Search PubMed⌕ Search

Biomedical subjects

K A Davis

Publications and source records attributed to K A Davis.

At least 37 records · Page 2Linked to original sources
PubMed1999

Granulocyte colony-stimulating factor and neutrophil-related changes in local host defense during recovery from shock and intra-abdominal sepsis.

BACKGROUND: We have reported that treatment with exogenous granulocyte colony-stimulating factor (G-CSF) improves abscess localization and reduces mortality without aggravating neutrophil (PMN)-mediated reperfusion injury in a model of septic abdominal trauma. The purpose of this study was to determine actions of G-CSF on PMN function in the peritoneum. METHODS: Anesthetized swine were pretreated with broad-spectrum antibiotics and underwent cecal ligation and incision and 35% hemorrhage (trauma). After 1 hour they were resuscitated with shed blood, crystalloid, and either G-CSF (n = 10) or saline solution vehicle (n = 9). The animals were observed for 72 hours. RESULTS: After trauma, saline solution treatment increased PMN infiltration into the peritoneum within 2 hours (P = .035), increased peritoneal PMN elastase production (i.e., cytotoxicity) by 24 hours (P = .004), and decreased adherence of peritoneal PMNs to an artificial substrate from 4 to 72 hrs (P = .043). The mean autopsy score was 7.0 +/- 0.5. With G-CSF treatment peritoneal neutrophilia was enhanced (maximum 48 hours, P = .002) and PMN cytotoxicity was augmented and delayed (maximum 48 hours, P = .004). Despite these changes, adherence of peritoneal PMNs was not significantly changed and there was no evidence for PMN-mediated damage in the lung as judged by bronchoalveolar lavage protein, bronchoalveolar lavage PMNs, lung tissue myeloperoxidase, or histologic changes. The mean autopsy score was improved to 4.1 +/- 0.3 (P < .001). CONCLUSIONS: G-CSF in resuscitation fluids improved localization of an intra-abdominal septic focus by increased production of circulating PMNs, increased PMN extravasation into the peritoneal cavity, and increased PMN cytotoxicity at the abdominal septic focus, without exaggerating PMN-dependent reperfusion injury in the lung. Therefore these data further support the idea that G-CSF in resuscitation fluids might reduce septic complications in the multiply injured trauma patient.

Animals↗
PubMed1998

Normal human CD4+ memory T cells display broad heterogeneity in their activation threshold for cytokine synthesis.

CD4+ memory T cells coordinate immune responses against viruses and other pathogens via the Ag-induced secretion of potent effector cytokines. The efficacy of these responses depends on both the overall number of pathogen-specific memory T cells and the particular array of cytokines that these cells are programmed to secrete. Here, we provide evidence that heterogeneity in Ag triggering thresholds constitutes an additional critical determinant of memory T cell function. Using a novel assay that allows single-cell detection of Ag-specific T cell cytokine production, we demonstrate that CMV-specific CD4+ memory cells from human peripheral blood display pronounced differences in their costimulatory requirements for Ag-induced triggering of IFN-gamma and IL-2 secretion, ranging from cells that trigger with little costimulation (e.g., resting APC alone) to cells requiring potent costimulation through multiple pathways (resting APC plus multiple costimulatory mAbs, or activated APC). These differences in costimulatory requirements are independent of clonal differences in TCR signaling intensity, consistent with an intrinsic activation-threshold heterogeneity that is "downstream" from the TCR. Thus, "effective" frequencies of Ag-specific CD4+ memory T cells appear to depend on the activation status of available APC, a dependence that would allow the immune system to rapidly adjust the number of functional Ag-specific memory T cells in a particular effector site according to local conditions.

Antibodies, Monoclonal↗
PubMed1998

Determination of CD4 antigen density on cells: role of antibody valency, avidity, clones, and conjugation.

The number of R-phycoerythrin (R-PE)-conjugated antibodies bound to a cell can be quantitated on a flow cytometer by using beads with known numbers of attached R-PE molecules (QuantiBRITE PE). Using these reference beads, we have observed that a number of factors affect the accuracy of the quantitation and conclusions about epitope density. These factors include valence of antibody binding, the use of antibody fragments (Fab's) versus intact monoclonal antibodies (mAb's), fixation, the purity of the conjugate (i.e., percentage of 1:1 ratios), dissociation rate, the use of washed versus unwashed preparations, and the location of epitope on target antigen. We used CD4 on T cells as a model to explore these challenges in detail. We conclude that CD4+ T cells bind approximately 49,000 CD4 (Leu 3a) antibody molecules, that this binding is bivalent, and therefore that there are approximately 98,000 CD4 antigen molecules on the surface of these cells.

