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Biomedical subjects

F Colombo

Publications and source records attributed to F Colombo.

At least 91 records · Page 5Linked to original sources
PubMed1995

Evaluation of linear accelerator radiosurgical techniques using biophysical parameters (NTCP and TCP).

PURPOSE: Several irradiation techniques are compared with regard to normal tissue complication probability and tumor control probability. METHODS AND MATERIALS: Normal tissue complication probability is calculated using a model based on the "critical element architecture." The probability of controlling an inhomogeneously irradiated tumor is calculated using a model that takes into account the heterogeneity of tumors (different radiosensitivity of clonogens within the tumor and the varying number of clonogens among patients with the same kind of tumor). The ratio of tumor control probability to normal tissue complication probability (therapeutic gain factor) at different levels of dose has been used as a score for the analysis of various irradiation techniques. RESULTS: The best irradiation techniques depends on many factors: irradiation genometry, irradiation field size, choice of the reference isodose, and it is dictated by the pathology of the lesions (noninfiltrating radioresistant tumors, infiltrating radioresistant tumors, noninfiltrating radiosensitive tumors, infiltrating radiosensitive tumors, arterovenous malformations). For the irradiation of the artero-venous malformations it is proposed to insert on the supplemental collimator a flattening filter to reduce the probability of inducing a poorly syncronized obliterative effect. CONCLUSION: We propose that for each kind of pathology to be treated radiosurgically, a proper irradiation strategy should be used.

Humans↗
PubMed1995

Systemic and cerebral kinetics of 16 alpha [18F]fluoro-17 beta-estradiol: a ligand for the in vivo assessment of estrogen receptor binding parameters.

Estrogen receptors are expressed in several brain areas of various animal species, and steroid hormones exert physiologic and biochemical effects on the central nervous system. The aim of the present study was to evaluate in female adult rats, the suitability of 16 alpha [18F]fluoro-17 beta-estradiol ([18F]FES), a selective estrogen receptor ligand, for the in vivo assessment of brain estrogen receptors. This was considered to be a preliminary step in evaluating the potential usefulness of [18F]FES for studies of cerebral estrogen receptors with positron emission tomography (PET) in nonhuman primates and human subjects. We evaluated (a) the time course of the metabolic degradation of [18F]FES in blood; (b) the time course of distribution of the tracer in discrete cerebral areas; (c) the inhibitory effect of increasing doses of cold estradiol on cerebral [18F]FES uptake; and (d) the possibility of in vivo quantification of estrogen receptor binding parameters using both equilibrium and dynamic kinetic analyses. We quantified [18F]FES binding to estrogen receptors using both equilibrium and dynamic kinetic analyses. The results of this study indicate that [18F]FES is a suitable tracer for the measurement of estrogen receptors in the pituitary and hypothalamus, using either the equilibrium or the kinetic analysis. However, [18F]FES is inadequate for the in vivo investigation of estrogen binding sites in brain areas with low receptor density, such as the hippocampus.

Animals↗
PubMed1995

Diurnal blood pressure variability in essential hypertension and vascular reactivity to isometric stress.

The present study was designed to assess the hemodynamic conditions, by means of impedance cardiography methods, and the relation existing between vascular reactivity to isometric stress (isometric handgrip test) and the day/night blood pressure variations, estimated by ABPM. Fifty unselected untreated non-obese EEH adult subjects (WHO class I) with a duration of disease not exceeding 3 years were classified as dippers or non-dippers according to commonly accepted criteria. Twenty three normotensive volunteers acted as controls. SBP, DBP, HR, CI and SVRI were assessed at rest and after IHG test. At rest dippers, non-dippers and controls showed comparable CI. SVRI were more enhanced in EEH than in controls and, although not significantly, in non-dippers than in dippers. During IHG all subjects showed a significant rise of SBP, DBP and HR; CI variations were of comparable size in all groups while SVRI increases were not. Non-dippers showed a significant SVRI rise after IHG in comparison with resting values. In dippers and in controls SVRI increment was insignificantly different in comparison with resting values. Non-dippers showed a closest correlation between BP and SVRI rise during IHG while dippers showed a less consistent association. In conclusion, our data suggest that in adults with short duration EEH the existence of non-dipper condition may be unrelated to myocardial hypertrophy. Blunted nocturnal BP fall is associated with vascular hyper-reactivity revealed by a bigger elevation of SVRI during IHG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Revascularization: light and shadow].

