Azadirachtin disrupts formation of organised microtubule arrays during microgametogenesis of Plasmodium berghei

Transmission of malaria parasites from vertebrate blood to the mosquito vector depends critically on the differentiation of the gametocytes into gametes. This occurs in response to environmental stimuli encountered by the parasite in the mosquito bloodmeal. Male gametogenesis involves three rounds of DNA replication and endomitosis, and the assembly de novo of 8 motile axonemes. Azadirachtin, a plant limnoid and insecticide with an unkown mode of action, specifically inhibits the release of motile gametes from activated microgametocytes but does not inhibit growth and replication of a sexual blood stages. We have combined confocal laser scanning microscopy and transmission electron microscopy to examine the effect of azadirachtin on the complex reorganisation of the microtubule cytoskeleton during gametogenesis in Plasmodium berghei. Neither the replication of the genome nor the ability of tubulin monomers to assemble into microtubules upon gametocyte activation were prevented by azadirachtin. However, the drug interfered with the formation of mitotic spindles and with the assembly of microtubules into typical axonemes. Our observations suggest that azadarachtin specifically disrupts the patterning of microtubules into more complex structures, such as mitotic spindles and axonemes.     

Satisfaction with breast reconstruction in women with bilateral prophylactic mastectomy: a descriptive study

Prophylactic bilateral mastectomy is an option for women who are at an increased risk of developing breast cancer. Prophylactic mastectomy is often performed with immediate reconstruction (i.e., at the same time and under the same anesthetic as the mastectomy). Satisfaction with reconstruction has been described previously for women with mastectomy for breast cancer. However, the authors know of no previous research that has reported on satisfaction with reconstruction in patients who have electively sought mastectomy for the prevention of breast cancer. Women in the province of Ontario who had undergone prophylactic bilateral mastectomy plus breast reconstruction between 1991 and 2000 were asked to rate their level of satisfaction with the cosmetic results of their mastectomy and reconstruction and their overall satisfaction with their decision to have prophylactic mastectomy. Women were also asked whether they experienced complications associated with their surgery and what types of complications they experienced. Thirty-seven women completed questionnaires for this study, and all of them had immediate breast reconstruction after prophylactic mastectomy. The majority of women (70.3 percent) reported being satisfied or extremely satisfied with the cosmetic results of their breast reconstruction. Women with self-reported postsurgical complications (16.2 percent) were significantly less satisfied with reconstruction than those who did not report complications (p = 0.009). Personal subjective risk of breast cancer before prophylactic mastectomy was negatively correlated with satisfaction with reconstruction (r = -0.38, p = 0.024) and with subjective risk estimation after prophylactic surgery (r = -0.54, p = 0.001). Women who did not worry about developing breast cancer after prophylactic mastectomy had significantly higher levels of satisfaction with breast reconstruction than those who continued to worry (p < 0.001). Women who reported an improved body image after reconstruction were significantly more likely to report higher levels of satisfaction than those who reported a diminished body image (p = 0.007). The majority of women were satisfied with the cosmetic results of breast reconstruction after prophylactic mastectomy. Women who overestimated their breast cancer risk had lower satisfaction levels. Correcting overestimation of breast cancer risk in women who have prophylactic mastectomy may improve satisfaction with reconstruction following prophylactic mastectomy.     

Psoriasis patients are enriched for genetic variants that protect against HIV-1 disease

An important paradigm in evolutionary genetics is that of a delicate balance between genetic variants that favorably boost host control of infection but which may unfavorably increase susceptibility to autoimmune disease. Here, we investigated whether patients with psoriasis, a common immune-mediated disease of the skin, are enriched for genetic variants that limit the ability of HIV-1 virus to replicate after infection. We analyzed the HLA class I and class II alleles of 1,727 Caucasian psoriasis cases and 3,581 controls and found that psoriasis patients are significantly more likely than controls to have gene variants that are protective against HIV-1 disease. This includes several HLA class I alleles associated with HIV-1 control; amino acid residues at HLA-B positions 67, 70, and 97 that mediate HIV-1 peptide binding; and the deletion polymorphism rs67384697 associated with high surface expression of HLA-C. We also found that the compound genotype KIR3DS1 plus HLA-B Bw4-80I, which respectively encode a natural killer cell activating receptor and its putative ligand, significantly increased psoriasis susceptibility. This compound genotype has also been associated with delay of progression to AIDS. Together, our results suggest that genetic variants that contribute to anti-viral immunity may predispose to the development of psoriasis.     

Epsilon substituted lysinol derivatives as HIV-1 protease inhibitors

A series of HIV-1 protease inhibitors containing an epsilon substituted lysinol backbone was synthesized. Two novel synthetic routes using N-boc-l-glutamic acid alpha-benzyl ester and 2,6-diaminopimelic acid were developed. Incorporation of this epsilon substituent enabled access to the S2 pocket of the enzyme, affording high potency inhibitors. Modeling studies and synthetic efforts suggest the potency increase is due to both conformational bias and van der Waals interactions with the S2 pocket.     

Comparative effects of sodium pyrithione evoked intracellular calcium elevation in rodent and primate ventral horn motor neurons

Oral administration of sodium pyrithione (NaP) causes hindlimb weakness in rodents, but not in primates. Previous work using Aplysia neurons has demonstrated that NaP produces a persistent influx of Ca²⁺ ions across the plasma membrane. To determine whether this also occurs in mammalian neurons and whether this could underlie the inter-species difference between rodents and primates, we have tested the effects of NaP on intracellular Ca²⁺ levels ([Ca²⁺]_i) in rat and monkey motor neurons in vitro. Motor neurons present in spinal cord slices from rhesus monkey embryos (E37 and 56) and from rat E16 were dissected and cultured on glass coverslips. Following 2 weeks (rhesus) or 2-3 days (rat) in culture, neurons were loaded with fura-PE3/AM, and examined for [Ca²⁺]_i changes in response to NaP. Rhesus motor neurons were identified by immunostaining for Islet-1 (MN specific antigen) and neuron specific enolase (NSE). Motor neurons from both species exhibited dose-dependent NaP-evoked increases in [Ca²⁺]_i However, the dose-response curve for the Rhesus motor neurons was significantly shifted to the right of the rat dose-response curve, whereas the overall amplitude of the Ca²⁺ rise was similar in both species. As shown previously for the Aplysia neurons, the action of NaP is attenuated by SKF 96365, an inhibitor of store-operated calcium entry. In contrast the action of NaP is unaffected by nifedipine and tetrodotoxin, blockers of voltage-dependent Ca²⁺ and Na⁺ channels, respectively, or by ouabain, an inhibitor of the plasma membrane Na⁺/K⁺ ATPase. Our results indicate that the NaP-induced increase in [Ca²⁺]_i is conserved across species and suggest that the toxicological sensitivity of rodent over primate to pyrithione could be due to the enhanced sensitivity of rodent motor neurons to NaP-evoked intracellular Ca²⁺ elevation.