Hydrophobic similarity between molecules: a MST-based hydrophobic similarity index

A similarity index based on the hydrophilic/hydrophobic properties of molecules is presented. Such an index is defined based on the fractional partition of the free energy of solvation developed within the framework of the self-consistent reaction field MST model, which divides the free energy of solvation or the free energy of transfer into contributions assigned to the surface elements defining the solute/solvent interface. These surface contributions can be integrated to derive atomic or group contributions. The suitability of the index to compute the molecular similarity based on hydrophobic/hydrophilic properties is examined by considering their application in a variety of test systems, including structure-activity relationships, absorption properties, and molecular recognition. The similarity index is expected to be a very powerful tool in molecular similarity studies for compounds of chemical, biochemical, and pharmaceutical interest.

[Short term synaptic plasticity]

INTRODUCTION

At many chemical synapses, the amount of transmitter released by each action potential can increase or decrease markedly after the onset of specific temporal patterns of activity.

OBJECTIVES

This review focuses on mechanisms and functions of short term presynaptic plasticity that last from milliseconds to minutes. The short term enhancement of neurotransmitter release is due to three calcium dependent presynaptic processes differing in their durations: about one second or less (facilitation), about 30 seconds (augmentation) and several minutes (post tetanic potentiation). These forms of short term potentiation are usually attributed to a transient elevation in presynaptic calcium ions (Ca2+) concentration following the arrival of the action potential. Otherwise, presynaptic depression processes, as well as the facilitation ones, depend on neurotransmitter release probability. Thus, synapses with high release probability show few facilitation and are easily depressed because of their ability to deplete faster all synaptic vesicles of the ready releasable pool.

CONCLUSIONS

Short term synaptic plasticity appears to serve as a flexible mechanism for temporal information processing in higher cortical integration.

[Clinical and epidemiological characteristics of persons newly diagnosed of HIV infection]

BACKGROUND

We describe the characteristics of people with a recent diagnosis of HIV infection.

PATIENTS AND METHOD

Series of 126 new cases of HIV infection diagnosed in an infectious diseases Service.

RESULTS

Sexual transmission was the commonest form of infection (74%). Fifteen percent of individuals were aged over 50 years and 16% were immigrants. A late diagnosis (stage C) accounted for 36% of cases and it was associated with being more than 50 years old (OR: 5.1; 95% CI: 1.6-16.8).

CONCLUSIONS

It is necessary to implement HIV infection surveillance systems and to improve preventive services.

A fish cell surface receptor defined by a mAb mediates leukocyte aggregation and deactivation

Cell adhesion molecules play a key role in the inflammatory response. Selectins, integrins and immunoglobulin gene superfamily adhesion receptors mediate the different steps of leukocyte migration from the blood-stream towards inflammatory foci. In addition to their adhesive function, these receptors modulate major cellular processes such as cell activation, growth, differentiation and death. To characterise the fish molecules involved in cell adhesion, a panel of mAbs was raised by immunising mice with macrophages from the marine fish gilthead seabream (Sparus aurata L.). One of these mAbs, which we named anti-Aggregatin, was found to induce a rapid heterotypic aggregation of seabream leukocytes. Anti-Aggregatin defined a 140-kDa cell surface receptor which was highly expressed by macrophages and was up-regulated after co-stimulation with LPS and MAF. Functionally, the cell adhesion which occurred upon exposure to anti-Aggregatin required Ca(2+), an intact cytoskeleton and an active cell metabolism. More importantly, Aggregatin engagement resulted in strong inhibition of the phagocyte respiratory burst, although the cells showed neither loss of viability nor DNA fragmentation. The results are discussed in relation to the potential role of cell adhesion molecules in fish immune responses.

Molecular pathology of endometrial hyperplasia and carcinoma

Four different genetic abnormalities may occur in endometrioid adenocarcinomas of the endometrium (mircosatellite instability and mutations in the PTEN, k-RAS and beta-catenin genes), whereas nonendometrioid carcinomas of the endometrium often have p53 mutations and loss of heterozygosity on several chromosomes. Occasionally, a nonendometrioid carcinoma may develop as a result of dedifferentiation of a preexisting endometrioid carcinoma; in such a case, the tumor exhibits overlapping clinical, morphologic, immunohistochemical, and molecular features of the 2 types. The insaturation of microsatellite instability in endometrial carcinogenesis seems to occur late in the transition from complex hyperplasia to carcinoma, and it is preceded by progressive inactivation of MLH-1 by promoter hypermethylation. Moreover, the endometrioid adenocarcinomas that exhibit microsatellite instability show a stepwise progressive accumulation of secondary mutations in oncogenes and tumor suppressor genes that contain short-tandem repeats in their coding sequences. Mutations in the PTEN and k-RAS genes are also frequent in endometrioid adenocarcinomas of the endometrium, particularly in the tumors that exhibit microsatellite instability, whereas beta-catenin mutations do not seem to be associated with such a phenomenon.

