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Biomedical subjects

C Daniele

Publications and source records attributed to C Daniele.

At least 19 recordsLinked to original sources
PubMed1998

Progression of choroidal atrophy in acute posterior multifocal placoid pigment epitheliopathy.

Acute posterior multifocal placoid pigment epitheliopathy is a non-granulomatous chorioretinitis of uncertain origin that occurs in healthy young adults. The prevailing opinion is that the disease has a good long-term prognosis for visual acuity because it is self-limiting and chorioretinal scars do not enlarge with time. A middle-aged adult male who had acute posterior multifocal placoid pigment epitheliopathy in one eye has been followed for 22 years. After apparent clinical healing of the placoid epithelial lesions, widespread severe choroidal atrophy with visual loss occurred and progressed over years without interruption. To our knowledge this is the second report of progressive deterioration of a supposedly self-limiting chorioretinal disease.

Acute Disease↗
PubMed1997

A statistical approach to the quantitative comparison of pulsatile flow in vitro data of prosthetic heart valve testing.

BACKGROUND AND AIMS OF THE STUDY: In vitro evaluation and animal testing are fundamental steps in the assessment of prosthetic heart valves before their use in clinical practice. Valve testing under pulsatile conditions is the best in vitro simulation of cardiac valve function, and the ensuing results should support the surgeon's decision concerning the time of valve replacement. However, limits in hydraulic reproduction of cardiac function and differences in protocol implementation of in vitro testing lead to difficulties in obtaining reliable and comparable results. Debate among researchers and standardizing bodies about discrepancies in results becomes critical in light of the European CE certification of implantable medical devices. An interlaboratory environment has been created at the Biomedical Engineering unit of the Istituto Superiore di Sanita in Rome, which uses differing test apparatus to evaluate prosthetic heart valves in vitro, in order to define significant measurement parameters and procedures that produce comparative data. METHODS: Two prosthetic valves-a tilting disc and a bileaflet valve-each sized 29 mm, were tested in the aortic position on two different pulse duplicators (PDs), namely the Dynatek MP1 and a system developed at the University of Sheffield. The common protocol adopted was the FDA Interlaboratory Comparison Testing Protocol. Original software was used to manage all test phases, thus minimizing operator-dependent variability in both systems and imposing strict control of experimental conditions. Statistical analysis performed on the data followed two approaches: (i) separate fitting of the two regression equations of pressure drop-flow rate relationship obtained for each valve on both PDs, and (ii) application of a multiple regression model, to fit a single regression equation of pressure drop-flow rate relationship, using data obtained from both PDs for each valve. In addition, an additional independent (dummy) variable was introduced. RESULTS AND CONCLUSIONS: Using this approach, the valve parameter range was obtained and, by imposing strict control of the experimental set-up, the coincidence of the two valve power laws, estimated by each of the two PDs, was studied.

Heart Valve Prosthesis↗
PubMed1997

19 mm sized bileaflet valve prostheses' flow field investigated by bidimensional laser Doppler anemometry (part I: velocity profiles).

The investigation of the flow field downstream of a cardiac valve prosthesis is a well established task. In particular turbulence generation is of interest if damage to blood constituents is to be assessed. Several prosthetic valve flow studies are available in literature but they generally concern large-sized prostheses. The FDA draft guidance requires the study of the maximum Reynolds number conditions for a cardiac valve model to assess the worst case in turbulence by choosing both the minimum valve diameter and a high cardiac output value as protocol set up. Within the framework of a national research project regarding the characterization of cardiovascular endoprostheses, the Laboratory of Biomedical Engineering is currently conducting an in-depth study of turbulence generated downstream of bileaflet cardiac valves. Four models of 19 mm sized bileaflet valve prostheses, namely St Jude Medical HP Edwards Tekna, Sorin Bicarbon, and CarboMedics, were studied in aortic position. The prostheses were selected for the nominal annulus diameter reported by the manufacturers without any assessment of the valve sizing method. The hemodynamic function was investigated using a bidimensional LDA system. Results concern velocity profiles during the peak flow systolic phase, at high cardiac output regime, highlighting the different flow field features downstream of the four small-sized cardiac valves.

