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Biomedical subjects

L Caputo

Publications and source records attributed to L Caputo.

15 recordsLinked to original sources
PubMed1995

Angiotensin II increases cGMP content via endothelial angiotensin II AT1 subtype receptors in the rat carotid artery.

Angiotensin II (Ang II) has been reported to modulate cGMP formation in various types of cells. To acquire direct information on the intracellular transduction involved in this mechanism, we tested the effects of Ang II on vascular tone and on cGMP content of in vitro isolated carotid arteries from 12-week-old Wistar-Kyoto rats. Segments of carotid artery 20 mm long (n = 8 for each group) maintained at a transmural pressure of 100 mm Hg were immersed in a bath (38 degrees C) containing oxygenated Tyrode's solution. At the end of each experiment, the vessel diameter was measured, and the wall cGMP content was determined by enzyme immunoassay. Under basal conditions, mean diameter was 968 +/- 19 microns, and mean cGMP carotid artery content was 38.9 +/- 3.5 fmol/mg tissue. Incubation for 20 minutes with Ang II (10(-5) mol/L) significantly increased cGMP wall content, twofold above the basal content (P < .01), and constricted the vessel (60 +/- 2.2% of the control diameter, P < .001). After preincubation with a nonselective antagonist of Ang II receptors, saralasin ([Sar1,Val5,Ala8]Ang II, 5 x 10(-5) mol/L), or with a specific antagonist of Ang II AT1 receptor subtype, losartan (5 x 10(-5) mol/L), carotid diameter and cGMP content were no longer affected by Ang II. Exposure of carotid arteries to a specific antagonist of Ang II AT2 receptor, PD 123319 (10(-7) mol/L), modified neither Ang II-induced diameter decrease nor cGMP content increase. Constriction of the vessel with KCl (26 +/- 3%, P < .001) did not modify the basal cGMP wall content.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Endothelial AT1-mediated release of nitric oxide decreases angiotensin II contractions in rat carotid artery.

The purpose of this study was to examine whether angiotensin II (Ang II) stimulates the release of endothelium-derived nitric oxide, which then impairs the contractions of vascular smooth muscle caused by the peptide, and to determine the receptor subtypes mediating these responses. Experiments were performed on isolated rings of rat carotid artery either incubated in the presence of phosphodiesterase inhibitor for the measurement of intracellular levels of cGMP or suspended in organ chambers for recording of changes in isometric force. Ang II (10(-7) mol/L) caused a twofold increase in intracellular cGMP level in preparations with but not in those without endothelium. The presence of endothelium impaired the contractions evoked by the peptide and caused approximately 50% inhibition of the maximal response to Ang II (3 x 10(-8) mol/L); pD2 values for Ang II were 8.9 +/- 0.1 and 9.6 +/- 0.2 in rings with and without endothelium, respectively. In rings with endothelium the contractions to Ang II were augmented by nitro-L-arginine (an inhibitor to nitric oxide synthase) but not indomethacin (an inhibitor of cyclooxygenase), to reach a response comparable to that of preparations without endothelium. In rings without endothelium losartan (a preferential angiotensin type 1 receptor antagonist) displayed competitive antagonism toward Ang II (pA2 = 9.5); PD 123319 (a preferential angiotensin type 2 receptor antagonist; up to 10(-7) mol/L) did not affect the response to the peptide. Losartan (3 x 10(-9) mol/L) but not PD 123319 (10(-7) mol/L) impaired the endothelium-dependent component of the response to the peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1995

Control of carotid vasomotor tone by local renin-angiotensin system in normotensive and spontaneously hypertensive rats. Role of endothelium and flow.

To investigate the relation between the tissue renin-angiotensin system (RAS) and the local vasomotor tone of large arteries, we used in vitro isolated carotid arteries from 14-week-old Wistar-Kyoto rats (WKY; n = 80) and spontaneously hypertensive rats (SHR; n = 80). Diameters were measured with the use of an ultrasonic echo-tracking system (12 MHz) under flow (2 mL/min) (F+) or no-flow (Fo) conditions, with intact endothelium (Endo+) or after endothelium removal (Endo-). The role of tissue RAS was assessed by incubating isolated carotid arteries with an angiotensin-converting enzyme inhibitor (ACE I; lisinopril, 10(-6) mol/L) or with a specific antagonist of angiotensin II AT1 receptors (AT1A; losartan, 10(-6) mol/L). In addition, maximal dilation of carotid arteries was measured after poisoning with KCN (100 mg/L). In all experiments, KCN significantly increased carotid diameters (WKY, 23 +/- 0.9%; SHR, 19 +/- 0.8%; P < .001 versus control conditions). In intact carotid arteries, flow caused significant dilation in WKY (7 +/- 0.5%, P < .001) but had no effect in SHR. In the presence or absence of flow, ACE I and AT1A induced similar dilations in both strains, and a specific antagonist of bradykinin B2 receptors (Hoe 140, 10(-7) mol/L) had no effect on ACE I-induced dilation. After endothelium removal, carotid artery diameters were significantly increased (P < .001) in both strains, although more in SHR (13 +/- 0.8%) than in WKY (8 +/- 1.1%) (P < .001). Also, flow did not modify the diameter of deendothelialized vessels and ACE I had no effect in either strain.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

In vitro assessment of diameter-pressure relationship in carotid arteries from normotensive and spontaneously hypertensive rats.