Radicular involvement and medullary invasion from a malignant mesothelioma

We present the case of a 57-year-old patient who had worked at a fiber-cement factory for 28 years. The patient developed an epithelioid-type pleural mesothelioma 5 years after retiring, after he was diagnosed with asbestosis. Only 5 months after the diagnosis of mesothelioma, a medullar section appeared to be totally invaded by a tumor in the medullar canal, thus causing paraplegia and affecting the bladder and anal sphincters. The patient underwent radiotherapy and chemotherapy, and achieved partial recovery, but died 9 months after the diagnosis.

Usefulness of route of transmission, absolute CD8+ T-cell counts, and levels of serum tumor necrosis factor alpha as predictors of survival of HIV-1-infected patients with very low CD4 + T-cell counts

Potential cofactors of survival in HIV-1-infected patients with CD4+ T-cell counts of < or = 100 cells/microl were investigated. All 132 patients with CD4+ T-cell counts of < or = 100 cells/microl were selected from 416 patients included in an antiretroviral therapy cohort (1989-1999). Fifty of 54 deaths were due to AIDS. There were significant associations (P<0.05) between survival and CD8+ T-cell counts, clinical AIDS stage, risk group, and antiretroviral drug regimen after baseline, but only the use of protease inhibitors had an independent effect on survival (hazard ratio [HR], 0.096; 95% confidence interval [95%CI], 0.094-0.097). A substudy restricted to the cohort of 108 patients never exposed to PIs detected independent associations between survival and CD8+ T-cell counts (P=0.0016), experience with antiretroviral therapy before baseline (HR, 2.52; 95%CI, 1.31-4.82), sexual risk group for HIV infection (HR, 3.7; 95%CI, 1.92-7.12), and levels of serum tumor necrosis factor alpha (P=0.02). This study confirms that the use of PI-containing antiretroviral regimens strongly predicts survival of HIV-1-infected patients with very low CD4+ T-cell counts. When the study was restricted to patients never exposed to PIs, the parenteral route of disease transmission, high absolute CD8 + T-cell counts, and low serum levels of tumor necrosis factor alpha were independent predictors of survival in extremely advanced HIV-1 disease.

Critical factors in chitin production by fermentation of shrimp biowaste

Factors affecting Lactobacillus fermentation of shrimp waste for chitin and protein liquor production were determined. The objective of the fermentation is medium conditioning by Lactobacillus through production of proteases and lowering of the pH. The efficiency was tested by conducting fermentation of biowaste in 1-1 beakers with or without pH adjustment using different acids. Addition of 5% glucose to the biowaste supported the growth of lactic acid bacteria and led to better fermentation. Among four acids tested to control pH at the start and during fermentation, acetic acid and citric acid proved to be the most effective. In biowaste fermented with 6.7% L. plantarum inoculum, 5% glucose, and pH 6.0 adjusted with acetic acid, 75% deproteination and 86% demineralization was achieved. Replacement of acetic acid by citric acid gave 88% deproteination and 90% demineralization. The fermentation carried out in the presence of acetic acid resulted in a protein fraction that smelled good and a clean chitin fraction.

Mitoxantrone, etoposide, carboplatinum and ara-C combination therapy (MECA) in refractory and relapsed acute leukemia

The present study was undertaken to assess the feasibility, toxicity and antileukemic activity of sequential chemotherapy including mitoxantrone, etoposide, carboplatin and intermediate-dose cytarabine in adult patients with refractory and relapsed acute myelogenous (AML) or lymphoid (ALL) leukemia. Fifty-one patients with poor-risk AML and ALL received 64 courses of MECA therapy. The overall response in the entire group was 51% (43% complete remission). The stage of the disease (relapsed or primarily refractory) and the age of the patients did not strongly affect the response rate. MECA therapy was more effective in ALL than in AML, and in those patients who presented at salvage treatment with a bone marrow infiltration lower than 25% blasts. Hematological and extra-hematological toxicities were tolerable and there were 6 deaths related to the treatment (11%). The incidence of documented infectious episodes was 71%. MECA therapy is a safe treatment and has a high antileukemic activity in relapsed and primarily refractory AML or ALL.

