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Biomedical subjects

J Marco

Publications and source records attributed to J Marco.

At least 127 records · Page 7Linked to original sources
PubMed1993

Morphologic and quantitative study of the efferent vestibular system in the chinchilla: 3-D reconstruction.

An HRP study of the EVN has been performed. Three groups of somas have been identified: Those located in the proximity of the vestibular nuclei, those sandwiched between the facial genu and the IVth ventricle, and those in the RF, surrounding the abducens nucleus. The number of somas is greater in the contralateral brain-stem side. Axons could be followed through the midline, but could not be traced to a labelled soma. A 3-D reconstruction of the EVN within the brain stem is presented.

Animals↗
PubMed1993

Role of an intramammary device in protection against experimentally induced staphylococcal mastitis in ewes.

An intramammary device (IMD) was adapted for use in ewes; this device was made of abraded polyethylene material (1.7 mm in diameter, 47 mm long) and formed a 15-mm-diameter loop in the gland cistern. The IMD was inserted in 1 gland in each of 43 ewes. A significant (P < 0.0001) increase in milk somatic cell count (SCC) was observed in glands provided with an IMD. This increase was attributable to an increase in neutrophil numbers and was observed during the first 12 weeks after insertion. The IMD had a protective effect against experimentally induced staphylococcal mastitis (Staphylococcus aureus and S epidermidis), although different milk SCC were required for protection from each bacterial species in most ewes (10(6) and 2 x 10(5) cells/ml, respectively). Histologic studies revealed that the IMD induced local squamous metaplasia in the glandular part of the lactiferous sinus. Erythrocytes were found in milk from glands provided with an IMD throughout the studied period (35 days of the 45-day lactation) and, in some cases, blood clots were observed during the first 2 weeks of lactation. Glands with IMD also had lower milk production and quality at 30 and 32 days of lactation. Eight ewes with IMD were studied throughout a subsequent lactation. Milk from the IMD-containing glands had an increase in SCC, as in the previous lactation period; did not contain blood clots or erythrocytes; and had normal composition (similar to that in glands without the IMD).

Animals↗
PubMed1993

[Cytomegalovirus gastritis in AIDS: several clues for the diagnosis].

We report a case of a patient with AIDS, CMV gastritis and esophageal candidiasis that presented as epigastric pain resistant to H2-receptor antagonists, and fever. Of interest in this case is the presence of cytomegalic inclusion bodies together with oedema and inflamatory infiltrate on the biopsy specimen of gastric mucosa, whereas on endoscopic examination only mild congestion and thickening of cardial folds were present. A response with Ganciclovir was obtained. We stress the importance of histologic examination for inclusion bodies of endoscopically obtained biopsies as a quick diagnostic procedure. The treatment of the acute phase with Foscarnet and Ganciclovir is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Intracoronary stent implantation: new approach using a monorail system and new large-lumen 7F catheters from the brachial route.

In this brief report we describe a case of successful multivessel PTCA with intracoronary stent implantation using a new large-lumen 7F catheter from the left brachial approach. The application of this technique should be considered for intravascular stent implantation when anticoagulation ideally should not be interrupted or in anatomical situations limiting femoral vascular access.

Angioplasty, Balloon, Coronary↗
PubMed1992

Effects of rat pancreatic polypeptide on islet-cell secretion in the perfused rat pancreas.

Pancreatic polypeptide (PP) secretory cells are abundant in the islets of Langerhans. Results concerning the effects of exogenous PP on islet-cell secretion are controversial. This might be due in part to species specificity, given that most reports refer to studies performed using PP of bovine, porcine, or human origin in a heterologous animal model. Thus, we have investigated the influence of synthetic rat PP (80 nmol/L) on unstimulated insulin, glucagon, and somatostatin release, and on the responses of these hormones to glucose (11 mmol/L) and to arginine (3.5 mmol/L) in a homologous animal model, the perfused rat pancreas. Infusion of rat PP (rPP) reduced unstimulated insulin release by 35% (P = .03), and the insulin responses to glucose by 65% (P = .029) and to arginine by 50% (P = .026), without modifying glucagon output. rPP did not affect somatostatin secretion, either in unstimulated conditions or in the presence of 11 mmol/L glucose. However, it induced a clear-cut increase in somatostatin release during 3.5 mmol/L arginine infusion. Our observation that rPP inhibited insulin secretion without affecting glucagon and somatostatin output points to a direct effect of PP on B-cell function. However, during aminogenic priming of the D cell, the inhibition of insulin output induced by rPP was accompanied by an increase in somatostatin release. Thus, in this circumstance, it might be considered that the blocking effect of PP on B-cell secretion could be, at least in part, mediated by a D-cell paracrine effect.

