Search PubMed⌕ Search

Biomedical subjects

R L Scott

Publications and source records attributed to R L Scott.

At least 55 records · Page 3Linked to original sources
PubMed1985

Plasma fibronectin metabolism during hemorrhagic shock and starvation.

In this report we characterize the response of the plasma protein fibronectin to hemorrhagic shock and starvation, conditions associated with decreased function of mononuclear phagocyte system (MPS). Rats were starved for 3 days, then half of the animals were subjected to fixed-volume hemorrhagic shock by removing an estimated 35% of their blood volumes for 20 min. After volume replacement, animals were injected iv with [14C]valine. At time points up to 10 hr after hemorrhage, plasma fibronectin concentrations and fibronectin synthesis were quantitated. In additional rats treated identically, fibronectin clearance was assessed by measuring the disappearance of 125I-fibronectin from the plasma. When compared to control animals, either starvation or hemorrhagic shock produced similar perturbations in plasma fibronectin metabolism; fibronectin concentrations were reduced from 241.3 +/- 34.6 micrograms/ml (mean +/- SEM) (controls) to 123 +/- 32.6 micrograms/ml (starvation) or 150.0 +/- 13.0 micrograms/ml (hemorrhage). Plasma [14C]fibronectin specific radioactivities, indicative of fibronectin synthesis, were also significantly reduced. Hemorrhagic shock in rats that previously had been starved did not depress fibronectin concentrations or synthesis to a greater extent than starvation alone. The rates of 125I-fibronectin clearance were increased in starvation and hemorrhagic shock (t1/2 = 233.0 +/- 13.0 min, controls; 174.6 +/- 10.7 min, starvation; 167.4 +/- 13.6 min, hemorrhage). In contrast to changes observed in fibronectin metabolism, total plasma protein concentrations were not significantly altered in any experimental groups. Furthermore, total plasma protein synthesis increased in rats subjected to either starvation or hemorrhagic shock, but decreased in starved rats that were subsequently shocked.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Isolated left thoracic isomerism.

Left thoracic isomerism may present as an isolated anomaly without symptoms. The chest radiograph demonstrates characteristic right hilar findings that may be misinterpreted as a hilar mass. Computed tomography of the chest is recommended to confirm the correct diagnosis.

Humans↗
PubMed1985

The inquiry approach in dental hygiene education.

A study was done to assess the impact of an inquiry-oriented curriculum in a dental hygiene program. Two instruments, designed to measure student perception of personal and faculty inquiry and disinquiry behavior, were administered to four consecutive classes twice a year between 1978 and 1981. Junior and senior students perceived a significant increase in faculty inquiry behavior and, initially, a decrease in disinquiry behavior. Time in the program affected student disinquiry behavior at a significant level, though no significant change was seen in inquiry behavior. National Board mean scores improved, and several categories of clinical productivity increased significantly during this period. The implications of these findings are discussed.

Curriculum↗
PubMed1983

Dog lymph flow in increased capillary permeability states.

The lung lymph flow rate (QL) is increased in edema caused by an increase in lung microvascular permeability. This increase in QL could be caused by either a decrease in the effective resistance of the lymph vessels (RL), or by an increase in the effective lymph driving pressure (PL), or by a change in both RL and PL. We estimated PL and RL from the linear relationship between QL and the pressure at the outflow end (PO) of five cannulated dog lung lymph vessels (RL = - delta Po/delta QL and PL = the PO at which QL = 0). We increased lung microvascular permeability by giving the dogs 100 mg/kg of alloxan and found that QL increased from 24.5 +/- 8.9 microliters/min to 112 +/- 41 microliters/min (mean +/- SD). RL decreased from 0.35 +/- 0.12 to 0.11 +/- 0.04 cm H2O min/microliters and PL increased from 8.5 +/- 1.5 to 15.9 +/- 2.7 cm H2O. We then increased the capillary pressures from 18.3 +/- 3.8 to 41.3 +/- 7.3 cm H2O and QL increased to 169.9 +/- 47.8 microliters/min. PL increased by an additional 6.3 cm H2O but RL decreased by only an additional 0.02 cm H2O min/microliters. These results show that the QL vs PO relationship is changed in edema secondary to an increase in microvascular permeability, and that this change can be represented as changes in RL and PL. In terms of these parameters, QL increased in edema as a result of a decrease in RL and an increase in PL.

Alloxan↗
PubMed1983

Effect of Escherichia coli endotoxin on dog lung fluid balance.

Endotoxin may cause an increase in pulmonary capillary permeability and thus promote edema formation. We used a gravimetric technique to estimate the pulmonary capillary filtration coefficient (KF) and the maximum capillary pressure at which the lung could maintain a constant weight (Pccritical) in dogs after intravenous administration of Escherichia coli (E. coli) endotoxin. KF should be increased and Pccritical should be decreased by an increase in permeability. Four groups of three to four dogs were given 1, 10, 1,000, or 3,000 micrograms/kg of endotoxin. A fifth group of five dogs, which served as controls, was given no endotoxin. KF was significantly (P less than 0.05) greater than control [0.049 +/- 0.031 (SD) ml . min-1 . mmHg-1] in only the 1-micrograms/kg group (0.100 +/- 0.027), indicating a possible increase in permeability. However, changes in capillary surface area may have affected KF. Pccritical was not significantly different from control (20.7 +/- 2.4 mmHg) in any of the E. coli groups. We conclude from these results that E. coli endotoxin may have caused a slight increase in permeability; however, the lung retained its ability to resist edema formation.

Animals↗
PubMed1983

Relationship between weight gain and lymph flow in dog lungs.