Antibodies, Monoclonal↗
PubMed1998

Quantitation of CD38 expression using QuantiBRITE beads.

The QuantiBRITE bead method was compared with the CD4 biological calibration method for quantitation of CD38 expression on CD8+ T-lymphocytes of Multicenter AIDS Cohort Study participants. Results were expressed as CD38 antibodies bound per cell (ABCs) and were the same with the two methods provided two conditions were met. These were the use of repurified (> 95% of the monoclonal antibodies [mAbs] have 1 phycoerythrin [PE] molecule per mAb) CD38-PE for both methods and use of repurified CD4-PE to calculate the relative fluorescence intensity multiplier for the CD4 biological calibration method. Our results indicate that the prognostic significance of CD38 values obtained using the QuantiBRITE method can be interpreted using previously published reports (Liu et al.: J Acquir Immune Defic Syndr Hum Retrovirol 16:83-92, 1997 and 18:332-340, 1998). Sample preparation using NH4Cl and FACS lysing solution gave similar results for CD38 relative fluorescence intensity. Dilution into either phosphate-buffered saline with 2% fetal calf serum and 0.1% sodium azide or fixation in 1% paraformaldehyde for 1 or 24 h also gave similar results. In experiments using Raji cells, which express high levels of CD38, the valence of binding of the intact Leu 17 antibody was approximately 68% bivalent and approximately 32% monovalent. This emphasizes the complexity of determining antigen density from ABCs. We conclude that repurified PE conjugates of CD38, which can be consistently made, together with QuantiBRITE PE beads, provide a convenient and reliable method for quantitation of CD38 expression as ABCs.

ADP-ribosyl Cyclase↗
PubMed1998

Staining of cell surface human CD4 with 2'-F-pyrimidine-containing RNA aptamers for flow cytometry.

We have used recombinant human CD4 presented on beads as an affinity matrix to screen a 2'-F-pyrimidine-containing RNA library with a complexity of approximately 10(14) molecules. Affinity-selected aptamers bind recombinant CD4 with low nanomolar equilibrium dissociation constants. These high-affinity aptamers conjugated to different fluorophores such as fluorescein and phycoerythrin were used to stain cells, expressing human CD4 on cell surface, for analysis by flow cytometry. Aptamers, conjugated to fluorophores, stained mouse T cells that express human CD4 on the surface, but not the control mouse T cells lacking human CD4. The control cells, however, do express mouse CD4 whose extracellular domain has 55% sequence identity to the human form. These human CD4-specific aptamers selectively stained CD4(+) T cells in a preparation of human peripheral blood mononuclear cells. These results and others suggest that aptamers are emerging as a versatile class of molecules that can be used for various diagnostic applications performed under different formats or platforms.

Amino Acid Sequence↗
PubMed1998

Acetylcholine metabolism in the inflamed rat intestine.

Acetylcholine (ACh) is a major neurotransmitter in the enteric nervous system. Since increasing evidence suggests that inflammation alters neural regulation of intestinal function, we examined the synthesis and breakdown of ACh in smooth muscle/myenteric plexus (SM/MP) preparations from the jejunum of the rat during inflammation caused by infection with the nematode parasite Trichinella spiralis. Both total and neuron-specific uptake of the ACh precursor [3H]choline into SM/MP preparations was increased by over twofold on Day 6 postinfection. Further, a radiochemical assay of choline acetyltransferase activity showed significant increase by Day 1, with peak values reached by Day 3 and maintained without reversal thereafter. Despite the enhancement of these steps, measurement of the conversion of [3H]choline into [3H]ACh in SM/MP preparations in vitro showed a nearly fourfold decrease by Day 6, implying a large decrease in ACh production in the inflamed jejunum. Examination of acetylcholinesterase in the rat jejunum showed decreased histochemical staining intensity in the muscle wall, and quantitative evaluation showed significantly decreased (>50%) acetylcholinesterase activity in SM/MP preparations. These results show that cholinergic innervation of the intestine can undergo rapid and long-lasting alterations during inflammation. Upregulation of major steps in the synthetic pathway for ACh was not matched by increased ACh production, suggesting that defects in ACh packaging, storage, and granule exocytosis may also be present.

Acetylcholine↗
PubMed1998

Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture.

