Activities of alkoxyalkyl esters of cidofovir (CDV), cyclic CDV, and (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine against orthopoxviruses in cell monolayers and in organotypic cultures

The potencies of several alkoxyalkyl esters of acyclic nucleoside phosphonates against vaccinia virus and cowpox virus were evaluated in cell monolayers and three-dimensional epithelial raft cultures. Prodrugs were at least 20-fold more active than their parent compounds. Octadecycloxyethyl-(S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine emerged as the most potent derivative.     

Sympathectomy-like effects of brachial plexus block in arteriovenous access surgery

We used color Doppler ultrasonography to prospectively study the effects of supraclavicular brachial plexus block (BPB) on blood flow and vein diameter in patients undergoing arteriovenous access surgery. BPB might produce a sympathectomy-like effect that could have a role in improving patencty. Thirty-one consecutive patients who underwent arteriovenous access surgery with BPB were studied prospectively, in addition to 5 patients with BPB having other operations and 5 patients undergoing general anesthesia for elective surgery. Vessel diameter and pulsatility index (PI) were among the parameters measured. Mean PI decreased from 6.18 +/- 1.67 before the block to 3.92 +/- 1.75 at 10 min after initiation of the block (p = 0.001). Basilic vein diameter increased from 6.28 +/- 0.86 mm (range 4.85 to 7.30) before the block to 7.83 +/- 1.52 mm (range 5.80 to 12.14) 10 min after the block (p = 0.03). In the general anesthesia control group the PI decreased, but returned to preanesthetic levels immediately after the patients reached the recovery room. In the nonaccess BPB group the PI remained low after the block for at least 5 h. Brachial plexus block causes significant venous dilation and a significant decrease in the pulsatility index. This appears to be due to a beneficial sympathectomy-like effect of the block that might prevent early failure and improve patency in vascular access surgery.     

A haplotype framework for cystic fibrosis mutations in Iran

This is the first comprehensive profile of cystic fibrosis transmembrane conductance regulator (CFTR) mutations and their corresponding haplotypes in the Iranian population. All of the 27 CFTR exons of 60 unrelated Iranian CF patients were sequenced to identify disease-causing mutations. Eleven core haplotypes of CFTR were identified by genotyping six high-frequency simple nucleotide polymorphisms. The carrier frequency of 2.5 in 100 (1 in 40) was estimated from the frequency of heterozygous patients and suggests that contrary to popular belief, cystic fibrosis may be a common, under-diagnosed disease in Iran. A heterogeneous mutation spectrum was observed at the CFTR locus in 60 cystic fibrosis (CF) patients from Iran. Twenty putative disease-causing mutations were identified on 64 (53%) of the 120 chromosomes. The five most common Iranian mutations together represented 37% of the expected mutated alleles. The most frequent mutation, DeltaF508 (p.F508del), represented only 16% of the expected mutated alleles. The next most frequent mutations were c.1677del2 (p.515fs) at 7.5%, c.4041C>G (p.N1303K) at 5.6%, c.2183AA>G (p.684fs) at 5%, and c.3661A>T (p.K1177X) at 2.5%. Three of the five most frequent Iranian mutations are not included in a commonly used panel of CF mutations, underscoring the importance of identifying geographic-specific mutations in this population.     

Enhanced transduction of malignant glioma with a double targeted Ad5/3-RGD fiber-modified adenovirus

Malignant brain tumors remain refractory to adenovirus type 5 (Ad5)-based gene therapy, mostly due to the lack of the primary Ad5 receptor, the coxsackie and adenovirus receptor, on brain tumor cells. To bypass the dependence on coxsackie and adenovirus receptor for adenoviral entry and infectivity, we used a novel, double targeted Ad5 backbone-based vector carrying a chimeric Ad5/3 fiber with integrin-binding RGD motif incorporated in its Ad3 knob domain. We then tested the new virus in vitro and in vivo in the setting of malignant glioma. Ad5/3-RGD showed a 10-fold increase in gene expression in passaged cell lines and up to 75-fold increase in primary tumors obtained from patients relative to the control. These results were further corroborated in our in vivo human glioma xenograft model, where the Ad5/3-RGD vector showed a 1,000-fold increase in infectivity as compared with the control. Taken together, our findings indicate that Ad5/3-RGD may be a superior vector for applications in glioma gene therapy and therefore warrants further attention in the field of neuro-oncology.     

