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Biomedical subjects

R Berguer

Publications and source records attributed to R Berguer.

At least 55 records · Page 3Linked to original sources
PubMed1995

Differential production of intracellular gamma interferon in alpha beta and gamma delta T-cell subpopulations in response to peritonitis.

Flow cytometry was used to measure T-cell intracellular gamma interferon and surface interleukin 2 re-ceptor expression in response to peritonitis in rats. Interleukin 2 receptor expression levels were similar in the two T-cell subsets, but gamma interferon production was increased fivefold in gamma delta T cells compared with pro-duction in alpha beta T cells. Our results provide further evidence of an early and vigorous gamma delta T-cell response to bac-terial infection.

Animals↗
PubMed1994

Laparoscopic colon surgery in a rat model. A preliminary report.

The effects of laparoscopic colectomy on immune function require further study. Because the rat has been widely used to investigate the immune system we studied the feasibility of laparoscopic sutured colon anastomoses in a rat model. We used a low-pressure CO2 pneumoperitoneum, a 2.7-mm 30 degree wide-angle arthroscope and video system, and microotologic forceps and scissors to perform two-handed dissection and suturing of the rat colon. The procedures included laparoscopic division of the colon and colostomy (group A, n = 3), laparoscopic closure of a colotomy (group B, n = 4), and complete laparoscopic division and reanastomosis of the colon (group C, n = 4). One anesthetic death occurred in group C. Necropsy performed 1-15 days postoperatively revealed no anastomotic leaks and two anastomotic strictures. Laparoscopic sutured colon anastomosis in the rat is feasible and may provide a new model for the physiologic study of laparoscopic colon surgery.

Anastomosis, Surgical↗
PubMed1994

Revascularization by the retropharyngeal route for extensive disease of the extracranial arteries.

PURPOSE: This is a retrospective study of 16 patients who had an average of 3.25 arteries supplying the brain that were occluded or severely diseased. In all of them severe disease or occlusion of the left carotid and subclavian arteries precluded an ipsilateral repair. METHODS: These patients with extensive extracranial arterial disease underwent revascularization from the opposite side of the neck through a retropharyngeal tunnel. Twelve patients had contraindications for a transthoracic repair. RESULTS: There were no early deaths. Postoperative complications included one graft occlusion, one anastomotic disruption with hemorrhage, and one stroke, all resulting from management errors. Follow-up was 100%. Primary patency rate was 94%, and survival was 87.5%. Two patients died in the interval: one from a myocardial infarction and one from cause unknown. CONCLUSIONS: The retropharyngeal route is a shorter and more direct path across the neck and occasionally permits direct carotid-to-carotid transposition without the use of prosthetic bypasses. Even in the presence of extensive extracranial disease, these reconstructions have an excellent patency rate, and these patients have a survival 87.5% after a mean follow-up of 5.56 +/- 4.0 years.

Adult↗
PubMed1994

Carotid artery reconstruction using superficial femoral arterial grafts.

The indications, consequences, and value of resection of the carotid artery as part of an extended neck dissection has been discussed for many years. Many of the earlier reports have focused on the sequelae of carotid artery ligation and tests to predict patient tolerance for the procedure. Efforts to reconstruct the carotid artery have been limited primarily to vein grafts. The authors report on 11 cases of reconstruction of the carotid artery using the patient's superficial femoral artery. The femoral artery itself is reconstructed using a Gore-Tex graft. Free autografts of the superficial femoral artery in the carotid location have been found to be an excellent size match, mechanically stronger than a vein graft, and tolerant of bacterial contamination. Arteriography in 1 case with 14 months' follow-up demonstrates long-term patency.

Blood Vessel Prosthesis↗
PubMed1993

Bradykinin-induced mesenteric vasodilation is mediated by B2-subtype receptors and nitric oxide.