Advances in the knowledge of penile haemodynamics make evidence of two fundamental mechanisms in the physiology of erection: 1) arterial vasodilatation; 2) blockage of venous outflow. Therefore peripheric vasculogenic erectile impotence presents two pathogenetic possibilities: 1) from insufficient arterial flow; 2) from increased venous outflow. It is therefore very important to make the correct diagnosis of the patient with erectile disturbances in order to determine an appropriate therapy. The following examinations are routine tests carried out at our Institution: NPT test, basal and dynamic Doppler-sonography, OOE-OME (evaluation of output obtaining and maintenance erection), basic and dynamic cavernosography, digital angiography, dynamic NMR. After an accurate diagnostic assessment medical treatment can begin, based essentially on the cavernous infusion of vasoactive drugs, in light forms; surgery is resorted to severe cases, or in cases of failure of medical therapy. Proposed operations may be divided into 3 groups: 1) arterio-cavernous by-pass; 2) arterio-arterial by-pass; 3) venous surgery. Since 1978 the successive experiences of the Authors in this field and the better knowledge of penile vascular structures have led to a standardization of the methods used, with partly original techniques (epigastro-dorsal antiflow and orthoflow double by-pass), which, with selective application, have raised the percentage of pulsing anastomoses at 18 months of 82%.

Follow-Up Studies↗
PubMed1995

[Radical surgery and conservation of erection in Peyronie's disease].

The radical surgical option we propose for Peyronie's disease consists in removing the sclero-hyanolitic focus (plaque) and replacing it by an autologous dermal graft taken from the upper outer thigh area. Between 1981 and 1994, we operated 564 patients with Induration penis plastica (IPP), 418 of whom underwent plaque excision and dermal grafting. All could be assessed at two-year follow-up. Two main complications were observed: penile flexure relapse (71 Pts, 17% of cases), and erectile dysfunction with decreased corporal rigidity (84 Pts, 20% of cases). A mild deviation of the penis can occur some months after surgery and it is not due to disease progression (as it should have evolutive characteristics) but is mere scar retraction (44 Pts, 76% of examined relapsed flexures). The degree of this graft retraction is linked to the individual's histologic response and can be due to an idioptic tissular response or to an insufficient size of the patch. In some cases, the post-op penile flexure can result from a progression of disease (14 Pts, 24% of examined relapses flexures) and can be due either to a new "focus" or to an incomplete removal of the previous plaque. As the patient will date the onset of a possible postoperative erectile deficit from the time of the operation, it is advisable to assess preoperatively the real erectile ability of all patients. Furthermore, a post-op impaired erectile response (84 Pts, 20%) could result from a subalbuginear fibrosis of the erectile tissue that leads to a caverno-occlusive dysfunction (60%). In more than 35% of patients we found a psychogenic component, due to post-surgical stress, that involves an adrenergic hypertone with peripherical vasoconstriction. In few cases (4%) the post-op erectile dysfunction is the consequence of peroperative arterial damages that results in hypoaesthesia of the glans (injury of dorsal arteries) or in failure to obtaining corporal rigidity (damage of cavernosal arteries). A review of our experience involving plaque excision and dermal grafting led us to propose this option in case of mechanical disturbance during coitus and when the association of erectile dysfunction can be excluded.

Follow-Up Studies↗
PubMed1994

Cardiac function study in hard metal workers.

