A comparison of enalapril with hydralazine-isosorbide dinitrate in the treatment of chronic congestive heart failure

BACKGROUND

To define better the efficacy of vasodilator therapy in the treatment of chronic congestive heart failure, we compared the effects of hydralazine and isosorbide dinitrate with those of enalapril in 804 men receiving digoxin and diuretic therapy for heart failure. The patients were randomly assigned in a double-blind manner to receive 20 mg of enalapril daily or 300 mg of hydralazine plus 160 mg of isosorbide dinitrate daily. The latter regimen was identical to that used with a similar patient population in the effective-treatment arm of our previous Vasodilator-Heart Failure Trial.

RESULTS

Mortality after two years was significantly lower in the enalapril arm (18 percent) than in the hydralazine-isosorbide dinitrate arm (25 percent) (P = 0.016; reduction in mortality, 28.0 percent), and overall mortality tended to be lower (P = 0.08). The lower mortality in the enalapril arm was attributable to a reduction in the incidence of sudden death, and this beneficial effect was more prominent in patients with less severe symptoms (New York Heart Association class I or II). In contrast, body oxygen consumption at peak exercise was increased only by hydralazine-isosorbide dinitrate treatment (P less than 0.05), and left ventricular ejection fraction, which increased with both regimens during the 2 years after randomization, increased more (P less than 0.05) during the first 13 weeks in the hydralazine-isosorbide dinitrate group.

CONCLUSIONS

The similar two-year mortality in the hydralazine-isosorbide dinitrate arms in our previous Vasodilator-Heart Failure Trial (26 percent) and in the present trial (25 percent), as compared with that in the placebo arm in the previous trial, (34 percent) and the further survival benefit with enalapril in the present trial (18 percent) strengthen the conclusion that vasodilator therapy should be included in the standard treatment for heart failure. The different effects of the two regimens (enalapril and hydralazine-isosorbide dinitrate) on mortality and physiologic end points suggest that the profile of effects might be enhanced if the regimens were used in combination.

Three-dimensional structure of myosin subfragment-1: a molecular motor

Directed movement is a characteristic of many living organisms and occurs as a result of the transformation of chemical energy into mechanical energy. Myosin is one of three families of molecular motors that are responsible for cellular motility. The three-dimensional structure of the head portion of myosin, or subfragment-1, which contains both the actin and nucleotide binding sites, is described. This structure of a molecular motor was determined by single crystal x-ray diffraction. The data provide a structural framework for understanding the molecular basis of motility.

RAS-RAF-MEK-dependent oxidative cell death involving voltage-dependent anion channels

Therapeutics that discriminate between the genetic makeup of normal cells and tumour cells are valuable for treating and understanding cancer. Small molecules with oncogene-selective lethality may reveal novel functions of oncoproteins and enable the creation of more selective drugs. Here we describe the mechanism of action of the selective anti-tumour agent erastin, involving the RAS-RAF-MEK signalling pathway functioning in cell proliferation, differentiation and survival. Erastin exhibits greater lethality in human tumour cells harbouring mutations in the oncogenes HRAS, KRAS or BRAF. Using affinity purification and mass spectrometry, we discovered that erastin acts through mitochondrial voltage-dependent anion channels (VDACs)--a novel target for anti-cancer drugs. We show that erastin treatment of cells harbouring oncogenic RAS causes the appearance of oxidative species and subsequent death through an oxidative, non-apoptotic mechanism. RNA-interference-mediated knockdown of VDAC2 or VDAC3 caused resistance to erastin, implicating these two VDAC isoforms in the mechanism of action of erastin. Moreover, using purified mitochondria expressing a single VDAC isoform, we found that erastin alters the permeability of the outer mitochondrial membrane. Finally, using a radiolabelled analogue and a filter-binding assay, we show that erastin binds directly to VDAC2. These results demonstrate that ligands to VDAC proteins can induce non-apoptotic cell death selectively in some tumour cells harbouring activating mutations in the RAS-RAF-MEK pathway.

