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Biomedical subjects

L M Marmon

Publications and source records attributed to L M Marmon.

15 recordsLinked to original sources
PubMed1995

The interaction between endothelium-derived relaxing factor (EDRF) and eicosanoids in the regulation of the mesenteric microcirculation.

Locally produced eicosanoids and endothelium-derived factors are believed to be the mediators of vascular tone of various vascular beds including the mesentery. Using a small vessel isometric myograph which allows direct measurement of microvascular reactivity, the interaction of eicosanoids and endothelium-derived relaxing factor (EDRF) in regulating vascular tone of mesenteric microcirculation of the rat was characterized. The microvascular response to various vasoactive agents before and after inhibition of prostacyclin production with indomethacin (INDO, 5 microM) and inhibition of EDRF synthesis with N omega-nitro-L-arginine methyl ester (L-NAME, 50 microM) was compared. Analysis of dose-response curves for prostaglandin F2 alpha (PGF2 alpha), U46619, a stable thromboxane analog, and norepinephrine (NE) after pretreatment with INDO demonstrated that inhibition of endogenous eicosanoids significantly attenuated the vasoconstrictor response to PGF2 alpha and U46619 but not to NE. Inhibition of EDRF synthesis with L-NAME potentiated the vasoconstrictor response to PGF2 alpha, U46619, and NE. These results suggest that EDRF acts as the primary mediator of vasodilator tone in the mesenteric microcirculation rather than vasodilator cyclooxygenase products such as prostacyclin. It also appears that the vasoconstrictor action of PGF2 alpha and U46619 may be mediated by a release of an endogenous indomethacin-sensitive factor.

Animals↗
PubMed1993

Identification of dopamine1A receptors in the rat small intestine.

Dopamine receptors have been localized to several tissues outside the central nervous system including the kidney and mesenteric vessels. To determine if there are dopamine1 receptors within the small intestine, homogenates of the antimesenteric halves of the entire jejunum and ileum of adult rats were prepared and competitive inhibition studies and Scatchard analysis were performed at room temperature using 125I-SCH 23982 and SCH 23390. The specific binding of 125I-SCH 23982 to the intestinal tissue homogenates was rapid, saturable with ligand concentration, and reversible. Analysis of the Scatchard plots revealed a single class of receptors with an apparent dissociation constant of 10.77 +/- 2.32 nM and maximum receptor density of 1.37 +/- 0.34 fmole/mg protein. Emulsion autoradiography performed using 125I-SCH 23982 on antimesenteric sections of the rat small intestine revealed that the dopamine1 receptors are located on cells at the base of the intestinal crypts. Two dopamine1 subtypes (D1A and D1B) have been identified by molecular biological techniques. Using a ribonuclease protection assay we found expression of the D1A receptor gene in the small intestinal tissue. These studies are the first to identify, characterize, and localize receptors for the endogenous catecholamine, dopamine, within the rat small intestine and to confirm the expression of the D1A receptor gene.

Animals↗
PubMed1992

Successful splenorenal shunt for emergent control of variceal bleeding in a small child.

A 8.6-kg, 10-month-old boy with idiopathic cavernous transformation of the portal vein developed variceal hemorrhage refractory to nonoperative management. A distal splenorenal shunt was performed while the bleeding was controlled with balloon tamponade. Hemorrhage was successfully controlled with no recurrent bleeding and the shunt remains patent at 1 year of follow-up.

Esophageal and Gastric Varices↗
PubMed1991

Laparoscopic cholecystectomy in pediatric patients.

Laparoscopic cholecystectomy has gained increasing application as an operative approach for adults with gallbladder disease. We assessed the safety and feasibility of this technique in five pediatric patients with symptomatic cholelithiasis, two of whom had sickle cell disease. With several technical modifications, we found that laparoscopic cholecystectomy was safe and effective in children. This technique permitted early discharge with expedient return to full activity.

Adolescent↗
PubMed1990

Thymolipoma: computed tomographic appearances.

The computed tomographic (CT) appearances of a thymolipoma are described in a 5 1/2-year-old girl. The location and CT appearances of the tumor appear to be specific for the diagnosis of thymolipoma.

