisotropy. No difference in binding was observed. These results suggest that the E22K mutation has no effect on mechanical properties of cross bridges. The slight increase in tau(1) was probably caused by myofibrillar disarray. The decrease in tau(2) of Tg hearts was probably caused by replacement of the mouse RLC for the human isoform in the Tg mice.

Expression of entry receptor nectin-1 of herpes simplex virus 1 and/or herpes simplex virus 2 in normal and neoplastic human nervous system tissues

Herpes simplex virus 1 and/or Herpes simplex virus 2 (HSV) are important pathogens of human nervous system (NS) and genetically modified HSV strains have been proposed as vectors for gene therapy targeting the brain and brain tumors. Nectin-1 is an immunoglobulin-like adhesion molecule that participates in the formation of synapses and serves as an entry receptor for HSV. The expression pattern of nectin-1 in normal human NS and brain tumors is not well understood. To better understand the nectin-1 expression in normal and neoplastic human NS, immunohistochemistry was used to detect the nectin-1 expression in sections of normal human brain, spinal cord and trigeminal and dorsal root ganglia (n=10) and in sections of primary NS neoplasms (n=22). In normal human NS, nectin-1 was detected in the soma and processes of central and peripheral neurons, in ependymal cells, choroid plexus epithelial cells, vascular endothelial cells and meningothelial cells. Oligodendrocytes, astrocytes, vascular smooth muscle cells, and Schwann cells showed variable immunoreactivity. Among tumors, schwannoma, fibrous meningioma, and medulloblastoma were nectin-1 negative. Oligodendroglioma, ependymoma, pilocytic astrocytoma, pleomorphic xanthoastrocytoma, diffuse astrocytoma, anaplastic astrocytoma, glioblastoma multiforme and meningothelial meningioma showed weak focal nectin-1-positivity. Ganglion cells of ganglioglioma were strongly positive. These studies provide novel information about the expression of nectin-1 in normal and neoplastic NS, and thus may lead to a better understanding of cell targeting by HSV during HSV-induced neurological disease and during a HSV-based gene therapy.

Familial hypertrophic cardiomyopathy mutations in the regulatory light chains of myosin affect their structure, Ca2+ binding, and phosphorylation

The effect of the familial hypertrophic cardiomyopathy mutations, A13T, F18L, E22K, R58Q, and P95A, found in the regulatory light chains of human cardiac myosin has been investigated. The results demonstrate that E22K and R58Q, located in the immediate extension of the helices flanking the regulatory light chain Ca(2+) binding site, had dramatically altered Ca(2+) binding properties. The K(Ca) value for E22K was decreased by approximately 17-fold compared with the wild-type light chain, and the R58Q mutant did not bind Ca(2+). Interestingly, Ca(2+) binding to the R58Q mutant was restored upon phosphorylation, whereas the E22K mutant could not be phosphorylated. In addition, the alpha-helical content of phosphorylated R58Q greatly increased with Ca(2+) binding. The A13T mutation, located near the phosphorylation site (Ser-15) of the human cardiac regulatory light chain, had 3-fold lower K(Ca) than wild-type light chain, whereas phosphorylation of this mutant increased the Ca(2+) affinity 6-fold. Whereas phosphorylation of wild-type light chain decreased its Ca(2+) affinity, the opposite was true for A13T. The alpha-helical content of the A13T mutant returned to the level of wild-type light chain upon phosphorylation. The phosphorylation and Ca(2+) binding properties of the regulatory light chain of human cardiac myosin are important for physiological function, and alteration any of these could contribute to the development of hypertrophic cardiomyopathy.

Costs of managing Helicobacter pylori-infected ulcer patients after initial therapy

BACKGROUND

The objective of this research was to evaluate the outcomes and costs of alternative approaches to managing patients previously treated for peptic ulcer disease and Helicobacter pylori infection.

