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Biomedical subjects

P W Dillon

Publications and source records attributed to P W Dillon.

At least 37 records · Page 2Linked to original sources
PubMed1995

Pediatric soft tissue infections.

Quite often a soft tissue infection in a child may be the primary reason for seeking medical attention or an incidental finding on examination. To identify those infections that may be serious and require further intervention, all those dedicated to the care of children must be familiar with these illnesses and their complications. This article covers selected bacterial, viral, and fungal infections of the skin, subcutaneous fat, fascia, and muscle. Special considerations for the immunosuppressed child will also be discussed.

AIDS-Related Opportunistic Infections↗
PubMed1994

The extracellular matrix of the fetal wound: hyaluronic acid controls lymphocyte adhesion.

Adhesive interactions between lymphocytes and components of the extracellular matrix (ECM) within a wound environment play a crucial role in determining the inflammatory response following tissue injury. In fetal wounds the extracellular matrix is composed predominantly of hyaluronic acid. Within this environment the inflammatory reaction as a result of injury is minimal. We propose that this lack of an inflammatory cell response in the fetal wound is due to the high levels of hyaluronic acid within the ECM and the inability of lymphocytes to adhere to this matrix component. Therefore, we examined the adhesive properties of fetal lymphocytes to fibronectin, vitronectin, collagen types I, III, IV, V, and hyaluronic acid--ECM components involved in fetal and adult wound environments. Fetal lymphocytes from both spleen and thymus demonstrated significant binding capabilities to fibronectin, vitronectin, and collagen types I and III. No intrinsic binding capabilities were detected to hyaluronic acid. Adhesion was not affected by the addition of IL-1, IFN-gamma, or phorbol dibutyrate. The inability of lymphocytes to adhere to hyaluronic acid helps to explain the lack of inflammation found in fetal wounds and serves to demonstrate the importance of ECM-lymphocyte interactions in determining the inflammatory response during fetal wound healing.

Animals↗
PubMed1994

Endoscopic sphincterotomy in the management of posttraumatic biliary fistula.

Complications after nonoperative management of hepatic trauma are rare but include persistent biliary fistula in 4% of cases. Therapy usually involves surgical drainage or hepatic resection to control the fistula. The authors present a case of hepatic biliary fistula treated nonoperatively with percutaneous drainage and endoscopic sphincterotomy. A 16-year-old girl suffered a grade III parenchymal liver fracture to the right lobe in an automobile accident. She was hemodynamically stable with no coexistent injuries and was treated nonoperatively. Over 2 weeks her total bilirubin rose to 3.2 mg/dL, and alkaline phosphatase was 463 U/L. Ultrasound showed free intraperitoneal fluid, and 2 L of bilious fluid were retrieved by paracentesis. A radionuclide scan confirmed massive extravasation of isotope from the right lobe. Two drains percutaneously placed over the parenchymal fracture produced 500 to 600 mL of bile daily. Endoscopic retrograde cholangiopancreatography (ERCP) 1 week later showed a normal extrahepatic biliary system. A 1-cm sphincterotomy was performed without difficulty. Within 72 hours, percutaneous drains produced only 35 mL per day. The follow-up radionuclide scan showed no evidence of extrahepatic biliary extravasation, and 3 weeks later the drains were removed. Six months after the accident, results of the computerized tomography scan and liver function tests were normal. It was believed that endoscopic sphincterotomy reduced fistula output by decreasing the intrabiliary pressure caused by the ampulla, thus favoring internal drainage. This case demonstrates the effectiveness of endoscopic sphincterotomy as an alternative to direct surgical intervention for the management of posttraumatic biliary fistula.

Accidents, Traffic↗
PubMed1993

Hyaluronate uptake and CD-44 activity in fetal and adult fibroblasts.