We investigated mechanisms mediating bradykinin (BK)-induced anterior mesenteric artery (AMA) vasodilation in anesthetized rats. The velocity of blood flowing (VBF) in the AMA was measured with pulsed Doppler velocimetry, and arterial pressure (BP) was measured with a pressure transducer. Drugs were infused through an intra-aortic catheter positioned proximal to the AMA origin. AMA conductance (C) was calculated from mean VBF/BP and expressed as percent of control C. BK infusion (10-1,000 ng.kg-1.min-1) increased C significantly (Cmax = 201 +/- 18%, ED50 = 100 ng.kg-1.min-1, P < 0.01 for all doses). A B2-subtype receptor antagonist, D-Arg,[Hyp3,Thi5.8,D-Phe7]BK, administered at 10(5) ng.kg-1.min-1 before or during BK infusion, inhibited the vasodilation by 73 +/- 7 and 103 +/- 7%, respectively. A nitric oxide (NO) synthesis inhibitor, NG-nitro-L-arginine, administered at 5.0 mg/kg 15 min before BK, inhibited the hyperemia by 61 +/- 8%. Neither a B1-receptor antagonist nor intrajejunal capsaicin inhibited BK-induced vasodilation. BK-evoked, dose-dependent, mesenteric vasodilation in rats appears to be mediated partly by B2-receptors and endogenous NO generation.

Animals↗
PubMed1993

Is bradykinin (BK) a physiological vasodilator in the gut?

The physiological role of bradykinin (BK) as a mesenteric vasoregulator was explored. This nonapeptide is a potent vasodilator substance when administered exogenously in multiple in vivo models and is a smooth muscle relaxant when added to in vitro preparations. BK is naturally occurring in the gut wall. The substrate for BK, as well as the biosynthetic and metabolizing systems are present in the blood, the vascular wall, immunological cells, and perivascular neurons. BK B2 and B1 receptors have been characterized with sympathetic agonist and antagonist substances, and the receptors are present on mesenteric endothelial cells and myocytes. BK interacts with multiple endogenous mesenteric vasodilator mediators, such as nitric oxide, prostacyclin, and neuropeptides. Taken together this evidence supports the functional importance of BK as a normal vasodilator in the gut.

Amino Acid Sequence↗
PubMed1993

[Laparoscopic surgery in the rat: description of a new technique].

We report a method of laparoscopic surgery in the rat. Our technique is illustrated by gastric fundoplication requiring two handed dissection, suturing, and knot tying. This animal model for laparoscopic surgery is relatively inexpensive, can be extended to other operations, and makes use of an extensively studied animal. These factors may facilitate investigation of the physiologic effects of minimal access surgery.

Animals↗
PubMed1992

Selective deep hypothermia of the spinal cord prevents paraplegia after aortic cross-clamping in the dog model.

We tested, in the dog, the hypothesis that selective deep hypothermia (19 degrees to 12 degrees C) of the spinal cord protects it from the ischemia that follows double aortic cross-clamping. The extracorporal perfusion system consisted of heat exchanger and a pump, infusing saline solution at 5 degrees C into the subarachnoid space (L-6) and draining it through the cisterna magna. After 30 minutes this system cools a normally perfused spinal cord to a stable temperature gradient of 13 degrees C (inflow) to 18 degrees C (outflow). Proximal and distal intrathecal, proximal and distal aortic, and central venous pressures were continuously recorded. Rectal temperature was maintained between 36.5 degrees C and 38.5 degrees C. Eight control dogs had cross-clamping of the aorta below the left subclavian artery and above the diaphragm without cord hypothermia. Nine experimental dogs had cord hypothermia initiated 50 minutes before systemic heparinization (100 U/kg) and double cross-clamping of the aorta. Cross-clamping was maintained for 45 minutes. The aorta was then unclamped, heparin was reversed, cord cooling was discontinued, and the dura was closed. Hindlimb function of animals was graded by use of Tarlov's scale at recovery and 24 hours later. The dogs were then killed, and the cords were removed and fixed for microscopy. All control animals were paraplegic and had histologic confirmation of spinal cord infarction. All experimental animals had intact hindlimb function and normal appearing cords on histologic examination. A two-tailed Fisher's exact test (chi square) shows this difference to be significant to p = 0.00004. In the dog selective deep hypothermia of the cord avoids the ischemic injury induced by aortic cross-clamping that results in paraplegia. The implications of these findings in thoracoabdominal aortic clamping in humans is discussed.

Animals↗
PubMed1991

Minimal access surgery for gastroesophageal reflux: laparoscopic placement of the Angelchik prosthesis in pigs.