Aortic Valve↗
PubMed1997

19 mm sized bileaflet valve prostheses' flow field investigated by bidimensional laser Doppler anemometry (part II: maximum turbulent shear stresses)

The investigation of the flow field generated by cardiac valve prostheses is a necessary task to gain knowledge on the possible relationship between turbulence-derived stresses and the hemolytic and thrombogenic complications in patients after valve replacement. The study of turbulence flows downstream of cardiac prostheses, in literature, especially concerns large-sized prostheses with a variable flow regime from very low up to 6 L/min. The Food and Drug Administration draft guidance requires the study of the minimum prosthetic size at a high cardiac output to reach the maximum Reynolds number conditions. Within the framework of a national research project regarding the characterization of cardiovascular endoprostheses, an in-depth study of turbulence generated downstream of bileaflet cardiac valves is currently under way at the Laboratory of Biomedical Engineering of the Istituto Superiore di Sanita. Four models of 19 mm bileaflet valve prostheses were used: St Jude Medical HP, Edwards Tekna, Sorin Bicarbon, and CarboMedics. The prostheses were selected for the nominal Tissue Annulus Diameter as reported by manufacturers without any assessment of valve sizing method, and were mounted in aortic position. The aortic geometry was scaled for 19 mm prostheses using angiographic data. The turbulence-derived shear stresses were investigated very close to the valve (0.35 D0), using a bidimensional Laser Doppler anemometry system and applying the Principal Stress Analysis. Results concern typical turbulence quantities during a 50 ms window at peak flow in the systolic phase. Conclusions are drawn regarding the turbulence associated to valve design features, as well as the possible damage to blood constituents.

Aortic Valve↗
PubMed1996

Pattern dystrophies of the retinal pigment epithelium.

Pattern dystrophies of the retinal pigment epithelium are infrequent fundus abnormalities arranged in various patterns of dots, lines and branches. The basic lesion appears to be yellow deposits of abnormal lipofuscin accumulated within degenerated retinal pigment epithelium cells. Examinations were carried out on two families who had developed different patterned alterations in the retinal pigment epithelium. The proband of family 1 had diffuse changes associated with equatorial folds. One sister had a macular alteration. A daughter was normal; a son had bilateral atrophy of the temporal retinal pigment epithelium. The proband of family 2 had bilateral, symmetrical retinal pigment epithelium lesions that simulated fundus flavimaculatus. His first daughter had a central lesion in her right eye. The second daughter, a peripapillary crescent of hyperpigmentation in her right eye, and circumpapillary chorioretinal atrophy associated with foveolar abnormalities in the left. This report provides further evidence that variable types of pattern dystrophy can occur within a single family pedigree and support the current opinion that all forms of pattern dystrophies are variants of a single pathogenic mechanism.

Adult↗
PubMed1996

[Orthotopic neobladder in women].

In women undergoing radical cystectomy for bladder cancer, orthotopic bladder reconstruction is now a viable alternative to urinary diversion: preservation of the external urethral sphincter by sectioning the urethra 0.5-1 cm distally to the bladder neck allows maintenance of urinary continence without compromising cancer control. 12 cases of bladder reconstruction in women operated on from 1986 to 1995 are presented here. A personal technique for the creation of an ileal neobladder is described: the use of staplers for detubularization of the ileum significantly reduces the operating time ("simplified ileal bladder"). Other important points of technique are as follows: 1. Careful preparation of the bladder neck and proximal urethra, staying above the pubo-urethral ligaments that must be preserved as the distal landmark of dissection; 2. "Nerve-sparing" isolation of the posterolateral wall of the bladder from the vagina; 3. Careful positioning of the pouch in the true pelvis, in order to avoid posterior prolapse of the neobladder. So far, results of bladder reconstruction in this series of patients are encouraging, both from a functional and oncological standpoint.

Cystectomy↗
PubMed1995

Evaluation of tilting disc valves after fatigue life testing: preliminary results within a comparison program.

