Neuropeptide substance P alters stem cell fate to aid wound healing and promote epidermal stratification through asymmetric stem cell divisions.

Loss of sensory innervation delays wound healing and administration of the neuropeptide substance P improves re-epithelialization. Keratinocyte hyperproliferation post-wounding may result from symmetric stem cell (SC) self-renewal, asymmetric SC self-renewal, committed progenitor divisions, or a combination of these. However, the effects of sensory denervation and of neuropeptides on SC proliferation are not known. Here we show that early after wounding both asymmetric and symmetric SC self-renewal increase, without significant committed progenitor (CP) activation. Decreased sensory innervation is associated with a decrease in both SC and CP proliferation. Based on previous work showing that substance P is decreased in capsaicin-treated mice and improves wound healing in normal skin, we examined the effects of substance P on SC and CP proliferation during wound healing. Substance P restored asymmetric SC proliferation in skin with decreased sensory innervation, both at baseline and following wounding. Epidermis with decreased sensory innervation was severely thinned. Consistent with this, substance P-induced asymmetric SC proliferation resulted in increased stratification in skin with both normal and decreased innervation. Lapatinib prevented the substance P-induced increase in asymmetric SC divisions in murine epidermis, as well as the increase in epidermal stratification, suggesting that asymmetric SC divisions are required for epidermal stratification.

Drug susceptibility of Neisseria isolates from patients attending clinics for sexually transmitted diseases in Addis Ababa.

Sixty eight Neisseria gonorrhoeae strains were isolated from endocervical and urethral discharge of 233 patients attending health centres for sexually transmitted diseases (STDs) in Addis Ababa, were identified following conventional procedures and tested for susceptibility to penicillin, ampicillin, trimethoprim-sulphamethoxazole (bactrim), chloramphenicol, erythromycin and kanamycin by the agar disc diffusion technique. Penicillinase producing N. gonorrhoeae (PPNG) were identified using the chromogenic cephalosporin method and comprised 70% of the isolates. Seventy seven per cent, 73%, 64% and 17% of the isolates were found to be resistant to penicillin, ampicillin, bactrim and kanamycin, respectively. However, no resistance to erythromycin and chloramphenicol was observed. Multiple drug resistance was found to be 67%. This is a cause for concern in the control and treatment of gonococci.