Coexistence and upregulation of three types of opioid receptors, mu, delta and kappa, in human hypertrophic scars

Solid-phase synthetic strategy and bioevaluation of a labeled delta-opioid receptor ligand Dmt-Tic-Lys for in vivo imaging

A general solid-phase synthetic strategy is developed to prepare fluorescent and/or lanthanide-labeled derivatives of the delta-opioid receptor (deltaOR) ligand H-Dmt-Tic-Lys(R)-OH. The high delta-OR affinity (K(i) = 3 nM) and desirable in vivo characteristics of the Cy5 derivative 1 suggest its usefulness for structure-function studies and receptor localization and as a high-contrast noninvasive molecular marker for live imaging ex vivo or in vivo.

Peripheral mechanisms of pain and analgesia

This review summarizes recent findings on peripheral mechanisms underlying the generation and inhibition of pain. The focus is on events occurring in peripheral injured tissues that lead to the sensitization and excitation of primary afferent neurons, and on the modulation of such mechanisms. Primary afferent neurons are of particular interest from a therapeutic perspective because they are the initial generator of noxious impulses traveling towards relay stations in the spinal cord and the brain. Thus, if one finds ways to inhibit the sensitization and/or excitation of peripheral sensory neurons, subsequent central events such as wind-up, sensitization and plasticity may be prevented. Most importantly, if agents are found that selectively modulate primary afferent function and do not cross the blood-brain-barrier, centrally mediated untoward side effects of conventional analgesics (e.g. opioids, anticonvulsants) may be avoided. This article begins with the peripheral actions of opioids, turns to a discussion of the effects of adrenergic co-adjuvants, and then moves on to a discussion of pro-inflammatory mechanisms focusing on TRP channels and nerve growth factor, their signaling pathways and arising therapeutic perspectives.

Characterization of angiotensin-converting enzyme expression during epidermis morphogenesis in humans: a potential marker for epidermal stem cells

BACKGROUND

Recent evidence has revealed that angiotensin-converting enzyme (ACE) participates in cutaneous wound healing and contributes to the pathophysiological process of some skin diseases. However, little is known about the role of ACE in epidermis morphogenesis during development.

OBJECTIVE

To clarify the expression pattern of ACE during embryonic development of human skin.

METHODS

Skin samples were obtained from aborted fetuses at different gestational ages and from healthy individuals. Localization of ACE, together with beta(1)-integrin, keratin 19 (K19) and p63 was examined by immunofluorescence and immunohistochemical staining.

RESULTS

In human fetal skin, at 11-13 weeks of gestation, ACE-positive cells were observed in the primitive epidermis. As the fetuses developed, ACE-positive cells appeared in all the epidermal layers. From 21 weeks of gestation, ACE expression was largely restricted to the basal layer of the fetal epidermis. In contrast, ACE-positive cells were found only in the adult skin basal layer which harbours epidermal stem cells. To explore the possible link between ACE and epidermal stem cells, we further examined the expression of beta(1)-integrin, K19 and p63, the putative markers for epidermal stem cells. Consistent with the results of ACE expression, from 21 weeks of gestation, the expression of beta(1)-integrin, K19 and p63 was mainly confined to the basal layer. Immunofluorescent double labelling revealed that ACE-positive cells substantially overlapped with beta(1)-integrin-, K19- and p63-positive cells.

CONCLUSIONS

Our results suggest that ACE may play a role in human epidermis morphogenesis during fetal life and serve as an unrecognized marker for keratinocyte progenitor cells.