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Biomedical subjects

F Colombo

Publications and source records attributed to F Colombo.

At least 19 recordsLinked to original sources
PubMed1992

Errors introduced by tissue heterogeneity in estimation of local cerebral glucose utilization with current kinetic models of the [18F]fluorodeoxyglucose method.

The effects of tissue heterogeneity on the estimation of regional cerebral glucose utilization (rCMRglc) in normal humans with [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) were compared with respect to the various kinetic models of the [18F]FDG method. The kinetic models were conventional homogeneous tissue models of the [18F]FDG method, with (4K Model) and without (3K Model) a rate constant to account for an apparent loss of [18F]2-fluoro-2-deoxy-D-glucose-6-phosphate ([18F]FDG-6-P), and a tissue heterogeneity model (TH Model). When either of the kinetic models designed for homogeneous tissues was applied to heterogeneous tissues, estimates of the rate constant for efflux of [18F]FDG from the tissue (k2*) and of the rate constant for phosphorylation of [18F]FDG (k3*) decreased as the duration of the experimental period was increased. When the 4K Model was used, estimates of the rate constant for the apparent dephosphorylation of [18F]FDG-6-P (k4*) were significantly greater than zero and fell with increasing duration of the experimental period. Although the TH Model included no term to describe an apparent dephosphorylation of [18F]FDG-6-P, the fit of the TH Model to the time course of total tissue radioactivity was at least as good as and often better than the fit of the 4K Model in the 120-min period following the pulse of [18F]FDG. Hence, the high estimates of k4* found in PET studies of less than or equal to 120 min can be explained as the consequence of measuring radioactivity in a heterogeneous tissue and applying a model designed for a homogeneous tissue; there remains no evidence of significant dephosphorylation of [18F]FDG-6-P in this time period. Furthermore, use of the 4K Model led to an overestimation of rCMRglc; whole-brain glucose utilization calculated with the 4K Model was greater than 20% higher than values usually obtained in normal humans by the model-independent Kety-Schmidt technique. rCMRglc was accurately estimated by the TH Model and, in experimental periods sufficiently long to minimize the effects of tissue heterogeneity, also by the original 3K Model of the deoxyglucose method.

Adult↗
PubMed1992

Metabolic impairment in human amnesia: a PET study of memory networks.

Human amnesia is a clinical syndrome exhibiting the failure to recall past events and to learn new information. Its "pure" form, characterized by a selective impairment of long-term memory without any disorder of general intelligence or other cognitive functions, has been associated with lesions localized within Papez's circuit and some connected areas. Thus, amnesia could be due to a functional disconnection between components of this or other neural structures involved in long-term learning and retention. To test this hypothesis, we measured regional cerebral metabolism with 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET) in 11 patients with "pure" amnesia. A significant bilateral reduction in metabolism in a number of interconnected cerebral regions (hippocampal formation, thalamus, cingulate gyrus, and frontal basal cortex) was found in the amnesic patients in comparison with normal controls. The metabolic impairment did not correspond to alterations in structural anatomy as assessed by magnetic resonance imaging (MRI). These results are the first in vivo evidence for the role of a functional network as a basis of human memory.

Adult↗
PubMed1992

Prevalence and variability of orthostatic hypotension in the elderly. Results of the 'Italian study on blood pressure in the elderly (SPAA)'. The 'Gruppo di Studio Sulla Pressione Arteriosa nell'Anziano'.

