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Biomedical subjects

N J Thomas

Publications and source records attributed to N J Thomas.

34 records · Page 2Linked to original sources
PubMed1998

Hypovolemic shock in pediatric patients.

Hypovolemic shock is a common disease treated in pediatric ICUs and emergency departments worldwide. A wide variety of etiologic factors may cause this disease, with the common net result of decreased intravascular volume leading to decreased venous return to the heart and decreased stroke volume. Inadequate perfusion results in impairment of delivery of nutrients and oxygen to vital end organs. With the advent of pediatric critical care and pediatric emergency medicine as specialties, deaths from hypovolemic shock have become increasingly rare in the United States. The physical signs of hypovolemic shock in children must be quickly recognized, and aggressive volume resuscitation must be administered before irreversible end-organ dysfunction occurs. This is best accomplished by large peripheral or central intravenous access, with intraosseous access an alternative option in the pediatric patient. The amount as well as the type of volume administered must be tailored for each individual patient, taking into account the amount of intravascular depletion and the disease state in which the shock has occurred. It is not uncommon for children to require large amounts of fluid for resuscitation, and close attention must be paid to children with fluid-refractory shock, who may require catecholamine and/or exogenous steroid support in combination with aggressive fluid resuscitation.

Adolescent↗
PubMed1997

Pediatric ECMO for severe quinidine cardiotoxicity.

We report the use of extracorporeal membrane oxygenation (ECMO) to establish and maintain cardiovascular stability in a 16 month old with refractory bradydysrrhythmias and hypotension after an acute overdose of quinidine. He underwent an 11-day course of ECMO and was discharged with normal neurologic function. This case illustrates the role ECMO can play in the treatment of profound cardiovascular collapse caused by toxic ingestions. To be optimally effective, management of such patients must be anticipatory.

Anti-Arrhythmia Agents↗
PubMed1997

DDE poisoning in an adult Bald eagle.

A 12-year-old female bald eagle (Haliaeetus leucocephalus) was found in May 1993 on Santa Catalina Island, California (USA), in a debilitated condition, exhibiting ataxia and tremors; it died within hours. On necropsy, the bird was emaciated but had no evidence of disease or physical injury. Chemical analyses were negative for organophosphorus pesticides and lead poisoning. High concentrations of DDE (wet weight basis) were found in the brain (212 ppm), liver (838 ppm), and serum (53 ppm). Mobilization of DDE, from depleted fat deposits, probably resulted in the lethal concentration in the eagle's brain.

Adipose Tissue↗
PubMed1996

Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats treated with norepinephrine.

We recently reported that pretreatment with the type IV phosphodiesterase inhibitor Ro 20-1724 attenuates the development of endotoxin-induced acute renal failure in rats. Norepinephrine is an important therapeutic agent in human endotoxemia, but its efficacy is limited by its deleterious side effect of potent renal and mesenteric vasoconstriction. In this study we examined whether posttreatment with Ro 20-1724 after endotoxin infusion 1) attenuates increased renal vascular resistance and the development of acute renal failure in the absence and presence of norepinephrine infusion, 2) improves mesenteric blood flow in the presence of norepinephrine and 3) improves survival rates in the absence and presence of norepinephrine infusion. Forty-eight rats were anesthetized and instrumented, and eight 20-min clearance periods were performed. Endotoxin (20 mg/kg i.v.) was administered after the first period, and a constant-rate i.v. infusion of either Ro 20-1724 (10 micrograms/kg/min) or vehicle was initiated after period 3, in the absence and presence of norepinephrine infusion (1 microgram/kg/ min, begun after period 4). Urinary cAMP excretion in the Ro 20-1724-treated groups was 2- to 3-fold (P < .001) higher, compared with the vehicle-treated groups. Ro 20-1724 markedly attenuated endotoxin-induced (P < .01) increases in renal vascular resistance and attenuated norepinephrine-induced (P < .05) increases in renal vascular resistance in rats pretreated with endotoxin. Moreover, Ro 20-1724 reduced endotoxin-induced decreases in renal blood flow (P < .05) and glomerular filtration rate (P < .01) in the absence and presence of norepinephrine. In animals pretreated with endotoxin, Ro 20-1724 attenuated norepinephrine-induced increases in mesenteric vascular resistance (P = .054) and decreases in mesenteric blood flow (P < .01). Ro 20-1724 also improved survival rates for endotoxin-treated rats, whether or not the rats were administered norepinephrine (P < .01). Type IV-specific phosphodiesterase inhibitors warrant further study as selective therapeutic agents that protect against endotoxin/vasopressor-induced renal and mesenteric ischemia and death.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1995

Hypopi (Acari: Hypoderatidae) of the wood stork (Aves: Ciconiiformes; Ciconiidae).

