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Biomedical subjects

R Lee

Publications and source records attributed to R Lee.

At least 253 records · Page 14Linked to original sources
PubMed1991

Acute airway management in the critically ill child requiring transport.

Airway compromise was found to be a common problem in children requiring critical care transport to our hospital. This retrospective review of 39 infants and children was undertaken to assess the frequency and degree of airway compromise in these children, to document the management required and to determine who performed it. Ninety-seven per cent of children had airway difficulties associated with their disease, and one-third of these required further airway management on the arrival of the transport team. Airway specialists had not been involved in the care of these children before the arrival of the transport team. This indicates that greater attention should be paid to airway management as soon as children are identified as being sufficiently ill to require transport to a tertiary care facility.

Anesthesiology↗
PubMed1991

Mediastinal ependymoma.

A mediastinal ependymoma in a 35-year-old Caucasian woman is reported. The tumor was located in a paravertebral posterior mediastinal location. No continuity with the spinal canal or with the lung was identified. The diagnosis was confirmed by immunoperoxidase staining for glial fibrillary protein and by the presence of cilia within intracytoplasmic vacuoles. To the best of our knowledge, this is the second reported case of ependymoma in this location.

Adult↗
PubMed1991

Cerebral blood flow, cross-brain oxygen extraction, and fontanelle pressure after hypoxic-ischemic injury in newborn infants.

The relationship between mean arterial pressure, intracranial pressure, cerebral blood flow, cross-brain oxygen extraction, cerebral metabolic rate, and outcome was studied during therapy in nine neonates on 3 consecutive days after severe hypoxic-ischemic cerebral injury. Cross-brain oxygen extraction was significantly higher (5.06 +/- 0.5 vs 2.05 +/- 0.8 ml/dl; p = 0.012) in the five neonates who survived with normal neurologic outcome than in the four who died or sustained severe brain damage. In contrast, global cerebral blood flow in the five neonates with normal neurologic outcome was significantly lower (25.6 +/- 8.2 vs 83.2 +/- 44.9 ml/100 gm brain/min; p less than 0.05) during the study period. The differences in cross-brain oxygen extraction and global cerebral blood flow between infants who had neurologic recovery and those who died or sustained brain damage occurred in the presence of acceptable values for intracranial pressure, mean arterial pressure, and cerebral perfusion pressure. Our preliminary data suggest that cross-brain oxygen extraction and possibly global cerebral blood flow may be important variables associated with severe neuronal injury and death after hypoxic-ischemic cerebral injury.

Asphyxia Neonatorum↗
PubMed1991

The effects of acute moderate exercise on serum lipids and lipoproteins in mildly obese women.

The extent and duration of serum lipid and lipoprotein changes were examined in 12 mildly obese women who walked 45 minutes at 60% VO2max in a laboratory setting. A two-factor, 2 x 6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest) and the second factor was time (six times of measurement over a 24-hour period) with treatment counterbalanced. The patterns of change in total high-density lipoprotein-cholesterol (HDL-C) [F(5,55) = 5.75, p less than 0.001] and HDL3-C [F(5,55) = 2.62, p = 0.034], but not HDL2-C [F(5,55) = 1.15, p = 0.346], were significantly different between conditions. Relative to baseline and the rest condition, total HDL-C tended to rise due to a significant 11.6% increase in HDL3-C immediately post-exercise, with values returning to baseline 1.5 hours post-exercise. The interaction statistic for triglycerides was significant with trends for a decrease in triglycerides at 1.5 and 23 hours post-exercise relative to baseline and the rest condition. No significant differences were seen between the exercise and rest conditions for total cholesterol, low-density lipoprotein cholesterol, glucose, or plasma volume. These data indicate that an exercise intensity achievable by brisk walking (7.4 kph) is sufficient to evoke significant but short-term changes in serum HDL3-C concentrations in women.

Adult↗
PubMed1991

Investigating whether education of residents in a group practice increases the length of the outpatient visit.

This prospective study, carried out over an eight-week period in 1990, compared the amount of time required for 468 outpatients in an academic group practice (pediatric orthopedics) to be evaluated by an attending surgeon working with a resident with the time required for 216 patients in the same practice to be evaluated by the attending surgeon only. On the average, 24.2 minutes were added when a resident was involved: 12.6 of these for the resident's examination of the patient and the remaining 11.6 for the resident's discussion of the case with the attending surgeon. These findings suggest that the education process builds in a time cost not only for the patient but for the attending surgeon, who has less time to see additional outpatients than does a private practitioner or a physician in a health maintenance organization.

Academic Medical Centers↗
PubMed1991

Ankle mortise stability in Weber C fractures: indications for syndesmotic fixation.