The prevalence of orthostatic hypotension (OH) in an elderly outpatient population was assessed according to the most common criteria given in the literature. Short-term OH variability and relationships between OH and its known risk factors were also analysed. A sample of 3858 elderly outpatients aged 65 years or more was randomly recruited by 444 Italian general practitioners. The patients' blood pressure (BP) and heart rate were recorded in both lying and standing positions at two visits 7 days apart. Three definitions were used for the identification of OH: (1) a decrease in systolic BP greater than 20 mmHg (SOH); (2) a decrease in both systolic (greater than 20 mmHg) and diastolic (greater than 10 mmHg) BP (SDOH); (3) any decrease in systolic BP associated with symptoms (SyOH). Prevalence figures for SOH were 13.8% at the first and 12.6% at the second visit, and respectively 5.3 and 4.8% for SDOH, 14.1 and 11.8% for SyOH. All the criteria were met by less than 2% of subjects at each visit. The diagnosis of OH was confirmed at both visits in 36.3% of cases for SOH, in 25.7% for SDOH, and in 43.9% for SyOH. Each different OH definition identifies a population subgroup characterized by different sets of risk-factors. The presence and prevalence of OH is difficult to define because different people may be identified by the currently accepted criteria or by the same criterion over a short time.

Aged↗
PubMed1992

Venous surgery in erectile dysfunction: therapeutic strategy and results.

The therapeutic rationale of venous surgery is to create an effective obstacle to the pathologically increased venous outflow, determined by an intrinsic pathology of the cavernous bodies. In the last 15 years, many techniques have been proposed, and our therapeutic approach has evolved with our knowledge of penile haemodynamics. Up to October 1990, we performed 316 operations for the relief of impotence. In a 2-year follow-up our recurrence rates were as follows: DDV plus corporpexy (n = 50): 26% (n = 13); DDV plus crura plication (n = 34): 47% (n = 16); DDV plus collateral vein ligation (n = 48): 62.5% (n = 30).

Arterial Occlusive Diseases↗
PubMed1992

Prognostic significance of prostate-specific antigen in endocrine treatment for prostatic carcinoma.

We have studied the prognostic significance of prostate-specific antigen (PSA), monitored monthly, in 24 patients with prostatic cancer (5 D1, 19 D2) on endocrine therapy. The pretreatment levels of PSA were high in all patients (mean value 41 ng/ml). It was found that PSA levels at the end of the first and sixth months of treatment were reliable prognostic indicators. At the first month evaluation PSA had decreased more than 50% from the initial values in the 16 patients with stable disease, while it had decreased less than 50% in those with progressing disease. At the end of 6 months, patients with stable disease had PSA levels within the normal range, while 8 of the patients who had progressing disease had levels higher than 10 ng/ml. Respectively 6 and 2 patients had also had increases in PSA levels at 3 and 6 months before scintigraphic demonstration of increased bone metastases.

Aged↗
PubMed1992

Efficacy and tolerability of medium-term treatment with simvastatin in primary hypercholesterolaemia.

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, a new class of hypolipidaemic agents, have been recently shown to be effective in lowering both total and low-density lipoprotein (LDL)-cholesterol. In the present study 20 patients were treated with simvastatin for six months. Various dosing regimens of 10, 20, and 40 mg/day were employed. Administration of simvastatin 10 to 40 mg/day resulted in a 24.7 to 35.8% reduction in LDL-cholesterol levels and in a 19.5 to 26.9% decrease of total cholesterol levels. Moreover, simvastatin increased high-density lipoprotein-cholesterol and induced a decrease in plasma triglycerides. The side-effect profile was similar to other observations and included reversible transaminase elevations, myalgia and gastrointestinal complaints. From the present study simvastatin seems to be well tolerated in the short- to medium-term and to be effective; however, its long-term tolerability needs to be confirmed.

Adult↗
PubMed1992

Feasibility of a long-term low-sodium diet in mild hypertension.

The present study set out to assess the feasibility of long-term moderate dietary sodium restriction in patients with mild hypertension in general practice. After screening and a run-in phase of 6-8 weeks, a total of 77 previously undiagnosed mildly hypertensive patients were identified. Half of them were randomized to receive a few simple dietary instructions from their general practitioners in order to reduce salt usage; the others were randomized to receive no advice. The patients were followed up for 12 months with quarterly visits. A total of 56 patients (72.7%) completed the study, 26 on a low-sodium diet (LD) and 30 on their usual diet (UD). At each visit in the diet phase, patients provided 24h urine, which was analysed for volume and sodium concentration in order to assess their sodium intake. Blood pressure, heart the rate and body weight were recorded. The mean urinary sodium excretion for all diet phase visits overlapped in the two groups (177.0 +/- 32.9 vs. 169.3 +/- 49.4 mEq/24h respectively in the LD and UD groups). Nevertheless the mean systolic and diastolic blood pressures for all diet phase visits were significantly lower in the LD than in UD group (144.2 +/- 11.1/91.6 +/- 6.4 and 148.0 +/- 13.7/95.6 +/- 4.7 mmHg respectively, P less than 0.01). Our data suggest that it is not feasible at present to reduce sodium intake in mild hypertensives with simple and inexpensive dietary instructions, the only ones suitable for widespread application in general practice.