One of the unique aspects of fetal wounds is the persistence of a high concentration of hyaluronic acid (HA) in the extracellular matrix. Within the wound environment, both the synthesis and breakdown of this complex glycosaminoglycan are regulated predominately by the fibroblast with cell binding mediated by the membrane receptor CD-44. The ability of adult and fetal fibroblasts to incorporate fluorescent-labeled HA (F-HA) was measured, and the effect of a monoclonal antibody to CD-44 to block this uptake was studied. Fetal fibroblasts incorporated significantly greater F-HA than adult fibroblasts at the 4- and 6-hr times (P < 0.05), while CD-44 blockade reduced the uptake to background levels. These results demonstrate that fetal fibroblasts incorporate F-HA more rapidly than adult fibroblasts and that this uptake is mediated by the membrane protein CD-44.

Aging↗
PubMed1993

Recombinant tissue plasminogen activator for neonatal and pediatric vascular thrombolytic therapy.

Thrombotic vascular occlusion may complicate the clinical course of many neonatal and pediatric pathologic processes. Systemic thrombolytic therapy with heparin, urokinase, or streptokinase may not be appropriate in the critically ill neonate because these agents generate a diffuse coagulopathic state. Direct surgical intervention for repair may be precluded by the small size of the vessels involved. Recombinant tissue plasminogen activator (rTPA) induces only a minimal proteolytic state while inducing thrombolysis within the local environment of the clot. We report our experience with regional rTPA infusion in four critically ill patients with venous and arterial thrombotic disorders. there were two brachial artery occlusive lesions--a neonate with iatrogenic occlusion due to a misplaced intravenous catheter and a 2-year-old child with inadvertent arterial ligation during an attempted venous cutdown. Two venous lesions consisted of a full-term neonate with renal vein/inferior vena caval thrombosis and a 32-week infant with partial superior vena caval thrombosis due to a Broviac catheter. Systemic thrombolytic therapy was contraindicated in these patients because of underlying illnesses. Pretherapy vascular evaluation included Doppler examination and angiography. The rTPA infusion was continued until there was evidence of clot lysis by ultrasound, angiogram, or venogram. Infusion rate of rTPA was adjusted according to fibrinogen levels. All three neonates responded successfully to rTPA therapy. Two neonates required only bolus administration and one responded to combined bolus and continuous infusion therapy after 58 hours. rTPA failed to reverse brachial artery occlusion in the 2-year-old child with purpura fulminans.(ABSTRACT TRUNCATED AT 250 WORDS)

Brachial Artery↗
PubMed1993

Isolated fetal mouse limbs: gestational effects on tissue repair in an unperfused system.

While it is known that adult tissue repair is tightly regulated through local effects in the wound environment mediated by circulating blood elements such as platelets, white cells, cytokines, and hormones, the degree to which each is required in fetal tissue repair is uncertain. This raises the following questions regarding regulation of fetal tissue repair: (1) is the local wound matrix alone sufficient to sustain fetal tissue repair in the same regenerative manner seen in previous in vivo whole animal studies? (2) Will it occur only during the period of rapid fetal growth and development in early and mid gestation? To address these fundamental questions, an organ culture system has been designed to grow isolated, unperfused, developing fetal mouse limbs in a chemically defined, serum-free media. Amputated fetal mouse forelimbs (n > or = 10) were wounded with linear incisions at gestational days 14, 16, and 18 (term = 19); the wounds were closed primarily. These amputated and wounded limbs were placed on steel grids in organ culture petri dishes, then partially submerged in a chemically defined, serum-free media. The limbs were grown at 37 degrees C in humidified 95% air/5% CO2 for 1 week. These wounded limbs were examined histologically at days 0, 3, and 7 postwounding to determine their viability and whether or not tissue repair occurred. In the 14-day group, limb growth and differentiation was evident during the incubation period. Normal dermal and epidermal architecture was restored at the wound site without abundant collagen deposition by day 7 postwounding.(ABSTRACT TRUNCATED AT 250 WORDS)

Amputation, Traumatic↗
PubMed1993

The potential role of the lymphocyte in fetal wound healing.