A Weber type C ankle fracture was sequentially reproduced in 12 cadaver lower extremities and an external rotation torque was applied at each interval. The fractures were then repaired in staged fashion and the rotational stability of the mortise evaluated. Maximum external rotation of the talus within the mortise averaged 7.7 degrees in the intact ankle and increased by 311% to 31.8 degrees after creation of a Weber C injury. Rigid fixation of the fibular fracture restored 32% of the rotational stability, whereas isolated fixation of the medial malleolus reconstituted 57%. Fibular fixation combined with a syndesmotic screw restored 51% of original stability, and the addition of medial malleolar fixation improved stability to 101%. Bimalleolar fixation without a syndesmotic screw yielded 73% of the original rotational stability. The results of this study suggest that when rigid medial and lateral osteosynthesis can be achieved, syndesmotic fixation may not be necessary.

Ankle Injuries↗
PubMed1991

Brachial plexus birth injury.

Brachial plexus birth injuries occur at a frequency of 1-2 per 1000 births. Many of these injuries spontaneously resolve. Should spontaneous recovery not occur within the first 4-6 months of life, the prognosis for attaining movement and function of the affected appendage is significantly impaired. The child demonstrates a lifelong disfiguring and functional handicap. With advances in technology, diagnosis and microsurgical techniques, surgical exploration of the brachial plexus has been revived. A multidisciplinary approach has provided dynamic results. At present only one institution in the United States utilizes this innovative protocol. This article addresses the collaborative perioperative nursing implications for a child with brachial plexus birth injury.

Birth Injuries↗
PubMed1991

Plasma volume expansion in humans after a single intense exercise protocol.

We used intense intermittent exercise to produce a 10% expansion of plasma volume (PV) within 24 h and tested the hypothesis that PV expansion is associated with an increase in plasma albumin content. The protocol consisted of eight 4-min bouts of exercise at 85% maximal O2 uptake with 5-min recovery periods between bouts. PV, plasma concentrations of albumin and total protein (TP), and plasma osmolality were measured before and during exercise and at 1, 2, and 24 h of recovery from exercise. During exercise, PV decreased by 15%, while plasma TP and albumin content remained at control levels. At 1 h of recovery, plasma albumin content was elevated by 0.17 +/- 0.04 g/kg body wt, accounting for the entire increase in plasma TP content. PV returned to control level at 1 h of recovery without fluid intake by the subjects, despite a 820 +/- 120-g reduction in body weight. At 2 h of recovery, plasma TP content remained significantly elevated, and plasma TP and albumin concentration were significantly elevated. At 24 h of recovery, PV was expanded by 4.5 +/- 0.7 ml/kg body wt (10 +/- 1%), estimated from hematocrit and hemoglobin changes, and by 3.8 +/- 1.3 ml/kg body wt (8 +/- 3%), measured by Evans blue dye dilution. Plasma albumin content was increased by 0.19 +/- 0.05 g/kg body wt at 24 h of recovery. If 1 g of albumin holds 18 ml of water, this increase in plasma albumin content can account for a 3.4-ml/kg body wt expansion of the PV. No significant changes in plasma osmolality occurred during recovery, but total plasma osmotic content increased in proportion to PV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Effects of ginsenoside Rb1 on central cholinergic metabolism.

Ginsenosides, the saponins of ginseng, are bioactive ingredients which exert many beneficial effects. One ginsenoside, Rb1, extracted from North American ginseng (Panax quinquefolium L.), partially prevents the memory deficits induced by a cholinergic agent (scopolamine) in rats. In vitro studies show that Rb1 has no effect on quinuclidinyl benzylate binding or on acetylcholinesterase activity, but facilitates the release of acetylcholine (ACh) from hippocampal slices. The increase in ACh release is associated with an increased uptake of choline into nerve endings; however, calcium influx is unaltered. The ability of Rb1 to prevent memory deficits may be related to facilitation of ACh metabolism in the central nervous system.

Acetylcholine↗
PubMed1991

Variability of the respiratory gas exchange ratio during arterial puncture.

The value of R, the respiratory gas exchange ratio, was determined in 70 unselected outpatients while undergoing arterial blood sampling as part of routine pulmonary function testing. We wished to determine whether acute changes in alveolar ventilation occurring during blood drawing were of sufficient magnitude to cause a significant error in the calculation of alveolar PO2 if the value of 0.80 for R was assumed. In the majority of subjects, R ranged from 0.70 to 0.90. In approximately 25% of the cases, the assumption of the value of 0.80 for R would have led to an error equal to or greater than 10 mm Hg in the estimation of the alveolar-arterial PO2 difference.

Adult↗
PubMed1990

Differential degradation rates of the G protein alpha o in cultured cardiac and pituitary cells.

