Biomedical subjects

M Lombardi

Publications and source records attributed to M Lombardi.

At least 19 recordsLinked to original sources

PubMed1992

Myocardial washout of sonicated iopamidol reflects coronary blood flow in the absence of autoregulation.

OBJECTIVES: The aim of the study was to evaluate the relation between measurements derived from myocardial contrast echocardiography and coronary blood flow. BACKGROUND: Contrast echocardiography has the potential for measuring blood flow. METHODS: In six open chest anesthetized dogs, the left circumflex coronary artery was cannulated and perfused with blood drawn from the left femoral artery. While adenosine was infused into the circuit, circumflex flow was generated by a calibrated roller pump to the point of abolishing coronary autoregulation. At each of 25 levels of coronary blood flow, paired bolus injections of sonicated iopamidol were performed proximal to a mixing chamber. The perfused area of the left circumflex coronary artery was labeled by radioactive microspheres injected into the perfusion line. Two-dimensional echocardiographic images of the left ventricular short axis were digitized off-line, and myocardial videodensity was measured in the area perfused by the left circumflex coronary artery to generate time-intensity curves. RESULTS: The washout slope of curves showed a good correlation with coronary blood flow, ranging from 0.5 to 12.5 ml/min per g of tissue. This correlation was good both in individual dogs (correlation coefficient [r] ranging from 0.78 to 0.96) and in the group of animals as a whole (r = 0.85). Washout slope also showed a good correlation with coronary diastolic pressure (r = 0.80), which ranged from 23 to 114 mm Hg, suggesting a possible primary effect of pressure on contrast washout. However, coronary blood flow appeared to be a stronger predictor of washout slope (partial F = 26.5, p < 0.001) than did perfusion pressure (partial F = 5.9, p < 0.05 by multiple regression). The injection to injection variability in myocardial washout slope appeared to be high (24%). The gamma variate fitting of curves did not improve the correlation with coronary flow (r = 0.78). CONCLUSIONS: Myocardial washout of sonicated iopamidol reflects coronary blood flow in a model in which coronary autoregulation is abolished.

Adenosine↗

PubMed1992

Monitoring of somatosensory evoked potentials during carotid endarterectomy.

Somatosensory evoked potentials (SEPs) were monitored in the course of 368 carotid endarterectomies (CEAs) carried out in 312 patients. In an initial group of 26 patients the shunt was used routinely while in a second group, involving 342 CEAs, it was applied selectively on the basis of modifications which the SEP underwent during clamping. The criterion for shunting was the progressive reduction, up to 50%, of the N20-P25 amplitude. New postoperative neurological deficits appeared in 6 patients, all of whom displayed a transitory SEP flattening. The SEPs of 2 of these returned to normal by the time they awoke and both showed a clinical deficit homolateral to the operated side. In only 2 cases did the deficit fail to regress completely and their postoperative CT scans revealed ischaemic lesions. A positive relationship emerged between SEP changes and back pressure values; nonetheless, as many as 75% of the patients with low residual back pressure values (less than 25 mmHg) tolerated the clamping. SEP monitoring appears to provide a reliable basis for selectively applying a shunt when there is a high risk of haemodynamic ischaemia during clamping.

Adult↗

PubMed1992

Efficacy of intranasal administration of neostigmine in myasthenic patients.

The efficacy of intranasally administered neostigmine was tested in 22 patients with generalized myasthenia gravis (MG). Topical therapy to the highly vascularized oropharynx proved to be quickly effective in 5-15 min both clinically and electrophysiologically. Twenty-eight MG patients were then recruited from different centres and their morning doses of oral pyridostigmine were substituted with intranasal neostigmine over a period of 2 or 3 weeks. Intranasal neostigmine proved to be equally efficacious in this regimen. No side-effect was noted even in 4 patients treated in this way for 1 year. Intranasal administration of anti-acetylcholinesterase may be very beneficial: (1) for patients with irregular absorption of oral doses; (2) early in the morning and every time a fast and temporary effect is needed; (3) in bulbar impairment and emergencies, in which a handy atomizer may be life-saving.

