Hspa9 is required for pronephros specification and formation in Xenopus laevis.

BACKGROUND: Development of the pronephros in Xenopus laevis is largely dependent on retinoic acid signaling at the time of kidney field specification with the simultaneous occurrence of a necessary calcium signaling. At the crossroads of these two signaling pathways, we studied the role of Hspa9 (heat shock 70 kDa protein 9) encoding a mitochondrial chaperone in pronephros development. RESULTS: We first showed that Hspa9 is highly expressed in the pronephros territory and elongating nephric duct. We then observed that upon reduced retinoic acid signaling hspa9 expression was reduced as pax8 and pax2. Overexpression of hspa9 enlarged the pax8 positive pronephros territory, leading to a larger pronephric tubule. Loss of function of hspa9 in the kidney field using morpholino approach severely reduced pax8 expression and pronephros formation. Phenotypic rescue was achieved by co-injection of the full-length murine Hspa9 mRNA. However, no rescue was observed when Hspa9 mRNA lacking the mitochondrial-targeting sequence was injected, as this truncated form is able to interfere with pronephros formation when injected solely. CONCLUSIONS: Hspa9 is an important mediator for pronephros development through modulation of pax8. Mitochondrial functions of hspa9 are likely to be involved in specification of pronephric cell fate.

Ligamentoplasty with interposition of the proximal interphalangeal joint in the treatment of unicondylar osteochondral defects: a cadaveric feasibility study.

BACKGROUND: Injuries to the proximal interphalangeal (PIP) joint are common and complex. However, the treatment of osteochondral defects of the head of the proximal phalanx has rarely been described. Herein, we propose a new technique for the management of unicondylar defects of the proximal phalanx that can restore joint amplitudes and provide PIP stability. METHODS: In this cadaveric feasibility study, unicondylar defects were generated using striking wedges and chisels. First, a transverse tunnel measuring 2 mm in diameter passing through the head of the proximal phalanx was made. A second tunnel at the base of the middle phalanx with the same diameter was then created. The hemitendon of the flexor carpi radialis graft was passed through each of these tunnels. The proximal end of the graft was interposed in the area with a loss of bone substance. The ligamentoplasty was then tensed and fixed by two anchors on the proximal phalanx. Joint amplitudes and frontal stability were measured preoperatively and postoperatively. RESULTS: There was no significant change in the joint's range of motion: preoperatively, the mean mobility arcs were -2° to 113.80°, and they were -2° to 110° after the procedure (P=0.999). There was no significant difference in joint stability (P>0.05). CONCLUSIONS: Ligamentoplasty with PIP interposition appears to be a possible solution for the management of unicondylar defects of the proximal phalanx. An evaluation of clinical results is planned in order to definitively confirm the validity of this procedure.

C5-8 neonatal brachial plexus palsy. Operative findings, reconstructive strategy and outcome.

From 1998 to 2014, we performed primary brachial plexus repair in 260 children with neonatal brachial plexus palsy. Thirty-three presented with a C5-8 palsy and 24 were reviewed for this study. The surgical strategy was to focus on repairing the upper trunk. Secondary surgical procedures were performed in 21 patients, mainly for shoulder external rotation deficit or weak wrist extension. After a mean follow-up of 9.7 years (range 3 to 19), the median Mallet score for the shoulder was 9.5 and the mean Raimondi score for the hand was 3.3. Median active movement scale was 5, 7 and 5.5 for the deltoid, biceps and triceps, respectively. We conclude that primary C5-8 brachial plexus reconstruction provides restoration of elbow flexion and most patients have a sensitive and functional hand. We also found that secondary surgery to improve shoulder and wrist function is often necessary, which should initially be explained to the family.Level of evidence: IV.