Wound healing is a complex process involving a number of different cell populations. Since fetal wounds contain only a small number of mononuclear cells and no fibrosis immunohistochemical techniques using monoclonal antibodies specific to T and B lymphocytes, as well as macrophages, were used to identify the mononuclear cells in fetal wounds and to compare the lymphocyte response with the adult wound healing response. Polyvinyl alcohol sponges were placed subcutaneously in fetal rabbits on day 24 of gestation (then 31 days). Adult rabbits underwent similar implantation. Implants (8 to 14 per group) were harvested 5 days later and examined by H&E and trichrome staining as well as immunohistochemical staining with monoclonal antibody (Mab) specific for rabbit T and B lymphocytes. The sponges in one group of fetal rabbits were impregnated with the polypeptide growth factor, transforming growth factor-beta (TGF-beta), a known regulator of adult tissue repair. Adult wounds showed an intense inflammatory response with extensive collagen deposition; 80% of the infiltrating cellular elements were T lymphocytes. Fetal wounds were less cellular with minimal collagen deposition; 40% of the cells were T lymphocytes. The fetal wounds treated with TGF-beta were intensely cellular and fibrotic with 71% of the cellular infiltrate comprised of T lymphocytes. The increased cellularity of the TGF-beta wounds appears to be primarily the result of increased numbers of T lymphocytes. These findings demonstrate that the fetus mounts an attenuated T lymphocyte response compared to the adult. The increased response of T lymphocytes with TGF-beta suggests that the specific growth factor milieu may account for the fetal response to wounding.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Fetal tissue repair and wound healing.

The fibrosis and scar formation that characterize adult wound healing are also the cause of clinical problems; scar contracture, hypertrophic scar, and pulmonary and hepatic fibrosis are only a few examples. Studies of fetal wound healing can provide an insight into the initiation and regulation of a scarless repair process akin to regeneration. Studies of fetal repair have already suggested mechanisms that might favorably alter adult healing. Topical application of hyaluronic acid to wounds in adult diabetic rats leads to enhanced epithelial migration. It has been recognized that the addition of TGF-beta to fetal wounds causes an adultlike healing response with fibrosis and inflammation. A subsequent study using neutralizing antibody to TGF-beta in adult wounds showed enhanced healing with a more normal dermal architecture with fewer macrophages, fewer blood vessels, and less collagen. As our understanding of regenerative tissue repair increases, the opportunities to modulate adult fibrotic conditions should expand.

Adult↗
PubMed1993

Video-assisted thoracoscopic excision of intrathoracic masses in children: report of two cases.

Video-assisted thoracoscopy was used to remove a bronchogenic cyst in a 6-year-old boy and a foregut duplication cyst in a 2-year-old girl. Access ports were placed along the site of a proposed thoracotomy incision and chest tube exit site. Thoracoscopic excision was uneventful, and each child left the hospital on the second postoperative day. Video-assisted thoracoscopy has a role in the evaluation and the definitive treatment of intrathoracic masses in children.

Bronchogenic Cyst↗
PubMed1990

Anatomic and functional abnormalities of the esophagus in infants surviving congenital diaphragmatic hernia.

As more infants with congenital diaphragmatic hernia (CDH) survive by means of extracorporeal membrane oxygenation (ECMO), new clinical observations are being made. We report anatomic and functional abnormalities of the esophagus in these infants. Twenty-two of 30 infants with CDH survived. Three of 7 non-ECMO-treated infants and 14 of 17 ECMO-treated infants had an air- or fluid-filled mediastinal mass that was confirmed by an upper gastrointestinal series as ectatic esophagus. Contrast studies demonstrated severe gastroesophageal reflux. Intra-esophageal pH monitoring confirmed significant reflux (Euler scores greater than 50) in 69% of tested patients. Prolonged acid clearance in most patients implied abnormal peristalsis. Hydramnios was correlated to the observed esophageal abnormalities, being present in 13 of 16 infants with an available amniotic history. All patients had symptomatic gastroesophageal reflux managed without antireflux surgery and were discharged 36 +/- 2 days after initiation of feeding. Follow-up (range: 7 to 56 months; mean: 32 months) showed that weight gain in affected children was slower than in those not affected. All but one are asymptomatic. Repeat upper gastrointestinal series shows persistent ectasia but less gastro-esophageal reflux. Gastroesophageal reflux/ectasia is a new observation with CDH. The associated hydramnios may result from proximal foregut obstruction by kinking the gastroesophageal junction with CDH. The radiographic appearance can be quite unusual. Clinical manifestations of gastro-esophageal reflux are manageable without surgery but may account for the observed compromised growth.