Administration, Intranasal↗

PubMed1992

Discordance between responses of contrast echo intensity to increased flow rate in human coronary circulation and in vitro.

According to the Stewart-Hamilton equation flow is inversely related to the area under the time-concentration curve produced by the transit of a detectable indicator. To verify the applicability of this principle for contrast echocardiography, we bolus injected a saccharide echo contrast agent (0.8 ml) into an in vitro circulatory model at variable flow rates. Two-dimensional echo images were digitized, and curves demonstrating the ratio of videointensity over time were derived. As expected, flow was inversely related to the area under the curves (r = 0.93). To apply this principle to human coronary circulation, we bolus injected sonicated iopamidol (4 ml) into the normal left coronary artery of six patients at baseline and after intravenous administration of dipyridamole (0.84 mg/kg in 10 minutes). Echo images were digitized, and myocardial time-intensity curves were derived. The area under the curve after dipyridamole administration (210 +/- 128 gray level.sec) did not appear significantly different from that at baseline (177 +/- 80 gray level.sec). Thus a mismatch exists between contrast echo data obtained in vitro and in human coronary circulation.

Aged↗

PubMed1992

[Aesthesiometry of the cornea after refractive corneal surgery].

The corneal sensibility was examined with the aesthesiometer of Draeger in 41 patients after refractive corneal surgery, 31 patients after radial keratotomy, 5 after epikeratophakia, 5 after excimer laser ablation. It could be shown that after radial corneal incisions the sensibility remains normal. After epikeratophakia the corneal sensibility is asensible even 3 years after operation. The lenticle periphery shows an increase of sensibility after 6 months. Excimer patients with "haze" showed a significant hyposensibility in the centre. The central sensibility showed normal values after a normal corneal wound healing.

Adult↗

PubMed1992

Hepatitis B vaccination in dialysis patients and nutritional status.

35 dialysis patients underwent anti-HBV vaccination. We classified patients in responders or non-responders using an anti-HBs titer of 50 UI/l as the discriminating serum level and tried to assess whether the antibody response bears any relationship with the nutritional status. 26 patients (74%) reached the target atb titer, which was maintained during follow-up (average 360 UI/l). The weak response in the other 9, with values never exceeding 20 UI/l, was short-lived. Anthropometric and impedenziometric parameters were higher in responders than in nonresponders, but the difference did not reach statistical significance. We conclude that the atb titer which discriminates uremics in responders or not must be greater than 50 UI/l and that the nutritional status may interfere with the seroconversion rate, but this conclusion needs to be validated in a wider population.

Adult↗

PubMed1991

Vasopressin alters the mechanism of apical Cl- entry from Na+:Cl- to Na+:K+:2Cl- cotransport in mouse medullary thick ascending limb.

Experiments were performed using in vitro perfused medullary thick ascending limbs of Henle (MTAL) and in suspensions of MTAL tubules isolated from mouse kidney to evaluate the effects of arginine vasopressin (AVP) on the K+ dependence of the apical, furosemide-sensitive Na+:Cl- cotransporter and on transport-related oxygen consumption (QO2). In isolated perfused MTAL segments, the rate of cell swelling induced by removing K+ from, and adding one mM ouabain to, the basolateral solution [ouabain(zero-K+)] provided an index to apical cotransporter activity and was used to evaluate the ionic requirements of the apical cotransporter in the presence and absence of AVP. In the absence of AVP cotransporter activity required Na+ and Cl-, but not K+, while the presence of AVP the apical cotransporter required all three ions. 86Rb+ uptake into MTAL tubules in suspension was significant only after exposure of tubules to AVP. Moreover, 22Na+ uptake was unaffected by extracellular K+ in the absence of AVP while after AVP exposure 22Na+ uptake was strictly K(+)-dependent. The AVP-induced coupling of K+ to the Na+:Cl- cotransporter resulted in a doubling in the rate of NaCl absorption without a parallel increase in the rate of cellular 22Na+ uptake or transport-related oxygen consumption. These results indicate that arginine vasopressin alters the mode of a loop diuretic-sensitive transporter from Na+: Cl- cotransport to Na+: K+: 2Cl- cotransport in the mouse MTAL with the latter providing a distinct metabolic advantage for sodium transport. A model for AVP action on NaCl absorption by the MTAL is presented and the physiological significance of the coupling of K+ to the apical Na+: Cl- cotransporter in the MTAL and of the enhanced metabolic efficiency are discussed.