OBJECTIVE: To compare the mechanical properties of carotid arteries from normotensive and spontaneously hypertensive rats. DESIGN: The pressure-diameter relationships of carotid arteries from nine normotensive adult Wistar-Kyoto (WKY) and nine spontaneously hypertensive rats (SHR) were measured in vitro under control conditions and after poisoning the smooth muscle cells with potassium cyanide. METHODS: Changes in diameter due to changes in transmural pressure were determined with an ultrasonic dimensiometer (12 MHz). The diameter values were determined from the transit times of the pair of echoes given by the proximal and distal walls. The carotid artery was submitted to stepwise increases in pressure of 25 mmHg, from 0 to 200 mmHg; each pressure level was maintained for 5 min before the arterial diameter was recorded. RESULTS: The carotid artery pressure-diameter relationship was a sigmoid curve in both strains. At the same level of pressure, the diameter of the carotid artery from SHR was significantly larger than that from normotensive rats (P < 0.05). Furthermore, the diameter values measured at the operating mean arterial pressure (roughly 100 mmHg for WKY rats and 150 mmHg for SHR) were markedly different (P < 0.001). In both strains, the diameter under passive conditions (with potassium cyanide) was significantly larger than that measured under control conditions (P < 0.01). CONCLUSIONS: Carotid arteries from SHR were significantly stiffer than those from WKY rats. Due to the pressure-dependency of the arterial wall stiffness, the increased arterial stiffness reported in hypertensive rats in vivo is related to an increase in distending arterial pressure and also to a significant reduction in the intrinsic compliance of the arterial wall.

Animals↗
PubMed1992

Iatrogenic bile duct injuries. The real incidence and contributing factors--implications for laparoscopic cholecystectomy.

Laparoscopic cholecystectomy has achieved wide acceptance as the preferred treatment for symptomatic gallbladder disease. Yet there are alarming reports of iatrogenic bile duct injuries. To establish a comparison standard, the incidence of iatrogenic bile duct injury during conventional cholecystectomy has to be known. A single institutional retrospective review of 1,617 consecutive open cholecystectomies between 1980 and 1989 was performed. Eight patients (0.49%) sustained iatrogenic bile duct injury in this study. Inflammation, anatomic variation, or both were contributing factors in all injuries. Operative cholangiography identified the injury at the initial operation in three patients. Treatment consisted of either primary ductal repair, ductal repair over a stent, or ductal-enteric anastomosis. There were no late complications after surgery (follow-up 26 to 97 months; mean 50.9 months). The implications for laparoscopic cholecystectomy are apparent. Iatrogenic bile duct injuries are associated with acute inflammation and/or variant ductal anatomy; routine operative cholangiography assumes increased importance; and immediate repair of the injury minimizes long-term complications.

Acute Disease↗
PubMed1989

The dulling of twist drills during pin channel placement.

Dull twist drills used for pin channels have been cited as an etiology for dentinal cracks. This investigation examined the dulling phenomenon after repeatedly using twist drills. Inspection of the twist drills in the SEM for metal deformation revealed no alteration of the cutting edges but an accumulation of a smear debris was noted behind the cutting edges of the cone-shaped drill. Debris was also recorded on the land and flute spiral surfaces with morphological changes on the dentinal walls. These surfaces progressed serially from a rough surface to a smooth, plaque-like surface with fine striations oriented toward the drill rotation. The timing of the changes coincided with dentinal cracking reported by others. Dulling of twist drills in dentin can be attributed to adherence of byproducts rather than a loss of the cutting edge.

Dental Instruments↗
PubMed1980

Dental pulp mucopolysaccharidase: identification and role in tooth resorption.

The presence of mucopolysaccharidase activity within the pulps of resorbing deciduous teeth was investigated using histochemical techniques. The loss of toluidine blue metachromasia within glycosaminoglycan film subtrates indicated the presence of enzyme activity. This was related to physiologic resorption.

Adolescent↗
PubMed1978

Prevalence of childhood allergy in a subtropical environment: data from Dade County, Florida.

Other prevalence studies of allergy in school children have been limited to temperate zones only. The aims of this computerized investigation were wholly focused on South Florida, located in a subtropical climate. The occurrence of allergy in relation to marked geographic variations was surveyed to evaluate the prevalence of allergy in connection with these topographic differences.

Adolescent↗