OBJECTIVE: There were two aims of this study. The first was to evaluate the application of helical computed tomography of the thorax (HCTT) for the diagnosis of blunt aortic injury (BAI). The second was to evaluate the efficacy of beta-blockers with or without nitroprusside in preventing aortic rupture. SUMMARY BACKGROUND DATA: Aortography has been the standard for diagnosing BAI for the past 4 decades. Conventional chest CT has not proven to be of significant value. Helical CT scanning is faster and has higher resolution than conventional CT. Retrospective studies have suggested the efficacy of antihypertensives in preventing aortic rupture. METHODS: A prospective study comparing HCTT to aortography in the diagnosis of BAI was performed. A protocol of beta-blockers with or without nitroprusside was also examined for efficacy in preventing rupture before aortic repair and in allowing delayed repair in patients with significant associated injuries. RESULTS: Over a period of 4 years, 494 patients were studied. BAI was diagnosed in 71 patients. Sensitivity was 100% for HCTT versus 92% for aortography. Specificity was 83% for HCTT versus 99% for aortography. Accuracy was 86% for HCTT versus 97% for aortography. Positive predictive value was 50% for HCTT versus 97% for aortography. Negative predictive value was 100% for HCTT versus 97% for aortography. No patient had spontaneous rupture in this study. CONCLUSIONS: HCTT is sensitive for diagnosing intimal injuries and pseudoaneurysms. Patients without direct HCTT evidence of BAI require no further evaluation. Aortography can be reserved for indeterminate HCTT scans. Early diagnosis with HCTT and presumptive treatment with the antihypertensive regimen eliminated in-hospital aortic rupture.

Adrenergic beta-Antagonists↗
PubMed1998

Improved success in nonoperative management of blunt splenic injuries: embolization of splenic artery pseudoaneurysms.

OBJECTIVES: By using abdominal computed tomographic scans in the evaluation of blunt splenic trauma, we previously identified the presence of vascular blush as a predictor of failure, with a failure of nonoperative management of 13% in that series. This finding led to an alteration in our management scheme, which now includes the aggressive identification and embolization of splenic artery pseudoaneurysms. METHODS: The medical records of 524 consecutive patients with blunt splenic injury managed over a 4.5-year period were reviewed for the following information: age, Injury Severity Score (ISS), American Association for the Surgery of Trauma splenic injury grade (SIG), method and outcome of management. RESULTS: Of the patients, 66% were male with a mean age of 32 +/- 16, and mean ISS of 25 +/- 13. A total of 180 patients (34%) were managed with urgent operation on admission (81% splenectomy (SIG 4.0), 19% splenorrhaphy (SIG 2.6)). The remaining 344 patients (66%) were hemodynamically stable and underwent computed tomographic scan and planned nonoperative management. Of these patients, 322 patients (94%) were successfully managed nonoperatively (61% of total splenic injuries). In 26 patients (8%), a contrast blush identified on computed tomographic scan was confirmed as a parenchymal pseudoaneurysm on arteriography. Twenty patients (SIG, 2.8) were successfully embolized. In six patients, technical failure precluded embolization; all required splenectomy (SIG, 4.0). A total of 22 patients (6%) failed nonoperative management, including the six with unsuccessful embolization attempts. Sixteen patients (SIG, 3.0) who had no evidence of pseudoaneurysm were explored for a falling hematocrit, hemodynamic instability, or a worsening follow-up computed tomography: 13 patients had splenectomy, and three patients had splenorrhaphy. CONCLUSIONS: Aggressive surveillance for and embolization of posttraumatic splenic artery pseudoaneurysms improved the rate of successful nonoperative management of blunt splenic trauma to 61%, with a nonoperative failure rate of only 6%. In comparison with our previous work, this reduction in failure of nonoperative management is a significant improvement (p < 0.03).

Adolescent↗
PubMed1997

A flow cytometric immunoassay for beta2-microglobulin in whole blood.