A new species is described and additional host records are presented for 2 other species of deutonymphs of the family Hypoderatidae from the subcutaneous adipose tissues of the wood stork, Mycteria americana L. Phalacrodectes (Phalacrodectes) mycteria n. sp. appears to share affinities with species from both pelicaniform and ciconiiform hosts, but it most closely resembles P. (P.) punctatissimus (Cerný) Pence & Courtney from pelicans in idiosomal chaetotaxy, cuticular sclerotization, and posteriorly divergent, widely separated genital openings. The new species differs from this and other species of the genus by its small size, the degree of separation of the genital openings with papillae, no secondary sclerotization in the perigenital area or surrounding the genital openings, and the long filiform setae s and w on genu III. There was a mixed infection of Neottialges kutzeri Fain and N. mycteriae Pence in all of 7 wood storks examined from Florida and Georgia; P. (P.) mycteria was found in 4 of these hosts. This is the 7th species described as a deutonymph in the genus Phalacrodectes. The apparent close affinity of P. (P.) mycteria with P. (P.) punctatissimus and allied species from pelicaniform versus ciconiiform birds appears to be inconsistent with the established host-parasite relationships based on classical avian taxonomic relationships. However, this apparent affinity may be more reflective of the close relationships between the families of pelicans, ibises and spoonbills, and storks as recently proposed by DNA-DNA hybridization studies.

Animals↗
PubMed1995

Application of brain cholinesterase reactivation to differentiate between organophosphorus and carbamate pesticide exposure in wild birds.

Brain cholinesterase activity was measured to evaluate pesticide exposure in wild birds. Thermal reactivation of brain cholinesterase was used to differentiate between carbamate and organophosphorus pesticide exposure. Brain cholinesterase activity was compared with gas chromatography and mass spectrometry of stomach contents. Pesticides were identified and confirmed in 86 of 102 incidents of mortality from 29 states within the USA from 1986 through 1991. Thermal reactivation of cholinesterase activity was used to correctly predict carbamates in 22 incidents and organophosphates in 59 incidents. Agreement (P < 0.001) between predictions based on cholinesterase activities and GC/MS results was significant.

Animals↗
PubMed1995

Bothrigaster variolaris (Trematoda: Cyclocoelidae) infection in two Florida snail kites (Rostrhamus sociabilis plumbeus).

Two Florida snail kites (Rostrhamus sociabilis plumbeus, Say) collected in August and December 1993 from Osceola County (28 degrees 15'N, 81 degrees 17'W) and Glades County (26 degrees 45'N, 81 degrees 10'W), Florida (USA), respectively, were infected with Bothrigaster variolaris (Trematoda: Cyclocoelidae); this parasite has not been reported previously from birds in the United States. One bird, a fledgling female, harbored 270 specimens of B. variolaris; the helminths caused airsacculitis and bronchitis, possible contributing factors in the death of this bird. The other bird, a subadult female, was infected with 40 trematodes and had gross and microscopic lesions consistent with trauma as the cause of death.

Air Sacs↗
PubMed1994

Bicycle-related head injuries in South Carolina children: what can we do to prevent them?

This review article demonstrates the clear need for helmet usage in children everywhere. The lives that could be changed and the money that could be saved from needless injury and death is substantial. As physicians and community leaders, we must all do our part to ensure the safety of children. This must be done by joining or initiating a local community campaign. Physicians need to become part of this preventive effort, both with their patients and by example. Hopefully, by following the suggestions of other programs already implemented throughout the United States and working together with the community, we can substantially decrease the number of needles bicycle injuries suffered by South Carolina's children.

Adolescent↗
PubMed1990

Myocardial revascularization for the third time. Clinical characteristics and follow-up.

Twenty-five patients presenting for a third revascularization procedure were retrospectively reviewed at Loyola University Medical Center, Maywood, IL. This represents 0.5 percent of the total revascularization cases over a five-year period extending from 1985 through 1989. Perioperative mortality was none, and seven complications occurred in six patients. Internal mammary arteries were used for revascularization in 60 percent of this group. Follow-up reveals that only one patient has died secondary to an arrhythmia. All patients except one are symptomatically improved, and 18 patients remain angina free at a mean follow-up of 22.3 months. It is therefore concluded that patients are clinically improved with a third revascularization, and this procedure should be offered as an effective means of treatment.

