Maximum Phosphorylation of the Cardiac Ryanodine Receptor at Serine-2809 by Protein Kinase A Produces Unique Modifications to Channel Gating and Conductance Not Observed at Lower Levels of Phosphorylation

It is suggested that protein kinase A (PKA)-dependent phosphorylation of cardiac ryanodine receptors (RyR2) is linked to the development of heart failure and the generation of fatal cardiac arrhythmias. It is also suggested that RyR2 is phosphorylated to 75% of maximum levels in heart failure resulting in leaky, unregulated channels gating in subconductance states. We now demonstrate that this is unlikely, as RyR2 isolated from nonfailing cardiac muscle is phosphorylated to 75% of maximum at serine-2809, and in this situation, RyR2 displays low open probability (P(o)) (0.059+/-0.010 [SEM]; n=30) and normal regulation of gating by Ca(2+) and other ligands. However, when serine-2809 is PKA phosphorylated to maximum levels on RyR2, unique changes in channel behavior are observed. The channel displays enhanced single-channel conductance, very long open states causing large increases in P(o), and no evidence of subconductance states. Dephosphorylation of channels by protein phosphatase 1 (from 75% to near 0% at serine-2809) also enhances RyR2 channel activity through abbreviation of closed lifetimes. We propose that channels phosphorylated to 75% of maximum at serine-2809 occupy a natural low point in the RyR2 activity landscape. This optimizes channel control, which can be accomplished either by enhanced or decreased phosphorylation, making the channel particularly sensitive to the kinase:phosphatase balance. Pathological situations such as heart failure might upset this balance and thereby permit prolonged stoichiometric phosphorylation of serine-2809, which would be required for dysregulation of SR Ca(2+) release.

High level analysis of genomic data reveals complex predictors of response to trastuzumab (T) and chemotherapy for early stage breast cancer

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Background: Trastuzumab (T) with chemotherapy has been shown to improve survival in breast cancer patients but de novo resistance is common. Identifying predictors of response to T in primary cancers may lead to an understanding of mechanisms of resistance. We investigated whether combined microarray datasets from patients with early breast cancer treated with preoperative T and chemotherapy could predict for response to therapy. Methods: Two cohorts of patients with HER2 3+/FISH+, stage II-III breast cancer were included in this analysis: trial 1- T and docetaxel (n=38), trial 2 -T and vinorelbine (n=48), both for 12 weeks. Frozen tissue core biopsies were available and successfully amplified in 41 patients (trial 1: 20, trial 2: 21 patients), with standard sample processing, RNA extraction, amplification and hybridization to Affymetrix U133 chips. Differential expression of genes and chromosomal regions, (defined as >10 genes in a given chromosomal cytoband), between patients with pathologic complete response (pCR) vs. those with residual invasive disease were examined. A measure of total functional aneuploidy (tFA) was calculated by summing net deviation in expression of all chromosomal regions and a gene expression signature of genomic instability (CIN) was derived by the identification of genes showing a high level of correlation with tFA . Results: By unsupervised hierarchical analysis, both datasets interdigitated suggesting no inherent bias. Gene expression patterns of individual genes showed weak associations with pCR. However, distinct statistically significant chromosomal regions, Chr2p23 Chr6q24 Chr7q33 Chr2p2 Chr12q21.31 Chr14q32.2 Chr1p34.2 Chr8q21.3, were associated with pCR to T therapy (p<0.005), and were confirmed in more than 50% samples by SNP analysis. In addition, resistant tumors showed higher levels of the CIN signature (p<0.005). Conclusions: We have shown that gene expression data can be merged and used for discovery predictive chromosomal regions associated T response. In addition, chromosomal instability was associated with T resistance. If validated, these distinct dysregulated chromosomal regions may serve as predictive markers of response to trastuzumab therapy.