Flow cytometers can discriminate a single particle type in an unwashed whole blood sample. Utilizing this capability. we devised a homogeneous bead-immobilized sandwich immunoassay for soluble beta2M (beta2-microglobulin) in whole blood, utilizing an antibody that discriminates soluble from cellular beta2M. A 4 microm bead was chosen that fluoresces only in a FACScan flow cytometer's FL3 channel. thus allowing triggering on this bead to the exclusion of the many blood cell events. The bead was adsorbed with a capture antibody (clone A7801) which binds only to soluble and not to cellular beta2M. This antibody appears to recognize an epitope on beta2M which interfaces to the heavy chain of cellular Class I MHC molecules. The signal antibody (PE conjugate of clone L376, emitting in the FL2 channel) binds to both soluble and cellular beta2M (present in roughly equal amounts in normal blood). The various parameters required for a flow cytometric immunoassay were optimized. The 4 microm sized bead was adequately large to give a near full scale signal at saturation. The relative amounts of signal antibody and capture beads were balanced to give a low blank, minimal 'hook effect', and reasonable event rate on the flow cytometer. The amount of blood added was selected to give a signal near the bottom of the immunassay range for normals with the higher range available for clinical samples. The assay requires no washing, minimizes blood handling, and has a working range (2.5 decades) that is compatible with the biological range of beta2M concentrations with a single blood dilution.

Animals↗
PubMed1997

P-glycoprotein function involves conformational transitions detectable by differential immunoreactivity.

The MDR1 P-glycoprotein (Pgp), a member of the ATP-binding cassette family of transporters, is a transmembrane ATPase efflux pump for various lipophilic compounds, including many anti-cancer drugs. mAb UIC2, reactive with the extracellular moiety of Pgp, inhibits Pgp-mediated efflux. UIC2 reactivity with Pgp was increased by the addition of several Pgp-transported compounds or ATP-depleting agents, and by mutational inactivation of both nucleotide-binding domains (NBDs) of Pgp. UIC2 binding to Pgp mutated in both NBDs was unaffected in the presence of Pgp transport substrates or in ATP-depleted cells, whereas the reactivities of the wild-type Pgp and Pgps mutated in a single NBD were increased by these treatments to the level of the double mutant. These results indicate the existence of different Pgp conformations associated with different stages of transport-associated ATP hydrolysis and suggest trapping in a transient conformation as a mechanism for antibody-mediated inhibition of Pgp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Granule cell activation of complex-spiking neurons in dorsal cochlear nucleus.

Dorsal cochlear nucleus (DCN) principal cells receive, in addition to their well known auditory inputs, various nonauditory inputs via a cerebellar-like granule cell circuit located in the superficial layers of the DCN. Activation of this circuit (granule cell axons make excitatory synapses on the principal cells but also contact inhibitory interneurons that project to the principal cells) produces strong inhibition of the principal cells. Here we investigate the role of cartwheel cells, homologs of cerebellar Purkinje cells, in producing this inhibition. The responses of type IV units (one type of principal cells) and of cartwheel cells were recorded to ortho- and antidromic activation of the granule cells (i. e., by stimulation of their inputs from the somatosensory cuneate and spinal trigeminal nuclei and by direct stimulation of their parallel fiber axons). Cartwheel cells were identified on the basis of recording depth and complex action potential shape. A four-pulse facilitation paradigm (four pulses at 50 msec intervals) was used; this stimulus allows separation of the apparently simple inhibitory somatosensory response of type IV units into a three-component (inhibition-excitation-inhibition) response. As expected, cartwheel cells are excited by granule cell activation; the latencies and four-pulse amplitudes of these responses correspond to the properties of the second, long-latency inhibitory component of type IV responses. The source of the first, short-latency inhibitory response is still unknown. Nevertheless, these results show that cartwheel cells convey inhibitory polysensory information to DCN principal cells.

Animals↗
PubMed1997

Affinity modulation of platelet integrin alphaIIbbeta3 by beta3-endonexin, a selective binding partner of the beta3 integrin cytoplasmic tail.

Platelet agonists increase the affinity state of integrin alphaIIbbeta3, a prerequisite for fibrinogen binding and platelet aggregation. This process may be triggered by a regulatory molecule(s) that binds to the integrin cytoplasmic tails, causing a structural change in the receptor. beta3-Endonexin is a novel 111-amino acid protein that binds selectively to the beta3 tail. Since beta3-endonexin is present in platelets, we asked whether it can affect alphaIIbbeta3 function. When beta3-endonexin was fused to green fluorescent protein (GFP) and transfected into CHO cells, it was found in both the cytoplasm and the nucleus and could be detected on Western blots of cell lysates. PAC1, a fibrinogen-mimetic mAb, was used to monitor alphaIIbbeta3 affinity state in transfected cells by flow cytometry. Cells transfected with GFP and alphaIIbbeta3 bound little or no PAC1. However, those transfected with GFP/beta3-endonexin and alphaIIbbeta3 bound PAC1 specifically in an energy-dependent fashion, and they underwent fibrinogen-dependent aggregation. GFP/beta3-endonexin did not affect levels of surface expression of alphaIIbbeta3 nor did it modulate the affinity of an alphaIIbbeta3 mutant that is defective in binding to beta3-endonexin. Affinity modulation of alphaIIbbeta3 by GFP/beta3-endonexin was inhibited by coexpression of either a monomeric beta3 cytoplasmic tail chimera or an activated form of H-Ras. These results demonstrate that beta3-endonexin can modulate the affinity state of alphaIIbbeta3 in a manner that is structurally specific and subject to metabolic regulation. By analogy, the adhesive function of platelets may be regulated by such protein-protein interactions at the level of the cytoplasmic tails of alphaIIbbeta3.