Female↗
PubMed1987

Ethanol-induced alterations in human erythrocyte shape and surface properties: modulatory role of prostaglandin E1.

Exposure of human erythrocytes to ethanol (1 to 20% by vol) in Ca2+ and Mg2+-free phosphate-buffered saline, pH 7.4, transformed biconcave discs into spiculated echinocytes within 3 min at 25 degrees C. The effects of ethanol were concentration-and time-dependent, but reversible by washing in the incubation buffer system within 60 min of initial exposure to ethanol. After prolonged ethanol exposure (180 min), washing of cells resulted in the formation of stomatocytes (cup-forms). Ethanol-induced echinocytosis was also accompanied by a 30% enhancement in the agglutinability of erythrocytes by ligands with high affinity for negative surface charge (poly-L-lysine and wheat germ agglutinin, 20 microliters/ml) without any alterations in surface charge topography. Concomitant exposure of erythrocytes to prostaglandin E1 (100 nM) selectively prevented the enhancement of ligand-mediated agglutinability, but did not modify cell shape. These data indicate that certain erythrocyte surface properties may not be directly influenced by cell shape and suggest a unique modulatory action of prostaglandin E1 on shape-transformed cells.

Alprostadil↗
PubMed1986

Ultrastructure of tight junctions in prostaglandin-exposed rat stomach.

The effect of intragastric misoprostol, a synthetic prostaglandin E1 methyl ester analog, on the morphology of rat stomach was studied by transmission and scanning electron microscopy. Adult male Sprague-Dawley rats received misoprostol at dose levels ranging from 50 to 1000 micrograms/kg body weight and were sacrificed after 30 min. At all dose levels, normal organelle ultrastructure was maintained in epithelial cells on the surface, within gastric pits, and lining the gastric glands. Quantitative freeze-fracture electron microscopy was used to examine the influence of misoprostol on epithelial-cell tight junctions, major structural components of the mucosal barrier. The numbers of intramembrane fibrils and the depths of the tight-junction complexes did not differ significantly between controls and animals exposed to 1000 micrograms/kg misoprostol (P greater than 0.05). Therefore, alterations in gastric epithelial tight-junction ultrastructure do not appear to account for the cytoprotective effect of misoprostol.

Alprostadil↗
PubMed1984

Seroprevalence of canine parvovirus in wild coyotes from Texas, Utah, and Idaho (1972 to 1983).

The prevalence of serum antibodies against canine parvovirus-2 (CPV-2), as measured by a standard hemagglutination-inhibition test, was determined in serum samples collected from 1,184 coyotes (Canis latrans) in Texas, Utah, and Idaho from 1972 to 1983. No evidence of parvoviral infection was found before 1979, after which seroprevalence rapidly increased to greater than 70% at all sites by 1982. There were minor differences in prevalence between age groups and among sites, but no consistent differences between sexes. The onset of CPV-2 seroprevalence in free-ranging coyotes coincided remarkably with the recognition of the clinical disease and seroprevalence in domestic dogs in the United States.

Age Factors↗
PubMedDate not supplied

Cardiac failure in hemolytic uremic syndrome and rescue with extracorporeal life support.

Extrarenal involvement manifesting in the cardiovascular system is a rare but potentially fatal complication of hemolytic uremic syndrome (HUS). Current treatment is aimed at cardiovascular supportive measures while awaiting organ recovery. However, there are cases in which this recovery never occurs, and patients succumb secondary to heart failure. We report two cases of severe cardiac failure in children in the acute phase of HUS and the use of extracorporeal membrane oxygenation (ECMO) to support one patient to cardiac recovery. Clinicians should be aware of this potentially life-threatening cardiac involvement and should consider the use of ECMO for potentially salvageable children with HUS.

Child, Preschool↗
PubMedDate not supplied

Myocardial calcification caused by secondary hyperparathyroidism due to dietary deficiency of calcium and vitamin D.

A 6-year-old girl presented with respiratory distress. Chest radiographs exhibited calcifications in the mediastinum. Further imaging revealed extensive cardiac calcifications on computed tomography of the chest. The laboratory parameters were consistent with findings of secondary hyperparathyroidism. Detailed review of her dietary history revealed a prolonged history of dietary deficiency of calcium and vitamin D. Treatment consisted of adequate daily replacement of calcium and ergocalciferol. On follow-up, her parathyroid hormone level was significantly reduced and substantially reduced cardiac calcifications were seen on echocardiogram. Pediatric cardiologists must be aware of this potentially fatal but treatable disease in children with cardiac calcifications unexplained by other causes.

Calcinosis↗