The Hubbard model within the equations of motion approach

The Hubbard model has a special role in Condensed Matter Theory as it is considered as the simplest Hamiltonian model one can write in order to describe anomalous physical properties of some class of real materials. Unfortunately, this model is not exactly solved except for some limits and therefore one should resort to analytical methods, like the Equations of Motion Approach, or to numerical techniques in order to attain a description of its relevant features in the whole range of physical parameters (interaction, filling and temperature). In this manuscript, the Composite Operator Method, which exploits the above mentioned analytical technique, is presented and systematically applied in order to get information about the behavior of all relevant properties of the model (local, thermodynamic, single- and two- particle ones) in comparison with many other analytical techniques, the above cited known limits and numerical simulations. Within this approach, the Hubbard model is shown to be also capable to describe some anomalous behaviors of the cuprate superconductors.Comment: 232 pages, more than 300 figures, more than 500 reference

Enrolling adolescents in HIV vaccine trials: reflections on legal complexities from South Africa

<p>Abstract</p> <p>Background</p> <p>South Africa is likely to be the first country in the world to host an adolescent HIV vaccine trial. Adolescents may be enrolled in late 2007. In the development and review of adolescent HIV vaccine trial protocols there are many complexities to consider, and much work to be done if these important trials are to become a reality.</p> <p>Discussion</p> <p>This article sets out essential requirements for the lawful conduct of adolescent research in South Africa including compliance with consent requirements, child protection laws, and processes for the ethical and regulatory approval of research.</p> <p>Summary</p> <p>This article outlines likely complexities for researchers and research ethics committees, including determining that trial interventions meet current risk standards for child research. Explicit recommendations are made for role-players in other jurisdictions who may also be planning such trials. This article concludes with concrete steps for implementing these important trials in South Africa and other jurisdictions, including planning for consent processes; delineating privacy rights; compiling information necessary for ethics committees to assess risks to child participants; training trial site staff to recognize when disclosures trig mandatory reporting response; networking among relevant ethics commitees; and lobbying the National Regulatory Authority for guidance.</p

Glycosylation of Erythrocyte Spectrin and Its Modification in Visceral Leishmaniasis

Using a lectin, Achatinin-H, having preferential specificity for glycoproteins with terminal 9-O-acetyl sialic acid derivatives linked in α2-6 linkages to subterminal N-acetylgalactosamine, eight distinct disease-associated 9-O-acetylated sialoglycoproteins was purified from erythrocytes of visceral leishmaniaisis (VL) patients (RBCVL). Analyses of tryptic fragments by mass spectrometry led to the identification of two high-molecular weight 9-O-acetylated sialoglycoproteins as human erythrocytic α- and β-spectrin. Total spectrin purified from erythrocytes of VL patients (spectrinVL) was reactive with Achatinin-H. Interestingly, along with two high molecular weight bands corresponding to α- and β-spectrin another low molecular weight 60 kDa band was observed. Total spectrin was also purified from normal human erythrocytes (spectrinN) and insignificant binding with Achatinin-H was demonstrated. Additionally, this 60 kDa fragment was totally absent in spectrinN. Although the presence of both N- and O-glycosylations was found both in spectrinN and spectrinVL, enhanced sialylation was predominantly induced in spectrinVL. Sialic acids accounted for approximately 1.25 kDa mass of the 60 kDa polypeptide. The demonstration of a few identified sialylated tryptic fragments of α- and β-spectrinVL confirmed the presence of terminal sialic acids. Molecular modelling studies of spectrin suggest that a sugar moiety can fit into the potential glycosylation sites. Interestingly, highly sialylated spectrinVL showed decreased binding with spectrin-depleted inside-out membrane vesicles of normal erythrocytes compared to spectrinN suggesting functional abnormality. Taken together this is the first report of glycosylated eythrocytic spectrin in normal erythrocytes and its enhanced sialylation in RBCVL. The enhanced sialylation of this cytoskeleton protein is possibly related to the fragmentation of spectrinVL as evidenced by the presence of an additional 60 kDa fragment, absent in spectrinN which possibly affects the biology of RBCVL linked to both severe distortion of erythrocyte development and impairment of erythrocyte membrane integrity and may provide an explanation for their sensitivity to hemolysis and anemia in VL patients

Immunoprotectivity of HLA-A2 CTL Peptides Derived from Respiratory Syncytial Virus Fusion Protein in HLA-A2 Transgenic Mouse

