Myocardial extra-cellular matrix and its regulation by metalloproteinases and their inhibitors

Cardiovascular disease poses a major health care burden in the Western world. Following myocardial injuries, ventricular remodelling and dysfunction ensue, which can eventually culminate in heart failure. An important event in left ventricular (LV) remodelling is alteration of the extracellular matrix (ECM) integrity, the structural network that interconnects the myocardial components. The critical role of ECM remodelling in cardiac dilation and heart failure was recognized more than a decade ago, and the molecular factors responsible for this process are now being explored. Abnormal ECM turnover is primarily brought about by an imbalance in the activity of matrix metalloproteinases (MMPs) that degrade ECM components, and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs). Here we provide an overview of composition of the cardiac ECM, and alterations in ECM regulatory proteins, MMPs and TIMPs, in human heart disease. We also discuss the role of TIMPs, MMPs, and a disintegrin and metalloproteinase (ADAMs) enzymes in cardiac development and function as learned through genetically altered mouse models.     

Residual symptoms in older patients treated for major depression

OBJECTIVE: The purpose of this study was to identify residual symptoms in a sample of older adults treated for major depression and compare individual symptoms present at baseline with those at three months by remission status. METHODS: The sample was comprised of 229 patients with DSM-IV major depression who were participants in the NIMH Mental Health Clinical Research Center at Duke University. Symptoms were measured using the Montgomery-Asberg Depression Rating Scale (MADRS). RESULTS: At three months, 86 patients (37.6%) had remitted, or had a MADRS score less than or equal to 9. In the remitted group, the most frequently reported symptoms at three months were inner tension and lassitude. Among nonremitters, the most frequently reported symptoms were reported and apparent sadness, as well as lassitude and inner tension. In the sample as a whole, the symptoms most likely to be present at baseline but not three months were pessimistic and suicidal thoughts, while the most frequently reported emergent symptoms were reduced appetite and inner tension. Patients were much more likely to no longer have a particular symptom than to acquire a new symptom. Overall, the symptoms present at three months were not severe in either group. CONCLUSIONS: In older adults treated for major depression, residual symptoms at three months may include emergent symptoms as well as persistent symptoms, and are likely to include symptoms of anxiety as well as sadness. These findings have clinical implications for the treatment of late-life depression.     

Supracondylar Femoral Nail in the management of non-union of humeral shaft fractures

We reviewed seven patients with established non-union of a shaft of humerus fracture, treated by locked intramedullary nailing using the Intramedullary Supracondylar Nail (IMSC Nail; Smith & Nephew Richards, Memphis TN). The mean age of the patients was 65 years (range 48-78 years). Three of the fractures involved the proximal third of the diaphysis while the remaining four involved the middle third. Six of the original fractures were closed and one was an open fracture. The time interval between the original injury and final surgery averaged 9.3 months. All the nailings were done by the ante-grade approach with static locking. Six of the patients had closed nailing and one had open nailing with bone grafting. The mean follow-up was 8 months and osseous union was achieved in all seven cases at a mean of 5.6 months. We conclude that the Supracondylar Femoral Nail is a useful alternative implant in the management of non-union of fractures of the humeral shaft with wide medullary canals.     

Molecular cloning, expression and characterization of a serine proteinase inhibitor gene from Entamoeba histolytica

Serine proteinase inhibitors (serpins) are irreversible suicide inhibitors of proteinases that regulate a wide range of biological processes, including pathogen evasion of the host defence system. We report the cloning and characterization of a gene encoding a serpin from the protozoan parasite Entamoeba histolytica (Ehserp) that may function in this manner. The protein encoded by Ehserp contains 371 amino acids with a predicted mass of 42.6 kDa. Antibodies to a 42 kDa recombinant Ehserp react specifically with two bands of 42 and 49 kDa in trophozoite extracts. Ehserp has a cytoplasmic localization and is secreted by trophozoites incubated in the presence of mammalian cells, but not by resting trophozoites. A panel of mammalian serine proteinases was screened, but none of them was inhibited by the recombinant Ehserp. In contrast, the 49 kDa Ehserp present in the secretion product (SP) of activated macrophages interacted with human neutrophil cathepsin G to form a complex resistant to sodium dodecyl sulphate. We discuss the nature of the 42 and 49 kDa Ehserp and the possible roles that Ehserp may play in the survival of the parasite inside the host.     

