Lipid vesicle aggregation induced by cooling.

Lipid bilayer fusion is a complex process requiring several intermediate steps. Initially, the two bilayers are brought into close contact following removal of intervening water layers and overcoming electrostatic repulsions between opposing bilayer head groups. In this study we monitor by light scattering the reversible aggregation of phosphatidylcholine single shell vesicles during which adhesion occurs but stops prior to a fusion process. Light scattering measurements of dimyristoyl-sn-glycero-3-phosphocholine (DMPC), dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in water show that lowering the temperature of about 0.14 micron single shell vesicles of DPPC (from 20 degrees C to 5 degrees C) and about 2 micron vesicles of DSPC (from 20 degrees C to 15 degrees C), but not of 1 micron vesicles of DMPC, results in extensive aggregation within 24 hours that is reversible by an increase in temperature. Aggregation of DSPC vesicles was confirmed by direct visual observation. Orientation of lipid head groups parallel to the plane of the bilayer and consequent reduction of the negative surface charge can account for the ability of DPPC and DSPC vesicles to aggregate. Retention of negatively charged phosphates on the surface and the burial of positively charged cholines within the bilayer offer an explanation for the failure of DMPC vesicles to aggregate. Lowering the temperature of 1,2-dipalmitoyl-sn-glycero-3-phosphoserine (DPPS) vesicles from 20 degrees C to 5 degrees C failed to increase aggregation within 24 hours at Mg(++)/DPPS ratios that begin to initiate aggregation and fusion.

Aromatase inhibitor-associated arthralgia and/ or bone pain: frequency and characterization in non-clinical trial patients.

BACKGROUND: The frequency of aromatase inhibitor (AI)-associated arthralgia and/or bone pain in clinical practice is not known. PATIENTS AND METHODS: Fifty-six consecutive patients with breast cancer not on clinical trials who were receiving AIs in a clinical practice were interviewed regarding occurrence of worsening or new arthralgia and/or bone pain after starting AI therapy. The occurrence, character, severity, and resolution of pain were evaluated. RESULTS: Arthralgia and/or bone pain was reported in 61% of patients. It was severe in 30%, continuous in 41%, central in 50%, peripheral in 79%, and resulted in discontinuation of the drug in 20% of patients. Effective therapies in controlling pain were acetaminophen, 29%; nonsteroidal anti-inflammatory drugs, 50%; opiates, 18%, and glucosamine in 15% of patients. Despite this, 20% of patients discontinued AI therapy because of pain. CONCLUSION: Aromatase inhibitor-associated pain is more frequent in patients not in clinical trials than previously appreciated in clinical trials. Improved patient education is needed, and prompt therapeutic management of pain is required to ensure continued drug treatment and improved quality of life.

NMR structure of a parallel-stranded DNA duplex at atomic resolution.

DNA dodecamers have been designed with two cytosines on each end and intervening A and T stretches, such that the oligomers have fully complementary A:T base pairs when aligned in the parallel orientation. Spectroscopic (UV, CD and IR), NMR and molecular dynamics studies have shown that oligomers having the sequences d(CCATAATTTACC) and d(CCTATTAAATCC) form a parallel-stranded duplex when dissolved at 1:1 stoichiometry in aqueous solution. This is due to the C:C+ clamps on either end and extensive mismatches in the antiparallel orientation. The structure is stable at neutral and acidic pH. At higher temperatures, the duplex melts into single strands in a highly cooperative fashion. All adenine, cytosine and thymine nucleotides adopt the anti conformation with respect to the glycosidic bond. The A:T base pairs form reverse Watson-Crick base pairs. The duplex shows base stacking and NOEs between the base protons T(H6)/A(H8) and the sugar protons (H1'/H2'/H2") of the preceding nucleotide, as has been observed in antiparallel duplexes. However, no NOEs are observed between base protons H2/H6/H8 of sequential nucleotides, though such NOEs are observed between T(CH3) and A(H8). A three-dimensional structure of the parallel-stranded duplex at atomic resolution has been obtained using molecular dynamics simulations under NMR constraints. The simulated structures have torsional angles very similar to those found in B-DNA duplexes, but the base stacking and helicoid parameters are significantly different.

Surgical and radiation therapy management of recurrent anal melanoma.

BACKGROUND: Melanoma of the anorectal mucosa is a rare but highly aggressive tumor. Its presenting symptoms are frequently confused with hemorrhoids, thereby causing a delay in diagnosis. Anorectal melanoma carries with it a very poor prognosis. There is a paucity of data investigating management options for anorectal melanoma, and even fewer data reporting recurrent or refractory cases. CASE PRESENTATION: This case documents a 41-year-old female with a long history of hemorrhoids presenting with anorectal discharge. She was incidentally found have anorectal melanoma following surgical resection. Systemic diagnostic work-up demonstrated PET-avid lymphadenopathy in her right groin. She underwent right groin dissection. However, seven months later she recurred in her right groin and a new recurrent mass was found in her pelvis. She underwent a second groin dissection and resection of the pelvic recurrence. This was followed by a course of hypofractionated radiation therapy then systemic immunotherapy. DISCUSSION: Surgery has been the mainstay of treatment. However, the extent of surgery has been the topic of investigation. Historically, radical resections have been performed but they result in high rates of post-operative morbidity. Newer studies have compared radical resection with wide local excisions and found comparable outcomes. Anorectal melanoma is frequently a systemic disease. The ideal systemic therapy regimen has not yet been determined but numerous studies show a benefit to multi-agent treatments. Radiation therapy is typically given in the post-operative or palliative setting. CONCLUSIONS: Anorectal mucosal melanoma is a very rare but aggressive disease with a poor prognosis. The overall treatment goal should strive to optimize quality of life and tumor control while minimizing treatment-related morbidities.