[Molecular genetics of astrocytomas]

Astrocytomas are the most frequent group of intracranial tumors. Among them, glioblastoma is the most aggressive one. In this review we will describe the most common genetic abnormalities found out in astrocytomas. We will refer to the epidermal growth factor receptor (EGFR), p53, p16, PTEN and DMBT1 genes. We will also present certain genetic aspects that influence the progression to glioblastoma.

Aged mice exhibit greater mortality concomitant to increased brain and plasma TNF-alpha levels following intracerebroventricular injection of lipopolysaccharide

BACKGROUND

Age-related defects in the development of peripheral inflammatory responses have been observed in rodents and humans.

OBJECTIVE

We examined the effects of age on a centrally injected endotoxin-induced cytokine production and cellular activation in mice.

METHODS

Male C57BL/6J (B6) mice, C3H/HeN mice, and C3H/HeJ mice received an intracerebroventricular injection of lipopolysaccharide (LPS) and were sacrificed at various times (2, 4, 8 h) thereafter. ELISA for IL-1beta, IL-6, IL-12, and TNF-alpha were conducted on forebrain tissue homogenates as well as plasma samples, and lectin staining to detect activated microglia was prepared for selected brain slices.

RESULTS

Intracerebroventricular injection of LPS in B6 mice produced an age-associated increase in mortality which was paralleled with a significant increase in brain and plasma levels of TNF-alpha. AntiTNF-alpha- and IL-6-immunoreactive cells possessed macrophagelike morphologies and were observed along the LPS injection tract and scattered throughout the hilus of the dorsal hippocampus and cerebral cortices. This LPS-mediated response was found to be specific in that the LPS-hyporesponsive mouse strain (C3H/HeJ) failed to demonstrate significant brain or plasma levels of TNF-alpha after LPS administration compared to C3H/HeN mice.

CONCLUSION

These results suggest that the age-related increases in TNF-alpha production and mortality following the intracerebroventricular administration of LPS may be due to an increased endotoxin hypersensitivity of brain microglia/macrophages within aged animals.

Prolactin (PRL)-PRL receptor system increases cell proliferation involving JNK (c-Jun amino terminal kinase) and AP-1 activation: inhibition by glucocorticoids

PRL receptor (PRLR) signal transduction supports PRL-induced growth/differentiation processes. While PRL is known to activate Jak2-Stat5 (signal transducer and activator of transcription 5) signaling pathway, the mechanism by which cell proliferation is stimulated is less known. We show that PRL induces proliferation of bovine mammary gland epithelial cells and AP-1 site activation. Using PRLR mutants and the PRLR short form, we have found that both homodimerization of PRLR wild type and the integrity of box-1 and C-distal tyrosine of PRLR intracellular domain are needed in PRL-induced proliferation and AP-1 activation. The effect of PRL has been assayed in the presence of dexamethasone (Dex), insulin, and alone. We found that Dex negatively regulates PRL-induced proliferation and AP-1 site activation. We demonstrate that PRL exerts activation of AP-1 transcriptional complex, and the mechanism by which this activation is produced is also studied. We show that PRL induces an increase in the c-Jun content of AP-1 transcriptional complexes. The PRL-induced c-Jun of AP-1 transcriptional complex diminishes in the presence of Dex in a dose-dependent manner. Dex inhibition was reversed by the higher concentration of PRL added to cells. Despite the fact that the regulation of the AP-1 site is complex, we found that PRL activates the c-Jun amino terminal kinase (JNK), while glucocorticoid prevents this JNK activation. These data support a regulation of cellular growth by PRL-PRLR system by increasing AP-1 transcriptional complex activity via JNK activation. JNK activation can be repressed by glucocorticoid in a DNA-binding-independent manner.