Dilatation, Pathologic↗
PubMed1990

Modification of cardiopulmonary hemodynamics and vasoactive mediators by extracorporeal membrane oxygenation in newborn lambs.

We asked if prolonged venoarterial extracorporeal membrane oxygenation (ECMO) causes alterations in cardiopulmonary hemodynamics that might be reflected in arbiters of vascular tone: thromboxane, prostacylin, norepinephrine, and epinephrine. Newborn lambs undergoing ECMO demonstrated significant augmentation of systemic and pulmonary arterial blood pressure that was temporally related to rises in all vasoactive mediators measured. Although the prostanoids returned to baseline within 30 minutes, the catecholamines remained elevated significantly throughout bypass. Long-term bypass, however, was not associated with sustained systemic hypertension. Pulmonary hypertension was achieved only after 6 hours of bypass. These acute and chronic changes may exacerbate a pathological state for which ECMO is indicated.

Animals↗
PubMed1988

Esophageal dilatation and reflux in neonates supported by ECMO after diaphragmatic hernia repair.

Extracorporeal membrane oxygenation (ECMO) for survivors of surgical repair of congenital diaphragmatic hernia was used in 14 neonates. All showed marked esophageal dilatation on postoperative chest radiographs; the dilated esophagus simulated an air- or fluid-filled mass. All patients were later shown to have marked gastroesophageal reflux as well. The finding suggests a problem in swallowing exists before birth, which may explain the recent correlation between diaphragmatic hernia and hydramnios. The observation of a mediastinal mass in neonates with congenital diaphragmatic hernia may represent esophageal ectasia and may be related to significant gastroesophageal reflux.

Dilatation, Pathologic↗
PubMed1987

Extracorporeal membrane oxygenation for neonatal respiratory failure.

Extracorporeal membrane oxygenation will continue to be an appropriate modality of treatment in properly selected infants. In the future, respiratory management and selection criteria for these patients should become standardized and universally accepted. It is conceivable that as we become more comfortable with this treatment we can complete prospective, randomized trials on infants who have less than a 90 percent mortality likelihood and thereby avoid the ethical implications of a study in which the control population has death as an endpoint. It is also conceivable that ECMO will be more benign and induce less morbidity than the barotrauma seen in many of the infants supported by aggressive ventilator management.

Humans↗
PubMed1985

Extracorporeal membrane oxygenation and congenital diaphragmatic hernia: modification of the pulmonary vasoactive profile.

We studied the vasoactive profile of a term infant with congenital diaphragmatic hernia and intractable pulmonary hypertension who was refractory to conventional medical management despite an early stable period. Plasma prostanoid vasoconstrictor thromboxane A2 (TxB2) levels were elevated prior to ECMO at 150pg/mL, rose to 310pg/mL with the first hour of bypass and remained elevated until 72 hours by which time they fell to less than 50pg/mL. This coincided with the decreased extracorporeal circulatory support needed to maintain systemic arterial pO2 between 70 to 90 torr. Pulmonary vasodilator prostacyclin (6-keto-PGF1 alpha) was minimally elevated prior to bypass a 50pg/mL and became undetectable. Catecholamine levels were markedly elevated prior to ECMO at 4,000pg/mL with no demonstrable pulmonary extraction of norepinephrine. Though catecholamine levels remained nonspecifically elevated, pulmonary metabolism of norepinephrine improved with bypass time to 48% at 96 hours and coincided with the overall improvement of the infant's respiratory function. These data suggest pulmonary hypertension associated with congenital diaphragmatic hernia is at least partially precipitated by alterations in prostanoid homeostasis as selective activation of thromboxane synthetase pathways rather than nonspecific activation of the entire archidonate cascade. While ECMO per se may have no lasting effect on prostanoid homeostasis, ECMO can allow a period of cardiopulmonary rest during which more physiologic prostanoid levels are established. Although activation of the sympatho-adrenal axis may contribute to pulmonary hypertension, the role of catecholamines in this infant is not clear. Return of the lungs ability to clear norepinephrine may be an additional marker of biologic lung recovery.

6-Ketoprostaglandin F1 alpha↗