Biomedical subjects
Publications and source records attributed to G Santoro.
Three different devices were used to close secundum-type atrial septal defects in 28 patients. The "Amplatzer" is associated with an easier and shorter procedure than are the "Sideris Buttoned Device" and the Microvena "Angel Wings" devices.
Oxygen radical generation induced by postischemic reperfusion can overwhelm endogenous radical scavenging systems, resulting in "oxidative stress." Release of oxidized glutathione (GSSG) upon reflow has been taken as evidence for the occurrence of oxidative stress in postischemic hearts. However, demonstration that GSSG release is due to oxygen radicals and not to other consequences of ischemia/reperfusion is lacking. To address this issue, isolated rabbit hearts underwent 30 min of global ischemia at 37 degrees C. At reflow, control hearts were perfused with standard buffer for 45 min (n = 8); treated hearts received the oxygen radical scavenger superoxide dismutase (hSOD) for 15 min, followed by 30 min of standard perfusion (n = 8). During reperfusion control hearts showed a prominent release of GSSG, which peaked 5 min after reflow. Interestingly, GSSG release was still significantly elevated 45 min into reperfusion, at a time when oxygen radical generation has long ceased. In contrast, in hSOD-treated hearts GSSG release was negligible. Prevention of oxidative stress was also associated with significantly greater recovery of function. Thus, GSSG release occurs in postischemic hearts as a direct consequence of oxygen radical generation, and it may outlast the initial oxidant load.
The same system of intraaortic balloon pumping has been used in 2 infants after surgical repair of anomalous origin of the left coronary artery from the main pulmonary artery. Intraaortic balloon pumping was started in the first patient on the second postoperative day, whereas in the second patient it was started before the patient was weaned from cardiopulmonary bypass. Both patients survived. In the first patient intraaortic balloon pumping improved the low cardiac output, which had failed to respond to maximal inotropic support, whereas in the second it maintained hemodynamic stability.
PURPOSE: We report our experience with endoluminal stent placement after percutaneous transluminal angioplasty for the treatment of post-transplant renal artery stenosis. MATERIALS AND METHODS: From October 1992 to September 1996, 8 stents were successfully implanted in 7 patients affected by resistant transplant renal artery stenosis. All transplanted kidneys were procured from cadaver donors. The patients were routinely evaluated with duplex sonography and the median interval between transplantation and stenosis detection was 7.4 months (range 0.5 to 17). When serious renal stenosis was diagnosed (greater than 50%), selected angiography and percutaneous transluminal angioplasty were performed. In 8 cases (7 patients) an endoluminal metallic Palmaz stent was placed in the site of the restenosis. One patient received 2 stents repeatedly positioned in different stenosis sites. RESULTS: No major complications occurred. Clinical outcome was positive in 5 patients (71.4%) and Stenosis recurred in 2 (28.5%) (less than 50% and less than 35%, respectively). Median followup after stent placement was 14.8 months (range 1 to 37). CONCLUSIONS: Percutaneous endoluminal stent procedures after resistant transplant renal artery stenosis or for ex novo treatment for severe anastomotic stenoses appears to be promising. Longer followup periods are necessary for true evaluation of this procedure.
In this paper, we report on the use of stents in the treatment of late-onset post-Mustard systemic venous obstruction in three patients with clinical signs of obstructive caval syndrome. After unsuccessful balloon dilation, Palmaz-Schatz stents were implanted at the veno-atrial junction. Further dilation has been achieved using high-pressure balloons. Vessel diameter increased from 4.4+/-1.8 to 13+/-1.7 mm (P < 0.05) and the trans-stenotic pressure gradient dropped from 8+/-6 to 0 mmHg (P < 0.01), with clinical improvement. After 26+/-4 months of non-invasive follow-up, no signs of recurrent stenosis were observed. Stent implantation is effective in the treatment of systemic venous obstruction after Mustard operation.