Animals↗
PubMed1997

Modeling inhibition of type II units in the dorsal cochlear nucleus.

Type II units in the dorsal cochlear nucleus (DCN) are characterized by vigorous but nonmonotonic responses to best frequency tones as a function of sound pressure level, and relatively weak responses to noise. A model of DCN neural circuitry was used to explore two hypothetical mechanisms by which neurons may be endowed with type II unit response properties. Both mechanisms assume that type II units receive excitatory input from auditory nerve (AN) fibers and inhibitory input from an unspecified class of cochlear nucleus interneurons that also receive excitatory AN input. The first mechanism, a lateral inhibition (LI) model, supposes that type II units receive inhibitory input from a number of narrowly tuned interneurons whose best frequencies (BFs) flank the BF of the type II unit. Tonal stimuli near BF result in only weak inhibitory input, but broadband stimuli recruit enough lateral inhibitors to greatly weaken the type II unit response. The second mechanism, a wideband inhibition (WBI) model, supposes that type II units receive inhibitory input from interneurons that are broadly tuned so that they respond more vigorously to broadband stimuli than to tones. Physiological and anatomical evidence points to the possible existence of such a class of neurons in the cochlear nucleus. The model extends an earlier computer model of an iso-frequency DCN patch to multiple frequency slices and adds a population of interneurons to provide the inhibition to model type II units (called 12-cells). The results show that both mechanisms accurately simulate responses of type II units to tones and noise. An experimental paradigm for distinguishing the two mechanisms is proposed.

Acoustic Stimulation↗
PubMed1997

Evidence of stimulus-dependent correlated activity in the dorsal cochlear nucleus of decerebrate gerbils.

Cross-correlation analysis of simultaneously recorded spike trains was used to study the internal organization of the dorsal cochlear nucleus (DCN) of unanesthetized decerebrate Mongolian gerbils. The goal was to test the model (adapted from cat) that its principal cells (type III and type IV units) receive three sources of shared auditory input: excitatory input from the auditory nerve; inhibitory input from DCN interneurons (vertical cells; type II and type II-i units) that respond vigorously to tones; and inhibitory input from ventral cochlear nucleus principal cells (D-stellate cells; wideband inhibitors) that conversely respond vigorously to noise. Records of spontaneous and/or driven activities (to long-duration tones and frozen broadband noise) were obtained for 51 pairs consisting of type II, type III, and type IV units; type III units inhibited by low-level noise were subclassified as type III-i units. Pairs were isolated with two electrodes to study the effect of differences in unit best frequencies (BFs) on correlation. All correlated pairs composed of type III and type IV units (17 of 31 pairs) showed central mounds (CMs), indicative of shared input, in their cross-correlograms. These data exhibited two important properties: pairs with similar BFs were more likely to show CMs, and the shape of the CMs was stimulus dependent. That is, CM width typically changed sharply from wide to narrow with increasing level; significantly, transition-level CMs were either a composite of these shapes or not present. The transition to only narrow CMs occurred above the thresholds of type II and type III-i units to tones, but below their thresholds to noise. Cross-correlograms derived from the tone-evoked activities of pairs involving type II units (3 of 6 pairs) showed inhibitory troughs (ITs); unexpectedly, type III-i units were involved in both IT and CM pairs, suggesting that this unit type may reflect recordings from both vertical and principal cells. Overall, the results are interpretable in terms of the model of gerbil DCN that was adapted from cat, suggesting that the model generalizes across species. Compared with cat, however, gerbil principal cell responses (predominantly type III unit properties) are less dominated by inhibition.

Acoustic Stimulation↗
PubMed1996

Differentiation and stability of T helper 1 and 2 cells derived from naive human neonatal CD4+ T cells, analyzed at the single-cell level.