Signal transduction in biological membranes is modulated by a family of GTP-binding proteins termed G proteins. Differences in the tissue-specific expression of G protein subtypes suggest that the levels of individual G proteins may be an important determinant of the hormonal response in a given cell type. We have used a polyclonal antibody raised against the purified G protein, alpha o to study alpha o in the rat pituitary cell line GH4 and in primary rat cardiocytes in culture by quantitative immunoprecipitation. Biosynthetic labeling and specific immunoprecipitation of alpha o in pulse-chase experiments demonstrated that the t1/2 for alpha o degradation is 28 +/- 7 h (n = 4) in GH4 pituitary cells and is greater than 72 h (n = 4) in cardiocytes. The steady-state level of alpha o protein is similar in both cell types as measured by Western blots. Northern blots of poly(A)-selected mRNA from these two cell types were probed with labeled alpha o cDNA and showed they have similar alpha o mRNA levels. The observation of different degradation rates, but similar steady-state protein levels, suggests that the rate of alpha o synthesis is different in GH4 cells and cardiocytes. Since mRNA levels are approximately equal in both, our studies imply that protein translation controls may be important determinants of G protein alpha subunit concentrations in biological membranes.

Animals↗
PubMed1990

In vivo cytokine gene expression in T cell subsets of the autoimmune MRL/Mp-lpr/lpr mouse.

Expression of cytokine genes in freshly isolated T cell subsets in the autoimmune lpr mouse has been studied to determine what factors may be produced by these cells in vivo. RNA prepared from T cell subsets from diseased lpr mice and from the normal congenic strain, MRL/n, was tested for the presence of cytokine-specific message using the polymerase chain reaction. Cells of the expanded abnormal T cell subset were shown to express genes encoding interferon (IFN)-gamma, tumor necrosis factor (TNF)-beta, TNF-alpha and interleukin (IL)6, cytokines which are associated with inflammatory immune responses. These cells may thus play an important role in exacerbation of the pathological symptoms of the systemic autoimmune disease. These cells expressed no detectable IL1, IL2, IL3, IL4 or IL5. Phenotypically normal CD4+ and CD8+ T cells from both lpr and MRL/n also contained transcripts for IFN-gamma, TNF-alpha, TNF-beta and IL6. IL2 mRNA was found almost exclusively in the CD4+ subset, indicating that the CD8+ T cells in the lpr mouse are not highly activated through their class I major histocompatibility complex molecules to produce IL2, as could occur if a virus infection was inducing autoimmunity in these mice. Similar levels of IL2 mRNA were present in the CD4+ T cells of lpr and MRL/n mice, demonstrating that these cells are not defective in IL2 production in vivo.

Animals↗
PubMed1990

A monoclonal mouse anti-human IL-2 receptor antibody (anti-Tac) will recognize molecules on the surface of Xenopus laevis immunocytes which specifically bind rIL-2 and are only slightly larger than the human Tac protein.

We have made visible the binding of a mouse monoclonal anti-human interleukin 2 (IL-2) receptor (anti-Tac) antibody on the surface of phytohemagglutinin (PHA)-stimulated Xenopus thymocytes using a colloidal gold-conjugated goat anti-mouse antibody and transmission electron microscopy. No binding was found when a different mouse monoclonal antibody (mAb) of the same isotype and subclass was tested, or when the anti-Tac antibody was omitted from the procedure. After metabolic radiolabeling of the IL-2 receptors with [35S]methionine using PHA-stimulated thymocytes of Xenopus laevis, the South African clawed toad, we show that a concentrated preparation of the mouse anti-human Tac antibody will immunoprecipitate a radiolabeled molecule just slightly larger than 55 kDa. Phorbol dibutyrate (PDB), an effective T cell mitogen, and cyclosporin A, an inhibitor of T cell mitogenesis in this species, are both capable of regulating the expression of this IL-2-binding molecule on Xenopus immunocytes. Here, we use the calcium ionophore A23187 to show that the relationship between IL-2 receptor expression and mitogenesis, which was previously established in X. laevis, is associated with a calcium ion flux. Flow cytometry is used for assaying alterations in epitope expression after binding the lectin-stimulated cells under test with a fluorescence (Fl*) conjugate of the anti-Tac antibody or a control mAb, which is either anti-DNP or anti-keyhole limpet hemocyanin (KLH) in specificity, but of the same mouse isotype and subclass as the anti-IL-2 receptor antibody.

Animals↗
PubMed1990

Rat monoclonal antibody distribution in mice: an epitope inside the lung vascular space mediates very efficient localization.

MoAb to an epitope on lung endothelial cells accumulates rapidly in the lung resulting in localization ratios of over 100. MoAb to a macrophage antigen found in spleen and lung has maximum localization ratios of 24 and 5, respectively, while MoAb specific for a human tumor grown in nude mice has a maximum ratio of about 4. Epitope concentrations in target organs (300-600 ng/mg protein) are comparable in all three systems, indicating that the MoAb to endothelium is efficient in localization to the lung.

Adenocarcinoma, Bronchiolo-Alveolar↗