Process of ammonia removal from anaerobic digestion and associated ammonium sulphate production: Pilot plant demonstration.

A process for the continuous extraction of ammonia from anaerobic digesters is proposed. In this process, a portion of the sludge treated in the digesters is continuously withdrawn and transferred to a thin film evaporator (TFE) unit, where the ammonia is stripped through a biogas stream. The ammonia-rich biogas is treated with a sulfuric acid/water solution in a reactive absorption unit, with production of ammonium sulphate. The chemistry of a CH4/CO2/NH3 gas phase in thermodynamic equilibrium with a liquid sulfuric acid/water solution is investigated theoretically, with focus on the simultaneous absorption of CO2 and NH3 into the liquid phase. Pilot plant experimental data confirm the theoretical results. Further pilot plant experimental results obtained during on-off cycles of the stripping equipment demonstrate that, when the TFE unit is off, ammonia concentration in the digestate rises quickly, while, when the stripping equipment is turned on again, ammonia concentration drops down. On average, during the 180 days of pilot plant experimentation, 4.1 g N-NH4 per kg of sludge fed to the digester, i.e. 19.3 g N-NH4 per kg of total solids (TS) fed to the digester, are stripped from digestate and recovered as ammonium sulphate, demonstrating the feasibility of the proposed concept.

Deoxygenation of waste cooking oil and non-edible oil for the production of liquid hydrocarbon biofuels.

Deoxygenation of waste cooking vegetable oil and Jatropha curcas oil under nitrogen atmosphere was performed in batch and semi-batch experiments using CaO and treated hydrotalcite (MG70) as catalysts at 400 °C. In batch conditions a single liquid fraction (with yields greater than 80 wt.%) was produced containing a high proportion of hydrocarbons (83%). In semi-batch conditions two liquid fractions (separated by a distillation step) were obtained: a light fraction and an intermediate fraction containing amounts of hydrocarbons between 72-80% and 85-88% respectively. In order to assess the possible use of the liquid products as alternative fuels a complete chemical characterization and measurement of their properties were carried out.

Effects of adenosine-receptor agonists on renin release in anaesthetized rats.

OBJECTIVE: To investigate the effects of the interaction between adenosine receptors and renal nerves on renin release. MATERIALS AND METHODS: The effects on renin secretion of A1 (2-chloro-N6-cyclopentiladenosine) and A2 (2-hexynil-5'-N-ethyl-carboxamido-adenosine) adenosine-receptor agonists were studied in two groups of anaesthetized rats, each with one kidney surgically denervated. Arterial blood pressure and the renal blood flow of innervated and denervated kidneys were continuously recorded. Cannulae were inserted into both renal veins through femoral veins. After 1h of rest, A1 and A2 agonists were intravenously infused for 30 min in the two groups of rats. Plasma renin activity was measured by radioimmunoassay in blood samples drawn simultaneously from both renal veins and the femoral artery before and after the drug infusion. RESULTS: Infusions of A1 and A2 agonists produced comparable hypotensive effects. During A1 agonist administration, the heart rate decreased significantly, but it did not change after A2 agonist treatment. Renal blood flow was reduced by administration of the A1 agonist in both kidneys, while A2 agonist administration significantly reduced the renal blood flow of the innervated kidney only. The veno-arterial difference in plasma renin activity decreased after the A1 agonist infusion in both kidneys, but after the A2 agonist infusion it increased significantly in the innervated kidney only. CONCLUSIONS: Renal nerves do not influence the inhibition of renin release mediated by A1 adenosine receptors. In vivo, A2-receptor agonist administration can stimulate renin release only in the presence of intact renal nerves.

Role of the renal nerves in the control of renin synthesis during different sodium intakes in the rat.

OBJECTIVE: The aim of this study was to evaluate the role of the renal nerves in the regulation of renin synthesis in normotensive rats at different sodium balance. METHODS: Forty-eight male Sprague-Dawley rats were divided in six experimental groups, combining three diets at different NaCl content (normal 0.4%, low 0.04% or high 4.0%), and the surgical, bilateral renal denervation or the sham procedure. After 7 days of dietary treatment, all rats were sacrificed and plasma renin activity (PRA) was measured. Renin messenger RNA (mRNA) levels in the renal cortex were determined by semiquantitative polymerase chain reaction. RESULTS: PRA was higher in animals fed the low sodium diet compared with those at standard diet, while it was lower in animals fed the high sodium diet. Renal denervation decreased PRA in normal and low sodium groups, while it did not alter the PRA values in the high sodium group. Renin gene expression significantly increased in rats fed with the low sodium diet compared with the standard diet group, and significantly decreased in rats fed the high sodium diet Renal denervation significantly reduced renin mRNA levels in rats receiving the low sodium diet, but did not produce any significant change in normal or high-sodium groups. CONCLUSION: The activation of renin gene expression during sodium depletion in rats is dependent on the presence of the renal nerves, while the suppression of renin gene expression during a sodium load seems to be due to the macula densa mechanism alone.