Animals↗
PubMed1992

Directional atherectomy for treatment of restenosis within coronary stents: clinical, angiographic and histologic results.

OBJECTIVES: The safety and long-term results of directional coronary atherectomy in stented coronary arteries were determined. In addition, tissue studies were performed to characterize the development of restenosis. METHODS: Directional coronary atherectomy was performed in restenosed stents in nine patients (10 procedures) 82 to 1,179 days after stenting. The tissue was assessed for histologic features of restenosis, smooth muscle cell phenotype, markers of cell proliferation and cell density. A control (no stenting) group consisted of 13 patients treated with directional coronary atherectomy for restenosis 14 to 597 days after coronary angioplasty, directional coronary atherectomy or laser intervention. RESULTS: Directional coronary atherectomy procedures within the stent were technically successful with results similar to those of the initial stenting procedure (2.31 +/- 0.38 vs. 2.44 +/- 0.35 mm). Of five patients with angiographic follow-up, three had restenosis requiring reintervention (surgery in two and repeat atherectomy followed by laser angioplasty in one). Intimal hyperplasia was identified in 80% of specimens after stenting and in 77% after coronary angioplasty or atherectomy. In three patients with stenting, 70% to 76% of the intimal cells showed morphologic features of a contractile phenotype by electron microscopy 47 to 185 days after coronary intervention. Evidence of ongoing proliferation (proliferating cell nuclear antigen antibody studies) was absent in all specimens studied. Although wide individual variability was present in the maximal cell density of the intimal hyperplasia, there was a trend toward a reduction in cell density over time. CONCLUSIONS: Although atherectomy is feasible for the treatment of restenosis in stented coronary arteries and initial results are excellent, recurrence of restenosis is common. Intimal hyperplasia is a nonspecific response to injury regardless of the device used and accounts for about 80% of cases of restenosis. Smooth muscle cell proliferation and phenotypic modulation toward a contractile phenotype are early events and largely completed by the time of clinical presentation of restenosis. Restenotic lesions may be predominantly cellular, matrix or a combination at a particular time after a coronary procedure.

Actins↗
PubMed1992

A direct plating method for monitoring the contamination of Listeria monocytogenes in silage.

Twenty-two silage samples were analyzed for the presence of L. monocytogenes using five Listeria selective plating media, with and without previous selective enrichment step. L. monocytogenes was recovered from 3 samples by both procedures, but direct plating allowed the quantification of Listeria population. Two of these positive samples were implicated in outbreaks of listeriosis in sheep; the L. monocytogenes population in these samples was about 10(6) cells/g. The L. monocytogenes population in the other positive sample was 10(3) cells/g. Direct isolation of L. monocytogenes was only possible from LPM, PALCAM and LSAMm media. MOX and LSM media were not selective enough to allow direct Listeria isolation. In our hands, LSAMm was the most suitable plating medium for the direct isolation and specific quantification of L. monocytogenes from silage employing a red blood cells overlay technique.

Animals↗
PubMed1992

[Direct angioplasty without previous fibrinolytic treatment during the 1st hours following myocardial infarction].

Direct coronary angioplasty as an emergency procedure in the first hours of myocardial infarction without prior thrombolytic therapy requires a heavy infrastructure. The different results reported in the literature show a recanalisation rate of 90% with an average hospital mortality of 7%, an acceptable risk given the inclusion of patients of over 75 years of age in these series and cases of cardiogenic shock. The reocclusion rate in the hospital phase is between 10 and 15%. At medium term, the survival rates of single vessel disease are excellent but the mortality is higher in multivessel disease (78% survival at 2 years). Angioplasty performed in the first three hours after the onset of symptoms is associated with an improvement in global an regional left ventricular function in patients with anterior infarction and altered initial left ventricular function. The preliminary results of a randomised multicenter trial comparing direct angioplasty with intravenous thrombolytic therapy with rt-PA (PAMI) seem to show in favour of angioplasty with a lower rate of complications in the hospital phase. The results of this multicenter trial should provide information as to the exact role of direct angioplasty in the initial phase of infarction, a procedure reserved for well-equipped cardiological centres with highly trained invasive cardiologists.

Angioplasty, Balloon, Coronary↗
PubMed1991

Homologous pancreastatin inhibits insulin secretion without affecting glucagon and somatostatin release in the perfused rat pancreas.