Identification of HLA-restricted CD8+ T cell epitopes is important to study RSV-induced immunity and illness. We algorithmically analyzed the sequence of the fusion protein (F) of respiratory syncytial virus (RSV) and generated synthetic peptides that can potentially bind to HLA-A*0201. Four out of the twenty-five 9-mer peptides tested: peptides 3 (F33–41), 13 (F214–222), 14 (F273–281), and 23 (F559–567), were found to bind to HLA-A*0201 with moderate to high affinity and were capable of inducing IFN-γ and IL-2 secretion in lymphocytes from HLA-A*0201 transgenic (HLA-Tg) mice pre-immunized with RSV or recombinant adenovirus expressing RSV F. HLA-Tg mice were immunized with these four peptides and were found to induce both Th1 and CD8+ T cell responses in in vitro secondary recall. Effector responses induced by these peptides were observed to confer differential protection against live RSV challenge. These peptides also caused better recovery of body weight loss induced by RSV. A significant reduction of lung viral load was observed in mice immunized with peptide 23, which appeared to enhance the levels of inflammatory chemokines (CCL17, CCL22, and IL-18) but did not increase eosinophil infiltration in the lungs. Whereas, significant reduction of infiltrated eosinophils induced by RSV infection was found in mice pre-immunized with peptide 13. Our results suggest that HLA-A2-restricted epitopes of RSV F protein could be useful for the development of epitope-based RSV vaccine

Efficacy of Major Plant Extracts/Molecules on Field Insect Pests

Insect pests are considered the major hurdle in enhancing the production and productivity of any farming system. The use of conventional synthetic pesticides has led to the emergence of pesticide-resistant insects, environmental pollution, and negative effects on natural enemies, which have caused an ecological imbalance of the predator-prey ratio and human health hazards; therefore, eco-friendly alternative strategies are required. The plant kingdom, a rich repertoire of secondary metabolites, can be tapped as an alternative for insect pest management strategies. A number of plants have been documented to have insecticidal properties against various orders of insects in vitro by acting as antifeedants, repellents, sterilant and oviposition deterrents, etc. However, only a few plant compounds are applicable at the field level or presently commercialised. Here, we have provided an overview of the broad-spectrum insecticidal activity of plant compounds from neem, Annona, Pongamia, and Jatropha. Additionally, the impact of medicinal plants, herbs, spices, and essential oils has been reviewed briefl

Concurrent chemo-irradiation using accelerated concomitant boost radiation therapy in loco-regionally advanced head and neck squamous cell carcinomas

Purpose: To investigate the feasibility of combining concomitant boost-accelerated radiation regimen (ACB) with full-dose mono-chemotherapy using cisplatin and to assess its local response and acute toxicity patterns in patients with advanced loco-regional head and neck squamous cell carcinoma (HNSCC). Materials and Methods: Between July 2004 and August 2005, a pilot study involving 27 patients with stage III to IVB (AJCC-6th) HNSCC of the oropharynx, hypopharynx and larynx who met the eligibility criteria was undertaken. Twenty-four of these patients (median age - 53 years) were analyzable. The radiation dose was 72 Gy in 42 fractions over 6 weeks, delivered in one daily fraction of 1.8 Gy during the first 3.5 weeks and two fractions per day, 1.8 Gy and 1.5 Gy boost-separated by &gt; 6 h interval, during the last 2.5 weeks. cisplatin, 100 mg/m2, was given in intravenous (i.v.) infusion on day 1 and day 22. Tumor and clinical status were assessed and acute toxicities were graded. Results: Out of 27 patients, 24 patients received both radiation and chemotherapy as per protocol and were available for analysis. The loco-regional response rates were as follows: an overall response of 95.8% (23 patients), a complete response of 79.1% (19 patients), a partial response of 16.7% (4 patients) and progressive disease in 4.2% (1 patient). Dysphagia, nausea, vomiting and bone marrow suppression were the most common side effects and were associated with cisplatin administration. One patient (3.7%) died of complications (pneumonia and sepsis), 3 patients (12.5%) had acute grade 4 toxicity and 21 patients (87.5%) had acute grade 3 (17 patients) or grade 2 (4 patients) toxicity. Conclusion: This data shows that it is feasible to combine ACB and full-dose mono-chemotherapy using cisplatin with manageable, although substantial, toxicity. The compliance to therapy was high and the loco-regional response achieved compared favorably with ACB alone or other concurrent chemoradiation regimens using standard or altered fractionation regimens tested by the Institute. It also compares well with the available literature. An extended phase II trial; and a new phase III trial, comparing ACB plus cisplatin against standard radiation plus cisplatin, are being planned at the Institute to determine whether the use of ACB in the concurrent chemoradiation setting further improves outcome