Mineralocorticoid action: target tissue specificity is enzyme, not receptor, mediated

Mineralocorticoid receptors, both when in tissue extracts and when recombinant-derived, have equal affinity for the physiological mineralocorticoid aldosterone and for the glucocorticoids cortisol and corticosterone, which circulate at much higher concentrations than aldosterone. Such receptors are found in physiological mineralocorticoid target tissues (kidney, parotid, and colon) and in nontarget tissues such as hippocampus and heart. In mineralocorticoid target tissues the receptors are selective for aldosterone in vivo because of the presence of the enzyme 11 beta-hydroxy-steroid dehydrogenase, which converts cortisol and corticosterone, but not aldosterone, to their 11-keto analogs. These analogs cannot bind to mineralocorticoid receptors.

Dynamics of HIV viremia and antibody seroconversion in plasma donors: implications for diagnosis and staging of primary HIV infection

OBJECTIVES

The characterization of primary HIV infection by the analysis of serial plasma samples from newly infected persons using multiple standard viral assays.

DESIGN

A retrospective study involving two sets of archived samples from HIV-infected plasma donors. (A) 435 samples from 51 donors detected by anti-HIV enzyme immunoassays donated during 1984-1994; (B) 145 specimens from 44 donors detected by p24 antigen screening donated during 1996-1998.

SETTING

Two US plasma products companies.

MAIN OUTCOME MEASURES

The timepoints of appearance of HIV-1 markers and viral load concentrations during primary HIV infection.

RESULTS

The pattern of sequential emergence of viral markers in the 'A' panels was highly consistent, allowing the definition and estimation of the duration of six sequential stages. From the 'B' panels, the viral load at p24 antigen seroconversion was estimated by regression analysis at 10 000 copies/ml (95% CI 2000-93 000) and the HIV replication rate at 0.35 log copies/ml/day, corresponding to a doubling time in the preseroconversion phase of 20.5 h (95% CI 18.2-23.4 h). Consequently, an RNA test with 50 copies/ml sensitivity would detect HIV infection approximately 7 days before a p24 antigen test, and 12 days before a sensitive anti-HIV test.

CONCLUSION

The sequential emergence of assay reactivity allows the classification of primary HIV-1 infection into distinct laboratory stages, which may facilitate the diagnosis of recent infection and stratification of patients enrolled in clinical trials. Quantitative analysis of preseroconversion replication rates of HIV is useful for projecting the yield and predictive value of assays targeting primary HIV infection.

Integrative analysis of the Caenorhabditis elegans genome by the modENCODE project

We systematically generated large-scale data sets to improve genome annotation for the nematode Caenorhabditis elegans, a key model organism. These data sets include transcriptome profiling across a developmental time course, genome-wide identification of transcription factor-binding sites, and maps of chromatin organization. From this, we created more complete and accurate gene models, including alternative splice forms and candidate noncoding RNAs. We constructed hierarchical networks of transcription factor-binding and microRNA interactions and discovered chromosomal locations bound by an unusually large number of transcription factors. Different patterns of chromatin composition and histone modification were revealed between chromosome arms and centers, with similarly prominent differences between autosomes and the X chromosome. Integrating data types, we built statistical models relating chromatin, transcription factor binding, and gene expression. Overall, our analyses ascribed putative functions to most of the conserved genome.

Safety and Efficacy of NVX-CoV2373 Covid-19 Vaccine

BACKGROUND

Early clinical data from studies of the NVX-CoV2373 vaccine (Novavax), a recombinant nanoparticle vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that contains the full-length spike glycoprotein of the prototype strain plus Matrix-M adjuvant, showed that the vaccine was safe and associated with a robust immune response in healthy adult participants. Additional data were needed regarding the efficacy, immunogenicity, and safety of this vaccine in a larger population.

METHODS

In this phase 3, randomized, observer-blinded, placebo-controlled trial conducted at 33 sites in the United Kingdom, we assigned adults between the ages of 18 and 84 years in a 1:1 ratio to receive two intramuscular 5-μg doses of NVX-CoV2373 or placebo administered 21 days apart. The primary efficacy end point was virologically confirmed mild, moderate, or severe SARS-CoV-2 infection with an onset at least 7 days after the second injection in participants who were serologically negative at baseline.

