Interference structures in the differential cross-sections for inelastic scattering of NO by AR

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Regulated acid-base transport in the collecting duct

The renal collecting system serves the fine-tuning of renal acid-base secretion. Acid-secretory type-A intercalated cells secrete protons via a luminally expressed V-type H(+)-ATPase and generate new bicarbonate released by basolateral chloride/bicarbonate exchangers including the AE1 anion exchanger. Efficient proton secretion depends both on the presence of titratable acids (mainly phosphate) and the concomitant secretion of ammonia being titrated to ammonium. Collecting duct ammonium excretion requires the Rhesus protein RhCG as indicated by recent KO studies. Urinary acid secretion by type-A intercalated cells is strongly regulated by various factors among them acid-base status, angiotensin II and aldosterone, and the Calcium-sensing receptor. Moreover, urinary acidification by H(+)-ATPases is modulated indirectly by the activity of the epithelial sodium channel ENaC. Bicarbonate secretion is achieved by non-type-A intercalated cells characterized by the luminal expression of the chloride/bicarbonate exchanger pendrin. Pendrin activity is driven by H(+)-ATPases and may serve both bicarbonate excretion and chloride reabsorption. The activity and expression of pendrin is regulated by different factors including acid-base status, chloride delivery, and angiotensin II and may play a role in NaCl retention and blood pressure regulation. Finally, the relative abundance of type-A and non-type-A intercalated cells may be tightly regulated. Dysregulation of intercalated cell function or abundance causes various syndromes of distal renal tubular acidosis underlining the importance of these processes for acid-base homeostasis

Allografts Use in Nasal Reconstruction

The outcomes of destructive processes of the nasal structure such as infection, chronic inflammation, or resective procedures can lead to the need of complex reconstruction of the nasal framework [1]. Various types of grafts and implants have been employed [2]. When dealing with a nasal reconstruction of whatever kind, the surgeon is faced by a clinical dilemma: which is the best material for reconstructive purposes in that patient? The materials used for augmentation are therefore an important issue among reconstructive rhinoplasty surgeons [3, 4]. A basic differentiation must be outlined between the terms of grafts and implants: a graft is made of tissue either from the same patient (autograft) or from a member of the same species (homograft). Implants are synthetic and if implantable are called alloplasts [5]. Alloplastic material is deemed desirable if noncarcinogenic, nonallergenic, readily available, resistant to mechanical strain, and entirely reabsorbable and still reliable. It is commonly perceived that autologous grafts are the first choice for augmenting the nose; unfortunately, this material is not always available or sufficient in cases of atrophic changes of the nose of whatever cause to fulfill the needs. However, limited availability, unpredictable resorption rates, difficulty of handling, and donor-site morbidity are possible drawbacks. In such instances, other choices must be considered, and alloplastic materials can represent an attractive alternative tool to take into account [6]. On the other hand, their efficacy complications and limited usage are 192 debated, such not uniform feelings and disputed possibilities have given rise to the development of different technologies to possibly reach ideal grafting substance (Fig. 16.1). In Western countries, surgeons prefer costal or auricular cartilage when septal cartilage is not available or insufficient, whereas alloplastic materials are more widely used in Asia [7]. Since the very beginning of the rhinoplasty history, many efforts have been made over time to use implants such as gold, iron, ivory, paraffin, celluloid, glass, and cork, eventually discorded due to unsurpassable troubles [8] (Figs. 16.2 and 16.3). Today, commonly used alloplastic materials are silicon, Gore-Tex® (Surgiform Technology, SC, USA), Medpor® (Stryker Corporate, a b c d Fig. 16.1 (a) CT scan and pathology specimen showing foreign body cystic reaction. Fibrous capsule with implant inside. (b) Latex implant of the dorsum (implanted 10 years previously), at moment inflamed, cistic and mobile, removed. (c) The removing of latex implant. (d) A fibrous capsule with implant inside P. G. Giacomini et al. 193 a b Fig. 16.2 (a) Kirschner steel wire and preserved costal cartilage implant of dorsum (10 years previously), for cocaine abuse outcomes. (b) Picture 6 months after removal a b Fig. 16.3 (a) CT scan, showing implant and the infected. (b) Mobile dorsal implant 16 Allografts Use in Nasal Reconstruction 194 MI, USA), and polydioxanone plate (PDS Flexible Plate, Johnson & Johnson Company, Langhorne, Pennsylvania, USA) [9]. An overview of their pros and cons will be conducted on the basis of the literature data and personal experience to highlight their possible use in case of atrophic nose outcomes that require surgical correction. Some exemplificative clinical cases of patients treated at the ENT Dept., School of Medicine, University of Rome Tor Vergata, at Nose Plastic Surgery Clinic in the past 10 years for complications associated with alloplastic materials used in atrophic rhinitis of various etiologies are reported. Clinical profiles: eight cocaine abuse, one purulent chronic infection, two outcomes of facial trauma, and one previous nasal surgery. M/F ratio: 1:4. The patients’ age ranged from 42 to 81 years (mean: 49 years). The follow-up period was 3–15 years (mean: 4.2 years). All had been treated elsewhere for augmentation rhinoplasty with alloplastic materials end eventually revised for complications occurred. Type of alloplastic materials used, complications developed, and results obtained were revised by medical charts, photo documentation, and histopathologic data examined. Literature data were considered in order to define alloplastic materials possibilities in this kind of nasal reconstruction