Unfolding and refolding of bovine serum albumin at acid pH: ultrasound and structural studies.

Serum albumin is the most abundant protein in the circulatory system. The ability of albumins to undergo a reversible conformational transition, observed with changes in pH, is conserved in distantly related species, suggesting for it a major physiological role possibly related to the transport of small molecules including drugs. We have followed changes of bovine serum albumin (BSA) in volume by densimetry and in adiabatic compressibility during its conformational transition from pH 7-2, using ultrasound measurements. In parallel, circular dichroism was measured. The volume and adiabatic compressibility decrease from pH 4 to 2. The change in ellipticity shows a decrease over the same pH range from 70% to 40% of its alpha-helix content. Sorbitol, at concentrations from 0 to 2 M, led to the progressive restoration of BSA volume and compressibility values, as well as a substantial recovery of its original alpha-helix content. This finding implies that the compressibility variation observed reflects the conformational changes during the transition. The mutual interactions of the mechanical properties and structural features of BSA reported here are important in biotechnology for research in material sciences and for the design and the development of new, tailor-made drug carriers.

Bilateral pulmonary lobe transplantation: left lower and right middle and lower lobes.

It is difficult to find lungs of appropriate size for double-lung transplantation in teenagers and small adults. Nevertheless, many young patients suffering from cystic fibrosis are waiting for lung transplantation. We have performed two bilateral lobar transplantations (left lower lobe plus right middle and lower lobe) with good recovery. Details of the technique are described.

[Healing of bronchial anastomoses in single and double pulmonary transplantations]. / La cicatrisation des anastomoses bronchiques dans les transplantations uni- et bipulmonaires.

Bilateral single lung transplantation (BSLT) (the procedure of choice for double lung replacement) and single lung transplantation (SLT) have at present a low incidence of anastomotic problems. In our experience, we have recorded no death related to anastomotic problems and 4 complications occurred for 33 anastomoses with a follow up of at least 2 months. A stent was temporarily inserted for two patients. The decrease of anastomotic complications is confirmed in the literature. It is one of the reasons why the number of SLT and BSLT performed all over the world increases rapidily to the detriment of heart lung transplantation.

Tracheal sleeve resection for iatrogenic stenoses (subglottic laryngeal and tracheal).

Since 1975 200 tracheal sleeve resections for iatrogenic tracheal and subglottic laryngeal stenoses have been performed in our institution. Preoperative Nd:YAG laser is of paramount help in opening the stenoses. Tracheography is usually performed to specify the length of the stenosis and the distance from the vocal cords. Operative procedures are described. One hundred seventy five (87.5%) patients are definitely cured, but in this group 16 patients required a Montgomery tube for 6 months to 1 year to recover a normal tracheal diameter. Two patients needed a second tracheal sleeve resection. Nine (4.5%) patients died, and 16 (8%) had recurrent stenoses. Stenoses in these patients were treated with use of a tracheostomy tube, a permanent Montgomery tube, or an endotracheal stent. Partial anterior cricoid resections performed in 21 patients have had the same results as those of the whole series. Twenty one laryngeal releases were performed and proved to be efficient and safe. In our experience complications can be avoided by good selection and preparation of the patients, accurate identification of the level and length of the stenosis, and meticulous technique.

Bilateral single lung transplantation. Complications and results in 14 patients.

Between November 1989 and April 1991, 14 bilateral single lung transplantations (BSLT) were performed at our institution using the technique we have described without omentoplasty and rarely cardiopulmonary bypass. The indications included emphysema (8), cystic fibrosis (3), infected fibrosis (1), alveolar microlithiasis (1) and lymphocytic interstitial pneumonitis (1). Maximum mean pulmonary artery pressure was 53 mmHg and minimal right ventricular ejection fraction was 15%. Two patients experienced bronchial complications: 1 complete left bronchial dehiscence, 1 late partial stenosis which required a temporary insertion of a stent. One patient had a posterior dehiscence which healed spontaneously. Five patients died postoperatively (3 of infection, 1 after a volume mismatch and 1 after a circulating anticoagulant). BSLT is the technique of choice for double lung transplantation in adults and heart lung transplantation has very few indications in infected end-stage pulmonary disease. We hope that modification of our immunosuppressive regimen will decrease postoperative mortality.

[Single lung transplantation]. / La greffe unipulmonaire.

Thirteen single lung transplantations have been performed in our department for non-infected end-stage lung diseases. Two patients died after surgery; a female patient died of uterine carcinoma one year and six months after the operation. The remaining ten patients are alive; they have resumed an active life and often working. The number of single lung transplantation is rapidly growing in the world, whereas heart-lung transplantation is regressing considerably.

[Donor-recipient lung volume matching in double lung transplantation. Value of left lower lobe graft]. / Adéquation volumétrique donneur-receveur en greffe bipulmonaire. Intérêt de la greffe lobaire inférieure gauche.

For double lung transplantation, lung volume matching is easier comparing the predicted total lung capacities of the donor and recipient and the recipient's true TLC. The major concern in the inability to close the chest when the donor lungs are too large. The technique reported of left lower lobe implantation during bilateral single lung transplantation might be of great value in patients with small lung volume.

[Double lung transplantation. The "bilateral single" graft]. / Greffe bipulmonaire. La double unilatérale.

We present 10 cases of a new double lung transplantation technique: following, then the other, without requiring cardiopulmonary bypass. This "bilateral single" lung transplantation procures all the advantages of single lung transplantation.

[A new technique for double lung transplantation. "The bilateral single lung transplantation". Apropos of ten operations]. / Une nouvelle technique de greffe bipulmonaire. "La double unilatérale". A propos de dix interventions.

The technique of enbloc double lung transplantation described by the Toronto team, with cardiopulmonary bypass, cardioplegia, and tracheal suture is complicated by problems of tracheal anastomosis for its authors. Single lung transplantation has a more straight forward postoperative course and bronchial complications are moderate. We present a new technique of lung transplantation, the "bilateral single lung transplantation". It consists, via a single anterior horizontal incision, of successively performing two single lung transplantations without bypass. This operation has been performed ten times since November 1989. As expected, bronchial healing has been excellent.