Effects of adenosine receptor agonists on renal function in anaesthetized rats.

OBJECTIVES: To investigate the effects of the interaction between adenosine receptors and renal nerves on urinary sodium excretion and glomerular filtration rate. METHODS AND DESIGN: The effects on water and sodium excretion and glomerular filtration rate of A1 [2-chloro-N6-cyclopentyl-adenosine (CCPA)] and A2 [2-hesinyl-5'-N-ethyl-carboxamido-adenosine (2HE-NECA)] adenosine agonists were studied in anaesthetized rats with one kidney surgically denervated. Arterial blood pressure, heart rate and rate of urine flow from each kidney were continuously recorded; inulin clearance was used as an index of glomerular filtration rate. The experiments were performed with three groups of rats, into which, after a control period of 20 min, CCPA, 2HE-NECA or vehicle was infused for two subsequent 20 min periods. RESULT: During infusion of CCPA, the slight decrease in arterial pressure was associated with a transient decrease in glomerular filtration rate and marked long-lasting decreases in heart rate, water and sodium excretion and fractional sodium excretion. The response of the innervated kidney was similar to the response of the denervated kidney. Infusion of 2HE-NECA caused decreases in arterial pressure, glomerular filtration rate and excretion of water and sodium associated with an increase in heart rate. The reduction of water and sodium excretion from the innervated kidney was larger than that from the denervated kidney. CONCLUSIONS: Activation both of A1 and of A2 receptor causes a reduction in urinary water and sodium excretion. The renal response to activation of A2 receptors is enhanced by the presence of renal nerves, whereas the response to activation of A1 receptors is not influenced by renal nerves.

Angiotensin II modulates calponin gene expression in rat vascular smooth muscle cells in vivo.

OBJECTIVES: It has been shown that angiotensin II (Ang II) induces the expression of calponin, a 34 kD actin-binding protein, in vascular smooth muscle cells in vitro. The aim of this study was to investigate whether Ang II can modulate calponin gene expression in rat aorta in vivo. DESIGN: Aortic calponin gene expression was studied after chronic exogenous Ang II administration and in Goldblatt hypertension. METHODS: To investigate the effect of Ang II administration, Sprague Dawley rats were treated for 6 days with a continuous infusion of Ang II (200 ng/kg per min) or saline by osmotic minipumps. The effect of endogenous Ang II on aortic calponin mRNA expression was studied in Goldblatt hypertensive rats with (2K1C model), or without (1K1C model) activation of the renin-angiotensin system. In particular, calponin gene expression in 2K1C rats was studied both at 1 week (2K1C-HR, high renin) and 4 weeks after the onset of hypertension, when plasma renin activity (PRA) was returned to normal values (2K1C-NR, normal renin). Systolic blood pressure (SBP) was measured twice a week. At the end of the experimental period, PRA was measured by radioimmunoassay, and aortic calponin gene expression was measured by Northern hybridization. RESULTS: SBP was significantly higher (P < 0.01), whereas PRA was suppressed (P < 0.01), in Ang II versus saline-treated rats. Northern hybridization showed that the aortic calponin gene expression significantly increased (2.5-fold) in Ang II-treated rats (P = 0.01). In Goldblatt hypertensive rats, SBP was significantly higher in 2K1C-HR (P < 0.01), 2K1C-NR (P < 0.01) and 1K1C (P < 0.01) rats compared with the corresponding sham-treated rats. Activation of the renin-angiotensin system was present only in 2K1C-HR rats (P < 0.01), and Northern analysis showed that aortic calponin mRNA expression was significantly increased (2.2-fold) in this group of rats only (P < 0.01). CONCLUSIONS: Our data demonstrate that both exogenous and endogenous Ang II increase calponin gene expression in aortic smooth muscle cells, independently of the hemodynamic effect of Ang II.

Effects of erythropoietin administration on blood pressure and urinary albumin excretion in rats.