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Results of phase I clinical trials of Coramsine in patients with advanced solid tumors

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Background: Coramsine (C) is a 1:1 mixture of solasonine and solamargine, plant glycoalkaloids found in the species Solanum Linneanum, with single agent and synergistic combination in vitro and in vivo preclinical efficacy in various tumor models through interaction with rhamnose-containing cell membrane glycoproteins and subsequent internalization. Methods: C initially as a 2-hr IV infusion daily × 5 every 2 weeks to define the MTD, recommended Phase II dose, toxicity and pharmacokinetics. Based on preclinical toxicology the infusion duration was increased to 4 hours and 24 hours (120 hr continuous infusion). Doses studied range from 0.75 mg/kg/day to 3.0 mg/kg/day. Results: 27 pts were treated. DLT occurred in 2/2 pts at 1.5 mg/kg/day (2 hr) and 2/2 pts each at 3.0 mg/kg/day (4 hr and 24 hr). Preceding dose levels 1.0 mg/kg (2 hr) and 1.5 mg/kg (4 hr) produced DLT in 2/6 pts each with no grade IV. Over 24 hr, 2.25 mg/kg/day produced DLT in 4/6 patients. Limiting toxicity at all schedules was grade III/IV transaminitis with grade I-III increases of bilirubin and grade I-II creatinine. Hepatotoxicity was maximal at days 3–5, resolved over 10–21 days, was clinically asymptomatic apart from grade I-II fatigue, and was not cumulative. No myelosuppression or other serious drug-related toxicity was recorded. Partial responses were documented in 2 pts (renal, NSCLC) and minor response in 1 pt with unknown primary. Responses were seen using both 2 hr and 4 hr infusions. Pharmacokinetic parameters for solasonine and solamargine are linear across the narrow range of doses studied with elimination T1/2 of 5.57 ± 1.27 hr (solasonine), 8.40 ± 2.00 hr (solamargine) and Cl of 5.6 ± 1.6 L/hr (solasonine), 3.0 ± 0.7 L/hr (solamargine). Peak levels of both exceed active in vitro levels (>2,000 ng/ml). Conclusions: Coramsine produces dose-limiting hepatotoxicity at doses above 1.0 mg/kg/day over 2 hours or 1.5 mg/kg/day over 4 hours. 2.25 mg/kg/day over 24 hours exceeds the MTD. Activity has been seen against resistant solid tumors. Phase II studies in renal cancer and melanoma will be performed using 1.5 mg/kg/day over 4 hours.

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Case report:DNA testing resolves unusual results in the Dombrock system

Typing for antigens in the Dombrock blood group system and identifying the corresponding antibodies are notoriously difficult tasks. The reagents are scarce and the antibodies are weakly reactive. When RBCs from family members of a patient with an antibody to a high-prevalence Dombrock antigen were tested for compatibility,an unusual pattern of inheritance was observed:RBCs from the patient's children and one niece, in addition to those from some of the patient's siblings,were compatible. This prompted the performance of DNA-based assays for DO alleles and the results obtained were consistent with and explained the compatibility test results. It was possible to study this large kindred because of the cooperation of family members, hospital personnel, and reference laboratory staff.

The use of prostheses in skeletally immature patients

Prosthetic reconstruction in the skeletally immature patient is challenging because of the necessity to cope with expected disruption of limb growth after resection of one or more major growth plates and the high demands placed on implants by young patients. Although prosthetic reconstruction in children is fraught with many problems, it is usually possible to obtain a good functional limb at skeletal maturity. Extendable prostheses are readily acceptable to patients and their parents. The availability of noninvasive extendable prostheses is expected to lead to fewer complications, fewer surgical interventions, and even improved function. This article reviews the indication, evolution, and clinical and functional results of extendable endoprostheses, drawing from experience in the last 30 years of using such prostheses in children.

An evaluation of the change in activity and workload arising from diabetic ophthalmology referrals following the introduction of a community based digital retinal photographic screening programme

AIMS

To determine how the workload of an ophthalmology department changed following the introduction of an organised retinal screening programme.

METHODS

Information was collected from the hospital medical record of people with diabetes attending eye clinics over 4 years. The first year was before screening, the next 2 years the first round, and the fourth year the second round.

