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Biomedical subjects

A Stella

Publications and source records attributed to A Stella.

At least 181 records · Page 10Linked to original sources
PubMed1976

Neural factors contributing to renin release during reduction in renal perfusion pressure and blood flow in cats.

1. The participation of neural mechanisms in mediating the renin release induced by reduction of renal perfusion pressure was explored in anaesthetized cats by comparing renin release from the two kidneys, one acutely denervated and the other intact. 2. Suprarenal aortic stenosis of 10 min duration reduced renal perfusion pressure to 50 mmHg and halved blood flow to both kidneys, but cause a greater release of renin from the innervated kidney than from the contralateral denervated one (increments of 72 +/- 17 and 29 +/-20 pmol/min respectively). 3. A study of the time-course of the response during aortic stenosis of 30 min duration showed early release of renin from the innervated kidney at a time (5 min) when little release occurred from the denervated one. In later samplings (15 and 30 min) the response of the innervated kidney levelled out at somewhat lower values, and that of the denervated organ progressively increased, but remained smaller than on the side with intact nerves. 4. There was no parallelism between renin release and renal vasomotor changes induced by aortic stenosis, as vasomotor changes were equal in the two kidneys and remained constant from beginning to end of stenosis. It is concluded that a significant part of the renin release induced by aortic stenosis is dependent on neural mechanisms: the neural differs from the non-neural component in being of more rapid onset and probably of shorter duration.

Animals↗
PubMed1976

Role of the renal nerves in renin release during suprarenal aortic stenosis in cats.

1. Renin release from an intact, innervated kidney and from the contralateral denervated kidney was measured before and during a period of suprarenal aortic stenosis. 2. Aortic stenosis of 10 min duration reduced renal perfusion pressure to 50 mmHg and increased renin release from both kidneys, but the response from the innervated kidney was greater. 3. A study of the time-course of the response during 30 min of aortic stenosis showed that the difference in rate of renin release between the innervated and the denervated kidney is greatest during the first few minutes of aortic stenosis.

Animals↗
PubMed1976

Haemodynamic responses and renin release during stimulation of afferent renal nerves in the cat.

1. Experiments were done on anaesthetized cats to study the effect of electrical stimulation of afferent renal nerves on the circulatory system and on the release of renin from the kidney. 2. Stimulation of afferent renal nerves over a wide range of parameters consistently elicited an increase in arterial pressure and heart rate. This response was still present in paralysed animals and was not accompanied by changes in respiration or in sympathetic autonomic activity usually associated with painful stimulation. Mesenteric and iliac vasoconstriction was observed concomitantly with the increase in arterial pressure. 3. Release of renin from the contralateral innervated kidney was not significantly changed by stimulation of afferent renal nerves. 4. The existence of renal vascular mechanoreceptors was investigated by altering renal circulation. Stenosis of the renal artery or a marked reduction in renal perfusion pressure elicited an increase in arterial pressure while stenosis of the renal vein elicited a decrease in arterial pressure. These responses, however, were not affected by denervation of the kidney and were therefore interpreted as not being due to neural mechanisms. 5. The precise nature, location and physiological role of renal receptors involved in the cardiovascular responses observed during electrical stimulation of afferent renal nerves remain to be determined.

Animals↗
PubMed1975

Neural control of renin release.

1. Factors involved in the neural control of renin release have been reviewed. 2. Experimental evidence has been obtained that sympathetic stimulation releases renin from the kidney independently of local vasomotor changes. 3. The reflex control of renin release on postural change has been established. 4. The effect of diuretics on renin release has been studied and evidence of neural and non-neural mechanisms obtained. 5. The effect of suprarenal aortic stenosis has been studied; the findings suggest that renin release is in some way dependent on neural mechanisms. 6. The pathological significance of the neural control of renin release has been discussed.

Animals↗
PubMedDate not supplied

Fresh and cryopreserved arterial homografts: immunological and clinical results.