Adult↗
PubMed1992

[Impotence from the 70's through the 90's: 20 years of evolution of diagnosis and therapy].

The surgical treatment of vascular impotence has evolved as our understanding of the haemodynamics of erection advanced. In the early Seventies the direct revascularization techniques which create an anastomosis between an artery and the corpora cavernosa came to be so much in use that an era of so-called "pure arteriogenic impotence" seemed to be dawning. An arterial role in the pathogenesis of importance gained increasing support during that decade, as the use of a number of techniques for the diagnostic assessment of penile haemodynamics becomes widespread (Doppler ultrasound, determination of the penile-brachial index, selective hypogastric arteriography, penile radionuclide scan, penile plethysmography). Corpora cavernosa-direct revascularization techniques, such as the Epigastric-Corporal and Femoro-Corporal trans-Saphena anastomoses, were developed, the latter being proposed by Michal in 1973. By the late Seventies, however, most Authors had abandoned these techniques. Severe haemodynamic side-effects, such as uninterrupted intra-cavernous high pressure and attendant permanent tumescence of penis, were found to induce the microfibrosis of erectile tissues and the thrombosis at the site of the anastomosis. In this period, "venous leakage" became, with the advent of cavernosography, a recognized factor in the pathogenesis of impotence. However, the concept of venogenic impotence, characterized as it is by transient erection, and featuring pathological cavernosograms as well as high cavernometric figures, belongs more appropriately to a clinical syndrome and is, therefore far from being unambiguous. Arterial-arterial bypass and selective veins ligation were then introduced to treat cases of "pure" arteriogenic or venogenic insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Erectile Dysfunction↗
PubMed1992

[Non-surgical therapy of impotence: infiltration, iontophoresis, ultrasound, laser].

Surgical therapy is the only useful correction in congenital fibrosis or in hypoplasia of the 'corpora cavernosa', associated with hypospadia or not. On the contrary in not congenital fibrosis of the 'corpora cavernosa' (Peyronie's disease, consequences of priapism, or trauma, complications of pharmaco-prosthesis) are allowed pharmaco-physical treatments (infiltrations, ionophoresis, ultrasound, laser). Pharmaco-physical therapy can be used as the only treatment, which is often resolutive, but it is also useful before or after the surgical operation of the 'corpora cavernosa'. These diseases can give disorders of the erection, until complete impotence is reached. In fact the erectile tissue can't expand, because of the rising fibrosclerosis. Among acquired fibrosis of corpora cavernosa I.P.P. has surely the greatest recurrent: the consistency of our series made possible to achieve significant results with a unified therapeutical protocol. The same management was applied in other, less frequent, penile fibrosis, always with full positive results even if on a small number of patients. We are evaluating a new drug (defibrotide) in the treatment of cavernosal vasculitis. Another one (hyaluronidase) associated to orgotein, could improve its effect against inflammation especially in chronic evolutions. Besides new treatments, we emphasize the prevention of iatrogenic fibrosis with particular regard to cavernous pharmaco-infusions by autoinjections: the training of the patient and the safety of the autoinjectors must be carefully checked by the andrologist to decrease a large amount of complications.

Erectile Dysfunction↗
PubMed1992

[Vacuum therapy].