[Control of inhaled triggering factors decreases prolonged drug therapy requirements in patients with asthma]

The past decade of research has led to a greater understanding of the pathogenesis of asthma and, in particular, the pivotal role of the underlying inflammatory process. Along with inheritance in atopic patients, the presence of inhaled triggering allergens are considered the predominant predisposing factors in the development of the disease. We have conducted a longitudinal clinical therapeutic study, which included 45 pediatrics patients with asthma, in order to evaluate whether the removal of any potential inhaled triggering factor, could decrease the requirement of drug based anti-inflammatory therapy. Patients admitted in this study presented at least, two monthly asthma attacks during the last four months. A single treatment with theophylline (group A), beclomethasone (group B) or salbutamol (group C), was prescribed during the first 2 weeks, along with specific instructions to avoid inhaled allergens. Regardless of the drug used, patients showed impressive and prolonged clinical improvement during 6 months, reduction of total IgE serum levels in the three groups (p < 0.02; 0.005 and 0.02 respectively) and favorable modification of force expiratory volume at the first second, forced vital capacity and flow expiratory peak. During the observation period a constant monitoring of mites allergens concentrations was performed, showing a decrease of these antigens, associated with clinical improvement, and only in those patients who remained symptomatic (group A 31%, group B 29% and group C 9%), failures performing the measures designed to reduce their exposure to environmental allergens, was demonstrated. These results suggest that reduction of inhaled triggering factors may decrease the requirement of anti-inflammatory drug therapy to control the symptoms in patients with asthma.

Chemical and rheological properties of an extracellular polysaccharide produced by the cyanobacterium Anabaena sp. ATCC 33047

The cyanobacterium (blue-green alga) Anabaena sp. ATCC 33047 produces an exopolysaccharide (EPS) during the stationary growth phase in batch culture. Chemical analysis of EPS revealed a heteropolysaccharidic nature, with xylose, glucose, galactose, and mannose the main neutral sugars found. The infrared (IR) spectrum of EPS showed absorption bands of carboxylate groups. The average molecular mass of the polymer was 1.35 MDa. Aqueous dispersions at EPS concentrations ranging from 0.2% to 0.6% (w/w) showed marked shear-thinning properties (power-law behavior). Linear dynamic viscoelastic properties showed that the elastic component was always higher than the viscous component. Viscous and viscoelastic properties demonstrated the absence of conformational changes within the concentration range studied. Stress-growth experiments revealed that 0.4% and 0.6% (w/w) EPS dispersions showed thixotropic properties. A detailed comparison of the linear dynamic viscoelasticity, transient flow, and decreasing shear rate flow curve properties was made for 0.4% (w/w) dispersions of xanthan gum (XG), Alkemir 110 (AG), and EPS. Viscoelastic spectra demonstrated that the EPS dispersion turned out to be more "fluidlike" than the AG and XG dispersions. The flow indexes indicated that the EPS dispersion was less shear-sensitive than that of XG, showing essentially the same viscosity, that is, >50 s(-1). The fact that viscosities of EPS and AG dispersions were not substantially different within the shear-rate range covered must be emphasized, in relation to EPS potential applications. The rheological behavior of EPS dispersions indicates the formation of an intermediate structure between a random-coil polysaccharide and a weak gel.

Prognostic value of the expression of E-cadherin and beta-catenin in bladder cancer

The purpose of this study was to assess the prognostic effect of the expression of E-cadherin, beta-catenin and CD44 adhesion molecules in bladder carcinoma. 22 superficial and 18 invasive bladder tumour samples were studied by immunohistochemistry. The median follow-up was 24 months (range: 1-50 months). Loss of E-cadherin and beta-catenin immunoreactivity was found in 14 (35%) and 17 (43%) tumours, respectively, and was significantly associated with invasiveness, high grade and p53 overexpression. There was no correlation between CD44 variant expression and clinicopathological findings. Loss of E-cadherin expression was an independent predictor of poor survival in a multivariate analysis, when assessed with age, grade, stage and p53 status (hazards ratio adjusted (HRa)=4.45 [95% confidence interval (CI), 1.06-18.63]). This effect was particularly augmented in patients with invasive bladder cancer. When expression of E-cadherin and beta-catenin were evaluated simultaneously, loss of immunoreactivity of both proteins was a strong predictor of poor survival (HRa=13.06 [95% CI, 0.95-178.55]). The same pattern was found when progression-free survival in relation to these variables was assessed. In conclusion, assessment of E-cadherin and beta-catenin immunoreactivity may be a useful prognostic marker in bladder cancer complementary to established prognostic factors.