Repeat regions of malaria parasite proteins: a review of structure and possible role in the biology of the parasite.

Tandemly repeated amino acid sequences are characteristic of many malaria parasite proteins that have been sequenced to date. Strong selective pressures must exist to maintain the repeat regions and also to diversify them in the case proteins containing strain-variant repeats. Repeats have been suggested to function in immune-evasion and in binding to host receptors. This article focuses on the structural characteristics of the repeats in relation to their postulated function.     

Nuclear magnetic resonance studies of lithium transport in erythrocyte suspensions of hypertensives

We have applied a nuclear magnetic resonance (NMR) method, based on the 7Li nucleus, to discriminate between intracellular and extracellular lithium ions (Li+) in red blood cell (RBC) suspensions. The NMR method was compared with atomic absorption, a technique that requires physical separation of intra- and extracellular Li+ prior to chemical analysis. The rates and rate constants of RBC Na(+)-Li+ countertransport measured by the 7Li NMR method correlated significantly with the measurements made by atomic absorption for both the hypertensive (r = 0.964) and control (r = 0.961) groups. The rates of RBC Na(+)-Li+ countertransport measured by NMR were significantly higher for hypertensive patients than for normotensive controls. The fact that the NMR method does not require cell membrane lysis, and its potential to reveal structural and mechanistic information on Li+ binding and transport in cellular systems, makes it promising for understanding the basis of Li+ transport variations in RBCs, and possibly other tissues, from hypertensive patients.     

Reactive oxygen species produced by macrophage-derived foam cells regulate the activity of vascular matrix metalloproteinases in vitro. Implications for atherosclerotic plaque stability.

Vulnerable areas of atherosclerotic plaques often contain lipid-laden macrophages and display matrix metalloproteinase activity. We hypothesized that reactive oxygen species released by macrophage-derived foam cells could trigger activation of latent proforms of metalloproteinases in the vascular interstitium. We showed that in vivo generated macrophage foam cells produce superoxide, nitric oxide, and hydrogen peroxide after isolation from hypercholesterolemic rabbits. Effects of these reactive oxygens and that of peroxynitrite, likely to result from simultaneous production of nitric oxide and superoxide, were tested in vitro using metalloproteinases secreted by cultured human vascular smooth muscle cells. Enzymes in culture media or affinity-purified (pro-MMP-2 and MMP-9) were examined by SDS-PAGE zymography, Western blotting, and enzymatic assays. Under the conditions used, incubation with xanthine/xanthine oxidase increased the amount of active gelatinases, while nitric oxide donors had no noticeable effect. Incubation with peroxynitrite resulted in nitration of MMP-2 and endowed it with collagenolytic activity. Hydrogen peroxide treatment showed a catalase-reversible biphasic effect (gelatinase activation at concentrations of 4 microM, inhibition at > or = 10-50 microM). Thus, reactive oxygen species can modulate matrix degradation in areas of high oxidant stress and could therefore contribute to instability of atherosclerotic plaques.     

Intraoperative portal vein blood flow predicts allograft and patient survival following liver transplantation

Background:

We hypothesized that operative variables might predict survival following liver transplantation.

Methods:

We examined perioperative variables from 469 liver transplants carried out at the University of Washington during 2003–2006. Logistic regression determined the variables'' contributions to survival at 30, 90 and 365 days.

Results:

Portal vein blood flow (>1 l/min) was significant to patient survival at 30, 90 and 365 days. Complete reperfusion was only a significant predictor of survival at 30 days. This provided model receiver operating characteristic (ROC) area under the curve (AUC) statistics of 0.93 and 0.87 for 30 and 90 days, respectively. At 365 days, hepatic artery blood flow (>250 ml/min) combined with portal vein blood flow was significantly predictive of survival, with an AUC of 0.74. A subset analysis of 110 transplants demonstrated improved 1-year survival with more aggressive vascular revisions.

Discussion:

Portal vein blood flow is a significant predictor of survival after liver transplantation. Initially, the liver''s survival is based on portal vein blood flow; however, subsequent biliary problems and patient demise result from both poor portal vein and inadequate hepatic artery blood flow.     

In vitro antiplasmodial activity of ethanolic extracts of seaweed macroalgae against <Emphasis Type="Italic">Plasmodium falciparum</Emphasis>

Malaria is a major health problem in many developing countries. The drugs resistant Plasmodium falciparum causes the most virulent form of malaria in humans and it is described as a public health disaster causing increased morbidity and mortality. Thirteen seaweeds species which belong to four different families (Rhodomelaceae, Cladophoraceae, Ulvaceae, and Caulerpaceae) were collected from Mandapam coastal area and the seaweeds extracts were tested for in vitro antiplasmodial activity against P. falciparum. Among them, Caulerpa toxifolia (IC₅₀ 5.06 μg·ml⁻¹) showed potential antiplasmodial activity than other seaweeds extracts and it can be comparable with the positive control artemether (IC₅₀ 4.09 μg·ml⁻¹). Caulerpa peltata (IC₅₀ 16.69 μg·ml⁻¹) also exhibited good antiplasmodial activity and the IC₅₀ value is lesser than the positive control chloroquine (IC₅₀ 19.59 μg·ml⁻¹). Statistical analysis reveals that significant in vitro antiplasmodial activity (P < 0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out and it shows that no morphological changes in erythrocytes by the ethanolic extract of seaweeds extracts after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of sugars, proteins, and phenols in the ethanolic extracts of seaweeds. It is concluded from the present study that, the ethanolic extracts of seaweeds of C. toxifolia and C. peltata possesses lead compounds for development of antiplasmodial drugs.     

Penetrating Missile Injuries During the Iraqi Insurgency

INTRODUCTION

Since the invasion of Iraq in 2003, the conflict has evolved from asymmetric warfare to a counter-insurgency operation. This study investigates the pattern of wounding and types of injuries seen in casualties of hostile action presenting to a British military field hospital during the present conflict.

PATIENTS AND METHODS

Data were prospectively collected on 100 consecutive patients either injured or killed from hostile action from January 2006 who presented to the sole coalition field hospital in southern Iraq.

RESULTS

Eighty-two casualties presented with penetrating missile injuries from hostile action. Three subsequently died of wounds (3.7%). Forty-six (56.1%) casualties had their initial surgery performed by British military surgeons. Twenty casualties (24.4%) sustained gunshot wounds, 62 (75.6%) suffered injuries from fragmentation weapons. These 82 casualties were injured in 55 incidents (mean, 1.49 casualties; range 1–6 casualties) and sustained a total 236 wounds (mean, 2.88 wounds) affecting a mean 2.4 body regions per patient. Improvised explosive devices were responsible for a mean 2.31 casualties (range, 1–4 casualties) per incident.

CONCLUSIONS

The current insurgency in Iraq illustrates the likely evolution of modern, low-intensity, urban conflict. Improvised explosive devices employed against both military and civilian targets have become a major cause of injury. With the current global threat from terrorist bombings, both military and civilian surgeons should be aware of the spectrum and emergent management of the injuries caused by these weapons.