The induction of cardiac effects in hard metal workers is uncertain. This study investigates cardiac function of a group of 31 hard metal workers with or without pulmonary disease. The average duration of exposure to cobalt containing dusts was 10.4 years (range 1-30), while the environmental levels of cobalt exposure ranged from 0.09 to 13.6 mg/m3 Co. Cardiac function has been studied by: ECG (electrocardiogram), exercise test (ET), ECG 24 h according to Holter (ECGH), echocardiogram (ECHO) and radionuclide angiocardiography with 99Tc (RNA). The aims of this work were (i) to show the existence of cobalt myocardiopathy in the workers analyzed and, (ii) to find an early indicator of cardiac dysfunction which could be used in the clinical examination of hard metal workers. Within the group of patients with hard metal lung disease, cases of myocardiopathy of doubtful aetiology have been found. The cardiac indexes obtained through RNA show ventricular dysfunction in healthy hard metal workers which could be a manifestation of initial pulmonary artery hypertension or of an early occult cor pulmonale due to an unknown fibrotic lung disease.

Adult↗
PubMed1994

Patterns of care and survival in non small cell lung cancer: 15 years' experience in a general hospital.

BACKGROUND: Transferring results derived from clinical research into practice is particularly difficult in lung cancer where clear indications for treatment are defined only for selected subgroups of patients. Studies on hospital-based lung cancer population could provide data for quantifying this issue. PATIENTS AND METHODS: This was a follow-up study of consecutive, first-diagnosis cases referred to the in-and outpatient cancer clinics of a large italian general hospital between January 1975 and December 1990. Data were collected from medical records and recorded on ad hoc standardized forms. Analysis focused on changes in distribution over time of patient-related characteristics, prevalence of specific treatment strategies and survival of the study population. RESULTS: 1345 primary non small cell lung cancer cases were reviewed and 1125 were fully evaluable. In early stages (510/1125, 45%) only 237 patients actually underwent surgery. In this group surgery increased from 36 to 69% whereas chemotherapy decreased from 58 to 15%. In the advanced group (615/1125, 55%) chemotherapy was the preferred treatment but combined modalities tripled over time (from 4 to 12%). No significant changes in survival were observed within each group over time. CONCLUSION: Despite changes in the therapeutic approaches, mortality from lung cancer does not seem reduced over time. Since the proportion of cases that could potentially benefit from "active" treatments is small, for the large majority of patients a switch in clinical research from a cure to a care-oriented strategy should be considered.

Aged↗
PubMed1994

Linear accelerator radiosurgery of cerebral arteriovenous malformations: current status.

228 patients affected by cerebral arteriovenous malformations (AVMs) underwent linear accelerator radiosurgery. Follow-up ranges from 1 to 100 months (mean 42 months). Complete angiographic obliteration was achieved in 47% of treated patients at one year and 80% at 2 years. 17 haemorrhages were observed after treatment and 6 patients died from them. No bleeding took place after complete angiographic obliteration. 11 patients suffered for radionecrosis. In 6 patients complete recovery was obtained with corticoid medication. The aim of this study is to present our results and to evaluate the effect of irradiation on the risk of bleeding after radiosurgery. Patients were considered at risk in the time lapse after irradiation and before angiographic obliteration or other definitive treatment or death. Patients were followed from the date of radiosurgery and the number of haemorrhages were recorded every six months. In our series the bleeding risk in patients harbouring incompletely obliterated AVMs decreases from 8% in the first year after radiosurgery to 0% starting from the 24th month of the follow-up.

Adolescent↗
PubMed1994

Antihypertensive efficacy and tolerability of different drug regimens in isolated systolic hypertension in the elderly.