MATERIALS AND METHODS

A decision-analytic model was used to compare (1a) urease breath testing (UBT) for assessment of H. pylori status versus (1b) observation without further testing or treatment, among patients who were symptom-free following initial antimicrobial and antisecretory therapy for endoscopically demonstrated ulcer and H. pylori infection; and (2a) UBT versus (2b) repeat endoscopy with H. pylori testing, and versus (2c) repeat antimicrobial and antisecretory therapy without further testing, among patients who remained symptomatic following initial therapy.

RESULTS

Among patients who were symptom free after initial therapy, 6.1% receiving UBT had symptomatic ulcer at one year, compared to 18.2% of those simply observed. The expected first-year cost per symptom-free patient following initial therapy was $591 for UBT compared to $480 for observation. Among patients with persistent symptoms after initial therapy, 21% receiving repeat therapy had symptomatic ulcer at one year, compared to 23.8% receiving repeat endoscopy, and 23.3% receiving UBT. Corresponding medical costs per patient were, respectively, $766, $1787 and $1122.

CONCLUSIONS

The optimal approach to managing patients following initial treatment for ulcer and H. pylori infection depends on symptom status following initial therapy. For symptomatic patients, the preferred approach is to prescribe a repeat course of antimicrobial and antisecretory therapy. For patients without symptoms following initial therapy, UBT is the preferred approach because it is associated with a threefold lower risk of symptomatic ulcer at one year, although it costs an additional $110 per patient, compared with observation.

A Leishmania homologue of receptors for activated C-kinase (LACK) induces both interferon-gamma and interleukin-10 in natural killer cells of healthy blood donors

Natural killer (NK) cells from individuals unexposed to Leishmania organisms proliferate with high interferon (IFN)-gamma secretion in response to crude Leishmania antigen preparations. In an attempt to identify the molecules that induce blood cells to proliferate and to secrete cytokines, we tested the effect of a 36-kDa Leishmania homologue of receptors for activated C-kinase (LACK) on peripheral blood mononuclear cells from unexposed individuals. Mainly CD8(+) and NK cells proliferated in response to LACK. At both the mRNA and soluble protein level, the main sources for LACK-induced IFN-gamma and interleukin (IL)-10 were T and NK cells. Furthermore, in the presence of anti-major histocompatibility complex (MHC) class II antibody, there was inhibition of LACK responses in both CD4(+) and CD16/56(+) cells, with a marked decrease in IFN-gamma but with an increase in IL-10 production. We conclude that the response to LACK is part of the response to Leishmania organisms in unexposed donors described elsewhere. That this NK-dominated response is MHC class II sensitive, whether through a direct or indirect effect, is discussed.

Investigating the role of Ca2+-binding site IV in barnacle troponin C

Two genetically engineered, recombinant versions of native barnacle troponin C (TnC) (BTnC,) were created from the bacterially expressed, recombinant, wild-type BTnC (BTnCWT) to investigate the role of the Ca(2+)-specific sites in force regulation. The mutant BTnC4- contains a single amino acid mutation in site IV which results in the inactivation of site IV Ca2+ binding; the mutant BTnCTrunc lacks the last II amino acids of the C-terminal, and hence most of site IV. Both mutant proteins, which retain an active site II, bind to native TnC-depleted myofibrillar bundles and restore approximately 40% of the tension-generating capacity, about half that seen with purified native BTnC1 or BTnC2. This observation implies that the Mg(2+)-dependent interaction with troponin I (TnI) is at a location on TnC other than the C-terminal Ca(2+)-binding sites of BTnC2. Replacement with BTnCTrunc increases the sensitivity of the myofibrillar bundle to changes in ionic strength. Decreasing the ionic strength from 0.15 to 0.075 M increased force by 34%, a value much greater that the 8% increase seen in control bundles or bundles substituted with BTnC4-. These findings implicate TnC in determining this fibre characteristic, although this cannot be simply due to the alteration in the numbers of Ca2+ ions bound by the troponin complex since both BTnC4- and BTnCTrunc bind only 1 mol Ca2+/mol protein.