The identification of pancreastatin in pancreatic extracts prompted the investigation of its effects on islet cell function. However, in most of the investigations to date, pig pancreastatin was tested in heterologous species. Since there is great interspecies variability in the amino acid sequence of pancreastatin, we have investigated the influence of rat pancreastatin on insulin, glucagon and somatostatin secretion in a homologous animal model, namely the perfused rat pancreas. During 5.5 mM glucose infusion, pancreastatin (40 nM) inhibited insulin secretion (ca. 40%, P less than 0.025) as well as the insulin responses to 10 mM arginine (ca. 50%, P less than 0.025) and to 1 nM vasoactive intestinal polypeptide (ca. 50%; P less than 0.05). Pancreastatin failed to significantly modify glucagon or somatostatin release under any of the above experimental conditions. In addition, a lower pancreastatin concentration (15.7 nM) markedly suppressed the insulin release evoked by 11 mM glucose (ca. 85%, P less than 0.05). Our present observations reinforce the concept that pancreastatin is an effective inhibitor of insulin secretion, influencing the B-cell function directly and not through an A-cell or D-cell paracrine effect.

Animals↗
PubMed1991

Inhibition of insulin release by amylin is not mediated by changes in somatostatin output.

We have investigated the effect of a high concentration (750 nM) of synthetic amidated rat amylin on unstimulated somatostatin and insulin secretion as well as on the response of these hormones to arginine. Amylin consistently reduced insulin output but it did not significantly modify somatostatin release. These findings indicate that the inhibitory effect of amylin on insulin secretion is not mediated by a D-cell paracrine effect.

Amyloid↗
PubMed1991

[A clinical study on the frequency specificity of the 40-hertz potential].

In this paper we introduce the results obtained using 40 Hz potentials, with 500 and 1,000 Hz stimuli, in patients with neurosensory hearing loss, with and without preservation of low frequencies. We analyze the relation latency/intensity, the percentage of presence of the waves and their amplitude.

Acoustic Stimulation↗
PubMed1990

Inhibitory effect of rat amylin on the insulin responses to glucose and arginine in the perfused rat pancreas.

Amylin, a 37-amino acid polypeptide, is the main component of amyloid deposits in the islets of Langerhans, and has been identified in the B-cell secretory granules. We have investigated the effect of rat amylin on the insulin and glucagon release by the isolated, perfused rat pancreas. Amylin infusion at 750 nM, markedly reduced unstimulated insulin release (ca. 50%, P less than 0.025), whereas it did not modify glucagon output. At the same concentration, amylin also blocked the insulin response to 9 mM glucose (ca. 80%, P less than 0.025) without affecting the suppressor effect of glucose on glucagon release. The inhibitory effect of amylin on glucose-induced insulin secretion was confirmed by lowering the amylin concentration (500 nM) and increasing the glucose stimulus (11 mM); again, no effect of amylin on glucagon release was observed. Finally, amylin, at 500 nM, reduced the insulin response to 3.5 mM arginine (ca. 40%, P less than 0.025) without modifying the secretion of glucagon elicited by this amino acid. It can be concluded that, in the rat pancreas, the inhibitory effect of homologous amylin on unstimulated insulin secretion, as well as on the insulin responses to metabolic substrates (glucose and arginine), favours the concept of this novel peptide as a potential diabetogenic agent.

Amyloid↗
PubMed1990

"High-risk" percutaneous transluminal coronary angioplasty with preventive intra-aortic balloon counterpulsation.

Between January 1987 and February 1988, 1,385 patients underwent percutaneous transluminal coronary angioplasty; 27 procedures were performed using prophylactic intraaortic balloon counterpulsation. Twenty-four patients had poor left ventricular function (EF less than 40%), and coronary dilatation was performed in arteries opposite to an occluded myocardial necrosis related vessel. In three patients of advanced age with distal stenoses and normal left ventricular function a multivessel dilatation was performed. Primary success rate was achieved in all patients. There were no deaths, myocardial infarctions or emergency bypass operations in the hospitalization period. During the follow-up (9 to 21 months) there were 2 deaths, 1 cardiac transplantation, and 6 restenosis with repeated dilatation. If revascularization is warranted, in high-risk patients, coronary angioplasty can be performed safely and successfully with protection by intraaortic balloon counterpulsation. However the long-term prognosis of these patients is complicated by the presence of other high-risk variables, such as advanced age or poor left ventricular function.

Age Factors↗