Multimodal evaluation of donor site morbidity in transgender individuals after phalloplasty with a free radial forearm flap: a case-control study

BACKGROUND

In phalloplasty, there is a lack of standardized follow-up examinations of motor function and strength after harvesting oversized radial forearm free flaps (RFFF).

METHODS

We evaluated the donor site of 20 transmen after phalloplasty, using a multimodal, standardized approach, assessing the following parameters: opposition of the thumb, composite range of motion of the finger joints, grip strength, mobility of the wrist, lesion of the superficial branch of the radial nerve, the dorsal branch of the ulnar nerve, the sensation of pain, and cold intolerance. The contralateral, nonoperated forearm was used as a control.

RESULTS

No impairment of the mobility of the thumb (Kapandji score median 10, range 5-10) or fingers (all fingers at both sides pulp-to-palm 0 cm, nail-to-table 0 cm) were detected. Grip strength (median 36,3kg, p=0.629) and wrist extension (62.5°vs.70°, p=0.357), flexion (70°vs.70°, p=0.535), pronation (90°vs.90°), supination (90°vs.90°), radial (30°vs.30°, p=0.195), and ulnar deviation (40°vs.50°, p=0.125) did not statistically differ between donor and control hand. Injury of the dorsal branch of the ulnar nerve was uncommon (0% hypoesthesia, 10% positive Tinel's sign). We did not observe any persistent pain of the donor forearm (NRS median 0, range 0-9). We did observe irritation of the superficial branch of the radial nerve (hypoesthesia 40%, neuroma 45%).

CONCLUSION

The harvest of an oversized RFFF for phalloplasty does not cause any significant difference in motor function or strength between the donor and nonoperated hand. A potential risk of injuring the radial nerve branch is to be avoided. An aesthetic impairment could be addressed in future studies.

Inflammation-associated regulation of RGS in astrocytes and putative implication in neuropathic pain

Background

Regulators of G-protein signaling (RGS) are major physiological modulators of G-protein-coupled receptors (GPCR) signaling. Several GPCRs expressed in both neurons and astrocytes participate in the central control of pain processing, and the reduced efficacy of analgesics in neuropathic pain conditions may rely on alterations in RGS function. The expression and the regulation of RGS in astrocytes is poorly documented, and we herein hypothesized that neuroinflammation which is commonly observed in neuropathic pain could influence RGS expression in astrocytes.

Methods

In a validated model of neuropathic pain, the spared nerve injury (SNI), the regulation of RGS2, RGS3, RGS4, and RGS7 messenger RNA (mRNA) was examined up to 3 weeks after the lesion. Changes in the expression of the same RGS were also studied in cultured astrocytes exposed to defined activation protocols or to inflammatory cytokines.

Results

We evidenced a differential regulation of these RGS in the lumbar spinal cord of animals undergoing SNI. In particular, RGS3 appeared upregulated at early stages after the lesion whereas expression of RGS2 and RGS4 was decreased at later stages. Decrease in RGS7 expression was already observed after 3 days and outlasted until 21 days after the lesion. In cultured astrocytes, we observed that changes in the culture conditions distinctly influenced the constitutive expression of these RGS. Also, brief exposures (4 to 8 h) to either interleukin-1β, interleukin-6, or tumor necrosis factor α caused rapid changes in the mRNA levels of the RGS, which however did not strictly recapitulate the regulations observed in the spinal cord of lesioned animals. Longer exposure (48 h) to inflammatory cytokines barely influenced RGS expression, confirming the rapid but transient regulation of these cell signaling modulators.

Conclusion

Changes in the environment of astrocytes mimicking the inflammation observed in the model of neuropathic pain can affect RGS expression. Considering the role of astrocytes in the onset and progression of neuropathic pain, we propose that the inflammation-mediated modulation of RGS in astrocytes constitutes an adaptive mechanism in a context of neuroinflammation and may participate in the regulation of nociception.