Altered regulation of cardiac muscle contraction by troponin T mutations that cause familial hypertrophic cardiomyopathy

To study the effect of troponin (Tn) T mutations that cause familial hypertrophic cardiomyopathy (FHC) on cardiac muscle contraction, wild-type, and the following recombinant human cardiac TnT mutants were cloned and expressed: I79N, R92Q, F110I, E163K, R278C, and intron 16(G(1) --> A) (In16). These TnT FHC mutants were reconstituted into skinned cardiac muscle preparations and characterized for their effect on maximal steady state force activation, inhibition, and the Ca(2+) sensitivity of force development. Troponin complexes containing these mutants were tested for their ability to regulate actin-tropomyosin(Tm)-activated myosin-ATPase activity. TnT(R278C) and TnT(F110I) reconstituted preparations demonstrated dramatically increased Ca(2+) sensitivity of force development, while those with TnT(R92Q) and TnT(I79N) showed a moderate increase. The deletion mutant, TnT(In16), significantly decreased both the activation and the inhibition of force, and substantially decreased the activation and the inhibition of actin-Tm-activated myosin-ATPase activity. ATPase activation was also impaired by TnT(F110I), while its inhibition was reduced by TnT(R278C). The TnT(E163K) mutation had the smallest effect on the Ca(2+) sensitivity of force; however, it produced an elevated activation of the ATPase activity in reconstituted thin filaments. These observed changes in the Ca(2+) regulation of force development caused by these mutations would likely cause altered contractility and contribute to the development of FHC.

Investigation of a genetically engineered mutant of barnacle troponin C containing a central helix deletion

To examine the importance of the central alpha-helix of troponin C (TnC) we have bacterially expressed one of the isoforms of barnacle TnC (BTnC2), BTnCWT, but without the aspartate residue at position 80 in the central helix (BTnC80-). This manipulation is expected to produce an approximately 100 degrees axial rotation of the C-domain with respect to the N-domain, and a net charge change of -1. BTnC80- mutant was able to restore force to TnC-depleted skinned barnacle myofibrillar bundles to a greater extent than wild-type protein (approximately = 170%). Competition experiments between BTnC80- and BTnC2-4-, a mutant lacking both of the calcium-specific sites (sites II and IV), shows that deletion of a single amino acid in the central helix results in a protein with increased affinity for the thin filament and one that is bound preferentially compared to BTnC2-4- when at equimolar concentrations.

Optical spectroscopic characterization of single tryptophan mutants of chicken skeletal troponin C: evidence for interdomain interaction

The effects of metal ion binding on the optical spectroscopic properties and temperature stability of two single tryptophan mutants of chicken skeletal TnC, F78W and F154W, have been examined. The absence of tyrosine and other tryptophan residues allowed the unambiguous assignment of the spectral signal from the introduced Trp residue. Changes in the molar ellipticity values in the far-UV CD spectra of the mutant proteins on metal ion binding were similar to those of wild-type TnC suggesting that the introduction of the Trp residue had no effect on the total secondary structure content. The fluorescence and near-UV absorbance data reveal that, in the apo state, Trp-78 is buried while Trp-154 is exposed to solvent. Additionally, the highly resolved (1)L(b) band of Trp-78 seen in the near-UV absorbance and CD spectra of the apo state of F78W suggest that this residue is likely in a rigid molecular environment. In the calcium-saturated state, Trp-154 becomes buried while the solvent accessibility of Trp-78 increases. The fluorescence emission and near-UV CD of Trp-78 in the N-terminal domain were sensitive to calcium binding at the C-terminal domain sites. Measurements of the temperature stability reveal that events occurring in the N-terminal domain affect the stability of the C-terminal domain and vice versa. This, coupled with the titration data, strongly suggests that there are interactions between the N- and C-terminal domains of TnC.

Gallbladder rupture during laparoscopic cholecystectomy: does it have an effect on postoperative morbidity?