RESULTS

The total number of people with diabetes referred each year over the 4 year period was 853, 954, 974, 1051 consecutively. The number of people with diabetes in the county rose by 1400 per annum. The total number of referrals for an opinion about diabetic retinopathy was 227, 333, 363, 368, for cataract was 64, 57, 77, 93, and for glaucoma was 57, 62, 61, 68. The total number of patients referred for laser treatment over the 4 years was 77, 124, 111, and 63

CONCLUSION

This study suggests that the workload in the eye clinic increases in the first round of screening but in subsequent rounds it does not fall below the pre-screening level, except for laser treatment. This may be partly because of increasing numbers of people with diabetes. With the introduction of a national screening programme, this has significant workload implications for the National Health Service.

Serosurvey for canine distemper virus exposure in dogs in communal lands in Zimbabwe

Sera from 173 apparently healthy, unvaccinated dogs from 4 widely separated communal lands in Zimbabwe were tested by ELISA for antibodies against canine distemper virus. Overall, 82% were positive with high prevalences found in each communal land. The highest seroprevalence was in dogs between 1 and 2 years of age (91%; 49/54). These results show dogs in the communal lands of Zimbabwe are commonly exposed to canine distemper virus and that a substantial number survive infection. The role that the virus might play in the high mortality rate of the dog population on communal land warrants further investigation.

Economic analysis of unrelated allogeneic bone marrow transplantation: results from the randomized clinical trial of T-cell depletion vs unmanipulated grafts for the prevention of graft-versus-host disease

Unrelated-donor marrow transplantation is a potential option for transplant candidates lacking a compatible related donor. The T-cell Depletion Study compared the 3-year disease-free survival for patients receiving T-cell-depleted (TCD) donor marrow (n = 203) vs unmanipulated donor marrow with methotrexate and cyclosporine (M/C) (n = 207). Hospital costs during index admission were documented with billing data, while hospital costs during subsequent 6-month follow-up were estimated from case report forms. Patients with index admission billing were included in the analysis (TCD = 119, M/C = 127). Total hospital length of stay (LOS) was similar across groups, with medians 47.0 days for TCD and 52.0 days for M/C (P = 0.72). Total hospital costs were comparable, 145,115 dollars vs 141,981 dollars (P = 0.63) for TCD and M/C, respectively. However, controlling for site and patient characteristics, TCD was associated with a 12.1% reduction in LOS for the index admission (95% CI -19.4%, -4.3%). Independent of treatment, HLA matching (6/6) was associated with an 8.6% (95% CI -17.4%, +1.2%) reduction in the index admission LOS, while cost was lower by 15.8% (95% CI -26.7%, -3.3%). Treatment costs were similar for TCD and M/C study groups. Savings on reduced cost for treating acute graft-versus-host disease were likely offset by increase in serious infections in the TCD arm.

'Referral into a void': opinions of general practitioners and others on single point of access to mental health care

In the past, British general practitioners (GPs) have referred patients to individual consultants. There is now a trend towards generic referral, whereby the specialist team is consulted via a single point of access. We examined the impact of this innovation on the relationship between GPs and specialists in mental health care. Sixteen groups of randomly selected GPs and mental health professionals (MHPs) in England discussed clinical scenarios involving the use of mental health interventions for patients with functional somatic symptoms. The meetings were audiotaped, transcribed and analysed to the point at which no major new themes were emerging. The final analysis was confined to a purposive sample of six of the sixteen groups, comprising 54 GPs and 15 MHPs. Although the rationale for the single point of access was clear to both GPs and MHPs, the approach erected boundaries because it impeded the establishment of professional relationships and transfer of knowledge. GPs thought the system reduced their capacity to be accountable to their patients and limited the potential for their own professional development. MHPs did not seem to be aware of GPs' concerns. Effective interprofessional management of individual patients depends upon confidence in colleagues' skills and good communication. Factors that hamper these must be addressed in the development of this system of referral.

Met receptor dynamics and signalling

The receptor for hepatocyte growth factor (HGF), Met, controls a programme of invasive growth that combines proliferation with various moto- and morphogenetic processes. This process is important for development and organ regeneration, but dysregulation in transformed tissues can contribute to cancer progression and metastasis. Acute stimulation of tissue culture cells with HGF leads to Met downregulation via degradation through an endocytic mechanism that also requires proteasome activity. Perturbation of Met trafficking on the endocytic pathway, either at the level of the internalisation step or during sorting at the early endosome, leads to altered signalling outputs. Ubiquitination of Met through the E3-ligase Cbl is required for receptor downregulation, and a mutant receptor defective in Cbl binding is able to transform cells. We discuss the hypothesis that some naturally occurring Met mutants implicated in cancer may transform cells owing to defects in their trafficking along the endosomal degradation pathway.