The effects of recombinant human erythropoietin (rHuEPO) administration on blood pressure and urinary albumin excretion were studied in normotensive Wistar-Kyoto rats (WKY), in spontaneously hypertensive rats (SHR), and in SHR rats treated with an angiotensin converting enzyme inhibitor (SHR-ACEi). Rats were housed in metabolic cages and treated with rHuEPO (150 U/kg body weight [bw] three times a week) for 6 weeks. Control animals received the vehicle only (0.25 mL of physiological saline). An angiotensin converting enzyme inhibitor was administered in the drinking water for 6 weeks (spirapril 5 mg/kg bw). Systolic blood pressure (SBP), and 24 h urinary albumin excretion (UAE) were measured once a week. No significant differences in SBP were observed between rHuEPO and vehicle-treated normotensive animals at the end of the treatment (171.9 +/- 4.9 v 172.1 +/- 5.6 mm Hg, respectively). After 6 weeks, SBP was significantly higher in SHR and SHR-ACEi groups treated with rHuEPO than in control groups (239.8 +/- 7.3 and 243.0 +/- 7.3 mm Hg v 218.1 +/- 6.0 and 187.9 +/- 4.6 mm Hg, respectively); UAE was significantly higher in groups treated with rHuEPO than in control groups (WKY: 265.9 +/- 19.5 v 127.0 +/- 12.3 microg/100 g bw, SHR: 1668.4 +/- 564.6 v 234.8 +/- 22.9 microg/100 g bw, and SHR-ACEi: 1522.7 +/- 448.3 v 143.0 +/- 18.9 microg/100 g bw, respectively). We concluded that erythropoietin treatment causes an increase in arterial pressure in SHR only, and an increase in UAE in both normotensive and hypertensive rats. The albuminuric effect was not entirely dependent on increased blood pressure. The treatment with an angiotensin converting enzyme inhibitor did not modify either the proteinuric or the pressor effects.

Behavioural stress blunts the creatinine clearance increase induced by a protein load in healthy subjects.

BACKGROUND: The aim of this study was to investigate how behavioural states related to different levels of stress affected the increments of glomerular filtration rate induced by an acute protein load. METHODS: Thirteen healthy subjects were enrolled. Each subject was studied from 9:00 h to 15:00 h on two consecutive days. In random order, after a protein meal (1.2 g/kg b.w. of protein), each subject was required to remain in a relaxing, sitting position (resting period, R), or to solve graphical and mathematical problems (behavioural stress period, S). Mean blood pressure (MBP) and heart rate (HR) were monitored by an ambulatory blood pressure device. Urine samples collected in each period were used to measure glomerular filtration rate (GFR, creatinine clearance) and urinary sodium excretion (UNa+V). RESULTS: Significant decreases in MBP and HR were observed during the resting period after the protein load, which significantly increased GFR. There was also a large increase of UNa+V. During S, the GFR changes were no longer seen whereas the increse of UNa+V was maintained. HR and MBP did not change compared to the prestimulus period. CONCLUSIONS: We conclude that in healthy subjects behavioural stress can blunt the increase in GFR that follows a protein load, presumably by neuro-humoral activated mechanisms. In our experimental conditions, behavioural stress did not affect UNa+V.

[The surgery of the tip of the nose]. / La chirurgia della punta nasale.

Surgery of the nasal tip has stimulated the creation of more surgical techniques than any other aspect of rhinoplastic surgery, to achieve an improved shape that seems natural while enhancing the balance and harmony of the face. The region described as tip of the nose is extremely varied from person to person, because of the different shape of its anatomical structures. For that reason to obtain a good result is necessary for the surgeon the perfect knowledge of the anatomy, the acquisition of surgical concepts and technical skill. The purpose of this paper is to describe the anatomy, the surgical technique and the principal method to correct the most common defects of the nasal tip; some of these proposed by many Authors are also discussed critically. Concerning the anatomy, the Authors describe the upper and the lower lateral cartilages, the lateral and medial crura of the alar cartilages, that form the "dome", the sesamoid complex: smaller cartilage that support the lateral crus, the septum cartilage, their ligaments and the maxillary spine. Are also exposed some concepts regarding the weak triangle of Converse and, in general, the soft tissues of the nasal tip. They also described some basilar incisions to approach the tip cartilage: marginal, intercartilaginous, intracartilaginous and transfixion. This surgical techniques allow to modified the cartilages that can be corrected in different manner. Some of these modifications concerning alar cartilages, septal cartilage, area of dome cartilage, and the most common techniques to operated on it, eversion and luxation, are also exposed. The last part of the paper concerning: a) the exposition of some anesthetical problems and their surgical approach; b) the description and discussion of some surgical techniques proposed in the literature by many Authors. Regarding the most common necessities to modified the nasal tip we include: a) to change the tip projection: in its two opposite directions, increasing and decreasing, where the first purpose is one of the most difficult objectives in tip surgery, using the medial cruras or in more difficult cases a colummellar strut; b) to reduce tip fullness, that normally requires a partial resection and/or a weakening of the lateral crura; c) to alter tip rotation: normally to obtain a upward, rarely for a down ward rotation to increase the length of the nose. In this case all these modifications are described following the theoretical concept of tripod, where the nasal tip is considered mechanically as a tripod with a lower leg represented by the medial crura and the two upper legs of the two lateral cruras.