RESULTS

A total of 15,187 participants underwent randomization, and 14,039 were included in the per-protocol efficacy population. Of the participants, 27.9% were 65 years of age or older, and 44.6% had coexisting illnesses. Infections were reported in 10 participants in the vaccine group and in 96 in the placebo group, with a symptom onset of at least 7 days after the second injection, for a vaccine efficacy of 89.7% (95% confidence interval [CI], 80.2 to 94.6). No hospitalizations or deaths were reported among the 10 cases in the vaccine group. Five cases of severe infection were reported, all of which were in the placebo group. A post hoc analysis showed an efficacy of 86.3% (95% CI, 71.3 to 93.5) against the B.1.1.7 (or alpha) variant and 96.4% (95% CI, 73.8 to 99.5) against non-B.1.1.7 variants. Reactogenicity was generally mild and transient. The incidence of serious adverse events was low and similar in the two groups.

CONCLUSIONS

A two-dose regimen of the NVX-CoV2373 vaccine administered to adult participants conferred 89.7% protection against SARS-CoV-2 infection and showed high efficacy against the B.1.1.7 variant. (Funded by Novavax; EudraCT number, 2020-004123-16.).

Superior efficacy of letrozole versus tamoxifen as first-line therapy for postmenopausal women with advanced breast cancer: results of a phase III study of the International Letrozole Breast Cancer Group

PURPOSE

To compare the efficacy and tolerability of tamoxifen with that of letrozole, an oral aromatase inhibitor, with tamoxifen as first-line therapy in postmenopausal women with advanced breast cancer.

PATIENTS AND METHODS

Nine hundred seven patients were randomly assigned letrozole 2.5 mg once daily (453 patients) or tamoxifen 20 mg once daily (454 patients). Patients had estrogen receptor- and/or progesterone receptor-positive tumors, or both receptors were unknown. Recurrence during adjuvant antiestrogen therapy or within the following 12 months or prior endocrine therapy for advanced disease precluded enrollment. One prior chemotherapy regimen for metastatic disease was allowed. The primary end point was time to progression (TTP). Secondary end points included overall objective response rate (ORR), its duration, rate and duration of clinical benefit, time to treatment failure (TTF), overall survival, and tolerability.

RESULTS

TTP was significantly longer for letrozole than for tamoxifen (median, 41 v 26 weeks). Treatment with letrozole reduced the risk of progression by 30% (hazards ratio, 0.70; 95% confidence interval, 0.60 to 0.82, P =.0001). TTP was significantly longer for letrozole irrespective of dominant site of disease, receptor status, or prior adjuvant antiestrogen therapy. Similarly, TTF was significantly longer for letrozole (median, 40 v 25 weeks). ORR was higher for letrozole (30% v 20%; P =.0006), as was the rate of clinical benefit (49% v 38%; P =.001). Survival data are currently immature and not reported here. Both treatments were well tolerated.

CONCLUSION

Letrozole was significantly superior to tamoxifen in TTP, TTF, ORR, and clinical benefit rate. Our results support its use as first-line endocrine therapy in postmenopausal women with advanced breast cancer.

Tamoxifen in treatment of intraductal breast cancer: National Surgical Adjuvant Breast and Bowel Project B-24 randomised controlled trial

BACKGROUND

We have shown previously that lumpectomy with radiation therapy was more effective than lumpectomy alone for the treatment of ductal carcinoma in situ (DCIS). We did a double-blind randomised controlled trial to find out whether lumpectomy, radiation therapy, and tamoxifen was of more benefit than lumpectomy and radiation therapy alone for DCIS.

METHODS

1804 women with DCIS, including those whose resected sample margins were involved with tumour, were randomly assigned lumpectomy, radiation therapy (50 Gy), and placebo (n=902), or lumpectomy, radiation therapy, and tamoxifen (20 mg daily for 5 years, n=902). Median follow-up was 74 months (range 57-93). We compared annual event rates and cumulative probability of invasive or non-invasive ipsilateral and contralateral tumours over 5 years.

FINDINGS

Women in the tamoxifen group had fewer breast-cancer events at 5 years than did those on placebo (8.2 vs 13.4%, p=0.0009). The cumulative incidence of all invasive breast-cancer events in the tamoxifen group was 4.1% at 5 years: 2.1% in the ipsilateral breast, 1.8% in the contralateral breast, and 0.2% at regional or distant sites. The risk of ipsilateral-breast cancer was lower in the tamoxifen group even when sample margins contained tumour and when DCIS was associated with comedonecrosis.