Lung weight is a useful indicator of increases in lung extravascular volume. In addition, the lung lymph flow rate (QL) is an important factor in lung fluid balance. We have studied the weight and QL responses to elevations in capillary pressure (Pc) in intact dog lung lower left lobes. We measured lobe weight continuously. We also measured QL from small lymph vessels from the same lobes. The base-line QL was 1.7 +/- 1.5 microliter/min, and the weight was constant. After we increased Pc by 8-20 cmH2O, both weight and QL increased transiently. In most lungs the weight reached a new steady state. When we increased Pc further, weight increased continuously; however, QL reached a plateau. The continuous weight gain was due to edema. These results show that weight and QL respond similarly in nonedematous lungs; however, the weight and QL responses in edematous lungs may be different.

Animals↗
PubMed1983

Pulmonary microvascular permeability after coronary arterial ligation in dogs.

Recent studies have indicated that pulmonary microvascular permeability may be increased after coronary arterial ligation. We tested this by estimating the pulmonary microvascular reflection coefficient (delta) in six anesthetized control dogs and in six dogs in which we ligated the left anterior descending coronary artery. We cannulated lung lymph vessels and measured the lymph and plasma protein concentrations (CL and CP, respectively). The left atrial pressure was increased to decrease CL to a minimum. We used the minimum CL to estimate delta as 1 -CL/CP. delta for the control [0.70 +/- 0.03 (SD)] and coronary artery ligated groups (0.70 +/- 0.04) were almost identical. This data indicates that coronary artery ligation does not increase pulmonary microvascular permeability.

Animals↗
PubMed1983

Avoidance of negative percutaneous lung biopsy using contrast-enhanced CT.

Fluoroscopically guided percutaneous biopsy of pulmonary masses is an accepted procedure, but large neoplasms often have necrotic areas which, if aspirated, do not afford a pathologic diagnosis. Such tumors may require multiple punctures or procedures to establish a diagnosis. A prebiopsy contrast-enhanced CT scan selectively demonstrates the extent of peripherally located, viable tumor tissue. Three cases of initially frustrated lung biopsies in which viable, diagnostic tissue was localized for fluoroscopic aspiration using the contrast-enhanced CT scan are presented.

Biopsy, Needle↗
PubMed1983

The supine view in double-contrast knee arthrography.

Knee arthrography is a widely used diagnostic procedure, but there is disagreement regarding the relative efficacy of single vs. double-contrast examinations in the evaluation for meniscal tears. In 353 double-contrast knee arthrograms, combining supine positioning with the routinely accepted prone views, there were 222 meniscal tears diagnosed using prone positioning alone, and seven additional tears were found with the added supine maneuver. Even though the knee joint was distended with both contrast material and air, the prone views tended to outline the meniscus in a double-contrast fashion, whereas the supine views provided single positive contrast detail of the same area. Supine views are particularly helpful when an obvious meniscal tear is not fluoroscopically apparent during prone filming.

Adolescent↗
PubMed1983

Fluid-level motion artifact in computed tomography.

Ingestion of oral contrast material as a routine part of abdominal computerized tomographic scanning creates numerous gas and fluid interfaces within the gastrointestinal tract. Following deep inspiration or expiration, fluid motion induced by shifting intra-abdominal contents persists for several seconds. This causes radial streak artifacts to arise from air-fluid interfaces, even though respiration is suspended while the scan is made. Such artifacts can be reduced if the beginning of a scan is delayed to allow fluid motion to stop. An alternative is to re-scan an area of interest in the lateral decubitus position so as to shift air-fluid levels and their associated artifacts away from any region in question.

Contrast Media↗
PubMed1982

Comparative effects of phosphoenolpyruvate on selected mammalian erythrocytes.

1. Incubation of human, rat, cow, sheep, dog, rabbit and monkey erythrocytes with phosphoenolpyruvate (PEP) resulted in increased intracellular 2,3-diphosphoglycerate (2,3-DPG). 2. Physiologic temperature (37 degrees C) and a pH less than 6.5 were required for transport and metabolism of PEP in rat and monkey erythrocytes. 3. Although erythrocytes from all species (except pig) exhibited PEP transport and metabolism, hemoglobin oxygen affinity (HOA) was affected only in species whose hemoglobins are sensitive to 2,3-DPG. 4. These results suggest that the effect of PEP incubation on HOA is mediated through 2,3-DPG.

2,3-Diphosphoglycerate↗
PubMed1982

Perfused rat hindlimb wound model: lambda-carrageenan induced.

We established an isolated perfused rat hindlimb wound model using intramuscular injections of lambda-carrageenan. Wound and control hindlimbs of 24-h fasting anesthetized (phenobarbital sodium, 5 mg/100 g body wt) rats were perfused for 60 min (10 ml/min) with media containing 10 mM glucose and physiological levels of amino acids. Analysis of perfusate showed a significant increase in glucose clearance and lactate production from the wounded hindlimb but no significant difference in tissue adenine nucleotide levels. Alterations in net amino acid release were measured over a 60-min period; all amino acids were released in greater concentration from wounded hindlimbs. Comparison of amino acid release, normalized for phenylalanine concentration, suggested the following alterations in amino acid metabolism by the wounded tissue: depressed threonine, glycine serine and alanine release, and increased release of the branched chain amino acids (BCAA), leucine, isoleucine, and valine. The increased release and intracellular concentration of BCAA was supported by decreased BCAA transaminase activity in the wounded muscle tissue. This result may explain the decreased alanine release from the wounded hindlimbs.

Adenine Nucleotides↗