The development of CD4+ T helper (Th) type 1 and 2 cells is essential for the eradication of pathogens, but can also be responsible for various pathological disorders. Therefore, modulation of Th cell differentiation may have clinical utility in the treatment of human disease. Here, we show that interleukin (IL) 12 and IL-4 directly induce human neonatal CD4- T cells, activated via CD3 and CD28, to differentiate into Th1 and Th2 subsets. In contrast, IL-13, which shares many biological activities with IL-4, failed to induce T cell differentiation, consistent with the observation that human T cells do not express IL-13 receptors. Both the IL-12-induced Th1 subset and the IL-4-induced Th2 subset produce large quantities of IL-10, confirming that human IL-10 is not a typical human Th2 cytokine. Interestingly, IL-4-driven Th2 cell differentiation was completely prevented by an IL-4 mutant protein (IL-4.Y124D), indicating that this molecule acts as a strong IL-4 receptor antagonist. Analysis of single T cells producing interferon gamma or IL-4 revealed that induction of Th1 cell differentiation occurred rapidly and required only 4 d of priming of the neonatal CD4+ T cells in the presence of IL-12. The IL-12-induced Th1 cell phenotype was stable and was not significantly affected when repeatedly stimulated in the presence of recombinant IL-4. In contrast, the differentiation of Th2 cells occurred slowly and required not only 6 d of priming, but also additional restimulation of the primed CD4+ T cells in the presence of IL-4. Moreover, IL-4-induced Th2 cell phenotypes were not stable and could rapidly be reverted into a population predominantly containing Th0 and Th1 cells, after a single restimulation in the presence of IL-12. The observed differences in stability of IL-12- and IL-4-induced human Th1 and Th2 subsets, respectively, may have implications for cytokine-based therapies of chronic disease.

CD4-Positive T-Lymphocytes↗
PubMed1996

Use of a high affinity DNA ligand in flow cytometry.

To investigate the feasibility of using oligonucleotides in flow cytometry we describe a model system consisting of human neutrophil elastase (HNE) coated on 3.3 micro beads and a high affinity DNA ligand for HNE isolated by in vitro selection (SELEX). In this system the fluoresceinated DNA ligand was equally effective as an anti- HNE antibody in detecting HNE on beads. The location on and the chemistry of attachment of fluorescein to the DNA ligand is critical for the sensitivity of detection. DNA constructs in which fluorescein was conjugated via an ethylene glycol tether to either the 5'-end or near the 3'-end gave much higher signals than did probes with fluorescein directly conjugated to either end. Second-step staining with strepavidin-conjugated phycoerythrin was accomplished using a biotinylated DNA ligand in the initial staining of HNE beads. These data suggest that instead of, or in addition to, antibodies high affinity oligonucleotide probes can be useful in diagnostic applications based on flow cytometry.

Animals↗
PubMed1996

Computed tomography in blunt hepatic trauma.

BACKGROUND: Nonoperative management of blunt hepatic injury in hemodynamically stable trauma patients is now common. Recently, it has been proposed that the finding of hepatic periportal tracking (PPT) of blood on the initial computed tomographic (CT) scan is a sensitive marker of significant hepatic and subhepatic injury that might militate against nonoperative management. While CT scan is useful in diagnosing the injury, the utility of follow-up CT scans has not been elucidated. DESIGN: Retrospective chart review. SETTING: Regional trauma center. PATIENTS: The records of 58 hemodynamically stable patients with blunt hepatic trauma were reviewed and the following data recorded: age, outcome, Injury Severity Score (ISS), operative intervention, and complications. Computed tomographic scans were taken on admission and reviewed for the presence of PPT. The timing and radiographic appearance of follow-up CT scans was also recorded. RESULTS: Seventeen patients (29%) had radiographic evidence of PPT while 41 patients (71%) did not. Age, ISS, injury grade, overall success rate of nonoperative management, and incidence of complications were not statistically significant between the two groups. In no instance did a routine follow-up CT scan affect subsequent management of the patient. CONCLUSIONS: The finding of PPT on the admission CT scan is not clinically significant and does not preclude nonoperative management of patients with blunt hepatic injury. Furthermore, routine follow-up CT scans are not indicated, as treatment is not influenced by their results. Rather, follow-up CT scans should be obtained as dictated by the patient's clinical course. Extrapolation of these findings to all patients with blunt hepatic trauma in the United States would result in considerable savings of health care dollars, without negatively affecting patient care.

Adolescent↗