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Biomedical subjects

D G Cable

Publications and source records attributed to D G Cable.

30 records · Page 2Linked to original sources
PubMed1997

Endoscopic saphenous vein harvesting: minimally invasive video-assisted saphenectomy.

A technique of greater saphenous vein harvesting for coronary artery revascularization using an endoscopic approach is herein detailed. The saphenous vein is directly identified at the knee through a single incision. An endoscopic dissector is advanced proximally and distally along the course of the vein, ligating side-branches with clips. The vein is divided at the ends of dissection, dependent on patient anatomy, by either a counterincision, endoscopic clips, or ligation with an Endo-loop.

Endoscopy↗
PubMed1997

Expression and function of a recombinant endothelial nitric oxide synthase gene in porcine coronary arteries.

OBJECTIVES: Direct gene transfer of exogenous nitric oxide synthase, with the subsequent increase in nitric oxide production, could represent a potential therapeutic strategy in the treatment of vascular proliferative disorders. The goal of the present study was to determine if porcine coronary arteries could be transduced with an adenoviral vector encoding endothelial nitric oxide synthase (Ad.CMVeNOS) resulting in functional expression. METHODS AND RESULTS: Segments of porcine right coronary artery were exposed for 1 h at 37 degrees C to either replication-deficient adenovirus encoding bovine endothelial nitric oxide synthase (Ad.CMVeNOS, 5 x 10(9) pfu/ml) or control adenovirus encoding Escherichia coli beta-galactosidase (Ad.CMVLacZ, 5 x 10(9) pfu/ml). Immunohistochemistry with a monoclonal antibody specific for nitric oxide synthase (NOS) demonstrated recombinant gene expression in both the endothelial and adventitial layers of Ad.CMVeNOS transduced coronaries with only endogenous NOS confirmed in the endothelium of Ad.CMVLacZ arteries. Coronary arteries transduced with Ad.CMVeNOS yielded 517 +/- 110 (mean +/- S.E.M.) nM/ng nitrite while vessels transduced with Ad.CMVLacZ yielded 126 +/- 84 nM/ng (P < 0.05, n = 6). Isometric tension recording, following prostaglandin F2 alpha constriction, documented a reduced tension in Ad.CMVeNOS transduced coronaries, compared to matched Ad.CMVLacZ coronaries (6.10 +/- 1.08 g vs. 8.45 +/- 1.19 g, respectively, P = 0.05, n = 8). This tension differential was eliminated with prior incubation in NG-monomethyl-L-arginine (L-NMMA, 10(-4) M). The EC50 for calcium ionophore relaxation of Ad.CMVeNOS coronary arteries was reduced compared to Ad.CMVLacZ (-7.90 +/- 0.03 logM vs. -7.26 +/- 0.11 logM, respectively, P < 0.05, n = 8). CONCLUSIONS: These studies demonstrate successful transfer of endothelial nitric oxide synthase into porcine coronary arteries as verified by histochemical localization of recombinant protein with an increase of nitric oxide release as demonstrated by enhanced nitrite production and an alteration in vasomotor function.

Adenoviridae↗
PubMed1997

Pediatric sacrococcygeal chordomas: a rare tumor to be differentiated from sacrococcygeal teratoma.

Sacrococcygeal chordoma is a rare pediatric neoplasm that may be confused with the more common, and indolent, teratoma. The present report describes the diagnosis, treatment and early postoperative convalescence of a case of chordoma in an adolescent child. This case is contrasted to the sacrococcygeal teratoma, a familial pediatric neoplasm, and the literature is reviewed with respect to presentation and treatment.

Bone Neoplasms↗
PubMed1994

Refractory period response of cardiac Purkinje tissue to alpha 1- and alpha 2-adrenergic influences.

Our purpose was to characterize Purkinje responses in vivo to alpha 1- and alpha 2-adrenergic stimulation in sinoaortically denervated and vagotomized dogs pretreated with metoprolol (1 mg/kg). We measured Purkinje relative refractory period (PRRP) responses to norepinephrine (NE) and phenylephrine (PE) with prazosin and/or yohimbine, WB-4101, and chloralethylclonidine (CEC) in varying doses. Results were as follows: PE infusion (25 micrograms.kg-1.min-1) prolonged PRRP (9.6 +/- 1.4 ms; a 4.1 +/- 0.4% change). Prazosin blocked PRRP prolongation with PE at 7 x 10(-8) M/kg (P < 0.05). Yohimbine did not attenuate PRRP prolongation with PE either alone or in combination with prazosin. NE infusion (0.8 micrograms.kg-1.min-1) also prolonged PRRP (9.2 +/- 2.3 ms; a 4.8 +/- 1.0% change). In contrast neither prazosin nor yohimbine at any dose (up to 10(-6) M/kg) totally blocked the prolongation with NE infusion. However, with prazosin (2 x 10(-7) M/kg) pretreatment, yohimbine blocked PRRP prolongation, significant at 7 x 10(-8) M/kg (P < 0.05). In separate experiments with yohimbine pretreatment at 7 x 10(-8) M/kg, PRRP prolongation with either PE or NE infusion was blocked equipotently with WB-4101 and CEC at 7 x 10(-8) M/kg. However, CEC did not block mean arterial pressure (MAP) responses to PE or NE infusion unlike WB-4101. We concluded that both subclasses of alpha 1-adrenergic antagonists equipotently block PRRP prolongation by alpha-agonists despite different effects on MAP. Purkinje refractoriness is also prolonged by alpha 2-adrenergic stimulation acting at the cell membrane.

Adrenergic alpha-Antagonists↗
PubMed1993

Transient depression of responses to sympathetic nerve stimulation overlying a subendocardial infarct.