INTERPRETATION

The combination of lumpectomy, radiation therapy, and tamoxifen was effective in the prevention of invasive cancer.

Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Appendicular skeletal muscle mass: measurement by dual-photon absorptiometry

Dual-photon absorptiometry (DPA) allows separation of body mass into bone mineral, fat, and fat-free soft tissue. This report evaluates the potential of DPA to isolate appendages of human subjects and to quantify extremity skeletal muscle mass (limb fat-free soft tissue). The method was evaluated in 34 healthy adults who underwent DPA study, anthropometry of the limbs, and estimation of whole-body skeletal muscle by models based on total body potassium (TBK) and nitrogen (TBN) and on fat-free body mass (FFM). DPA appendicular skeletal muscle (22.0 +/- 3.1 kg, mean +/- SD) represented 38.7% of FFM, with similar proportions in males and females. There were strong correlations (all p less than 0.001) between limb muscle mass estimated by DPA and anthropometric limb muscle areas (r = 0.82-0.92), TBK (r = 0.94), and total-body muscle mass based on TBK-FFM (r = 0.82) and TBK-TBN (r = 0.82) models. Appendicular skeletal muscle mass estimated by DPA is thus a potentially practical and accurate method of quantifying human skeletal muscle mass in vivo.

A placental clock controlling the length of human pregnancy

We report the existence of a 'placental clock', which is active from an early stage in human pregnancy and determines the length of gestation and the timing of parturition and delivery. Using a prospective, longitudinal cohort study of 485 pregnant women we have demonstrated that placental secretion of corticotropin-releasing hormone (CRH) is a marker of this process and that measurement of the maternal plasma CRH concentration as early as 16-20 weeks of gestation identifies groups of women who are destined to experience normal term, preterm or post-term delivery. Further, we report that the exponential rise in maternal plasma CRH concentrations with advancing pregnancy is associated with a concomitant fall in concentrations of the specific CRH binding protein in late pregnancy, leading to a rapid increase in circulating levels of bioavailable CRH at a time that coincides with the onset of parturition, suggesting that CRH may act directly as a trigger for parturition in humans.

A common open representation of mass spectrometry data and its application to proteomics research

A broad range of mass spectrometers are used in mass spectrometry (MS)-based proteomics research. Each type of instrument possesses a unique design, data system and performance specifications, resulting in strengths and weaknesses for different types of experiments. Unfortunately, the native binary data formats produced by each type of mass spectrometer also differ and are usually proprietary. The diverse, nontransparent nature of the data structure complicates the integration of new instruments into preexisting infrastructure, impedes the analysis, exchange, comparison and publication of results from different experiments and laboratories, and prevents the bioinformatics community from accessing data sets required for software development. Here, we introduce the 'mzXML' format, an open, generic XML (extensible markup language) representation of MS data. We have also developed an accompanying suite of supporting programs. We expect that this format will facilitate data management, interpretation and dissemination in proteomics research.

Regulation of p16CDKN2 expression and its implications for cell immortalization and senescence

p16CDKN2 specifically binds to and inhibits the cyclin-dependent kinases CDK4 and CDK6, which function as regulators of cell cycle progression in G1 by contributing to the phosphorylation of the retinoblastoma protein (pRB). Human cell lines lacking functional pRB contain high levels of p16 RNA and protein, suggesting a negative feedback loop by which pRB might regulate p16 expression in late G1. By a combination of nuclear run-on assays and promoter analyses in human fibroblasts expressing a temperature-sensitive simian virus 40 T antigen, we show that p16 transcription is affected by the status of pRB and define a region in the p16 promoter that is required for this response. However, the effect is not sufficient to account for the differences in p16 RNA levels between pRB-positive and -negative cells. Moreover, p16 RNA is extremely stable, and the levels do not change appreciably during the cell cycle. Primary human fibroblasts express very low levels of p16, but the RNA and protein accumulate in late-passage, senescent cells. The apparent overexpression of p16 in pRB-negative cell lines is therefore caused by at least two factors: loss of repression by pRB and an increase in the number of population doublings.