The pharmacological treatment, mainly based on diuretics, of isolated systolic hypertension (ISH) has recently been shown to reduce the risk of stroke and coronary heart disease in the elderly. The purpose of this study was to compare the antihypertensive effect and tolerability of different drug regimens in elderly subjects with ISH (systolic blood pressure--SBP-- > or = 160 mmHg and diastolic blood pressure--DBP-- < 90 mmHg). A multicentre, randomized, controlled open trial was planned in the general practice setting. Four widely used treatment schedules were tested: hydrochlorothiazide 25 mg plus amiloride 2.5 mg (H+Am), nifedipine slow release 20 mg (N), atenolol 50 mg (At) and atenolol 25 mg plus chlorthalidone 6.25 mg (At+C). After a baseline evaluation, 308 patients (76.3% female, mean age 75.3 +/- 7.1 years) were randomized and followed up for 6 months. After 3 months the drug dosage was doubled if the systolic blood pressure goal (SBP < 160 mmHg and SBP reduction of at least 20 mmHg) had not been reached. Ninety-four subjects (30.5%) presented contraindications to beta-blockers. At the 3rd- and 6th-month visits all treatment groups, except At, showed a significant reduction in SBP compared to the control group; DBP showed no significant reduction in any group at any time. At the end of the follow-up the percentage of hypertensives who had reached the BP goal was 14.6% in the control group, 52.9% in H+Am, 54.8% in N, 28.6% in At and 52.2% in At+C.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Treatment of primary or metastatic pleural effusion with intracavitary cytosine arabinoside and cisplatin. A phase II study.

Thirty-three patients with microscopically verified primary or metastatic malignant pleural effusion were studied: 7 had malignant mesothelioma and 26 metastatic pleural disease. The treatment was based on biochemical and clinical studies which show a synergy between cytosine-arabinoside (Ara-C) and cisplatin. These drugs were instilled in the pleural cavity at the dose of 100 mg for Ara-C and 100 mg/m2 for cisplatin. The cavity was drained after 4 h. If it was possible, the treatment was repeated weekly for 3 times and, after a 6-week rest, it could be started again with the same schedule. The overall response rate (complete plus partial remissions) was 74%. Toxicity was mild or moderate. We conclude that the combination of Ara-C and cisplatin is well tolerated and produces a high response rate in the treatment of malignant pleural effusions.

Adult↗
PubMed1994

Brain stem and motor evoked responses in "locked-in" syndrome.

A patient suffering for an ischemic "locked-in" syndrome following a subarachnoid hemorrhage, was evaluated with brain stem acoustic evoked potentials (BAEPs), short latency somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs). Neuroradiological findings failed to reveal any lesion in the brain stem, while a transcranial Doppler showed increased flow velocity upon the basilar artery, suggesting vascular spasm. BAEPs were normal and SEPs showed to be slightly impaired while MEPs upon magnetic cortical stimulation were heavily deranged. Neurophysiological investigations appeared remarkable for the early diagnosis of the disease, when neuro-radiological findings were still negative.

Adult↗
PubMed1994

[Island flap in the surgical treatment of hypospadias].

Surgery of hypospadias represents an interesting field of innovatory ideas. Many methods may be suitable and many modifications can be performed. There is no one method for all kinds of hypospadias. It is necessary to find the right method for each patient. The result often depends upon the experience of the surgeon with a particular method. The choice between straightening and urethroplasty in one or two stages depends on cost-benefit ratio and evolution at distance of the straightening must be taken into account as well tissue consumption imposed by the urethroplasty, with one stage straightening that makes reintervention very difficult. In the latter case, a multi-stage operation will be necessary with flaps for urethroplasty after the straightening, or, in a more developed penis, a shortening operation according to Nesbit. With two-stage method, in case of relapsed curvature, this can easily be treated, if tissue is available. For a good result of urethroplasty the ability of surgeon, a constant calibration of the canal, plenty of elastic tissue for the neo-urethra, care not to suture on these planes, are highly important. In our opinion Duplay's method observes these requisites. Two-stages surgery allows easy correction of any eventual relapsing incurvature, with no problems for the following urethroplasty. One-stage surgery allows the problems to be resolved in a single surgical Step, but involves the risk of tissue consumption and proximal stricture.