Gallbladder rupture during laparoscopic cholecystectomy is a common event that may lead to increased postoperative morbidity. To evaluate this event, we reviewed 300 cases of laparoscopic cholecystectomy. Duration of surgery and hospitalization, postoperative symptoms, wound infection, and late complications were analyzed by comparing two groups of patients, one without gallbladder rupture (A) and one with rupture (B). Gallbladder rupture was found in 40 cases (13.9%). Duration of surgery averaged 81 min for group A and 96.5 min for group B. Postoperative symptoms in the first 24 hours were present in approximately 10% of patients in both groups. Within the first 24 hours, 92.3% of patients in group A were discharged compared with 85% in group B. One patient (0.4%) in group A developed wound infection compared with 2 patients (5%) in group B (p = 0.05). To date, no patients have developed late abdominal complications associated with the procedure. Although this was a retrospective and uncontrolled study, gallbladder rupture during laparoscopic cholecystectomy was found to be associated with increased wound infections. No other significant effects on postoperative morbidity were detected.

Characterisation of a mutant of barnacle troponin C lacking Ca2+-binding sites at positions II and IV

This study investigates a mutant barnacle troponin C (TnC) protein (BTnC2-4-) in which the Ca2+-binding sites (sites II and IV) have been rendered non-functional. Eliminating Ca2+ binding at both Ca2+-binding sites of barnacle TnC did not prevent the incorporation of BTnC2-4- into TnC-depleted myofibrillar bundles, although, as expected, the mutant was not able to effect muscle regulation. We conclude that the Mg2+ involved in stabilising the interaction between TnC and TnI in the barnacle must bind at a separate location to the Ca2+-binding sites. Competition experiments between BTnC2-4- and wild-type barnacle TnC (BTnCWT) or the native isoform BTnC2 indicate that BTnC2-4- has an approximately fourfold higher affinity for barnacle TnI than BTnCWT but a lower affinity for TnI compared to BTnC2. These results indicate that disabling sites II and IV changes the affinity of BTnC2-4- for TnC-denuded barnacle myofibrils, altering the stability of the bond formed between TnC and the thin filament.

Results of the economic evaluation of the first study. A multinational prospective economic evaluation. FIRST Investigators. Flolan International Randomized Survival Trial

We present the prospective economic evaluation that served as a secondary endpoint for the FIRST study, a randomized international multicenter trial of patients with severe congestive heart failure. Although the clinical results of this study were disappointing, we demonstrated the feasibility of incorporating prospective economic evaluation in phase III clinical trials.

The role of the four Ca2+ binding sites of troponin C in the regulation of skeletal muscle contraction

In order to study the role of the Ca2+-specific sites (I and II) and the high affinity Ca2+-Mg2+ sites (III and IV) of TnC in the regulation of muscle contraction, we have constructed four mutants and the wild type (WTnC) of chicken skeletal TnC, with inactivated Ca2+ binding sites I and II (TnC1,2-), site III (TnC3-), site IV (TnC4-), and sites III and IV (TnC3,4C-). All Ca2+ binding site mutations were generated by replacing the Asp at the X-coordinating position of the Ca2+ binding loop with Ala. The binding of these mutated proteins to TnC-depleted skinned skeletal muscle fibers was investigated as well as the rate of their dissociation from these fibers. The proteins were also tested for their ability to restore steady state force to TnC-depleted fibers. We found that although the NH2-terminal mutant of TnC (TnC1,2-) bound to the TnC-depleted fibers (with a lower affinity than wild type TnC (WTnC)), it was unable to reactivate Ca2+-dependent force. This supports earlier findings that the low affinity Ca2+ binding sites (I and II) in TnC are responsible for the Ca2+-dependent activation of skeletal muscle contraction. All three COOH-terminal mutants of TnC bound to the TnC-depleted fibers, had different rates of dissociation, and could restore steady state force to the level of unextracted fibers. Although both high affinity Ca2+ binding sites (III and IV) are important for binding to the fibers, site III appears to be the primary determinant for maintaining the structural stability of TnC in the thin filament. Moreover, our results suggest an interaction between the NH2- and COOH-terminal domains of TnC, since alteration of sites I and II lowers the binding affinity of TnC to the fibers, and mutations in sites III and IV affect the Ca2+ sensitivity of force development.