Animals↗

PubMed1991

Prognosis of myasthenia gravis: a multicenter follow-up study of 844 patients.

The prognosis of myasthenia gravis (MG) was assessed retrospectively using life-table analysis in 844 patients followed up for a mean period of 5 years in 3 major Italian centers. The chance of achieving at least a 1-year remission after treatment withdrawal (complete remission) was assessed as a specific end-point in the whole population and in selected subgroups with reference to the principal prognostic variables. The cumulative probability of complete remission was 1% by 1 year, 8% by 3 years, 13% by 5 years, and 21% by 10 years. The only variables correlated to the chance of complete remission were younger age at onset of MG, lower severity of symptoms at onset and nadir, and shorter disease duration at diagnosis. In addition, thymectomy and early surgery seemed to influence the chance of remission. Other factors (including the presence of thymoma) did not significantly influence the outcome of the disease.

Adult↗

PubMed1991

Perceptibility of condylar displacement through transcranial radiographs and split-cast technique on dry skull.

The authors compared the limit of perceptibility of transcranial radiographs and of the split-cast technique in detecting differences in condylar position. The study was carried out on two dried human skulls. The results indicated the split-cast method was superior to the radiographic method as it allowed differences in condylar position of 0.2 mm, both in sagittal and frontal plane, to be detected. The limit of perceptibility of transcranial radiographs for position differences in the sagittal plane was 0.6 mm for naked-eye examination and 0.2 mm when using the subtraction method. Differences in condylar position even as large as 0.6 mm in the frontal plane could not clearly be seen by naked-eye examination, and with the subtraction technique only if they were of at least 0.4 mm.

Humans↗

PubMed1991

Effectiveness of steroid treatment in myasthenia gravis: a retrospective study.

The records of 142 patients with generalized autoimmune myasthenia gravis who had been treated with steroids as the single immunosuppressive agent, collected at regular intervals, were employed for a retrospective evaluation. The effectiveness of treatment was assessed after 24 months; the data from the 6th and 12th months were also considered. After 24 months, 63.4% of the whole sample had improved (33.8% were in clinical or pharmacological remission); 13.4% were unchanged or had worsened and 22.3% had moved to a different immunosuppressive treatment. The rate of positive outcome was higher in patients over the age of 40 at disease onset.

Adolescent↗

PubMed1991

Treatment of myasthenia gravis with high-dose intravenous immunoglobulin.

We treated 37 patients affected by autoimmune generalized myasthenia gravis (MG) with high-dose intravenous gammaglobulin (HDIVIg), 400 mg/kg per day on 5 consecutive days. A one-degree improvement of Oosterhuis global clinical classification of myasthenic severity (OGCCMS), the disappearance of bulbar involvement or both were recorded 12 days after the beginning of the treatment in 70.3% of the patients and persisted up to 60 days in 58.7%. A two-degree improvement of OGCCMS was recorded in 54.1% of the patients and it was maintained up to 60 days in 37.8%. The percentage of improvement did not significantly differ between patients entering the treatment in a long-standing, drug-refractory stationary phase of the illness (n = 26) and patients who received HDIVIg in an acute phase of MG (n = 11). None of the patients experienced side effects. Our data indicates that HDIVIg is an interesting, virtually riskless therapeutic choice for MG patients, and allows the planning of a controlled trial versus plasma-exchange.

Adolescent↗

PubMed1991

[Clinical considerations on a case of giant ovarian cysts].

The Authors report a case of giant ovarian cyst recently observed. The diagnosis was quite difficult because the patient refused for long time to undergo clinical examination. Following elective surgery a complete recovery was obtained, and at six months from the operation the patient is in good health.

Adult↗

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↗