INTRODUCTION: This prospective study defined the immunological and clinical results after fresh and cryopreserved arterial homograft replacement due to graft infection. MATERIALS AND METHODS: Thirty patients who underwent ABO-compatible homograft transplantation were studied for anti-human leukocyte antigen (HLA): antibody production and CD3- and CD4- versus CD8-positive lymphocyte subsets. Nine patients (30%) received immunosuppressive treatment with cyclosporine (1 to 3 mg/kg/d). Immunological studies were performed preoperatively, and early (1, 3, 7 days) and late (1, 3, 6, 12, 24, 36, 48 months) during follow-up. Abdominal computed tomography scans were performed postoperatively at 1, 6, 12, 24, 36, and 48 months of follow-up. RESULTS: Preoperatively, antibodies were not detected. Postoperatively, a progressive increase in percent panel reactive antibodies was observed in all patients 1 month after the transplant. There were no difference between fresh and cryopreserved homografts. The antibody response among patients treated with cyclosporine was less pronounced and delayed. Recipient antibodies were directed against donor-specific antigens. During the immediate postoperative period (1, 3, 7 days) there was a slight increase in CD3- and CD4-positive T lymphocytes and a concomitant decrease in the CD8 subset. Later, CD3 and CD4 progressively decreased and the CD8 set increased. Clinically, no patients had signs of recurrent infection upon late follow-up. Four patients died (13%), but only one death was homograft-related (rupture of the graft). At 2-year follow-up, two patients showed stenotic lesions due to chronic rejection. Clinically, no differences were noted between fresh and cryopreserved homografts, or between patients treated with or without cyclosporine. CONCLUSIONS: Fresh and cryopreserved arterial homografts are immunogenic; they induce a strong anti-HLA antibody response, similar to chronic rejection.

ABO Blood-Group System↗
PubMedDate not supplied

Vascular tissue banking: state of the art.

INTRODUCTION: The cardiovascular homograft banks in Italy were set up in 1994 in Milan (Lombardia) and Treviso (Veneto) and in 2001 in Bologna, Emilia Romagna. In this study we briefly summarize the data from Emilia Romagna Cardiovascular Tissue Bank. MATERIAL AND METHODS: In Emilia Romagna, vascular homografts were harvested from brain-dead multiorgan donors (aged 15-55 years) by a dedicated vascular surgery team. All donors were virologically screened for human immunodeficiency virus (HIV), hepatitis B and C, Treponema pallidum, cytomegalovirus (CMV), and Toxoplasma. After transferring the vascular homografts to Emilia Romagna Cardiovascular Tissue Bank facilities, the arteries were prepared, classified (class III to I), and transferred to an antibiotic-containing solution under a laminar flow cabinet. After the decontamination, all homografts were cryopreserved and stored in the vapour phase of liquid nitrogen. Microbiological tests were performed in all phases of preparation. Samples were routinely taken from 1 vessel and formalin fixed for the histology. Bags with cryopreserved homografts were sent in dry ice to the hospitals when required and thawing protocol of the Bank was included. RESULTS AND CONCLUSIONS: From January 2002 to October 2004, 543 homografts from 125 heart-beating donors were harvested and transferred to Emilia Romagna Cardiovascular Tissue Bank. After preparation, 459 of 543 (85%) were cryopreserved and stored. Vascular homografts classified class I were discarded. Other criteria of rejection were: (1) positive serology, and (2) persistent positive microbiology after decontamination. From March 2002, 333 cryopreserved homografts were assigned to several vascular surgery departments in Italy. The assessment of 3-year activity of Emilia Romagna Cardiovascular Tissue Bank might be used as an indicator of the efficiency of selecting, cryopreserving, and allocating quality-controlled vascular homografts.

Adolescent↗
PubMedDate not supplied

Cryoactivation fails to augment plasma renin activity in the cat.

1. Active and cryoactivated renin (plasma renin) activity after incubation at -5 degrees C for 4 days, were measured in cat plasma sampled before and during the following procedures: suprarenal aortic stenosis, electrical stimulation of the pons and mild hypotensive haemorrhage. 2. Under all experimental conditions the values of plasma renin activity for both the activated and non-activated samples were similar. 3. The absence of a cryoactivatable aliquot of renin suggests that in cat plasma the inactive form of the enzyme either is actually absent or has a liability to the action of cold different than in other animal species.

