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Biomedical subjects

M Lombardi

Publications and source records attributed to M Lombardi.

At least 91 records · Page 5Linked to original sources
PubMed1991

Myocardial perfusion by contrast echocardiography. From off-line processing to radio frequency analysis.

In the last decade, many efforts have been made to study myocardial perfusion by contrast echocardiography. The possibility of differentiating normal from nonperfused myocardium and measuring the extent of the area at risk and myocardial infarction size has already been demonstrated. The aim of this paper is to review the approaches to quantitation of coronary blood flow by contrast echocardiography. In a series of studies, echocardiographic contrast agents have been treated like "deposit tracers." After an upstream contrast injection, myocardial contrast intensity (according to the partition principle) hypothetically reflects the fraction of contrast, and consequently of flow, distributed to the myocardium. A good correlation was found between changes in peak myocardial contrast intensity and corresponding changes in coronary blood flow (r = 0.83). However, this approach is limited by electronic signal distortion and attenuation artifacts. In other studies contrast agents have been treated as intravascular "free-passing" tracers, and (according to the dilution principle) their myocardial transit times hypothetically reflect coronary blood flow. A prolonged myocardial washout halftime with coronary underperfusion has been documented in animal experiments and patients with severe coronary stenosis. However, the majority of contrast agents have intermediate characteristics and do not belong to either category of tracers; furthermore, signal distortion and attenuation phenomena affect the washout phase. The time of myocardial contrast appearance, which is independent of tracer characteristics, permitted the differentiation of baseline conditions from coronary underperfusion but seemed inaccurate in the quantitation of coronary blood flow (r = 0.60).(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast Media↗
PubMed1990

A multicentre follow-up study of 1152 patients with myasthenia gravis in Italy.

A multicentre retrospective study was carried out on the characteristics and course of myasthenia gravis (MG) in Italy. Data from 1152 patients, fairly representative of the myasthenic population seeking medical advice, were analysed for diagnostic criteria, clinical aspects and therapeutic approaches. Mean follow-up was 4.9 years. The disease was correctly diagnosed within 2 years of the onset in 80% of cases. Onset of symptoms peaked in the second and third decade in females and fell between 20 and 59 years in males. At first observation 87% of the patients had generalized MG. Maximal worsening was observed within 3 years in 77% of patients. At the last follow-up, 35% of cases were symptom-free (pharmacological remission 24%, remission without treatment 11%). The more severe the disease at the first observation and at the maximal worsening of symptoms, the lower was the proportion of remissions. Steroids were given in 54% and immunosuppressants in 18%. Thymectomy was performed in 72%, mostly in women, younger than age 40, and with generalized MG. Thymectomy seemed to improve the course of the disease, mostly in patients operated on shortly after diagnosis and those with generalized mild-to-moderate disease and with a normally involuted thymus. MG was lethal in 4% of patients, principally men, older than 40, in grade 3 or worse at first observation, with a short history of disease, and with thymona.

Adolescent↗
PubMed1990

Acquired rod-body myopathy associated with human immunodeficiency virus infection.

A 35 year old homosexual man showed clinical features of myopathy, with progressive muscular weakness of proximal muscles. EMG demonstrated a myopathic pattern; serum CPK was mildly elevated and CSF examination revealed antibodies to HIV and a blood-brain barrier damage. An open biopsy of the quadriceps femoris muscle showed myopathic changes with inflammatory features including a marked variation in fiber size, necrotic fibers and phagocytosis, a profusion of internal nuclei. Fiber type analysis with myosin ATPase reaction revealed that myopathic changes involved both fiber types. Changes in the oxidative enzyme activities were also observed in the degenerating muscle fibers. Electron microscopy showed patterns of myofibrillar degeneration and characteristic rod bodies in 30% of fibers. The close resemblance of the present morphological results with those recently observed in some HIV antibody positive men seems to indicate the existence of a specific structural myopathy associated with AIDS.

Actin Cytoskeleton↗
PubMed1990

A graphic evaluation of the intermaxillary relationship before and after therapy with the Michigan splint.

The effect of the Michigan splint was evaluated graphically in a group of 19 patients. Gothic arch tracings were registered before and after a period of therapy of 4 months, and the two tracings were compared photographically. The position of the apex of the Gothic arch was displaced in most patients, while the shape of the arch was more regular in almost all patients. The validity of the use of the Michigan splint was confirmed.

Adolescent↗
PubMed1990

Inhibition of platelet function during in vivo infusion of isosorbide mononitrates: relationship between plasma drug concentration and hemodynamic effects.

