High-Throughput Generation of P. falciparum Functional Molecules by Recombinational Cloning

Large-scale functional genomics studies for malaria vaccine and drug development will depend on the generation of molecular tools to study protein expression. We examined the feasibility of a high-throughput cloning approach using the Gateway system to create a large set of expression clones encoding Plasmodium falciparum single-exon genes. Master clones and their ORFs were transferred en masse to multiple expression vectors. Target genes (n = 303) were selected using specific sets of criteria, including stage expression and secondary structure. Upon screening four colonies per capture reaction, we achieved 84% cloning efficiency. The genes were subcloned in parallel into three expression vectors: a DNA vaccine vector and two protein expression vectors. These transfers yielded a 100% success rate without any observed recombination based on single colony screening. The functional expression of 95 genes was evaluated in mice with DNA vaccine constructs to generate antibody against various stages of the parasite. From these, 19 induced antibody titers against the erythrocytic stages and three against sporozoite stages. We have overcome the potential limitation of producing large P. falciparum clone sets in multiple expression vectors. This approach represents a powerful technique for the production of molecular reagents for genome-wide functional analysis of the P. falciparum genome and will provide for a resource for the malaria resource community distributed through public repositories.     

Oncocytic adencarcinoma of the rectum with diffuse intra-luminal microcalcifications: the first reported case

Several histological variants of colorectal carcinoma have been reported, some of them bearing prognostic significance, others only incidental findings showing unusual morphological features. The current report was aimed to describe the histological, immunohistochemical and ultrastructural features of an oncocytic adenocarcinoma of the rectum occurring in a 66-year-old woman. Histologically, it was a moderately differentiated adenocarcinoma composed by glandular structures lined by eosinophilic cells. The latter showed abundant granular cytoplasm and large nuclei with prominent nucleoli. Several glandular structures contained intraluminal, basophilic and non-birifrangent microcalcifications. The tumour cells displayed consistent anti-mitochondrial antigen, carcinoembryonic antigen, p53, CDX2 and cytokeratin 20 immunoreactivity. Ultrastructurally, more than 80% of the cytoplasmic area was occupied by abnormal mitochondria, while exocrine or endocrine granules were undetectable. The tumour infiltrated the intestinal wall through the subserosal tissue, but lymph node or distant metastases were absent. The patient is disease free 22 months after surgery. Based on the above features, this case could be appropriately named oncocytic adenocarcinoma with intraluminal microcalcifications. Like gastric neoplasms showing similar morphologic features, this tumour might have a better prognosis, and the presence of microcalcifcations could help its proper recognition at a pre-operative stage.     

Age and sex influence on oxidative damage and functional status in human skeletal muscle

A reduction in muscle mass, with consequent decrease in strength and resistance, is commonly observed with advancing age. In this study we measured markers of oxidative damage to DNA, lipids and proteins, some antioxidant enzyme activities as well Ca²⁺ transport in sarcoplasmic reticulum membranes in muscle biopsies from vastus lateralis of young and elderly healthy subjects of both sexes in order to evaluate the presence of age- and sex- related differences. We found a significant increase in oxidation of DNA and lipids in the elderly group, more evident in males, and a reduction in catalase and glutathione transferase activities. The experiments on Ca²⁺ transport showed an abnormal functional response of aged muscle after exposure to caffeine, which increases the opening of Ca²⁺ channels, as well a reduced activity of the Ca²⁺ pump in elderly males. From these results we conclude that oxidative stress play an important role in muscle aging and that oxidative damage is much more evident in elderly males, suggesting a gender difference maybe related to hormonal factors.This revised version was published online in September 2005 with corrections to the Cover Date.     

Transcranial magnetic stimulation of the occipital pole interferes with verbal processing in blind subjects

Recent neuroimaging studies in blind persons show that the occipital cortex, including the primary visual cortex (V1), is active during language-related and verbal-memory tasks. No studies, however, have identified a causal link between early visual cortex activity and successful performance on such tasks. We show here that repetitive transcranial magnetic stimulation (rTMS) of the occipital pole reduces accuracy on a verb-generation task in blind subjects, but not in sighted controls. An analysis of error types revealed that the most common error produced by rTMS was semantic; phonological errors and interference with motor execution or articulation were rare. Thus, in blind persons, a transient 'virtual lesion' of the left occipital cortex interferes with high-level verbal processing     

Mast cell tryptase may modulate endothelial cell phenotype in healing myocardial infarcts

Mast cells and macrophages infiltrate healing myocardial infarcts and may play an important role in regulating fibrous tissue deposition and extracellular matrix remodelling. This study examined the time-course of macrophage and mast cell accumulation in healing infarcts and studied the histological characteristics and protease expression profile of mast cells in a canine model of experimental infarction. Although macrophages were more numerous than mast cells in infarct granulation tissue, macrophage density decreased during maturation of the scar, whereas mast cell numbers remained persistently elevated. During the inflammatory phase of infarction, newly recruited leucocytes infiltrated the injured myocardium and appeared to be clustered in close proximity to degranulating cardiac mast cells. During the proliferative phase of healing, mast cells had decreased granular content and were localized close to infarct neovessels. In contrast, macrophages showed no selective localization. Mast cells in healing canine infarcts were alcian blue/safranin-positive cells that expressed both tryptase and chymase. In order to explain the pro-inflammatory and angiogenic actions of tryptase--the major secretory protein of mast cells--its effects on endothelial chemokine expression were examined. Chemokines are chemotactic cytokines that play an important role in leucocyte trafficking and angiogenesis and are highly induced in infarcts. Tryptase, a proteinase-activated receptor (PAR)-2 agonist, induced endothelial expression of the angiogenic chemokines CCL2/MCP-1 and CXCL8/IL-8, but not the angiostatic chemokine CXCL10/IP-10. Endothelial PAR-2 stimulation with the agonist peptide SLIGKV induced a similar chemokine expression profile. Mast cell tryptase may exert its angiogenic effects in part through selective stimulation of angiogenic chemokines.     

Effects of thyroid hormones on the biochemical specialization of human muscle fibers

The effects of thyrotoxicosis and of hypothyroidism on human muscle have been studied on single fiber preparations. In thyrotoxic muscle, the ratio between fibers showing the fast type of myofibrillar protein isoforms (fast fibers) and fibers showing the slow type (slow fibers) is increased, as is the percentage of fibers with incomplete segregation of fast and slow myosin (intermediate fibers). Furthermore, in fast fibers, the volume and, to a greater extent, the rate of Ca transport of sarcoplasmic reticulum (SR) are increased, without changes in the affinity for Ca2+ of the Ca-pump or in its sensitivity to the cyclic adenosine monophosphate (cAMP) dependent protein kinase system. These effects are completely reversed by the removal of thyroid hormones, as demonstrated by hypothyroid muscles. It is suggested that in human muscle cells thyroid hormones are critical for the expression of fast genes and for SR Ca transport.