Child, Preschool↗
PubMed1985

Evaluation of absorbable polyglycolic acid mesh as a wound support.

The ideal wound-support material would reinforce a wound early in the healing process when intrinsic wound strength is the weakest, yet disappear over time, preventing many of the untoward late effects seen with currently utilized nonabsorbable materials. This study was designed to evaluate the effectiveness of a newly designed absorbable material, polyglycolic acid mesh (Dexon), as a buttress for abdominal wounds closed under moderate tension. Young male rats (n = 211) were divided into three experimental groups. Animals in groups 1 (n = 96) and 2 (n = 95) had a 1.2 cm2 midline abdominal wall defect created and closely primarily. Animals in group 2 had a 2 X 5 cm piece of polyglycolic acid mesh sutured to the anterior abdominal wall overlying the closed abdominal defect. Animals in group 3 (n = 20) were unoperated controls. The animals in groups 1 and 2 were killed 1, 2, 3, 4, and 5 weeks after surgery. The entire anterior abdominal wall was removed and placed upon a bursting strength testing device. Bursting strength determinations of the supported and unsupported abdominal closures revealed that the strength of the wounds reinforced with polyglycolic acid mesh was significantly greater than unsupported wounds at 1, 2, and 3 weeks after surgery. Wounds supported with mesh had bursting strengths similar to unoperated abdomens by the first postoperative week. This study demonstrates that abdominal wall defects in rats closed primarily develop increased wound strength when the closure is supported by absorbable polyglycolic acid mesh. The use of an absorbable material may alleviate potential late complications associated with implantation of nonabsorbable materials. The clinical application of such a material remains to be determined.

Abdominal Muscles↗
PubMed1984

Congenital cardiac anomalies associated with the DiGeorge syndrome: a neonatal experience.

The DiGeorge syndrome is a rare congenital abnormality of absent of hypoplastic thymus and parathyroid glands. Thirty neonates who had cardiac lesions and the DiGeorge syndrome are reviewed. The early mortality for 10 neonates undergoing palliative procedures was 80%. Seventy-five percent of the deaths were secondary to sepsis. Twenty neonates did not undergo palliative procedures. In this group, early mortality was 60% and late mortality was 65%. Sixty percent of the deaths in this group were associated with sepsis, with cardiac failure responsible for the remaining deaths. Survival in both groups has improved with appropriate treatment of the immunological and metabolic consequences of the DiGeorge syndrome.

Abnormalities, Multiple↗
PubMed1984

Vascular rings and slings: long-term follow-up of pulmonary function.

Between 1968 and 1983, 54 patients underwent surgery for symptomatic aortic arch and pulmonary artery anomalies at St Christopher's Hospital for Children. Presenting symptoms included stridor, wheeze, apnea, recurrent pulmonary infections, or dysphagia. Diagnosis was established with chest roentgenogram, bronchoscopy, barium esophagram, and arteriography. Four types of vascular anomalies were encountered; double aortic arch (24 patients), right aortic arch with left ligamentum arteriosum (17 patients), anomalous innominate artery (10 patients), and pulmonary artery sling (three patients). There were no intraoperative deaths and only one postoperative death. All surviving patients had immediate relief of their severe respiratory or swallowing symptoms. Mild respiratory symptoms persisted postoperatively from 3 months to 4 years and included frequent or severe upper respiratory infections, persistent cough, stridor and pneumonia. Five of the 53 surviving patients were lost to follow up. The remaining 48 patients were followed from 6 months to 14 years and all but one patient noted complete resolution of all respiratory symptoms. Twenty-nine patients at follow up were old enough to undergo pulmonary function testing including vital capacity, functional residual capacity, and inspiratory and expiratory flow volume loops. Seventeen of these 29 asymptomatic patients consented to these studies, and nine of these patients had abnormal flow volume loops indicative of significant central airway obstruction; the other eight studies were normal. We conclude that surgical repair for vascular rings and slings is safe and symptomatically efficacious. However, anatomic tracheal or bronchial distortion persists in a significant number of these patients as evaluated by pulmonary function studies.

Adolescent↗