Conventional surgery for gastroesophageal reflux is effective but requires laparotomy. Minimal access surgery for gastroesophageal reflux could provide a decrease in morbidity. The Angelchik antireflux prosthesis is an alternative to fundoplication for the treatment of this ailment. We evaluated the results of laparoscopic placement of the Angelchik prosthesis in 10 pigs. The duration of the procedure averaged 44 min. The mean lower esophageal sphincter pressure increased from 12.2 +/- 2.8 mmHg at baseline to 45.2 +/- 7.8 (P less than 0.05), 32.1 +/- 3.9 (P less than 0.05), and 25.1 +/- 6.5 mmHg (P greater than 0.05) as measured immediately postoperatively, at 1 week, and at 3 weeks, respectively, following placement of the prosthesis. There was no instance of prosthetic migration or esophageal perforation. One postoperative death due to distention and perforation of the colon occurred. Two animals developed distal esophageal impaction of food. We conclude that the antireflux prosthesis can be safely and effectively placed using laparoscopic methods in a porcine model. Further development of this technique is warranted.

Animals↗
PubMed1991

Beneficial effects of isovolemic hemodilution using a perfluorocarbon emulsion in a stroke model.

In a clinically applicable cat stroke model, 16 purpose-bred adult animals were used to evaluate the beneficial effects of two treatment regimens: isovolemic hemodilution with either a perfluorocarbon emulsion or dextran 40 (a glucose polymer). Animals that received these treatment regimens were then compared with a control group of untreated animals. Focal cerebral infarctions were produced by transorbital ligation of the left middle cerebral artery. The randomly allocated treatment arms of the study were instituted 3 hours after ligation of the middle cerebral artery, thereby simulating a human clinical situation. In vivo mitochondrial metabolic activity of the peri-infarct cerebral tissue was continually assessed by means of a multiwavelength near-infrared spectrophotometer. This allowed measurement of cellular oxygenation at the cytochrome aa3 level, the terminal member of the cytochrome chain. Sequential proton-based magnetic resonance imaging was used to measure intracerebral water in vivo. Cardiac output, oxygen consumption/delivery, chemical, histologic, and rheologic parameters were also assessed. The data collected were analyzed by group means and standard statistical analyses, which revealed that the group treated with the perfluorocarbon emulsion had both less brain edema in the early post-infarct period (p less than 0.05), as well as a higher level of oxidation of cytochrome aa3 (p less than or equal to 0.025). This evidence supports the premise that isovolemic hemodilution with an oxygen-carrying hemodiluent may be beneficial in the treatment of ischemic strokes.

Animals↗
PubMed1990

MRI quantitation of edema in focal cerebral ischemia in cats: correlation with cytochrome aa3 oxidation state.

1H MRI permits detection of edema in the brain. In a middle cerebral artery stroke model in the cat, we found a significant correlation between an edema index based on MRI and a sensitive metabolic index of ischemia, the in vivo oxidation status of mitochondrial cytochrome aa3 determined by near-infrared reflectance spectrophotometry (r = -0.70, alpha = 0.001). This result suggests that a simple, noninvasive study using MRI can provide an index of the extent of ischemic damage in an experimental acute stroke model.

Animals↗
PubMed1988

Determinants of porphyrin fluorescence emission spectra of atheromatous plaques.

Plaques were obtained via carotid endarterectomy and exposed to the fluorescent dye hematoporphyrin in vitro. Fluorescence emission spectra were used to characterize sites of dye binding. To provide additional information on the role of environment on fluorescence, model systems were studied involving micellar and premicellar systems. The data indicate two distinct fluorescence signals from plaque-bound porphyrin. These signals were at least 50-fold greater than the fluorescence from uninvolved regions of the vessel wall. Fluorescence emission at 618 nm was observed in all plaques examined. A second fluorescence signal at longer wavelengths was associated with the more complex plaques and could be mimicked by mixtures of porphyrin and detergent at a premicellar concentration. These studies suggest the presence of 2 different porphyrin-binding regions in the plaques examined. The first appears to be a predominantly aqueous site which may represent the interior of a cholesterol-rich micellar structure. The second is associated with 'hard' plaque, i.e., collagen and calcification.

Arteriosclerosis↗
PubMed1986

The short retropharyngeal route for arterial bypass across the neck.

Occasionally, in order to revascularize the carotid bifurcation one may need to cross the neck with a bypass that originates in the opposite subclavian or common carotid artery. This report describes a short, natural route behind the pharynx that permits using a shorter bypass as well as a direct reimplantation of one common carotid into its opposite without an intervening graft.

Arterial Occlusive Diseases↗