A fatigue life test, by accelerating the beat rate, simulates several years of virtual life of a prosthetic heart valve in a short period of time. The correlation between the in vivo life of a valve and in vitro testing expectations is as yet not well established, but reproducible test conditions yield precious information about wear and failure. The paper reports a qualitative analysis of mechanical valve wear as part of a comparison program designed to investigate the significance of fatigue testing with the ultimate aim of defining standard guidelines for these type of tests. Two tilting disc valves (29 mm) were subjected to 16 years of fatigue life simulated by means of a Rowan Ash fatigue tester (accelerated rate of 1,200 bpm). Fatigue-induced effects on valve disc and ring surfaces were observed under a monitor microscope to identify wear sites and patterns. A high speed cinematographic system was used to investigate the mechanisms responsible for the wear (wear modes). Valve closure was inspected at a 6,000 frame/s rate. Because of disc rotation during the tilting movement, the points of contact between disc and ring are distributed all around the disc edge but focally on the ring. On both sides of the disc, the surfaces present ring-like concentric grooves. After 16 years of fatigue life the valves showed neither severe wear nor alteration of their fluidodynamic behavior in the pulsatile flow test.

Biomechanical Phenomena↗
PubMed1995

Fundus abnormalities in Cushing's disease: a preliminary report.

Three patients, 2 males and 1 female, with intrasellar, hypersecretive pituitary adenoma were studied. Blood hypertension was present in all and hyperglycemia in 2 (1 male, 1 female). None had neurological signs of compression of the optic disk or chiasma. One patient showed bilateral circumpapillary and multiple retinal pigment epithelium (RPE) detachment with pooling defects and intraretinal leakage from small retinal arterioles. Another had loss of foveolar, macular and retinal reflexes in the right eye; negligible RPE changes became visible with fluorescein angiography. The third, who had developed malignant hypertension, manifested bilateral hypertensive neuroretinopathy and papilledema. The simultaneous improvement of general and ocular symptoms after removal of the pituitary tumor makes a causal relationship possible and even very likely, between the underlying disorder and fundus abnormalities.

Adenoma↗
PubMed1995

Association of peripapillary scars with lesions characteristic of multiple evanescent white-dot syndrome.

Multiple evanescent white-dot syndrome, acute idiopathic blind-spot enlargement syndrome and multifocal choroiditis (pseudo-ocular histoplasmosis syndrome) are fundus diseases of unknown etiology. A single etiological agent or group of similar agents is thought to be responsible for these relatively rare manifestations. A 35-year-old male with associated symptoms of enlargement of the blind spot, evanescent white-dot syndrome and presumed ocular histoplasmosis is described. The association of these highly differentiated fundus abnormalities strengthens the hypothesis of an etiological or pathological linkage within phenotypically variable clinical forms.

Acute Disease↗
PubMed1995

Aggravation of laser-treated diabetic cystoid macular edema after prolonged flight: a case report.

A 62-year-old diabetic woman with pan-retinal laser treatment for non-proliferative, bilateral diabetic retinopathy and cystoid macular edema (CME) demonstrated an acute exacerbation of CME after 42 h of prolonged flight in commercial pressurized aircraft. When travelling by air, vital sensory functions of the human body are affected by a variety of disturbing factors. The most important of these--altitude-related oxygen deficiency--is compensated for by homeostatic mechanisms in healthy subjects. However, even with normal oxygen tension, the diabetic retina is hypoxic because the vascular response to oxygen variation is altered. Increased tissue demand for oxygen, owing to decreased ability of the circulating blood to release oxygen, cannot be met. In our patient, the aggravated CME appeared to result from hemodynamic changes induced by flight. In particular, the prolonged environmental oxygen deficiency may have exacerbated the retinal hypoxia leading to acute, vascular decompensation and dramatic plasma leakage with visual loss.

Aerospace Medicine↗
PubMed1994

Changes in human epithelial kidney cells induced by nordihydroguaiaretic acid in vitro.