Animals↗
PubMedDate not supplied

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.

Adult↗
PubMedDate not supplied

[Thoraco-abdominal aneurysms of type IV].

AIM OF THE STUDY: Aims of the study were: 1. to evaluate the results of surgical treatment of type IV thoraco-abdominal aneurysms (TAA), with relationship to other types, 2. to evaluate results obtained with an approach different from the traditional thoraco-phreno laparatomy, with specific attention to postoperative respiratory function. MATERIAL AND METHODS: We have retrospectively compared type IV TAA with all other types of thoraco-abdominal aneurysms electively treated between January 1st, 1994 and May 31st, 2003. Data on perioperative mortality, spinal cord ischemia and renal failure (both temporary and permanent) occurring in the first 30 postoperative days were considered. Protection from spinal cord ischemia was accomplished through liquor drainage and prostaglandin E1 (PGE1) infusion. When the aneurysm extension was limited to the celiac axis an extrapleuric access with removal of XI rib was performed. In this subgroup of patients we have considered postoperative recovery time of respiratory function (intubation time, number of days in intensive care unit, postoperative pulmonary complications) postoperative renal failure, perioperative mortality and morbidity. RESULTS: Seventy-eight TAA have been treated in the period of time of the study. Twenty cases were type IV TAA (25.6%) of which 2 due to chronic dissection. Cumulative postoperative mortality has been 19.2%. The single perioperative death in the group of type IV TAA (5%) occurred in post-operative day 15 for multiple organ failure. No spinal cord ischemia occurred in this group. Temporary renal failure occurred in 3 cases (15%) with one case requiring dialysis. In 10 cases (50%) an extrapleuric access with removal of XI rib was performed, with adequate control of the proximal aorta. Postoperative respiratory failure requiring and intubation time longer than 12 hours occurred in 2 cases (20%). In the remaining 8 cases the mean intubation time was 5.3 hours (range 4-8 hrs). Tracheostomy was not necessary in any case. Mean time of intensive care unit stay was 3.5 days (range 0-15 days). CONCLUSION: The appropriate treatment of type IV TAA leads to low mortality and morbidity with results similar to those of pararenal aneurysms rather than those of other TAA forms. Left extrapleuric access when feasible allows faster recovery of a normal respiratory function.

Adult↗
PubMedDate not supplied

Parietal inflammatory infiltrate in peripheral aneurysms of atherosclerotic origin.

Clinical and histological analyses were made of 18 consecutive cases of peripheral artery atherosclerotic aneurysms (PAAA) (common, deep femoral and popliteal arteries) and compared to a group of 10 specimens obtained from the atherosclerotic, non aneurysmal femoral arteries of 10 cadavers with similar characteristics to the 18 patients. Although neither the clinical nor the macroscopic morphological data indicated the presence of an inflammatory process in the PAAA, the histological examination revealed the presence of a considerable infiltrate (greater than 11 inflammatory cells/2116 microns2) in a surprisingly high percentage of cases (4 cases, 22.8%). In 5 other cases (27.7%) the presence of lymphomonoplasmonocytic cells, although less pronounced, was greater than normally seen in atherosclerotic arterial walls (greater than 4 and less than 11 inflammatory cells/2116 microns2). The median number of inflammatory cells present in the media and adventitia varied from 2.2 +/- 0.3 to 13.2 +/- 0.3 per 2116 microns2. These values are significantly different compared to the results of atherosclerotic arteries at the same level (P less than 0.001 Mann-Whitney's U test). These findings of lymphomonoplasmocytic infiltrates in the absence of other pathology, together with an analysis of the data in the literature, makes it possible to presume that the inflammation present is associated with atherosclerosis and is more common in aneurysmal rather than stenotic forms. The pathogenesis may be determined by immune reaction phenomena.

Aged↗