[Septorhinoplasty in childhood]. / La rinosettoplastica in età pediatrica.

Septorhinoplasty plays an important role in childhood, particularly from the functional point of view. In fact, normal nasal respiration makes it possible to develop physical harmony throughout the entire body, particularly within the facial area. Nasal respiration serves as a defense mechanism, filtering air, thus relieving the lower respiratory tract of some work during the episodes of upper aero-digestive tract infection and inflammation so typical of childhood and early adolescence. The surgical indications should consider the central points in nasal surgery in childhood: there must be marked functional compromise; the aesthetic defect, if present, must be highly evident; the surgical treatment must be as limited and focused as possible as to prevent interfering with subsequent development of the nose, paranasal sinuses and facial structures. In those cases where the above conditions are not found, it is advisable to postpone surgery until the child has reached 16 years of age, when the development of the nasal and facial skeleton has been completed.

[Complications of rhinoplasty]. / Complicanze della rinoplastica.

For an operation as technically demanding as rhinoplasty, surprisingly few studies have examined the results of this procedure. A retrospective study was, therefore, made of 5470 patients who had undergone rhinoplasty, performed by different surgeons, from 1970 to 1989. The patients were followed up for a minimum of one year. As for all forms of surgery, aspecific complications such as infections, hemorrhage and side-effects from anesthesia will occasionally occur but, fortunately, such cases are quite rare. The specific classification included both early and late complications. Post-rhinoplasty failures may be estimated at approximately 28% of all cases; this figure taking into account typical deformities, both minor and severe, as well as functional sequelae and patient dissatisfaction. Approximately 4% have required secondary procedures. Some causes for failure derive from patient characteristics; for example, the importance and complexity of initial deformity are, of course, partly responsible, particularly after trauma. The skin quality (i.e. thickness, or whether it is fatty or loose) also affects the results. Furthermore, uncontrollable factors inherent to healing (i.e. excessive scar contraction in the intranasal area, connective tissue hyperplasia, particularly at the tip, and periosteal proliferation either to the osteotomy site or over the nasal dorsum) can all lead to residual deformities. Nevertheless, most failures can be attributed the operator. The commonest mistakes are linked to cartilaginous dorsum and nasal tip (approx. 22%). There are several polymorphic deformities the main sites of which should be known well in order to prevent, or at least reduce, such risks.

[Anterior craniofacial resection in the treatment of malignant nasal-paranasal sinus tumors with intracranial extension]. / La resezione cranio-facciale anteriore nel trattamento dei tumori maligni rino-sinusali ad estensione endocranica.

Nasal and paranasal sinus tumors extending through the cribriform plate to the overlying dura of the frontal lobe can be successfully treated by anterior craniofacial resection. During the period from 1986 to 1990, 14 patients (11 males, 3 females, age 18-67) with nasal/paranasal tumors extended to the nasal basis underwent craniofacial resection. From a histological point of view these patients were classified as follows: --8 adenocarcinomas --2 squamous cell carcinomas --2 esthesioneuroblastomas --1 cylindroma --1 haemangiopericytoma. In 6 of the 14 patients post-operative complications were encountered, 3 being resolved. Radical surgery was realised in 12 cases; post-operative radiotherapy was performed in 7. No contraindications were found because of previous chemo- and/or radiotherapy, even if it had been performed as treatment. Four of the patients died because of recurrences between the 6th and 20th month after surgery; 5 patients (all adenocarcinoma subjects) are disease-free respectively 8, 16, 17, 22 and 24 months after surgery.

[Fine needle biopsy in the preoperative diagnosis of parotid tumors]. / Validità dell'agobiopsia ad ago fine nella diagnostica preoperatoria delle tumefazioni parotidee.

Fine-needle aspiration biopsy is of particular interest in the parotid sites because, here, pathology with different treatments and prognosis manifest themself in the same way. The preoperative diagnosis of neoplasm is often problematic. As is known, this is correlated to several factors including histology, clinical and instrumental semiology. The instrumental image techniques (sialography, thermography, scintigraphy, ultrasound diagnosis, tac sialo-tac) give information as to size and location of the mass in question. Only rarely does it give any indication of whether the mass is malignant or benign. The authors systematically studied 386 parotid tumors. The method utilises a traditional technique (needle n. 12/2 gauge 1/4) and microscope examination with immediate dyeing to verify the correctness of the sample. 352 cases underwent surgery with subsequent histological verification. The results demonstrated a generical concordance of cytology and histology in the diagnosis of malignancy equal to 95%. The concordance of exact histology was 91%. The discordance regards, above all, the malignant neoplasm and particularly the mucoepidermoide and the adenoid cystic carcinoma. Fine needle aspiration demonstrates absolute specificity in the differential diagnosis between parotid and extraparotid pathology.