Isosorbide monitrates (IS-2-MN and IS-5-MN), hepatic metabolites of isosorbide dinitrate, inhibit platelet function in vitro very differently, with IS-2-MN being much more potent than IS-5-MN. To assess their antiplatelet properties in vivo and to compare time and dosage requirements, we infused both IS-2-MN and IS-5-MN for 30 minutes, on 2 separate days, into nine patients with stable coronary artery disease, at rates of 4 mg/hr (n = 4) and 8 mg/hr (n = 5). Two additional patients received IS-5-MN at 16 mg/hr. Platelet aggregation and thromboxane (TX) B2 generation in response to various agonists, drug plasma concentrations, and blood pressure were monitored throughout the study. A significant decrease in platelet aggregation and TXB2 production by adenosine diphosphate and adrenaline occurred in seven of nine patients receiving IS-2-MN and in 7 of 11 patients receiving IS-5-MN. Response was dose related, with more patients responding at 8 mg/hr to IS-2-MN (five of five) than to IS-5-MN (three of five), and was maximum at the end of the infusion time, corresponding to peak plasma levels. Patients responding to drug infusions with an inhibition of platelet function were characterized by a greater vascular responsiveness compared to nonresponders, since the decrease in systolic blood pressure (mean +/- SEM) was significantly greater in the former (15.4 +/- 3.2) than in the latter (2.5 +/- 2.1, p less than 0.05). Therefore both mononitrates, when administered at infusion rates between 8 and 16 mg/hr, are accompanied by a consistent inhibition of adenosine diphosphate- and adrenaline-induced aggregation and TX generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1990

[A radiographic assessment of condylar position after therapy with the Michigan plate].

The paper analyses condylar movement in the sagittal plane following four months of therapy using a Michigan-type plate in a group of 19 patients with craniomandibular disorders. An OLTP radiographic examination was used; X-rays carried out before and after therapy were compared using a special image subtraction technique. From the analysis of results it emerged that 63.12% of patients showed a mono- or bilateral condylar movement which was visible by X-ray.

Adult↗
PubMed1989

[Duodenopancreatectomy with conservation of the pylorus].

The authors report on their initial experience with pylorus-preserving pancreatoduodenectomy. In the last three years 11 patients with neoplastic disease of the pancreatic head and ampullary region underwent the above mentioned procedure. The surgical technique carefully preserved the blood supply and innervation to the antro-pyloric region and duodenum was transected 2 cm distal to the pylorus. Postoperative mortality was 9%. Postoperative nasogastric suction was required for eight days (median). Long term results are quite good with a satisfactory restoration of intestinal function and a weight gain of 95% of pre-illness weight. At the present time preserving the pylorus appears an usefull modification of Whipple procedure.

Adenocarcinoma↗
PubMed1989

Frequency domain analysis of contrast echocardiographic images.

Sequences of echocontrastographic images of the dog's myocardium are analysed in the frequency domain for the identification of underperfused areas. Owing to the fact that echo images are contaminated by noise and artifacts, we have applied filtering techniques based on Fourier's methods in sequences of raw frames recorded during perfusion with a contrast agent. Thus we have been able to assess correctly the spatial and temporal distribution of the contrast, i.e. the agent kinetics which parallel the distribution of coronary blood flow, in terms of the time necessary for the flow gradient to reach its maximum value, and to describe such a distribution by a functional image obtained by means of an original procedure.

Algorithms↗
PubMed1989

Somatosensory evoked potentials in Charcot-Marie-Tooth disease.

SEPs by median nerve stimulation have been performed in 18 adult patients (12 males and 6 females) affected by CMTD (type I, 13 patients; type II, 5 patients). All patients underwent MCV studies (median, ulnar, peroneal nerve), SCV studies (median and sural nerve), VEP, BAEP. N9 and N13 peaks were not detectable in 7/13 and 5/13 cases (HMSN type I) while cortical N19 were always recorded. Latency values of all responses were moderately or markedly delayed in all cases with HMSN type I, but proved normal or slightly delayed in HMSN type II cases. The prolonged latencies were mainly related to slowing of peripheral conduction. N9-N13 inter-peak was abnormally prolonged in 2 cases and N13-N19 in 2 other cases; both were prolonged in another case. In another 3 cases an abnormal BAEP was recorded. The few patients with abnormal CCT and BAEP probably belong to a borderline form between HMSN and hereditary ataxias.

Adult↗
PubMed1989

Nonuniformity of the transmural distribution of coronary blood flow during the cardiac cycle. In vivo documentation by contrast echocardiography.