X-ray structures of the myosin motor domain of Dictyostelium discoideum complexed with MgADP.BeFx and MgADP.AlF4-

The three-dimensional structures of the truncated myosin head from Dictyostelium discoideum myosin II complexed with beryllium and aluminum fluoride and magnesium ADP are reported at 2.0 and 2.6 A resolution, respectively. Crystals of the beryllium fluoride-MgADP complex belong to space group P2(1)2(1)2 with unit cell parameters of a = 105.3 A, b = 182.6 A, and c = 54.7 A, whereas the crystals of the aluminum fluoride complex belong to the orthorhombic space group C222(1) with unit cell dimensions of a = 87.9 A, b = 149.0 A, and c = 153.8 A. Chemical modification was not necessary to obtain these crystals. These structures reveal the location of the nucleotide complexes and define the amino acid residues that form the active site. The tertiary structure of the protein complexed with MgADP.BeFx is essentially identical to that observed previously in the three-dimensional model of chicken skeletal muscle myosin subfragment-1 in which no nucleotide was present. By contrast, the complex with MgADP.AlF4- exhibits significant domain movements. The structures suggest that the MgADP.BeFx complex mimics the ATP bound state and the MgADP.AlF4- complex is an analog of the transition state for hydrolysis. The domain movements observed in the MgADP.AlF4- complex indicate that myosin undergoes a conformational change during hydrolysis that is not associated with the nucleotide binding pocket but rather occurs in the COOH-terminal segment of the myosin motor domain.

An antisense oligonucleotide against SOD1 delivered intrathecally for patients with SOD1 familial amyotrophic lateral sclerosis: a phase 1, randomised, first-in-man study

BACKGROUND

Mutations in SOD1 cause 13% of familial amyotrophic lateral sclerosis. In the SOD1 Gly93Ala rat model of amyotrophic lateral sclerosis, the antisense oligonucleotide ISIS 333611 delivered to CSF decreased SOD1 mRNA and protein concentrations in spinal cord tissue and prolonged survival. We aimed to assess the safety, tolerability, and pharmacokinetics of ISIS 333611 after intrathecal administration in patients with SOD1-related familial amyotrophic lateral sclerosis.

METHODS

In this randomised, placebo-controlled, phase 1 trial, we delivered ISIS 333611 by intrathecal infusion using an external pump over 11·5 h at increasing doses (0·15 mg, 0·50 mg, 1·50 mg, 3·00 mg) to four cohorts of eight patients with SOD1-positive amyotrophic lateral sclerosis (six patients assigned to ISIS 333611, two to placebo in each cohort). We did the randomisation with a web-based system, assigning patients in blocks of four. Patients and investigators were masked to treatment assignment. Participants were allowed to re-enrol in subsequent cohorts. Our primary objective was to assess the safety and tolerability of ISIS 333611. Assessments were done during infusion and over 28 days after infusion. This study was registered with Clinicaltrials.gov, number NCT01041222.

FINDINGS

Seven of eight (88%) patients in the placebo group versus 20 of 24 (83%) in the ISIS 333611 group had adverse events. The most common events were post-lumbar puncture syndrome (3/8 [38%] vs 8/24 [33%]), back pain (4/8 [50%] vs 4/24 [17%]), and nausea (0/8 [0%] vs 3/24 [13%]). We recorded no dose-limiting toxic effects or any safety or tolerability concerns related to ISIS 333611. No serious adverse events occurred in patients given ISIS 333611. Re-enrolment and re-treatment were also well tolerated.

INTERPRETATION

This trial is the first clinical study of intrathecal delivery of an antisense oligonucleotide. ISIS 333611 was well tolerated when administered as an intrathecal infusion. Antisense oligonucleotides delivered to the CNS might be a feasible treatment for neurological disorders.

FUNDING

The ALS Association, Muscular Dystrophy Association, Isis Pharmaceuticals.

DemTect: a new, sensitive cognitive screening test to support the diagnosis of mild cognitive impairment and early dementia

OBJECTIVES

To design a new, highly sensitive psychometric screening to identify patients with mild cognitive impairment (MCI) and patients with dementia in the early stages of the disease.