Some chemical agents induce kidney cystic changes in vivo comparable to human multicystic kidney disease. The biochemical aspects of human tubular cells were analysed by in vitro culture in the presence of nordihydroguaiaretic acid (NDGA). The uptake of 3H-thymidine in cultured cells in the presence of NDGA was comparable with control cultures, while 3H-hydroxyproline incorporation produced elevated values. The results suggest that NDGA in vitro induces modifications which may be related only to the synthesis of basement membrane components.

Cell Division↗
PubMed1993

[First impressions regarding the use of expandable esophageal prosthesis].

The authors report their views on the treatment of unoperable neoplastic esophago-gastric stenoses with Nitinol prostheses. Despite a number of advantages (reduced trauma, greater tolerability) in relation to plastic prostheses, the paper highlights some problems (difficulty of unfastening, incomplete opening) which may be eliminated by improved materials.

Aged↗
PubMed1992

[Preliminary experience with the Storz Modulith SL 20 lithotriptor in reno-ureteral lithiasis].

The authors report their initial results in ESWL of urinary calculi with the Storz Modulith SL 20 lithotriptor, a multipurpose device for both urinary and biliary stone treatment. During 176 sessions, a total of 144 cases (81 renal and 63 ureteral) were treated and then, followed up. The over-all rate free of stones was 86.8% (90.1% for kidney and for ureteral stones). The treatment rate was 1.23 per patient. Auxiliary procedures before ESWL were performed in 7.9% of the sessions: insertion of "double-J" stent or nephrostomy tube; all ureteral stones received "in situ" treatment. Mean number of shock waves per session was 1836.1 (range 300-3020). The maximum voltage on the average reached was 17.1 kv. Sedo-analgesia by Diazepam and Ketoprofen was given in 75% of the cases. No serious complications were observed. The experience with this machine is discussed in regard to performance; the advantages of its fluoroscopy and ultrasound guided system of focusing are stressed.

Adolescent↗
PubMed1991

Prosthetic heart valve evaluation in vitro: critical aspects of data comparability.

The technology of heart valve substitution has considerably improved in the last few years, but its reliability after implantation is still not good enough, hence the need to study new valve design and improve quality testing. Different pulse duplicators are used for heart valve testing, but the results depend very much on the system adopted and the measurement protocol. Tests on two pulse duplicators currently used at the Biomedical Engineering Laboratory at the Istituto Superiore di Sanità, Rome, are reported here. The most significant parameters for valve evaluation were measured following each system's own protocol. Attention was focused on vascular load tuning when setting up the system and on the relationship between drive unit flow waveform and valve regurgitation and energy loss measurements. Standardization criteria must be defined in order to ensure the reliable comparability of in vitro testing results.

Coronary Circulation↗
PubMed1990

[Diagnostic screening of varicocele: role of echography and Doppler examination in our experience with 216 cases of primary varicocele].

We compared two non-invasive methods to evaluate primary varicoceles: ultrasonography and Doppler examination. We submitted to ultrasonography and Doppler 216 patients, 147 of them were treated by sclerotherapy and 69 by surgery. All ultrasonographic studies were performed by means of a real-time equipment (7.5 Mhz transducer), while Doppler examination was performed with continuous wave equipment. Ultrasonographic findings are reliable for testicular morphology. Doppler examination is useful to evaluate reversed flow. In 4.1% of cases ultrasonography did not agree with the Doppler examination.

Humans↗
PubMed1990

[Staplers in bladder sutures].

Staplers are still little used for suturing a cystotomy. The basic reason for this reluctance is the inadvisability of using non-absorbable material in the lumen of the urinary tract, as this may be the nucleus for the formation of stones. It must be remembered, however, that a correct suture of a cystotomy should be carried out in two layers: one internal mucous layer, consisting of a continuous suture of absorbable material, and a more superficial suture of the margins of the vesical detrusor. The latter can be performed with a linear stapler, as it is completely outside the mucous layer. More recently, linear staplers with absorbable staples have appeared on the market, by which cystotomy sutures can be performed in a single layer.

Evaluation Studies as Topic↗