Follow-Up Studies↗
PubMed1994

Human biodistribution, dosimetry and clinical use of technetium(III)-99m-Q12.

UNLABELLED: Technetium(III)-99m-Q12, trans-(1,2-bis(dihydro-2,2,5,5-tetramethyl- 3(2H)furanone-4-methyleneimino)ethane)bis(tris(3-methoxy-1-propyl) - phosphine)technetium(III)-99m, is a nonreducible complex of Tc(III) which is herein evaluated as a myocardial perfusion imaging agent. METHODS: The biodistribution and dosimetry of 99mTc-Q12 were assessed in 10 normal volunteers, while its potential clinical use was evaluated in 70 patients. RESULTS: Safety parameters measured up to 24 hr postinjection demonstrate no clinically significant drug-related adverse reactions. Technetium(III)-99m-Q12 exhibits good heart uptake (2.2% injected dose at 1 hr postinjection under resting conditions) and no detectable myocardial washout or redistribution up to 5 hr postinjection. The biodistribution is characterized by very rapid hepatobiliary clearance which allows effective myocardial imaging at times as short as 15 min postinjection. Blood and plasma clearances and myocardial uptake are rapid, while lung uptake is minimal. The heart-to-lung and heart-to-liver ratios are higher at stress than at rest, independent of the time elapsed between injection and image acquisition, and independent of whether the patient is fasted or fed after tracer administration. A preliminary correlation shows that 46/47 patients with angiographically demonstrated CAD also have perfusion defects demonstrated by 99mTc-Q12. CONCLUSIONS: On the basis of the studies reported herein, 99mTc-Q12 appears to be a promising myocardial perfusion imaging agent.

Adult↗
PubMed1994

[NPT: nocturnal penile tumescence test].

The recording of the variations of penile tumescence and rigidity during nocturnal unconscious erections that usually occur with the REM phases of sleep, has been considered the diagnostic tool of choice in the workup of erectile disturbances for a number of years. Such a success is partly due to its absence of invasiveness. Moreover this test was believed to allow to differentiate between the psychogenic and organic origin of impotence. As some authors have recently reported, anxiety state (common among patients who undergo invasive andrological procedure in the office) can at times influence the content of the dream state, thus negatively affecting the spontaneous nocturnal erections. Besides, sleep disturbances such as apnea and motor agitation can also induce erroneous interpretations of NPT graphs. Further, dysfunctions at the level of the cortex and the spine still allow the occurrence of nocturnal tumescence but determine an erectile deficit in the awake state. Clinically, all this poses new questions about the effectiveness of the NPT test in the study of the origin of impotence. The diagnostic methods, despite its world-wide diffusion, remains, under certain aspects, obscure: the operative details and, above all, its interpretative criteria. All this impedes the achievement of uniformity in the evaluation of the results obtained thanks to this test (e.g. the number and duration of erectile episodes, the interpretation of tumescence on its own, of the basal-apical dissociation, of the erectile episodes occurring immediately before waking, and of those of short duration).

Aged↗
PubMed1994

[The cavernosometry].

The recent clinical and experimental research innovations in Andrology make possible the following classification of impotence: "Failure to initiate" "Failure to store" "Failure to fill" The last aspect, including veno-occlusive dysfunction, is continuously reevaluated by andrologic studies. The main diagnostic procedure of this complex problem, in constant evolution, is represented by cavernometry. Recently, but with full success, we are utilizing direct radioisotopic penogram in video sexy stimulation: in preselection function but probably in future with substitutive function of the more invasive and traditional cavernometry. In spite of this methodologic progress the findings of cavernometry are in continuous discussion as in tumultuous evolution, in anatomo-physiological environment, is the intracavernous district that, for many aspects, necessity of ulterior histochemical, pharmacodynamic and neurophysiological acknowledgements.

Diagnosis, Differential↗