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Results show that the surface protein PFS48/45 of male gametes of Plasmodium falciparum mediates fertilization process as evidenced by mutant male gamete's inability to penetrate fertile female gametes.

7B2 is a new type of molecular chaperone which associates with the prohormone cleavage enzyme PC2 and controls the maturation activation of pro PC2 by transient protein-protein interaction in the final stages of the secretory pathway. Pulse-chase analysis reveals that there is early transient interaction between 7B2 and pro PC2, followed by dissociation of 7B2, pro PC2 and prohormone in the later stages.

The 7B2 neuroendocrine polypeptide, which negatively regulates the PC2 prohormone convertase, altered peptide hormone levels. The polypeptide and the enzyme were both components of regulated secretory pathways, associated with endocrine and neuron cells. PC2 was insensitive to the processed form of 7B2.

Background Radiation therapy (RT) as part head and neck cancer treatment often leads to irradiation of surrounding normal tissue, such as mandibular bone. A reduced reparative capacity of the bone can lead to osteoradionecrosis (ORN). Hyperbaric oxygen therapy (HBOT) is used to treat ORN, based on its potential to raise the oxygen tension in tissues. However, prevention of radiation-induced damage is of great interest. Our purpose was to investigate whether HBOT could prevent radiation-induced damage to murine mandibles. Methods Twenty-eight mice were irradiated in the head and neck region with a single dose (15 Gy) and half of them were subsequently subjected to HBOT. Another 14 mice did not receive any treatment and served as controls. Ten and 24 weeks after RT, mandibles were harvested and analysed histologically and by microcomputed tomography (micro-CT). Results Micro-CT analysis showed a reduction in relative bone volume by RT, which was partly recovered by HBOT. Trabecular thickness and separation were also positively influenced by HBOT. Morphologically, HBOT suppressed the osteoclast number, indicating decreased resorption, and decreased the amount of lacunae devoid of osteocytes, indicating increased bone viability. Conclusions HBOT was able to partly reduce radiation-induced effects on microarchitectural parameters, resorption, and bone viability in mouse mandibles. HBOT could therefore potentially play a role in the prevention of radiation-induced damage to human mandibular bone. [ABSTRACT FROM AUTHOR]

Examines the chemical complex dissociation between neuroendocrine chaperone 7B2 and prohormone convertase PC2 and its association with proPC2 maturation. Factual background on the 7B2 neuroendocrine protein; In vitro conversion of the synthesized proPC2 and inhibition by recombitant 7B2; Prevention of autocatalytic enzyme conversion.

The neuroendocrine-specific polypeptide 7B2 is a constituent of the regulated secretory pathway. Recently, 7B2 was found to function as a molecular chaperon for phohormone convertase PC2. This report describes the genomic organization of the 7B2 gene which consists of six exons. Exon 1 corresponds to the 5'-untranslated mRNA region, while exons 2 and 3 encode the signal peptide and the amino-terminal half of the 7B2 protein that is distantly related to a subclass of molecular chaperones. The carboxy-terminal half of 7B2, responsible for its inhibitory action on PC2, is encoded by exons 4-6. Primer-extension analysis showed that the human 7B2 gene is transcribed from multiple transcription-initiation sites. The human 7B2 gene promoter contains cAMP-responsive element, an AP-1 site, and several Pit-1/GHF-1 binding domains and heat-shock-element-like sequences but no obvious TAT or CAAT boxes. Of further interest is the finding of two DNA elements which are common to the promoter regions of the 7B2 gene and other genes selectively expressed in neuroendocrine tissues. [ABSTRACT FROM AUTHOR]