In the therapy of vasculogenic impotence, the Vacuum Device has been proposed up to now as an "external" prosthesis device with the aim of obtaining a penile erection of sufficient rigidity for penetration, in patients afflicted by vascular or neurological disorders. In the eighties, the experience gained with the use of Intra Cavernous Injections (C.I.D.) (using papaverine, phentolamine and prostaglandin), demonstrated not to be an exclusively palliative therapy ("pharmacological prosthesis"), but to represent as well a sort of "vasoactive exercise" of the erectile tissue. In the nineties, many wondered what could be a valid alternative to the C.I.D. Taking this into consideration, we modified the method of application of Vacuum Therapy. The device was used once a day without the constrictive band applied to the penis root, in order to generate a passive action on the erectile tissue, a sort of "stretching" for the smooth muscle fibers. From January 1990 to December 1991, we treated 78 pts. afflicted by erectile failure. The patients were divided into 3 groups (26 each) of distinct therapy: the first was treated weekly with only endocavernous papaverine administration (20 mg.), the second underwent daily Vacuum Therapy exclusively (10'-15') and the third received a combined therapy: Vacuum Device, daily and C.I.D. with Papaverine (20 mg.) once a week. The results of this treatment are as follows: the patients who underwent Vacuum Therapy daily (2nd and 3rd groups) showed, at the end of the treatment (6 months), a significant improvement in spontaneous erectile ability (14 Pts.-53.8% in the 2nd group; 17 Pts-65.3% in the 3rd group).(ABSTRACT TRUNCATED AT 250 WORDS)

Erectile Dysfunction↗
PubMed1992

[Postoperative impotence].

Increasing interest has developed in recent years about the preservation of sexual function after urological surgery. The pelvic plexus which is formed by parasympathetic visceral efferent preganglionic fibers that arise from the sacral center provides autonomic innervation to the corpora cavernosa. The cavernous nerves emerge from the pelvic plexus and then travel along the posterolateral portion of the seminal vesicle and prostate and then along the membranous urethra. The preservation of the nerve supply of the corpora during urological and pelvic procedures is of vital importance to preserve potency.

Erectile Dysfunction↗
PubMed1991

Development of a second generation stereotactic apparatus for linear accelerator radiosurgery.

Linear accelerator radiosurgery technique is based on a multiple intersecting arc irradiations procedure. The coincidence of the axis of two rotation movements (of gantry and treatment couch) into the isocenter is critical for focusing irradiation. In October 1989, our linear accelerator was changed and the stereotactic apparatus had to be adapted to the new machine. After multiple mechanical tests of the new machine, the stereotactic head frame was fixed to the roller bearing allowing rotation of the couch. The new apparatus is described.

Humans↗
PubMed1991

Trigeminal evoked potentials in patients undergoing percutaneous microcompression of gasserian ganglion.

22 patients undergoing percutaneous microcompression of Gasserian ganglion for the treatment of trigeminal neuralgia were monitored intraoperatively by means of trigeminal evoked potentials (TEPs). The second trigeminal branch was stimulated at the maxillary foramen; evoked responses were recorded using subcutaneous electrodes placed over the scalp. TEPs presented several short-latency waves (called W1, W2, W3, P4, N5, P6, N10) which are generated before and after the ganglion (W1, W2, W3), in the brain stem (P4, N5, P6) and possibly in the cortex (N10); other waves occur within 150 ms after the stimulus (late waves). During compression, W1 did not change, while W2 and W3 as well as P4, N5, P6, N10 and late waves decreased in amplitude: this pattern was noted in the patients who presented with pain relief during the follow-up period. On the contrary, the patients who suffered from pain recurrence did not show similar intraoperative TEP changes. In conclusion, intraoperative TEP derangements may be related to the effectiveness of the compression on the Gasserian ganglion.

Aged↗
PubMed1991

Pressure monitoring inside Meckel's cave during percutaneous microcompression of gasserian ganglion.