Inflammatory chemokine release of astrocytes in vitro is reduced by all-trans retinoic acid

The production of chemokines by astrocytes constitutes an important component of neuroinflammatory processes in the brain. As the transcriptional activator retinoic acid (RA), used for chemotherapy and dermatological applications, exerts anti-inflammatory effects on monocytes and lymphocytes, we have tested whether the physiologically occurring isomer, all-trans RA, affects chemokine expression by astrocytes. Under control conditions, primary cultures of murine cortical astrocytes expressed no or very low levels of CCL and CXCL chemokines. After treatment with bacterial lipopolysaccharides to simulate inflammation in vitro, we detected a strong increase in the release of CCL2 (to > 4 ng/mL in cell culture supernatant), CCL3 (> 20 ng/mL), CCL5 (> 25 ng/mL), CXCL1 (> 30 ng/mL) and CXCL2 (> 20 ng/mL). Although simultaneous exposure to RA did not significantly affect this response, 12 h pre-treatment with 0.1 microM all-trans RA strongly suppressed mRNA expression and protein release of all chemokines. The anti-inflammatory activity of RA engaged RA and retinoid X receptors and correlated with a decreased expression of the lipopolysaccharides co-receptor CD14. A minor reduction of nuclear NF-kappaB was observed but not significant, activation of Jun amino-terminal kinase, p38 and signal transducer and activator of transcription 3 were not altered by RA. The results suggest that retinoids should be further investigated as candidates for the treatment of neuroinflammation.

Anti-inflammatory effect of retinoic acid on prostaglandin synthesis in cultured cortical astrocytes

Prostanoids are important mediators of inflammation and pain signaling. Although it is now well accepted that astrocytes participate in inflammatory reactions in the CNS, the molecular regulation of this activity is still largely unknown. Specifically, the regulation of prostanoid synthesis by this type of glia remains to be resolved. Recent evidence suggests that the transcriptional regulator retinoic acid (RA) is involved in regulation of the immune response. We have investigated the expression pattern of the enzymes that catalyze prostanoid and leukotriene synthesis in cultured cortical astrocytes, their stimulation by lipopolysaccharides (LPS) and their regulation by RA. The data indicate that astrocytes are an important source of prostaglandins (PGs) and that RA reduces their inflammatory biosynthesis. LPS treatment induced the expression of enzymes for the production of arachidonic acid and PGs but caused down-regulation of a PG degrading enzyme and of leukotriene synthesizing enzymes that compete with PG synthesis. Consequently, the secretion of the PGE(2) was highly increased after LPS exposure. RA counteracted the inflammatory regulation of cyclooxygenase (COX)-2 mRNA and protein in astrocytes and thereby reduced the synthesis of PGE(2) by approximately 60%. In the absence of LPS, RA enhanced the expression of COX-1 mRNA. In conclusion, RA might be effective in suppressing inflammatory processes in the brain by inhibiting PG synthesis.

RAR/RXR and PPAR/RXR signaling in neurological and psychiatric diseases

Retinoids are important signals in brain development. They regulate gene transcription by binding to retinoic acid receptors (RAR) and, as was discovered recently, a peroxisome proliferator-activated receptor (PPAR). Traditional ligands of PPAR are best known for their functions in lipid metabolism and inflammation. RAR and PPAR are ligand-activated transcription factors, which share members of the retinoid X receptor (RXR) family as heterodimeric partners. Both signal transduction pathways have recently been implicated in the progression of neurodegenerative and psychiatric diseases. Since inflammatory processes contribute to various neurodegenerative diseases, the anti-inflammatory activity of retinoids and PPARgamma agonists recommends them as potential therapeutic targets. In addition, genetic linkage studies, transgenic mouse models and experiments with vitamin A deprivation provide evidence that retinoic acid signaling is directly involved in physiology and pathology of motoneurons, of the basal ganglia and of cognitive functions. The activation of PPAR/RXR and RAR/RXR transcription factors has therefore been proposed as a therapeutic strategy in disorders of the central nervous system.