Biomedical subjects

V Valderrabano

Publications and source records attributed to V Valderrabano.

4 recordsLinked to original sources

PubMed2001

Distribution of transcellular calcium and sodium transport pathways along mouse distal nephron.

The organization of Na(+) and Ca(2+) transport pathways along the mouse distal nephron is incompletely known. We revealed by immunohistochemistry a set of Ca(2+) and Na(+) transport proteins along the mouse distal convolution. The thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC) characterized the distal convoluted tubule (DCT). The amiloride-sensitive epithelial Na(+) channel (ENaC) colocalized with NCC in late DCT (DCT2) and extended to the downstream connecting tubule (CNT) and collecting duct (CD). In early DCT (DCT1), the basolateral Ca(2+)-extruding proteins [Na(+)/Ca(2+) exchanger (NCX), plasma membrane Ca(2+)-ATPase (PCMA)] and the cytoplasmic Ca(2+)-binding protein calbindin D(28K) (CB) were found at very low levels, whereas the cytoplasmic Ca(2+)/Mg(2+)-binding protein parvalbumin was highly abundant. NCX, PMCA, and CB prevailed in DCT2 and CNT, where we located the apical epithelial Ca(2+) channel (ECaC1). Its subcellular localization changed from apical in DCT2 to exclusively cytoplasmic at the end of CNT. NCX and PMCA decreased in parallel with the fading of ECaC1 in the apical membrane. All three of them were undetectable in CD. These findings disclose DCT2 and CNT as major sites for transcellular Ca(2+) transport in the mouse distal nephron. Cellular colocalization of Ca(2+) and Na(+) transport pathways suggests their mutual interactions in transport regulation.

Animals↗

PubMed2001

[Total ankle joint replacement].

We evaluated the short- to mid-term results of an unconstrained total ankle prosthesis (S.T.A.R.) with uncemented fixation. Seventy-nine consecutive ankle replacements were performed in 76 patients between 1996 and 2000. The initial diagnosis was posttraumatic osteoarthrosis in 51 cases (64%), primary osteoarthrosis in 14 cases (18%), and systemic joint affection in 14 cases (18%). Although 29 revision operations were necessary, all implants became fix, and no implants have been removed. At the last follow-up control, 38 patients (62%) were very satisfied, 20 patients (33%) were satisfied, and 3 patients (5%) were satisfied with reservations. The obtained range of motion was 35 degrees (range, 15 to 55 degrees), with a maximal plantarflexion of 27 degrees (range, 15 to 45 degrees) and dorsiflexion of 8 degrees (-3 to 20 degrees). The AOFAS-Hindfoot-Score of the 61 patients scored 84 points (range, 51 to 100 points). After settling of the implants within 6 weeks, no migration was noted in any case, and all implants were considered to be stable. The favorable results were considered to be a result of the mechanical properties of the S.T.A.R. total ankle prosthesis that allow for unconstrained motion. The rate of revisions, however, was too high, and it was considered to be a result of the design of tibial and talar component, the tibial fixation and the poor instrumentation. Nevertheless, total ankle replacement was shown to be a viable alternative to ankle arthrodesis. A longer follow-up is, however, mandatory to evaluate the long-term prognosis.

Adult↗

PubMed1999

Lengthening of the lateral column and reconstruction of the medial soft tissue for treatment of acquired flatfoot deformity associated with insufficiency of the posterior tibial tendon.

We analyzed our results of surgery for acquired flatfoot deformity after dysfunction of the posterior tibial tendon. This included lengthening the proximal lateral column by calcaneal osteotomy and reconstructing the medial soft tissue. Nineteen patients (9 women and 10 men; average age, 52.9 years [range, 24-72 years]) were treated for stage II and stage II-III insufficiency of the posterior tibial tendon. The medial soft tissue surgery included 18 reconstructions of the tendon, 11 transfers of the flexor digitorum longus tendon, 13 repairs of the deltoid ligament, and 3 repairs of the spring ligament. At follow-up (mean, 23.4 months), all patients had satisfactory restoration of their medial longitudinal arch, reduction of abduction in the forefoot, and restored height in the arch. All patients were able to bear weight fully on the foot that underwent surgery, and all but one were satisfied with the result achieved. The clinical result was rated as excellent in 6, good in 11, and fair in 2 cases. In all but one case, no loss of achieved correction in the foot was found. In one case, the calcaneocuboid joint had to undergo arthrodesis after 5 months because of painful degenerative joint disease. In the pes planovalgus and abductus deformities occurring in stage II disease, calcaneal osteotomy and reconstruction of the medial tendon and ligament seem to play a significant role in operative management. This was the case only when degenerative joint disease and significant subluxation of the subtalar or talonavicular joint or both had not already occurred. They seem to function by restoring more normal biomechanics, which allows reconstructed or transferred tendon to function successfully.

Adult↗

PubMed1999

[Lateral column lengthening by calcaneal osteotomy combined with soft tissue reconstruction for treatment of severe posterior tibial tendon dysfunction. Methods and preliminary results].

The purpose of this paper is to present principle and technique of proximal lateral column lengthening by calcaneal osteotomy and to critically analyze our preliminary results. 16 patients (7 female, 9 male; average age 52.3 years [24-72 years]) were treated for stage II to III posterior tibial tendon insufficiency by calcaneal osteotomy and medial soft tissue reconstruction (tendon reconstruction, 15; tendon transfer, 8; deltoid ligament repair, 10). When the AOFAS Ankle-Hindfoot Rating Scale was applied, these patients were shown to have significantly increased their scores from an average preoperative value of 49.1 to a mean postoperative value of 91.1 after a mean follow-up of 24.6 months. In all but one case no loss of achieved foot correction was noted. In one case, a fusion of the calcaneocuboid joint had to be performed after 5 months due to painful degenerative joint disease. At follow-up, all patients had satisfactory restoration of their medial longitudinal arch, reduction of forefoot abduction, and restored arch height. All patients were able to fully weight-bear the operated foot, and all patients were satisfied with the achieved result. In the pes planovalgus deformity occurring in stage II to III (as significant degenerative joint disease has not already occurred), osteotomies appear to have a significant role in the operative management and to function by restoring more normal biomechanics, thus allowing tendon reconstruction and tendon transfers to return to successful function.

Adult↗