Management and outcome after local recurrence of osteosarcoma

We report on the management and outcome of 96 patients who developed local recurrence (LR) after having definitive primary treatment with chemotherapy and surgery for non-metastatic osteosarcoma. LR developed at a median of 11 months from initial surgical treatment. 18% of patients had metastases prior to the diagnosis of LR and 23% were found to have metastases synchronously. The prognosis for this group with metastases was 14% survival at 2 years. In the 57 patients without metastases at the time of development of LR, survival was 51% at 2 years and 41% at 5 years. Treatment was by excision of the LR and radiotherapy or by amputation. The only significant prognostic factors identified were the presence of metastases at the time of development of LR (P < 0.0001) and small size of the LR. The role of adjuvant chemotherapy was unclear. Whilst every attempt should be made to avoid LR, patients who develop LR are curable, particularly if they do not have metastases at the time of diagnosis of the LR.

Polymorphisms of the equine major histocompatibility complex class II DRA locus

The full extent of the polymorphism of ELA-DRA in Equidae is not yet known. Given the apparent differences in DRA polymorphisms between Equidae and other species, the aims of this study were to more fully characterize ELA-DRA, determine the extent of gene polymorphism and establish the allele-frequency distribution. An allele reference panel for the second exon of ELA-DRA was established by sequence-based typing of 69 equine DNA samples consisting of various breeds of domestic horse (Equus caballus), together with donkeys (Equus asinus), Grant's zebras (Equus boehmi) and one onager (Equus hemionus). Five of the six previously reported alleles detected using single-strand conformation polymorphism were found: ELA-DRA*0101, ELA-DRA*0201, ELA-DRA*0301, ELA-DRA*0501 (Albright-Fraser DG et al. Polymorphism of DRA among equids. Immunogenetics 1996: 43: 315-7) and ELA-DRA*0601 (GenBank accession number AF5419361). In addition to the previously reported alleles, five novel ELA-DRA alleles were detected within the ELA-DRA allele reference panel. One of these was identified in E. caballus (ELA-DRA*JBH11), one in E. boehmi and E. hemionus (ELA-DRA*JBZ185) and three in E. asinus (ELA-DRA*JBD3, ELA-DRA*JBD17 and ELA-DRA*JBH45). A total of 565 equine DNA samples were screened using reference-strand-mediated conformation analysis, a double-stranded conformation-based mutation detection system that can be used to type existing ELA-DRA alleles and identify new variants. Based on our findings, at least 11 ELA-DRA alleles are now known to exist, and this level of polymorphism at the DRA locus appears to be unique to the genus Equus. Both the previously reported alleles and the new alleles displayed a species-specific distribution.

Experimental and theoretical study of the infrared spectra of BrHI− and BrDI−

Gas phase vibrational spectra of BrHI- and BrDI- have been measured from 6 to 17 microm (590-1666 cm(-1)) using tunable infrared radiation from the free electron laser for infrared experiments in order to characterize the strong hydrogen bond in these species. BrHI-.Ar and BrDI-.Ar complexes were produced and mass selected, and the depletion of their signal due to vibrational predissociation was monitored as a function of photon energy. Additionally, BrHI- and BrDI- were dissociated into HBr (DBr) and I- via resonant infrared multiphoton dissociation. The spectra show numerous transitions, which had not been observed by previous matrix studies. New ab initio calculations of the potential-energy surface and the dipole moment are presented and are used in variational ro-vibrational calculations to assign the spectral features. These calculations highlight the importance of basis set in the simulation of heavy atoms such as iodine. Further, they demonstrate extensive mode mixing between the bend and the H-atom stretch modes in BrHI- and BrDI- due to Fermi resonances. These interactions result in major deviations from simple harmonic estimates of the vibrational energies. As a result of this new analysis, previous matrix-isolation spectra assignments are reevaluated.