Plasmodium falciparum ensures its amino acid supply with multiple acquisition pathways and redundant proteolytic enzyme systems

Degradation of host hemoglobin by the human malaria parasite Plasmodium falciparum is a massive metabolic process. What role this degradation plays and whether it is essential for parasite survival have not been established, nor have the roles of the various degradative enzymes been clearly defined. We report that P. falciparum can grow in medium containing a single amino acid (isoleucine, the only amino acid missing from human hemoglobin). In this medium, growth of hemoglobin-degrading enzyme gene knockout lines (missing falcipain-2 and plasmepsins alone or in combination) is impaired. Blockade of plasmepsins with the potent inhibitor pepstatin A has a minimal effect on WT parasite growth but kills falcipain-2 knockout parasites at low concentrations and is even more potent on falcipain-2, plasmepsin I and IV triple knockout parasites. We conclude that: (i) hemoglobin degradation is necessary for parasite survival; (ii) hemoglobin degradation is sufficient to supply most of the parasite's amino acid requirements; (iii) external amino acid acquisition and hemoglobin digestion are partially redundant nutrient pathways; (iv) hemoglobin degradation uses dual protease families with overlapping function; and (v) hemoglobin-degrading plasmepsins are not promising drug targets.     

Unequal representation of cardinal vs. oblique orientations in the middle temporal visual area

A possible neurobiological basis for the "oblique effect" is linked to the finding that more neural machinery is devoted to processing cardinal vs. oblique orientations in primary visual cortex (V1). We used optical imaging to determine whether more territory is devoted to processing horizontal and vertical orientations than oblique orientations in owl monkey middle temporal visual area (MT), a visual area highly sensitive to moving stimuli. We found that more of MT was devoted to representing cardinal than oblique orientations, and that the anisotropy was more prominent in parts of MT representing central vision (< or =10 degrees). Neural responses to orientations of 0 degrees and 90 degrees were also greater than those to 45 degrees and 135 degrees . In comparison, an overrepresentation of cardinal orientations in the representation of central vision in owl monkey V1 was relatively small and inconsistent. Our data could explain the greater sensitivity to motion discrimination when stimuli are moved along cardinal meridians and suggest that the neural machinery necessary to explain the motion oblique effect either originates in MT or is enhanced at this level.     

Cross-priming of T cells to intracranial tumor antigens elicits an immune response that fails in the effector phase but can be augmented with local immunotherapy

Central nervous system (CNS) tumors are thought to be poorly immunogenic. However, whether defective anti-tumor immunity is a consequence of a relative failure of T cell priming versus a deficient effector phase of the anti-tumor immune response is not clear. We utilized a well-defined model system of B16 melanoma expressing the model antigen SIY-GFP to evaluate tumor antigen cross-priming and tumor rejection from the CNS versus subcutaneous compartments. We observed that B16-SIY cells implanted in the CNS were capable of inducing T cell priming as measured by IFN-gamma ELISPOT in the spleen. Cross-priming occurred in the absence of detectable systemic dissemination of the tumor. Despite the induction of a T cell response, CNS tumors grew progressively and were fatal, whereas the same tumor implanted in the flank was rejected. To study the effector phase of the immune response in more detail, in vitro primed 2C/RAG2-/- TCR transgenic CD8+ cells, which recognize the SIY peptide, were adoptively transferred. In addition, the CNS microenvironment was modulated by intracranial delivery of IL-2. While mice that received primed 2C cells alone showed an increase in survival, co-administration of intracranial IL-2 led to a marked prolongation of survival, with 20% of mice surviving at least 120 days. Our results demonstrate that CD8+ T cell cross-priming does indeed occur in response to a CNS tumor, but that manipulation of the brain tumor microenvironment may be necessary to support the effector phase of the anti-tumor immune response.     

The significance of the nitric oxide in electro-convulsive therapy: a proposed neurophysiological mechanism

Electroconvulsive therapy (ECT) is used to treat patients with major depressive disorder, manic episodes and other serious mental disorders. Virtually every neurotransmitter system is affected in ECT. The significance of the nitric oxide (NO), which has an established role as a neurotransmitter, neuromodulator, and an intraneuronal second messenger, in ECT is still not clear. We described the involvement of NO in long-term potentiation, the N-methyl-D-aspartic acid (NMDA) receptor activity, regulation of cerebral blood flow, and the hypothalamic-pituitary axis and propose that this involvement is critical in ECT's efficiency, treatment refractoriness, and neuropsychological sequelae by its influences on these systems. Nitric oxide's significant role in other pathophysiological mechanisms has led to current therapeutic protocols and may be applicable in this setting.