METHODS

Five tasks were included in the DemTect: a word list, a number transcoding task, a word fluency task, digit span reverse, and delayed recall of the word list. The normation was performed with 145 healthy control subjects (CG). Furthermore, 97 MCI patients and 121 patients with possible Alzheimer's disease (AD) were tested with the DemTect and the MMSE. Classification rates for both tests were analysed.

RESULTS

On the basis of the CG data, age-dependant transformation algorithms for the DemTect subtests were defined, and an education correction was provided for the total transformed score. The patient groups scored significantly below the CG in both the DemTect and the MMSE. Compared to the MMSE, classification rates of the DemTect were superior for both the MCI and the AD group, with high sensitivities of 80% and 100%, respectively.

CONCLUSIONS

The DemTect is short (8-10 minutes), easy to administer, and its transformed total score (maximum 18) is independent of age and education. The DemTect helps in deciding whether cognitive performance is adequate for age (13-18 points), or whether MCI (9-12 points) or dementia (8 points or below) should be suspected.

A candidate prostate cancer susceptibility gene at chromosome 17p

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

Measuring behavioural disturbance of elderly demented patients in the community and its effects on relatives: a factor analytic study

In recent years increasing interest has centered on the elderly psychogeriatric patient living in the community and the part played by relatives in supporting these patients. There is a need, however, for ways of assessing the behavioural disturbance shown by such patients at home and the effect this behaviour has on relatives. Ratings by relatives of the behaviour at home of elderly dementing patients attending a geriatric psychiatry day hospital, together with the relatives' own ratings of the degree of stress and upset being experienced were obtained. Using the technique of factor analysis was shown that the patient's behaviour and the relative's reaction could be analysed into a number of separate categories and that these were differentially related to each other. Thus, for example, personal distress in the relative was related mainly to the amount of apathetic and withdrawn behaviour shown by the patient, whereas negative feelings held by the relative towards the patient were related only to the degree of disturbance of the patient's mood. The construction of scales measuring these different aspects of patient's behaviour and relative's reaction is described.

Light-chain phosphorylation controls the conformation of vertebrate non-muscle and smooth muscle myosin molecules

Phosphorylation of the 20,000-molecular weight (Mr) light chains of vertebrate non-muscle (thymus) and smooth muscle (gizzard) myosins regulates the assembly of these myosins into filaments in vitro. At physiological ionic strength and pH, nonphosphorylated smooth muscle and non-muscle myosin filaments are disassembled by stoichiometric levels of MgATP, forming species having sedimentation coefficients of approximately 11S (range 10-12S; myosin monomers in high salt sediment at 6S). When the 20,000 (20K)-Mr light chains on these 11S myosin species are phosphorylated by the light-chain kinase/calmodulin-Ca2+ complex, the inhibitory effect of the light chains on filament formation is removed and the myosins reassemble into filaments which are stable in MgATP. It was originally suggested that the 11S myosin species was a dimer, previously suggested as a building block for smooth muscle and non-muscle myosin filaments. It has since been shown, however, that 11S smooth muscle myosin is monomeric and has a folded conformation rather than the extended shape characteristic of monomeric myosin in high salt. Here we show that 11S non-muscle myosin is also folded and that phosphorylation of the 20K-Mr light chains of both vertebrate non-muscle (thymus) and vertebrate smooth muscle (gizzard) myosins causes these folded 11S molecules to unfold into the conventional extended monomeric form, which is able to assemble into filaments.

Breast and ovarian cancer-specific cytotoxic T lymphocytes recognize the same HER2/neu-derived peptide

The identification of antigenic peptides presented on the tumor cell surface by HLA class I molecules and recognized by tumor-specific cytotoxic T lymphocytes may lead to a peptide vaccine capable of inducing protective cellular immunity. We demonstrate that both HLA-A2-restricted breast and ovarian tumor-specific cytotoxic T lymphocytes recognize shared antigenic peptides. At least one of these peptides is derived from the oncogene product of HER2/neu, which is overexpressed in 30-40% of all breast and ovarian cancers. T cells sensitized against this nine-amino acid sequence demonstrate significant recognition of HLA-A2+, HER2/neu+ tumors. Since 50% of the tumor-cell population is HLA-A2+ and many different tumors express HER2/neu, this peptide may be widely recognized and have many clinical applications.