In liver mitochondria isolated from hypothyroid rats, the rate of ATP synthesis is lower than in mitochondria from normal rats. Oligomycin-sensitive ATP hydrolase activity and passive proton permeability were significantly lower in submitochondrial particles from hypothyroid rats compared to those isolated from normal rats. In mitochondria from hypothyroid rats, the changes in catalytic activities of F0F1-ATP synthase are accompanied by a decrease in the amount of immunodetected beta-F1, F0 1-PVP, and OSCP subunits of the complex. Northern blot hybridization shows a decrease in the relative cytosolic content of mRNA for beta-F1 subunit in liver of hypothyroid rats. Administration of 3,5,3'-triodo-L-thyronine to the hypothyroid rats tends to remedy the functional and structural defects of F0F1-ATP synthase observed in the hypothyroid rats. The results obtained indicate that hypothyroidism leads to a decreased expression of F0F1-ATP synthase complex in liver mitochondria and this contributes to the decrease of the efficiency of oxidative phosphorylation.
We evaluated the involvement of the sarcolemmal ATP-sensitive K+ channel in the depolarization of skeletal muscle fibers occurring in an animal model of human hypokalemic periodic paralysis, the K+-depleted rat. After 23-36 days of treatment with a K+-free diet, an hypokalemia was observed in the rats. No difference in the fasting insulinemia and glycemia was found between normokalemic and hypokalemic rats. The fibers of the hypokalemic rats were depolarized. In these fibers, the current of sarcolemmal ATP-sensitive K+ channels measured by the patch-clamp technique was abnormally reduced. Cromakalim, a K+ channel opener, enhanced the current and repolarized the fibers. At channel level, two open conductance states blocked by ATP and stimulated by cromakalim were found in the hypokalemic rats. The two states could be distinguished on the basis of their slope conductance and open probability and were never detected on muscle fibers of normokalemic rats. It is known that insulin in humans affected by hypokalemic periodic paralysis leads to fiber depolarization and provokes paralysis. We therefore examined the effects of insulin at macroscopic and single-channel level on hypokalemic rats. In normokalemic animals, insulin applied in vitro to the muscles induced a glybenclamide-sensitive hyperpolarization of the fibers and also stimulated the sarcolemmal ATP-sensitive K+ channels. In contrast, in hypokalemic rats, insulin caused a pronounced fiber depolarization and reduced the residual currents. Our data indicated that in hypokalemic rats, an abnormally low activity of ATP-sensitive K+ channel is responsible for the fiber depolarization that is aggravated by insulin.
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The conjunctival epithelium of the Mongolian gerbil (Meriones unguiculatus) was studied using the transmission and scanning electron microscopy. The superficial cells of the conjunctival epithelium were isoprismatic in shape and were covered, on their luminal surface, with microplicae. They were connected with the adjacent cells by junctional complexes and desmosomes. Some of the superficial cells were partially or completely detached from the underlying intermediate cells: this morphological pattern was interpreted as an expression of cellular renewal of the conjunctival surface. Goblet cells were either isolated or gathered in clusters: in any case, they were firmly connected with the adjacent epithelial cells. The apical part of the goblet cells was covered with a great number of long microvilli: they showed a variety of morphological aspects, which were interpreted as occurring in a sequential pattern during the secretory process. The Mongolian gerbil can be considered among the laboratory animals used for ophthalmic research.
We report the case of a 74-year-old woman who underwent an elective procedure to replace her mitral valve with a 27-mm CarboMedics bileaflet valve (CarboMedics, Inc.; Austin, Tex) to correct mitral incompetence. Massive thrombosis of the prosthesis was clinically evident on the 6th postoperative day, despite administration of warfarin therapy according to our usual protocol. After an unsuccessful attempt at thrombolysis with recombinant tissue plasminogen activator, the mechanical prosthesis was replaced with a bioprosthesis. The cause of the thrombosis is unknown, but transient suboptimal anticoagulation is assumed to be responsible. Although very early massive valve thrombosis is a rare occurrence, it is a known risk of prosthetic valve implantation. Antiplatelet therapy, in addition to the usual warfarin anticoagulation, can help to prevent it. If thrombosis is diagnosed, it can be managed by thrombolysis or, when thrombolysis is unsuccessful, by reoperation. Transesophageal echocardiography is fundamental in the diagnosis and management of this sequela.
The knowledge of echocardiographic pitfalls, which may impair the correct indication for surgery of aortic coarctation, is of great importance to pediatric cardiologists. We believe that only the suspicion of coronary artery anomalies is a clear indication to perform a cardiac catherization.