Formulation of an HPMC gel drug reservoir system with ethanol-water as a solvent system and limonene as a penetration enhancer for enhancing in vitro transdermal delivery of nicorandil

The objective of the present study was to formulate a hydroxypropyl methylcellulose (HPMC) gel drug reservoir system with ethanol-water as a solvent system and limonene as a penetration enhancer for enhancing the transdermal delivery of nicorandil so as to develop and fabricate a membrane-moderated transdermal therapeutic system (TTS). The in vitro permeation of nicorandil was determined across rat abdominal skin from a solvent system consisting of ethanol or various proportions of ethanol and water. The ethanol-water (70:30 v/v) solvent system that provided an optimal transdermal permeation was used in formulating an HPMC gel drug reservoir system with selected concentrations (0% w/w, 4% w/w, 6% w/w, 8% w/w or 10% w/w) of limonene as a penetration enhancer for further enhancement of transdermal permeation of nicorandil. The amount of nicorandil permeated in 24 h was found increased with an increase in the concentration of limonene in the drug reservoir system up to a concentration of 6% w/w, but beyond this concentration there was no further increase in the amount of drug permeated. The flux of nicorandil was 370.9 +/- 4.2 microg/cm2 x h from the drug reservoir system with 6% w/w of limonene, which is about 2.6 times the required flux to be obtained across rat abdominal skin for producing the desired plasma concentration for the predetermined period in humans. The results of a Fourier Transform Infrared study indicated that limonene enhanced the percutaneous permeation of nicorandil by partially extracting the stratum corneum lipids. It is concluded that the HPMC gel drug reservoir system prepared with a 70:30 v/v ethanol-water solvent system containing 6% w/w of limonene is useful in designing and fabricating a membrane-moderated TTS of nicorandil.     

Inactivation of the cytotoxic activity of repin, a sesquiterpene lactone from Centaurea repens

Prolonged ingestion of Yellow Starthistle (Centaurea solstitialis) and Russian Knapweed (Centaurea repens) by horses has been shown to result in a fatal neurodegenerative disorder called equine nigropallidal encephalomalacia (ENE). Bioassay-guided fractionation of extracts from Centaurea species using the PC12 cell line have led to the identification of one of several putative agents, which may contribute to ENE, namely, the sesquiterpene lactone (SQL) repin (1), previously linked to ENE due to its abundance in C. repens. To characterize the molecular basis of repin-induced neurotoxicity, the present study was designed to identify reactive functional groups that may contribute overall to its toxicity. The reaction of repin (1) with glutathione (GSH) led to the exclusive addition of GSH to the alpha-methylenebutyrolactone affording a GSH conjugate (3b) that lacked toxicity in the PC12 cell assay, while selective reduction of the alpha-methylenebutyrolactone double bond of 1 also resulted in an analogue (2) that was devoid of toxicity relative to the parent compound. Unlike repin, analogue 2 failed to decrease cellular dopamine levels in PC12 cells, further substantiating the requirement of the alpha-methylenebutyrolactone group. Results from this study are suggestive that GSH depletion by the SQL repin may be a primary event in the etiology of ENE, increasing the susceptibility to oxidative damage.     

Amphotericin B molecular organization as an essential factor to improve activity/toxicity ratio in the treatment of visceral leishmaniasis

An in vivo study has been performed in order to determine the influence of amphotericin B (AMB) molecular organization on the toxicity and activity of this drug in the treatment of experimental visceral leishmaniasis. Three formulations with similar composition but different drug molecular self-association in aqueous media were prepared. Acute toxicity was evaluated by injecting them in healthy hamsters. Sub-acute toxicity and efficacy were studied administering them to animals previously infected with Leishmania infantum. The preparation with drug molecules completely dissolved into monomers (formulation "C") and produced the highest acute toxicity. The formulation whose AMB molecules were disposed as non-water-soluble multi-aggregates (formulation "B") proved to provide the lowest acute toxicity. This formula also showed an improved activity, mainly in the liver, if compared with the third tested formulation containing AMB molecules disposed as smaller dimerical "water-soluble" aggregates (formulation "A"). As a conclusion, molecular aggregation in biological media should be an important factor to consider when researching or optimizing medicines containing AMB. The liberation of molecules as large dispersed non-water-soluble multi-aggregates seems to improve the narrow therapeutic margin attached to the use of this drug.