During percutaneous microcompression of the gasserian ganglion for the relief of trigeminal neuralgia, a computerized technique for monitoring the pressure inside Meckel's cave was employed in 22 patients. A dedicated transducer connected to a computer records the balloon inflation pressure. Its variations are discernible within tenths of a bar and are plotted in relation to time. The intraoperative pressure inside Meckel's cave is from 0.9 to 2.4 bars. When pressure was low, there was recurrence of pain. The highest values of pressure (1.9-2.4 bars) were observed in most of the patients suffering from untoward side effects. The clinical results seem to be influenced by the level of the intraoperative intracavitary pressure.

Aged↗
PubMed1991

Brain stem acoustic evoked potentials recorded from the human mesencephalon.

Near field brain stem evoked potentials (NF-BAEPs) were recorded by means of an intraparenchymatous electrode placed in the right mesencephalon, during a stereotactic-guided biopsy of a tumor. The traces were compared with far field BAEPs (FF-BAEPs) obtained intraoperatively with scalp electrodes. The findings suggest a peripheral origin of wave II, a bilateral source of wave III and a main contralateral source of wave IV, while wave V seems to take origin mainly from the homolateral upper brain stem. Some intraparenchymatous activities do not project to the scalp. The possible impairments of NF-BAEP due to the presence of the tumor and the challenges of unidimensional single electrode recording are discussed.

Acoustic Stimulation↗
PubMed1991

[Early diagnosis and correct treatment of cryptorchism].

Diagnosis in cryptorchidism should be as early as possible for therapeutical purposes and for the achievement of most positive results. Early but also exact diagnosis allows a selective therapy concerning type of procedure and age of performance. Aims of early diagnosis and selected treatment are: prevention of infertility and eventual decrease of androgenic endocrinal function in the adult; prevention of torsion in retractile testis; prevention of trauma in perineal ectopic situation; prevention of cancer especially in cryptorchidism of the adult; prevention of psychogenic defects of the empty scrotum. Those goals can be obtained by different approaches: pharmacological (hormonal stimulation), surgical (orchidopexy) or by their association. If hormonal administration is not suitable or without results surgical approach will be adopted. Which is now the most suitable age for surgery? Testicular damages begin at the second year of life. Therefore operation should be acted in advance. However, up to date international acknowledgement is in favour of surgical management around the fourth year for the advantages of a more mature anatomical situation without reducing quality of results. Purpose of early diagnosis and selective therapy in cryptorchidism is to avoid irreversibility of severe histological alteration able to compromise gonadal, especially germinal, function. It is never to forget that the high level of infertility in cryptorchidism can be depending not only on evident alteration in number, motility and morphology of spermatozoa but also on morphofunctional defects escaping from the routine seminal examination. All that is in tight connection with the intrinsic dysmorphism in cryptorchism where the abnormal position of the testis is only a partial aspect.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Arterialized penile skin flap: personal technique of reconstruction of the bulbo-membranous urethra].

In bulbar-membranous urethral strictures, the surgical choice treatment should consist on removing the stricture and performing an end to end overlap anastomosis between two flat patent surfaces (Turner-Warwick's technique), whenever possible. When this procedure cannot be used (recurrence, complex or too long strictures), we get different types of tissue in order to create a fitting neo-urethra. To this goal, in the last twenty years we performed, a wide range of urethroplastic techniques (scrotal flap, bladder mucosa free grafts, dermo-epidermal free mesh-grafts). We recently achieved a significant improvement of the post-operative results by an original procedure, which consists in using a very well-vascularized pediculed flap, taken from the complete penile dorsal skin, pulling it to the perineal area, laterally to the cavernous bodies, to be employed for the reconstruction of the neurethra. By this way, we obtain a viable and suitable tissue, reaching even 13 cm in length, so creating a very long segment of neurorethra. A free dermoepidermal mesh-graft should be used to cover the dorsal surface of the penis, in case of enlarged skin uptake. From February 1989 to April 1990, 16 patients affected with complex and relapsed bulbar-membranous urethral strictures, underwent urethroplasty with penile skin island flap. Urethrocistograms and urinary flowmetry performed 3 months from operation demonstrated effective results and all patients referred satisfactory micturation; no fistulas occurred.

Adult↗