Between 1989 and 1995, 96 consecutive infants affected by isolated ventricular septal defect (VSD) were submitted for primary correction at a median age of 4 months. Of the 96, 60 (group I) underwent surgery on the base of a 2-dimensional Doppler echocardiographic (DD echo) test alone. The preoperative DD echo anatomic definition of the type of VSD was confirmed at surgery in all 60 patients without false-positive results in terms of additional cardiac anomalies. There were 2 false-negatives: in 2 patients an associated cardiac anomaly was not detected by DD echo and required a second surgical procedure after postoperative cardiac catheterization. During the same period 36 infants (group II) underwent surgical closure of isolated VSD on the basis of cardiac catheterization and angiocardiography in addition to DD echo. The retrospective comparison between the 2 groups revealed no significant difference in terms of sensitivity and specificity of the diagnostic tools, early and late mortality after surgical correction, postoperative hospital stay, and need for late cardiac catheterization and surgery. We conclude that after an accurate selection, most of the infants with uncomplicated VSD can safely undergo primary repair on the basis of DD echo alone.
BACKGROUND: These is no consensus in the literature regarding the differentiation of conjunctival goblet cells in vertebrates. METHOD: The conjunctival epithelium of the chick was studied before and after hatching in order to demonstrate the morphological evolution of the goblet cells. The entire conjunctiva was processed for light microscopy either on semithin sections stained with toluidine blue-pironine or on traditional sections stained with Alcian blue pH 2.5-PAS. RESULTS: It was possible to demonstrate that goblet cells underwent remarkable changes in their secretory activity. At 12 h after hatching, isolated Alcian blue-positive cells were present in the fornix. At 24 h after hatching, cells positive for both Alcian blue and PAS were scattered among epithelial cells. Two days after hatching, cells which reacted positively only to PAS were also present. CONCLUSION: It is suggested that the differentiation of conjunctival goblet cells occurs first in the fornix, probably due to the particular vascular environment of this region, and then spreads all over the conjunctiva.
AIM: Little is known yet about the clinical aspects of ventricular pre-excitation in pediatric age. In order to define clinical course, assess the risk of malignant arrhythmia and evaluate indications for ablative therapy, we studied 82 consecutive pediatric patients (pts) with this affection (61 males-21 females; mean age at diagnosis 5.1 years, range 1 day-15 years). RESULTS: Mean follow-up time was 66 months (range 3-252). Fifty-six pts (68.3%) were asymptomatic. One patient, who was affected with hypertrophic cardiomyopathy and died suddenly when she was 2 while her cardiac rhythm was being monitored, had an EKG pattern of asystolia. In 28 pts (19 m - 9 f, 34.1%), episodes of reentrant atrio-ventricular tachycardia, ranging from 160 to 320 beats/minute, were documented. Five pts, four of whom were less than 1 year old, had syncope or cardiac failure due to tachyarrhythmia. As far as maximum incidence of symptoms is concerned, two peaks were observed: within the first year and between 14 and 16 years of age. A transesophageal electrophysiologic study was performed in 22 pts, tachyarrhythmias were induced in 15, and risk criteria were satisfied in 3/22 (13.6%). Five pts underwent catheter ablation of an accessory pathway and this was successful in three of them. CONCLUSIONS: The clinical course in this series of patients has been benign. Nevertheless, during the first year of life cardiac failure or syncope may occur because of high heart rates. The transesophageal electrophysiologic study, which is also easy to perform in pediatric patients, has been sensitive in assessing the risk of malignant arrhythmia, but it shows low predictive accuracy. Lastly, ablative therapy has shown lower efficacy in children than in adult patients.
The presence of transcripts coding for various alpha and beta subunits of neuronal acetylcholine receptors was investigated using polymerase chain reaction (PCR) on RNA extracted from innervated and denervated adult rat muscles. The results indicate that mRNAs coding for the neuronal alpha 4 and beta 2 subunits are expressed by adult muscles. Unlike avian embryonic muscle tissue, mRNA coding for alpha 7 and beta 4 subunit was undetectable. Denervation did not significantly modify the expression levels of the alpha 4 and beta 2 subunit-specific mRNAs. The results complement our previous immunohistochemical data and suggest that neuronal acetylcholine receptors are expressed by adult muscle tissue and may play a role in the control of muscle function.
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