Clinico-pathologic relevance of Survivin splice variant expression in cancer.

Survivin is a member of the inhibitor of apoptosis (IAP) family and has multifunctional properties that include aspects of proliferation, invasion and cell survival control. Survivin is a promising candidate for targeted cancer therapy as its expression is associated with poor clinical outcome, more aggressive clinico-pathologic features, and resistance to radiation and chemotherapy. In the present review the different properties of the Survivin splice variants are discussed and their activities correlated with different aspects of cancer cell biology, to include subcellular location. Special emphasis is placed on our current understanding of these Survivin splice variants influence on each other and on the phenotypic responses to therapy that they may control.

The stabilizing contribution of thymine in duplexes of (dA)24 with (dU)24, (dT)24, (dU12-dT12), (dU-dT)12, (dU2-dT2)6, or (dU3-dT3)4: nearest neighbor and next-nearest neighbor effects.

Ultraviolet melting curves are used to determine the effect of the pyrimidine 5-methyl group on the stability of duplexes of (dA)(24) with (dU)(24), (dT)(24), (dU(12)-dT(12)), (dU-dT)(12), (dU(2)-dT(2))(6), and (dU(3)-dT(3))(4). Substitution of a T for a U results in an increase in stability, which is attributed to an increase in strength of dipole-induced dipole and dispersion (van der Waals) interactions. Significant additional enhancement occurs when two T residues are adjacent. A further increase in the number of adjacent T's has a relatively slight effect on T(m). The sequence effect appears to be largely attributable to an increment in dispersion forces. The CD spectra of the duplexes are all closely similar except in the region between 260 and 290 nm. A band near 272 nm associated with the presence of U in the spectrum of (dA)(24).(dU)(24) decreases in intensity when T's are incorporated in the pyrimidine strand. The band is completely replaced in the spectrum of (dA)(24).(dT)(24) with a new maximum at 282 nm and a minimum at 268 nm, both of lower magnitude. The emergence of the two new bands is correlated with the presence of adjacent T's once more, and only two adjacent T's appear necessary for a major part of the change to occur. The degree of cation release on thermal dissociation of the oligomer dimers ranges from Deltai = 0.14 to 0.16, about the same or slightly less than values reported for polynucleotide duplexes and less than predicted from theoretical calculations.

The thermodynamic contribution of the 5-methyl group of thymine in the two- and three-stranded complexes formed by poly(dU) and poly(dT) with poly(dA).

To assess the thermodynamic contribution of the 5-methyl group of thymine, we have studied the two-stranded helical complexes poly(dA).poly(dU) and poly(dA).poly(dT) and the three-stranded complexes--poly(dA).2poly(dU), poly(dA).poly(dT).poly(dU) and poly(dA).2poly(dT)--by differential scanning calorimetry, and uv optical melting experiments. The thermodynamic quantities associated with the 3 --> 2, 2 --> 1, and 3 --> 1 melting transitions are found to vary with salt concentration and temperature in a more complex manner than commonly believed. The transition temperatures, T(m), are generally not linear in the logarithm of concentration or activity of NaCl. The change in enthalpy and in entropy upon melting varies with salt concentration and temperature, and a change in heat capacity accompanies each transition. The poly(dA).2poly(dU) triple helix is markedly different from poly(dA).2poly(dT) in both its CD spectrum and thermodynamic behavior, while the poly(dA).poly(dT).poly(dU) triple helix resembles poly(dA).2poly(dT) in these properties. In comparing poly(dA).2poly(dT) with either the poly(dA).poly(dT).poly(dU) or the poly(dA).2poly(dU) triplexes, the substitution of thymine for uracil in the third strand results in an enhancement of stability against the 3 --> 2 dissociation of deltadeltaG degrees = -135 +/- 85 cal (mol A)(-1) at 37 degrees C. This represents a doubling of the absolute stability toward dissociation compared to the triplexes with poly(dU) as the third strand. The poly (dA).poly (dT) duplex is more stable than poly(dA).poly(dU) by deltadeltaG degrees = -350 +/- 60 cal (mol base pair)(-1) at 37 degrees C. Poly(dA).poly(dT) has 50% greater stability than poly(dA).poly(dU) as a result of the dT for dU substitution in the duplex.

Therapeutic efficacy and safety of platelets treated with a photochemical process for pathogen inactivation: the SPRINT Trial.

We report a transfusion trial of platelets photochemically treated for pathogen inactivation using the synthetic psoralen amotosalen HCl. Patients with thrombocytopenia were randomly assigned to receive either photochemically treated (PCT) or conventional (control) platelets for up to 28 days. The primary end point was the proportion of patients with World Health Organization (WHO) grade 2 bleeding during the period of platelet support. A total of 645 patients (318 PCT and 327 control) were evaluated. The primary end point, the incidence of grade 2 bleeding (58.5% PCT versus 57.5% control), and the secondary end point, the incidence of grade 3 or 4 bleeding (4.1% PCT versus 6.1% control), were equivalent between the 2 groups (P =.001 by noninferiority). The mean 1-hour posttransfusion platelet corrected count increment (CCI) (11.1 x 10(3) PCT versus 16.0 x 10(3) control), average number of days to next platelet transfusion (1.9 PCT versus 2.4 control), and number of platelet transfusions (8.4 PCT versus 6.2 control) were different (P <.001). Transfusion reactions were fewer following PCT platelets (3.0% PCT versus 4.4% control; P =.02). The incidence of grade 2 bleeding was equivalent for PCT and conventional platelets, although posttransfusion platelet count increments and days to next transfusion were decreased for PCT compared with conventional platelets.