In previous work, the normal epicardial rim overlying a subendocardial infarct was demonstrated to be parasympathetically denervated. In the present study, we determined responses of effective refractory period (ERP) in this rim during sympathetic nerve stimulation (SNS). Eighteen dogs were studied 1-3 days after a 1-h or permanent coronary artery occlusion (group I). SNS shortened ERP in sites basal, septal, and lateral in the rim by 8 +/- 2, 7 +/- 2, and 7 +/- 2% (SE), respectively, which were similar to sites remote from the infarct (10 +/- 1%). These results were not altered by site of infarction or by atropine administration. To eliminate dissection of the coronary vessel and spontaneous ventricular tachycardia, 19 dogs were studied 6 h after a permanent bead embolization of a coronary artery (group II). In contrast to group I, ERP shortening in the rim sites of group II was depressed (3 +/- 3, 0 +/- 2, and 1 +/- 2%, respectively) compared with remote sites (10 +/- 1%, P < 0.05). In this group, collateral blood flow in the rim was no different than remote epicardium before and during SNS, and norepinephrine shortened ERP in the rim equivalent to remote sites. In an additional 31 animals (group III), the alteration in ATP-dependent K+ channel function was evaluated. Pretreatment with glyburide (an ATP-dependent K+ channel blocker) preserved ERP response to SNS (9 +/- 1% shortening of ERP vs. 12 +/- 2% at baseline) compared with only 3 +/- 0% shortening of ERP with vehicle (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Impulse propagation in the Purkinje system and myocardium of intact dogs.

To characterize Purkinje activation (PA) patterns, we studied 15 alpha-chloralose-anesthetized dogs. During left ventricular basal or apical pacing, PA was mapped with a row of four to eight multipolar electrodes placed in the left ventricular wall to record Purkinje and muscle potentials. PA times increased linearly with distance from the pacing site (r = 0.8, slope 1.8 +/- 0.15 mm/ms, P < 0.05). With a single premature stimulus (S2) delivered from the apical or basal site, delay of PA times was first evident at remote sites (> or = 50 mm) with S1-S2 = 185 +/- 5 (SD) ms, while at peripacing sites (< or = 10 mm), delay was first evident when S1-S2 = 176 +/- 6 ms (Purkinje relative refractory period; P < 0.05). With S2,...S5 such that S1-S2 = S2-S3, and so on, an alternating mode of conduction, both temporally and spatially, occurred. The alternation was due to refractoriness and conduction interactions. With short premature intervals, remote coupling intervals were 30 ms less than the premature intervals. Conduction delay in Purkinje fibers with premature stimuli allowed remote epicardium to be activated by alternate routes. Conduction of constant-rate stimuli in the Purkinje system is relatively uniform. With single premature stimuli, conduction is delayed first remotely from the pacing site, whether apical or basal stimulation was employed. When S1-S2 is less than Purkinje relative refractory period, the usual endocardial-to-epicardial activation sequence is altered. Multiple premature stimuli cause remote coupling intervals to alternate.

Animals↗
PubMed1991

Caring for the terminally ill: communicating with patients and family.

Caring for terminally ill patients requires effective communication skills. It is important that medical personnel understand appropriate ways to communicate with the patient in order to inform him about his illness, throughout its duration. Physicians must develop an understanding of how patients communicate and ways to respond to that communication. Furthermore, the physician needs to communicate with the family of the terminally ill patient. Effective communication must become a regular part of the treatment.

Communication↗
PubMedDate not supplied

Acutely sodded expanded polytetrafluoroethylene grafts produce only prostacyclin: a qualitative difference from saphenous veins.

Select subsets of patients require prosthetic graft material for revascularization. Although arterial prosthetic grafts of large caliber perform acceptably, grafts of <6 mm exhibit a high attrition rate. Microvessel endothelial sodding, a method resulting in the lining of prosthetic grafts with autologous endothelium, improves graft patency; however, aggressive antiplatelet therapy is still required, because terminating an antiplatelet regimen accelerates graft attrition. The present investigation was designed to address the acute production of vasoactive substances in microvessel endothelial cell sodded expanded polytetrafluoroethylene (ePTFE) grafts in an attempt to delineate a possible mechanism behind the continued requirement for antiplatelet therapy. Equal lengths of acutely sodded ePTFE grafts (canine falciform ligament source) and saphenous veins (SV) (canine source) were evaluated by superfusion bioassay. Basal secretion from ePTFE grafts relaxed the biodetector ring 1 +/- 3%, whereas SV relaxed the ring 10 +/- 3% (p < 0.05, ePTFE vs. SV). Relaxation with acetylcholine stimulation was 49 +/- 7% in grafts and 50 +/- 10% in veins (p = NS). Calcium ionophore stimulation produced relaxation of 37 +/- 9% from ePTFE grafts and 100 +/- 23% from SV (p < 0.05). Indomethacin added to perfusate reduced relaxations from sodded ePTFE grafts to 20.2 +/- 9.2% with acetylcholine stimulation and 12.5 +/- 4.3% with calcium ionophore (p < 0.05 vs. control); addition of N(G)-monomethyl-L-arginine (L-NMMA) had no effect on the release of vasoactive substances from ePTFE grafts. In contrast, relaxations of effluent from SV stimulated by acetylcholine and calcium ionophore were significantly attenuated with indomethacin and L-NMMA (p < 0.05 vs. control). Scanning electron microscopy demonstrated confluent endothelium in SV and a nonconfluent endothelial cell layer in grafts. Acutely sodded ePTFE grafts produce vasoactive substances that quantitatively and qualitatively differ from those produced by canine SV. The ePTFE grafts produce mainly prostanoids, whereas SV produce both nitric oxide and prostanoids. The endothelial cell isolation procedure and absence of immediate graft luminal confluence may contribute to the observed differences.

Acetylcholine↗