This study was performed to examine the transmural (endocardial vs. epicardial) heterogeneity of myocardial blood flow during the cardiac cycle (systole vs. diastole). Twenty-four contrast echocardiographic injections were performed in seven open-chest anesthetized dogs either into left anterior descending or circumflex coronary artery or into the aortic root. Two-dimensional echocardiography in short-axis view was performed and was digitized off-line into a 256 x 256 pixel matrix with 256 gray levels/pixel. All end-diastolic and end-systolic frames before and to peak contrast were analyzed. A region of interest corresponding to the most intensely opacified myocardial segment was traced, the mean videodensity measured, and the frame of initial contrast appearance detected. The region of interest was divided into three equal parallel layers corresponding to the endocardial, midcardial, and epicardial myocardium. When the echocardiographic contrast effect initially appeared in diastole, the increment in videodensity was greater for the endocardium (131 +/- 48%) than for the epicardium (71 +/- 37% of the increment in videodensity of the entire wall) (p less than 0.05). This inhomogeneity subsequently disappeared in the following end-systolic frame. When the initial echocardiographic contrast effect appeared in systole, intensity was higher in epicardium (136 +/- 83%) than in endocardium (60 +/- 60%) (p less than 0.05). However, in the following diastole, intensity was not significantly different for the two layers. Thus, myocardial contrast echocardiography demonstrates that coronary blood flow is primarily subendocardial in distribution during diastole and subepicardial during systole.

Animals↗
PubMed1989

In vivo actions of organic nitrates on platelet function in humans.

Nitroglycerin and isosorbide dinitrate (ISDN), the most commonly used nitrate vasodilators, have been shown to possess antiplatelet properties. It has also been shown, interestingly, that their inhibition of aggregation (mostly upon ADP and adrenaline) occurs in vivo at concentrations 1-2 log orders lower than in vitro, and in the full therapeutic range. Many different hypotheses may explain such an in vivo/in vitro difference: 1) that nitrates induce prostacyclin synthesis; 2) that they synergize prostacyclin; 3) that they give rise to more active in vivo metabolites; 4) that some other requirement for their action, such as the availability of reducing thiols, may be a limiting factor in the in vitro setting. The discrimination among such hypotheses should contribute new insights into nitrate action at the platelet level. On the basis of experiments on cultured endothelial cells and vascular fragments, we had previously concluded against prostacyclin induction by nitrates. On the other hand, ISDN may decrease the IC50 for prostacyclin in aggregation by suprathreshold doses of various aggregating agents, and therefore, be synergistic with this endogenous antiplatelet substance. Compared to ISDN, the two longer-lived metabolites isosorbide-2- and isosorbide-5-mononitrates (IS-2-MN, IS-5-MN) appear remarkably different in terms of antiplatelet potency in vitro (minimum effective concentrations 10(-7)-10(-6)M for IS-2-MN, 10(-4)M for IS-5-MN, for ADP-and adrenaline-induced aggregation and thromboxane (TX) B2 production).(ABSTRACT TRUNCATED AT 250 WORDS)

Dose-Response Relationship, Drug↗
PubMed1989

[Unusual anatomo-clinical features of thyroid metastasis].

The authors report a case of metastatic tumor from clear cell carcinoma in the thyroid gland occurred in a patient who had his primary tumor previously treated with right nephrectomy. The time interval before the appearance of the metastasis was 6 years. The diagnosis was made preoperatively because of the peculiar biological behavior of the primary tumor. In fact, the metastasis and the primary presented with neoplastic invasion of the middle thyroid vein and the renal vein respectively. The ultrasound examination revealed the vein thrombus arising from the thyroid and reaching the internal jugular vein through the middle thyroid vein. Subsequent fine needle aspiration biopsy confirmed the diagnosis of metastasis from clear cell renal carcinoma. The low grade of malignancy of the primary from the clinical point of view and the absence of other metastatic locations influenced the therapeutic approach.

Carcinoma, Renal Cell↗
PubMed1989

Total thyroidectomy for benign thyroid disease: when and why.

Surgical complications after total thyroidectomy (TT) and subtotal thyroidectomy (STT) are analysed in a series of 364 patients operated on over a 36-month period. All operations were carried out because of the following 3 groups of disease: malignant tumors, multinodular goiter and Graves' disease. The difference among the incidence of surgical complications resulted to be not statistically significant when as discriminating factors the type of surgery or disease were used, while the difference was statistically significant when the results obtained in the 2 groups of patients operated only once or undergoing reoperative surgery for recurrence, were compared. Based on these observations, the surgical approach consistent with the above mentioned types of thyroid disease is reported, and the preference for total thyroidectomy is justified to a larger extent by what has been done to-date also in case of benign thyroid disease. The choice of the type of surgery should always be made, based on a careful clinical and intraoperative assessment of each case.

Adult↗
PubMed1988

Renal involvement in IgD myeloma.

Nine patients affected from IgD myeloma were studied retrospectively in order to elucidate the incidence and peculiar traits of related nephropathy. Eight patients developed chronic renal failure, and as many as 5 were already suffering from renal failure since first admission to the hospital. In 3 cases acute renal failure was the major presenting symptom of the disease. Five patients underwent a regular dialytic treatment. We suggest that the high incidence of renal involvement found in IgD myeloma is related to the high incidence of Bence-Jones proteinuria observed in this disease. Presenting atypical symptoms, among which renal failure is the most important, are misleading and characteristic of the disease. Survival time seems to be negatively influenced by the presence of renal failure at the time of diagnosis.

Adult↗